Associations of P2RX7 Functional Diplotypes with Localized Aggressive Periodontitis

AIM

The purpose of this study was to test for the role of the P2X7 receptor in localized aggressive periodontitis (LAP).

METHODS

Peripheral blood was obtained from 95 subjects with LAP and 76 healthy unrelated controls (HUCs). Three P2RX7 single-nucleotide polymorphisms (rs1718119, rs2230911, and rs3751143) were genotyped from these subjects, and their peripheral blood samples were stimulated with lipopolysaccharide (LPS) from Escherichia coli and tested for inflammatory markers. The 3 P2RX7 single-nucleotide polymorphisms were in found to be in perfect linkage disequilibrium, and a total of 4 haplotypes and 9 diplotypes were identified among all subjects. For both subject populations, the 9 diplotypes were grouped into 4 functional groups and tested for association with subject inflammatory response. To specifically study the effects of extrinsic activation of the P2X7 receptor in LAP, peripheral blood samples from were stimulated under 3 treatments: LPS, LPS + ATP, and LPS +ATP+ P2X7 selective inhibitor. The effects of these treatments on P2X7 receptor activity were measured through Luminex protein assay. Last, to test whether receptor stimulation was related to P2RX7 expression, relative mRNA levels of P2RX7 were quantified with real-time quantitative polymerase chain reaction.

RESULTS

Several associations between the P2RX7 diplotypes and LPS-stimulated blood chemokine/cytokine levels were found between the LAP and HUC populations (P < 0.05). P2X7 activation resulted in statistically significant differences in IL-1β and IL-12p40 concentrations for both subject populations. The relative P2RX7 mRNA levels increased significantly after addition of its inhibitor for both LAP and HUC populations.

CONCLUSIONS

This study detected an association between P2RX7 functional diplotypes and in vitro immune response of whole blood from subjects with LAP. In addition, we found that inhibition of the activated P2X7 receptor leads to increased P2RX7 mRNA levels, suggesting a feedback loop ( ClinicalTrials.gov NCT01330719).

KNOWLEDGE TRANSFER STATEMENT

The results of this study suggest that P2RX7 functional diplotypes are associated with LAP and their in vitro immune response to bacteria. Ongoing studies to uncover the mechanistic link between P2RX7 and LAP phenotypes could lead to the development of preventive approaches for susceptible subjects.

Genetic polymorphisms and periodontal disease in populations of African descent: A review

Aggressive periodontitis is a rare but rapidly progressing form of periodontal disease that usually affects otherwise systemically healthy individuals, at a young age. It usually affects first molars and incisors, which are usually lost if treatment is not properly and early rendered. Although of low prevalence, it affects individuals of African descent at a higher prevalence, and usually multiple members within the same family. Several studies have been performed in the attempt to evaluate specific single nucleotide polymorphisms (SNPs) that could be associated with this disease. To the best of our knowledge, the present article provides the first review of the literature focusing on studies that evaluated SNPs in patients of African descent with aggressive periodontitis. Several SNPs have been evaluated in different genes according to their role in the pathogenesis of the disease, with positive and negative associations (such as IL1, FCGR3B, FPR1, LTF, CYBA, GLT6D1, TLR4) with both the localized and generalized forms of aggressive periodontitis. Given the complexity of periodontitis, the difficulty in gathering large cohorts diagnosed with this rare form of disease, and the fact that candidate gene studies may only determine part of the genetic risk of a disease, the search for specific SNPs associated with aggressive periodontitis seems to be a long one, most likely to result in the combination of multiple SNPs, in multiple genes.

Versatile and precise gene-targeting strategies for functional studies in mammalian cell lines

The advent of programmable nucleases such as ZFNs, TALENs and CRISPR/Cas9 has brought the power of genetic manipulation to widely used model systems. In mammalian cells, nuclease-mediated DNA double strand break is mainly repaired through the error-prone non-homologous end-joining (NHEJ) repair pathway, eventually leading to accumulation of small deletions or insertions (indels) that can inactivate gene function. However, due to the variable size of the indels and the polyploid status of many cell lines (e.g., cancer-derived cells), obtaining a knockout usually requires lengthy screening and characterization procedures. Given the more precise type of modifications that can be introduced upon homology-directed repair (HDR), we have developed HDR-based gene-targeting strategies that greatly facilitate the process of knockout generation in cell lines. To generate reversible knockouts (R-KO), a selectable promoter-less STOP cassette is inserted in an intron, interrupting transcription. Loss-of-function can be validated by RT-qPCR and is removable, enabling subsequent restoration of gene function. A variant of the R-KO procedure can be used to introduce point mutations. To generate constitutive knockouts (C-KO), an exon is targeted, which makes use of HDR-based gene disruption together with NHEJ-induced indels on non-HDR targeted allele(s). Hence the C-KO procedure greatly facilitates simultaneous inactivation of multiple alleles. Overall these genome-editing tools offer superior precision and efficiency for functional genetic approaches. We provide detailed protocols guiding in the design of targeting vectors and in the analysis and validation of gene targeting experiments.

Neurological Symptoms, Not Signs,<br />Are Common in Early HIV Infection

Objective. To examine the cross-sectional prevalence of neurological symptoms and signs in a large cohort of human immunodeficiency virus (HIV)-seropositive men, and determine the relationship of the symptoms to disease stage, immunologic markers, and independent variables from neuropsychological (NP) testing and psychiatric interview.

METHODS

One hundred-nine controls and 386 HIV-infected volunteers enrolled in the HIV Neurobehavioral Research Center (HNRC) longitudinal study. The majority, without acquired immune deficiency syndrome (AIDS), were screened for alcohol/substance abuse; previous diagnosis of HIV-associated dementia; and HIV-unrelated developmental, neurological, medical, and neurobehavioral conditions which potentially impair cognition; and underwent a structured neurological interview and examination, standardized NP testing, and psychiatric interview as part of a more extensive battery. A large subset (N = 377) underwent lumbar puncture for cerebrospinal fluid (CFS) examination. We examined the relationship of sixteen select but independent variables, using stepwise multiple regressions, from demographic/staging, immunological, NP, and psychiatric domains to neurological symptoms in an effort to identify possible predictors of subclinical nervous systems involvement. Results. All categories of neurological symptoms were significantly more prevalent among medically asymptomatic (CDC stage A) subjects than controls, with a further rise in prevalence in those with more advanced stages of infection. The most marked rise was seen in cognitive and sensorimotor complaints. In contrast, significant findings on neurological examination were evident in only the sicker (stage C) subjects. Stage of illness, serum &beta;2-microglobulin, psychiatric indices of depressed mood or anxiety, and NP "motor" performance were the most significant independent variables associated with the presence of neurological symptoms. CSF pleocytosis was seen early (CDC stage A), and may reflect the presence of HIV in the central nervous system (CNS) at the least stages of infection. We also confirmed the value of CSF &beta;2m and neopterin as important markers of advancing disease stage. Whether they predict subclinical CNS involvement is to be determined by longitudinal observations. Conclusion. Neurological complains are common in medically asymptomatic HIV subjects whereas signs are not. The symptoms correlate with commonly determined independent measures of depression, anxiety, NP tests of fine motor speed and strength, as well as indices of disease worsening (CDC stage, serum &beta;2m).

Genetic contributions to pain: a review of findings in humans

Pain represents the major motivating factor for which individuals seek healthcare, and pain responses are characterized by substantial inter-individual differences. Increasing evidence suggests that genetic factors contribute significantly to individual differences in responses to both clinical and experimental pain. The purpose of this review article was to summarize the current literature regarding genetic contributions to pain, highlighting findings relevant to oral pain where available. A brief discussion of methodologic considerations is followed by a review of findings regarding genetic influences on clinical pain. Next, the literature examining genetic contributions to experimental pain responses is presented, emphasizing genetic associations that have been replicated in multiple cohorts. It is hoped that an enhanced understanding of genetic contributions to pain responses will ultimately improve diagnosis and treatment of clinical pain conditions.

Genetic linkage of a novel autosomal dominant restrictive cardiomyopathy locus

BACKGROUND

In recent years, non-syndromic idiopathic cardiomyopathies have increasingly been characterised as autosomal dominant conditions caused by single gene mutations. Loci have been identified for hypertrophic and dilated cardiomyopathy, and in some cases the same loci are associated with restrictive cardiomyopathy (RCM). In a kindred with RCM that we previously reported, we ruled out the known cardiomyopathy loci and other candidate genes by linkage analysis and mutation screening.

METHODS AND RESULTS

Here we report a genome-wide analysis in this family that has resulted in linkage to a region on chromosome 10.

CONCLUSIONS

There are no genes in the interval that are known to cause idiopathic cardiomyopathy, and thus this linkage represents localisation of a new RCM locus.

Nf1 haploinsufficiency augments angiogenesis

Mutations in the NF1 tumor-suppressor gene underlie neurofibromatosis type 1 (NF1), in which patients are predisposed to certain tumors such as neurofibromas and may associate with vascular disorder. Plexiform neurofibromas are slow growing benign tumors that are highly vascular and can progress to malignancy. The development of neurofibromas requires loss of both Nf1 alleles in Schwann cells destined to become neoplastic and may be exacerbated by Nf1 heterozygosity in other non-neoplastic cells. This study tested the hypothesis that Nf1 heterozygosity exaggerates angiogenesis. We found that Nf1 heterozygous mice showed increased neovascularization in both the retina and cornea in response to hypoxia and bFGF, respectively, compared to their wild-type littermates. The increase in corneal neovascularization was associated with heightened endothelial cell proliferation and migration, and increased infiltration of inflammatory cells. In addition, Nf1 heterozygous endothelial cell cultures showed an exaggerated proliferative response to angiogenic factors, particularly to bFGF. These findings support the conclusion that Nf1 heterozygosity in endothelial cells and perhaps inflammatory cells augments angiogenesis, which may promote neurofibroma formation in NF1.

Melanocortin-1 receptor gene variants affect pain and mu-opioid analgesia in mice and humans

BACKGROUND

A recent genetic study in mice and humans revealed the modulatory effect of MC1R (melanocortin-1 receptor) gene variants on kappa-opioid receptor mediated analgesia. It is unclear whether this gene affects basal pain sensitivity or the efficacy of analgesics acting at the more clinically relevant mu-opioid receptor.

OBJECTIVE

To characterise sensitivity to pain and mu-opioid analgesia in mice and humans with non-functional melanocortin-1 receptors.

METHODS

Comparisons of spontaneous mutant C57BL/6-Mc1r(e/e) mice to C57BL/6 wildtype mice, followed by a gene dosage study of pain and morphine-6-glucuronide (M6G) analgesia in humans with MC1R variants.

RESULTS

C57BL/6-Mc1r(e/e) mutant mice and human redheads--both with non-functional MC1Rs--display reduced sensitivity to noxious stimuli and increased analgesic responsiveness to the mu-opioid selective morphine metabolite, M6G. In both species the differential analgesia is likely due to pharmacodynamic factors, as plasma levels of M6G are similar across genotype.

CONCLUSIONS

Genotype at MC1R similarly affects pain sensitivity and M6G analgesia in mice and humans. These findings confirm the utility of cross species translational strategies in pharmacogenetics.

Association between β-adrenergic receptor polymorphisms and their G-protein-coupled receptors with body mass index and obesity in women: a report from the NHLBI-sponsored WISE study

OBJECTIVES

The beta-adrenergic receptor (betaAR) genes are candidate genes for obesity because of their roles in energy homeostasis and promotion of lipolysis in human adipose tissue. Objective is to determine the association between obesity and polymorphisms in genes of the beta(1)AR (ADRB1), beta(2)AR (ADRB2), beta(3)AR (ADRB3), Gs protein alpha (GNAS1), to which all three beta-receptors couple and the G protein beta3 subunit (GNB3), to which beta(3)ARs couple.

DESIGN

A case-control genetic association study.

SUBJECTS

A total of 643 black or white women enrolled in Women's Ischemia Syndrome Evaluation (WISE) study.

MEASUREMENTS

Genotypes were determined by PCR with single primer extension. Associations between genotype and body mass index (BMI), waist-to-hip ratio (WHR), waist circumference, and obesity were made.

RESULTS

Polymorphisms in the three betaAR genes, GNAS1, and GNB3 were not associated with BMI, WHR, waist circumference, or obesity. Linear and logistic regression analyses found no contribution of either genotype or haplotype with anthropometric measurements or obesity.

CONCLUSIONS

Our study suggests that among American women with suspected coronary heart disease, polymorphisms in the betaARs and their G-protein-coupled receptors do not contribute to increased BMI, WHR, waist circumference, or obesity. Given that 50% of all women die from coronary heart disease, and a higher percentage have heart disease during their lifetime, our results are likely generalizable to many American women.

Inheritance of cataract in the Bichon Frise

OBJECTIVE

To determine the mode of inheritance of cataract formation in the Bichon Frise.

MATERIALS

Thirty-six closely related Bichon Frise dogs in a pedigree of 61 dogs were examined using slit-lamp biomicroscopy and indirect ophthalmoscopy over a period of 10 years.

RESULTS

Of the 61 related dogs, 36 were examined repeatedly. Twelve cataractous dogs were diagnosed (three males and nine females). Cataractous dogs resulted from matings between unaffected parents, and when one parent was cataractous and the other parent was unaffected. Age at onset of cataract formation ranged from 18 to 160 months. Available information suggests that the cataracts are inherited as an autosomal recessive trait.

CONCLUSION

Cataracts appear inherited in the Bichon Frise as an autosomal recessive trait. Additional cataract x cataract matings are necessary to confirm the autosomal recessive heredity.

Blood lymphocyte chimerism associated with IVF and monochorionic dizygous twinning: Case report

We report on dizygotic (DZ) twins, conceived by IVF and ICSI with assisted hatching, who each had a mixture of 46,XX and 46,XY cells in blood lymphocytes. The female twin had mild genitalia abnormalities but further study revealed anatomically normal reproductive anatomy. Chromosome and fluorescence in situ hybridization studies of buccal, skin and ovarian tissue were normal, as were buccal tissue DNA studies. Fetal ultrasound and fetal membrane pathology were consistent with a monochorionic, diamniotic placenta (MCDAP). These twins thus have blood chimerism but are not chimeric in the other tissues studied. The mechanism for the chimerism could be due to either placental vascular anastamoses (after the development of the haematoblast stem cells) or due to an admixture of trophoblast cells during early blastocyst development. Such trophoblast cell admixtures would be restricted to the extraembryonic tissues so that general physical development in the fetus is normal and without somatic cell chimerism. This case in combination with others previously reported suggests that in IVF conceptions, the prevalence of blood chimerism associated with twinning, and the occurrence of DZ twinning associated with MCDAP, may be higher than previously thought.

Predictors of HIV-specific lymphocyte proliferative immune responses induced by therapeutic vaccination

We treated a cohort of 38 HIV-infected individuals with a therapeutic vaccine (REMUNE, HIV-1 Immunogen) in an open label study. We then determined whether baseline parameters, such as CD4 cell count, viral load and IgG levels, were predictive of the magnitude of the HIV-specific lymphocyte proliferative responses (LPRs). We demonstrate herein that there is a significant enhancement from baseline for both HIV and p24 antigen-stimulated LPRs after immunization. Using a responder definition of a stimulation index of >5 on at least two post-immunization time-points, 29/38 (76%) responded to HIV-1 antigen while 27/38 (71%) responded to native p24 antigen. Viral load and total IgG were negatively correlated, while CD4 cell counts were positively associated with the magnitude of the HIV antigen LPR. In a multivariable analysis, baseline CD4 was the best predictor of HIV antigen LPR post-immunization.

Bartonella henselae serostatus is not correlated with neurocognitive decline in HIV infection

Bartonella henselae has been implicated as a significant cause of HIV-associated dementia. We attempted to confirm this association by utilizing the database of the San Diego HIV Neurobehavioral Research Center, which collects longitudinal neurocognitive and laboratory data on over 500 HIV-infected participants. Utilizing an immunofluorescent assay we found that 11% of 177 subjects, half of whom had documented neurocognitive decline, were seropositive for B. henselae. There was no correlation between B. henselae seropositivity and neurocognitive decline. The role of B. henselae in HIV-associated dementia remains ambiguous.

Supravalvular aortic stenosis: genetic and molecular dissection of a complex mutation in the elastin gene

We have identified two elastin gene (ELN) mutations located in cis in two related families with supravalvular aortic stenosis (SVAS). These mutations included an in-frame duplication in exon 18 (1034-1057dup) and a single base substitution in exon 26 (1829G-->A) predicted to result in the amino acid substitution R610Q. Haplotype analysis in one of the families identified an individual with a recombination between exon 18 and 26 of the elastin gene. This individual was unaffected and carried the exon 18 insertion mutation but not 1829G-->A. Skin fibroblasts were established from this recombinant normal individual and from an affected individual carrying both of the mutations. Reverse transcription/polymerase chain reaction (RT-PCR) analysis indicated that the expression of the mutant allele was reduced to 12%-27% of the normal allele in the affected but not in the unaffected individual. RNA-blot hybridization and immunoprecipitation experiments revealed reduced steady-state elastin mRNA levels and tropoelastin synthesis in the affected individual. RT-PCR analysis of the mRNA rescued by cycloheximide treatment indicated that mutation 1829G-->A created a cryptic donor splice site within exon 26, resulting in the deletion of four nucleotides at the 3'-end of exon 26 and a frameshift in the mRNA. This frameshift mutation generated a premature termination codon in the domain encoded by exon 28, clearly resulting in nonsense-mediated decay (NMD) of this frameshift RNA product. Despite considerable variability in the molecular nature of mutations responsible for SVAS, the unifying mechanism appears to be the generation of null alleles by NMD leading to elastin haploinsufficiency.

Randomized, placebo-controlled clinical trial of oral azithromycin prophylaxis against respiratory infections in a high-risk, young adult population

Military Special Forces trainees undergo intense psychological and physical stressors that often lead to respiratory infection. During 1998-2000, 477 Navy Special Forces trainees were enrolled in a double-blind trial of oral azithromycin (1 g given weekly) plus a placebo injection, compared with benzathine penicillin G (1.2 million U) plus azithromycin placebo tablets. Among the 464 subjects with complete data, 44 developed acute respiratory infection (20 with pneumonia) during the 2 weeks of most intense training; of these subjects, 12 (27.3%) had evidence of Chlamydia pneumoniae infection and 7 (15.9%) had evidence of Mycoplasma pneumoniae infection. Trainees who received azithromycin were less likely than were trainees who received benzathine penicillin G to develop acute respiratory infection (risk ratio, 0.50; 95% confidence interval [CI], 0.28-0.92) and less likely at the end of training to report episodes of breathing difficulty (odds ratio [OR], 0.59; 95% CI, 0.34-1.01) or sore throat (OR, 0.66; 95% CI, 0.41-1.05). Compared with benzathine penicillin G prophylaxis, weekly oral azithromycin was superior in preventing respiratory infection in this population at transient high risk.

The utility of serologic testing for varicella in an adolescent population

The purpose of this study was to determine what proportion of adolescents without a history of varicella are seropositive, and if serologic testing of this adolescent subpopulation is cost-effective. We identified 122 patients with 'no' or 'unknown' histories of chicken pox from our adolescent clinic. Of these, 58 (48%) were found to be Varicella Zoster Virus (VZV) seropositive. Cost to the government for batched serologic testing of all unknowns was $682.65, while each adolescent vaccinated cost $59.60. Serologic testing prior to routine immunization of adolescents with unclear varicella histories saved $2774.15 (38% of routine immunization costs). In this population, serologic testing is more cost effective than routinely immunizing all unknowns.

The role of antibiotics in the treatment of infectious diarrhea

Infectious diarrhea is a significant cause of morbidity and mortality and a common complaint in clinical practice. Routine empirical use of antibiotics for infectious diarrhea should be avoided because of the self-limited nature of most cases, the cost of antibiotics, and the potential to worsen the already significant problem of antibiotic resistance of enteric pathogens. For patients with severe invasive or prolonged diarrhea or who are at high risk of complications, such as the elderly, diabetics, cirrhotics, and immunocompromised patients, empirical treatment with a quinolone antibiotic for 3 to 5 days can be considered. Antibiotic treatment can be highly effective for Shigella, ETEC, and V. cholerae infections, and metronidazole is indicated for C. difficile colitis. The impact of antibiotics for other specific pathogens is modest, and antibiotic therapy should be reserved for the same group of patients who would be considered for empirical treatment. The most significant problem in the antibiotic treatment of infectious diarrhea is the progressive increase in resistance among enteric pathogens; only the prudent use of antimicrobials in all areas of daily practice can limit or delay the impact of this serious problem.

Symptomatic HIV seroconverting illness is associated with more rapid neurological impairment

OBJECTIVES

To establish whether symptomatic seroconverting illness in HIV infected people is associated with more rapid development of neurological impairment.

METHODS

166 HIV infected subjects with a known date of HIV infection enrolled in a longitudinal study of neurocognitive function were stratified by whether or not they had experienced a symptomatic serconverting illness.

RESULTS

29 of 166 (17.5%) dated HIV seroconverters had a history of symptomatic seroconverting illness. Though baseline neurocognitive function was similar, subjects with a symptomatic seroconverting illness developed clinical neurocognitive impairment significantly more rapidly than their asymptomatic counterparts in a survival analysis model (636 v 1075 days till impaired).

CONCLUSION

Symptomatic seroconverting illness predisposes to more rapid neurocognitive impairment.

Expression of perforin on HIV-1-specific CD8+ lymphocytes after immunization with a gp120-depleted, whole-killed HIV-1 immunogen

We examined HIV-1 antigen specific intracellular expression of perforin on CD4+ and CD8+ lymphocytes in subjects with chronic HIV-1 infection on antiviral drug therapy after immunization with a gp120-depleted, whole killed HIV-1 immunogen (inactivated, gp120-depleted HIV-1 in IFA, REMUNE). Based upon previous results, we hypothesized that the restoration of adequate T helper immune responses by vaccination against HIV-1 could result in the augmentation of CD8+ lymphocyte immune responses measured as perforin expression. In the current study we observed an increase in the frequency of perforin in CD8+ lymphocytes in HIV infected individuals immunized with a gp120-depleted HIV-1 immunogen while on antiviral drug therapy. Furthermore, the frequency of HIV-specific CD8+ perforin expressing cells correlated with the T helper immune response as measured by the lymphocyte proliferative response (LPR). The induction of such responses with immunization may have direct antiviral consequences and is being studied in ongoing clinical trials.

The strategy of immunologic control of HIV-1 with structured treatment interruptions (STIs)

Structured treatment interruptions (STIs) have evolved as an experimental approach of interrupting highly active antiretroviral therapy (HAART) similar to cycles of cancer chemotherapy in order to develop immune control of HIV-1. There are multiple, ongoing clinical trials examining interruptions in antiviral therapy with and without immune-based therapies. If successful in developing immune control, STIs may be clinically useful but require large scale clinical trials to prove their utility and safety.

Clinical and molecular studies of a large family with desmin-associated restrictive cardiomyopathy

Patients with restrictive cardiomyopathy (RC) have impaired diastolic function, but intact systolic function until later stages of the disease, ultimately leading to heart failure. Primary RC is often sporadic, but also may be inherited in an autosomal dominant fashion, particularly the idiopathic forms. Recently there has been great interest in inherited cardiomyopathy associated with myocyte desmin deposition ('desminopathies'). In some such families, desmin or alpha-B crystallin gene mutation is the underlying cause, and the desmin accumulation affects skeletal muscle as well, usually causing skeletal myopathy. We describe a large family with apparent autosomal dominant inheritance of desmin-associated RC spanning four generations, with the age of onset and severity/rate of progression being highly variable. This family is relatively unique in that there is no symptom-based evidence of skeletal muscle involvement, and the known desminopathy and cardiomyopathy genes/loci have been ruled out. These data support literature suggesting that desmin deposition may be associated with different underlying gene defects, and that a novel desminopathy gene is responsible for the condition in this family.

Tumorigenic properties of neurofibromin-deficient neurofibroma Schwann cells

Dermal and plexiform neurofibromas are peripheral nerve sheath tumors that arise frequently in neurofibromatosis type 1. The goal of the present study was to examine the tumorigenic properties of neurofibromin-deficient human Schwann cells (SCs) that were found to represent a subset of SCs present in approximately half of the total neurofibromas examined. Highly enriched SC cultures were established from 10 dermal and eight plexiform neurofibromas by selective subculture using glial growth factor-2 and laminin. These cultures had low tumorigenic potential in classical in vitro assays yet several unique preneoplastic properties were frequently observed, including delayed senescence, a lack of density-limited growth, and a strong propensity to spontaneously form proliferative cell aggregates rich in extracellular matrix. Western blot analysis failed to detect full-length neurofibromin in any of the neurofibroma SC cultures, indicating that neurofibromin-deficient SCs had a substantial growth advantage. Immunohistochemical staining of the originating tumors showed the majority were comprised principally of neurofibromin-negative SCs, whereas the remainder contained both neurofibromin-negative and neurofibromin-positive SCs. Lastly, engraftment of neurofibromin-deficient SC cultures into the peripheral nerves of scid mice consistently produced persistent neurofibroma-like tumors with diffuse and often extensive intraneural growth. These findings indicate that neurofibromin-deficient SCs are involved in neurofibroma formation and, by selective subculture, provide a resource for the development of an in vivo model to further examine the role of these mutant SCs in neurofibroma histogenesis.

The changing economics of HIV care

New advances in human immunodeficiency virus (HIV) monitoring and therapeutics have led to dramatic changes in the course of HIV disease. We evaluated our closed clinic of 425 HIV patients over the period 1995-1998 to determine the cost effectiveness of these changes in care. We found that the costs of antiretroviral therapy tripled over the period of observation, but that these increases were largely offset by major declines in inpatient and home health expenditures. In addition, we found that annual mortality among our HIV patients had declined by 90%. We calculated that the cost per life-year gained is about $17,500, which compares favorably with medical expenditures for renal dialysis or advanced cardiac disease.

Outbreak of influenza in highly vaccinated crew of U.S. Navy ship

An outbreak of influenza A (H3N2) occurred aboard a U.S. Navy ship in February 1996, despite 95% of the crew's having been appropriately vaccinated. Virus isolated from ill crew members was antigenically distinct from the vaccination strain. With an attack rate of 42%, this outbreak demonstrates the potential for rapid spread of influenza in a confined population and the impact subsequent illness may have upon the workplace.

Cell-mediated immune responses to autologous virus in HIV-1-seropositive individuals after treatment with an HIV-1 immunogen

OBJECTIVE

We hypothesized that cell mediated immune responses to an HIV-1 immunogen (whole-killed, gp120-depleted HIV-1 in IFA, REMUNE) would include those to autologous virus.

METHODS

Five chronically HIV-1 infected individuals were examined for HIV-specific immune responses to their own virus (autologous viral antigen) after treatment with an HIV-1 immunogen.

RESULTS

Subjects had low proliferative responses to HIV and p24 antigens prior to immunization and mounted strong lymphocyte proliferative responses to the immunizing HIV-1 virus, native p24, and autologous viral antigen post immunization. Similarly, subjects produced low amounts of interferon-gamma in response to HIV and p24 antigens prior to immunization and increased their interferon-gamma production in response to HIV-1, native p24, and to autologous antigen post-immunization. Furthermore, beta-chemokine responses measured as migratory inhibitory protein-1beta production were low at baseline in response to HIV-1 and native p24 antigens and were enhanced post immunization to HIV-1, native p24, and autologous antigen.

CONCLUSIONS

In this study HIV-specific immune responses to autologous virus were observed after treatment with an HIV-specific immunogen.

Chromosome 17 loss-of-heterozygosity studies in benign and malignant tumors in neurofibromatosis type 1

Neurofibromatosis type 1 (NF1) is a common autosomal dominant condition characterized by benign tumor (neurofibroma) growth and increased risk of malignancy. Dermal neurofibromas, arising from superficial nerves, are primarily of cosmetic significance, whereas plexiform neurofibromas, typically larger and associated with deeply placed nerves, extend into contiguous tissues and may cause serious functional impairment. Malignant peripheral nerve sheath tumors (MPNSTs) seem to arise from plexiform neurofibromas. The NF1 gene, on chromosome segment 17q11.2, encodes a protein that has tumor suppressor function. Loss of heterozygosity (LOH) for NF1 has been reported in some neurofibromas and NF1 malignancies, but plexiform tumors have been poorly represented. Also, the studies did not always employ the same markers, preventing simple comparison of the frequency and extent of LOH among different tumor types. Our chromosome 17 LOH analysis in a cohort of three tumor types was positive for NF1 allele loss in 2/15 (13%) dermal neurofibromas, 4/10 (40%) plexiform neurofibromas, and 3/5 (60%) MPNSTs. Although the region of loss varied, the p arm (including TP53) was lost only in malignant tumors. The losses in the plexiform tumors all included sequences distal to NF1. No subtle TP53 mutations were found in any tumors. This study also reports the identification of both NF1 "hits" in plexiform tumors, further supporting the tumor suppressor role of the NF1 gene in this tumor type.

T-helper-cell proliferative responses to whole-killed human immunodeficiency virus type 1 (HIV-1) and p24 antigens of different clades in HIV-1-infected subjects vaccinated with HIV-1 immunogen (Remune)

The discovery of multiple subtypes of human immunodeficiency virus type 1 (HIV-1) worldwide has created new challenges for the development of both therapeutic and preventive AIDS vaccines. We examined T-helper proliferative responses to HIV-1 clade A, B, C, G, and E whole-killed virus and to HIV-1 clade G and B core (p24) antigens in HIV-1-infected subjects taking potent antiviral drugs who received HIV immunogen (Remune) therapeutic vaccination. Subjects who were immunized mounted strong proliferative responses to both whole virus and core antigens of the different clades. These results suggest that a whole-killed immunogen may have broad applications as a therapeutic as well as a preventive vaccine in the current multiclade HIV-1 pandemic.

Gastrointestinal manifestations of HIV infection

Since the beginning of the AIDS pandemic, gastrointestinal (GI) problems have been among the most common features of the disease. Despite the introduction of highly active antiretroviral therapy (HAART) in 1995 and 1996, most HIV-infected patients continue to have GI complications. The clinician must be able to diagnose and treat the opportunistic gastrointestinal infections and neoplasms that occur in the advanced AIDS patient, as well as the treatment-induced symptoms and non-HIV-related GI disorders that predominate in early HIV disease. This review addresses the GI manifestations of HIV, with particular emphasis on new developments in the era of highly effective therapy.

HIV-1-Specific CD4 helper function in persons with chronic HIV-1 infection on antiviral drug therapy as measured by ELISPOT after treatment with an inactivated, gp120-depleted HIV-1 in incomplete Freund's adjuvant

OBJECTIVE

We hypothesized that treatment of HIV-1-seropositive study subjects receiving potent antiviral therapy with an HIV-specific immune-based therapy would increase HIV-1-specific T-helper immune function.

DESIGN

10 HIV-1-seropositive study subjects receiving antiretroviral therapy were treated with an inactivated, gp120-depleted immunogen in IFA (HIV-1 immunogen, Remune) at baseline, week 12, and week 24.

METHODS

The frequency of HIV-1 antigen-stimulated interferon-gamma (IFN-gamma)-producing cells was determined by the ELISPOT assay.

RESULTS

Study subjects significantly increased their frequency of HIV-1-stimulated (p <. 001) or p24 antigen-stimulated (p <.01) IFN-gamma-producing cells after one, two, and three treatments of HIV-1 immunogen. Depletion of CD4 cells resulted in the strongest abrogation of the IFN-gamma response. The frequency of HIV-1 (r = 0.64; p =.0002) and p24 (r = 0. 72; p <.001) antigen-stimulated IFN-gamma-producing cells in the CD8-depleted population before and after treatment was associated with the lymphocyte-proliferative response.

CONCLUSIONS

Treatment with HIV-1 immunogen significantly enhanced the frequency of HIV-1-specific IFN-gamma-producing cells. Studies are ongoing to determine the relationship between this reversal of HIV-specific anergy and virologic outcomes.

NF1 mutation analysis using a combined heteroduplex/SSCP approach

Neurofibromatosis type 1 (NF1) is a common autosomal dominant disorder characterized predominantly by neurofibromas, café-au-lait spots, and Lisch nodules. The disease is caused by disruptive mutations of the large NF1 gene, with half of cases caused by new mutation. Less than 100 constitutional mutations have thus far been published, ranging from very large deletions to point mutations. We have pursued NF1 mutation analysis by heteroduplex analysis (HDA) and single-strand conformational polymorphism analysis (SSCP) of individual exons. We streamlined these techniques to eliminate the use of radioactivity, to apply both methods to the same PCR product, and to multiplex samples in gels. Applied simultaneously to a set of 67 unrelated NF1 patients, HDA and SSCP have thus far identified 26 mutations and/or variants in 45 of the 59 exons tested. Disease-causing mutations were found in 19% (13/67) of cases studied. Both techniques detected a variety of mutations including splice mutations, insertions, deletions, and point changes, with some overlap in the ability of each method to detect variants.

Analysis of CpG C-to-T mutations in neurofibromatosis type 1. Mutations in brief no. 129. Online

Neurofibromatosis type 1 (NF1) is a dominant disorder caused by mutations in the NF1 gene; approximately 100 NF1 gene mutations have been published. The CpG C-to-T transition is a frequent mutation mechanism in genetic disorders. To estimate its frequency in NF1, we employed a PCR-restriction digestion method to examine 17 CpGs in 65 patients, and also screened for a CpG nonsense transition (R1947X) that occurs in 1-2% of patients. The analysis revealed disease-related CpG C-to-T transitions (including a nonsense mutation that may be as frequent as R1947X) as well as a benign variant and another mutation at a CpG. Four patients showed CpG mutations in analysis of 18 sites (17 surveyed by restriction digest, plus the R1947X assay), including three C-to-T transitions and one C-to-G transversion. These 18 sites represent one-fifth of the 91 CpGs at which a C-to-T transition would result in a nonsense or nonconservative missense mutation. Thus, it is feasible that the CpG mutation rate at NF1 might be similar to that seen in other disorders with a high mutation rate, and that recurrent NF1 mutations may frequently reside at CpG sites.

Rab geranylgeranyl transferase alpha mutation in the gunmetal mouse reduces Rab prenylation and platelet synthesis

Few molecular events important to platelet biogenesis have been identified. Mice homozygous for the spontaneous, recessive mutation gunmetal (gm) have prolonged bleeding, thrombocytopenia, and reduced platelet alpha- and delta-granule contents. Here we show by positional cloning that gm results from a G-->A substitution mutation in a splice acceptor site within the alpha-subunit of Rab geranylgeranyl transferase (Rabggta), an enzyme that attaches geranylgeranyl groups to Rab proteins. Most Rabggta mRNAs from gm tissues skipped exon 1 and lacked a start codon. Rabggta protein and Rab geranylgeranyl transferase (GGTase) activity were reduced 4-fold in gm platelets. Geranylgeranylation and membrane association of Rab27, a Rab GGTase substrate, were significantly decreased in gm platelets. These findings indicate that geranylgeranylation of Rab GTPases is critical for hemostasis. Rab GGTase inhibition may represent a new treatment for thrombocytosis and clotting disorders.

Enhancement of HIV type 1 antigen-specific CD4+ T cell memory in subjects with chronic HIV type 1 infection receiving an HIV type 1 immunogen

We examined HIV-1 specific memory helper T immune responses in chronically HIV-infected subjects who received an immune-based therapy (HIV-1 immunogen, Remune). Subjects in this study exhibited significant increases (p < 0.05) in the frequency of helper T memory cells expressing interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) in response to HIV-1 antigens in vitro. The frequencies of HIV-specific memory T cells increased after successive immunizations and exhibited a correlation with the standard tritiated thymidine incorporation lymphocyte proliferation assay (r = 0.72, p < 0.0008). These results support the notion that HIV-specific memory immune responses can be stimulated in subjects with chronic HIV infection. Further investigations are warranted to determine whether the induction of such responses is associated with virologic control.

Increase in community-acquired methicillin-resistant Staphylococcus aureus at a Naval Medical Center

A retrospective review of methicillin-resistant Staphylococcus aureus isolates from the Naval Medical Center, San Diego, for the years 1994 through 1997, found that the annual number of community-acquired MRSA isolates increased during the period. These outpatient isolates were more likely than inpatient isolates to be sensitive to a greater number of antibiotics.

Culture of cytogenetically abnormal schwann cells from benign and malignant NF1 tumors

Dermal and plexiform neurofibromas are benign peripheral nerve sheath tumors that arise in neurofibromatosis type 1 (NF1). NF1 patients also have an increased risk of malignant peripheral nerve sheath tumors (MPNSTs), thought to arise in a subset of plexiform neurofibromas. Plexiform neurofibroma pathogenesis is poorly understood, despite the serious clinical problem posed by these tumors. The Schwann cell is hypothesized to be the cell type initially mutated and clonally expanded in plexiform neurofibromas. To test this hypothesis and search for genetic alterations involved in tumorigenesis, we established Schwann cell cultures from plexiform and dermal neurofibromas. Cytogenetic abnormalities were identified in 4/6 plexiform cultures (including one from a plexiform with a sarcomatous component) and 0/7 dermal neurofibroma Schwann cell cultures. There were no consistent chromosomal regions involved in the abnormal karyotypes, suggesting that plexiform tumors are heterogeneous and may bear a variety of primary and/or secondary genetic changes. This is the first study to show successful culturing of genetically abnormal Schwann cell lineages from plexiform neurofibromas. Thus, we present the strongest evidence yet to support the theory that the Schwann cell is the central component in the development of plexiform neurofibromas. This is a key finding for NF1 research, which will lead to further studies of the genetic and biochemical pathogenesis of these Schwann cell tumors. Genes Chromosomes Cancer 27:117-123, 2000.

Elastin region deletions in Williams syndrome

Williams syndrome (WS) is considered a contiguous gene syndrome, with most patients having a 1.5-Mb deletion of chromosome 7q11.23 containing the elastin gene and flanking genes. Studies of the frequency, extent, and origin of these deletions are ongoing in many labs to discover ultimately the molecular and pathogenetic basis for WS. An analysis of 9 sporadic WS families with typical phenotypes was performed by genotyping polymorphisms in the region. This study revealed deletions in all 9 patients, with one showing a novel deletion extending much further centromeric than any other WS deletions yet reported.

CXCR4 and CCR5 expression on CD4+ T cells in vivo and HIV-1 antigen beta-chemokine production in vitro after treatment with HIV-1 immunogen (REMUNE)

BACKGROUND

The chemokine receptors CXCR4 and CCR5 have been identified as the major coreceptors for HIV-1 on CD4+ cells and macrophages. The natural ligands for these receptors are SDF-1 and the beta-chemokines (MIP-1alpha, MIP-1beta, RANTES), respectively, and are the products of a variety of immune cells, including CD8+ T lymphocytes.

STUDY DESIGN/METHODS

We hypothesized that the ability to stimulate the natural ligands for these receptors using an immune based therapy might influence in vivo chemokine receptor expression.

RESULTS

In vivo CXCR4 expression remained stable after treatment with an HIV-1 Immunogen (REMUNE), whereas CCR5 expression on CD4+ T cells decreased (p < .05). Furthermore, HIV-1 antigen-specific production of beta-chemokines in vitro was also augmented (P < .05).

CONCLUSIONS

These preliminary results suggest that this HIV-1-specific immune-based therapy can stimulate antigen-specific beta-chemokine production in vitro and downregulate CCR5 receptor expression on CD4 cells in vivo.

Efficacy of influenza vaccination in HIV-infected persons. A randomized, double-blind, placebo-controlled trial

BACKGROUND

Although influenza vaccination is recommended in persons infected with HIV-1, its efficacy is unknown.

OBJECTIVE

To assess the immunogenicity, efficacy, and risks associated with influenza vaccination in persons infected with HIV-1.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Outpatient military clinic.

PATIENTS

102 patients with HIV-1 infection.

INTERVENTION

Influenza vaccine (n = 55) or saline placebo (n = 47).

MEASUREMENTS

Influenza antibody titers, CD4+ cell counts, and plasma HIV-1 RNA levels at baseline, 1 month after immunization, and 3 months after immunization; viral cultures from persons presenting with respiratory illness; and respiratory symptom interview.

RESULTS

Twenty-three placebo recipients (49%) and 16 vaccine recipients (29%) reported respiratory symptoms (P = 0.04). Ten placebo recipients but no vaccine recipients had laboratory-confirmed symptomatic influenza (P < 0.001) (protective efficacy, 100% [95% CI, 73% to 100%]). No effect on plasma HIV-1 RNA levels or CD4+ cell counts was noted.

CONCLUSION

Influenza vaccination is highly effective in HIV-1-infected persons and does not seem to be associated with substantial changes in viral load or CD4 cell count.

Exon 10b of the NF1 gene represents a mutational hotspot and harbors a recurrent missense mutation Y489C associated with aberrant splicing

PURPOSE

To analyze the spectrum and frequency of NF1 mutations in exon 10b.

METHODS

Mutation and sequence analysis was performed at the DNA and cDNA level.

RESULTS

We identified nine exon 10b mutations in 232 unrelated patients. Some mutations were recurrent (Y489C and L508P), others were unique (1465-1466insC and IVS10b+2delTAAG). Surprisingly, at the RNA level, Y489C causes skipping of the last 62 nucleotides of exon 10b. Another recurrent mutation, L508P, is undetectable by the Protein Truncation Test.

CONCLUSION

As exon 10b shows the highest mutation rate yet found in any of the 60 NF1 exons, it should be implemented with priority in mutation analysis.

Phenotypic analysis of human immunodeficiency virus (HIV) type 1 cell-mediated immune responses after treatment with an HIV-1 immunogen

It was hypothesized that immune recognition could be stimulated with combined immune-based and potent antiviral drug therapies. This study examined human immunodeficiency virus type 1 (HIV-1)-specific lymphocyte proliferation before and after treatment with an inactivated HIV-1 immunogen in 15 chronically infected HIV-1 seropositive subjects. Lymphocyte proliferation to the immunizing antigen (gp120-depleted HIV-1; P<.001), purified native p24 (P<.001), and recombinant p24 (P<.05) increased after treatment with the HIV-specific immune-based therapy. By HIV-1 antigen-specific flow cytometry, T helper CD4 lymphocytes, CD8 lymphocytes, and NK cells (all P<.001) were the predominant cell types proliferating in vitro after treatment. Additional phenotyping of proliferating cells revealed predominantly CD4 and CD8 memory (both P<.001) phenotypes. This study supports the concept that in vitro lymphocyte proliferation to HIV-1 antigens, augmented after treatment with an inactivated HIV-1 immunogen, involves primarily CD4 and CD8 cell memory immune responses.