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Biomedical subjects

S M White

Publications and source records attributed to S M White.

At least 55 records · Page 3Linked to original sources
PubMed2001

Erythema elevatum diutinum in a patient with human immunodeficiency virus.

Erythema elevatum diutinum (EED) is a chronic cutaneous leukocytoclastic vasculitis. This rare disease is characterized by red, brownish-purple, and yellow papules, plaques, and nodules distributed symmetrically about the extremities. There have been recent reports of the disease in association with infection with the human immunodeficiency virus (HIV). We describe the case of a 51-year-old man with HIV who presented with EED, which was successfully treated with dapsone.

Anti-Infective Agents↗
PubMed2000

Inhibition of granulocyte colony-stimulating factor-mediated myeloid maturation by low level expression of the differentiation-defective class IV granulocyte colony-stimulating factor receptor isoform.

In acute myeloid leukemia (AML), granulocyte colony-stimulating factor receptor (G-CSFR) proliferative and maturational signaling pathways are uncoupled. Seven human G-CSFR mRNA isoforms exist, named class I through class VII. The 183-amino acid cytosolic domain of the class I isoform provides all signaling activities. The class IV isoform is "differentiation defective" because the carboxy-terminal 87 amino acids are replaced with 34 amino acids of novel sequence. In more than 50% of AML samples, the class IV/class I G-CSFR mRNA ratio is aberrantly elevated compared to normal CD34(+) bone marrow cells. We hypothesized that the increased relative expression of class IV G-CSFR in AML uncouples proliferative and maturational G-CSFR signaling pathways. To test this, we transfected the G-CSF-responsive murine cell line 32Dcl3 with class IV G-CSFR cDNA. After 10 days of G-CSF stimulation, clones expressing class IV G-CSFR had greater percentages of myeloblasts and promyelocytes than controls (53% +/- 13% versus 3% +/- 2%). Differential counts over time demonstrated delayed G-CSF-driven maturation in 5 class IV-expressing clones, with 2 clones demonstrating a subpopulation that completely failed to differentiate. Heterologous class IV expression did not affect G-CSF-dependent proliferation. Class IV/murine G-CSFR mRNA ratios after 24 hours of G-CSF stimulation for 3 of the 5 clones (range, 0. 090 to 0.245; mean, 0.152 +/- 0.055) are within the range of class IV/class I mRNA ratios seen in patients with AML. This indicates that aberrantly increased relative class IV G-CSFR expression seen in AML can uncouple G-CSFR proliferative and maturational signaling pathways.

Animals↗
PubMed2000

Megacystis-microcolon-intestinal hypoperistalsis syndrome: the difficulties with antenatal diagnosis. Case report and review of the literature.

Megacystis on antenatal scan in female fetuses is rare and has serious diagnostic implications. We report two cases of megacystis-microcolon-intestinal hypoperistalsis syndrome (MMIHS) in female infants in whom antenatal scan abnormalities were identified, but the diagnosis not made until after delivery. MMIHS is a rare autosomal recessive condition which is usually lethal in the first year of life. Prenatal diagnosis is hampered by the lack of specific diagnostic findings on ultrasound and the absence of an identified genetic locus. The prenatal findings in MMIHS are reviewed and contrasted with those of other causes of lower abdominal masses on antenatal ultrasound.

Abnormalities, Multiple↗
PubMed1999

Lentivirus vectors using human and simian immunodeficiency virus elements.

Lentivirus vectors based on human immunodeficiency virus (HIV) type 1 (HIV-1) constitute a recent development in the field of gene therapy. A key property of HIV-1-derived vectors is their ability to infect nondividing cells. Although high-titer HIV-1-derived vectors have been produced, concerns regarding safety still exist. Safety concerns arise mainly from the possibility of recombination between transfer and packaging vectors, which may give rise to replication-competent viruses with pathogenic potential. We describe a novel lentivirus vector which is based on HIV, simian immunodeficiency virus (SIV), and vesicular stomatitis virus (VSV) and which we refer to as HIV/SIVpack/G. In this system, an HIV-1-derived genome is encapsidated by SIVmac core particles. These core particles are pseudotyped with VSV glycoprotein G. Because the nucleotide homology between HIV-1 and SIVmac is low, the likelihood of recombination between vector elements should be reduced. In addition, the packaging construct (SIVpack) for this lentivirus system was derived from SIVmac1A11, a nonvirulent SIV strain. Thus, the potential for pathogenicity with this vector system is minimal. The transduction ability of HIV/SIVpack/G was demonstrated with immortalized human lymphocytes, human primary macrophages, human bone marrow-derived CD34(+) cells, and primary mouse neurons. To our knowledge, these experiments constitute the first demonstration that the HIV-1-derived genome can be packaged by an SIVmac capsid. We demonstrate that the lentivirus vector described here recapitulates the biological properties of HIV-1-derived vectors, although with increased potential for safety in humans.

Animals↗
PubMed1999

Purinoceptor-mediated calcium signaling in preglomerular smooth muscle cells.

-The current studies were performed to determine the contribution of calcium mobilization and voltage-dependent calcium influx to the increase in [Ca2+]i elicited by ATP and UTP. Suspensions of freshly isolated smooth muscle cells were prepared from preglomerular microvessels by enzymatic digestion and loaded with the Ca2+-sensitive dye fura 2. The effect of ATP and UTP on [Ca2+]i was studied on single cells with standard microscope-based fluorescence photometry techniques. Resting [Ca2+]i averaged 80+/-3 nmol/L (n=219 single cells from 58 dispersions). ATP (100 micromol/L) increased [Ca2+]i to a peak value of 845+/-55 nmol/L (n=70 single cells from 38 dispersions) before stabilizing at 124+/-81 nmol/L. Similarly, 100 micromol/L UTP (n=39 single cells from 26 dispersions) stimulated a peak increase in [Ca2+]i of 1426+/-584 nmol/L before reaching a stable plateau of 123+/-10 nmol/L. The [Ca2+]i response to ATP and UTP was also assessed in the absence of extracellular calcium. In these studies, exposure to 100 micromol/L ATP induced a transient peak increase in [Ca2+]i, with the plateau phase being totally abolished. In contrast, exposure to 100 micromol/L UTP under calcium-free conditions resulted in no detectable change in the UTP-mediated increase in [Ca2+]i. The role of L-type calcium channels in the response was assessed with the calcium channel antagonist diltiazem. Incubation with diltiazem (10 micromol/L) markedly reduced the response to ATP, whereas the response to UTP was only slightly reduced. These data demonstrate that both ATP and UTP directly stimulate a biphasic increase in [Ca2+]i in renal microvascular smooth muscle cells. Furthermore, the data suggest that the elevation of [Ca2+]i elicited by ATP is largely dependent on calcium influx through L-type calcium channels, whereas the response to UTP appears to derive primarily from mobilization of calcium from intracellular stores.

Adenosine Triphosphate↗
PubMed1999

Heteronegativism? The attitudes of gay men and lesbians toward heterosexuals.

Although many studies have been conducted on homophobia, little information exists about the attitudes of homosexuals toward heterosexuals. In order to compare the attitudes of both groups, a well-known homophobia questionnaire (Hudson & Ricketts, 1980) was reworded to assess the attitudes of homosexuals toward heterosexuals, forming a "heterophobia" questionnaire. The less clinical term "heteronegativism" is introduced here to refer to the range of negative feelings that gay individuals could possess regarding heterosexuals. Sixty homosexual students were matched with 60 heterosexual psychology students on sex, age, race, and education. Each group was given its respective "phobia" questionnaire. Hypotheses that homosexual participants would report less phobia and more negative experience than heterosexuals and that gay women would report more phobia than gay men were supported. Hypotheses that level of abuse in closeted homosexuals would be positively correlated with phobia scores and that being "out of the closet" would be negatively correlated with phobia scores were not supported.

Adolescent↗
PubMed1998

Increased expression of the differentiation-defective granulocyte colony-stimulating factor receptor mRNA isoform in acute myelogenous leukemia.

Granulocyte colony-stimulating factor (G-CSF) critically affects all stages of granulopoiesis by activating a signaling cascade initiated by dimerization of its receptor (G-CSFR). Five human G-CSFR isoforms have been identified (classes I-V). A quantitative polymerase chain reaction (Q-PCR) technique was used to examine the expression of these five isoforms in normal and leukemic myeloid cells. We demonstrated that neutrophils expressed predominantly the class I isoform and low levels of class IV isoform (IV/I = 0.037 +/- 0.005). No expression of the class II, class III, or class V isoform was detected. In contrast, all AML cell lines and acute myelogenous leukemia (AML) patient samples expressed increased relative amounts of the class IV isoform (IV/I = 0.047-0.350). When compared to normal immature myeloid cells, as represented by the CD34+ fraction of adult bone marrow (ABM) cells, three of eight AML cell lines and three of six AML patient samples expressed significantly increased levels of the class IV isoform relative to class I. This suggests that the increase in the relative expression of the class IV isoform seen in a considerable portion of AML cell samples is related to their leukemic phenotype. Given the inability of the class IV G-CSFR to drive myeloid maturation, the relative increase in class IV expression in AML cells may contribute to their aberrant response to G-CSF.

Adult↗
PubMed1998

Photolocalized varicella in a middle-aged adult.

We report a case of photolocalized varicella occurring in a middle-aged woman. Photolocalized or actinic varicella is rarely described, and most reported cases have occurred in children. This is the first case in a middle-aged adult.

Chickenpox↗