A look at the future of pediatric therapeutics: an investigator's perspective of the new pediatric rule.
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Anti-Infective Agents↗
Biomedical subjects
J D Connor
Publications and source records attributed to J D Connor.
Simple high-performance liquid chromatography method for the simultaneous determination of serum caffeine and paraxanthine following rapid sample preparation.
A simple reversed-phase high-performance liquid chromatography (HPLC) method for the simultaneous determination of caffeine and paraxanthine in human serum is described. Serum proteins are precipitated with perchloric acid and the resulting supernatant neutralized for direct injection onto an HPLC column. The method uses a phosphate-methanol mobile phase (85:15, v/v) at pH 4.9 with a flow-rate of 1.75 ml/min and quantitation is by UV absorbance at 274 nm. Elution times are approximately 18 min for caffeine and 8 min for paraxanthine. Theobromine and theophylline have elution times of 5.4 and 9.4 min and do not interfere in the assay. The intra-assay and between-assay means for precision and accuracy for both drugs are: 4.5% C.V. and 3.3% deviation. The sensitivity of the method is 50 ng/ml for each drug.
Caffeine↗
Evaluation of PCR assays in presence of antibody to thermostable DNA polymerases for detection of microbial agents: avoiding false negative results for specimen containing low-titer agent.
The serial low-titer specimens of Influenza A virus and Adeno virus type 7 were tested for the presence of virus specific genes by PCR based on Tth DNA polymerase and by that based on Taq DNA polymerase, in the absence and presence of antibody to the respective DNA polymerases. Increased product DNA synthesis and higher sensitivity of detection were observed in the presence of antibody compared to those in the absence of antibody. 10- to 100- fold lower titer specimen of Influenza A virus and 10-fold lower titer specimen of Adeno virus could be detected in the presence of antibody than those detected in the absence of antibody to the appropriate DNA polymerase, in a PCR.
Adenoviruses, Human↗
Weekly oral azithromycin as prophylaxis for agents causing acute respiratory disease.
Since the 1950s the U.S. military has used intramuscular injections of benzathine penicillin G (BPG) to control outbreaks of respiratory disease. In an effort to find an alternative prophylaxis, a randomized field trial was conducted among 1,016 male U.S. Marine trainee volunteers at high risk for respiratory disease. Participants were evaluated for evidence of acute respiratory infection by serological tests on pretraining and posttraining sera (63 days apart). Oral azithromycin prophylaxis (500 mg/w) outperformed BPG, preventing infection from Streptococcus pyogenes (Efficacy [E] = 84%; 95% confidence interval [CI], 63%-93%), Streptococcus pneumoniae (E = 80%; 95% CI, 50%-92%), Mycoplasma pneumoniae (E = 64%; 95% CI, 25%-83%), and Chlamydia pneumoniae (E = 58%; 95% CI, 15%-79%) in comparison with results in a no-treatment group. Azithromycin group subjects reported few side effects and less respiratory symptoms than the BPG and no-treatment groups. According to serological tests, oral azithromycin is an effective alternative prophylaxis to BPG for military populations.
Administration, Oral↗
Effect of inhibitors in clinical specimens on Taq and Tth DNA polymerase-based PCR amplification of influenza A virus.
Fifteen randomly selected nasopharyngeal (NP) swab specimens (culture-negative for influenza A virus) were spiked with influenza A virus and the nucleic acids were extracted and subjected to PCR amplification with Thermus aquaticus (Taq) and T. thermophilus (Tth) DNA polymerases. Products of the expected size, and giving equivalent band intensities, were obtained from four specimens with both polymerases. Fox six specimens, less products were obtained with Taq DNA polymerase than with Tth DNA polymerase. Products were detected from five NPs only by PCR with Tth DNA polymerase. The transport medium and the calcium alginate swab fibre of the specimens were shown not to be the source of the inhibitors. The incorporation of 32P-dCTP into cDNA, and the yield of PCR products of cDNA made from control RNA template (purified from H2O spiked virus suspension) were decreased in the presence of inhibitory extracts, showing that both the reverse transcription (RT) and PCR steps in amplification with Taq DNA polymerase were sensitive to the inhibitors. In contrast, Tth DNA polymerase was more resistant to the inhibitors and viral nucleic acid from all the specimens examined could be amplified and detected in a single step by RT-PCR with Tth DNA polymerase.
DNA, Complementary↗
Differentiation and characterization of enteroviruses by computer-assisted viral protein fingerprinting.
We have developed and standardized a computerized method for the typing and characterization of enteroviruses with radiolabeled viral protein fingerprints. Enteroviral proteins were radiolabeled with [35S]methionine during growth in cell culture and were then separated by polyacrylamide gel electrophoresis. The dried gel was scanned, and from the resulting computer image (which resembled an autoradiogram) protein patterns were computer extracted and stored in a database. The enterovirus database contained community and prototype strains belonging to 20 different enteroviral serotypes. Each serotype has a discrete protein pattern, and the most important pattern differences for determining each type are in the region of the viral capsid proteins VP1, VP2, and VP3. When the database was challenged with 148 clinical enterovirus strains, 144 (97%) were correctly identified by using the correlation coefficient as a quantitative measure of relatedness between two patterns. This method can identify a type in a single test and represents a practical alternative to virus neutralization because it is less expensive, is much faster (3 rather than 10 days), and does not rely on any virus-specific reagents. The results also show that most of the strains currently isolated from the community have protein patterns different from those of their older prototype strains. Viral protein fingerprinting is an evolving, dynamic system for the typing and characterization of enteroviruses. The method is appropriate for use in clinical virology and reference laboratories for the typing of enteroviruses, for the study of the epidemiology of enteroviruses, and for surveillance of enteroviruses.
Capsid↗
Optimized PCR amplification of influenza A virus RNA using Tth DNA polymerase, incorporating uracil N glycosylase (UNG) in a single tube reaction.
An optimized reaction condition for amplification of influenza A virus RNA, by thermus thermophilus (Tth) DNA polymerase-based PCR, incorporating uracil N glycosylase (UNG) and dUTP in the reaction has been determined. dUTP could not be substituted for all dTTP sites when UNG was present in the reaction. The relative concentration of dUTP and dTTP has been optimized for allowing amplification of the target RNA. It has been verified that the amplified product DNA had sufficient dUTP and was digestable by UNG. Using the optimized reaction condition, influenza A virus-specific DNA fragment could be amplified and detected in 15 of 15 culture positive (for influenza A virus) nasopharyngeal specimens.
DNA Glycosylases↗
A phase-I study of the safety, pharmacokinetics, and antiviral activity of combination didanosine and ribavirin in patients with HIV-1 disease. AIDS Clinical Trials Group 231 Protocol Team.
A phase-I study was conducted to examine the safety, pharmacokinetics, and activity of combination 2',3'-dideoxyinosine (ddI) and ribavirin against human immunodeficiency virus type 1 (HIV-1)-positive individuals with CD4+ cell counts of < or = 500/microliter. Nineteen patients were enrolled into the study in which ddI monotherapy (200 mg p.o.b.i.d.) was administered for the first 4 weeks, followed by the coadministration of ribavirin (600 mg p.o.q.d.) and ddI (200 mg p.o.b.i.d.) for 8 or 20 additional weeks. The combination regimen was safe and well tolerated. Three patients did not complete 12 weeks of the study because of adverse events or voluntary withdrawal. The pharmacokinetic studies performed at weeks 4, 6, and 12 on specimens collected from the 15 individuals who completed 12 weeks of therapy revealed no pharmacokinetic interaction between ddI and ribavirin. A significant decline from baseline in HIV-1 titer as measured by quantitative HIV-1 culture was detected both during the ddI-monotherapy phase (week 4, p < 0.001) and during the combination-therapy ddI + ribavirin phase (week 12, p < 0.001); the median drop observed was 0.90 log10 at week 4 and 0.92 log10 at week 12. While the addition of ribavirin did not result in further reductions in viremia in the following weeks on study treatment, 13 (81%) of the 16 patients had at least a -0.5 log10 change in viral titer at week 12. The median decline in plasma viral RNA was 0.68 log10 at week 4(p < 0.001) and 0.67 log10 at week 12 (p = 0.005). CD4+ cell counts increased above baseline significantly during the ddI-monotherapy phase of the study (p = 0.0038). The median increase was +26 cells/mm3 at week 4 and +11 cells/mm3 at week 12; for patients who remained on treatment through 24 weeks, the median CD4+ cell count increase was +10 cells/mm3. The L74V ddI resistance-conferring HIV-I reverse-transcriptase mutation emerged in 53% of the patients. Patients with non-syncytium-inducing HIV variants demonstrated greater responses to treatment with larger decreases in virus load and greater increases in CD4+ cell count. Our results reveal that the combination of ddI and ribavirin in HIV-positive patients is safe, well tolerated, without adverse pharmacologic interaction, and associated with significant and sustained declines in virus load over 12 weeks of therapy.
Adult↗
Simple reversed-phase high-performance liquid chromatography quantitation of ganciclovir in human serum and urine.
A fast, simple, and cost-effective HPLC method for the quantitation of the antiviral drug ganciclovir is described. The serum samples are extracted with perchloric acid and neutralized with potassium phosphate buffer, and urine samples are diluted with distilled water. A reversed-phase column with isocratic elution by 15 mM potassium phosphate buffer (pH 2.5) containing 0.25% acetonitrile is used to separate ganciclovir; quantitation is by UV absorbance at 254 nm. Total turnaround time is 22 min; more than 3000 samples can be run on a single column without loss of peak quality. The limit of quantitation is 0.05 micrograms/ml. Recoveries varied from 91 to 107% with coefficients of variation ranging from 0.387 to 7.95%.
Antiviral Agents↗
Liposome-encapsulated (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine for long-acting therapy of viral retinitis.
The effect of liposome-encapsulated (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine (HPMPC; cidofovir) was evaluated as prophylaxis in a rabbit model of experimentally induced retinitis caused by preretinal inoculation of herpes simplex virus type 1 (HSV-1). Cidofovir (100 micrograms) in liposomes (0.1 mL) was injected intravitreally 10-120 days before retinal inoculation with HSV-1. Twenty-two of 26 eyes pretreated with liposome-encapsulated cidofovir 10-60 days before HSV-1 inoculation were protected from experimentally induced retinitis, and 2 of 5 eyes pretreated 120 days before inoculation were protected. Intravitreal levels of cidofovir were low (0.7 microgram/mL) but detectable 120 days after injection. One 100-micrograms intravitreal injection of liposome-encapsulated cidofovir appears to have a remarkably potent and prolonged (up to 4 months) antiviral effect in this experimental model of HSV-1 retinitis. Since HPMPC is even more potent against cytomegalovirus than HSV-1, liposome-encapsulated cidofovir may prove to be effective local therapy for AIDS patients with cytomegalovirus retinitis.
Animals↗
Clinical and laboratory characteristics of a large cohort of symptomatic, human immunodeficiency virus-infected infants and children. AIDS Clinical Trials Group Protocol 152 Study Team.
BACKGROUND: A large cohort of antiretroviral therapy-naive, symptomatic, HIV-infected children were enrolled into a controlled therapeutic trial (AIDS Clinical Trials Group Protocol 152), providing an opportunity to describe their clinical and laboratory characteristics and determine age-related distinctions. METHODS: Study entry evaluations for 838 of 839 enrolled children were analyzed. Weight, head circumference (if < 30 months of age), neuroradiologic imaging of the head, developmental or cognitive status and neurologic examination were assessed. Laboratory studies included hemoglobin, absolute neutrophil count, CD4 cell count, serum amylase, alanine aminotransaminase, p24 antigen and HIV blood culture. Data were categorized by age (3 to < 12 months, 12 to < 30 months, 30 months to 6 years and > or = 6 years). RESULTS: Younger children had significantly higher rates of abnormalities before antiretroviral therapy, especially factors relating to growth and neurologic or cognitive function. Lower CD4+ cell counts and percentages as well as a positive serum p24 antigen correlated with lower weight-for-age Z scores and developmental indices. CONCLUSIONS: These data provide a description of the clinical characteristics of HIV-infected US children at the time antiretroviral therapy is initiated for HIV-related symptoms. The high rate of abnormalities of growth, development and cognitive ability that were observed in children < 30 months of age demonstrates that treatment strategies should be developed for earlier intervention.
AIDS-Related Opportunistic Infections↗
Health care worker exposure to aerosolized ribavirin: biological and air monitoring.
Aerosolized ribavirin is administered frequently to treat severe respiratory syncytial virus infections. The drug's potential reproductive effects in occupationally exposed workers remains a concern among health care workers. In this evaluation, we measured urinary ribavirin concentrations in occupationally exposed health care workers. Ribavirin was detected in 16 of 26 (62%) post-work-shift urine samples that had been provided by nurses, and in five of 22 (23%) post-work-shift urine samples that had been provided by respiratory therapists (range, < 0.01 to 0.22 mumol/L). We also measured airborne ribavirin concentrations in the personal breathing zones of nurses. Ventilators and other administration units that were enclosed by an aerosol containment tent produced significantly lower airborne ribavirin exposures than administration units without a containment tent did (range, < 2.5 to 78 micrograms/m3). On the basis of this and other evaluations of airborne ribavirin concentrations, we recommend using aerosol containment systems with all types of ribavirin administration units except mechanical ventilators.
Adult↗
Pharmacokinetic, safety, and antiviral profiles of oral ganciclovir in persons infected with human immunodeficiency virus: a phase I/II study. AIDS Clinical Trials Group, and Cytomegalovirus Cooperative Study Group.
A phase I/II study evaluated the pharmacokinetics, tolerability, and antiviral activity of oral ganciclovir in persons infected with human immunodeficiency virus (HIV). Oral bioavailability ranged from 2.6% to 7.3%. The mean maximum serum concentration achieved at 1000 mg every 8 h was 1.11 micrograms/mL, and mean trough level was 0.54 microgram/mL. The time to maximum serum drug concentration was 1.0-2.9 h, with a serum half-life of 3.0-7.3 h, suggesting prolonged oral absorption. Serious adverse events were uncommon. Decreased cytomegalovirus (CMV) shedding was observed from all sites. The median days (by dosage) to retinitis progression assessed by retinal examination after initiation of oral ganciclovir were 62 (1000 mg every 8 h), 148 (500 mg every 3 h), 75 (750 mg every 3 h), 148 (1000 mg every 3 h), and 139 (2000 mg every 8 h). Thus, oral ganciclovir has pharmacokinetic, toxicity, and antiviral profiles that may prove beneficial for both maintenance therapy of CMV retinitis and prevention of CMV disease in HIV-infected persons.
Administration, Oral↗
Intravitreous and plasma concentrations of ganciclovir and foscarnet after intravenous therapy in patients with AIDS and cytomegalovirus retinitis.
This study evaluated intravitreous and plasma ganciclovir and foscarnet concentrations after intravenous administration in AIDS patients with cytomegalovirus (CMV) retinitis and retinal detachment. Undiluted vitreous samples were prospectively obtained from 60 eyes (52 patients) at the time of pars plana vitrectomy. Thirty-three plasma samples (from 27 patients in the initial group of 52) were obtained simultaneously during surgery on 33 eyes. High-pressure liquid chromatography showed the mean vitreous ganciclovir concentrations in patients on induction and maintenance therapy were, respectively, 4.74 +/- 1.49 microM (n = 24) and 3.29 +/- 1.84 microM (n = 30; P = .005). Simultaneous plasma ganciclovir concentrations were less than the vitreous concentrations in 78% of the patients. The mean intravitreous foscarnet concentrations in patients receiving induction dosages were 189 +/- 177 microM (n = 5) versus 163 +/- 167 microM (n = 4; P > .20) for those receiving maintenance therapy. The foscarnet vitreous plasma concentration ratio averaged 1.43. Current drugs and doses for CMV retinitis result in borderline or progressively subtherapeutic concentrations.
Acquired Immunodeficiency Syndrome↗
Effect of partial retinal destruction and gliosis on the intravitreal pharmacokinetics of HPMPC.
PURPOSE: Intravitreal HPMPC ([S]-1-[3-hydroxy-2 phosphonylmethoxypropyl cytosine) has a long antiviral effect in patients with cytomegalovirus retinitis. The authors evaluated the pharmacokinetics of intravitreal injections of HPMPC to understand major route of HPMPC elimination in a pigmented rabbit that had undergone scatter laser photocoagulation over half of the retinal surface. METHODS: The authors treated the inferior half of the retina, receiving an average of 605 grade 3 or 4 (gray-white or white) diode laser burns in a scatter fashion in the left eyes of 13 rabbits. After 4 weeks, 13 rabbits received intravitreal injection of HPMPC (100 micrograms in 0.1 mL) in both eyes. Forty-eight hours after injection, unfixed vitreous samples were obtained for high-pressure liquid chromatography analysis. Two rabbits were used for light microscopic examination of diode laser photocoagulated retina with the perfusion fixation. RESULTS: The HPMPC concentration in the vitreous was 5.93 +/- 1.75 micrograms/mL in the laser-treated group and 4.76 +/- 1.2 micrograms/mL in the control group 48 hours after intravitreal HPMPC injection. The difference was statistically different (P = 0.037). CONCLUSIONS: Results showed a higher concentration of intravitreal HPMPC in the eye that had approximately 25% of the retina destroyed by the laser photocoagulation. The higher concentration is likely the result of reduced elimination and a concomitant increase in half-life. This suggests that HPMPC may be eliminated via the retinal route. Eyes with more extensive retinal involvement with human cytomegalovirus may have an even longer duration of action of intravitreal HPMPC. This may lead to modification of dosing regimens.
Animals↗
Therapy of pediatric AIDS.
Therapy of pediatric AIDS utilizes antiretroviral compounds; antibiotic, antifungal, and antiparasitic agents; and both active and passive immunization in a multifactorial approach. Currently, newly diagnosed pediatric AIDS cases are acquired predominantly through vertical transmission from HIV-infected mothers. Pediatric AIDS research is focused on strategies to prevent vertical transmission of HIV infection as well as therapy against opportunistic and progressive HIV disease. Zidovudine remains first-choice therapy for HIV infection and can reduce the rate of vertical transmission of HIV. Didanosine is also approved to treat HIV infection in pediatric AIDS. Other reverse transcriptase inhibitors are under investigation as alternative or combination therapies because of HIV resistance to zidovudine and didanosine. Alternative therapies for opportunistic infections are being investigated. Passive immunity with intravenous immunoglobulin is being reevaluated to determine efficacy in combination with other therapies. Finally, vaccination against usual childhood diseases with standard immunization schedules produces limited immunity, and alternative vaccination protocols warrant further investigation.
AIDS-Related Opportunistic Infections↗
Population differences in ganciclovir clearance as determined by nonlinear mixed-effects modelling.
We examined the pharmacokinetics of ganciclovir in different populations of cytomegalovirus (CMV)-infected patients through the use of nonlinear mixed-effects modelling. As expected, patient weight and estimated creatinine clearance were shown to be important covariates in the serum ganciclovir clearance. Unexpectedly, major differences in ganciclovir clearance between different populations of patients were found. Human immunodeficiency virus (HIV)-infected patients with CMV retinitis cleared ganciclovir 41% faster than HIV-infected patients only shedding CMV into the urine. Solid-organ transplant patients had a serum clearance one-fourth that of HIV-infected patients, even with correction for creatinine clearance. These findings require prospective validation and may have important implications for ganciclovir dosing in different populations of CMV-infected patients.
AIDS-Related Opportunistic Infections↗
The influence of endogenous and exogenous sex hormones in adolescents with attention to oral contraceptives and anabolic steroids.
The endogenous sex hormones produce dispositional changes in the developing child as well as imparting unique male and female dispositional patterns. Age-related changes have been observed for digoxin disposition and caffeine and theophylline metabolism. These age-related dispositional changes have led to age-dependent dosing recommendations. Studies with caffeine and antipyrine indicate that this change in drug disposition occurs over a short period of time, is seen earlier in girls than in boys, and is related to pubertal (Tanner) stage and the "growth spurt". Significant changes in endogenous sex hormone concentrations occur during the menstrual cycle and during pregnancy, leading to alterations in drug binding, distribution, and clearance. Oral contraceptives (OCs) inhibit the metabolism of certain drugs resulting in toxicity or lack of efficacy. Rifampin induces the OC metabolism, resulting in decreased clinical effectiveness. Most studies did not examine these kinetic and dynamic interactions between adult and adolescent users. It is estimated that there are over 45 anabolic steroid compounds available for abuse by athletes, and their use is increasing among male and female adolescents. Although the adolescent is at increased risk of developing adverse effects from these agents, a systematic evaluation of the long-term effects of anabolic steroid abuse has not been undertaken in this population. Further research is needed regarding the influence of endogenous and exogenous hormones on adolescent drug kinetics and dynamics. Because of their frequency of use among adolescents, OCs and anabolic steroids require particular emphasis.
Adolescent↗