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Biomedical subjects

J G Tilles

Publications and source records attributed to J G Tilles.

At least 19 recordsLinked to original sources
PubMed2000

Sex-associated differences in the antibody-dependent cellular cytotoxicity antibody response to measles vaccines.

In some countries, excessive non-measles-related mortality has been observed among female recipients of high-titer measles vaccines. We determined if differences in the immune response to measles vaccines underlie the excessive female mortality by measuring the measles virus (MV)-specific antibody-dependent cellular cytotoxicity (ADCC) antibody response in 65 3-year-old Gambian children immunized with Edmonston-Zagreb medium-titer (EZ) or Schwarz standard vaccines during infancy. Among the 20 females and 22 males with undetectable anti-MV antibodies at the time of immunization, females had significantly lower ADCC than males (median cytotoxicities of 1/100 serum dilutions = 8.4 and 12%, respectively; P = 0.04). This sex-associated difference was present only among the six female and seven male recipients of EZ vaccine (median cytotoxicities = 5.1 and 19.0%, respectively; P = 0.02). There were no significant sex-associated differences in neutralizing antibody activity. Decreased ADCC antibody activity may contribute to the lower survival rate observed in females receiving high-titer measles vaccination.

Antibody-Dependent Cell Cytotoxicity↗
PubMed1999

Antibody-dependent cellular cytotoxicity independently predicts survival in severely immunocompromised human immunodeficiency virus-infected patients.

The exact immune defects leading to human immunodeficiency virus (HIV)-associated opportunistic infections, malignancies, and death are unknown. In this study, the relationship between survival and 2 immune functions, cytomegalovirus-specific antibody-dependent cellular cytotoxicity (ADCC) and natural killer (NK) activity, was determined by using peripheral blood mononuclear cells from 39 severely immunocompromised patients (median CD4 count, 7). Median follow-up was 414 days; 15 subjects died and 24 remained alive. In a Kaplan-Meier analysis, high baseline ADCC (>median) was associated with improved survival (P=.05). A similar trend was observed for NK activity (P=.1). In a multivariate model controlling for baseline CD4 cell count, HIV RNA, and use of protease inhibitors during follow-up, high ADCC, but not high NK activity, remained significantly associated with a lower risk of death (relative risk, 0.18; 95% confidence interval, 0.05-0.75). ADCC may be an important determinant of disease progression independently of anti-retroviral therapy, CD4 cell count, and HIV RNA.

AIDS-Related Opportunistic Infections↗
PubMed1999

Successful short-term suppression of clarithromycin-resistant Mycobacterium avium complex bacteremia in AIDS. California Collaborative Treatment Group.

During a randomized study of clarithromycin plus clofazimine with or without ethambutol in patients with AIDS and Mycobacterium avium complex (MAC) bacteremia, eight participants received additional antimycobacterial drugs following the detection of a clarithromycin-resistant isolate (MIC, > 8 micrograms/mL). A macrolide (seven received clarithromycin, one azithromycin) and clofazimine were continued; additional treatment included various combinations of ethambutol, ciprofloxacin, amikacin, and rifabutin. After the detection of a resistant isolate and before receipt of additional antimycobacterials, the median peak MAC colony count in blood was 105 cfu/mL (range, 8-81,500 cfu/mL). After additional antimycobacterials, the median nadir MAC colony count was 5 cfu/mL (range, 0-110 cfu/mL). Five (63%) of eight patients had a > or = 1 log10 decrease, including two who achieved negative blood cultures; all of these responses occurred in patients originally assigned to clarithromycin plus clofazimine. Treatment of clarithromycin-resistant MAC bacteremia that emerges during clarithromycin-based treatment can decrease levels of bacteremia and transiently sterilize blood cultures.

AIDS-Related Opportunistic Infections↗
PubMed1998

The pathogenesis of viral-induced diabetes.

Serologic case-control studies have suggested an association between coxsasckie group B viruses and insulin-dependent diabetes mellitus (IDDM). New investigations have identified enteroviral nucleic acid in the peripheral blood mononuclear cells of newly-diagnosed patients with IDDM. The disease pathogenesis is dependent on several factors. including the genetics of the host, strain of virus, activation status of autoreactive T-cells, upregulation of pancreatic MHC-1 antigens, molecular mimicry between viral and beta cell epitopes and direct islet cell destruction by viral cytolysis. Epitopes (IDDM-E1 and E2) on glutamate decarboxylase 65 (GAD65) are the most common targets for antibody and cellular-mediated autoimmune beta cell destruction.

Animals↗
PubMed1997

In vitro effects of echinacea and ginseng on natural killer and antibody-dependent cell cytotoxicity in healthy subjects and chronic fatigue syndrome or acquired immunodeficiency syndrome patients.

Extracts of Echinacea purpurea and Panax ginseng were evaluated for their capacity to stimulate cellular immune function by peripheral blood mononuclear cells (PBMC) from normal individuals and patients with either the chronic fatigue syndrome or the acquired immunodeficiency syndrome. PBMC isolated on a Ficoll-hypaque density gradient were tested in the presence or absence of varying concentrations of each extract for natural killer (NK) cell activity versus K562 cells and antibody-dependent cellular cytotoxicity (ADCC) against human herpesvirus 6 infected H9 cells. Both echinacea and ginseng, at concentrations > or = 0.1 or 10 micrograms/kg, respectively, significantly enhanced NK-function of all groups. Similarly, the addition of either herb significantly increased ADCC of PBMC from all subject groups. Thus, extracts of Echinacea purpurea and Panax ginseng enhance cellular immune function of PBMC both from normal individuals and patients with depressed cellular immunity.

Acquired Immunodeficiency Syndrome↗
PubMed1997

The role of natural killer cells in viral infections.

Natural killer (NK) cells are important effectors for the lysis of both neoplastic and virus-infected cells. Lectin-like receptors on human NK cells, such as NKR-PIA and CD94, bind to target cell carbohydrate ligands and initiate the lytic process. In addition, P58 and P70 bind to major histocompatibility class I antigens on targets and mediate negative signals. Models using NK cell-deficient mice have proven useful in elaborating the role of NK cells in the immune defence against multiple viral agents. In addition, studies in humans have suggested a vital role of NK cells in the host defence against human immunodeficiency virus, herpesviruses, hepatitis B and C and other viruses. Several genetic disorders, chronic illnesses and infections have been associated with decreased NK function.

Animals↗
PubMed1997

A randomized evaluation of ethambutol for prevention of relapse and drug resistance during treatment of Mycobacterium avium complex bacteremia with clarithromycin-based combination therapy. California Collaborative Treatment Group.

Patients with AIDS and Mycobacterium avium complex (MAC) bacteremia are at high risk for relapse and emergence of resistant isolates during monotherapy with clarithromycin. Ninety-five AIDS patients with MAC bacteremia received clarithromycin plus clofazimine, with or without ethambutol, in a prospective, multicenter, randomized open-label trial. Of 80 patients with positive baseline cultures, sterilization or a 2 log10 reduction in colony-forming units of MAC in two consecutive blood cultures occurred in 69% of both groups. There were nine relapses in the two-drug arm and three in the three-drug arm. Kaplan-Meier estimates of risk of relapse at 36 weeks were 68% and 12%, respectively (P = .004). All relapse isolates were resistant to clarithromycin. Median time to clarithromycin resistance was 16 weeks with two drugs and 40 weeks with three drugs (P = .004). Ethambutol reduced relapses and emergence of clarithromycin resistance and should be considered an essential component of clarithromycin-based therapies for MAC bacteremia.

Adult↗
PubMed1997

Occurrence of coxsackievirus hepatitis in baby rabbits and protection by a formalin-inactivated polyvalent vaccine.

It was observed that 23-day-old New Zealand white rabbits came down with acute hepatitis demonstrable 3 days after intraperitoneal injection with 12 coxsackievirus group B strains. The model was used to evaluate a polyvalent, formalin-inactivated virus vaccine prepared with prototype strains of coxsackievirus groups B1-6. Seven-day-old animals received one intraperitoneal and two subcutaneous injections containing the vaccine or placebo. The regimen was repeated at 15 days of age. At 23 days of age, groups of rabbits were challenged with 1 x 10(5) plaque-forming units of a clinical strain of group B coxsackievirus and sacrificed 3 days later. The mean neutralizing antibody titer for the 12 strains tested (log2) was 4.5 +/- 1.0 eight days after the second dose of vaccine. In vaccinated animals, elevated liver function tests in the serum, and titer of virus and histopathologic abnormalities in the liver were significantly reduced for each strain tested compared with infected, unvaccinated controls. Cultures of the heart, skeletal muscle, pancreas, blood, and spleen were all negative. Thus, clinical strains of coxsackie group B viruses produced isolated hepatitis in baby rabbits. Prophylaxis with a polyvalent, inactivated-virus vaccine significantly reduced the severity of liver involvement for all 12 clinical strains tested.

Acute Disease↗
PubMed1995

The tolerance for zidovudine plus thrice weekly or daily trimethoprim-sulfamethoxazole with and without leucovorin for primary prophylaxis in advanced HIV disease. California Collaborative Treatment Group.

PURPOSE: Trimethoprim-sulfamethoxazole (TMP/SMX) is the preferred agent for prophylaxis of Pneumocystis carinii pneumonia (PCP) in patients with HIV infection, but frequent adverse events limit its usefulness. Intermittent dosing and supplementation with leucovorin have been tried in attempts to improve tolerance. We evaluated these strategies in persons with advanced HIV disease. METHOD: One hundred seven patients were enrolled. All had HIV infection, < 200 CD4+ lymphocytes per mm3, and no history of PCP. Fifty-two were randomized to TMP/SMX twice daily (BID); of these, 26 were randomized to leucovorin with each dose. Fifty-five patients were randomized to TMP/SMX (BID) 3 times per week; of these, 27 were randomized to leucovorin with each dose. All patients took zidovudine concurrently. RESULTS: The 24-week risk of discontinuation due to protocol-defined limiting toxicity was 24% with thrice-weekly TMP/SMX versus 42% with daily TMP/SMX (risk ratio 0.4; 95% CI 0.2 to 1.0). The risks of discontinuation for any reason were 41% and 59% (risk ratio 0.4; 95% CI 0.2 to 0.8). Clinical toxicity, such as headache and gastrointestinal distress, accounted for the observed difference in tolerance between dosing regimens. The 24-week risk of discontinuation due to protocol-defined toxicity was 33% in both the leucovorin and non-leucovorin groups (risk ratio 1.1; 95% CI 0.5 to 2.5). The risks of discontinuation for any reason were 53% and 47% (risk ratio 0.8; 95% CI 0.3 to 1.7). CONCLUSION: Intermittent therapy with TMP/SMX BID thrice weekly is better tolerated than daily BID therapy. Leucovorin use does not improve tolerance for chronic TMP/SMX dosing in AIDS, even among patients taking tablets daily.

AIDS-Related Opportunistic Infections↗
PubMed1995

Pathogenesis of virus-induced diabetes in mice.

Male CD-1 mice were challenged with a diabetogenic strain (E2) of coxsackievirus B4 (CVB4). At 7 weeks, 6 months, and 1 year after inoculation, mean histopathologic scores, postprandial blood glucose levels, and serum levels of antibody to islet cells were significantly elevated and mean fasting serum insulin levels significantly reduced in infected mice versus uninfected controls (P < .001 for each). At 7 weeks after infection, viral RNA, but not protein or infectious virus, was demonstrated in the pancreases of most infected mice. The pancreases of 4 of 12 and 0 of 10 infected animals were positive for viral RNA at 6 months and at 1 year after infection, respectively. Interferon-gamma-stimulated peritoneal macrophages were cytotoxic to islet cells with and without sera with high titers of islet cell autoantibody (ICA). Thus, islet cell destruction in mice infected with CVB4 strain E2 is associated with chronic islet cell inflammation, elevation of islet cell antibody, and prolonged presence of viral RNA in the pancreas. Stimulated peritoneal macrophages lyse islet cells directly and by an antibody-dependent mechanism.

Animals↗
PubMed1995

Age, sex, and household exposure are associated with the acute measles-specific antibody-dependent cellular cytotoxicity antibody response.

To determine whether functional antibody responses correlate with factors associated with severe measles, measles-specific antibody-dependent cellular cytotoxicity (ADCC) and neutralizing antibodies were measured in 114 Filipino children with measles. Children > 24 months old were more likely to have ADCC antibody in acute sera than were those < or = 24 months (odds ratio = 3.6, 95% confidence interval = 1.7-7.8). This age-related difference in ADCC prevalence was most apparent between younger and older girls. Among children < or = 24 months, a higher prevalence of ADCC antibody was associated with male sex, absence of lymphopenia, and household exposure to measles. The presence of ADCC antibody was not associated with malnutrition or diarrhea. Neutralizing antibody titers were lower in children with lymphopenia but showed no relationship with the other variables. Thus, the ADCC antibody response is associated with some risk factors related to measles severity. Attenuation of this response may contribute to the severity of infection.

Acute Disease↗
PubMed1994

Fluconazole combined with flucytosine for treatment of cryptococcal meningitis in patients with AIDS.

Treatment of cryptococcal meningitis with amphotericin B or fluconazole is often unsuccessful; in only 35%-40% of cases do CSF cultures become negative by 10 weeks after initiation of such therapy. We conducted a prospective, open-label clinical trial involving persons with AIDS to determine whether the rate of clinical success would improve when fluconazole (400 mg daily) was combined with flucytosine (150 mg/kg daily). At the conclusion of 10 weeks of therapy, 75% (95% confidence interval, 58%-87%) of 32 subjects' CSF cultures were negative. The Kaplan-Meier estimate of clinical success at 10 weeks was 63% (95% confidence interval, 48%-82%). The median time to negativity of the CSF culture was 23 days. Toxic side effects that were sufficiently severe to lead to the withdrawal of flucytosine were observed in nine subjects (28%). In this pilot study of fluconazole combined with flucytosine, the rate of clinical success at 10 weeks was greater than that previously reported with regard to the use of fluconazole alone or amphotericin B alone.

AIDS-Related Opportunistic Infections↗
PubMed1994

Measles virus-specific functional antibody responses and viremia during acute measles.

Antibody titers measured in functional and immunofluorescent assays were compared with proportions of peripheral blood mononuclear cells infected with measles virus in 8 adults with measles. In addition, a syncytium inhibition assay (SIA) for measuring neutralizing antibody using low-passage virus was compared with a standard plaque neutralization test (PNT). Antibody-dependent cellular cytotoxicity (ADCC) antibody rose later but attained higher titer than neutralizing, antibody-dependent complement-mediated lysis, IgM, or IgG antibodies. When titer changes between specimens from each patient obtained on different days were compared, only ADCC (r = .81, P = .026) and IgM (r = .81, P = .027) antibodies correlated with reductions in viremia. SIA and PNT correlated well (r = .93, P < .001). ADCC may be an important defense against measles. The delay in ADCC antibody relative to other antibodies is unique among viruses studied. The SIA is a useful alternative to the PNT for measuring measles neutralizing antibody.

Acute Disease↗
PubMed1994

The individual microbiologic effect of three antimycobacterial agents, clofazimine, ethambutol, and rifampin, on Mycobacterium avium complex bacteremia in patients with AIDS.

The individual antibacterial activities of clofazimine, ethambutol, and rifampin in the treatment of Mycobacterium avium complex bacteremia in patients with AIDS were determined. Sixty human immunodeficiency virus 1-infected patients who had at least one blood culture positive for M. avium complex were randomized to receive either clofazimine (200 mg), ethambutol (15 mg/kg), or rifampin (600 mg) once daily for 4 weeks. Only ethambutol resulted in a statistically significant reduction in the level of mycobacteremia. The median change in individual baseline colony counts was -0.60 log10 cfu/mL after 4 weeks of ethambutol (P = .046). In contrast, median changes in individual baseline colony counts were -0.2 log10 cfu/mL and +0.2 log10 cfu/mL for clofazimine and rifampin, respectively (both, P > .4). Ethambutol had greater antibacterial activity, as determined by changes in the level of mycobacteremia, than either rifampin or clofazimine, supporting its continued use in combination with other agents in the treatment of M. avium infection.

AIDS-Related Opportunistic Infections↗
PubMed1994

Efficacy of a polyvalent inactivated-virus vaccine in protecting mice from infection with clinical strains of group B coxsackieviruses.

A polyvalent vaccine developed from formalin-inactivated prototype strains of coxsackieviruses group B1-6 was tested for its ability to protect mice from acute infection with clinical strains. Adolescent male CD1 mice received an intraperitoneal injection, repeated once or twice at 8 day intervals, containing 0.3 ml placebo or vaccine. Eight days after the final dose of vaccine, groups of 4 mice were challenged with 1 x 10(4) plaque-forming units of a test strain of group B coxsackievirus, and killed 3 days later. The mean neutralizing antibody titers for the 29 strains tested (4 mice/strain, log2) were 2.2 +/- 0.6, 3.3 +/- 0.9 or 6.4 +/- 1.7 after 1, 2 or 3 doses of vaccine, respectively. In mice receiving 2 or 3 doses of vaccine, titers of virus were significantly lower in the pancreas and/or blood in 7/14 or 14/15 strains, respectively, compared to unvaccinated infected controls. Uninfected, vaccinated mice failed to develop islet cell autoantibodies, histopathological abnormalities in the pancreas, or evidence of viral RNA in the pancreas 12 weeks after 3 doses of vaccine. Thus, prophylaxis with a polyvalent, inactivated-virus vaccine reduced the severity of acute infection with clinical strains of coxsackie group B viruses. A schedule of 3 doses of vaccine was superior to 1 or 2 doses.

Acute Disease↗
PubMed1993

Comparison of measles virus-specific antibodies with antibody-dependent cellular cytotoxicity and neutralizing functions.

Measles virus-specific antibodies with antibody-dependent cellular cytotoxicity (ADCC) and neutralizing functions were compared in 25 healthy women. ADCC antibody was measured in a 12-h 51Cr release assay using peripheral blood mononuclear cells as effectors and Raji cells persistently infected with measles as targets. Neutralizing antibody was determined by the plaque neutralization test (PNT). ADCC and PNT titers correlated well (r = .80, P < .001). ADCC titers ranged from < 10 to > 10(6) and averaged 1.3 logs higher than PNT titers. Three sera with PNT titers of < 120, including 1 with a titer of < 8 (< 10(0.9)), had ADCC titers of > or = 10(2.5). Among subjects born in the United States, ADCC titers, but not PNT titers, correlated inversely with the year of birth, suggesting that ADCC antibody may be more indicative than neutralizing antibody of differences between naturally and vaccine-acquired immunity. These data suggest a possible role for ADCC in protection or recovery from measles.

Adult↗
PubMed1993

WIN 54954 treatment of mice infected with a diabetogenic strain of group B coxsackievirus.

The therapeutic efficacy of an experimental antiviral agent, WIN 54954, was evaluated in a mouse model in which infection by coxsackievirus B4 (CVB4) strain E2 was followed by diabetes mellitus. Male CD1 mice (age, 5 weeks) were inoculated with 10(4) PFU of CVB4. WIN 54954 was administered orally via gavage tube in a dose of either 5 or 50 mg/kg of body weight per day. Treatment was initiated on the day of inoculation and was continued for 10 days. Control animals received the xanthan gum carrier only. At 3 days postinoculation (p.i.), the mean titer of virus in the pancreas was found to be significantly lower in both the high-dose (P < 0.001) and low-dose (P < 0.05) treatment groups compared with that in the controls. Furthermore, islet histologic abnormalities were significantly less common in the high-dose group (P < 0.02) than in the controls. At 7 weeks p.i., both fasting and 1-h postprandial glucose levels in blood were significantly lower for both the high-dose (P < 0.001) and the low-dose (P < 0.01) treatment groups than in controls. The proportion of mice with persistent viral RNA in the pancreas at this time, as detected by polymerase chain reaction, was significantly reduced in the high-dose treatment group (4 of 11 mice) compared with that in the controls (7 of 8 mice). When mice received 50 mg of WIN 54954 per kg daily beginning at either 48 or 72 h postinoculation, the titers in the pancreas were again significantly reduced at 3 days p.i. compared with those in the controls (P < 0.01 and P < 0.05, respectively). Thus, WIN 54954 effectively reduces virus replication and islet histologic changes acutely and decreases, at 7 weeks, both the metabolic alteration associated with diabetes mellitus and the incidence of detectable viral RNA in the pancreas.

Animals↗