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Biomedical subjects

M L Zimmerman

Publications and source records attributed to M L Zimmerman.

11 recordsLinked to original sources
PubMed1998

Lipid structure and not membrane structure is the major determinant in the regulation of protein kinase C by phosphatidylserine.

This study addresses the molecular basis for protein kinase C's specific activation by phosphatidylserine. Specifically, we ask whether protein kinase C's phospholipid specificity arises from specific protein/lipid interactions or whether it arises from unique membrane-structuring properties of phosphatidylserine. We measured the interaction of protein kinase C betaII to membranes that differed only in being enantiomers to one another: physical properties such as acyl chain composition, membrane fluidity, surface curvature, microdomains, headgroup packing, and H-bonding with water were identical. Binding and activity measurements reveal that protein kinase C specifically recognizes 1, 2-sn-phosphatidyl-L-serine, independently of membrane structure. High-affinity binding and activation are abolished in the presence of enantiomeric membranes containing 2,3-sn-phosphatidyl-L-serine, 2, 3-sn-diacylglycerol, and 2,3-sn-phosphatidylcholine. Our data also show that the stereoselectivity for 1,2-sn-diacylglycerol is not absolute; 2,3-sn-diacylglycerol modestly increases the membrane affinity of protein kinase C provided that 1, 2-sn-phosphatidyl-L-serine is present. We also find that the stereochemistry of the bulk phospholipid, in this case phosphatidylcholine, has no significant influence on protein kinase C's membrane interaction. These data reveal that specific molecular determinants on protein kinase C stereospecifically recognize structural determinants of phosphatidylserine.

Binding Sites↗
PubMed1993

Regulation of a candidate aminophospholipid-transporting ATPase by lipid.

The effect of lipid environment on the activation of a vanadate-sensitive Mg(2+)-ATPase purified from human erythrocytes was studied in detergent-lipid-protein mixed micelles. ATPase activity was stimulated maximally by phosphatidylserine. Other anionic diacylglycerophospholipids (phosphatidic acid, cardiolipin, phosphatidylglycerol, and phosphatidylinositol) supported 25-100% of the phosphatidylserine-stimulated activity. Another aminophospholipid, egg PE, supported 38% of the phosphatidylserine-stimulated activity. The phosphoinositides (phosphatidylinositol, phosphatidylinositol 4-phosphate, phosphatidylinositol 4,5-bisphosphate) also stimulated the ATPase; however, activity decreased with increasing lipid phosphorylation. Monoacyl negatively charged lipids (lysophosphatidylserine, fatty acids) and zwitterionic lipids (phosphatidylcholine and sphingomyelin) did not activate the enzyme. ATPase activation was dependent on phospholipid fatty acyl chain composition: ATPase activity increased with increasing PS acyl chain length, and the optimal fatty acid composition was one saturated and one unsaturated fatty acid. However, the long, unsaturated acyl chain requirement could be satisfied by nonactivating lipids. The characteristics of this ATPase are similar to those of the Mg(2+)-ATP-dependent aminophospholipid flippase, suggesting that it may be associated with the transporter.

Animals↗
PubMed1990

The sexual addict: a challenge for the primary care provider.

Sexual compulsion is now recognized as a true addictive process that may manifest itself through a wide range of behaviors. Recognition of this disorder in primary care settings may be difficult because of the ego defenses of denial and rationalization that characterize this disorder. Cues in the medical and sexual history as well as behavioral cues may suggest the presence of sexual addiction. The alert primary care provider should play a significant role in the recognition of sexual addiction.

Adaptation, Psychological↗
PubMed1987

The effect of smokeless-tobacco extracts on the growth of oral bacteria of the genus Streptococcus.

Aqueous tobacco extracts were used to supplement a basic salts solution (BSS) and a microbial medium. Thin-layer chromatography revealed sucrose in only one of four extracts. Discs saturated with extracts (0.1-50 mg/ml) failed to inhibit growth of any of the micro-organisms. Supplementation (10 mg/ml) of BSS with the tobaccos lacking sucrose resulted in augmented growth of Streptococcus mutans, Streptococcus salivarius and Streptococcus sanguis whereas the sucrose-containing brand augmented only Strep. sanguis growth. Thus extracts of these smokeless tobaccos would serve as a growth substrate for three species of oral streptococci which are frequently associated with human dental caries.

Bacteriological Techniques↗
PubMed1985

Differences between intra- and extracellular interleukin-1.

The intracellular (IC) and extracellular (EC) pools of interleukin 1 (IL-1) of human monocyte cultures were found to differ in their molecular size and charge characteristics. EC activity was found by Sephadex G-75 chromatography to consist mainly of a single peak in the 15,000-17,000 mol. wt range. In contrast, IC activity was distributed in four peaks (mol. wts of approx. 15,000, 26,000, 45,000 and greater than 70,000). Treatment of a pool of the IC 26,000, 45,000 and greater than 70,000 mol. wt species with CHAPS, a zwitterionic detergent, yielded a large amount of the 15,000 mol. wt species, thus suggesting that a portion of the larger species consists of aggregates of the 15,000 mol. wt molecule. Both IL-1 pools were found by isoelectrofocusing to be composed of three molecular species with pIs of 5.5, 6.7. However, the proportions of these species differed markedly between the EC and IC pools. The large majority of IC activity (approximately 90%) was found at pI 5.5, while 55-60% of EC activity had a pI of 6.7 and 35-40% had a pI of 5.5. The differences in their biophysical properties support the notion that the IC and EC pools of IL-1 also differ in their functions.

Cells, Cultured↗
PubMed1980

Demonstration of an R plasmid in a strain of Pasteurella haemolytica isolated from feedlot cattle.

A strain of Pasteurella haemolytica isolated from the lungs of feedlot cattle with pneumonia was shown to be resistant to ampicillin, tetracycline, and streptomycin. Two small, nontransmissible plasmids were shown to be responsible, for tetracycline resistance, a 5.7 X 10(6) dalton plasmid, and for streptomycin resistance, a 5.5 X 10(6) dalton plasmid. Ampicillin resistance passed by transformation to Escherichia coli could not be shown conclusively to be on a plasmid. Ampicillin resistance was shown to be mediated by means of a beta-lactamase with high activity against cephaloridine.

Ampicillin↗
PubMedDate not supplied

Identification of Ahasverus advena (Waltl) (foreign grain beetle) and Ahasverus rectus (LeConte) (Coleoptera: Cucujidae) by micromorphology of adult fragments including genitalia.

Morphological characteristics of dissected fragments from male and female adult beetles of Ahasverus advena (Waltl) and A. rectus (LeConte) are described and illustrated, including original descriptions of the male genitalia of both species. Diagnostic differences are noted among the morphology of the head, antennae, mandibles, labium, tibial leg segments, prothorax, metasternum, and abdominal sternite I, and between the shape and/or setation of the paired lateral lobes, the apical margin of the aedeagus, the internal sac, and the paired 8th and 9th abdominal sternites for the male genitalia.

Animals↗
PubMedDate not supplied

Sex roles in instructional materials: testing the stereotypes.

This special report discusses the significance and potential benefit of portraying men in nontraditional sex roles within pictorial instructional print materials on health and child care. It is based on the cognitive and behavioral findings of a comparative research study conducted in selected rural and periurban areas of Mexico on the use of two versions of an ORS pictorial pamphlet. Major findings of the study were: (1) portraying nontraditional sex roles for men in the ORS pamphlet did not reduce the credibility of technical information contained in the pamphlet; (2) a significantly greater number of subjects preferred the version that portrayed the father figure as co-caretaker of a sick child. These unexpected results have important implications for instructional and motivational communication and health education projects throughout the developing world.

Father-Child Relations↗