Overcoming barriers and stigma: new frontiers in solid organ transplantation for people with HIV.

There is a growing need for solid organ transplantation (SOT) for people living with human immunodeficiency virus (HIV). With the advent of antiretroviral therapy, people living with HIV are experiencing increased life expectancies and are, therefore, developing more comorbidities, including end-stage organ disease. In cases of advanced organ failure, SOT is often the best therapeutic option to improve quality of life and overall survival. As organ shortages persist, transplantation of organs from donors with HIV to recipients with HIV has become a potential therapeutic option. This article first reviews the current state of organ transplantation from donors without HIV to recipients with HIV (HIV D-/R+) by organ and discusses key lessons learned from these transplant trials, including those about drug-drug interactions, rejection, and opportunistic infections. It then explores transplantation from donors with HIV to recipients with HIV (HIV D+/R+), a new frontier. Finally, it investigates challenges of implementation, including public awareness and regulatory requirements, and explores future directions for SOT in people living with HIV.

Doping evaluation of InP nanowires for tandem junction solar cells.

In order to push the development of nanowire-based solar cells further using optimized nanowire diameter and pitch, a doping evaluation of the nanowire geometry is necessary. We report on a doping evaluation of n-type InP nanowires with diameters optimized for light absorption, grown by the use of metal-organic vapor phase epitaxy in particle-assisted growth mode using tetraethyltin (TESn) as the dopant precursor. The charge carrier concentration was evaluated using four-probe resistivity measurements and spatially resolved Hall measurements. In order to reach the highest possible nanowire doping level, we set the TESn molar fraction at a high constant value throughout growth and varied the trimethylindium (TMIn) molar fraction for different runs. Analysis shows that the charge carrier concentration in nanowires grown with the highest TMIn molar fraction (not leading to kinking nanowires) results in a low carrier concentration of approximately 10(16) cm(-3). By decreasing the molar fraction of TMIn, effectively increasing the IV/III ratio, the carrier concentration increases up to a level of about 10(19) cm(-3), where it seems to saturate. Axial carrier concentration gradients along the nanowires are found, which can be correlated to a combination of changes in the nanowire growth rate, measured in situ by optical reflectometry, and polytypism of the nanowires observed in transmission electron microscopy.

InAs Nanowire Transistors with Multiple, Independent Wrap-Gate Segments.

We report a method for making horizontal wrap-gate nanowire transistors with up to four independently controllable wrap-gated segments. While the step up to two independent wrap-gates requires a major change in fabrication methodology, a key advantage to this new approach, and the horizontal orientation more generally, is that achieving more than two wrap-gate segments then requires no extra fabrication steps. This is in contrast to the vertical orientation, where a significant subset of the fabrication steps needs to be repeated for each additional gate. We show that cross-talk between adjacent wrap-gate segments is negligible despite separations less than 200 nm. We also demonstrate the ability to make multiple wrap-gate transistors on a single nanowire using the exact same process. The excellent scalability potential of horizontal wrap-gate nanowire transistors makes them highly favorable for the development of advanced nanowire devices and possible integration with vertical wrap-gate nanowire transistors in 3D nanowire network architectures.

Formation of nanogaps in InAs nanowires by selectively etching embedded InP segments.

We present a method to fabricate nanometer scale gaps within InAs nanowires by selectively etching InAs/InP heterostructure nanowires. We used vapor-liquid-solid grown InAs nanowires with embedded InP segments of 10-60 nm length and developed an etching recipe to selectively remove the InP segment. A photo-assisted wet etching process in a mixture of acetic acid and hydrobromic acid gave high selectivity, with accurate removal of InP segments down to 20 nm, leaving the InAs wire largely unattacked, as verified using scanning electron and transmission electron microscopy. The obtained nanogaps in InAs wires have potential as semiconducting electrodes to investigate electronic transport in nanoscale objects. We demonstrate this functionality by dielectrophoretically trapping 30 nm diameter gold nanoparticles into the gap.

Evaluation of RAD51C as cancer susceptibility gene in a large breast-ovarian cancer patient population referred for genetic testing.

Despite extensive analysis of the BRCA1 and BRCA2 genes, germline mutations are detected in <20% of families with a presumed genetic predisposition for breast and ovarian cancer. Recent literature reported RAD51C as a new breast cancer susceptibility gene. In this study, we report the analysis of 410 patients from 351 unrelated pedigrees. All were referred for genetic testing and we selected families with at least one reported case of ovarian cancer in which BRCA1&2 mutations were previously ruled out. We analyzed the coding exons, intron-exons boundaries, and UTRs of RAD51C. Our mutation analysis did not reveal any unequivocal deleterious mutation. In total 12 unique sequence variations were identified of which two were novel. Our study and others suggest a low prevalence of RAD51C mutations with an exception for some founder populations. This observation is in favor of the rare allele hypothesis in the debate over the nature of the genetic contribution to individual susceptibility to breast and ovarian cancer and further genome-wide studies in high risk families are warranted.

Distal myopathy with upper limb predominance caused by filamin C haploinsufficiency.

OBJECTIVE: In this study, we investigated the detailed clinical findings and underlying genetic defect in 3 presumably related Bulgarian families displaying dominantly transmitted adult onset distal myopathy with upper limb predominance. METHODS: We performed neurologic, electrophysiologic, radiologic, and histopathologic analyses of 13 patients and 13 at-risk but asymptomatic individuals from 3 generations. Genome-wide parametric linkage analysis was followed by bidirectional sequencing of the filamin C (FLNC) gene. We characterized the identified nonsense mutation at cDNA and protein level. RESULTS: Based on clinical findings, no known myopathy subtype was implicated in our distal myopathy patients. Light microscopic analysis of affected muscle tissue showed no specific hallmarks; however, the electron microscopy revealed changes compatible with myofibrillar myopathy. Linkage studies delineated a 9.76 Mb region on chromosome 7q22.1-q35 containing filamin C (FLNC), a gene previously associated with myofibrillar myopathy. Mutation analysis revealed a novel c.5160delC frameshift deletion in all patients of the 3 families. The mutation results in a premature stop codon (p.Phe1720LeufsX63) that triggers nonsense-mediated mRNA decay. FLNC transcript levels were reduced in muscle and lymphoblast cells from affected subjects and partial loss of FLNC in muscle tissue was confirmed by protein analysis. CONCLUSIONS: The FLNC mutation that we identified is distinct in terms of the associated phenotype, muscle morphology, and underlying molecular mechanism, thus extending the currently recognized clinical and genetic spectrum of filaminopathies. We conclude that filamin C is a dosage-sensitive gene and that FLNC haploinsufficiency can cause a specific type of myopathy in humans.

Analysis of FOXG1 Is Highly Recommended in Male and Female Patients with Rett Syndrome.

We screened a cohort of 5 male and 20 female patients with a Rett spectrum disorder for mutations in the coding region of FOXG1, previously shown to cause the congenital variant of Rett syndrome. Two de novo mutations were identified. The first was a novel missense mutation, p.Ala193Thr (c.577G>A), in a male patient with congenital Rett syndrome, and the second was the p.Glu154GlyfsX301 (c.460dupG) truncating mutation in a female with classical Rett syndrome, a mutation that was previously reported in an independent patient. The overall rate of FOXG1 mutations in our cohort is 8%. Our findings stress the importance of FOXG1 analysis in male patients with Rett syndrome and in female patients when mutations in the MECP2 and CDKL5 genes have been excluded.

Multiplex ligation-dependent probe amplification to detect subtelomeric rearrangements in routine diagnostics.

Subtelomeric rearrangements are believed to be responsible for 5-7% of idiopathic mental retardation cases. Due to the relative complexity and high cost of the screening methods used till now, only preselected patient populations including mostly the more severely affected cases have been screened. Recently, multiplex ligation-dependent probe amplification (MLPA) has been adapted for use in subtelomeric screening, and we have incorporated this technique into routine diagnostics of our laboratory. Since the evaluation of MLPA as a screening method, we tested 275 unselected patients with idiopathic mental retardation and detected 12 possible subtelomeric aberrations: a der(11)t(11;20)(qter;qter), a 19pter duplication, a der(18)t(18;10)(qter; pter), a 15qter deletion, a 8pter deletion, a 6qter deletion, a der(X)t(X;1)(pter;qter), a der(X)t(X;3)(pter;pter), a 5qter duplication, a 3pter deletion, and two 3qter duplications. The patients can be subdivided into two groups: the first containing de novo rearrangements that are likely related to the clinical presentation of the patient and the second including aberrations also present in one of the parents that may or may not be causative of the mental retardation. In our patient cohort, five (1.8%) subtelomeric rearrangements were de novo, three (1.1%) rearrangements were familial and suggestively disease causing, and four (1.5%) were possible polymorphisms. This high frequency of subtelomeric abnormalities detected in an unselected population warrants further investigation about the feasibility of routine screening for subtelomeric aberrations in mentally retarded patients.

An optimized DHPLC protocol for molecular testing of the EXT1 and EXT2 genes in hereditary multiple osteochondromas.

Hereditary multiple osteochondromas (MO) is an autosomal dominant bone disorder characterized by the presence of bony outgrowths (osteochondromas or exostoses) on the long bones. MO is caused by mutations in the EXT1 or EXT2 genes, which encode glycosyltransferases implicated in heparan sulfate biosynthesis. Standard mutation analysis performed by sequencing analysis of all coding exons of the EXT1 and EXT2 genes reveals a mutation in approximately 80% of the MO patients. We have now optimized and validated a denaturing high-performance liquid chromatography (DHPLC)-based protocol for screening of all EXT1- and EXT2-coding exons in a set of 49 MO patients with an EXT1 or EXT2 mutation. Under the optimized DHPLC conditions, all mutations were detected. These include 20 previously described mutations and 29 new mutations - 20 new EXT1 and nine new EXT2 mutations. The protocol described here, therefore, provides a sensitive and cost-sparing alternative for direct sequencing analysis of the MO-causing genes.

Absence of constitutional Y chromosome AZF deletions in patients with testicular germ cell tumors.

OBJECTIVES: To investigate the frequency of azoospermia factor (AZF) deletions in Dutch patients with testicular germ cell tumors (TGCTs). Reduced fertility is associated with TGCTs and reduced fertility and TGCTs might share genetic risk factors according to the testicular dysgenesis hypothesis. Up to 8% of infertility and reduced fertility in the general male population can be explained by the presence of constitutional deletions of part of the long arm of the Y chromosome (Yq11), referred to as the AZF region. METHODS: In 112 patients with TGCT, screening for constitutional deletions in the AZF region was performed by multiplex polymerase chain reaction analysis in DNA extracted from peripheral blood lymphocytes. A set of 24 primer pairs, of which 20 primer pairs are homologous to previously identified and mapped sequenced tag sites within the AZF region were used. RESULTS: No deletions in the Yq11 region were detected in any of the 112 patients. CONCLUSIONS: Large Y chromosome microdeletions in the AZF region are not a major contributor to the development of TGCT and TGCT-associated reduced fertility.

The clinical pharmacokinetics of a new pharmacokinetically enhanced formulation of amoxicillin/clavulanate.

BACKGROUND: A new oral pharmacokinetically enhanced formulation of the broad-spectrum antibiotic amoxicillin/clavulanate has been developed to provide more effective therapy against resistant pathogens than is provided by currently available formulations by maintaining therapeutically useful plasma amoxicillin concentrations for a longer period after dosing. OBJECTIVE: This study explored the pharmacokinetics of the new oral formulation of amoxicillin/clavulanate in healthy male and female subjects. METHODS: A single oral dose of pharmacokinetically enhanced amoxicillin/clavulanate (2000/125 mg; 16:1 ratio) was administered to subjects at the start of a meal. After dosing, blood samples were collected at frequent intervals up to 12 hours, and plasma was assayed for amoxicillin and clavulanate concentrations using validated procedures. The new formulation consisted of 1 layer of immediate-release amoxicillin and clavulanate and another of sustained-release amoxicillin in a proportion such that for an amoxicillin minimum inhibitory concentration (MIC) of 4 microg/mL, the time above the MIC (T >MIC) would be approximately > or = 40% over a 12-hour dosing interval. RESULTS: The study enrolled 24 and 31 healthy male and female subjects, respectively. Their mean age was 35 years (range, 18-58 years) and mean body weight was 69 kg (range, 51-86 kg). After the expected sharp peak in plasma amoxicillin concentration, there appeared to be a slower decline with the pharmacokinetically enhanced formulation than is usually seen with conventional formulations, and there was evidence of a second amoxicillin absorption phase. The mean T >MIC for an amoxicillin MIC of 4 microg/mL was 49.4% of a 12-hour dosing interval, a value that cannot be achieved with existing approved doses and formulations of amoxicillin/clavulanate. By 12 hours, plasma amoxicillin concentrations were very low (approximately 0.05 microg/mL), suggesting no expectation of notable dose-to-dose accumulation on repeat dosing with a BID regimen. The terminal half-lives of amoxicillin (1.27 hours) and clavulanate (1.03 hours) with the new formulation were similar to those of existing formulations of amoxicillin/clavulanate. No deaths or serious adverse events were reported. CONCLUSIONS: The enhanced pharmacokinetic profile of amoxicillin/clavulanate seen in this study suggests that this formulation is likely to be highly effective for the oral treatment of infections caused by bacteria--including beta-lactamase-producing organisms--and strains with amoxicillin MICs < or = 4 microg/mL.

The M34T allele variant of connexin 26.

GJB2 encodes the protein Connexin 26, one of the building blocks of gap junctions. Each Connexin 26 molecule can oligomerize with five other connexins to form a connexon; two connexons, in turn, can form a gap junction. Because mutations in GJB2 are the most common cause of congenital severe-to-profound autosomal recessive nonsyndromic hearing loss, the effect of the Connexin 26 allele variants on this dynamic 'construction' process and the function of any gap junctions that do form is particularly germane. One of the more controversial allele variants, M34T, has been hypothesized to cause autosomal dominant nonsyndromic hearing loss. In this paper, we present clinical and genotypic data that refutes this hypothesis and suggests that the effect of the M34T allele variant may be dependent on the mutations segregating in the opposing allele.

Classical Friedreich's ataxia and its genotype.

Fourteen patients with classical features of Friedreich's ataxia (FRDA) were examined. The clinical diagnosis of FRDA was afterwards confirmed in all patients by the appropriate DNA investigation which showed markedly increased amounts of GAA repeats on both alleles of the frataxin gene. None of our patients presented with atypical features such as late-onset FRDA, FRDA with retained deep tendon reflexes or with a very slow course. Five of them are not yet confined to a wheelchair. But for 1 patient who died at age 36 years and had the largest number of GAA repeats on both alleles, there was no significant correlation between number of repeats in the shortest allele, age at onset, age at wheelchair dependence, duration of the disease and main clinical signs. All patients but 3 had between 500 and 1,050 GAA repeats. The 3 patients with, respectively, 400, 450 and 500 repeats on the shortest allele had a clinical course comparable to the other patients. Even in the case of variations in the number of repeats in the same sibship, there were only modest differences between the siblings concerning age at onset of the disease, symptoms and signs and age at wheelchair dependence. There were no qualitative differences in the main clinical features and laboratory investigations in the full-blown phase of the disorder. Molecular biology has become a major element in the diagnosis of FRDA. DNA testing for FRDA should be applied to every case of idiopathic autosomal recessive or sporadic ataxia. However, the clinical features of FRDA remain fully characteristic in many patients and keep their diagnostic value.

Determination of the carrier frequency of the common GJB2 (connexin-26) 35delG mutation in the Belgian population using an easy and reliable screening method.

Mutations in the gene GJB2, encoding the gap-junction protein connexin-26, have been shown to be a major cause of nonsyndromic recessive deafness (NSRD). A single mutation in the GJB2 gene accounts for the majority of NSRD in many different populations. This mutation represents a deletion of a guanine within a stretch of six Gs between nucleotide positions +30 and +35 of the GJB2 cDNA (35delG). Molecular detection of the 35delG mutation is usually performed by direct sequencing analysis of PCR products, or by allele-specific PCR analysis. To screen for this mutation, we developed an easier and more reliable method, based on the principle of PCR-mediated site-directed mutagenesis (PSDM), followed by a BsiYI digestion. We tested 360 unrelated unaffected Belgian individuals for heterozygosity of the 35delG mutation and found a carrier frequency of 1 in 40 (95% CI, 1 in 30 to 1 in 60). As our new screening method is simple and reliable in use, and detects a mutation responsible for a significant part of NSRD, it may find widespread use in DNA diagnostics.

CAG repeat contraction in the androgen receptor gene in three brothers with mental retardation.

We report on three brothers with mental retardation and a contracted CAG repeat in the androgen receptor (AR) gene. It is known that expansion of the CAG repeat in this gene leads to spinal and bulbar muscular atrophy (SBMA or Kennedy disease); however, contracted repeats have not yet been implicated in disease. As the range of the length of CAG repeats in the AR gene, like those of other genes associated with dynamic mutations, follows a normal distribution, the theoretical possibility of disease at both ends of the distribution should be considered.

Incomplete EcoRI digestion may lead to false diagnosis of fragile X syndrome.

Molecular diagnosis of fragile X syndrome is usually performed using Southern blot analysis of DNA digested with EcoRI. In the course of diagnostic studies, we observed that a specific EcoRI restriction site in the fragile X gene (FMR1) is sometimes refractory to digestion, generating additional fragments on a Southern blot suggestive of a full mutation in FMR1. This may lead to a false-positive diagnosis of fragile X syndrome. Such additional bands are avoided by the use of HindIII instead of EcoRI. Therefore, we recommend the use of HindIII for the molecular diagnosis of fragile X syndrome.

Copper treatment increases recombinant baculovirus production and polyhedrin and p10 expression.

Treatment with 2 mM CuSO4 was used to induce a Drosophila melanogaster metallothionein (Mtn) promoter that had been cloned into a recombinant baculovirus. Careful study revealed that the Mtn promoter functioned as an inducible, if somewhat "leaky" promoter within the context of baculovirus-infected cells. In the process of generating a recombinant-baculovirus, it was discovered that post-transfection treatment with copper resulted in a 10-fold increase in the production of recombinant virus. This effect on virus production was specific to transfection, as treatment of infected cells with copper did not increase the production of virus. Treatment of infected cells with copper did, however, extend the period of expression of the polyhedrin and p10 proteins by at least 12 h. These findings have practical applications for the production of recombinant baculoviruses and the subsequent expression of foreign proteins using baculovirus expression vectors.

Mildly impaired water maze performance in male Fmr1 knockout mice.

Fmr1 knockout mice constitute a putative model of fragile X syndrome, the most common form of heritable mental disability in humans. We have compared the performance of transgenic mice with an Fmr1 knockout with that of normal littermates in hidden- and visible-platform water maze learning, and showed that knockouts exhibit subnormal spatial learning abilities and marginal motor performance deficits. During 12 training trials of the hidden-platform task, escape latency and path length decreased significantly in knockouts and control littermates, and no effect of genotype was found. During four ensuing reversal trials, however, significant differences were found between knockouts and control littermates both in escape latency and path length. During the visible-platform condition, the reversal trials also revealed a difference between knockouts and normal littermates in escape latency, but not in path length. Possibly due to marginal motor incapacity, knockouts swam significantly slower than controls during these latter trials. During both probe trials of the hidden-platform task, knockouts as well as normal littermates spent more time in the target quadrant than in the other quadrants, and percent of time spent in the target quadrant was the same in both groups; swimming velocity was not significantly different between knockouts and normal littermates during these trials. Entries in the target area during the probe trials did show a significant effect of genotype on number of entries. The present results largely confirm and extend our previous findings. Impaired spatial abilities in Fmr1 knockouts might have been due to relatively low response flexibility or high memory interference in Fmr1 knockouts. It remains unclear, however, which brain region or neurochemical system might be involved in these disabilities. We conclude that Fmr1 knockout mice might be a valid model of fragile X mental retardation.