A bioactive metallurgical grade porous silicon-polytetrafluoroethylene sheet for guided bone regeneration applications.

The properties of porous silicon make it a promising material for a host of applications including drug delivery, molecular and cell-based biosensing, and tissue engineering. Porous silicon has previously shown its potential for the controlled release of pharmacological agents and in assisting bone healing. Hydroxyapatite, the principle constituent of bone, allows osteointegration in vivo, due to its chemical and physical similarities to bone. Synthetic hydroxyapatite is currently applied as a surface coating to medical devices and prosthetics, encouraging bone in-growth at their surface and improving osseointegration. This paper examines the potential for the use of an economically produced porous silicon particulate-polytetrafluoroethylene sheet for use as a guided bone regeneration device in periodontal and orthopaedic applications. The particulate sheet is comprised of a series of microparticles in a polytetrafluoroethylene matrix and is shown to produce a stable hydroxyapatite on its surface under simulated physiological conditions. The microstructure of the material is examined both before and after simulated body fluid experiments for a period of 1, 7, 14 and 30 days using Scanning Electron Microscopy. The composition is examined using a combination of Energy Dispersive X-ray Spectroscopy, Thin film X-ray diffraction, Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy and the uptake/release of constituents at the fluid-solid interface is explored using Inductively Coupled Plasma-Optical Emission Spectroscopy. Microstructural and compositional analysis reveals progressive growth of crystalline, 'bone-like' apatite on the surface of the material, indicating the likelihood of close bony apposition in vivo.

Assessment of lopinavir pharmacokinetics with respect to developmental changes in infants and the impact on weight band-based dosing.

Improved antiretroviral therapies are needed for the treatment of HIV-infected infants, given the rapid progression of the disease and drug resistance resulting from perinatal exposure to antiretrovirals. We examined longitudinal pharmacokinetics (PK) data from a clinical trial of lopinavir/ritonavir (LPV/r) in HIV-infected infants in whom therapy was initiated at less than 6 months of age. A population PK analysis was performed using NONMEM to characterize changes in lopinavir (LPV) PK relating to maturational changes in infants, and to assess dosing requirements in this population. We also investigated the relationship between LPV PK and viral dynamic response. Age and ritonavir concentrations were the only covariates found to be significant. Population PK of LPV was characterized by high apparent clearance (CL/F) in young infants, which decreased with increasing age. Although younger infants had lower LPV concentrations, the viral dynamics did not correlate with initial LPV exposure. Monte Carlo simulations demonstrated that WHO weight band-based dosing recommendations predicted therapeutic LPV concentrations and provided drug exposure levels comparable to those resulting from US Food and Drug Administration (FDA)-suggested dosing regimens.

Infrequent detection of HIV-1-specific, but not cytomegalovirus-specific, CD8(+) T cell responses in young HIV-1-infected infants.

Early potent combination antiretroviral therapies (ART) for HIV-1 infection can preserve or restore immune function, but control of viral replication early in infection may interfere with the development of HIV-1-specific immune responses. Using an IFN-gamma ELISPOT assay, we evaluated the breadth and intensity of HIV-1-specific CD8(+) T cell responses in 17 vertically infected infants who began ART at 1-23 mo of age. CMV-specific responses were also characterized in three infants coinfected with HIV-1 and CMV. Before ART, HIV-1-specific CD8(+) T cell responses were detected in two of 13 (15%) infants <6 mo of age. HIV-1-specific CD8(+) T cells became undetectable in these two infants after the control of viral replication. Intermittent HIV-1-specific responses were noted in six infants who did not experience durable control of viral replication. In contrast, HIV-1-specific responses were detected before ART in four of four infants >6 mo of age and became persistently undetectable in only one child. CMV-specific CD8(+) T cell responses were persistently detected in all HIV-1 and CMV coinfected infants. In conclusion, HIV-1-specific CD8(+) T cell responses were less commonly detected before therapy in young infants than in older infants. Suppression of viral replication appeared to interfere with the development and maintenance of HIV-1-specific CD8(+) T cell responses. The detection of CMV-specific responses in HIV-1 and CMV coinfected infants suggests a selective defect in the generation or maintenance of HIV-1-specific CD8(+) T cell responses. Therapeutic HIV-1 vaccine strategies in young infants may prolong the clinical benefit of ART by expanding the HIV-1-specific CD8(+) T cell pool.

Gastrostomy tube insertion for improvement of adherence to highly active antiretroviral therapy in pediatric patients with human immunodeficiency virus.

OBJECTIVES: Newer combination antiretroviral therapies used to treat human immunodeficiency virus (HIV)-infected individuals have resulted in dramatic delays in HIV progression, with reduction in mortality and morbidity. However, adherence to highly active antiretroviral therapy (HAART) may be problematic, particularly in HIV-infected children. Reasons for nonadherence include refusal, drug tolerability, and adverse reactions. We assess: 1) the potential benefits of gastrostomy tube (GT) for the improvement of adherence to HAART in HIV-infected children, and 2) the factors that may result in improved viral suppression after GT placement. METHODS: The medical records of 17 pediatric HIV-infected patients, in whom GT was used to improve HAART adherence, were retrospectively reviewed for clinical and laboratory parameters. Each record was reviewed for the period of 1 year before and after GT insertion. The main outcome parameters were virologic (plasma HIV RNA polymerase chain reaction quantification) and immunologic (CD4 cell counts). Documentation of adherence to medications in medical records was also assessed during the study. Parental questionnaires were used to determine GT satisfaction and medication administration times. The Wilcoxon rank sum test was used to assess change in viral load (VL) and CD4 cell percentages. RESULTS: GT was well-tolerated with minor complications, such as local site tenderness, reported by 4 patients (23%). Before GT insertion, only 6 patients (35%) were documented as being adherent, compared with all patients after GT insertion. Ten patients (58%) had >/=2 log(10) VL decline after GT insertion (median: 3.2 log(10)), compared with 7 patients (42%) who had /=2 log(10) VL decline, therapy was changed at the time of or soon after GT insertion (median:.8 months; range: 0-6 months), compared with 7 patients with <2 log(10) VL decline who had therapy changed before GT insertion (median: 3.2 months; range: 1-8 months). Parental questionnaires reported significantly shorter medication administration times after GT insertion, with 70% of patients taking >5 minutes before GT, compared with 0% after GT. Questionnaires indicated satisfaction with GT, with perceived benefits being reduced medication administration time and improved behavior surrounding taking medications. CONCLUSIONS: GT is well-tolerated in pediatric HIV-infected patients and should be considered for selected patients to overcome difficulties with medication administration and to improve adherence. For maximal virologic response, combination therapy should be changed at the time of GT insertion.

Effect of vitamin A therapy on serologic responses and viral load changes after influenza vaccination in children infected with the human immunodeficiency virus.

Vitamin A administered to children infected with the human immunodeficiency virus before influenza vaccination in a double-blind randomized study did not enhance vaccine serologic responses but did dampen the increase in the human immunodeficiency virus viral load 14 days after immunization (vitamin A, decrease of 0.13 +/- 0.09 log(10) copies/mL; placebo, increase of 0.14 +/- 0.08, P =.02).

Adrenal suppression in children with the human immunodeficiency virus treated with megestrol acetate.

Symptoms and laboratory evidence of adrenal suppression developed in 2 children with the human immunodeficiency virus after megestrol acetate (MA) therapy was discontinued; both required transient glucocorticoid replacement therapy. High-dose corticotropin stimulation testing performed on children with the human immunodeficiency virus treated or not treated with MA showed that baseline and post-corticotropin cortisol levels were extremely low in 7 of 10 treated patients and normal in 10 of 10 members of a control group (P <.01). MA may suppress adrenal function, and replacement glucocorticoids may prevent or relieve associated symptoms at times of severe stress or on discontinuation of MA therapy.

Are the Duke criteria superior to the Beth Israel criteria for the diagnosis of infective endocarditis in children?

Accurate diagnosis of infective endocarditis may be difficult. The Beth Israel criteria and the newer Duke criteria assign probability to the diagnosis of infective endocarditis on the basis of the presence of common features and manifestations. We reviewed 111 cases of pediatric infective endocarditis diagnosed and treated over 19 years. Each case was classified by the two criteria, and the results were compared. Of 111 cases, 73 (66%) and 18 (16%) were classified as definite by the Duke criteria and the Beth Israel criteria, respectively. No cases were rejected by the Duke criteria, while 21 (19%) of 111 were rejected by the Beth Israel criteria. In 18 pathologically proven cases, reanalysis without pathological data showed that the Duke criteria had significantly greater sensitivity (83%) than the Beth Israel criteria (67%) (P < .03). Echocardiographic evidence was required in 22 cases for definite classification by the Duke criteria; none were rejected, however, when echocardiographic findings were ignored. Our results suggest that the Duke criteria are superior to the Beth Israel criteria for the diagnosis of pediatric infective endocarditis.

Benign and malignant smooth muscle tumors containing Epstein-Barr virus in children with AIDS.

Smooth muscle tumors (leiomyosarcomas) are the second most prevalent malignancy of children with the acquired immunodeficiency syndrome (AIDS). We have investigated the tumors, plasma, and peripheral white blood cells of eight children with AIDS with smooth muscle tumors for evidence of tumor association with human immunodeficiency virus (HIV) and Epstein-Barr virus (EBV). Very low levels of HIV were found in the tumors of the AIDS patients, probably resulting from blood-borne carriage of virus. These smooth muscle tumors had very high quantities of EBV in all the tumor cells by in situ hybridization, with an average of 4.5 EBV genomes per cell by quantitative polymerase chain reaction amplification. Increased amounts of EBV were found in the peripheral blood cells of two AIDS patients before the time of tumor diagnosis. EBV clonality studies demonstrated different monoclonal EBV infection of two separate colonic tumors from one patient, and dual or mixed monoclonal EBV infection in another patient. The muscle cells of leiomyomas and leiomyosarcomas of patients with AIDS demonstrated prominent staining with antibodies to the EBV receptor. The uniform distribution and striking amount of EBV in the tumor cells demonstrates that EBV is capable of infecting smooth muscle cells and that these cells support EBV replication. Clonal EBV proliferation suggests that EBV infection occurs at an early stage of tumor development. These findings indicate that EBV has a causal role in the oncogenesis of leiomyosarcomas of patients with AIDS.

The spectrum of mucosa-associated lymphoid tissue lesions in pediatric patients infected with HIV: A clinicopathologic study of six cases.

Mucosa-associated lymphoid tissue (MALT) lesions in nonimmunocompromised individuals include reactive lymphoid proliferations and both low- and high-grade lymphoid neoplasms. These lesions occur at extranodal mucosal sites, such as the gastrointestinal tract, bronchus, salivary gland, and other locations. The spectrum of MALT lesions in children with HIV infection had not been previously described. In this study, six cases that demonstrated the spectrum of MALT lesions in pediatric patients, aged 28 months to 23 years, who had HIV infection were described. Half the patients acquired the infection perinatally, and half acquired it by transfusion. Mucosal sites of involvement included the salivary gland (4 patients), bronchiolar mucosa (2 patients), and oropharyngeal mucosa (1 patient). One patient had lesions in lung and oropharynx sequentially; all others had involvement of solitary sites. The histologic diagnoses included myoepithelial sialadenitis (MESA), MESA with low-grade MALT lymphoma, typical low-grade MALT lymphoma, diffuse large cell lymphoma (DLCL), and atypical pulmonary lymphoid hyperplasia and lymphoid interstitial pneumonitis complex. The two cases of high-grade DLCL were confined to mucosal sites (tonsil and parotid); in one of these patients, a previous biopsy specimen showed a MALT lesion with low-grade features. In two cases, quantitation of the Epstein-Barr virus (EBV) genome by the polymerase chain reaction showed a very high copy number in peripheral blood mononuclear cells but a low copy number in the MALT lesion, which suggested that MALT lesions may not be directly associated with EBV infection. Two patients who had high-grade tumors (DLCL) were successfully treated with chemotherapy and radiation therapy. The remaining patients, all of whom had low-grade MALT lesions, received either corticosteroids or alpha-interferon or no specific therapy; in all patients, the lesions followed an indolent clinical course. Clinicians and pathologists should be alert to the possibility that MALT lesions, including MALT lymphomas, may be present in children who have AIDS.

Megestrol acetate treatment of growth failure in children infected with human immunodeficiency virus.

OBJECTIVE: To evaluate the effect of megestrol acetate on weight gain and linear growth in human immunodeficiency virus-infected children with growth failure. METHODS: All human immunodeficiency virus-infected children with growth failure treated with megestrol acetate at our institution were evaluated retrospectively. Weight, height, and weight:height ratio were documented from 6 months before initiation of megestrol acetate until 6 months after treatment was discontinued. Measurements were corrected for age and sex by conversion to z-scores. Incremental growth was determined before, during, and after treatment. The potential effects of CD4+ T-lymphocyte count and percentage, antiretroviral therapy, and intercurrent illnesses on growth were evaluated. RESULTS: Nineteen patients were treated with a total of 27 courses of megestrol acetate. The median duration of therapy was 7 months (range, 3 to 11 months), and the median megestrol acetate dose was 7.91 mg/kg/day (range, 4.06 to 8.56 mg/kg/day). From 6 months and 3 months before treatment to the onset of therapy, median changes in weight z-scores were -.27 and -.15, respectively. During megestrol acetate treatment, median changes in weight z-scores were +.29 after 1 month of therapy, +.40 after 3 months, and +.57 after 6 months. After megestrol acetate therapy was discontinued, poor weight gain and weight loss resumed. Median 6-month growth velocities for weight were less than the 10th percentile before megestrol acetate, greater than the 97th percentile during treatment, and less than the 3rd percentile after treatment was discontinued. Megestrol acetate therapy was not associated with changes in linear growth. Antiretroviral therapy, CD4+ T-lymphocyte count or percentage, or intercurrent illnesses were not associated with statistically significant differences in response to megestrol acetate therapy. CONCLUSIONS: Megestrol acetate treatment of growth failure in pediatric human immunodeficiency virus disease is associated with weight gain, without affecting linear growth.

Failure to thrive in HIV-infected children: incidence, prevalence, and clinical correlates.

"Failure to thrive" is a frequent component of the acquired immunodeficiency syndrome (AIDS) in childhood. This retrospective study was conducted to document the incidence, prevalence, and clinical correlates of "failure to thrive" in a cohort of 97 HIV-infected children seen at a large urban teaching hospital over an 8-year period. "Failure to thrive" was defined as percent of body weight for height age < or = 90%. The cumulative incidence of failure to thrive in our cohort was 37/97 (38%), with a current prevalence of 13/97 (14%). When 33 patients with severe symptomatic HIV infection [Centers for Disease Control (CDC) class C] were analyzed separately, the cumulative incidence rose to 22/33 (67%) and current prevalence to 9/33 (27%). CDC class C correlated with failure to thrive (p < 0.001), as did absolute CD4 cell count more than two standard deviations below the mean for age (p < 0.001). Neither the mode of acquisition of HIV infection nor the presence of HIV antigenemia correlated with failure to thrive. During follow-up, 34/37 patients with failure to thrive gained weight; in 17 this was associated with specific nutritional therapy. Treatment with zidovudine (AZT) was also associated with a significant weight gain (p < 0.01). The incidence and prevalence of failure to thrive in our cohort are lower than in previous reports. We conclude that enrollment of HIV-infected children in a comprehensive clinic providing nutritional evaluation, supplemental feeding, treatment of opportunistic infections, antiretroviral medications, and psychosocial support will likely continue to reduce the incidence and prevalence of "failure to thrive."

Phase I evaluation of zalcitabine administered to human immunodeficiency virus-infected children.

The safety, tolerability, and pharmacokinetics of zalcitabine (ddC) in a single oral dose (0.02 mg/kg) was evaluated in 23 mildly symptomatic human immunodeficiency virus-infected children (mean age, 4.2 years). After administration of ddC, blood samples were obtained at 0.5, 1, 1.5, 2, 4, 6, and 8 h for analysis. The drug was well tolerated and no side effects were noted. Plasma ddC levels were determined by ion spray liquid chromatography/tandem mass spectrometry. ddC was rapidly absorbed, with a mean maximum plasma concentration of 9.3 ng/mL (range, 3.2-14.1) attained within a mean of 1 h (range, 0.5-2.0). Mean elimination half-life was 1.4 h (range, 1.0-3.5), mean area under the plasma concentration-time curve was 25 ng.h/mL (range, 11-37), and mean total body clearance was 14.6 mL/min/kg (range, 8.9-30.6). Plasma concentrations were lower and the half-life shorter in these children than in adults given comparable doses, suggesting that ddC may be cleared more rapidly in children than adults.

Pediatric AIDS.

An estimated 1 million children worldwide have AIDS. Pediatricians should be aware of this disease and its many facets. This article provides information on the etiology and pathogenesis of AIDS in children, as well as its manifestations on the body. Prevention and clinical management are also reviewed.

Association of Epstein-Barr virus with leiomyosarcomas in young people with AIDS.

BACKGROUND: Children with the acquired immunodeficiency syndrome (AIDS) have an unusually high incidence of smooth-muscle tumors (leiomyomas and leiomyosarcomas) in addition to malignant lymphomas. We tested the hypothesis that the smooth-muscle tumors in these children are associated with the Epstein-Barr virus (EBV). METHODS: Tissue specimens of five leiomyosarcomas and two leiomyomas from six children with AIDS were studied for evidence of the human immunodeficiency virus (HIV) and EBV by in situ hybridization and quantitative polymerase chain reaction (PCR). Comparison specimens included samples of leiomyosarcoma and leiomyoma from HIV-negative children. EBV clonality of leiomyosarcomas was determined by Southern blot analysis with oligonucleotide probes for EBV terminal-repeat fragments. Tumor specimens were tested by immunoperoxidase staining for infiltration by B lymphocytes and expression of the EBV receptor. Serologic testing for EBV was performed. RESULTS: In situ hybridization showed EBV genomes in all muscle cells of the five leiomyosarcomas and the two leiomyomas from the six HIV-infected children. Quantitative PCR demonstrated strikingly high levels of EBV in tumor tissue, with as many as 4.3 genome copies per cell. Two colonic leiomyosarcomas obtained from different sites at different times from one patient contained different episomal EBV clones, signifying the presence of distinct monoclonal EBV-related tumors. We found biclonal EBV infection in the leiomyosarcoma of another patient. No EBV was detected in normal muscle or tumor specimens from HIV-negative patients. Immunostaining for the EBV receptor was strongly positive in six of the seven leiomyomas and leiomyosarcomas from the patients with AIDS. CONCLUSIONS: EBV can infect smooth-muscle cells, at least in patients with AIDS, and it may contribute to the pathogenesis of leiomyomas and leiomyosarcomas in children with AIDS. EBV seems to play no part in smooth-muscle tumors in HIV-negative children.

Serologic response to standard inactivated influenza vaccine in human immunodeficiency virus-infected children.

We compared the serologic response of 46 human immunodeficiency virus (HIV)-infected children and adolescents and 61 age-matched controls to standard trivalent inactivated influenza vaccine (A/Taiwan (H1N1), A/Shanghai (H3N2), B/Yamagata). Children were immunized according to the package insert recommendations before the 1990 to 1991 influenza season. Serum antibody titers to influenza A were determined before and 1 month after each vaccination and compared for study and control subjects. Serologic responses of HIV-infected participants were correlated with absolute CD4 counts and stage of HIV disease. Regardless of age or HIV status, all groups responded with significant increases in antibody to the influenza A strains (range, 2.1-fold to 11.8-fold), with the exception that antibody to H3N2 rose only 1.5-fold (P = 0.058) among HIV-positive subjects > or = 9 years old. Pre- and postimmunization antibody titers were significantly higher for controls than for HIV-positive subjects. There was no correlation between serologic responses and CD4 counts among HIV-infected subjects, but those with Centers for Disease Control and Prevention-defined acquired immunodeficiency syndrome responded significantly less well to vaccine. We conclude that HIV-infected children and adolescents produce significant antibody rises after inactivated influenza A vaccination but that their absolute antibody concentrations are lower than those seen in age-matched controls.