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Biomedical subjects

I W Fong

Publications and source records attributed to I W Fong.

At least 19 recordsLinked to original sources

Active immunization of patients with HIV infection: a study of the effect of VaxSyn, a recombinant HIV envelope subunit vaccine, on progression of immunodeficiency.

Infection with the human immunodeficiency virus (HIV) leads to a progressive immunodeficiency characterized by decreasing levels of CD4+ T lymphocytes. VaxSyn, a vaccine based on the recombinant envelope glycoprotein subunit (rgp160) of HIV-1IIIB, was used to immunize HIV-infected patients to determine whether its administration was beneficial with respect to slowing disease progression. A 3-year multicenter, randomized, placebo-controlled, double-blinded, efficacy and safety trial of repeated immunization with VaxSyn was used to evaluate the long-term impact on the progression of immunodeficiency. VaxSyn in alum, or alum alone, was given to 278 HIV-infected asymptomatic individuals with initial CD4 counts of > or =500 cells/mm3. Clinical findings, the CD4 count, and both virological and immunological parameters were followed. No significant differences were observed between the treatment and placebo control groups in rate of CD4 T cell decline, time to initiation of antiretroviral therapy, incidence of opportunistic infections, HIV RNA plasma viremia, HIV viral infectivity as measured by quantitative HIV coculture assay, and death. This study revealed no effect on either clinical or laboratory virological parameters from the administration of VaxSyn.

AIDS Vaccines

Integrative aspects of a human model of endotoxemia.

The production of tumor necrosis factor (TNF)-alpha is a key step in the response to sepsis and has powerful local and systemic effects on the host. These systemic responses include a complex cascade of centrally mediated endocrine and neural responses. An integrative model of these regulatory cytokine-neuroendocrine interactions in humans is presented. The rapid kinetics of these responses are illustrated by data showing the response of normal human subjects to experimental endotoxemia. Appreciation of the integrative biology of the in vivo response to experimental endotoxemia can provide a framework for the design of experiments aimed at examining the effects of physical training paradigms on particular cytokine and neuroendocrine pathways.

Adrenocorticotropic Hormone

Chlamydia pneumoniae, cytomegalovirus, and herpes simplex virus in atherosclerosis of the carotid artery.

BACKGROUND: Chlamydia pneumoniae and the herpes viruses cytomegalovirus (CMV) and herpes simplex virus type 1 (HSV-1) have been associated with human atherosclerosis in seroepidemiological and separate histopathological studies. We investigated the concurrent presence of these microorganisms in patients undergoing carotid endarterectomy. METHODS AND RESULTS: Endarterectomy specimens from 76 patients with carotid artery stenosis were stained for C. pneumoniae, CMV, and HSV-1 particles with specific IgG monoclonal antibodies by the avidin-biotin-peroxidase method. IgG antibodies to CMV and C. pneumoniae were also measured in the serum. These were correlated with plaque morphology and the presence of the microorganisms in the atherosclerotic plaques. C. pneumoniae was detected in 54 (71%) (95% confidence interval [CI], 59.5% to 80.9%), CMV was detected in 27 (35.5%) (CI, 24.9% to 47.3%), and HSV-1 was detected in 8 (10.5%) (CI, 4.7% to 19.7%) versus none of 20 (0%) control normal carotid artery and aortic tissue (autopsy) specimens (CI, 0% to 16.8%) (P<.001 for CMV and C. pneumoniae). At least one microorganism was detected in 59 of the specimens (77.6%) (CI, 66.6% to 86.4%), with a single microorganism present only in 35 (46%), two microorganisms present in 18 (23.7%) (CI, 14.7% to 34.8%), and all three present in 6 (7.9%) (CI, 3.0% to 16.4%). Atherosclerotic plaques with thrombosis were more likely to have C. pneumoniae (80.4%) or CMV (57.8%) than were plaques without thrombosis (56.7% and 16.7%, respectively; P=.04 and .007). There was no correlation between the presence of CMV and C. pneumoniae in the atherosclerotic vessels and serum antibody titers. CONCLUSIONS: C. pneumoniae and CMV are commonly detected in atherosclerotic plaques of the carotid arteries, but their presence cannot be predicted by measuring serum antibodies. The presence of these microorganisms may predispose to a greater risk of thrombosis in the plaques, but further studies are needed to confirm this observation.

Adult

The effect of exercise on lymphocyte redistribution and leucocyte function in asymptomatic HIV-infected subjects.

This study was undertaken to examine the responsiveness of circulating leucocyte and lymphocyte populations to the physiological demands of exercise in asymptomatic HIV-infected subjects with CD4+ counts greater than 500/microliter. Thirteen subjects infected with HIV and 14 control subjects underwent 20 min of defined moderate exercise at estimated 65% of their maximal ventilatory capacity on a bicycle ergometer. Blood samples were obtained for serum cortisol, norepinephrine, lymphocyte subsets (CD4, CD8, CD19, CD16-CD56), and phagocytic function at rest immediately after exercise and 20 min following the cessation of the exercise. The HIV-infected subjects had increased circulating concentrations of CD8 cells (p = .007) and CD16-CD56+ NK cells (p = .02) in response to the exercise, whereas the control group did not. There was a greater increase in monocyte respiratory burst activity following recovery from exercise in the control subjects (p = .016) but not in the HIV-infected subjects. The control subjects experienced an increase in serum cortisol in response to the exercise (p = .006), but the HIV-infected subjects did not. Our results show that the changes in the distribution and function of circulating leucocytes and adrenal neuroendocrine responses to moderate exercise differ in asymptomatic HIV-infected and control subjects.

Adult

The efficacy of exit site povidone-iodine ointment in the prevention of early peritoneal dialysis-related infections.

Infections are the main complications of peritoneal dialysis, and currently there is no established method for prevention. A prospective, randomized, single-blind study was performed to evaluate the efficacy of regular application of povidone-iodine ointment at the catheter site (during the entire time on the study) in peritoneal dialysis. One hundred twenty patients were randomized; three were excluded for not completing the study. Sixty-one patients received application of povidone-iodine and 56 patients received standard care. Povidone-iodine ointment was effective in delaying infectious complications, with a lower proportion of treated patients having infections (exit site and peritonitis) within 140 days of starting dialysis compared with the controls (P = 0.04, Wilcoxon test). This protective benefit was lost after 140 days on dialysis. Staphylococcus aureus infections developed in only two (3.3%) of the treated patients compared with 10 (21.4%) of the controls (P = 0.009), despite the higher rate of S aureus nasal carriage in the treated group (22 of 61 patients [36%] v 14 of 56 patients [25%]).

Adult

Rabbit model for Chlamydia pneumoniae infection.

A rabbit model was established for Chlamydia pneumoniae infection that may be helpful to understand the pathogenesis of disease in humans. Twelve, pathogen-free, 1-month-old New Zealand White rabbits were inoculated with 1.0 x 10(7) to 5.0 x 10(7) CFU of purified C. pneumoniae (ATCC strain VR 1310) via the nasopharynx (1 rabbit died immediately postinoculation, and 11 were available for study). Five controls were inoculated with the carrier buffer. Ten of the 11 study rabbits demonstrated serological evidence of acute infection (immunoglobulin G antibodies, 1:8 to > 1:16), with the weakest response at 7 days and the strongest response at 28 days, whereas none of the controls showed any seroconversion. Study animals were sacrificed in batches of three, on days 7, 14, 21, and 28, but controls were sacrificed on days 7 and 28. Two-thirds of the animals demonstrated evidence of bronchiolitis and pneumonia on days 7 and 14 and resolution by day 21. Two study rabbits demonstrated, on histology, early and intermediate lesions of atherosclerosis: one animal (day 7) showed the accumulation of foamy macrophages (fatty streak) in the arch of the aorta, and the other animal (day 14) showed spindle cell proliferation of smooth muscle cells (intermediate lesion). Focal periaortitis was seen in the same animal (day 7). C. pneumoniae elementary bodies were demonstrated by immunocytochemical stain in the lungs (n = 2), liver (n = 3), spleen (n = 5), and aorta (n = 2), one of which corresponded to the intermediate lesion. C. pneumoniae was cultured from the lungs (n = 2), liver (n = 2), spleen (n = 2), and aortic arch (n = 1). All histopathological, immunocytochemical, and cultural studies were negative in the controls. Hence, the rabbit provides a useful animal model for the study of C. pneumoniae infection and its complications, particularly atherosclerosis.

Animals

Asymptomatic oral carriage of Candida albicans in patients with HIV infection.

OBJECTIVE: To assess the relationship of asymptomatic carriage of Candida albicans and clinically apparent thrush in patients with HIV infection. DESIGN: Prospective, longitudinal, controlled study. SETTING: The HIV clinic at St. Michael's Hospital, University of Toronto. PARTICIPANTS: One hundred and twenty-seven patients with HIV-infection were divided into 3 groups according to the CD4+ lymphocyte count, and 37 healthy volunteers served as controls. INTERVENTIONS: Determination of blood type, baseline CD4+ lymphocyte count in patients with HIV infection, and immunophenotyping. Samples of saliva (2 mL) were obtained from each patient and control. MAIN OUTCOME MEASURES: Carrier status, clinical presence of thrush, the association between carriage of C. albicans and blood type, secretor status and history of oral infection. RESULTS: In patients with HIV infection and C albicans colonization no correlation was found with blood type or secretor status of blood group antigen in the saliva. The frequency of oral carriage of yeast was greater in patients infected with HIV than in controls, but the difference was not significant for asymptomatic subjects with a CD4+ lymphocyte count greater than 500/microL. Persistent carriage of yeast and development of clinical thrush were associated with lower CD4+ counts. Clinical thrush developed only in patients with persistent asymptomatic carriage of C. albicans and CD4+ counts less than 500/microL. CONCLUSION: The greater risk of oral colonization with C. albicans in patients with HIV infection partly explains the high prevalence of thrush found in this group.

Adolescent

A comparison of two regimens for the treatment of Mycobacterium avium complex bacteremia in AIDS: rifabutin, ethambutol, and clarithromycin versus rifampin, ethambutol, clofazimine, and ciprofloxacin. Canadian HIV Trials Network Protocol 010 Study Group.

BACKGROUND: Bacteremia with the Mycobacterium avium complex is common in patients with the acquired immunodeficiency syndrome (AIDS), but the most effective treatment for this infection remains unclear. METHODS: We randomly assigned 229 patients with AIDS and M. avium complex bacteremia to receive either rifampin (600 mg daily), ethambutol (approximately 15 mg per kilogram of body weight daily), clofazimine (100 mg daily), and ciprofloxacin (750 mg twice daily) (the four-drug group) or rifabutin (600 mg daily), ethambutol (as above), and clarithromycin (1000 mg twice daily) (the three-drug group). In the three-drug group the dose of rifabutin was reduced by half after 125 patients were randomized, because 24 of 63 patients had uveitis. RESULTS: Among 187 patients who could be evaluated, blood cultures became negative more often in the three-drug group than in the four-drug group (69 percent vs. 29 percent, P<0.001). Among patients treated for at least four weeks, the bacteremia resolved more frequently in the three-drug group (78 percent vs. 40 percent, P<0.001). In the three-drug group, bacteremia resolved more often with the 600-mg dose of rifabutin than with the 300-mg dose (P=0.025), but the latter regimen was more effective than the four-drug regimen (P<0.05). The median survival was 8.6 months in the three-drug group and 5.2 months in the four-drug group (P = 0.001). The median Karnofsky performance score was higher in the three-drug group than in the four-drug group from week 2 to week 16 (P<0.05). Mild uveitis developed in 3 of the 53 patients receiving the 300-mg dose of rifabutin, an incidence about one quarter that observed with the 600-mg dose (P<0.001). CONCLUSIONS: In patients with AIDS and M. avium complex bacteremia, treatment with the three-drug regimen of rifabutin, ethambutol, and clarithromycin leads to resolution of the bacteremia more frequently and more rapidly than treatment with rifampin, ethambutol, clofazimine, and ciprofloxacin, and survival rates are better.

AIDS-Related Opportunistic Infections

The natural history of progressive multifocal leukoencephalopathy in patients with AIDS. Canadian PML Study Group.

Progressive multifocal leukoencephalopathy (PML) is usually a fatal neurological disease. The natural history of PML in patients with human immunodeficiency virus infection was analyzed. The correlations between CD4+ lymphocyte count, previous diagnosis of AIDS, treatment with cytarabine, and survival time are reported for 28 individuals for whom the diagnosis of PML was confirmed by histopathologic examination. For 16 patients (57%), PML was the AIDS-defining illness. For these 16 patients, the mean (+/- SD) survival time after presentation was 7.5 +/- 7.6 months (range, 1-31 months), whereas that for the 12 patients (43%) for whom AIDS was previously diagnosed was 3.2 +/- 2.8 months (range, 1-11 months) (P = .01). The overall mean (+/- SD) CD4+ cell count was 85 +/- 82/mm3 (range, 12-349/mm3). The mean (+/- SD) survival time for patients with CD4+ cell counts of > or = 90/mm3 at the time of presentation was 9.4 +/- 8.7 months, while that for patients with CD4+ cell counts of < 90/mm3 at the time of presentation was 3.6 +/- 1.8 months (P = .03). The nine patients did not benefit from treatment with cytarabine.

Acquired Immunodeficiency Syndrome

The value of a single amphotericin B bladder washout in candiduria.

The efficacy of single amphotericin B bladder washout was assessed, and the source of infection was sought, in 47 patients with 62 separate episodes of candiduria. After a single bladder washout, 44 of 62 (71%) candiduria episodes cleared and none of these patients had evidence of invasive disease or kidney infection. Ten (56%) of 18 patients with persistent candiduria had no evidence of invasive disease or kidney infection at autopsy or clinically. The sensitivity of a positive urine culture for Candida spp. after a single amphotericin B bladder washout in predicting kidney infection or invasive candidiasis was 100% (CI = 63-100%); but the specificity was only 81% (CI = 47-100%) and the positive predictive value only 44%.

Administration, Intravesical

Pharmacokinetics of trimethoprim-sulfamethoxazole in critically ill and non-critically ill AIDS patients.

Current dosage regimens of trimethoprim-sulfamethoxazole used to treat Pneumocystis carinii pneumonia in AIDS patients have been based on data from healthy subjects or patients without AIDS. The clearance and absorption characteristics of the drugs may potentially be different between patients with and without AIDS. This study was conducted to assess the pharmacokinetics of trimethoprim-sulfamethoxazole in critically ill and non-critically ill AIDS patients treated for P. carinii pneumonia. Patients received trimethoprim at 15 mg/kg of body weight and sulfamethoxazole at 75 mg/kg of body weight daily intravenously in three to four divided doses and were switched to the oral route when the regimen was tolerated. Serum samples for determination of drug concentrations were obtained over 12 h after intravenous and oral dosing. The pharmacokinetics of trimethoprim and sulfamethoxazole were compared in eight critically ill versus nine non-critically ill male patients and were as follows, respectively: clearance, 1.88 +/- 0.44 versus 1.73 +/- 0.64 ml/min/kg for trimethoprim and 0.40 +/- 0.12 versus 0.34 +/- 0.11 ml/min/kg for sulfamethoxazole; volume of distribution, 1.6 +/- 0.5 versus 1.5 +/- 0.5 liters/kg for trimethoprim and 0.5 +/- 0.3 versus 0.4 +/- 0.1 liters/kg for sulfamethoxazole; and half-life, 10.9 +/- 7.4 versus 11.3 +/- 4.0 h for trimethoprim, and 15.5 +/- 9.5 versus 14.3 +/- 4.7 h for sulfamethoxazole. No significant differences (P > 0.05) were observed between patient groups, although there was wide intersubject variability. Absorption appeared to be similar between the critically ill and non-critically patients: bioavailability was 97.5% +/- 22.4% versus 101.8% +/- 22.7% for trimethoprim and 86.2% +/- 17.9% versus 99.1% +/- 20.5% for sulfamethoxazole, respectively. Because of the similar pharmacokinetics of trimethoprim-sulfamethoxazole in critically ill and non-critically ill AIDS patients, the two groups of patients may receive similar dosages. Dosage adjustment does not appear to be required when switching from the intravenous to the oral route.

AIDS-Related Opportunistic Infections

Effects of an acidic beverage (Coca-Cola) on absorption of ketoconazole.

Absorption of ketoconazole is impaired in patients with achlorhydria. The purpose of this study was to determine the effectiveness of a palatable acidic beverage (Coca-Cola Classic, pH 2.5) in improving the absorption of ketoconazole in the presence of drug-induced achlorhydria. A prospective, randomized, three-way crossover design with a 1-week wash-out period between each treatment was employed. Nine healthy nonsmoking, nonobese volunteers between 22 and 41 years old were studied. Each subject was randomized to receive three treatments: (A) ketoconazole 200-mg tablet with water (control), (B) omeprazole (60 mg) followed by ketoconazole (200 mg) taken with water, and (C) omeprazole (60 mg) followed by ketoconazole (200 mg) taken with 240 ml of Coca-Cola Classic. The pH values of gastric aspirates were checked after omeprazole was administered to confirm attainment of a pH of > 6. Multiple serum samples were obtained for measurements of ketoconazole concentrations by high-pressure liquid chromatography. The mean area under the ketoconazole concentration-time curve from zero to infinity for the control treatment (17.9 +/- 13.1 mg.h/liter) was significantly greater than that for treatment B (3.5 +/- 5.1 mg.h/liter; 16.6% +/- 15.0% of control). The mean peak concentration was highest for the control treatment (4.1 +/- 1.9 micrograms/ml), for which the mean peak concentration showed a significant increase over that for treatment B. The absorption of ketoconazole was reduced in the presence of omeprazole-induced achlorhydria. However, drug absorption was significantly increased, to approximately 65% of the mean for the control treatment, when the drug was taken with an acidic beverage, such as Coca-Cola.

Achlorhydria

Diagnostic value of detecting JC virus DNA in cerebrospinal fluid of patients with progressive multifocal leukoencephalopathy.

JC virus DNA was detected by PCR in the cerebrospinal fluid of 17 of 23 (73.9%) patients with confirmed cases of progressive multifocal leukoencephalopathy and 2 of 48 (4.2%) controls without progressive multifocal leukoencephalopathy. The sensitivity and specificity of this PCR were 74 and 95.8%, respectively, while the positive and negative predictive values were 89.5 and 88.5%, respectively.

DNA, Viral

Clarithromycin versus cefaclor in lower respiratory tract infections. The Canadian Bronchitis Study Group.

A randomized study was done to compare the efficacy of clarithromycin 250 mg or 500 mg b.i.d., vs. cefaclor 250 mg or 500 mg t.i.d. for 7-14 d in 197 evaluable patients with lower respiratory tract infection. Ninety-five patients received clarithromycin, 88 with acute bronchitis or exacerbation of chronic bronchitis, and 7 with pneumonia. One hundred and two patients received cefaclor, 86 with bronchitis and 16 with pneumonia. Ten patients (10.5%) in the clarithromycin group did not complete the trial, 5 (5.3%) because of adverse event, and 3 (3.2%) because of clinical failure. Similarly, 11 patients (10.8%) did not complete cefaclor, 2 (2%) because of adverse event, and 7 (6.9%) because of clinical failure. Clinical cure or improvement was observed in 90 (94.7%) of patients on clarithromycin vs. 92 (90.2%) on cefaclor, p = 0.66. Bacteriologic cure was seen in 26/36 patients (72.2%) on clarithromycin vs. 28/40 patients (70%) on cefaclor, p = 0.28. Clarithromycin is just as effective as cefaclor for lower respiratory tract infections and is well tolerated.

Bronchitis

Alcoholism and rapid progression to AIDS after seroconversion.

Rapid progression of infection with human immunodeficiency virus type 1 (HIV-1) to AIDS after seroconversion is rare; it has been associated with coinfection by cytomegalovirus or human T lymphotrophic virus type I. We describe an alcoholic patient whose condition progressed to AIDS 3 months after HIV-1 seroconversion occurred. Culture of peripheral blood mononuclear cells yielded a syncytium-inducing variant of HIV-1. T lymphocytes showed no spontaneous cytotoxic activity against HIV-infected cells, nor could such activity be demonstrated following stimulation with HIV-1 antigen in the presence of recombinant interleukin-2. We hypothesize that our patient's accelerated course was due to alcohol abuse, which may have suppressed T cell function and stimulated HIV replication.

Acquired Immunodeficiency Syndrome

The value of prophylactic (monthly) clotrimazole versus empiric self-treatment in recurrent vaginal candidiasis.

OBJECTIVE: To determine the comparative efficacy and cost benefit of prophylactic monthly (perimenstrual) clotrimazole, versus empiric self-treatment with the same agent at the onset of symptoms in recurrent vulvovaginal candidiasis. DESIGN: Prospective, randomised, open cross-over study of women with proven recurrent vulvovaginal candidiasis. Clinical and microbiological assessments were done every two months for 12 months. SETTING: Women's Clinic of a University Teaching Hospital. SUBJECTS: Twenty-three otherwise healthy, non-pregnant women with greater than four proven episodes of candida vaginitis in the last year were enrolled into the study. INTERVENTION: Patients were randomised to receive: (1) a single dose of prophylactic clotrimazole 500 mg ovule just before or on the last day of the menses each month for 6 months; (2) or a single dose of clotrimazole 500 mg ovule empirically at the onset of symptoms for 6 months. After the first 6 months patients were crossed-over to the opposite regimen. MAIN OUTCOME MEASURES: Symptoms of recurrent vulvovaginitis during each period, and number of clotrimazole ovules used for each 6 month period. The personal preference of the patients for the two different regimens were assessed at the end of study. RESULTS: During the prophylactic 6 months period of the study, 23 patients had 50 episodes of symptomatic vaginitis (mean 2.2 episodes per patient), versus 86 episodes (mean 3.7 episodes/patient) during the empiric self-treatment 6 months period (P = 0.05). However, during the prophylactic period a total of 168 clotrimazole ovules were used (mean 7.3 per patient), versus 84 ovules (mean 3.6 per patient) during the empiric self-treatment period, p < 0.001. The personal preference of the patients for the type of regimen employed were 17 (73.9%) in favour of the empirical treatment, versus 4 (17.4%) in favour of the prophylactic treatment and 2 (8.7%) no personal preference, p < 0.01. CONCLUSION: Empiric self-treatment is more cost-effective and preferable to patients than cyclical monthly prophylactic use of 500 mg clotrimazole vaginal ovules.

Adolescent

The rectal carriage of yeast in patients with vaginal candidiasis.

Reinfection from the lower gastrointestinal tract is a possible source of recurrent vulvo-vaginal candidiasis. A prospective study to assess the prevalence of yeast carriage in various orifices (including the rectum) in controls and patients, and the relationship to acute vaginitis, was conducted. Cultures for yeast were obtained from the mouth, rectum, vulva, and vagina every 1-2 months for 1 y from the patients. The prevalence of yeast carriage in healthy controls was 3/37 (8.1%) from the vulva, vagina, and rectum, and 4/37 (10.8%) from the mouth. In patients, yeast carriage during episodes of vaginitis was: from the vagina, 190/193 (98.4%); from the vulva, 107/193 (55.4%); from the rectum, 93/193 (48.2%); and from the mouth, 52/193 (26.9%). During visits without vaginitis, yeast carriage was lower: in the rectum, 59/587 (10.1%); in the vulva, 53/459 (11.6%); in the vagina, 77/587 (13.1%); and in the mouth, 89/587 (15.2%). Yeast in the lower bowel during symptomatic vaginitis is higher (p = 0.0001) than in controls, but not significantly greater during asymptomatic periods. Recurrence of Candida vaginitis is not dependent on yeast reservoir in the lower gut between symptomatic episodes.

Administration, Intravaginal