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Biomedical subjects

D J White

Publications and source records attributed to D J White.

At least 19 recordsLinked to original sources
PubMed2001

Penetration of efavirenz into the male genital tract: drug concentrations and antiviral activity in semen and blood of HIV-1-infected men.

Efavirenz is a potent non-nucleoside reverse transcriptase inhibitor, licensed for the treatment of HIV-1. Data on sanctuary site penetration are limited. Therefore, we measured efavirenz concentrations in the blood and semen of 19 HIV-1-positive men and found concentrations in seminal plasma averaged 10% of those in blood plasma. Furthermore, seminal plasma viral loads were suppressed by 24 weeks of therapy in all patients. These data suggest that efavirenz-containing regimens have antiviral activity within the male genital tract.

Alkynes↗
PubMed2001

Identification of the high affinity Mn2+ binding site of bacteriophage lambda phosphoprotein phosphatase: effects of metal ligand mutations on electron paramagnetic resonance spectra and phosphatase activities.

Bacteriophage lambda phosphoprotein phosphatase (lambdaPP) has structural similarity to the mammalian Ser/Thr phosphoprotein phosphatases (PPPs) including the immunosuppressant drug target calcineurin. PPPs possess a conserved active site containing a dinuclear metal cluster, with metal ligands provided by a phosphoesterase motif plus two additional histidine residues at the C-terminus. Multiple sequence alignment of lambdaPP with 28 eubacterial and archeal phosphoesterases identified active site residues from the phosphoesterase motif and in many cases 2 additional C-terminal His metal ligands. Most highly similar to lambdaPP are E. coli PrpA and PrpB. Using the crystal structure of lambdaPP [Voegtli, W. C., et al. (2000) Biochemistry 39, 15365-15374] as a structural and active site model for PPPs and related bacterial phosphoesterases, we have studied mutant forms of lambdaPP reconstituted with Mn(2+) by electron paramagnetic resonance (EPR) spectroscopy, Mn(2+) binding analysis, and phosphatase kinetics. Analysis of Mn(2+)-bound active site mutant lambdaPP proteins shows that H22N, N75H, and H186N mutations decrease phosphatase activity but still allow mononuclear Mn(2+) and [(Mn(2+))(2)] binding. The high affinity Mn(2+) binding site is shown to consist of M2 site ligands H186 and Asn75, but not H22 from the M1 site which is ascribed as the lower affinity site.

Amino Acid Sequence↗
PubMed2001

Expression of complement regulatory proteins on islets of Langerhans: a comparison between human islets and islets isolated from normal and hDAF transgenic pigs.

BACKGROUND: The expression of regulators of complement activity (RCAs) on islet cells may be of great importance for protecting them against complement-mediated lysis in the immediate posttransplant period after intraportal islet transplantation. We examined porcine and human islet cells for expression of RCA. We also examined to what extent human decay accelerating factor (hDAF) is expressed on adult and fetal islet cells isolated from hDAF transgenic (TG) pigs having a high transgene expression on endothelial cells. Moreover, the susceptibility of the various types of cells to lysis in human serum and blood was investigated. METHODS: Adult human islets (n=5), normal adult and fetal porcine islets (n=9 and n=8, respectively), and islets from adult and fetal hDAF TG pigs (n=5 and n=6, respectively) were examined. With islet single-cell suspensions and flow cytometry, adult human islet cells were examined for expression of hDAF (CD55), hCD59, and human membrane cofactor protein (hMCP; CD46), while porcine islet cells were examined for expression of pCD59 and pMCP. Islet cells from hDAF TG pigs were also examined for hDAF expression. Porcine peripheral blood lymphocytes, normal and hDAF TG porcine endothelial cell lines, a human endothelial cell line, and the human cell line U937 served as controls. Islet cytotoxicity was assayed after incubation of the islet cells with fresh human serum. Furthermore, adult islets from normal control pigs and hDAF TG pigs were exposed to fresh human blood in vitro for 60 min, and the inflammatory reaction elicited was compared between the different types of islets. RESULTS: All human islet cell preparations expressed hCD59, two of five expressed hMCP, but none expressed hDAF. Porcine islet cells expressed both pCD59 and pMCP. Normal adult porcine islet cells exposed to fresh human serum resulted in 74+/-5.4% cell lysis (mean+/-SEM, n=16). In comparison, only 1.3+/-2.8% (n=20, P<0.001) of human islet cells were lysed in the human serum. One islet cell preparation from an hDAF TG pig expressed small amounts of hDAF. This preparation from hDAF TG pigs bound significantly less C3c than did normal control islets (mean fluorescence ratio 16+/-2.2 and 58+/-4.3, respectively; P=0.046) and were partially protected from cell lysis in fresh human serum (47+/-10% and 78+/-18% cell lysis, respectively; P=0.046). The other four preparations from hDAF TG pigs were negative for hDAF and were equally susceptible to lysis as normal control islets. All fetal pancreatic islet cells from hDAF TG pigs analyzed were negative for hDAF expression. When exposed to fresh human blood in vitro, adult and fetal islets from hDAF TG pigs elicited equally strong inflammatory changes as did the normal control islets. The inflammatory changes were characterized by activation of the complement and coagulation systems, resulting in islet damage with "dumping" of insulin into the blood. CONCLUSIONS: Porcine and human islet cells express species-restricted complement regulatory proteins, with the human islet cells expressing mainly hCD59. A low expression of hDAF was detected on islet cells from one of five hDAF TG pigs. These islet cells displayed reduced islet cell cytotoxicity in fresh human serum. We conclude that protection from complement-mediated lysis will be important in the context of intraportal pig-to-human islet transplantation, and expression of a human RCA on islet cells should be beneficial in this context.

Animals↗
PubMed2001

Two crystal structures of the cytoplasmic molybdate-binding protein ModG suggest a novel cooperative binding mechanism and provide insights into ligand-binding specificity.

The X-ray structures of the cytoplasmic molybdate-binding protein ModG from Azotobacter vinelandii in two different crystal forms have been determined. For such a small protein it is remarkably complex. Each 14.3 kDa subunit contains two small beta-barrel domains, which display an OB-fold motif, also seen in the related structure of ModE, a molybdenum-dependent transcriptional regulator, and very recently in the Mop protein that, like ModG, has been implicated in molybdenum homeostasis within the cell. In contrast to earlier speculation, the functional unit of ModG is actually not a dimer (as in ModE), but a trimer capable of binding a total of eight molybdate molecules that are distributed between two disparate types of site. All the binding sites are located at subunit interfaces, with one type lying on a crystallographic 3-fold axis, whilst the other lies between pairs of subunits. The two types of site are linked by short hydrogen bond networks that may suggest a cooperative binding mechanism. A superposition of two subunits of the ModG trimer on the apo-ModE dimer allows the probable locations of the molybdate-binding sites of the latter to be assigned. Through structural comparisons with other oxyanion-binding proteins, including Mop and ModE, it is possible to speculate about ligand-binding affinities, selectivity and evolution.

Aldehyde Oxidoreductases↗
PubMed2001

GidA is an FAD-binding protein involved in development of Myxococcus xanthus.

A gene encoding a homologue of the Escherichia coli GidA protein (glucose-inhibited division protein A) lies immediately upstream of aglU, a gene encoding a WD-repeat protein required for motility and development in Myxococcus xanthus. The GidA protein of M. xanthus shares about 48% identity overall with the small (approximately equal to 450 amino acid) form of GidA from eubacteria and about 24% identity overall with the large (approximately equal to 620 amino acid) form of GidA from eubacteria and eukaryotes. Each of these proteins has a conserved dinucleotide-binding motif at the N-terminus. To determine if GidA binds dinucleotide, the M. xanthus gene was expressed with a His6 tag in E. coli cells. Purified rGidA is a yellow protein that absorbs maximally at 374 and 450 nm, consistent with FAD or FMN. Thin-layer chromatography (TLC) showed that rGidA contains an FAD cofactor. Fractionation and immunocytochemical localization show that full length GidA protein is present in the cytoplasm and transported to the periplasm of vegetative-grown M. xanthus cells. In cells that have been starved for nutrients, GidA is found in the cytoplasm. Although GidA lacks an obvious signal sequence, it contains a twin arginine transport (Tat) motif, which is conserved among proteins that bind cofactors in the cytoplasm and are transported to the periplasm as folded proteins. To determine if GidA, like AglU, is involved in motility and development, the gidA gene was disrupted. The gidA- mutant has wild-type gliding motility and initially is able to form fruiting bodies like the wild type when starved for nutrients. However, after several generations, a stable derivative arises, gidA*, which is indistinguishable from the gidA- parent on vegetative medium, but is no longer able to form fruiting bodies. The gidA* mutant releases a heat-stable, protease-resistant, small molecular weight molecule that acts in trans to inhibit aggregation and gene expression of wild-type cells during development.

Amino Acid Sequence↗
PubMed2001

Physiological aspects of pig-to-primate renal xenotransplantation.

BACKGROUND: Few data exist on the physiological aspects of pig-to-primate renal xenotransplantation. METHODS: Use of organs transgenic for human decay accelerating factor has allowed assessment of the metabolic and hormonal functions of these xenografts. RESULTS: Porcine renal xenografts largely maintain plasma electrolyte homeostasis. An increase in proteinuria was detected that may result from graft injury. In contrast to allotransplantation a severe anaemia developed requiring recipient treatment with exogenous human erythropoietin. CONCLUSIONS: Our experience provides qualified encouragement for the likely physiological compatibility of pig and primate species, but identifies areas where a xenograft may not match the performance of an allograft.

Anemia↗
PubMed2001

Antiretroviral drug concentrations in semen of HIV-infected men: differential penetration of indinavir, ritonavir and saquinavir.

Variable drug penetration of antiretroviral drugs into the genital tract may contribute to the differential evolution of HIV and the emergence of drug resistance. This, in turn, may have an impact on the sexual transmission of resistant HIV in patients treated with antiretroviral drugs. We have measured concentrations of the HIV-1 protease inhibitors indinavir, ritonavir and saquinavir in the blood plasma (BP) and seminal plasma (SP) of 23 HIV-1-positive men. Forty-five time-matched blood and semen samples were obtained. SP concentrations of indinavir exceeded the EC95 of indinavir, corrected for protein binding, of 42 ng/mL at all time intervals. In contrast, the median ritonavir and saquinavir SP concentrations were below the relevant EC95 at all times post drug ingestion. The median SP:BP concentration ratios for indinavir were 0.6, 0.8 and 1.4, respectively, at 0-2, 2-6 and 6-8 h post-drug ingestion. In contrast, the median SP:BP concentration ratios at 0-3, 3-9 and 9-12 h post-drug ingestion were <0.02, <0.04 and <0.04, respectively, for both ritonavir and saquinavir. These differences justify further study of HIV-1 evolution and development of resistance in the genital tract of men taking these anti-HIV drugs.

Adult↗
PubMed2001

Antioxidant vitamin therapy alters burn trauma-mediated cardiac NF-kappaB activation and cardiomyocyte cytokine secretion.

BACKGROUND: This study examined the effects of antioxidant vitamins A, C, and E on nuclear transcription factor-kappa B (NF-kappaB) nuclear translocation, on secretion of inflammatory cytokines by cardiac myocytes, and on cardiac function after major burn trauma. METHODS: Adult rats were divided into four experimental groups: group I, shams; group II, shams given oral antioxidant vitamins (vitamin C, 38 mg/kg; vitamin E, 27 U/kg; vitamin A, 41 U/kg 24 hours before and immediately after burn); group III, burns (third-degree scald burn over 40% total body surface area) given lactated Ringer's solution (4 mL/kg/% burn); and group IV, burns given lactated Ringer's solution plus vitamins as described above. Hearts were collected 4, 8, 12, and 24 hours after burn to assay for NF-kappaB nuclear translocation, and hearts collected 24 hours after burn were examined for cardiac contractile function or tumor necrosis factor-alpha secretion by cardiomyocytes. RESULTS: Compared with shams, left ventricular pressure was lower in burns given lactated Ringer's solution (group III) (88 +/- 3 vs. 64 +/- 5 mm Hg, p < 0.01) as was +dP/dt max (2,190 +/- 30 vs. 1,321 +/- 122 mm Hg/s) and -dP/dt max (1,775 +/- 71 vs. 999 +/- 96 mm Hg, p < 0.01). Burn injury in the absence of vitamin therapy (group III) produced cardiac NF-kappaB nuclear migration 4 hours after burn and cardiomyocyte secretion of tumor necrosis factor-alpha, interleukin-1beta, and interleukin-6 by 24 hours after burn. Antioxidant therapy in burns (group IV) improved cardiac function, producing left ventricular pressure and +/-dP/dt (82 +/- 2 mm Hg, 1,880 +/- 44 mm Hg, and 1,570 +/- 46 mm Hg/s) comparable to those measured in shams. Antioxidant vitamins in burns inhibited NF-kappaB nuclear migration at all times after burn and reduced burn-mediated cytokine secretion by cardiomyocytes. CONCLUSION: These data suggest that antioxidant vitamin therapy in burn trauma provides cardioprotection, at least in part, by inhibiting translocation of the transcription factor NF-kappaB and interrupting cardiac inflammatory cytokine secretion.

Animals↗
PubMed2001

West Nile virus: a case study in how NY State Health Information infrastructure facilitates preparation and response to disease outbreaks.

New York's (NY) Health Information Network (HIN) provided timely access to West Nile Virus (WNV) data during the initial outbreak in the late Summer 1999. In December 1999, NY developed a plan to deal with WNV in 2000 that required an integrated surveillance system for humans, birds, mammals, and mosquitoes. The HIN infrastructure allowed NY to deploy this system statewide in three months. Local health departments throughout NY used the system to report, track, and retrieve surveillance data as WNV spread throughout NY in 2000. The HIN infrastructure includes partnerships, training/support, technical capacity and architecture similar to NEDSS as proposed by the US CDC.

Animals↗
PubMed2001

Vector surveillance for West Nile virus.

West Nile virus (WNV) was detected in the metropolitan New York City (NYC) area during the summer and fall of 1999. Sixty-two human cases, including seven fatalities, were documented. The New York State Department of Health (NYSDOH) initiated and implemented a statewide mosquito and WNV surveillance system. We developed a WNV response plan designed to provide local health departments (LHD) a standardized means to begin to assess basic mosquito population data and to detect WNV circulation in mosquito populations. During the 2000 arbovirus surveillance season, local health agencies collected 317,676 mosquitoes and submitted 9,952 pools for virus testing. NYSDOH polymerase chain reaction (PCR) testing detected 363 WNV-positive pools. Eight species of mosquitoes were found to be infected. Of the 26 counties conducting mosquito surveillance, WNV-positive mosquitoes were detected only in NYC, on Long Island, and in four counties in the lower Hudson River valley region. LHD larval surveillance provided initial or enhanced mosquito habitat location and characterization and mosquito species documentation. Adult mosquito surveillance provided LHD information on species' presence, density, seasonal fluctuations, virus infection, minimum infection ratios (MIR) and indirect data on mosquito control efficacy after larval or adult control interventions. Collective surveillance activities conducted during 1999 and 2000 suggest that WNV has dispersed throughout the state and may affect local health jurisdictions within NYS, adjacent states, and Canada in future years. Vector surveillance will remain a critical component of LHD programs addressing public health concerns related to WNV.

Animals↗
PubMed2001

Combined topical flucytosine and amphotericin B for refractory vaginal Candida glabrata infections.

Patients with vaginitis due to highly azole resistant Candida glabrata can be particularly difficult to treat. We describe three cases of longstanding vaginal candidiasis due to C glabrata. These had failed to respond to local and systemic antifungals. Flucytosine (1 g) and amphotericin B (100 mg) formulated in lubricating jelly base in a total 8 g delivered dose, was used per vagina once daily for 14 days with significant improvement, both clinically and microbiologically.

Adult↗
PubMed2001

Overexpression of cardiac I-kappaBalpha prevents endotoxin-induced myocardial dysfunction.

Nuclear factor-kappa B (NF-kappaB) is an inducible transcription factor that regulates expression of many genes, such as tumor necrosis factor-alpha (TNF-alpha), which may contribute to myocardial dysfunction. We investigated whether cardiac NF-kappaB activation is involved in the development of myocardial dysfunction after lipopolysaccharide (LPS) challenge. Mice were intraperitoneally injected with LPS, and the hearts were harvested and assayed for NF-kappaB translocation. After LPS challenge, NF-kappaB activation was detected within 30 min and remained for 8 h. In transgenic mice constitutively overexpressing a nondegradable form of I-kappaBalpha (I-kappaBalphaDeltaN) in cardiomyocytes, myocardial NF-kappaB translocation was prevented after LPS challenge. Myocytes isolated from these transgenics secreted significantly less TNF-alpha than did wild-type cardiomyocytes after LPS stimulation. When whole hearts were excised, perfused in a Langendorff preparation, and challenged with endotoxin, I-kappaBalphaDeltaN transgenic hearts displayed normal cardiac function, whereas profound contractile dysfunction was observed in wild-type hearts. These data indicate that myocardial NF-kappaB translocates within minutes after LPS administration. Inhibition of myocyte NF-kappaB activation by overexpression of myocyte I-kappaBalpha is sufficient to block cardiac TNF-alpha production and prevent cardiac dysfunction after LPS challenge.

Animals↗
PubMed2001

Targeted disruption of ICAM-1, P-selectin genes improves cardiac function and survival in TNF-alpha transgenic mice.

We have developed a transgenic mouse model in which tumor necrosis factor (TNF)-alpha is overexpressed exclusively in the heart under the regulation of the alpha-myosin heavy chain promoter. These animals develop chronic heart failure associated with severe leukocyte infiltration in both the atria and the ventricles. The purpose of this study was to investigate the role of adhesion molecules in mediating cardiac dysfunction in the TNF-alpha transgenic model. TNF-alpha transgenic mice were bred with mice null for intercellular adhesion molecule (ICAM)-1 and P-selectin genes to obtain a lineage of ICAM-1 and P-selectin null mice with selective overexpression of TNF-alpha in the heart. TNF-alpha transgenic animals showed marked upregulation of ICAM-1 mRNA and protein; however, P-selectin mRNA and protein remained undetectable despite chronic TNF overexpression. Cardiac function was markedly improved in the ICAM-1(-/-), P-selectin(-/-), TNF-alpha transgenic group versus the ICAM(+/+), P-selectin(+/+), TNF-alpha transgenic group. Kaplan-Meier survival curves showed statistically significant prolonged survival in the ICAM-1(-/-), P-selectin(-/-), TNF-alpha transgenic animals. These data suggest that ICAM-1 mediates at least in part the cardiac dysfunction induced by TNF-alpha expression by cardiac myocytes.

Animals↗
PubMed2001

Role of p38 mitogen-activated protein kinase in cardiac myocyte secretion of the inflammatory cytokine TNF-alpha.

This study examined the hypothesis that burn trauma promotes cardiac myocyte secretion of inflammatory cytokines such as tumor necrosis factor (TNF)-alpha and produces cardiac contractile dysfunction via the p38 mitogen-activated protein kinase (MAPK) pathway. Sprague-Dawley rats were divided into four groups: 1) sham burn rats given anesthesia alone, 2) sham burn rats given the p38 MAPK inhibitor SB203580 (6 mg/kg po, 15 min; 6- and 22-h postburn), 3) rats given third-degree burns over 40% total body surface area and treated with vehicle (1 ml of saline) plus lactated Ringer solution for resuscitation (4 ml x kg(-1). percent burn(-1)), and 4) burn rats given injury and fluid resuscitation plus SB203580. Rats from each group were killed at several times postburn to examine p38 MAPK activity (by Western blot analysis or in vitro kinase assay); myocardial function and myocyte secretion of TNF-alpha were examined at 24-h postburn. These studies showed significant activation of p38 MAPK at 1-, 2-, and 4-h postburn compared with time-matched shams. Burn trauma impaired cardiac mechanical performance and promoted myocyte secretion of TNF-alpha. SB203580 inhibited p38 MAPK activity, reduced myocyte secretion of TNF-alpha, and prevented burn-mediated cardiac deficits. These data suggest p38 MAPK activation is one aspect of the signaling cascade that culminates in postburn secretion of TNF-alpha and contributes to postburn cardiac dysfunction.

Animals↗
PubMed2001

Lyme disease in New York State: spatial pattern at a regional scale.

Lyme disease occurs commonly in New York State, but its geographic distribution is heterogeneous. Over each of nine consecutive years, incidence rates from 57 New York State counties were subjected to spatial autocorrelation analysis. Although the epidemic advanced during the study period, the analyses reveal a consistent pattern of spatial dependence. The correlation distance, the distance over which incidence rates covary positively, remained near 120 km over the nine years. A local spatial analysis around Westchester County, a major disease focus, indicated that the global correlation distance matched the extent of the most intense local clustering; statistically weaker clustering extended to 200 km from Westchester. Analyzing the spatial character of the epidemic may reveal the epizootic processes underlying patterns in human infection, and may help identify a spatial scale for regional control of disease.

Humans↗
PubMed2001

Anticaries profile qualification of an improved whitening dentifrice.

A series of pH cycling "profile" laboratory studies was conducted to confirm the anticaries potential of an enhanced cleaning and whitening dentifrice based on a novel abrasive polishing silica and pyrophosphate tartar control source, with sodium fluoride as the anticaries ingredient. Under pH cycling remineralization conditions, the whitening dentifrice produced lesion fluoridation comparable to a conventional tartar control dentifrice containing combinations of pyrophosphate anion and a NaF fluoride ion source. Under pH cycling lesion progression conditions, the whitening dentifrice produced enamel protection against caries development, comparable to control dentifrices containing NaF alone or in combination with tartar control pyrophosphate anion. These results are consistent with clinical data supporting the effectiveness of NaF dentifrices combined with anionic tartar control inhibitors such as pyrophosphate. These results support the anticaries effectiveness of the enhanced cleaning and whitening dentifrice based upon "Stain-Specific Soft Silica."

Analysis of Variance↗