PubMed Health⌕ Search

Biomedical subjects

N G Anderson

Publications and source records attributed to N G Anderson.

At least 19 recordsLinked to original sources
PubMed1992

Growth hormone activates mitogen-activated protein kinase and S6 kinase and promotes intracellular tyrosine phosphorylation in 3T3-F442A preadipocytes.

Physiological concentrations of growth hormone induced a rapid and transient activation of mitogen-activated protein kinase (MAP kinase) and S6 kinase in 3T3-F442A preadipocytes. These effects were abrogated by staurosporine and in cells chronically pretreated with phorbol esters, suggesting that protein kinase C is involved in the mechanism of activation. In addition, three cytosolic proteins exhibited a growth-hormone-dependent increase in tyrosine phosphorylation.

3T3 Cells↗
PubMed1992

Placental compressibility: implications for indirect diagnosis of posterior placenta previa.

A number of problems beset the indirect diagnosis of posterior placenta previa using transabdominal ultrasound. We add a new potential complicating factor. In 128 pregnancies at or beyond 30 weeks' gestation, measurements were taken from the fetal skull to the maternal sacrum before and after compression. Up to 69% compressibility of the placenta was found in vivo and in vitro. Modified fetal skull to maternal sacrum measurement criteria were devised from the results. Placenta previa is highly unlikely if the measurement from the fetal skull to maternal sacrum is less than 10 mm before compression or less than 7 mm after compression. Placenta previa is probable if the measurement is greater than 20 mm before compression or greater than 15 mm after compression. In 40% of the cases, posterior placenta previa could not be excluded. We conclude that placental compressibility is an additional confounding problem for indirect ultrasound assessment of posterior placenta previa and that indirect assessment should be attempted only if maneuvers to image the lower uterine segment directly are unsuccessful.

Female↗
PubMed1992

Efficacy of fetal part elevation to visualise internal cervical os.

The diagnosis or exclusion of placenta previa is best achieved by direct visualisation of the relationship of the lower edge of the placenta to the internal cervical os. In later pregnancy, the presenting fetal part frequently obscures this area. Elevation of the presenting part was attempted in 56 consecutive pregnancies of greater than 30 weeks gestation, with a success rate of 71%. This confirms that in a minority of pregnancies, other manoeuvres or ultrasound techniques are necessary to visualise the lower placental margin directly.

Female↗
PubMed1992

Prognosis in fetal cystic hygroma.

Axillary and lateral cervical fetal cystic hygromas in a fetus with normal karyotype are described. Fetal death at 25 weeks' gestation occurred. A literature review revealed that for cystic hygroma 42% of infants are 45XO, 38% have a normal karyotype, and 18% have trisomies. Prognosis is grim if the karyotype is abnormal or if hydrops or bilateral pleural effusions are present. Survival rate progressively improves with normal karyotype (27%), unilateral pleural effusion (40%), atypical location (56%), and resolution of cystic hygroma (71%). No single feature signifies 100% survival. The overall survival rate for fetal cystic hygroma is 10%. Prognosis remains guarded regardless of all other factors until the fetus reaches 26 weeks' gestation, after which time a 67% chance of ultimate survival can be expected. Only 42% of documented survivors were completely normal at follow-up.

Axilla↗
PubMed1991

Raf-1 is a potential substrate for mitogen-activated protein kinase in vivo.

MAP (mitogen-activated protein) kinase is shown to phosphorylate baculovirally expressed Raf-1 in vitro, generating one major tryptic phosphopeptide which co-migrated with a peptide from Raf-1 32P-labelled in situ. This peptide also undergoes an insulin-dependent increase in labelling. Thus the serine/threonine kinase Raf-1 may be a substrate for MAP kinase in vivo.

Animals↗
PubMed1991

Activation of mitogen-activated protein kinase in BC3H1 myocytes by fluoroaluminate.

Treatment of BC3H1 myocytes or 3T3-L1 fibroblasts with fluoroaluminate (AlF4-), a direct activator of G proteins, increased the tyrosine phosphorylation of a 42-kDa cytosolic protein. AlF4- induced a parallel increase in protein kinase activity toward myelin basic protein (MBP) in partially purified cell extracts. To test whether AlF4- was activating the 42-kDa MAP (mitogen-activated protein) kinase, extracts from AlF4--treated cells were taken through the chromatographic steps routinely used to purify MAP kinase from growth factor-stimulated cells. Following phenyl-Superose chromatography, a peak of MBP kinase activity eluted at a position characteristic of MAP kinase. Immunoblotting of the active fractions with anti-phosphotyrosine antibodies revealed a single reactive protein band of Mr 42,000. Stimulation of MAP kinase by AlF4- was rapid, peaking within 15 min and persisting for at least 1 h. In contrast, the activation of MAP kinase by insulin was transient, characteristic of its activation by growth factors in other cell types. Although concentrations of sodium fluoride greater than 1 mM also activated MAP kinase, this effect was shown to be dependent upon the simultaneous presence of aluminum ions in the medium. Activation of MAP kinase by AlF4- was not affected by either cellular depletion of protein kinase C or pretreatment of cells with pertussis toxin. Potential sites of action of AlF4- are discussed. These findings suggest that activation of a G protein(s) in intact cells can initiate events that result in tyrosine phosphorylation and activation of MAP kinase.

Aluminum↗
PubMed1991

A two-dimensional gel database of human plasma proteins.

An updated two-dimensional electrophoretic map of human plasma proteins is presented, together with a complete listing of the individual protein spots, their locations, size and isoelectric points relative to internal charge standards. Forty-nine polypeptide species are identified, many consisting of multiple spots differing in glycosylation or sequence (e.g., immunoglobulins). A further series of 35 as yet uncharacterized proteins is indicated.

Blood Proteins↗
PubMed1991

A two-dimensional gel database of rat liver proteins useful in gene regulation and drug effects studies.

A standard two-dimensional (2-D) protein map of Fischer 344 rat liver (F344MST3) is presented, with a tabular listing of more than 1200 protein species. Sodium dodecyl sulfate (SDS) molecular mass and isoelectric point have been established, based on positions of numerous internal standards. This map has been used to connect and compare hundreds of 2-D gels of rat liver samples from a variety of studies, and forms the nucleus of an expanding database describing rat liver proteins and their regulation by various drugs and toxic agents. An example of such a study, involving regulation of cholesterol synthesis by cholesterol-lowering drugs and a high-cholesterol diet, is presented. Since the map has been obtained with a widely used and highly reproducible 2-D gel system (the Iso-Dalt system), it can be directly related to an expanding body of work in other laboratories.

Animals↗
PubMed1991

Normal size left ventricle on antenatal scan in lethal hypoplastic left heart syndrome.

We present a case of lethal hypoplastic left heart syndrome missed at routine 20-week antenatal ultrasound examination because the left ventricle was of normal size on the standard four-chamber cardiac view. Hypoplastic left heart syndrome includes a spectrum of cardiac malformations. This case illustrates the difficulty in excluding the diagnosis of hypoplastic left heart syndrome on a single view from one antenatal second-trimester ultrasound examination.

Diagnostic Errors↗
PubMed1990

Requirement for integration of signals from two distinct phosphorylation pathways for activation of MAP kinase.

MAP kinase (relative molecular mass, 42,000), a low abundance serine--threonine protein kinase, is transiently activated in many cell types by a variety of mitogens, including insulin, epidermal growth factor, and phorbol esters. In vitro, MAP kinase will phosphorylate and reactivate S6 kinase II previously inactivated by phosphatase treatment. Because many of the stimuli that activate MAP kinase are also stimulators of cell proliferation, and regulation of the cell cycle seems to involve a network of protein kinases, MAP kinase could be important in the transmission of stimuli eventually leading to the progression from G0 to G1 in the cell cycle. Activated MAP kinase contains both phosphotyrosine and phosphothreonine. We report here that MAP kinase can be deactivated completely by treatment with either phosphatase 2A, a protein phosphatase specific for phosphoserine and phosphothreonine, or CD45, a phosphotyrosine-specific protein phosphatase. We demonstrate that MAP kinase is only active when both tyrosyl and threonyl residues are phosphorylated and suggest therefore that the enzyme functions in vivo to integrate signals from two distinct transduction pathways.

Adenosine Triphosphate↗