Long-acting HIV Treatments: Study Design, Logistics, and Access.

New long-acting HIV treatment products have the potential to change the HIV epidemic in the United States and globally. Phase 3 clinical trials of HIV treatments tend to underrepresent populations bearing a disproportionate burden of the HIV epidemic-including women, racial minorities, trans and gender-diverse people, older adults, the unhoused, people who inject drugs, those in rural areas, individuals with mental illness, and other marginalized groups. These populations commonly face significant challenges in adhering to daily HIV treatment regimens. Conducting clinical trials of long-acting treatment targeting specific unmet medical needs of these populations can improve understanding of optimal care approaches, broaden the indication for use of long-acting products, and inform treatment guidelines, all of which can influence reimbursement and access policies. Innovative trial designs and programmatic implementation can improve inclusivity for long-acting therapy. This article summarizes discussions of a multistakeholder workshop on study designs for long-acting HIV treatments.

Genetic and clinical heterogeneity in eIF2B-related disorder.

Eukaryotic initiation factor 2B (eIF2B)-related disorders are heritable white matter disorders with a variable clinical phenotype (including vanishing white matter disease and ovarioleukodystrophy) and an equally heterogeneous genotype. We report 9 novel mutations in the EIF2B genes in our subject population, increasing the number of known mutations to more than 120. Using homology modeling, we have analyzed the impact of novel mutations on the 5 subunits of the eIF2B protein. Although recurrent mutations have been found at CpG dinucleotides in the EIF2B genes, the high incidence of private or low frequency mutations increases the challenge of providing rapid genetic confirmation of this disorder, and limits the application of EIF2B screening in cases of undiagnosed leukodystrophy.

Definition of the unique human extraocular muscle allotype by expression profiling.

The extraocular muscles (EOMs) are a unique group of specialized muscles that are anatomically and physiologically distinct from other skeletal muscles. Perhaps the most striking characteristic of the EOMs is their differential sensitivity to disease. EOMs are spared in Duchenne's muscular dystrophy (DMD) despite widespread involvement of other skeletal muscles. Conversely, they are early and prominent targets in myasthenia gravis and mitochondrial myopathies. It is unclear how EOMs achieve such specialization or a differential response to diseases; however, this has been attributed to a unique, group-specific pattern of gene expression or "allotype." To begin to address these issues as well as define the human EOM allotype, we analyzed the human EOM transcriptome using oligonucleotide-based expression profiling. Three hundred thirty-eight genes were found to be differentially expressed in EOM compared with quadriceps femoris limb muscle, using a twofold cutoff. Functional characterization revealed expression patterns corresponding to known metabolic and structural properties of EOMs such as expression of EOM-specific myosin heavy chain (MYH13) and high neural, vascular, and mitochondrial content, suggesting that the profiling was sensitive and specific. Genes related to myogenesis, stem cells, and apoptosis were detected at high levels in normal human EOMs, suggesting that efficient and continuous regeneration and/or myogenesis may be a mechanism by which the EOMs remain clinically and pathologically spared in diseases such as DMD. Taken together, this study provides insight into how human EOMs achieve their unique structural, metabolic, and pathophysiological properties.

Expression profiling reveals metabolic and structural components of extraocular muscles.

The extraocular muscles (EOM) are anatomically and physiologically distinct from other skeletal muscles. EOM are preferentially affected in mitochondrial myopathies, but spared in Duchenne's muscular dystrophy. The anatomical and pathophysiological properties of EOM have been attributed to their unique molecular makeup: an allotype. We used expression profiling to define molecular features of the EOM allotype. We found 346 differentially expressed genes in rat EOM compared with tibialis anterior, based on a twofold difference cutoff. Genes required for efficient, fatigue-resistant, oxidative metabolism were increased in EOM, whereas genes for glycogen metabolism were decreased. EOM also showed increased expression of genes related to structural components of EOM such as vessels, nerves, mitochondria, and neuromuscular junctions. Additionally, genes related to specialized functional roles of EOM such as the embryonic and EOM-specific myosin heavy chains and genes for muscle growth, development, and/or regeneration were increased. The EOM expression profile was validated using biochemical, structural, and molecular methods. Characterization of the EOM expression profile begins to define gene transcription patterns associated with the unique anatomical, metabolic, and pathophysiological properties of EOM.

Megalencephalic leukoencephalopathy with subcortical cysts.

Megalencephalic leukoencephalopathy with subcortical cysts is one of the newly described white-matter disorders for which recognition has been brought about by advances in imaging technology. The essential diagnostic features include megalencephaly noted in infancy, motor disability in the form of spasticity, ataxia, occasional seizures, mild cognitive decline, and slow progression. Magnetic resonance imaging (MRI) shows bilateral extensive white-matter changes with cysts in the temporal regions. Based on the clinical and MRI features, megalencephalic leukoencephalopathy with subcortical cysts can be distinguished from other conditions (ie, Alexander's disease, Canavan's disease, glutaricaciduria type I) that present in infancy with megalencephaly. Megalencephalic leukoencephalopathy with subcortical cysts is an autosomal recessive disorder, and mutations in the MLC1 gene have now been shown to cause this condition. Several genotypic and phenotypic variations have been described. In India, megalencephalic leukoencephalopathy with subcortical cysts occurs predominantly in the Agarwal community. A common mutation in the MLC1 gene has been seen in 31 Agarwal patients, which suggests a founder effect.

A potential role for mast cells in the of bFGF from normal myocytes during angiogenesis in vivo.

Basic fibroblast growth factor (bFGF) is a potent angiogenic factor produced by cells of mesodermal and neuroectodermal origin. Despite numerous advances, the precise mechanism of bFGF release from cells still remains unknown. Upon release from cells, the protein is stored and protected in the extracellular matrix by binding to heparan sulfate proteoglycans. A number of reports suggest that degrading enzymes secreted by mast cells may play a role in the release of bFGF from connective tissue stores. Additionally, mast cells are believed to play a role in the formation of new blood vessels. In this report, we studied the events involved in neovascularization using a well-characterized model of angiogenesis in rabbits where neovascularization is induced by transfer of a well-perfused rectus abdominis muscle flap to an ischemic limb. Using this model, we demonstrate that bFGF expression is induced in normal myofibers and bFGF is released in the wound fluid at the ischemic/nonischemic interface. The highest concentrations of bFGF were detected on days 14 and 21 postoperation. We also show that the number of mast cells and their degranulation correlate with the release of bFGF from adjacent muscle tissue and the appearance of the growth factor in the wound fluid. There appears to exist a temporal correlation between number of mast cells, their degranulation, and the release of bFGF during angiogenesis in vivo.

Propensity for paternal inheritance of de novo mutations in Alexander disease.

De novo dominant mutations in the GFAP gene have recently been associated with nearly all cases of Alexander disease, a rare but devastating neurological disorder. These heterozygous mutations must occur very early in development and be present in nearly all cells in order to be detected by the sequencing methods used. To investigate whether the mutations may have arisen in the parental germ lines, we determined the parental chromosome bearing the mutations for 28 independent Alexander disease cases. These cases included 17 different missense mutations and one insertion mutation. To enable assignment of the chromosomal origin of the mutations, six new single nucleotide polymorphisms in the GFAP gene were identified, bringing the known total to 26. In 24 of the 28 cases analyzed, the paternal chromosome carried the GFAP mutation (P < 0.001), suggesting that they predominantly arose in the parental germ line, with most occurring during spermatogenesis. No effect of paternal age was observed. There has been considerable debate about the magnitude of the male to female germ line mutation rate; our ratio of 6:1 is consistent with indirect estimates based on the rate of evolution of the sex chromosome relative to the autosomic chromosomes.