PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-19 (19)
 

Clipboard (0)
None

Select a Filter Below

Journals
more »
Year of Publication
more »
author:("kolstad, Paul")
1.  Complete Genome Sequence of Coxsackievirus B1 Isolated during Case Outbreaks in 2007 in the United States 
Genome Announcements  2014;2(4):e00574-14.
In 2007, clusters of severe coxsackievirus B1 (CVB1) infection occurred across the United States, and CVB1 became the most commonly reported enterovirus. The complete genome sequence of CVB1 isolated from an infant (CVB1-Chi07) was examined and found to be divergent from the Conn5 reference strain, with 80% and 96% similarities at the nucleotide and amino acid levels, respectively.
doi:10.1128/genomeA.00574-14
PMCID: PMC4110215  PMID: 25059857
2.  Timing and Predictors of Fever and Infection after Craniotomy for Epilepsy in Children 
Background
Fevers and leukocytosis after pediatric craniotomy trigger diagnostic evaluation and antimicrobial therapy for possible brain infection. This study determined the incidence and predictors of infection in infants and children undergoing epilepsy neurosurgery.
Methods
We reviewed the postoperative course of 100 consecutive surgeries for pediatric epilepsy, comparing those with and without infections for clinical variables and daily maximum temperatures, blood WBC and differential, and cerebrospinal fluid (CSF) studies.
Results
Infections were the most common adverse events following these surgeries. Four patients (4%) had CSF infections and 12 had non-CSF infections (including one with distinct CSF and bloodstream infections). Most (88%) infections occurred before postoperative day 12 and were associated with larger resections involving ventriculostomies. Fevers (T ≥38.5°C) were observed in the first 12-days postsurgery in 43 % of cases, and were associated with patients undergoing hemispherectomy and multilobar resections. Fevers in the first three days postsurgery identified infections with 73% sensitivity, 69% specificity, and 70% accuracy; two (13%) patients with infections never developed fevers. Peripheral blood WBC >15,000 was found in 49% of patients and 5 cases of infections never had elevated WBC counts. WBC differential, CSF protein, RBC, WBC, and RBC/WBC ratios were poor predictors of infections. Longer hospital stays were associated with infections and hemispherectomy and multilobar resections. Patients with and without infections were equally likely to be seizure free after surgery.
Conclusions
Fevers and elevated blood WBC counts were common after pediatric epilepsy surgery, but CSF infections were uncommon. Positive cultures and other confirmatory microbiologic tests should drive changes in antimicrobial therapy after surgery.
doi:10.1097/INF.0b013e318287b408
PMCID: PMC3717398  PMID: 23348815
Seizure; neurosurgery; ventriculostomy; CSF; infection
3.  Myocarditis, Disseminated Infection, and Early Viral Persistence Following Experimental Coxsackievirus B Infection of Cynomolgus Monkeys 
PLoS ONE  2013;8(9):e74569.
Coxsackievirus B (CVB) infection is a common cause of acute viral myocarditis. The clinical presentation of myocarditis caused by this enterovirus is highly variable, ranging from mildly symptoms to complete hemodynamic collapse. These variations in initial symptoms and in the immediate and long term outcomes of this disease have impeded development of effective treatment strategies. Nine cynomolgus monkeys were inoculated with myocarditic strains of CVB. Virological studies performed up to 28 days post-inoculation demonstrated the development of neutralizing antibody in all animals, and the presence of CVB in plasma. High dose intravenous inoculation (n = 2) resulted in severe disseminated disease, while low dose intravenous (n = 6) or oral infection (1 animal) resulted in clinically unapparent infection. Transient, minor, echocardiographic abnormalities were noted in several animals, but no animals displayed signs of significant acute cardiac failure. Although viremia rapidly resolved, signs of myocardial inflammation and injury were observed in all animals at the time of necropsy, and CVB was detected in postmortem myocardial specimens up to 28 days PI. This non-human primate system replicates many features of illness in acute coxsackievirus myocarditis and demonstrates that myocardial involvement may be common in enteroviral infection; it may provide a model system for testing of treatment strategies for enteroviral infections and acute coxsackievirus myocarditis.
doi:10.1371/journal.pone.0074569
PMCID: PMC3767629  PMID: 24040287
4.  Monitoring of HIV Type 1 DNA Load and Drug Resistance in Peripheral Blood Mononuclear Cells During Suppressive Antiretroviral Therapy Does Not Predict Virologic Failure 
Abstract
Our objective was to determine whether monitoring HIV-1 DNA concentration or new resistance mutations in peripheral blood mononuclear cells (PBMCs) during effective antiretroviral therapy (ART) predicts virologic failure. A retrospective analysis used blood specimens and clinical data from three nevirapine containing arms of a four-arm, open-label, randomized trial comparing ART regimens in HIV-1-infected children who had failed mono- or dual-nucleoside therapy. Sensitive assays compared cell-associated HIV-1 DNA concentrations and nevirapine (NVP) and lamivudine (3TC) resistance mutations in children with plasma HIV-1 RNA <400 copies(c)/ml who did or did not experience subsequent virologic failure. Forty-six children were analyzed through the last available follow-up specimen, collected at 48 (n=16) or 96 (n=30) weeks of ART. Thirty-five (76%) had sustained viral suppression and 11 (24%) had plasma viral rebound to ≥400 c/ml (virologic failure detected at a median of 36 weeks). HIV-1 DNA levels at baseline, 24, 48, and 96 weeks of ART were similar in children who did vs. did not experience virologic failure (p=0.82). HIV-1 DNA levels did not increase prior to viral rebound. NVP resistance mutations were detected in 91% of subjects in the failure group vs. 3% in the suppressed group (p <0.0001). Among nine evaluable children, NVP mutations were first detected prior to virologic failure in two (22%), at viral rebound in five (56%), and after failure in two (22%) children. HIV-1 DNA concentrations did not predict virologic failure in this cohort. New drug resistance mutations were detected in the PBMCs of a minority of virologically suppressed children who subsequently failed ART.
doi:10.1089/aid.2011.0039
PMCID: PMC3399556  PMID: 22081867
5.  Functional Analysis of HIV Type 1 Nef Gene Variants from Adolescent and Adult Survivors of Perinatal Infection 
Abstract
Throughout the world, infants and children with HIV-1 infection are increasingly surviving into adolescence and adulthood. As HIV Nef is an important determinant of the pathogenic potential of the virus, we examined nef alleles in a cohort of extreme long-term survivors of HIV infection (average age of 16.6 years) to determine if Nef defects might have contributed to patient survival. HIV nef gene sequences were amplified for phylogenetic analysis from 15 adolescents and adults infected by mother-to-child transmission (n=10) or by blood transfusion (n=5). Functional analysis was performed by inserting patient-derived nef sequences into an HIV-derived vector that permits simultaneous evaluation of the impact of the Nef protein on MHC-I and CD4 cell surface expression. We found evidence of extensive nef gene diversity, including changes in known functional domains involved in the downregulation of cell surface MHC-I and CD4. Only 3 of 15 individuals (20%) had nef alleles with a loss of the ability to downregulate either CD4 or MHC-I. Survival into adulthood with HIV infection acquired in infancy is not uniformly linked to loss of function in nef. The Nef protein remains a potential target for immunization or pharmacologic intervention.
doi:10.1089/aid.2011.0172
PMCID: PMC3332374  PMID: 21861776
6.  Fluoxetine Is a Potent Inhibitor of Coxsackievirus Replication 
No antiviral drugs currently exist for the treatment of enterovirus infections, which are often severe and potentially life threatening. Molecular screening of small molecule libraries identified fluoxetine, a selective serotonin reuptake inhibitor, as a potent inhibitor of coxsackievirus replication. Fluoxetine did not interfere with either viral entry or translation of the viral genome. Instead, fluoxetine and its metabolite norfluoxetine markedly reduced the synthesis of viral RNA and protein. In view of its favorable pharmacokinetics and safety profile, fluoxetine warrants additional study as a potential antiviral agent for enterovirus infections.
doi:10.1128/AAC.00983-12
PMCID: PMC3421851  PMID: 22751539
8.  New Delhi Metallo-β-Lactamase (NDM-1)-Producing Klebsiella pneumoniae: Case Report and Laboratory Detection Strategies▿ 
Journal of Clinical Microbiology  2011;49(4):1667-1670.
The spread of antimicrobial resistance among Enterobacteriaceae is a significant clinical threat. We report the first case of an Enterobacteriaceae strain harboring the NDM-1 metallo-β-lactamase in a pediatric patient in the United States. We describe strategies for the detection of this novel resistance mechanism encountered in an isolate of Klebsiella pneumoniae.
doi:10.1128/JCM.00183-11
PMCID: PMC3122842  PMID: 21325558
9.  Youth-Specific Considerations in the Development of PrEP, Microbicide and Vaccine Research Trials 
Preventing HIV infection in adolescents and young adults will require a multimodal, targeted approach including individual-directed behavioral risk reduction, community-level structural change, and biomedical interventions to prevent sexual transmission. Trials testing biomedical interventions to prevent HIV transmission will require special attention in this population due to the unique psychosocial as well as physiologic characteristics that differentiate them from older populations. For example, microbicide research will need to consider acceptability, dosing requirements, and co-infection rates that are unique to this population. Pre-exposure prophylaxis studies also will need to consider potential unique psychosocial issues such as sexual disinhibition and acceptability as well as unique pharmacokinetic parameters of antiretroviral agents. Vaccine trials also face unique issues with this population, including attitudes towards vaccines, risks related to false-positive HIV tests related to vaccine, and different immune responses based on more robust immunity. In this paper, we will discuss issues around implementing each of these biomedical prevention modalities in trials among adolescents and young adults to help to guide future successful research targeting this population.
doi:10.1097/QAI.0b013e3181e3a922
PMCID: PMC2912697  PMID: 20571421
Adolescents; youth; biomedical HIV prevention; vaccines; PrEP; microbicides
10.  Short Communication: Enhanced CD8+ T Cell Apoptosis in HIV-Infected Adolescents with Virologic Failure on Protease Inhibitor-Based Therapy 
Abstract
In this study, we investigated the possibility of differential effects of protease inhibitor (PI)-containing (PI+) and PI-sparing (PI−) antiretroviral therapies (ART) on CD8+ T cell apoptosis. We retrospectively analyzed both PD-1 expression and CD8+ T cell apoptosis in a cross-sectional study of HIV-positive adolescents and young adults (mean age = 17.4 years), with perinatally or behaviorally acquired HIV infection. Fifty-one specimens of cryopreserved peripheral blood mononuclear cells (PBMCs) were analyzed using 7-color flow cytometry: 20 from patients receiving PI+ ART, 14 from PI− ART, and 17 from the untreated. The results showed that percentages of PD-1+ CD8+ T cells were strongly correlated with plasma viral loads regardless of treatment (p = 0.0001). The percentage of PD-1+ CD8+ T cells was also positively associated with percentages of Annexin V+ CD8+ T cells (p = 0.04) in the PI+-treated group. The fraction of apoptotic (Annexin V+) CD8+ T cells was associated with viral load in the patients receiving ART that contained one or more protease inhibitors (p = 0.029), but not in the PI− or untreated groups. In summary, we found a direct correlation between PD-1 expression on CD8+ T cells and HIV levels that was not affected by types of medications used in the ART of those adolescents, suggesting that virological success is necessary for PD-1 downregulation. CD8+ T cell apoptosis was linked to high levels of PD-1 expression and HIV viremia. However, there was a higher degree of apoptosis among viremic patients receiving PI therapy, suggesting an immunologically adverse effect of continuing PI+ therapy after virological failure.
doi:10.1089/aid.2009.0112
PMCID: PMC2932552  PMID: 20507209
11.  Jaundice in a neonate with congenital diaphragmatic hernia 
Paediatrics & Child Health  2009;14(6):389-392.
A six-week-old boy presented to the emergency department with worsening jaundice. His medical history included congenital diaphragmatic hernia repaired shortly after birth. Significant jaundice, unresponsive to phototherapy, was noted on the eighth day of life. His total bilirubin level decreased when he was advanced to full oral feeds. However, on the 23rd day of life, the patient’s conjugated bilirubin level had tripled. This was attributed to total parenteral nutrition, and the patient was discharged home. Over the next month, his jaundice worsened. The patient was readmitted and ultimately diagnosed with cytomegalovirus (CMV) hepatitis. After treatment with ganciclovir, his hepatitis completely resolved. CMV infection is a common cause of neonatal hepatitis and congenital malformation. Prolonged neonatal jaundice that does not improve with transitioning from total parenteral nutrition to oral feeds warrants further evaluation. Simple laboratory investigation can avoid unnecessary and potentially harmful medical and surgical interventions. Early treatment of neonatal CMV infection reduces the risk of long-term neurological and hepatic complications.
PMCID: PMC2735383  PMID: 20592976
Cholestasis; Congenital diaphragmatic hernia; Cytomegalovirus; Neonatal hepatitis; Neonatal jaundice
12.  Packaging Limits and Stability of HIV-1 Sequences in a Coxsackievirus B Vector 
Vaccine  2009;27(30):3992-4000.
Enteroviruses elicit protective mucosal immune responses that could be harnessed as part of a strategy to prevent sexual transmission of the human immunodeficiency virus-1 (HIV-1). We report the construction of replication competent recombinant vectors of coxsackievirus B3 (CVB3) that express one or more portions of the HIV-1 Gag protein. Vectors containing the capsid domain of Gag were initially genetically unstable with protein expression lost after brief passage in tissue culture. Codon modification to increase the G/C content of the HIV-1 capsid sequence resulted in enhanced genetic stability of CVB3 vectors during in vitro passage. Cells infected with a vector expressing the matrix (MA) subunit of the HIV-1 Gag protein were susceptible to lysis by CD8 T cell clones specific for the SL9 epitope found within MA. These studies suggest that CVB3 vectors may be useful as vaccine vector candidates, if hurdles in class I antigen presentation and stability can be overcome.
doi:10.1016/j.vaccine.2009.04.035
PMCID: PMC2745320  PMID: 19389440
HIV-1; Vaccine; Coxsackievirus B3
13.  In Vivo Validation of a Bioinformatics Based Tool to Identify Reduced Replication Capacity in HIV-1 
Although antiretroviral drug resistance is common in treated HIV infected individuals, it is not a consistent indicator of HIV morbidity and mortality. To the contrary, HIV resistance-associated mutations may lead to changes in viral fitness that are beneficial to infected individuals. Using a bioinformatics-based model to assess the effects of numerous drug resistance mutations, we determined that the D30N mutation in HIV-1 protease had the largest decrease in replication capacity among known protease resistance mutations. To test this in silico result in an in vivo environment, we constructed several drug-resistant mutant HIV-1 strains and compared their relative fitness utilizing the SCID-hu mouse model. We found HIV-1 containing the D30N mutation had a significant defect in vivo, showing impaired replication kinetics and a decreased ability to deplete CD4+ thymocytes, compared to the wild-type or virus without the D30N mutation. In comparison, virus containing the M184V mutation in reverse transcriptase, which shows decreased replication capacity in vitro, did not have an effect on viral fitness in vivo. Thus, in this study we have verified an in silico bioinformatics result with a biological assessment to identify a unique mutation in HIV-1 that has a significant fitness defect in vivo.
doi:10.2174/1874431101004010225
PMCID: PMC3097495  PMID: 21603285
HIV-1; replication capacity; bioinformatics; Bayesian; variable selection; exchangeable on subsets; prior model selection; in vivo validation.
14.  Enfuvirtide antiretroviral therapy in HIV-1 infection 
It has been over 25 years since the first diagnosis of what would be known as AIDS. Although great strides in anti-HIV therapeutics have been made, there is still a great need for antiretrovirals that are effective against drug-resistant HIV. Enfuvirtide (ENF) is the first of a new class of fusion inhibitors to be approved by the US Food and Drug Administration for use in combination with other antiretroviral agents among HIV-1 infected patients with previous treatment experience. The inclusion of enfuvirtide in an optimized antiretroviral background regimen for the treatment of HIV-1 infected (treatment-experienced) patients followed the success of two critical clinical trials (TORO: T20 vs Optimized Regimen Only I and II). Even though injection-site reactions persisted in these trials, improved virological and immunological responses were observed among patients. Challenges associated with ENF treatment include the high cost of the drug, injection-site reactions, determining the optimal time to initiate treatment, and the potential for the selection of drug resistant mutants and viral evolution. ENF is a promising novel treatment for HIV infected individuals whose choices for effective treatment are limited by previous treatment and resistance. Understanding the implications of viral fitness and evolution in the presence of ENF treatment is crucial in determining effective and safe treatment regimens, particularly among treatment-experienced patients.
PMCID: PMC2504070  PMID: 18728846
enfuvirtide; HIV; salvage therapy; drug resistance; gp41; evolution
15.  Genetic and Stochastic Influences on the Interaction of Human Immunodeficiency Virus Type 1 and Cytotoxic T Lymphocytes in Identical Twins†  
Journal of Virology  2005;79(24):15368-15375.
Human immunodeficiency virus type 1 (HIV-1) evolves in vivo under selective pressure from CD8+ T-lymphocyte (CTL) responses, which are in turn determined by host and viral genetic factors, such as restricting major histocompatibility complex molecules and the available viral epitope sequences. However, CTL are derived stochastically through the random gene rearrangements to produce T-cell receptors (TCR), and the relative impact of genetic versus stochastic processes on CTL targeting of HIV and immune-driven viral evolution is unclear. Here we evaluate identical twins infected with HIV-1 as neonates from a common blood transfusion, with subsequently similar environmental exposures, thereby allowing controlled comparisons of CTL targeting and viral evolution. Seventeen years after infection, their CTL targeting of HIV-1 was remarkably similar. In contrast, their overall TCR profiles were highly dissimilar, and a dominant epitope was recognized by distinctly different TCR in each twin. Furthermore, their viral epitopes had diverged, and there was ongoing viral phylogenetic divergence between the twins between 12 and 17 years after infection. These results indicate that while CTL targeting is predominately genetically determined, stochastic influences render the interaction of HIV-1 and host immunity, and therefore viral escape and CTL efficacy, unpredictable.
doi:10.1128/JVI.79.24.15368-15375.2005
PMCID: PMC1316030  PMID: 16306608
16.  Assessment of Thymic Activity in Human Immunodeficiency Virus-Negative and -Positive Adolescents by Real-Time PCR Quantitation of T-Cell Receptor Rearrangement Excision Circles 
Circular DNA molecules known as T-cell receptor rearrangement excision circles (TREC) arise during T-cell development and are present in cells that have recently emigrated from the thymus. In cross-sectional studies, the number of peripheral blood lymphocytes bearing TREC decreases with age, consistent with an anatomically demonstrated loss of thymic epithelial tissue. TREC numbers increase following hematopoietic stem cell transplantation and during therapy for human immunodeficiency virus (HIV) infection. Quantitation of TREC has therefore been proposed as a parameter of thymic activity. In this study, we used real-time PCR to quantify TREC in peripheral blood samples obtained longitudinally from HIV-seronegative adolescents. TREC values in peripheral blood T cells were very stable throughout adolescence, once thought to be a time of rapid involution of the thymus. In addition, in a cross-sectional analysis, we examined TREC values in a cohort of HIV-positive adolescents and found evidence of ongoing thymopoiesis in perinatally infected individuals, despite lifelong infection. These data demonstrate the utility of TREC assessment in adolescents and that HIV infection does not uniformly result in accelerated thymic involution in childhood.
doi:10.1128/CDLI.10.2.323-328.2003
PMCID: PMC150534  PMID: 12626462
17.  Performance of the Applied Biosystems ViroSeq Human Immunodeficiency Virus Type 1 (HIV-1) Genotyping System for Sequence-Based Analysis of HIV-1 in Pediatric Plasma Samples 
Journal of Clinical Microbiology  2001;39(4):1254-1257.
The ViroSeq HIV-1 Genotyping System is a commercially available, integrated sequence-based system for analysis of human immunodeficiency virus type 1 (HIV-1) drug resistance. We evaluated the performance of this system by analyzing HIV-1 in pediatric plasma samples. Plasma samples from children 4 months to 17 years of age were obtained from a clinical trial protocol (PACTG 377). Children in PACTG 377 were randomized to four treatment arms, including different combinations of antiretroviral drugs. HIV-1 genotyping was performed using samples collected prior to antiretroviral therapy (baseline) and at the time of virologic failure. Performance of the genotyping system was compared in three university laboratories. A total of 196 samples were analyzed, including 135 baseline and 61 failure samples. Plasma volumes ranged from 0.05 to 0.5 ml, and viral loads ranged from 1,084 to 3,484,991 copies/ml. PCR products suitable for sequencing were obtained for 192 of the 196 samples. Complete sequences for protease and reverse transcriptase were obtained for all of these 192 samples. For 180 samples, data were obtained from both DNA strands for the entire region analyzed. There was no evidence of sample cross-contamination based on phylogenetic analysis of HIV-1 sequences. Performance of the genotyping system was similar in three laboratories. This genotyping system performs well for analysis of HIV-1 in pediatric plasma samples, including those with low volume and low viral load. The availability of this system should facilitate studies of HIV-1 drug resistance.
doi:10.1128/JCM.39.4.1254-1257.2001
PMCID: PMC87920  PMID: 11283037
18.  Cryoelectron Microscopic Examination of Human Immunodeficiency Virus Type 1 Virions with Mutations in the Cyclophilin A Binding Loop 
Journal of Virology  1998;72(5):4403-4407.
The human immunodeficiency virus type 1 capsid protein contains a conserved P217X4PX2PX5P231 motif. Mutation at Pro-222 decreases virion incorporation of cyclophilin A, while mutation at Pro-231 abolishes infectivity. Although viral RNA incorporation and protease cleavage of the Gag precursor were not affected by these mutations, cryoelectron microscopy revealed a loss of virion maturation in P231A particles.
PMCID: PMC109671  PMID: 9557731
19.  Cells with High Cyclophilin A Content Support Replication of Human Immunodeficiency Virus Type 1 Gag Mutants with Decreased Ability To Incorporate Cyclophilin A 
Journal of Virology  1998;72(1):303-308.
Gag polyprotein-mediated incorporation of cellular cyclophilin A (CyPA) into virions is essential for the formation of infectious human immunodeficiency virus type 1 (HIV-1) virions. Either a point mutation in Gag (P222A) or drugs which bind CyPA decrease virion incorporation of CyPA and interfere with HIV-1 replication. We have found that lymphoid cells varied greatly in their CyPA content and that cells with high CyPA content supported the replication of P222A HIV-1 Gag mutants. These experiments demonstrated that a higher cellular CyPA content of some cells was able to compensate for the decreased binding affinity of P222A mutant Gag for CyPA, allowing virus replication to occur.
PMCID: PMC109377  PMID: 9420228

Results 1-19 (19)