Inhaled furosemide attenuates hyperpnea-induced obstruction and intra-airway thermal gradients

Inhaled furosemide attenuates exercise- and isocapnic hyperventilation-induced asthma; however, the mechanism for this phenomenon is unknown. Because the magnitude of the intra-airway thermal gradient that develops between the cooling of hyperpnea and the rewarming that occurs once hyperventilation ceases is directly related to the severity of thermally induced obstruction in humans, we wondered if furosemide blunted these temperature changes. To explore this issue, eight asthmatic subjects had tracheobronchial airstream temperature measures as they performed isocapnic hyperventilation with frigid air alone (HV) or with pretreatment with inhaled saline (S + HV) or 45 +/- 3 (SE) mg of furosemide (F + HV). HV and S + HV resulted in similar degrees of obstruction, whereas the mechanical decrements after F + HV were significantly less. In concert with this protective effect, F + HV resulted in less airstream cooling during hyperventilation and slower rewarming in the recovery period. Because the major source of heat to the airways is provided by its microcirculation, inhaled furosemide may be acting as a topical vasodilator serving to enhance heat availability and thus reducing the effective thermal burden of hyperpnea.

Correlates of physical activity at home in Mexican-American and Anglo-American preschool children

Twenty-two potential correlates of children's physical activity were examined. Two hundred and one Mexican-American and 146 Anglo-American families with 4-year-old children were studied. Children's physical activity was directly observed in the evening at home on 4 visits for 1 hr each time. Anglo-American children and male children were found to be more active. Demographic variables explained 11% of the variance in children's physical activity. After adjusting for demographics, 3 children's variables and 6 social-family variables did not account for significantly more variance. Five environmental variables accounted for 11% additional variance. Variables observed concurrently with physical activity, such as time spent outdoors and prompts to be active, were highly associated with children's physical activity.

Human cytomegalovirus IE86 protein interacts with promoter-bound TATA-binding protein via a specific region distinct from the autorepression domain

The major immediate-early gene of human cytomegalovirus encodes several isoforms of an immediate-early protein which has distinct transcriptional regulatory properties. The IE86 isoform autorepresses the major immediate-early promoter by directly binding the cis repression signal element located between the TATA box and the mRNA cap site. In addition to this activity, IE86 stimulates other viral and cellular promoters. One mechanism by which eukaryotic regulatory proteins are thought to stimulate transcription is by contacting one or more general transcription factors. We show that the IE86 protein physically interacts with the DNA-binding subunit (TATA-binding protein) human transcription factor IID via the TATA-binding protein-contacting domain in the N terminus of IE86. In a mobility shift assay, IE86 was also observed to stabilize the binding of TATA-binding protein to promoter DNA. The domains within IE86 responsible for mediating transactivation and repression functioned independently. These experiments thus demonstrate the elegant ability of human cytomegalovirus to join different protein domains to produce distinct multifunctional proteins.

Site-specific inhibition of RNA polymerase II preinitiation complex assembly by human cytomegalovirus IE86 protein

The human cytomegalovirus major immediate-early gene encodes several protein isoforms which autoregulate the major immediate-early promoter (MIEP). One of these isoforms, the IE86 protein (UL122, IE2), is a DNA-binding protein that represses the MIEP through its cognate recognition sequence (designated the cis repression signal [crs]) located between the TATA box and the initiation site of transcription. Purified recombinant IE86 protein was shown to repress MIEP transcription in vitro, in a cis-acting mediated pathway, with nuclear extracts from HeLa S3, U373-MG, and primary human foreskin fibroblast cells. Repression of the MIEP by IE86 was shown by two criteria to be dependent on the direct interaction of IE86 with the crs element. Core promoter constructs containing essentially the MIEP TATA box and crs element were also specifically repressed by IE86 but not by a mutant IE86 protein, indicating the general transcription machinery as the target for IE86 repression. Kinetic and template commitment experiments demonstrated that IE86 affects preinitiation complex formation but not the rate of reinitiation. Sarkosyl inhibition experiments further revealed that IE86 was unable to effect repression by either disassembling or preventing the elongation of a preexisting transcription complex. Further, the ability of IE86 to interact with the DNA-binding subunit of TFIID was shown not to be required for repression. These functional protein-DNA and protein-protein interaction experiments demonstrate that IE86 specifically interferes with the assembly of RNA polymerase II preinitiation complexes. The biological significance of these results and the precise mechanism by which IE86 represses transcription are discussed.

Human immunodeficiency virus infection of human brain capillary endothelial cells occurs via a CD4/galactosylceramide-independent mechanism

Neuropathologic studies of AIDS patients have shown that brain capillary endothelial cells are a cellular target for human immunodeficiency virus (HIV) in vivo. We have established in vitro cultures of primary human brain capillary endothelial (HBCE) cells. Using this model system, we have shown a significant HIV infection of HBCE cells that is productive yet noncytopathic. The infection is mediated by a cellular interaction with gp120 that does not involve CD4 or galactosylceramide. HIV infection of HBCE cells may contribute to AIDS-associated neuropathology by disturbing the physiology of the endothelium and directly or indirectly facilitating dissemination of virus to the central nervous system.

Phloridzin and phloretin inhibition of 2-deoxy-D-glucose uptake by tumor cells in vitro and in vivo

Utilizing the rat mammary adenocarcinoma and Fischer bladder cell carcinoma cell lines, this study demonstrated the ability of two known glucose transport inhibitors, phloridzin (P1) and its aglucone, phloretin (P2), to block glucose transport into whole viable tumor cells in vitro and tumor tissues in vivo. This work represents the first in a series of experiments designed to explore the efficacy of P1 and P2 administration in restraining tumor cell growth via the inhibition of glucose transmembrane transport.

The efficacy of phloridzin and phloretin on tumor cell growth

This study utilized phloridzin (P1) and its aglucone phloretin (P2), two known inhibitors of glucose transmembrane transport, to inhibit tumor cell growth in vivo. The efficacy of hydrazine sulfate as an anticachexic agent was also evaluated. Utilizing the rat mammary adenocarcinoma and Fischer bladder cell carcinoma cell lines, it has been shown that the i.p. administration of P1 and P2 can produce significant differences in mean tumor diameters as compared to the untreated controls.

Pharmaceutical properties, biodistribution, and imaging characteristics of manganese-mesoporphyrin. A potential hepatobiliary contrast agent for magnetic resonance imaging

OBJECTIVES

Manganese (III) mesoporphyrin (Mn-mesoporphyrin) was investigated for its pharmaceutical properties and magnetic resonance imaging characteristics as a potential hepatobiliary contrast agent.

METHODS

Solubility, partition coefficient, plasma binding, proton relaxation enhancement, biodistribution, biliary excretion, liver extraction ratio, and liver enhancement were measured in various in-vitro and in-vivo systems.

RESULTS

Mn-mesoporphyrin was soluble and stable at moderate alkaline pH in phosphate buffer. The octanol/water coefficient was 25.98, and the compound was highly protein bound. R1 for water and plasma were 1.94 and 2.35 L/mmol sec, respectively. R1 in liver was calculated to be 15.72 L/mmol sec. Biodistribution studies in rats and mice confirmed hepatotrophic properties and biliary excretion was 65% over 24 hours. First pass liver uptake was 15%. Magnetic resonance imaging studies showed persistent liver enhancement at 0.05 mmol/kg.

CONCLUSION

Mn-mesoporphyrin is a lipophilic compound that shows potential as a hepatobiliary magnetic resonance contrast agent.

Direct interaction of the human cytomegalovirus IE86 protein with the cis repression signal does not preclude TBP from binding to the TATA box

The human cytomegalovirus major immediate-early gene encodes several protein isoforms which autoregulate the major immediate-early promoter (MIEP). One of these isoforms, the IE86 protein, represses the MIEP through a DNA sequence located between the TATA box and the transcription initiation site, designated the cis repression signal (crs). Through mutational analysis, amino acid domains within IE86 responsible for binding the crs element were located at the C terminus. Mutation of the putative zinc finger domain, which precluded IE86 from binding DNA, converted the protein from a repressor of MIEP transcription into an activator. DNase I protection analysis demonstrated that the IE86 footprint overlapped the sequence protected by the TATA-binding protein (TBP). Investigation of whether IE86 was able to displace TBP from DNA revealed that both proteins could bind DNA simultaneously. However, higher concentrations of IE86 were required to obtain protection of the crs element in the presence of prebound TBP. Similarly, higher concentrations of TBP were required to obtain protection in the presence of prebound IE86. These observations indicate that steric hinderance impairs but does not prevent both proteins from binding DNA synchronously.

Correlates of physical activity at home in Mexican-American and Anglo-American preschool children

Twenty-two potential correlates of children's physical activity were examined. Two hundred and one Mexican-American and 146 Anglo-American families with 4-year-old children were studied. Children's physical activity was directly observed in the evening at home on 4 visits for 1 hr each time. Anglo-American children and male children were found to be more active. Demographic variables explained 11% of the variance in children's physical activity. After adjusting for demographics, 3 children's variables and 6 social-family variables did not account for significantly more variance. Five environmental variables accounted for 11% additional variance. Variables observed concurrently with physical activity, such as time spent outdoors and prompts to be active, were highly associated with children's physical activity.

The DNA-binding subunit of human transcription factor IID can interact with the TATA box as a multimer

Transcription initiation from eukaryotic protein-coding genes is a complex process that minimally requires RNA polymerase (pol) II (B) and at least seven general transcription factors. The 38-kDa subunit (TBP) of the human general transcription factor TFIID recognizes the TATA sequence element and initiates the assembly of the other general transcription factors and RNA pol II. It is believed, based on experiments with yeast recombinant protein, that TBP binds as a monomer to DNA. Using purified recombinant human TBP protein we find that TBP interacts with the TATA element as both a monomer and a dimer. The multimeric binding of TBP to DNA revealed by this study has important implications for the role of TBP in transcription initiation and suggests novel mechanisms whereby other transcription factors may interact with a RNA pol II preinitiation complex.

In vitro susceptibility of Borrelia burgdorferi to 11 antimicrobial agents

The in vitro susceptibility of Borrelia burgdorferi to 11 antimicrobial agents was investigated. The antimicrobial agents evaluated included ceftizoxime, FK037, cefotaxime, dirithromycin, clarithromycin and its metabolite 14-hydroxy-clarithromycin, erythromycin, doxycycline, amoxicillin, ciprofloxacin, and ofloxacin. Isolates of B. burgdorferi tested included two reference strains (B31 and ATCC 53899), six isolates from the midwestern United States, and three from Europe. A broth macrodilution method was used to determine MICs and MBCs. B. burgdorferi was inhibited by < or = 0.5 micrograms of each of the agents except the quinolones per ml. The MBCs for 90% of strains tested of ceftizoxime, FK037, clarithromycin, 14-OH clarithromycin, and dirithromycin (< or = 1.0 microgram of each per ml) were superior to those of amoxicillin (2.0 micrograms/ml) and doxycycline (4.0 micrograms/ml). Further in vivo studies are warranted to determine whether these agents may be efficacious in the treatment of Lyme borreliosis.

Animal model of portal hypertension with observations regarding the relationship between portal flow and pressure

RATIONALE AND OBJECTIVES

The feasibility of producing acute portal hypertension in a porcine model was evaluated to test the relationship between portosystemic shunt flow and portal pressure.

METHODS

Percutaneous transhepatic cannulation of the portal vein and cutdown of a systemic vein was accomplished in anesthetized pigs. The portal system was subsequently embolized with polyvinyl alcohol (Ivalon) particles. Portosystemic shunting was performed with the assistance of a centrifugal pump.

RESULTS

Portal hypertension could be routinely produced, and portosystemic shunting was successfully studied in three of four animals. Linear changes in shunt flow led to exponential pressure changes.

CONCLUSIONS

This animal model provides a representation of acute portal hypertension that provides useful data regarding the compliance of the portal system and illustrates the pressure/flow relationship.

Coexpression of truncated human cytomegalovirus gH with the UL115 gene product or the truncated human fibroblast growth factor receptor results in transport of gH to the cell surface

The gH glycoprotein of herpesviruses is located on the cell surface in viral-infected cells but is retained in the endoplasmic reticulum (ER) when expressed separately from a recombinant expression vector. These observations suggested the requirement for either a viral function or a viral-induced cellular function which facilitates surface expression of gH. gL fulfills this role in the herpes simplex virus (HSV)-infected cell (J. Virol. 66, 2240-2250, 1992). We have identified the gene product of the UL 115 open reading frame (ORF) as the functional homologue of HSV gL in the human cytomegalovirus (CMV) genome. In addition, we have demonstrated that a cellular gene, the human basic fibroblast growth factor receptor (FGFr) will also facilitate some transport of CMV gH to the cell surface. Coexpression in Chinese hamster ovary cells of the gene product of the UL115 ORF or soluble FGFr with C-terminally truncated gH enhanced levels of secreted gH. These studies suggest that the coexpressed molecules act to mask an ER retention signal(s) exposed when recombinant gH is expressed outside of the context of the viral-infected cell.

Peroxide bleaches: effect on tensile strength of composite resins

Research concerning bleaching agents on the mechanical properties of composite resin restorative materials has produced conflicting reports. Representative brands of composite resin restorative materials were studied, including microfil, hybrid, and posterior types. The bleaching agents selected were 30% hydrogen peroxide and two commercial brands of 10% carbamide peroxide. Ten specimens of each material, prepared according to American National Standards Institute/American Dental Association specification No. 27 for diametral tensile testing, were stored in bleaching agents for 1 hour and 168 hours at 37 degrees C. An equal number of specimens stored in deionized water with identical conditions were designated controls. Qualitative examination of bleached specimens revealed a marked change in color, especially the microfilled composite resins. There was no significant difference in tensile strength between controls and exposed samples at either time except for the diminished strength of microfilled composite resins in 30% hydrogen peroxide for one week (p < 0.01).

Vascular volume expansion and thermally induced asthma

To determine whether a relationship exists between intravenous infusion of isotonic fluid and reactivity to hyperpnoea, eight normal and eight asthmatic subjects underwent rapid intravascular administration of approximately 2 l of warm normal saline, by itself and before and after hyperventilation of cold air. In the asthmatic subjects, saline infusion mirrored the obstruction seen with hyperventilation; whereas, in normal subjects saline produced more bronchial narrowing than hyperventilation. When the two stimuli were given together, the timing of the infusion altered the asthmatic subjects' responses. Giving fluid early in the hyperventilation challenge blunted obstruction, whereas giving it later amplified the airway narrowing. Similar findings, but on a smaller scale, occurred in normal subjects. These data demonstrate that sudden elevations in intrathoracic vascular volume with warm saline produce airway obstruction that is quantitatively similar to that seen with hyperventilation in asthmatic individuals. They also demonstrate that these two stimuli interact together in such a manner that a common mechanism may exist to account for the decrease in airflow.

Vascular volume expansion and thermally induced asthma

To determine whether a relationship exists between intravenous infusion of isotonic fluid and reactivity to hyperpnoea, eight normal and eight asthmatic subjects underwent rapid intravascular administration of approximately 2 l of warm normal saline, by itself and before and after hyperventilation of cold air. In the asthmatic subjects, saline infusion mirrored the obstruction seen with hyperventilation; whereas, in normal subjects saline produced more bronchial narrowing than hyperventilation. When the two stimuli were given together, the timing of the infusion altered the asthmatic subjects' responses. Giving fluid early in the hyperventilation challenge blunted obstruction, whereas giving it later amplified the airway narrowing. Similar findings, but on a smaller scale, occurred in normal subjects. These data demonstrate that sudden elevations in intrathoracic vascular volume with warm saline produce airway obstruction that is quantitatively similar to that seen with hyperventilation in asthmatic individuals. They also demonstrate that these two stimuli interact together in such a manner that a common mechanism may exist to account for the decrease in airflow.

Seven-day recall and other physical activity self-reports in children and adolescents

There is need to develop low cost, practical, and accurate measures of physical activity in children and adolescents, and self-report is a promising methodology for children that is applicable for large studies. The purpose of the present study was to assess the reliability and validity of several self-reports of physical activity. Subjects were 36 fifth-, 36 eighth-, and 30 eleventh-grade male and female students. The test-retest reliabilities were r = 0.77 for the 7-d recall interview, r = 0.81 for the Godin-Shephard self-administered survey, and r = 0.93 for a simple activity rating. For the former two measures, reliability improved with age but was significant at all ages, and for the last measure there were no age effects. Memory skills and obesity status were not related to the reliability of recall, but males were more reliable reporters than females. Validity of the 7-d recall was determined by comparing heart rate monitoring records with recalls of very hard activities on the same day. A correlation of 0.53 (P < 0.001) for the total group supported the validity of the reports. Validity improved with age, but validity coefficients were significant in all age groups. These data indicate that physical activity recalls of children as young as the fifth grade are of adequate reliability and validity to use in research on physical activity in children.

Antibody profiles to the group B streptococcal beta antigen in maternal and infant paired sera

Antibody profiles to the purified beta antigen of the c protein of group B streptococci (GBS) were studied by ELISA and Western immunoblot (WB). The sera from 139 parturient women colonized with GBS, 35 non-colonized parturients and their newborn infants were studied by ELISA; WB was done on 76 maternal and 26 infant sera. Enzyme-labeled anti-IgA (alpha), -IgG (gamma), -IgM (mu), or -IgG (H&L) were used as secondary antibodies. A high prevalence of antibody to the beta antigen was observed by both ELISA and WB among parturient women and their newborns. IgG (H&L) ELISA titers > or = 200 were found in 84% and > or = 800 in 31% of the maternal sera. A significantly higher percentage of women colonized than those non-colonized with GBS had IgG (gamma) titers > or = 800. A significantly higher percentage of women colonized with c protein-positive than c-negative strains of GBS had IgG (H&L) titers > or = 3200. Twelve of 27 women with IgM antibody to the beta antigen also had IgG (gamma) titers > or = 800 and were, in addition, colonized with GBS. Multiple molecular forms of the antigen from 25 to 140 kDa were blotted by the maternal and infant sera. Concordance in the IgG but not in IgA or IgM antibody profiles of maternal and infant paired sera was observed in the overall blotting patterns and ELISA titers. The same titer as the mother was found in 55% of the infant sera and within one dilution in 97%. This suggests active transfer of IgG antibody to the beta antigen across the placenta from mother to baby.

Plasmodium falciparum: cytoadherence of malaria-infected erythrocytes to human brain capillary and umbilical vein endothelial cells--a comparative study of adhesive ligands

The cytoadherence of Plasmodium falciparum-infected erythrocytes (FCR-3 line) to human brain capillary endothelial cells (HBEC), C32 amelanotic melanoma cells, and human umbilical vein endothelial cells (HUVEC) was studied. The adhesion of infected red cells was HBEC > amelanotic melanoma > HUVEC. The presence or absence of the adhesive ligands ICAM-1 (CD54 or intercellular adhesion molecule 1), ICAM-2, and CD36 (= glycoprotein IV) was determined for each of these cells by indirect immunofluorescence using the monoclonal antibodies RR1/1, 6D5, and OKM 5/OKM 8, respectively. It appeared that a major ligand for the FCR-3 line of P. falciparum with amelanotic melanoma cells and HBECs was CD36. Binding to HUVECs was very low, presumably due to their lack of expression of CD36. HBECs, because of their ease of in vitro propagation, long-term maintenance of cytoadherent properties, and their high degree of adhesiveness, will be useful for in vitro studies of adherence.

Consequences of 6-thioguanine incorporation into DNA on polymerase, ligase, and endonuclease reactions

The incorporation of 6-thioguanine (S6G) in place of guanine proceeds readily in DNA synthesis reactions catalyzed by mammalian and bacterial polymerases. This report summarizes the consequences of such incorporation studied to date. S6G was incorporated into one strand of a defined M13mp18 phage sequence in a (+)reaction catalyzed by the Klenow fragment of Escherichia coli DNA polymerase I. After denaturation of the newly synthesized strand (containing S6G) and annealing with a reverse (-) 32P-labeled primer, polymerization catalyzed by the Klenow enzyme as well as by human DNA polymerases alpha, gamma, and delta was slowed considerably, compared with that across the corresponding guanine-containing template. To evaluate S6G-containing DNA as a substrate for DNA ligases, two oligodeoxynucleotides (19- and 20-mers) antisense to a 40-mer were synthesized so that the 40-mer coded for guanine at the 3' terminus of the 19-mer. After annealing of the synthetic oligonucleotides to form a duplex DNA containing a one-nucleotide gap (opposite cytosine in the 40-mer), the 19-mer was extended with 2'-deoxythioguanosine 5'-triphosphate using DNA polymerase, forming a nicked duplex DNA. The abilities of T4 DNA ligase and HeLa and calf thymus DNA ligase I to join the 5'-phosphate with the 3'-S6G-OH were severely inhibited, compared with the 3'-guanine-extended control. This finding suggests that incorporation of S6G at the 3' terminus of Okazaki fragments would inhibit lagging strand DNA synthesis. In other experiments, cleavage of S6G-containing DNA by some but not all restriction endonucleases progressed poorly, compared with the control guanine-containing DNA, independently of the location of S6G at recognition or cleavage sites, as previously observed by Iwaniec et al. [Mol. Pharmacol. 39:299-306 (1991)] with a different spectrum of enzymes. These findings indicate altered DNA-protein interactions due to S6G incorporation. The poor template function of S6G-containing DNA is consistent with the known delayed cytotoxicity and DNA damage previously reported to occur in S6G-treated cells.

The composite resin-amalgam window preparation

Amalgam restorations with a very visible mesiofacial aspect can be aesthetically modified. Clinical experience has proven the amalgam window preparation to be an economical, expedient, and effective treatment approach when patients request tooth-colored fillings in posterior maxillary teeth.

Hepatic contrast-enhancing properties of manganese-mesoporphyrin and manganese-TPPS4. A comparative magnetic resonance imaging study in rats

OBJECTIVES

Manganese (III) mesoporphyrin (Mn-mesoporphyrin), a synthetic and stable complex, was investigated for its hepatic magnetic resonance imaging (MRI) properties and compared with manganese tetrakis-(4 sulfonatophenyl) porphyrin (Mn-TPPS4).

METHODS

Liver abscesses (n = 10) and tumors (n = 14) were induced in rats. These rats then underwent MRI at 2.0 T. Animals received one of the two contrast agents, and measurement of lesion enhancement was performed.

RESULTS

At an intravenous dose of 0.035 mmol/kg, Mn-mesoporphyrin caused significant enhancement of normal liver parenchyma and increased the lesion-to-liver contrast in both the models of heptic liver abscess and metastatic liver disease. Mn-TTPS4 at an intravenous dose of 0.04 mmol/kg typically enhanced both lesion and normal liver parenchyma and therefore did not improve the lesion-to-liver contrast.

CONCLUSIONS

The hepatotrophic properties of Mn-mesoporphyrin indicate its potential as an intravenous contrast agent for liver imaging.

An isoform variant of the cytomegalovirus immediate-early auto repressor functions as a transcriptional activator

The major immediate-early promoter (MIEP) of human cytomegalovirus directs the expression of several differentially spliced and polyadenylated mRNAs. These mRNAs encode nuclear phosphorproteins (IE55, IE72, and IE86), which consist of common and unique amino acid sequences. To date, very little is known of the functional role of the 55-kDa (IE55) protein. Here we present evidence that the IE55 protein is a positive activator of the MIEP. In human fibroblast cells IE55 protein activated the MIEP between 10- and 30-fold. Fusion of IE55 to the GAL4 DNA binding domain resulted in a chimeric protein capable of trans-activating a reporter with GAL4 recognition sequences. These results strongly suggest that IE55 is a bona fide transcriptional activator protein. In addition, the IE55 protein was found not to act synergistically with the IE72 activator protein. The IE55 protein shares the same amino acid sequence as IE86 except for a 154-amino-acid deletion at the C-terminal end of the protein. These proteins were functionally antagonistic; IE55 relieved repression by IE86 and, conversely, IE86 negated IE55 activation. Mutagenesis of the MIEP revealed that the target sequence for activation by IE55 is different from the IE86 autorepressive response element. These experiments suggest that the mechanism of action of the IE55 and IE86 isoforms is distinct. Moreover, from these results it is apparent that the interplay of these factors might be critical in determining the level of HCMV replication in the host.

Infant-feeding practices and adiposity in 4-y-old Anglo- and Mexican-Americans

A longer duration of breast-feeding and later introduction to solids may protect against excessive adiposity in infancy. This study investigated infant feeding practices and their relationship to two measures of adiposity--body mass index (BMI) and sum of skinfold thicknesses (SUMSF)--in 331 4-y-old Anglo- (43%) and Mexican-American (57%) children. No associations were detected between any of the infant feeding variables of duration of breast-feeding and introduction to solids and formula and measures of the child's adiposity. Mother's physical measures of BMI and SUMSF explained the largest portion of variance for both measures of childhood adiposity, BMI (9.5%), and SUMSF (8.3%). Genetic and environmental factors other than infant feeding practices appear to have a greater influence on a 4-y-olds' adiposity.

Postnatal development of organic cation transport and mdr gene expression in mouse kidney

The apical surface of the proximal tubular epithelium is the site of both P-glycoprotein localization and postulated active secretion of organic cations in the mammalian kidney. P-glycoprotein has been shown to act as a pleiotropic drug efflux pump across the cell membrane of tumor cells expressing the multidrug resistance phenotype, whereas the renal organic anion and organic cation secretory systems serve the function of pleiotropic drug transport across the proximal tubule epithelium. Because most known substrates for P-glycoprotein are organic cations, we tested the hypothesis that the physiological function of this protein in the kidney is to mediate renal organic cation secretion. In one approach, we compared the postnatal development of organic cation transport with that of kidney mdr gene expression. Cimetidine-sensitive uptake of classical substrates for renal secretion (N-methyl nicotinamide and tetraethylammonium) into kidney slices developed gradually in neonate mice, reaching adult capacity in 4 to 6 weeks. P-glycoprotein and its mRNA, as estimated by immunohistochemical methods and RNAse protection analysis, were undetectable at birth and were expressed abruptly at the adult level between 2 and 3 weeks of age. In another approach, classical inhibitors of renal organic cation secretion (cimetidine and cyanine 863) failed to reverse resistance to adriamycin in Chinese hamster ovary and P388 cell lines, which possess the phenotypic traits of multidrug resistance. These results suggest that the cimetidine-sensitive component of organic cation secretion is mediated by a protein other than the P-glycoprotein in the mammalian kidney.

Anglo- and Mexican-American preschoolers at home and at recess: activity patterns and environmental influences

Habitual physical activity in children is related to physical fitness and appears to mediate cardiovascular disease (CVD) risk factors. We studied the physical activity patterns and associated variables of a large bi-ethnic cohort of 4-year-old children from low to middle socioeconomic families. Trained observers coded the behavior of 351 children (150 Anglo-American, 201 Mexican-American; 182 boys, 169 girls) during two 60-minute home visits and two unstructured recesses lasting up to 30 minutes each at 63 different preschools. Findings indicated that although children were much less active at home, there were low but significant correlations between their activity patterns at home and during recess (r = .13). Children who had activity-promoting toys at home also tended to have them available during preschool recess (r = .20). Ethnic differences were evident for both activity and environmental variables. Mexican-American children were less active than Anglo children at home (p less than .002) and during recess (p less than .03), thus adding to the adult literature that has found Mexican-Americans to be less active than Anglos, and supporting to the notion that physical activity life-style habits may be established in early childhood. In both settings, Mexican-American children spent more time in presence of adults (home, p less than .04; recess, p less than .03) and had access to fewer active toys (home, p less than .001; recess, p less than .05). Gender differences were also evident for both activity and environmental variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrinsic resistance to anticancer agents in the murine pancreatic adenocarcinoma PANC02

PANC02 is a ductal adenocarcinoma of the pancreas that is resistant to every known class of clinically active antitumor agent. To study the mechanism(s) underlying the intrinsic drug resistance of this tumor, a mammary adenocarcinoma (CA-755) that also grows in C57/BL mice and is known to be drug sensitive was used for comparison. PANC02 resistance and CA-755 sensitivity to several antitumor agents and to X-ray therapy was confirmed in mice, and PANC02 also demonstrated relative resistance in tissue culture. Relative to Chinese hamster ovary (CHO) and CA-755 cells, PANC02 did not appear to show a higher rate of mutation to drug resistance in culture as based on the 6-thioguanine resistance marker. Although P-glycoprotein characteristic of the multidrug resistance (MDR) phenomenon could be demonstrated at the mRNA level using a sensitive RNAse protection assay, the level of expression found was several orders of magnitude lower than that observed in phenotypic MDR cell lines. Furthermore, quinidine failed to increase the sensitivity of PANC02 cells to Adriamycin under conditions that clearly potentiated the toxicity of the drug to a CHO cell line exhibiting classic MDR traits. The heterogeneity in the distribution of drugs was inferred as being significantly greater in PANC02 versus CA-755 cells in vivo as based on measurements of within-animal, within-tumor variance in the distribution of the marker compounds inulin and antipyrine. Although it may not be the only mechanism involved, this greater intratumor heterogeneity in drug distribution could theoretically play a major role in the intrinsic drug resistance of PANC02 in vivo.

Cranial nerve involvement with Lyme borreliosis demonstrated by magnetic resonance imaging

We report a patient with cranial nerve and meningeal symptoms secondary to Lyme borreliosis. MRI using gadolinium contrast material demonstrated this inflammatory process. The patient did not have the parenchymal lesions described in previous reports of patients with CNS Lyme borreliosis.

In vivo phosphorus NMR spectroscopy of skin using a crossover surface coil

A modified crossover surface coil with minimal B1 field penetration was used for collection of skin phosphorus NMR spectra. Projection imaging experiments show that the coil-sensitive volume is uniform at the phosphorus frequency, but strikingly nonuniform at the proton frequency. Experiments with an in vitro phosphorus phantom, designed to simulate skin and underlying tissue, demonstrated that 45.1% (+/- 1.2%) of total signal was derived from Sprague-Dawley rat skin and 19.3% (+/- 1.4%) of total signal was derived from Fischer-344 rat skin. 31P MR spectra of rat skin in vivo permitted resolution of four phosphorus compounds: nucleoside triphosphates, phosphocreatine (PCr), inorganic phosphate (Pi), and phosphomonoester. Spectra collected after skin flap surgery in Fischer-344 rats showed a 50.1% (+/- 7.6%) reduction in the ratio of PCr/Pi within 30 min of surgery, compared to presurgical PCr/Pi levels (P less than 0.01). Skin phosphorus spectra are potentially useful for assessment of skin flap and skin graft viability.

Mechanisms of resistance to 6-thioguanine in a murine pancreatic tumor

PANC02 is a unique experimental animal tumor that fails to respond significantly to any known clinically active antitumor agent. In this regard, the murine ductal adenocarcinoma resembles its human counterpart. To study the mechanism for its intrinsic resistance to 6-thioguanine (TG), we compared the metabolism of the drug in PANC02 and a reference, TG-sensitive adenocarcinoma, CA-755. In comparison with CA-755, PANC02 cells were approximately 6 times less sensitive to TG and CHO cells were 80 times less sensitive in tissue culture. Nevertheless, the incorporation of TG into the DNA of these three cell lines was approximately equal at the lowest concentrations capable of reducing cloning efficiency by 50%, i.e., 3.0-3.8 pmol (dthioGMP)/nmol (dGMP). In mice bearing bilateral implants of CA-755 and PANC02, only CA-755 responded to TG treatment. At various doses used on various schedules, the incorporation of TG into CA-755 DNA readily achieved that observed to be cytotoxic to the cells in vitro, whereas the incorporation into the DNA of PANC02 tumor cells did not. Although the biochemical basis for the poor incorporation of TG into the DNA of PANC02 in vivo is not known, this factor appears to explain the refractoriness of PANC02 as compared with CA-755 to this antitumor antimetabolite.

Porphyrins as contrast media

The interest in tissue distribution of variously labeled or otherwise detectable natural and synthetic porphyrins and porphyrin derivatives dates back well over 60 years. Although a considerable interest in fluorescent tumor localization and therapy dominates the history of porphyrin biodistribution studies, many investigators have evaluated the diagnostic and therapeutic characteristics of porphyrins with radioactive, radiopaque, and paramagnetic qualities. In this paper, a review of the use of porphyrins as nuclear medicine, X-ray, and NMR contrast agents is presented.

Human cytomegalovirus productively infects primary differentiated macrophages

Monocytes are one of the predominant cell types in the peripheral blood that are infected by human cytomegalovirus (HCMV). Although virus can be detected in these cells in vivo, HCMV replication in cultured monocytes has been unsuccessful. In this study, we demonstrate efficient HCMV replication in cultured monocytes. HCMV permissiveness in these cells was dependent on nonadherent cell-induced stimulation of the monocyte, with subsequent morphological differentiation into macrophages. Approximately 40% of the cells infected by virus were detected by immunofluorescent staining with both immediate-early and late antibodies. In addition, viral plaque assays demonstrated significant productive infection of macrophages. These observations are consistent with the suggestion that the monocyte/macrophage serves as a source of viral amplification and dissemination.

A discrete cis element in the human immunodeficiency virus long terminal repeat mediates synergistic trans activation by cytomegalovirus immediate-early proteins

The major immediate-early (IE) promoter of human cytomegalovirus directs the expression of several differentially spliced and polyadenylated mRNAs that encode isoformic proteins with apparent molecular masses of 55, 72, and 86 kDa. All of these proteins are potent transcriptional regulatory proteins. We are interested in the collateral interactions between human cytomegalovirus and human immunodeficiency virus (HIV) in the context of dual infection of a cell. The roles of the specific IE protein isoforms and their respective response elements involved in trans activation of the HIV long terminal repeat (LTR) are not known. Here we present evidence that major IE proteins IE86, IE72, and IE55 are capable of trans-activating the HIV LTR in a T-cell line, HUT-78. The IE55 isoform noncooperatively stimulates the HIV LTR in the presence of either isoform IE72 or IE86. Interactions between isoforms IE72 and IE86, however, result in strong synergistic activation of the LTR. Our results suggest that a specific 155-amino-acid protein domain that is unique for the IE86 protein participates in this synergic interaction. Point mutational analysis of the LTR identified a distinct cis-acting target site, located between nucleotide positions -174 and -163, that mediates exclusively synergistic trans activation by the IE72 and IE86 proteins. Finally, this study underscores the role of a cellular intermediate(s) for communicating the synergic interactions between two IE trans activators.

Intrathoracic airstream temperatures during acute expansions of thoracic blood volume

1. To determine the validity of employing intrathoracic heat flux as a reflection of changes in bronchial blood flow, we used a thermal probe to record airstream temperatures within the tracheobronchial tree in five normal and five asthmatic subjects during isocapnic hyperventilation challenges with and without inflation of the lower limb bladders of a pressure suit. 2. During hyperpnoea, airstream temperatures fell progressively in both subject groups. When blood volume was acutely shifted from the legs into the thorax via anti-shock trousers, airstream temperatures within the tracheobronchial tree rose and were significantly higher than the temperature recorded during hyperpnoea alone. In the normal subjects, once hyperpnoea ceased, the rate of airway re-warming was similar whether or not the anti-shock trousers were inflated. In the asthmatic subjects, however, shifting blood into the thorax attenuated the obstructive response to hyperpnoea and slowed the rate of re-warming. 3. These data demonstrate that changes in airway blood volume are reflected in fluctuations in intrathoracic heat exchange and that disruption of the end hyperpnoea thermal gradient attenuates the airway obstruction that follows hyperpnoea. Since the bronchial blood supply is the major source of heat to the airways, this circulation may play an important role in thermally induced asthma.

2'-Deoxy-6-thioguanosine 5'-triphosphate as a substrate for purified human DNA polymerases and calf thymus terminal deoxynucleotidyltransferase in vitro

2'-Deoxy-6-thioguanosine 5'-triphosphate (S6dGTP), a metabolite of the antileukemia agent 6-thioguanine, was evaluated as a substrate for purified human DNA polymerases. Using bacteriophage M13 single-strand DNA as a template, S6dGTP substituted efficiently for dGTP and stimulated DNA synthesis in reactions without dGTP, with DNA polymerases alpha, delta, and gamma from the human leukemia cell line K562. The apparent Km values for dGTP and S6dGTP were very similar, i.e., 1.2 microM each for polymerase alpha, 2.8 and 3.6 microM, respectively, for polymerase delta, and 0.8 microM each for polymerase gamma; however, the relative Vmax values for the modified nucleotide were 25-50% lower than those of the corresponding natural substrate. Using a highly sensitive electrophoretic assay of chain elongation across M13mp9 (+)-strand DNA by the aforementioned human DNA polymerases, S6dGTP was shown to be incorporated at the 3' end of the nascent growing DNA chain, and the patterns of chain extension with S6dGTP as substrate were identical to those obtained in the presence of dGTP. There were no major differences using S6dGTP in place of dGTP with these DNA polymerases; however, at higher concentrations (1-10 microM) the analog stimulated primer elongation in reactions without dATP, indicating some misincorporation at sites of S6G.T base pairs during DNA synthesis. Using p(dA)12-18 as the initiator for calf thymus terminal deoxynucleotidyltransferase, S6dGTP inhibited the incorporation of all four natural deoxyribonucleoside 5'-triphosphates into the primer, in a competitive manner. The apparent Ki values for the analog were 6-20 times lower than the Km values for the four endogenous substrates. As a substrate, S6dGTP was added to the 3'-hydroxyl termini of primer, although tailing efficiency with the analog was lower than that in the presence of the natural substrate. These findings indicate that S6dGTP is a relatively good substrate for several mammalian DNA polymerases, including terminal deoxynucleotidyltransferase.

Isolation and characterization of Borrelia burgdorferi from Illinois Ixodes dammini

Ixodes dammini ticks from two northwestern Illinois sites were found to be infected with Borrelia burgdorferi at rates of 19 and 32%. B. burgdorferi isolates, one from each site, had protein and antigenic patterns similar to those of the B-31 strain. An indirect immunofluorescence method proved to be more sensitive than dark-field microscopy in detection of these spirochetes. A modified BSK medium containing rifampin was found to be more efficient for spirochete isolation than unsupplemented BSK medium.

Blood pressure reactivity to exercise: stability, determinants, family aggregation, and prediction

Previous studies have shown blood pressure reactivity to exercise predicts future resting blood pressure. Subjects in this study were 206 healthy Mexican-American and Anglo-American families with fifth or sixth grade children. A total of 539 children (mean age = 12 years) and parents (mean age = 37 years) had complete data at baseline, and 79% were remeasured 48 months later. Blood pressure was measured during a submaximal cycle ergometer fitness test. Reactivity measures included systolic blood pressure at 70% of maximal heart rate (SBP70) and slope of the blood pressure-heart rate association during exercise (SLOPE). Stability of reactivity measures over 24 months varied from .22 to .63 (all p less than 0.001). Correlates of blood pressure reactivity in parents included resting heart rate, gender, age, and sodium intake. Correlates of reactivity in children included resting heart rate, body mass index, and age. Modest but significant levels of family aggregation of blood pressure reactivity were observed. In stepwise multiple regression analyses, SBP70 at baseline predicted resting blood pressure 48 months later in parents but not in children. The present results confirm previous studies indicating systolic blood pressure reactivity to exercise is a significant predictor of later resting blood pressure.

Enhancement of RNA polymerase II initiation complexes by a novel DNA control domain downstream from the cap site of the cytomegalovirus major immediate-early promoter

The major immediate-early promoter (MIEP) of human cytomegalovirus is a remarkably strong RNA polymerase II transcription control unit. We have identified and characterized a novel regulatory domain associated with MIEP downstream from the initiation site of transcription. The downstream regulatory region was first identified by analyzing a series of mutations in the 5' untranslated leader exon. This regulatory domain was shown to enhance the number of functional initiation complexes without significantly altering the apparent elongation rate by RNA polymerase II transcription. In addition, run-off in vitro transcription and DNA-binding experiments identified two distinct downstream elements that specify the interaction of cellular transcription factors. One of these elements contains a reiterated sequence motif, present twice within the leader exon. The second element is an 18-bp sequence located at approximately nucleotide position +33 that is conserved between strains of cytomegalovirus from different species. On the basis of two criteria, an oligonucleotide competition assay and oligomerization upstream of the promoter, the binding of factors to the conserved box was shown to be critical for mediating the level of transcription from MIEP. Two discrete cellular nuclear proteins, designated LTF A and B (for leader transcription factor A and B binding factors), were found to specifically recognize the conserved element. This study of promoter-proximal elements within transcribed sequences demonstrates the recognition of the control domain at the DNA level that functions to increase the number of committed RNA polymerase II transcription complexes.

Differentiation induction of human promyelocytic leukemia cells by 10-hydroxycamptothecin, a DNA topoisomerase I inhibitor

The cytotoxic and differentiating effects of 10-hydroxycamptothecin (HCPT) in the human promyelocytic leukemia cell line HL-60 were examined. By trypan blue dye exclusion, a 24-h exposure of the cells to 0.1 microM of the drug was found to be cytotoxic. Exposure of the cells to lower concentrations (0.001-0.01 microM) for 3 days reduced cell proliferation and induced cell differentiation. As determined by Wright-Giemsa staining, approximately 25% of promyelocytic cells became metamyelocytes, banded and segmented neutrophils. Electron microscopy demonstrated alterations in the ultrastructure of HCPT-induced HL-60 cells that included the formation of lobulated nuclei and the accumulation of large vesicles and small myelin bodies as well as glycogen-like particles in the cell periphery. Qualitatively similar results were obtained in a subline of HL-60 that is resistant to 4'-(9-acridinylamino)methanesulfon-m-anisidide (m-AMSA); however, the rate and extent of induced nitroblue tetrazolium-positive cells by HCPT and several other agents were greater in the resistant cell line. Under conditions that induced cell differentiation, HCPT sharply inhibited [3H]thymidine incorporation into DNA and increased the rate of protein synthesis without an effect on the rate of RNA synthesis. The measurement of DNA topoisomerase I activity in nuclear extracts from both HCPT- and DMSO-treated cells demonstrated that the enzyme was decreased in mature cells compared to nondifferentiated controls. The data suggest that progressive reduction of DNA topoisomerase I activity may be associated with cell differentiation, but whether HCPT-induced differentiation is mediated by inhibition of the enzyme is inconclusive.

Pathogenesis of HIV encephalitis

A wide spectrum of infectious agents attack the central nervous system (CNS) of acquired immunodeficiency syndrome (AIDS) patients. Human immunodeficiency virus (HIV) itself, infects the CNS of a subgroup of these patients. The mechanism behind why HIV enters the CNS is unclear. We have observed an interesting association between HIV and opportunistic viral infections that may explain why HIV enters the brain. Infection of the CNS by opportunistic agents results in recruitment of latently HIV-infected monocytes. Upon differentiation into macrophages these cells produce abundant HIV. Latent HIV-infection of monocytes/macrophages provides a unique opportunity for cooperativity between opportunistic infections and HIV in mediating CNS damage.

Survey for Ixodes spp. and Borrelia burgdorferi in southeastern Wisconsin and northeastern Illinois

Forested areas adjacent to Milwaukee, Wis., and Chicago, Ill., were investigated for rodents and ticks infected with Borrelia burgdorferi, the causative agent of Lyme disease. White-footed mice (Peromyscus leucopus or Peromyscus maniculatus), meadow voles (Microtus pennsylvanicus), and eastern chipmunks (Tamias striatus) were captured; and specimens from these animals were cultured for B. burgdorferi to define whether the midwestern Lyme disease area currently encompasses these large metropolitan centers. During 1988, B. burgdorferi was successfully cultured from the tissues of two M. pennyslvanicus voles captured from the Chicago area. However, no Ixodes spp. ticks were captured. None of 274 animals captured from sites I3 and 12 additional sites in Wisconsin and Illinois during the summer of 1989 were infected with B. burgdorferi or Ixodes spp. In addition, no ticks were recovered when the underbrush in 11 contiguous areas was flagged. Apparently, B. burgdorferi is rarely found in these areas because of the absence of the appropriate tick vectors. Further studies are needed to monitor the dispersal of B. burgdorferi-infected Ixodes dammini into this heavily populated midwestern region.

Improved method for in vivo magnetic resonance contrast media research

This paper describes an approach for contrast media research with which high resolution MR images of rats can be studied before, during, and after intravenous contrast media administration. Using a probe designed to hold up to eight rats, the contrast-enhancing properties in normal rat brains of Gd-DTPA, a low molecular weight compound, and polylysine-(Gd-DTPA), a high molecular weight compound, were compared simultaneously in two groups of four rats each. Signal intensity-time graphs, as measured over various anatomical structures of the normal rat head, demonstrated the feasibility of directly comparing enhancement patterns of two pharmacologically different contrast agents and obtaining relevant data in a single experiment.