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.

BEACHES: an observational system for assessing children's eating and physical activity behaviors and associated events

An integrated system for coding direct observations of children's dietary and physical activity behaviors was developed. Associated environmental events were also coded, including physical location, antecedents, and consequences. To assess the instrument's reliability and validity, 42 children, aged 4 to 8 years, were observed for 8 consecutive weeks at home and at school. Results indicated that four 60-min observations at home produced relatively stable estimates for most of the 10 dimensions. Interobserver reliabilities during live and videotaped observations were high, with the exception of "consequences" categories that occurred in less than 1% of observed intervals. Evidence of validity was provided by findings that antecedents were associated with respective dietary and physical activity behaviors. The five physical activity categories were validated by heartrate monitoring in a second study. The Behaviors of Eating and Activity for Children's Health Evaluation System is appropriate for studying influences on diet and physical activity in children in a variety of settings.

Fetal alcohol syndrome: review of the literature and case report

Fetal Alcohol Syndrome (FAS) is now recognized as a reality for the unborn if the pregnant woman ingests alcohol during the gestation period. Significant oro-facial problems occur as well as mental and behavior problems. This article reviews the current thought on oro-facial and dental diagnosis and therapy.

Oxygenation of desmosterol and cholesterol in cell cultures

In order to determine whether hydration of the delta 24 bond of desmosterol contributes to the formation of the regulatory oxysterol, 25-hydroxycholesterol, [3H]desmosterol was incubated with two cultured cell lines and the labeled products were analyzed. Small amounts of 25-hydroxycholesterol were formed with Chinese hamster lung (Dede) cell cultures, but not with mouse fibroblast (L) cell cultures. Apparently, desmosterol was converted into cholesterol, a process that does not occur in L cells, before 25-hydroxycholesterol takes place. No reliable evidence could be obtained for hydration of the delta 24 bond or for the reverse reaction upon incubation of [3H]25-hydroxycholesterol. Oxygenation of desmosterol occurred in both Dede and L cell cultures to give a mixture of 24(R)- and 24(S)-25-epoxy-cholesterol. This reaction, along with the production of 7-oxygenated sterols, may account for low levels of HMG-CoA reductase repressor activity previously found to be associated with delta 24 sterols.

Characterization of macrophage subsets regulating murine natural killer cell activity

We examined the relationship of I-A expression by normal murine macrophages to their immunoregulatory role on natural killer cell activity. Macrophages were isolated on the basis of plastic adherence; characterized on the basis of conventional markers such as phagocytic ability, cytoplasmic non-specific esterase activity, surface MAC-1 and F4/80 antigen expression; and then used for functional studies relative to their expression of surface I-A. Two functional macrophage subsets were identified: NK-stimulatory and NK-suppressive subsets. The former function was associated with splenic macrophages, which were predominantly I-A+ as identified with a radioautographic immunolabeling technique; the latter function with peritoneal macrophages which were predominantly I-A-. Loss of macrophage I-A expression in vitro was delayed in the presence of indomethacin and enhanced in the presence of PGE2, indicating that PGE2 down-regulates I-A expression on macrophages. The NK stimulatory function of I-A+ macrophages was attributable to a soluble mediator, identified as IFN-gamma, since the stimulatory ability was abrogated with an anti-IFN-gamma antibody. I-A expression appears to be important for the stimulatory function, since some interference with this function was noted in the presence of anti-I-A antibody. The NK-suppressor function of I-A- macrophages was attributable to the soluble mediator PGE2, since this function was abrogated with indomethacin or anti-PGE2 antibody. These results are relevant to the understanding of normal in vivo immunoregulation by macrophages.

Down-regulation of macrophage I-A expression in tumor-bearing mice

During the subcutaneous growth of a highly metastatic mammary adenocarcinoma line, C3-L4 in C3H/HeJ mice, there was a rapid decline in macrophage I-A expression in vivo. The incidence of I-A+ macrophage subset in the spleen declined from 90% to 10% or less within 5 days of tumor transplantation, with a parallel decline in their absolute number. I-A expression in these cells remained suppressed for a long time until tumors became necrotic and ulcerated. In spite of a low incidence (15-20%) of I-A+ macrophages in the normal peritoneal space, tumor transplantation caused a long-lasting decline in their incidence to one-fourth of the original level. Tumor-associated macrophages were predominantly I-A- throughout the tumor life span. Thus I-A- macrophages dominated in all anatomical compartments in tumor-bearing mice. Macrophage I-A expression was substantially restored (spleen) or stimulated (peritoneal space and tumor) in tumor-transplanted mice subjected to chronic indomethacin therapy in the drinking water, indicating a reversal of prostaglandin-mediated down-regulation of macrophage I-A expression in situ. Concomitantly, this therapy caused regression of the primary tumors and prevented lung metastasis. These results are relevant to the understanding of tumor-host interactions and its exploitation for immunotherapy.

Role of natural killer cells in the modulation of primary antibody production by purine nucleosides and their analogs

Previous results from this laboratory demonstrated that treatment of mice with the adenosine analog tubercidin (Tub) reduced natural killer (NK) cell activity while stimulating antibody production whereas the deoxyadenosine analog, 2-fluoroadenine arabinoside-5'-monophosphate (FaraAMP), produced opposite effects; i.e., it stimulated NK cell activity at doses that inhibited antibody formation (Cancer Res. 48, 4799, 1988). Since NK cells have been reported to play a suppressor role in immunoglobulin induction, it was hypothesized that the actions of Tub and FaraAMP on antibody production occurred secondary to their opposing effects on NK cells. To test this hypothesis, abilities of these nucleoside analogs to modulate primary antibody response to sheep red blood cells were evaluated in a C57BL/6 mutant mouse lacking NK cell activity (the beige mutation. C57BL/6-bg/bg). As previously found with C3H/He mice. NK cell activity was inhibited (Tub, doses 2-6 mg/kg/day for 3 days) or stimulated (FaraAMP, doses 75-250 mg/kg/day for 3 days) in heterozygous mice C57BL/6-bg/+. In support of the hypothesis, these nucleosides had no effect on primary antibody formation in the homozygous mutant mice at doses that clearly stimulated (Tub) or inhibited (FaraAMP) this immune response in heterozygous C57BL/6-bg/+ animals. This results was corroborated in C57BL/6 wild-type mice by abrogation of NK cell activity using a monoclonal antibody to the NK cell surface glycophisingolipid, ganglio-n-tetraosylceramide. We conclude that under the conditions of drug administration, modulation of primary antibody formation by Tub and FaraAMP in mice occurs indirectly via NK cells. Similar experiments using the potent ADA inhibitor, deoxycoformycin, indicated that its enhancement of primary antibody formation is independent of NK cell activity.

The Caltrac accelerometer as a physical activity monitor for school-age children

The performance of the Caltrac accelerometer was studied in elementary school-age children under field and laboratory conditions. In Study 1, 35 children (20 boys, 15 girls, mean age = 10.8 yr) wore the accelerometer and a heart rate (HR) monitor for 2 d. Caltrac activity counts per hour were compared to the mean "activity HR", which was calculated by subtracting the mean of the five lowest HRs of the day from each recorded HR. Pearson r's between accelerometer and activity HR were 0.54 (P less than 0.001) on day 1 and 0.42 (P less than 0.02) on day 2. Inter-instrument reliability in the field was r = 0.96. Both accelerometer and HR data were significantly correlated with physical activity recalls of the same day. In Study 2, 15 children walked/ran for 10 min at 3, 4, and 5 mph on a horizontal treadmill while wearing two accelerometers. Oxygen uptake was directly measured each minute. Reliability of the Caltracs in the laboratory was 0.89. Activity count correlated r = 0.82 (SEE = 23%) with net calorie cost per kg of body weight. Net caloric expenditure per kg of weight was 0.101 kcal.kg-1.d-1 per Caltrac activity count. These data support the use of the Caltrac accelerometer as a physical activity measure for school-age children, and the objective data tended to corroborate the children's short-term activity recalls.

Characterization of the DNA damage in 6-thioguanine-treated cells

6-Thioguanine (TG) incorporation into DNA has been associated with cytotoxicity and DNA damage in Chinese hamster ovary (CHO) and murine leukemia L1210 cells. According to alkaline elution analysis, single-strand breaks (SSB) occur in both cell types. DNA-protein and interstrand crosslinks are prominent features of TG effects in L1210, CEM, and HL-60 but not CHO cells. To assess which DNA strand experiences SSB in CHO cells, the cells were synchronized by growth to confluence (late G1, S). The cells were then diluted into fresh medium so that they underwent a round of division during a subsequent 16-hr interval. They were treated with TG during this first cell cycle, and mitotic cells were harvested at the end of the first cycle using colcemid. SSB were determined in parental DNA (radiolabeled with thymidine during growth to confluence), TG-containing DNA (radiolabeled with [14C]TG during drug exposure), and daughter DNA (labeled with thymidine during the second cell cycle). SSB occurred in TG-containing DNA late in the second cell cycle after drug exposure and in the DNA synthesized from a TG-DNA template (daughter DNA). This observation is consistent with the known delayed cytotoxicity and chromosomal aberrations seen in CHO cells. The SSB suggest relatively normal elongation of DNA containing TG but altered synthesis and/or ligation from a TG-DNA template. This premise was tested in synchronized CHO cells. The DNA strand incorporating TG elongated naturally; however, DNA elongation was impaired in the cell cycle following TG treatment. The results are consistent with SSB in daughter DNA synthesized from a TG-DNA template due to inability to elongate the newly-synthesized strand.

Purine nucleoside modulation of functions of human lymphocytes

The accumulation of endogenous substrates in patients with adenosine deaminase deficiency or purine nucleoside phosphorylase deficiency is believed to be responsible for the immunodeficiency observed in these patients. To identify the lymphocyte populations that are most susceptible to these substrates, we investigated the effect of their nucleoside analogs on a number of T and B cell functions of human lymphocytes. We found that tubercidin (Tub), 2-chloro 2'deoxyadenosine (2CldA), 2-fluoro adenine arabinoside-5'phosphate (FaraAMP), and 9-beta-D-arabinosyl guanine (AraGua) inhibited the proliferative responses of human peripheral blood mononuclear cells (PBMC) to polyclonal activators (PHA, OKT3 mab) or to allogeneic PBMC in mixed lymphocyte cultures (MLC). Addition of recombinant IL-2 from the beginning of the culture did not alter the inhibition by Tub of the proliferative responses of PBMC. These purine nucleoside analogs also inhibited the proliferative responses of purified human peripheral blood CD4+ and CD8+ T cells to PHA and of purified B cells to SAC. The concentrations of these nucleosides required to achieve a given degree of inhibition of proliferative responses of T lymphocyte subpopulations or B cells was similar, suggesting that these analogs do not exhibit any selectivity for these purified lymphocyte populations. Tub and FaraAMP, respectively, inhibited and enhanced, at the effector phase, both NK cytotoxicity and specific T cell-mediated cytotoxicity. In contrast to these findings, LAK cytotoxicity at the effector phase was not significantly inhibited by Tub, and was not enhanced by FaraAMP. Both analogs inhibited rIL-2-induced proliferative responses of PBMC, but did not affect the generation of LAK cytotoxicity (induction phase) against the K562 targets when added at the beginning of the culture. This suggests that DNA synthesis is not required for LAK cell induction. Both Tub and FaraAMP inhibited immunoglobulin production (IgG and IgM) by PBMC in the PWM-induced system. These results demonstrate that purine nucleoside analogs significantly inhibited a number of functions of human lymphocytes. Although selectivity for T lymphocyte subpopulations and B cells was not observed, a differential effect of Tub and FaraAMP on LAK cytotoxicity versus NK cytotoxicity and specific T cell cytotoxicity was found.

Adenosine receptors and modulation of natural killer cell activity by purine nucleosides

Natural killer (NK) cell activity is inhibited by the adenosine analogue tubercidin (Tub) and stimulated by the deoxyadenosine analogue 2-fluoro-1-beta-D-arabinofuranosyladenine 5'-monophosphate (F-ara-AMP) in the spleen lymphocytes from mice treated with the drugs in vivo (T. Priebe et al., Cancer Res., 48:4799, 1988). The present report demonstrates that the inhibition by Tub and stimulation by F-ara-AMP of NK cell activity are readily demonstrable in murine and human lymphocytes exposed to the drugs in vitro. In mouse spleen lymphocytes, NK cell activity is also inhibited by adenosine receptor A2 agonists, whereas potent A1 receptor agonists are more effective stimulators. Inhibition produced by adenosine, deoxyadenosine, and adenosine receptor agonists, but not by Tub, is partially prevented by the adenosine receptor antagonist 1,3-dipropyl-8-phenylxanthine amine congener. Agents that stimulate NK cell activity (deoxyadenosine, A1 receptor agonists, F-ara-AMP) do not increase further the 1.5-fold enhancement produced by a 10(-6) M concentration of 1,3-dipropyl-8-phenylxanthine amine congener. The nucleoside transport inhibitor, p-nitrobenzylthioinosine 5'-monophosphate, has no effect on NK cell activity or intracellular ribonucleotide pools; however, it partially prevents Tub 5'-triphosphate formation, ATP depletion, and NK cell inhibition in mouse spleen cells treated with Tub. p-Nitrobenzylthioinosine 5'-monophosphate also partially prevents the F-ara-AMP stimulation of NK cell activity, but it does not influence the effects of adenosine or deoxyadenosine. The results obtained with the adenosine receptor agonists suggest roles for both A1 and A2 receptors in regulating murine NK cell activity. Tub inhibition of NK cell activity does not appear to involve adenosine receptors; however, inhibition by the other agents may be mediated via an A2 receptor (stimulatory for adenylyl cyclase). Since p-nitrobenzylthioinosine 5'-monophosphate inhibited the stimulation of NK cell activity by F-ara-AMP, this stimulation may occur via an intracellular "P" site (inhibitory to adenylyl cyclase).

T-cell-induced expression of human immunodeficiency virus in macrophages

Macrophages are major reservoirs of human immunodeficiency virus (HIV) in the tissues of infected humans. As monocytes in the peripheral blood do not show high levels of infection, we have investigated the expression of HIV in T-cell-activated, differentiated macrophages. Peripheral blood mononuclear cells were isolated from HIV-seropositive individuals and stimulated with antigens or mitogens, and the nonadherent fraction was removed. Macrophages were cultured alone for 2 weeks, and HIV expression was assessed. Results from p24 antigen capture assays demonstrated that the presence of autologous T cells and concanavalin A or autologous T cells and allogeneic cells for the initial 24 h of culture induced HIV expression in 35 of 47 (74%) HIV-seropositive patients tested. The macrophage monolayers could be immunostained with anti-HIV antibodies to reveal discrete infectious centers, indicating that complete virus replication was occurring in the macrophages and that infection of adjacent cells was mediated by cell-cell contact. Time course studies of the interval of coculture of the adherent and nonadherent cells indicated that 24 h (but not 2 h) was sufficient for induction of HIV in the macrophages. Direct contact between the adherent cells and activated T cells was required as well. Since the presence of autologous T cells also appeared to be necessary, induction of HIV expression in macrophages may be genetically restricted. HIV-seronegative nonadherent cells were able to induce HIV expression in macrophages from HIV-seropositive donors, demonstrating that the virus originated in the monocytes and was reactivated in the context of a classic T-cell-mediated immune reaction. The high percentage of monocytes from HIV-seropositive donors which can be induced to replicate HIV by activated T cells suggests that infection of monocytes may be critical to the pathogenesis of this lentivirus infection.

Cultured human brain capillary endothelial cells are permissive for infection by human cytomegalovirus

Human cytomegalovirus (HCMV) infection is associated with a variety of systemic and neurologic diseases. In vitro HCMV growth is usually studied in fibroblasts, while in vivo HCMV growth is frequently observed in a wide variety of cell types including glia, neurons, and human brain capillary endothelial (HBCE) cells. To examine the biology of HCMV in HBCE cells, we have established a procedure for isolating these cells from human brain temporal lobectomies. Greater than 99.0% of these cultured cells were identified as HBCE cells on the basis of positive staining for factor VIII-related antigen-Von Willebrand's factor (F VIII) and Ulex Europaeus agglutinin I (UEA I). HCMV antigens were detected by immunocytochemistry in HBCE cells after infection with strain AD 169. Intracellular virions were observed in infected cells by electron microscopy and infectious virus was released from HBCE cells. In addition, infected cells were confirmed as endothelial cells by double staining with antibodies to F VIII and HCMV.

Is herpes simplex virus associated with peptic ulcer disease?

To test the hypothesis that herpes simplex virus type 1 (HSV-1) may be associated with peptic ulcer disease, we examined ulcerative lesions of the distal stomach and proximal duodenum for the presence of nucleic acids and antibodies specific for HSV-1. Utilizing in situ hybridization, immunocytochemistry, and polymerase chain reaction with sequencing, gastric or duodenal tissues from 4 of 22 patients (18%) with documented peptic ulcer disease demonstrated the presence of both specific HSV-1 nucleic acid sequences and proteins. HSV-1 was found restricted in clusters of cells near the margin of the ulcer but was absent at sites distal to the lesion. Several of such HSV-1-infected cells also contained cholecystokinin. These cholecystokinin-containing cells are of neuroendocrine origin and receive contact from the vagal nerve. Campylobacter pylori bacteria were not found in three of the four peptic ulcer tissues that harbored HSV-1. Further, none of the stomach or duodenal tissue samples from 33 patients undergoing clinical evaluation, but having no evidence of peptic ulcer disease, had HSV-1 materials. Thus, our data suggest that a subset of peptic ulcer disease may be associated with HSV-1 and raise the possibility that some peptic ulcers may be caused by this virus.