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Biomedical subjects

R Anderson

Publications and source records attributed to R Anderson.

At least 361 records · Page 20Linked to original sources
PubMed1993

Maintenance of ZPA signaling in cultured mouse limb bud cells.

The positional signal localized to the posterior (zone of polarizing activity or ZPA) region of the vertebrate limb is transiently expressed during development and a decline in ZPA signaling is accelerated when posterior cells are dissociated and cultured in vitro. The evidence that cultured posterior cells display a precocious decline in ZPA signaling when compared to in vivo studies suggests that a factor present in the limb bud maintains or stabilizes ZPA signaling during limb outgrowth and that this maintenance factor is lost and/or exhausted in in vitro studies. We have developed a new culture technique, 'microdissociation', which preserves extracellular components that we have found to be necessary for ZPA signal maintenance. Our data suggest that the limb bud ectoderm produces a maintenance activity that becomes stored in the extracellular matrix where it acts on limb bud cells to stabilize the activity of the ZPA signal. Using our initial characterization of this maintenance activity, we have identified a growth factor, FGF-2 (bFGF), that can replace all of the ZPA signaling maintenance activity observed in microdissociate cultures. The existence of various members of the FGF family in the developing limb strongly argues a role for FGF in stabilizing ZPA signaling in vivo.

Animals↗
PubMed1993

Alpha-fetoprotein in diabetic pregnancy. A reassessment.

We correlated glycosylated hemoglobin (HbA1) with maternal serum alpha-fetoprotein (MSAFP) in 92 and amniotic fluid AFP (AFAFP) in 27 patients with pregestational and gestational diabetes. MSAFP and AFAFP were measured between 15 and 20 weeks and correlated with HbA1. In group 1, HbA1 was measured at < or = 12 weeks' gestation; in group 2, it was measured 0-6 weeks before MSAFP measurement; and in group 3, it was measured within 6 weeks after MSAFP. Mean MSAFP was 1.02 +/- 0.77 multiples of the median (MOM) (+/- SD) in all diabetics, 1.1 +/- 0.93 MOM in gestational diabetics and 0.89 +/- 0.33 MOM in pregestational diabetics (P = NS). There was no correlation between MSAFP and HbA1 in groups 1-3. Patients with HbA1 > 9 g% had a mean MSAFP of 0.84 MOM as compared to 0.85 MOM in those with HbA1 < 9 g% (P = NS). AFAFP values were within normal limits even in patients with HbA1 > 9 g% in early pregnancy (n = 8). No significant decrease in MSAFP was seen in pregestational diabetics, and no correlation was seen with HbA1 levels. AFAFP levels were unchanged in diabetics.

Amniotic Fluid↗
PubMed1993

Stability of intact chorionic gonadotropin (hCG) in serum, liquid whole blood, and dried whole-blood filter-paper spots: impact on screening for Down syndrome by measurement of free beta-hCG subunit.

The use of multiple maternal serum biochemical markers in screening for Down syndrome is gaining worldwide acceptance. We sought to study the impact of the potential instability of intact human chorionic gonadotropin (hCG) on free beta-hCG subunit, a marker that has recently been used successfully in such screening. We found that, in practice, any changes in free beta-hCG due to the instability of intact hCG do not inhibit the effectiveness of free beta-hCG as a marker for Down syndrome. This was proven by controlled laboratory experiments at various stress temperatures, freeze-thaw studies, and analysis of a large set of screening data with particular reference to time in transit for individual samples. Data from controlled dissociation studies demonstrate that any apparent increase in free beta-hCG due to the instability of intact hCG cannot be attributed simply to the dissociation of intact hCG. Finally, for large-scale mass population screening in areas of the world where transport delays, safety concerns, and high temperatures preclude the shipment of liquid whole blood, dried whole-blood spots in filter paper provide a suitable delivery system with many advantages.

Blood Specimen Collection↗
PubMed1993

Lysophospholipid-mediated inhibition of Na+,K(+)-adenosine triphosphatase is a possible mechanism of immunosuppressive activity of cyclosporin A.

The relationship between the phospholipase-stimulating and immunosuppressive properties of cyclosporin A (CsA) has been investigated in vitro. At concentrations of 0.025 microM and upwards, CsA caused dose-related inhibition of both mitogen- and alloantigen-stimulated uptake of tritiated thymidine by human mononuclear leukocytes (MNL), which was associated with a time- and dose-related enhancement of the generation of lysophosphatidylcholine (LPC), arachidonic acid, and prostaglandin E2 from mitogen-stimulated cells. Arachidonate alone, at concentrations of up to 20 microM, did not affect lymphocyte activation, whereas cyclooxygenase and 5'-lipoxygenase inhibitors failed to protect the cells against the antiproliferative effects of CsA. However, LPC caused dose-related inhibition of MNL proliferation. Moreover, coincubation of MNL with alpha-tocopherol, a lysophospholipid-complexing agent, or with lysophospholipase protected the cells against CsA, as well as against LPC. The Na+,K(+)-ATPase activity of mitogen-activated lymphocytes was also inhibited by CsA, whereas inclusion of alpha-tocopherol or lysophospholipase protected this enzyme. Excessive production of lysophospholipids and consequent inhibition of Na+,K(+)-ATPase during CsA treatment of mitogen- or antigen-activated lymphocytes is a possible biochemical mechanism of the immunosuppressive activity of this agent.

Adult↗
PubMed1993

Signs and symptoms of "asymptomatic" HIV-1 infection in homosexual men. Multicenter AIDS Cohort Study.

We investigated the long-term health effects of HIV-1 infection in homosexual men not close to developing AIDS by comparing 916 HIV-1-seropositive (SP) men at least 1.67-3.67 years prior to a clinical AIDS diagnosis to 2,161 HIV-1-seronegative (SN) controls. The SP group reported a higher total of 12 distinct symptoms (fatigue, shortness of breath, night sweats, rash, cough, diarrhea, headache, thrush, skin discoloration, fever, weight loss, and sore throat/mouth) than did the SN group (p < 0.0001), corresponding to at least 5.6 more days/year of such symptoms. The SP group had lower body mass index (p < 0.0001) and lower hemoglobin (p < 0.0001). The SP group was more depressed, as measured by CES-D score (p = 0.047), before knowledge of one's serostatus was likely, and became even further depressed (p = 0.038 for increase in depression) after the HIV-1 serostatus test was accessible to high-risk groups. These associations remained unchanged in multivariate models, incorporating other covariates.

Analysis of Variance↗
PubMed1993

Achieving healthy weights.

Only 5% of patients dieting to achieve permanent weight loss will be successful and reap the associated health benefits. Ninety-five percent will be unsuccessful. The health implications of failed dieting attempts are numerous and include negative effects on both physical and psychological well-being. Better alternatives to dieting help patients take small, positive, enjoyable steps toward healthy eating, active living, and a positive self-image.

Body Composition↗
PubMed1993

Surveillance of serious recreational injuries: a capture-recapture approach.

Serious injury from sport and recreation is a leading cause of morbidity and mortality in the United States. Historically, occurrences of diseases with substantial public health impact have been monitored via surveillance systems in order to obtain information concerning the frequency with which the diseases occur. Surveillance leads to efforts that identify risk factors, and eventually, control measures to reduce the incidence of disease. Currently, the surveillance of sports injury represents only limited coverage in the U.S. It is important to begin discussions regarding approaches toward the development of surveillance of these injuries. Methods based upon the communicable disease surveillance model could potentially be used to monitor serious sports injuries. One method of surveillance, using the statistical approach of capture-mark-recapture, is presented as an example by which a national system of surveillance of serious sports injury could be established.

Athletic Injuries↗
PubMed1992

Fasting in the rat does not induce hyperfibrinogenaemia.

The effects of fasting in the rat on the plasma fibrinogen concentration have been investigated. Fasting for 24-48 hr produced the expected sustained increase (4-5-fold) in the concentrations in the plasma of non-esterified fatty acids, but no accompanying increase in that of fibrinogen was detected.

Animals↗
PubMed1992

A peroxidase-independent method for the quantitation of extracellular hydrogen peroxide generated by activated phagocytes in vitro.

A peroxidase-independent method for the determination of phagocyte-derived hydrogen peroxide in vitro is described. The method is based on the catalase-inhibitable oxidation of added cysteine. Human blood neutrophils (1 x 10(6)/ml) were coincubated with the myeloperoxidase (MPO) inhibitor, sodium azide (10 micrograms/ml), for 30 min at 37 degrees C followed by addition of phorbol 12-myristate 13-acetate (PMA, 10 ng/ml), a potent activator of membrane-associated oxidative metabolism. After incubation at 37 degrees C the cells were removed and the supernatants aliquoted and incubated with and without catalase (500 U/ml) for 10 min at room temperature followed by addition of cysteine (50 microM). Thereafter the catalase-inhibitable, H2O2-mediated oxidation of added cysteine was assayed spectrophotometrically following the addition of the thiol-reactive agent 5,5'-dithiobis-(2-nitrobenzoic acid), and the H2O2 concentration determined using a standard curve constructed from difference data based on the oxidation of cysteine by H2O2 (0-200 nmol). The average amount of H2O2 produced by 10(6) PMA-activated neutrophils was 47 +/- 7 nmol/30 min. This sensitive assay procedure is likely to be particularly useful for investigating the effects of pharmacological agents and anti-oxidant nutrients on H2O2 production by activated phagocytes, since these agents are generally unsuited for use in peroxidase-based assays.

Azides↗
PubMed1992

Black-white mortality differences by family income.

Death rates among US black men and women under 75 years of age are higher than for their white counterparts. The explanation for this excess risk, though attributed to socioeconomic factors, remains unclear. We calculated mortality rates by family income for blacks and whites in a representative sample of the US population (National Longitudinal Mortality Study). For persons aged less than 65 years of age, mortality rates are lower in those with higher family income for both blacks and whites, and both men and women. However, at each level of income, blacks have higher mortality than whites. Higher levels of family income are also associated with lower death rates from cardiovascular disease, cancer, and deaths from causes other than cardiovascular disease or cancer. After adjustment for income, blacks have higher death rates from each of these three general causes. For subjects below 65 years, the mortality gradient by income is larger than the gradient by race. The differences in mortality rates by race not accounted for by income may be due to other differences such as access to health care, type or quality of medical care, or behavioral risk factors that disadvantage black populations.

Adult↗
PubMed1992

Ty1-copia group retrotransposons are ubiquitous and heterogeneous in higher plants.

We have used the polymerase chain reaction to isolate fragments of Ty1-copia group retrotransposons from a wide variety of members of the higher plant kingdom. 56 out of 57 species tested generate an amplified fragment of the size expected for reverse transcriptase fragments of Ty1-copia group retrotransposons. Sequence analysis of subclones shows that the PCR fragments display varying degrees of sequence heterogeneity. Sequence heterogeneity therefore seems a general property of Ty1-copia group retrotransposons of higher plants, in contrast to the limited diversity seen in retrotransposons of Saccharomyces cerevisiae and Drosophila melanogaster. Phylogenetic analysis of all these sequences shows, with some significant exceptions, that the degree of sequence divergence in the retrotransposon populations between any pair of species is proportional to the evolutionary distance between those species. This implies that sequence divergence during vertical transmission of Ty1-copia group retrotransposons within plant lineages has been a major factor in the evolution of Ty1-copia group retrotransposons in higher plants. Additionally, we suggest that horizontal transmission of this transposon group between different species has also played a role in this process.

Amino Acid Sequence↗