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Biomedical subjects

R L Jackson

Publications and source records attributed to R L Jackson.

At least 235 records · Page 13Linked to original sources
PubMed1975

The primary structure of human plasma high density apolipoprotein glutamine I (ApoA-I). II. The amino acid sequence and alignment of cyanogen bromide fragments IV, III, and I.

Apolipoprotein glutamine I (apoLP-Gln-I or apoA-I) is the major protein constituent of the human plasma high density lipoproteins. Cleavage of this protein with cyanogen bromide yields four fragments, designated in the order of elution from Bio-Gel P-30 as CNBr I, II, III, and IV. In the first paper in this series, the amino acid sequence of the NH2-terminal fragment, CNBr II, is reported. In the present study, CNBr IV, III, and I, containing, respectively, 25, 36, and 94 amino acids were sequenced by conventional means. To establish the alignment of the cyanogen bromide fragments, apoLP-Gln-I was digested with trypsin and two of the three methionine-containing tryptic peptides were isolated. The amino acid sequence of apoLP-Gln-I is as follows: (see article). With the complete amino acid sequence available, a CPK space-filling model of apoLP-Gln-I was constructed. The protein was placed into an alpha helical conformation wherever the primary structure permitted. Thirteen helical regions were identified. These regions account for 70% of the amino acid residues of the protein. Each helix is characterized as having two faces (amphipathic). One is a polar face that occupies approximately 180 degrees of the surface of the helix and the other is a hydrophobic face that occupies the other 180 degrees of the helical surface. Similar amphipathic helices have been identified previously in the other lipoprotein-proteins that have known sequences. It is suggested that the amphipathic helical regions of apoLP-Gln-I are important in the binding of phospholipids in high density lipoproteins.

Amino Acid Sequence↗
PubMed1975

The mechanism of lipid-binding by plasma lipoproteins.

In this article, we review the current state of knowledge about the structure of human plasma high density lipoproteins. Recent advances in this field, including amino acid sequencing and lipid-binding studies, suggest that the plasma lipoproteins have specific sites with special structural features that account for their ability to bind and transport lipid. A hypothesis which describes the structure of these lipid-binding sites and their interaction with lipid is presented.

Amino Acids↗
PubMed1975

Localization patterns of plasma apolipoproteins in human atherosclerotic lesions.

The localization patterns of human plasma lipoproteins and their respective apoproteins and of neutral lipid were determined in normal and atherosclerotic arteries. Specific antisera were prepared against plasma low-density lipoproteins(LDL) and their apoproteins (apoB), high-density lipoproteins(HDL) and one of their major apoproteins (apoA-I1, and apoC-III, which is a major apoprotein of very low-density lipoproteins (VLDL). Using immunofluorescence techniques, the various antigens were localized in arterial samples obtained at surgery or autopsy. The three apoproteins and neutral lipid were localized to the same tissue areas, namely, lipid core regions and certain connective tissue of atherosclerotic lesions, in 61% of the fibrous plaques and 48% of the fatty streaks examined. In marked contrast, none of the uninvolved arterial regions showed the presence of all four factors together. As controls, the localization of other serum proteins was also determined in these arteries using immunofluorescence techniques. Fibrinogen was associated with regions of maximum complementary localization of factors in 37% of the fibrous plaques and 64% of the fatty streaks. However, albumin was found in only 4-5% of these same regions. The present results suggest that not only LDL but also HDL and VLDL or their respective apoproteins as well as fibrinogen are specifically retained by certain tissue components of the atherosclerotic lesion.

Adolescent↗
PubMed1975

Lipoproteins in atherosclerotic lesions. Localization by immunofluorescence of apo-low density lipoproteins in human atherosclerotic arteries from normal and hyperlipoproteinemics.

Using immunofluorescence techniques, apoLDL, the major protein component of human plasma low and very low density lipoproteins was localized in athersclerotic lesions from the aorta, coronary, and carotid arteries in human normolipoproteinemic, type II, and type IV hyperlipoproteinemics. Although no apoLDL was detected in uninvolved arteries, atheromas from advanced lesions as well as certain collagen and elastic fibers from both fatty streaks and advanced lesions were positive for apoLDL. This localization pattern was the same in each lipemic group, except for the presence of apoLDL in some intimal cells from type II cases. However, extensiveness of apoLDL localization was greatest in the type II group, but equal in the normolipemic and type II group. This may be explained by the high concentration gradient between plasma and tissue for apoLDL in the type II group.

Adult↗
PubMed1975

A biological environmental chamber for the culture of Neisseria gonorrhoeae.

The control of gonorrhea is enhanced by the rapid and accurate detection of the causative organism through use of bacteriological culture techniques. The culture medium of Thayer and Martin is the medium of choice for cultivating Neisseria gonorrhoeae from specimens suspected of harboring this organism. The validity of culture results often depends on how the inoculated medium was handled before it arrived in the laboratory. Several procedures have been suggested for providing adequate environmental conditions for the survival and growth of the gonococcus. After examining various methods, we conclude that the method employing the Biological Environmental Chamber is an improvement over other methods. The chamber is a convenient and workable container for microbiological cultures.

Bacteriological Techniques↗
PubMed1974

The primary structure of high density apolipoprotein-glutamine-I.

The major protein constituent of human plasma high density lipoproteins has been isolated and its complete amino-acid sequence determined. The protein, designated apolipoprotein-glutamine-I by the presence of carboxyl-terminal glutamine, is a single polypeptide chain of 245 amino-acid residues, including three residues of methionine. The protein is devoid of cysteine, cystine, and isoleucine. Cleavage of apolipoprotein-glutamine-I with cyanogen bromide yields four fragments with 94, 90, 36, and 25 amino acids. The amino-acid sequence of each fragment was determined by conventional methods, with proteolytic digestion with trypsin, chymotrypsin, and thermolysin. The alignment of the cyanogen bromide fragments was determined by the isolation of the methionine-containing tryptic peptides from apolipoprotein-glutamine-I. Inspection of the sequence of apolipoprotein-glutamine-I suggests an interesting distribution of amino acids that may account for its helical structure and its ability to bind and transport lipid.

Amino Acid Sequence↗
PubMed1974

Programming the generalization of a greeting response in four retarded children.

Reinforcement techniques of prompting and shaping were employed to develop handwaving, a useful social greeting response, in four institutionalized retarded subjects. A multiple-baseline design across subjects demonstrated the reliable functioning of the training procedures. Specifically, it showed that training and maintenance of the greeting response by one experimenter was not usually sufficient for generalization of the response to the more than 20 other members of the institution staff who had not participated in the training of the response. However, high levels of generalization to staff members were recorded for three subjects over periods ranging from one to six months after a second experimenter trained and maintained the response in conjunction with the first experimenter. The fourth subject, although never receiving training by a second experimenter, showed similar results following a second training by the first experimenter.

Adolescent↗