Targeting the third '90': introducing the viral load champion

Objective: To move closer to achieving the third target of the UNAIDS 90-90-90 goals, we prospectively implemented a viral load (VL) champion (VLC) program aimed at enhancing VL monitoring and recognition of treatment failure. Design: Three clinics in eThekwini, Kwa-Zulu Natal (low-, medium- and high-volume, encompassing 9184 patients overall) were each assigned a VLC. We employed a descriptive analysis (chart audit) to compare the pre-intervention period to a 1-year post-intervention period. The number of patients with a VL test performed 6 and 12 months after the intervention was calculated as a proportion of VL tests due at those time points (VL completion rate). Results: The pre-implementation VL completion rate at the three sites was respectively 68% (140/205 patients), 54% (84/155 patients) and 64% (323/504 patients), and the 6-month post-implementation completion rate increased to 83% (995/1194 patients), 90% (793/878 patients) and 99% (3101/3124 patients) (P < 0.0001 for each site). VL completion rates remained significantly higher at 12 months post-implementation, with an average cumulative VL completion rate of >90% across all facilities. Conclusion: We demonstrate a successful, multifaceted, quality-improvement intervention centered on a clinic-level VLC which, taken to scale, has important implications for attaining the third UNAIDS 90-90-90 target.

Adapting and validating a measure of diabetes-specific self-compassion

AIMS

Self-compassion (SC), or treating oneself with kindness when dealing with personal challenges, has not been rigorously examined in people with T1D. SC has been shown to buffer against negative emotions and to be linked to improved health outcomes, but diabetes-specific SC has not been studied. This study aimed to adapt the Self-Compassion Scale and validate it for a diabetes-specific population.

METHODS

We developed and validated a diabetes-specific version of the Self-Compassion Scale (Neff, 2003) in a sample of adults with T1D (N=542; 65% female; 97% non-Hispanic White; M age 41, SD=15.7; M A1c=7.3, SD=1; 72% insulin pump users; 50% continuous glucose monitoring [CGM] users). Confirmatory factor analyses (CFA), and reliability and construct validity analyses were conducted. Validity measures included diabetes distress, diabetes empowerment, diabetes numeracy, and A1c.

RESULTS

A two-factor bi-factor structure showed best fit, providing support for use of the adapted scale (SCS-D) as a unitary construct. The 19-item unidimensional SCS-D demonstrated excellent internal consistency (ɑ=0.94; range of item-total correlations: 0.52-0.71) and construct validity. As hypothesized, higher SCS-D was associated with less distress, greater empowerment, and lower A1c, and was not associated with numeracy.

CONCLUSIONS

The SCS-D is a reliable and valid measure of diabetes-specific self-compassion in adults with T1D.

Specific Immunotherapy of Experimental Myasthenia by Genetically Engineered APCs

Although treatment of MG with general immunosuppressive agents is often effective, it has important drawbacks, including suppression of the immune system as a whole, with the risks of infection and neoplasia, and numerous other adverse side effects. Ideally, treatment of MG should eliminate the specific pathogenic autoimmune response to AChR, without otherwise suppressing the immune system or producing other adverse side effects. Although antibodies to AChR are directly responsible for the loss of AChRs at neuromuscular junctions in MG, the AChR antibody response is T cell-dependent, and immunotherapy directed at T cells can abrogate the autoantibody response, with resulting benefit. As in other autoimmune diseases, the T cell response in MG is highly heterogeneous. The design of specific immunotherapy must take this heterogeneity into account and target the entire repertoire of AChR-specific T cells. We describe our investigation of a novel strategy for specific immunotherapy of MG, involving gene transfer to convert antigen-presenting cells (APCs) to "guided missiles" that target AChR-specific T cells, and that induce apoptosis and elimination of those T cells. This strategy uses the ability of APCs from a given individual to present the entire spectrum of AChR epitopes unique for that individual, and thereby to target the entire repertoire of antigen-specific T cells of the same individual. Using viral vectors, we have genetically engineered the APCs to process and present the most important domain of the AChR molecule, and to express a "warhead" of Fas ligand (FasL) to eliminate the activated AChR-specific T cells with which they interact. Our results show that the APCs express the appropriate gene products, and effectively and specifically eliminate AChR-specific T cells by the Fas/FasL pathway, while sparing T cells of other specificities.

Specific immunotherapy by genetically engineered APCs: the "guided missile" strategy

We tested the hypothesis that APCs genetically engineered to present an Ag and to express Fas ligand (FasL) simultaneously can target and eliminate Ag-specific T cells. Transgenic T cells specific for influenza hemagglutinin (HA) were used as targets. We prepared recombinant vaccinia virus vectors (VVV) to transfer the gene constructs individually or simultaneously into APCs. We prevented unwanted viral replication by attenuating the VVVs with psoralen-UV light treatment. For presentation of the HA Ag, APCs were transduced with cDNA for HA flanked by sequences of the lysosome-associated membrane protein that direct efficient processing and presentation of the Ag by APCs. As a "warhead" for the APCs, we transduced them with the gene for FasL, which induces apoptosis of Fas-expressing activated T cells. To protect the transduced APCs from self-destruction by FasL, we transferred cDNA for a truncated form of Fas-associated death domain, which inhibits Fas-mediated cell death. Our results show that the engineered APCs effectively expressed the genes of interest. APCs transduced with VVV carrying all three gene constructs specifically killed HA-transgenic T cells in culture. Coculture with T cells specific for an unrelated Ag (OVA) had no significant effect. Our in vitro findings show that APCs can be genetically engineered to target and kill Ag-specific T cells and represent a promising novel strategy for the specific treatment of autoimmune diseases.

Specific immunotherapy of experimental myasthenia gravis in vitro: the "guided missile" strategy

We describe a strategy for specific immunotherapy of myasthenia gravis (MG) based on genetic engineering of antigen presenting cells (APCs) to present the autoantigen acetylcholine receptor (AChR) and express the "warhead" Fas ligand (FasL). For transduction of APCs we prepared recombinant attenuated vaccinia virus vectors carrying the following three gene constructs: (i) AChR fused to LAMP1 to present AChR and target AChR-specific T cells; (ii) FasL to eliminate the targeted T cells; and (iii) truncated FADD to protect APCs from self-destruction by FasL. The engineered APCs effectively expressed the genes of interest and killed AChR-specific T cells in culture by the Fas/FasL pathway. T cells specific for an unrelated antigen were spared. Our in vitro demonstration that engineered APCs target and kill antigen-specific T cells represents a promising novel strategy for specific immunotherapy of MG and other autoimmune diseases.

Three-dimensional mapping of norepinephrine and serotonin in human thalamus

Detailed quantitative information on catecholamines and 5-hydroxytryptamine (serotonin) in the human thalamus is much needed because of increasing interest in norepinephrine and serotonin as modulators of thalamic behavioral state control and overall information processing. This study provides three-dimensional distribution patterns of these monoamines in postmortem thalami from 13 normal subjects (no known neurological or psychiatric histories). The patterns come from a relatively fine-grained grid mapping procedure on successive coronal sections. Samples were analyzed by high performance liquid chromatography with electrochemical detection. The highest endogenous concentrations of norepinephrine are found in a ventromedial core that includes a number of the medial and intralaminar sub-nuclei but extends only slightly into the sensory regions of the lateral tier. The posterior portion of the thalamus, the pulvinar, contains low levels of norepinephrine. The distribution of 5-hydroxytryptamine is quite similar to that of norepinephrine in the rostral two-thirds of thalamus; however, in the pulvinar region, levels of serotonin are considerably increased and differ markedly between individual thalami. The study provides the first definitive mapping of serotonin levels in human thalamus. Consistent with many animal studies, there is no evidence for major dopaminergic innervation of human thalamus. By emphasizing the pattern distribution of the monoamines rather than the absolute values, it can be shown that the ambiguities of postmortem degradation frequently associated with biochemical assays are largely avoided. The terminal field distribution of norepinephrine is an essentially constant neurochemical signature in all thalami examined. The utility of the biochemical grid mapping procedure may be especially significant in terms of matching with data from functional neuroimaging techniques.

Oral tolerance in myasthenia gravis

Because of the antibody-mediated pathogenesis of MG, it is of particular interest to understand the effects of oral administration of the autoantigen AChR on the disease process. It is now clear that feeding AChR prior to immunization can prevent clinical manifestation of EAMG. It initially primed, then inhibited, antibody responses to foreign (Torpedo) AChR and self (rat) AChR, with a delayed onset. Cellular responses to AChR, evaluated by lymphocyte proliferation and IL-2 production, were markedly inhibited. The effects were dependent on the dose and purity of the fed antigen. Tolerance to an orally administered unrelated antigen, OVA, was more prompt in development and more profound, illustrating the influence of the nature of the antigen on tolerance. The tolerance induced was antigen specific. Oral administration of AChR after immunization resulted in inhibition of the clinical manifestation of EAMG, concomitant with a paradoxical enhancement of the AChR-antibody responses. Both the clinical benefit and the antibody response appear to be dependent on the feeding protocol. These findings suggest that a molecule with less immunogenic potential than native AChR may be required for safe and effective oral treatment of ongoing disease.

Cholinergic stimulation of skeletal muscle cells induces rapid immediate early gene expression: role of intracellular calcium

Many properties of skeletal muscle are closely regulated by motor nerves. We have shown that nerve stimulation in vivo induced a rapid rise in mRNA for the immediate early gene (IEG) zif268 in stimulated muscle. However, the mechanisms leading to neural regulation of zif268 gene expression in muscle are not yet known. In this study, we used a mammalian skeletal muscle cell line (C2C12) to analyze the role of cholinergic transmission, and calcium flux, in the neural regulation of zif268. Treatment of the C2C12 muscle cells with carbachol, a cholinergic agonist, induced zif268 gene expression rapidly and transiently. This effect was blocked by alpha-bungarotoxin (alpha-BuTx), which specifically blocks nicotinic acetylcholine receptors. Treatment with ryanodine or dantrolene, which block the calcium release channel of the sarcoplasmic reticulum, inhibited the carbachol-induced zif268 response essentially completely. Calcium influx produced by A23187, a calcium ionophore, induced an increase of zif268 gene expression equivalent to the effect of carbachol stimulation. These results suggest that the effect of neural stimulation on zif268 may be attributable to cholinergic transmission, and the subsequent release of calcium from the sarcoplasmic reticulum.

In vivo dynamics of norepinephrine release-reuptake in multiple terminal field regions of rat brain

Electrical stimulation of the ascending dorsal tegmental bundle of the locus ceruleus was used to elicit controlled release of norepinephrine. Real-time in vivo monitoring in the brains of urethane-anesthetized rats was observed with high speed chronocoulometry at rapidly responding carbon fiber electrodes. Using modeling similar to that developed for dopamine release, the electrochemical signals were characterized as the balance between norepinephrine release per electrical stimulation pulse and apparent Michaelis-Menten reuptake parameters. Stimulation produced simultaneous overflow release at all terminal fields examined. The release and reuptake characteristics varied considerably in different regions. If the parameters are normalized to endogenous concentration in the terminal fields, release but not reuptake correlates with innervation density in several regions. Stimulated release results in norepinephrine overflow and transport in most brain regions with half-lives of 1-3 s and overflow distances of 25-50 microns at most. A surprising exception occurs in the upper layers of cortex (cingulate and sensory) where half-lives may be in the 10s of seconds and spatial reach may be up to 100 microns. The uptake in the outer cortical layers appears to be minimal and comparable with only nonspecific reuptake.

Comparison of the effects of voltage-sensitive calcium channel antagonism on the electrically stimulated release of dopamine and norepinephrine in vivo

IN vivo electrochemistry was used to monitor the effects of several voltage-sensitive calcium channel (VSCC) antagonists (e.g. divalent metal ions, diltiazem and omega-conotoxin GVIA (omega-CT) on the electrically evoked release of dopamine (DA) in the striatum and norepinephrine (NE) in the thalamus of the anesthetized rat. The results suggest that the N-type voltage-sensitive calcium channel is the primary VSCC involved in the electrically stimulated release of DA in the striatum, whereas stimulated release of NE in the thalamus was only partially dependent on N-type VSCC. In addition, DA release appears to be more sensitive to VSCC antagonism than does NE release with the in vivo application used in this study.

Real-time monitoring of electrically stimulated norepinephrine release in rat thalamus: I. Resolution of transmitter and metabolite signal components

Electrical stimulation of an ascending path of the locus ceruleus-norepinephrine system was used to elicit release of norepinephrine at noradrenergic terminal fields of the rat thalamus. Overflow into the extracellular fluid space was measured by fast in vivo chronoamperometry. At pretreated carbon fibers, the electrochemical signal consists of a sharp peak of approximately 20-30 s duration followed by a slower, plateau-like decay to baseline. The peak, characterized by a variety of pharmacological manipulations and dialysis perfusion, is primarily due to norepinephrine. The plateau was shown to correspond to metabolite efflux of 3,4-dihydroxy-phenylacetic acid. By varying the degree of electrochemical pretreatment, the response time and sensitivity of the fibers can be tuned to follow the entire signal or to select the separate components for detailed evaluation. This approach can be used to provide new information on the spatial and temporal characteristics of stimulated neurotransmitter release.

Real-time monitoring of electrically stimulated norepinephrine release in rat thalamus: II. Modeling of release and reuptake characteristics of stimulated norepinephrine overflow

As in the preceding study, electrical stimulation was used to effect release overflow of norepinephrine in the rat thalamus. Using a weak electrochemical pretreatment of a carbon fiber electrode, it was possible to "tune in" the electrochemical response signal for norepinephrine without metabolite interference. This reasonably selective signal was then used to study the degradation of norepinephrine release ability caused by prolonged stimulation. Further, the signals were modeled by the method used successfully for stimulated dopamine overflow, providing hitherto unavailable information on the temporal and spatial characteristics of norepinephrine release overflow. Pertinent comparisons between the release characteristics of the dopamine and norepinephrine systems show that the half-life for norepinephrine in the extracellular fluid space is approximately 1 s in thalamus compared with 33 ms for dopamine in caudate.

Neuroleptic treatment is an unlikely cause of elevated dopamine in thalamus of schizophrenic subjects

Previous studies have indicated a marked increase in the dopamine/norepinephrine ratio in thalami of schizophrenic patients compared with those of control subjects. Since these results all came from patients who were receiving neuroleptic drugs, the possibility exists that the increased dopamine concentrations are an effect of medication. To address this question, similar analyses were done on thalami from Huntington's Disease patients who had received neuroleptic treatment. The results showed no differences between the thalami of Huntington's Disease patients and controls, strongly suggesting that chronic treatment with neuroleptic drugs does not result in an increase of endogenous dopamine in the thalami of human subjects.

Intracerebral infusion of DOPAC decreases striatal dopamine

The purpose of this study was to determine whether elevated levels of 3,4-dihydroxyphenylacetic acid (DOPAC), the major metabolite of dopamine (DA) in the brain, could decrease the DA content in the striatum. Levels of DA were determined by high pressure liquid chromatography with electrochemical detection (HPLC-EC) in the striatum of male rats 24 h following a single intracerebral administration of DOPAC into the right striatum. DOPAC at 16.8 micrograms reduced the DA content of the infused side by 17%, p = 0.01. In contrast, infusion of 1.68 micrograms of DOPAC or the vehicle had no effect on striatal DA levels. Coapplication of the antioxidant, ascorbic acid, at 0.2 mg/ml with 16.8 micrograms of DOPAC prevented the decrease in DA content. Furthermore, infusion of 18.2 micrograms of homovanillic acid (HVA), the product of DOPAC methylation, had no effect on striatal DA. These results indicate that DOPAC may undergo autoxidation in vivo to produce neurotoxic species which may result in reduction of striatal DA. Formation of such an autoxidation product(s) of endogenous DOPAC was verified in the extracellular fluid of striatal slices in vitro.

Electrochemical monitoring of brain ascorbic acid changes associated with hypoxia, spreading depression, and seizure activity

In vivo electrochemistry has been a valuable tool in detecting real time neurochemical changes in extracellular fluid. Absolute selectivity has been difficult to achieve previously, but we report here a carbon fiber electrode and measurement technique which is specific for one oxidizable species: ascorbic acid. Ascorbic acid is highly concentrated in extra- as well as intracellular brain spaces, and appears to undergo dynamic changes in response to a variety of physiological and pathophysiological circumstances. Recent studies have implicated glutamatergic mechanisms which give rise to extracellular changes in brain ascorbate, and we confirm and extend these observations. Preliminary studies, directed towards examining ascorbic acid as an index and/or result of hypoxia, spreading depression, and seizure activity, have been undertaken and the results are reported herein.