Rejuvenation of cerebromicrovascular function in aged mice through heterochronic parabiosis: insights into neurovascular coupling and the impact of young blood factors

Age-related impairment of neurovascular coupling (NVC; "functional hyperemia") is a critical factor in the development of vascular cognitive impairment (VCI). Recent geroscience research indicates that cell-autonomous mechanisms alone cannot explain all aspects of neurovascular aging. Circulating factors derived from other organs, including pro-geronic factors (increased with age and detrimental to vascular homeostasis) and anti-geronic factors (preventing cellular aging phenotypes and declining with age), are thought to orchestrate cellular aging processes. This study aimed to investigate the influence of age-related changes in circulating factors on neurovascular aging. Heterochronic parabiosis was utilized to assess how exposure to young or old systemic environments could modulate neurovascular aging. Results demonstrated a significant decline in NVC responses in aged mice subjected to isochronic parabiosis (20-month-old C57BL/6 mice [A-(A)]; 6 weeks of parabiosis) when compared to young isochronic parabionts (6-month-old, [Y-(Y)]). However, exposure to young blood from parabionts significantly improved NVC in aged heterochronic parabionts [A-(Y)]. Conversely, young mice exposed to old blood from aged parabionts exhibited impaired NVC responses [Y-(A)]. In conclusion, even a brief exposure to a youthful humoral environment can mitigate neurovascular aging phenotypes, rejuvenating NVC responses. Conversely, short-term exposure to an aged humoral milieu in young mice accelerates the acquisition of neurovascular aging traits. These findings highlight the plasticity of neurovascular aging and suggest the presence of circulating anti-geronic factors capable of rejuvenating the aging cerebral microcirculation. Further research is needed to explore whether young blood factors can extend their rejuvenating effects to address other age-related cerebromicrovascular pathologies, such as blood-brain barrier integrity.

Endothelial deficiency of insulin-like growth factor-1 receptor leads to blood-brain barrier disruption and accelerated endothelial senescence in mice, mimicking aspects of the brain aging phenotype

INTRODUCTION

Age-related blood-brain barrier (BBB) disruption, cerebromicrovascular senescence, and microvascular rarefaction substantially contribute to the pathogenesis of vascular cognitive impairment (VCI) and Alzheimer's disease (AD). Previous studies established a causal link between age-related decline in circulating levels of insulin-like growth factor-1 (IGF-1), cerebromicrovascular dysfunction, and cognitive decline. The aim of our study was to determine the effect of IGF-1 signaling on senescence, BBB permeability, and vascular density in middle-age and old brains.

METHODS

Accelerated endothelial senescence was assessed in senescence reporter mice (VE-Cadherin-CreERT2 /Igf1rfl/fl × p16-3MR) using flow cytometry. To determine the functional consequences of impaired IGF-1 input to cerebromicrovascular endothelial cells, BBB integrity and capillary density were studied in mice with endothelium-specific knockout of IGF1R (VE-Cadherin-CreERT2 /Igf1rfl/fl ) using intravital two-photon microscopy.

RESULTS

In VE-Cadherin-CreERT2 /Igf1rfl/fl mice: (1) there was an increased presence of senescent endothelial cells; (2) cumulative permeability of the microvessels to fluorescent tracers of different molecular weights (0.3-40 kDa) is significantly increased, as compared to that of control mice, whereas decline in cortical capillary density does not reach statistical significance.

CONCLUSIONS

These findings support the notion that IGF-1 signaling plays a crucial role in preserving a youthful cerebromicrovascular endothelial phenotype and maintaining the integrity of the BBB.

Preventing spontaneous cerebral microhemorrhages in aging mice: a novel approach targeting cellular senescence with ABT263/navitoclax

Emerging evidence from both clinical and preclinical studies underscores the role of aging in potentiating the detrimental effects of hypertension on cerebral microhemorrhages (CMHs, or cerebral microbleeds). CMHs progressively impair neuronal function and contribute to the development of vascular cognitive impairment and dementia. There is growing evidence showing accumulation of senescent cells within the cerebral microvasculature during aging, which detrimentally affects cerebromicrovascular function and overall brain health. We postulated that this build-up of senescent cells renders the aged cerebral microvasculature more vulnerable, and consequently, more susceptible to CMHs. To investigate the role of cellular senescence in CMHs' pathogenesis, we subjected aged mice, both with and without pre-treatment with the senolytic agent ABT263/Navitoclax, and young control mice to hypertension via angiotensin-II and L-NAME administration. The aged cohort exhibited a markedly earlier onset, heightened incidence, and exacerbated neurological consequences of CMHs compared to their younger counterparts. This was evidenced through neurological examinations, gait analysis, and histological assessments of CMHs in brain sections. Notably, the senolytic pre-treatment wielded considerable cerebromicrovascular protection, effectively delaying the onset, mitigating the incidence, and diminishing the severity of CMHs. These findings hint at the potential of senolytic interventions as a viable therapeutic avenue to preempt or alleviate the consequences of CMHs linked to aging, by counteracting the deleterious effects of senescence on brain microvasculature.

Exposome and unhealthy aging: environmental drivers from air pollution to occupational exposures

The aging population worldwide is facing a significant increase in age-related non-communicable diseases, including cardiovascular and brain pathologies. This comprehensive review paper delves into the impact of the exposome, which encompasses the totality of environmental exposures, on unhealthy aging. It explores how environmental factors contribute to the acceleration of aging processes, increase biological age, and facilitate the development and progression of a wide range of age-associated diseases. The impact of environmental factors on cognitive health and the development of chronic age-related diseases affecting the cardiovascular system and central nervous system is discussed, with a specific focus on Alzheimer's disease, Parkinson's disease, stroke, small vessel disease, and vascular cognitive impairment (VCI). Aging is a major risk factor for these diseases. Their pathogenesis involves cellular and molecular mechanisms of aging such as increased oxidative stress, impaired mitochondrial function, DNA damage, and inflammation and is influenced by environmental factors. Environmental toxicants, including ambient particulate matter, pesticides, heavy metals, and organic solvents, have been identified as significant contributors to cardiovascular and brain aging disorders. These toxicants can inflict both macro- and microvascular damage and many of them can also cross the blood-brain barrier, inducing neurotoxic effects, neuroinflammation, and neuronal dysfunction. In conclusion, environmental factors play a critical role in modulating cardiovascular and brain aging. A deeper understanding of how environmental toxicants exacerbate aging processes and contribute to the pathogenesis of neurodegenerative diseases, VCI, and dementia is crucial for the development of preventive strategies and interventions to promote cardiovascular, cerebrovascular, and brain health. By mitigating exposure to harmful environmental factors and promoting healthy aging, we can strive to reduce the burden of age-related cardiovascular and brain pathologies in the aging population.

Imaging the time course, morphology, neuronal tissue compression, and resolution of cerebral microhemorrhages in mice using intravital two-photon microscopy: insights into arteriolar, capillary, and venular origin

Cerebral microhemorrhages (CMHs, microbleeds), a manifestation of age-related cerebral small vessel disease, contribute to the pathogenesis of cognitive decline and dementia in older adults. Histological studies have revealed that CMHs exhibit distinct morphologies, which may be attributed to differences in intravascular pressure and the size of the vessels of origin. Our study aimed to establish a direct relationship between the size/morphology of CMHs and the size/anatomy of the microvessel of origin. To achieve this goal, we adapted and optimized intravital two-photon microscopy-based imaging methods to monitor the development of CMHs in mice equipped with a chronic cranial window upon high-energy laser light-induced photodisruption of a targeted cortical arteriole, capillary, or venule. We assessed the time course of extravasation of fluorescently labeled blood and determined the morphology and size/volume of the induced CMHs. Our findings reveal striking similarities between the bleed morphologies observed in hypertension-induced CMHs in models of aging and those originating from different targeted vessels via multiphoton laser ablation. Arteriolar bleeds, which are larger (> 100 μm) and more widely dispersed, are distinguished from venular bleeds, which are smaller and exhibit a distinct diffuse morphology. Capillary bleeds are circular and smaller (< 10 μm) in size. Our study supports the concept that CMHs can occur at any location in the vascular tree, and that each type of vessel produces microbleeds with a distinct morphology. Development of CMHs resulted in immediate constriction of capillaries, likely due to pericyte activation and constriction of precapillary arterioles. Additionally, tissue displacement observed in association with arteriolar CMHs suggests that they can affect an area with a radius of ~ 50 μm to ~ 100 μm, creating an area at risk for ischemia. Longitudinal imaging of CMHs allowed us to visualize reactive astrocytosis and bleed resolution during a 30-day period. Our study provides new insights into the development and morphology of CMHs, highlighting the potential clinical implications of differentiating between the types of vessels involved in the pathogenesis of CMHs. This information may help in the development of targeted interventions aimed at reducing the risk of cerebral small vessel disease-related cognitive decline and dementia in older adults.

Imaging retinal microvascular manifestations of carotid artery disease in older adults: from diagnosis of ocular complications to understanding microvascular contributions to cognitive impairment

Carotid artery stenosis (CAS) is a consequence of systemic atherosclerotic disease affecting the aging populations of the Western world. CAS is frequently associated with cognitive impairment. However, the mechanisms contributing to the development of vascular cognitive impairment (VCI) associated with CAS are multifaceted and not fully understood. In addition to embolization and decreased blood flow due to the atherosclerotic lesion in the carotid artery, microcirculatory dysfunction in the cerebral circulation also plays a critical role in CAS-related VCI. To better understand the microvascular contributions to cognitive decline associated with CAS and evaluate microvascular protective effects of therapeutic interventions, it is essential to examine the structural and functional changes of the microvessels in the central nervous system (CNS). However, there are some limitations of in vivo brain vascular imaging modalities. The retinal microvasculature provides a unique opportunity to study pathogenesis of cerebral small vessel disease and VCI, because the cerebral circulation and the retinal circulation share similar anatomy, physiology and embryology. Similar microvascular pathologies may manifest in the brain and the retina, thus ocular examination can be used as a noninvasive screening tool to investigate pathological changes in the CNS associated with CAS. In this review, ocular signs of CAS and the retinal manifestations of CAS-associated microvascular dysfunction are discussed. The advantages and limitation of methods that are capable of imaging the ocular circulation (including funduscopy, fluorescein angiography, Doppler sonography, optical coherence tomography [OCT] and optical coherence tomography angiography [OCTA]) are discussed. The potential use of dynamic retinal vessel analysis (DVA), which allows for direct visualization of neurovascular coupling responses in the CNS, for understanding microvascular contributions to cognitive decline in CAS patients is also considered.

Retinal biomarkers for Alzheimer's disease and vascular cognitive impairment and dementia (VCID): implication for early diagnosis and prognosis

Cognitive impairment and dementia are major medical, social, and economic public health issues worldwide with significant implications for life quality in older adults. The leading causes are Alzheimer's disease (AD) and vascular cognitive impairment/dementia (VCID). In both conditions, pathological alterations of the cerebral microcirculation play a critical pathogenic role. Currently, the main pathological biomarkers of AD-β-amyloid peptide and hyperphosphorylated tau proteins-are detected either through cerebrospinal fluid (CSF) or PET examination. Nevertheless, given that they are invasive and expensive procedures, their availability is limited. Being part of the central nervous system, the retina offers a unique and easy method to study both neurodegenerative disorders and cerebral small vessel diseases in vivo. Over the past few decades, a number of novel approaches in retinal imaging have been developed that may allow physicians and researchers to gain insights into the genesis and progression of cerebromicrovascular pathologies. Optical coherence tomography (OCT), OCT angiography, fundus photography, and dynamic vessel analyzer (DVA) are new imaging methods providing quantitative assessment of retinal structural and vascular indicators-such as thickness of the inner retinal layers, retinal vessel density, foveal avascular zone area, tortuosity and fractal dimension of retinal vessels, and microvascular dysfunction-for cognitive impairment and dementia. Should further studies need to be conducted, these retinal alterations may prove to be useful biomarkers for screening and monitoring dementia progression in clinical routine. In this review, we seek to highlight recent findings and current knowledge regarding the application of retinal biomarkers in dementia assessment.

Microvascular contributions to age-related macular degeneration (AMD): from mechanisms of choriocapillaris aging to novel interventions

Aging of the microcirculatory network plays a central role in the pathogenesis of a wide range of age-related diseases, from heart failure to Alzheimer's disease. In the eye, changes in the choroid and choroidal microcirculation (choriocapillaris) also occur with age, and these changes can play a critical role in the pathogenesis of age-related macular degeneration (AMD). In order to develop novel treatments for amelioration of choriocapillaris aging and prevention of AMD, it is essential to understand the cellular and functional changes that occur in the choroid and choriocapillaris during aging. In this review, recent advances in in vivo analysis of choroidal structure and function in AMD patients and patients at risk for AMD are discussed. The pathophysiological roles of fundamental cellular and molecular mechanisms of aging including oxidative stress, mitochondrial dysfunction, and impaired resistance to molecular stressors in the choriocapillaris are also considered in terms of their contribution to the pathogenesis of AMD. The pathogenic roles of cardiovascular risk factors that exacerbate microvascular aging processes, such as smoking, hypertension, and obesity as they relate to AMD and choroid and choriocapillaris changes in patients with these cardiovascular risk factors, are also discussed. Finally, future directions and opportunities to develop novel interventions to prevent/delay AMD by targeting fundamental cellular and molecular aging processes are presented.

Age-related impairment of neurovascular coupling responses: a dynamic vessel analysis (DVA)-based approach to measure decreased flicker light stimulus-induced retinal arteriolar dilation in healthy older adults

Aging is a major risk factor for vascular cognitive impairment and dementia (VCID). Recent studies demonstrate that cerebromicrovascular dysfunction plays a causal role in the development of age-related cognitive impairment, in part via disruption of neurovascular coupling (NVC) responses. NVC (functional hyperemia) is responsible for adjusting cerebral blood flow to the increased energetic demands of activated neurons, and in preclinical animal models of aging, pharmacological restoration of NVC is associated with improved cognitive performance. To translate these findings, there is an increasing need to develop novel and sensitive tools to assess cerebromicrovascular function and NVC to assess risk for VCID and evaluate treatment efficacy. Due to shared developmental origins, anatomical features, and physiology, assessment of retinal vessel function may serve as an important surrogate outcome measure to study neurovascular dysfunction. The present study was designed to compare NVC responses in young (< 45 years of age; n = 18) and aged (> 65 years of age; n = 11) healthy human subjects by assessing flicker light-induced changes in the diameter of retinal arterioles using a dynamic vessel analyzer (DVA)-based approach. We found that NVC responses in retinal arterioles were significantly decreased in older adults as compared with younger subjects. We propose that the DVA-based approach can be used to assess NVC, as a surrogate cerebromicrovascular outcome measure, to evaluate the effects of therapeutic interventions in older individuals.

Abstract P1-02-09: Targeting breast cancer stem cell state equilibrium through modulation of redox signaling

Breast cancer stem cells (BCSCs) maintain the plasticity to transition between quiescent mesenchymal- (M) and proliferative epithelial-like (E) states, but how this plasticity is regulated under metabolic/oxidative stress is poorly understood. Here, we show that M- and E-BCSCs exhibit markedly different sensitivities to the inhibitors of glycolysis and redox metabolism. Metabolic/Oxidative stress generated by 2DG/H2O2 or hypoxia promotes ROSlo M-BCSCs transition to their ROShi E-state. This transition is reversed by the antioxidant N-acetyl cysteine and facilitated by the activation of the AMPK-HIF1α axis. Moreover, E-BCSCs exhibit robust expression of NRF2/NFE2L2 and a wide variety of NRF2 downstream antioxidant responsive genes including the family of drug transporters and detoxification enzymes, NADPH production as well as the thioredoxin (TXN) and glutathione (GSH) antioxidant pathways. Suppression of NRF2 activity by a small-molecular inhibitor Trigonelline or shNRF2 mediated knockdown significantly decreased ALDH+ E- but not CD24-CD44+ M-BCSCs. This specific vulnerability of E-BCSCs to the inhibition of NRF2-mediated antioxidant defenses was also observed following inhibition of the downstream TXN and GSH antioxidant pathways, which promotes ROS-mediated differentiation and subsequent apoptosis of E-BCSCs. Co-inhibition of glycolysis and TXN/GSH pathways synergistically suppressed tumor growth and tumor initiating potential in two patient-derived xenograft models of triple negative breast cancer by eliminating both M- and E-BCSCs. Together, our studies reveal novel cellular and molecular mechanisms demonstrating how modulation of redox signaling regulates the equilibrium of two distinct BCSC states. These studies define the metabolic vulnerabilities of M- and E-BCSCs, and also provide a novel therapeutic approach to collectively target these distinct CSC states. As the CSC state equilibrium may be similarly regulated across a spectrum of tumors with diverse oncogenic drivers, this approach may have broad therapeutic applicability.

Citation Format: Luo M, Shang L, Brooks M, Jiagge E, Zhu Y, Conley S, Fath MA, Harouaka R, Merajver SD, Spitz DR, Wicha MS. Targeting breast cancer stem cell state equilibrium through modulation of redox signaling [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P1-02-09.

Nanoparticle applications in ocular gene therapy

The use of nanoparticles as carriers for the delivery of therapeutic materials to target tissues has became popular in recent years and has demonstrated great potentials for the treatments of a wide range of diseases. In this review, we summarize the advantages of nanotechnology as a common gene delivery strategy with emphasis on ocular therapy. Particular attention is paid to the CK30-PEG compacted DNA nanoparticles that have been successfully tested in the eye, lung, and brain. These particles resulted in higher transfection efficiency and longer duration of expression than other non-viral vectors without any toxicity or other side effects. They have been safely used clinically and are efficient for a broad range of gene therapy applications. The review also discusses mechanisms of nanoparticle uptake and internalization by cells, obstacles and limitations to the use of this technology, as well as novel methodologies to optimize nanoparticle driven gene expression.

Late-onset cone photoreceptor degeneration induced by R172W mutation in Rds and partial rescue by gene supplementation

PURPOSE

R172W is a common mutation in the human retinal degeneration slow (RDS) gene, associated with a late-onset dominant macular dystrophy. In this study, the authors characterized a mouse model that closely mimics the human phenotype and tested the feasibility of gene supplementation as a disease treatment strategy.

METHODS

Transgenic mouse lines carrying the R172W mutation were generated. The retinal phenotype associated with this mutation in a low-expresser line (L-R172W) was examined, both structurally (histology with correlative immunohistochemistry) and functionally (electroretinography). By examining animals over time and with various rds genetic backgrounds, the authors evaluated the dominance of the defect. To assess the efficacy of gene transfer therapy as a treatment for this defect, a previously characterized transgenic line expressing the normal mouse peripherin/Rds (NMP) was crossed with a higher-expresser Rds line harboring the R172W mutation (H-R172W). Functional, structural, and biochemical analyses were used to assess rescue of the retinal disease phenotype.

RESULTS

In the wild-type (WT) background, L-R172W mice exhibited late-onset (12-month) dominant cone degeneration without any apparent effect on rods. The degeneration was slightly accelerated (9 months) in the rds(+/-) background. L-R172W retinas did not form outer segments in the absence of endogenous Rds. With use of the H-R172W line on an rds(+/-) background for proof-of-principle genetic supplementation studies, the NMP transgene product rescued rod and cone functional defects and supported outer segment integrity up to 3 months of age, but the rescue effect did not persist in older (11-month) animals.

CONCLUSIONS

The R172W mutation leads to dominant cone degeneration in the mouse model, regardless of the expression level of the transgene. In contrast, effects of the mutation on rods are dose dependent, underscoring the usefulness of the L-R172W line as a faithful model of the human phenotype. This model may prove helpful in future studies on the mechanisms of cone degeneration and for elucidating the different roles of Rds in rods and cones. This study provides evidence that Rds genetic supplementation can be used to partially rescue visual function. Although this strategy is capable of rescuing haploinsufficiency, it does not rescue the long-term degeneration associated with a gain-of-function mutation.

Successful transplantation of adult-sized kidneys into infants requires maintenance of high aortic blood flow

BACKGROUND

Nationally, results of renal transplantation in infants are inferior to those in older children and adults. Within the infant group, best results are obtained with adult-sized kidneys (ASKs) rather than size-compatible pediatric kidneys. However, transplantation of ASKs into infants has an increased risk of acute tubular necrosis and graft loss from vascular thrombosis and primary nonfunction. The aim of this study was to define and understand the hemodynamic changes induced by ASK transplantation, so that outcomes of transplantation in infants can be improved.

METHODS

Nine hemodynamically stable and optimally hydrated infants were studied under a controlled sedation with cine phase-contrast magnetic resonance at three time periods: before transplantation, 8-12 days after transplantation, and 4-6 months after transplantation. Cross-sectional images of both the infant aorta and the adult transplant renal artery were obtained and blood flow was quantitated. Renal volumes were also obtained, and expected renal artery blood flow based on early posttransplant volume was calculated. In addition, renal artery blood flow was determined in 10 in situ native adult kidneys prior to donor nephrectomy. Supplemental nasogastric or gastrostomy tube feeding was carried out during the blood flow study period to optimize intravascular volume.

RESULTS

Mean infant aortic blood flows were 331+/-148 ml/min before transplantation, 761+/-272 ml/ min at 8-12 days after transplantation (P=0.0006 with pretransplant flow), and 665+/-138 ml/min at 4-6 months after transplantation (P=0.0001 with pretransplant flow). Mean transplanted renal artery flows were 385+/-158 ml/min at 8-12 days and 296+/-113 ml/min at 4-6 months after transplantation. Transplanted renal artery flows were less than prenephrectomy in situ donor renal artery blood flow (618+/-130 ml/min; P=0.02 and P=0.0003) and expected normal renal artery blood flow (666+/-87 ml/min; P=0.003 and P=0.001) at both 8-12 days and 4-6 months after transplantation. A 26% reduction in renal volume (P=0.003) occurred between the two postoperative time periods, and this paralleled the decrease in posttransplant renal artery flow. One-year graft and patient survival in the nine infants was 100%. The mean serum creatinine levels at 3, 6, and 12 months were 0.43+/-0.10, 0.48+/-0.15, and 0.49+/-0.16 mg/dl.

CONCLUSIONS

This study is the first to quantitatively document the blood flow changes occurring after ASK transplantation in infants. There was a greater than two-fold increase in aortic blood flow after ASK transplantation, and this increase was sustained for at least 4 months and appeared to be driven by the blood flow demand of the ASK. However, actual posttransplant renal artery blood flow was significantly less than normal renal artery flow. Our study suggests that aggressive intravascular volume maintenance may be necessary to achieve and maintain optimum aortic blood flow, so as not to further compromise posttransplant renal artery flow and to avoid low-flow states that could induce acute tubular necrosis, vascular thrombosis, or primary nonfunction.

The invariant chain gene intronic enhancer shows homology to class II promoter elements

Coordinate expression of MHC class II proteins and the class II-associated invariant chain (Ii) is important for proper MHC class II functioning in Ag processing and presentation. The coordinate regulation of these genes results, in part, from the sharing of transcriptional regulatory regions between MHC class II and Ii genes; the Ii has previously been shown to have an upstream enhancer closely related to the essential class II promoter elements. We report here the characterization of a second enhancer in the Ii gene, located within the first intron. This intronic enhancer is contained within a 155-bp region, enhances transcription from the Ii minimal promoter, and also contains elements that are homologous to class II promoter elements X1, X2, and Y boxes.

Preliminary findings of an in vitro human spleen mononuclear cell culture system for primary isolates of HIV type 1

Acute HIV-1 infection is often manifested with a high level of viremia. The cell types and tissues/organs that contribute to the virus load are thought to be of central and peripheral lymphoreticular origin. The establishment and permissiveness of organ-based cell culture systems from spleen with laboratory strains or primary isolates of HIV-1 have not been reported. We studied unseparated splenic mononuclear cells (SMCs) and adherent cells derived from human spleen and liver in comparison with blood monocyte-derived macrophages (MDMs). Unstimulated, SMCs were highly permissive to primary lymphotropic HIV-1 and dual/macrophage-tropic isolates (which are able to replicate in both MDMs and PBMCs). Furthermore, SMCs were found to replicate virus to high titer in a rapid log-phase manner and exhibited a prolonged stationary phase of virus production, unlike PBMCs, which required conventional activation with mitogens and exhibited a much shorter period of virus production. Interestingly, the SMCs maintained themselves as a mixed phenotype of nested lymphocytes with complex and well-differentiated macrophage(s) for extended periods of time. In addition, splenic macrophages readily purified by adherence were highly permissive to a dual/macrophage-tropic primary isolate, HIV-1ADA, intermediate with two laboratory strains, HIVR-1RF and HIV-lHXB3, and least permissive to the lymphotropic primary isolate HIV-1Mr452 and two other laboratory strains, HIV-1CC and HIV-1MN. The replication of HIV-1ADA as measured by extracellular p24 was sustained for up to 7 weeks and similar to the replication patterns observed with adherent hepatic macrophages and blood-derived MDMs. This study demonstrates that exogenous stimulation is not required for infection of these cells; either adherence-isolated and/or mixed lymphoid populations can be studied together, and viable stocks can be readily prepared and cryopreserved. In addition, these cells could be used for isolating new and/or other variants of HIV-1. Thus, the use of the SMC primary in vitro cell culture system for future studies involving HIV-1 is warranted.

Unusual laryngeal cysts in the newborn

In the newborn, severe airway obstruction is a rare occurrence. The possible etiologies include a broad spectrum of diseases with laryngeal cysts an unusual cause. If diagnosed and properly managed, however, the prognosis for this entity is excellent. Three cases presenting with airway obstruction secondary to unusual laryngeal cysts are the material for this report. In all three, cases the laryngeal cystic structure extended through the cricothyroid membrane and in two, pathologically contained both mesodermal and endodermal elements suggesting a laryngotracheal duplication cyst anomaly, previously unreported. Laryngofissure can be safely employed for complete excision even in the neonatal period.

Serial measurements of GFR in infants using the continuous iothalamate infusion technique. Southwest Pediatric Nephrology Study Group (SPNSG)

We undertook a preliminary study to determine if a clinical trial was feasible that would compare the effect of a low protein vs a control formula on GFR and growth in infants with congenital renal insufficiency (CIo < 55 ml/min/1.73 m2). In this report from the Infant Diet Protein Study, we describe validation of a method using the plasma clearance of iothalamate (CIo) as an estimate of glomerular filtration rate (GFR) and results of the preliminary study relating to renal function. The plasma CIo method was validated as an accurate estimate of GFR by showing it to be the same as the plasma clearance of inulin (CIn). In the preliminary study infants who qualified for the study were randomly assigned to a low protein or control formula and were followed from 8 to 18 months of age. CIo was measured at 8, 14 and 18 months of age in 21 of the infants and at 8 and 18 months of age in all twenty four infants that entered the study. Average absolute GFR in the 24 infants increased in the 10 month period from 5.3 +/- 2.7 to 7.6 +/- 4.5 ml/min. The percent increase in GFR was no different in infants whose GFR at 8 months of age was severely reduced from those whose GFR was only moderately reduced. When adjusted for age and body size, GFR did not change. Change in mean CIo or serum creatinine (SCr) from 8 to 18 months of age between the infants in each diet groups was not different. We conclude that a clinical trial enrolling more infants and extending the study period is necessary to evaluate dietary protein effect.

Decrease in cytokine production by HIV-infected macrophages in response to LPS-mediated activation

The capacity of human monocytes/macrophages (M/M) infected with a human immunodeficiency virus-1 (HIV-1) isolate to produce several immunomodulating cytokines including interleukin-1 alpha (IL-1 alpha), IL-1 beta, tumor necrosis factor-alpha (TNF-alpha), IL-6, IL-8, and macrophage chemoattractant and activating factor (MCAF) was examined. Although HIV infection itself induced significant increases in the level of mRNAs for IL-1 beta, TNF-alpha, IL-6, and IL-8, the levels of lipopolysaccharide (LPS)-induced mRNAs for IL-1 alpha, IL-1 beta, TNF-alpha, IL-6, IL-8, and MCAF were decreased over those of uninfected LPS-stimulated cells. In addition, HIV-infected M/M produced lower amounts of IL-8 protein, as measured by radioimmunoassay over an 18-day culture period. These results suggest that HIV infection generally suppresses the LPS-inducible cytokine production in human M/M. The impact of the role of these cytokines in the immunity and pathogenesis of HIV-1 infection is discussed.

The inability of human immunodeficiency virus to infect chimpanzee monocytes can be overcome by serial viral passage in vivo

Studies of lentivirus infection in ruminants, nonhuman primates, and humans suggest that virus infection of macrophages plays a central role in the disease process. To investigate whether human immunodeficiency virus type 1 (HIV-1) can infect chimpanzee macrophages, we recovered monocytes from peripheral blood mononuclear cells of HIV-1-negative animals and inoculated these and control human monocytes with a panel of four human-passaged monocytotropic virus strains and one chimpanzee-passaged isolate. HIV-1 infected human monocytes synthesized proviral DNA, viral mRNA, p24 antigen, and progeny virions. In contrast, except for the chimpanzee-passaged HIV-1 isolate, chimpanzee monocytes failed to support HIV-1 replication when cultured under both identical and a variety of other conditions. Proviral DNA was demonstrated only at background levels in these cell cultures by polymerase chain reaction for gag- and env-related sequences. Interestingly, the chimpanzee-passaged HIV-1 isolate did not replicate in human monocytes; viral p24 antigens and progeny virions were not detected. The same monocytotropic panel of HIV-1 strains replicated in both human and chimpanzee CD4+ T lymphoblasts treated with phytohemagglutinin and interleukin-2. The failure of HIV-1 to infect chimpanzee monocytes, which can be overcome by serial in vivo viral passage, occurs through a block early in the viral life cycle.

Evaluation of neonatal subglottic stenosis: a 3-year prospective study

Subglottic stenosis is the most common cause of chronic airway obstruction. It results in prolonged tracheal cannulation of infants and children. Following the widespread adoption over the past 20 years of prolonged intubation for respiratory support in neonates, the incidence of acquired subglottic stenosis increased dramatically. On January 1, 1987, we began a 3-year prospective study to delineate potential etiologic factors involved in the development of subglottic stenosis in neonates. The present study analyzes data from 289 infants. Relationships between birth weight, gestational age, endotracheal tube size, duration of intubation and ventilation, number and difficulty of intubations, and the subsequent need for medical and surgical therapy are discussed. Whole organ larynges from autopsy specimens provide histological correlation.

The 1989 report of the North American Pediatric Renal Transplant Cooperative Study

This report of the North American Pediatric Transplant Cooperative Study summarizes data contributed by 57 participating centers on 754 children with 761 transplants from 1 January 1989 to 16 February 1989. Data collection was initiated in October 1987 and follow-up of all patients is ongoing. Transplant frequency increased with age; 24% of the patients were less than 5 years, with 7% being under 2 years. Common frequent diagnoses were: aplastic/dysplastic kidneys (18%), obstructive uropathy (16%), and focal segmental glomerulosclerosis (12%). Preemptive transplant, i.e., transplantation without prior maintenance dialysis, was performed in 21% of the patients. Dialytic modalities pretransplant were peritoneal dialysis in 42% and hemodialysis in 25%. Bilateral nephrectomy was reported in 29%. Live-donor sources accounted for 42% of the transplants. Among cadaveric donors, 41% of the donors were under 11 years old. During the first post-transplant month, maintenance therapy was used similarly for live-donor and cadaver source transplants, with prednisone, cyclosporine, and azathioprine used in 93%, 83%, and 81%, respectively. Triple therapy with prednisone, cyclosporine, and azathioprine was used in 78%, 75%, and 75% of functioning cadaver source transplants at 6 months, 12 months, and 18 months as opposed to 60%, 63%, and 54% for live-donor procedures, with single-drug therapy being uncommon. Rehospitalization during months 1-5 occurred in 62% of the patients, with treatment of rejection and infection being the main causes. Additionally, 9% were hospitalized for hypertension. During months 6-12 and 12-17, 30% and 28% of the patients with functioning grafts were rehospitalized. Times to first rejection differed significantly for cadaver and live-donor transplants. The median time to the first rejection was 36 days for cadaver transplants and 156 days for live-donor transplants. Overall, 57% of treated rejections were completely reversible although the complete reversal rate decreased to 37% for four or more rejections. One hundred and fifty-two graft failures had occurred at the time of writing, with a 1-year graft survival estimate of 0.88 for live-donor and 0.71 for cadaver source transplants. In addition to donor source, recipient age is a significant prognostic factor for graft survival. Among cadaver donors, decreasing donor age is associated with a decreasing probability of graft survival. Thirty-five deaths have occurred; 16 attributed to infection and 19 to other causes. The current 1-year survival estimate is 0.94. There have been 9 malignancies.

Antibody-mediated in vitro neutralization of human immunodeficiency virus type 1 abolishes infectivity for chimpanzees

This study was undertaken to establish whether antibody directed against the human immunodeficiency virus type 1 (HIV-1) principal gp120 type-specific neutralization determinant can abolish the infectivity of HIV-1 in chimpanzees. Challenge inocula of the IIIb virus isolate were mixed in vitro with either immunoglobulin G (IgG) from an uninfected chimpanzee, nonneutralizing IgG from an HIV-seropositive human, a virus-neutralizing murine monoclonal antibody directed against the HIV-1 IIIb isolate, or virus-neutralizing IgG from a chimpanzee infected with the IIIb isolate. Both neutralizing antibodies were directed against the principal neutralization determinant of the challenge isolate. Establishment of infection following inoculation of each virus-antibody mixture into chimpanzees was assessed by virus-specific antibody development and by virus isolation. No protective effect was noted either with the control IgG or with the nonneutralizing anti-HIV IgG. By contrast, the polyclonal chimpanzee virus-neutralizing IgG prevented HIV-1 in vivo infection, while the neutralizing monoclonal antibody notably decreased the infectivity of the challenge virus. Hence, antibody to the gp120 principal neutralization determinant is able both to prevent HIV-1 infection in vitro and to inhibit infection in vivo.

Peripheral T-cell lymphoma

Peripheral T-cell lymphoma is the most common type of T-cell lymphoma seen in adults in the United States. Clinical data were reviewed from 134 cases of peripheral T-cell lymphoma diagnosed in three centers. The median age of the patients was 57 years (range, 4-97 years), 59% were male, and 36 patients (27%) had a history of a preceding disorder of the immune system. The tumors were grouped histologically into large cell (43%), mixed large and small cell (40%), and small cell (17%). The stage at diagnosis was I (7%), II (21%), III (22%), and IV (50%). B symptoms were present in 57%. The most frequent sites of extranodal involvement were bone marrow (35%), skin (13%), and lung (11%). Eighty patients were treated with a multiagent chemotherapy regimen with proven curative potential in aggressive non-Hodgkin's lymphomas and the remainder of the patients received less intensive chemotherapy (36 patients), radiotherapy (nine patients), or no treatment (nine patients). Fifty percent of the intensively treated patients achieved complete remission and the actuarial 4-year survival was 45%. However, the 4-year, disease-free survival in patients with Stage IV disease was only 10%. Although peripheral T-cell lymphomas appeared similar in many ways to their B-cell counterparts, disease-free survival by stage was low and patients with Stage IV disease had an especially poor outlook.

Ranulas--mucoceles of the oral cavity: experience in 26 children

Ranulas or mucoceles of the floor of the mouth are uncommon but do occur in approximately 5% of patients undergoing submandibular duct relocation for the management of uncontrollable sialorrhea. Review of our experience with 26 patients over 12 years ending in 1986 substantiated a concept previously advocated by other authors that ranulas are usually extravasation pseudocysts developing after disruption of sublingual gland elements, and that excision of the ipsilateral sublingual gland is the management approach of choice.

Parent-to-child transplantation with cyclosporine immunosuppression

The use of cyclosporine, a fungal endecapeptide immunosuppressive agent, has greatly improved the outcome of haploidentical transplantation in adults, but less impressively improved the result of parent to child transplantation. The incidence of allograft loss and treated rejection episodes was much greater in pediatric than in adult recipients, and the evidences of nephrotoxicity lessened. Although resistance of the child's immune system to the effects of the drug cannot be excluded, it appears more likely that this relates to the rapid clearance of the agent in the pediatric age group (39.6 mL/min/kg) versus in adults (12.3 mL/min/kg), thereby reducing the area under the serum concentration curve from 765 +/- 593 to 386 +/- 277 ng/mL/hr per mg/kg (mean +/- SD). This effect caused trough serum levels measured by radioimmunoassay to be below the putative threshold. These findings demonstrate the need for higher cyclosporine doses and frequency in pediatric compared with adult patients.

Myelopathy in neonatal and infantile lupus erythematosus

Two children with lupus erythematosus and myelopathy were studied. The first child developed the neonatal lupus erythematosus syndrome associated with transplacentally acquired anti-Ro/SSA antibodies. The cutaneous manifestations of neonatal lupus erythematosus disappeared but a residual myelopathy was confirmed at 16 months of age. The second child developed cutaneous lupus erythematosus at 3 months of age associated with a total deficiency of the Clr component of complement. A myelopathy and mesangial glomerulonephritis developed at 2 years of age which required treatment with corticosteroids. These two children with CNS lupus erythematosus, one associated with transplacentally acquired antibodies and the other associated with a complement deficiency, may suggest an immune-mediated mechanism for the pathogenesis of myelopathy in childhood lupus erythematosus.

Complications of cyclosporine-prednisone immunosuppression in 402 renal allograft recipients exclusively followed at a single center for from one to five years

The therapeutic efficacy of cyclosporine (CsA) as an immunosuppressive agent was complemented by a modest, long-term incidence of toxic complications in 402 renal allograft recipients engrafted one to five years prior to analysis. The overall patient and graft survivals at one year were 97% and 84% (actual), and at five years 92% and 67% (actuarial). The immunosuppressive therapeutic index was excellent: only 12% of allografts were lost from rejection, with 5% of patients succumbing to infection. While infections were common, tending to emanate in the urinary tract or to be viral in etiology, they were generally mild and readily controlled. Only four patients displayed malignancies; none succumbed to this cause. The most common toxic complication was hypertrichosis, which was accentuated in pediatric patients. While tremors occurred in 20% of patients, primarily during the first three months, other neuroectodermal complications of parethesias, depression, somnolence, and seizures were rare. Hepatotoxicity, which was noted in 50% of patients, particularly recipients of cadaveric grafts, generally was first seen as a transaminase elevation, at least partially reversible by dose-reduction and abating by the third year. Associated disturbances of cholelithiasis and pancreatitis were occasionally observed. Nephrotoxicity was the only persistent, long-term complication. Hypertension occurred in 72% of patients during the first month, 36% in the second year, and about 15% thereafter. Hyperuricemia, which occurred in about 30% of recipients during the first two years, was occasionally associated with symptomatic gout. The mean serum creatinine level remained elevated throughout the follow-up period at 1.8-1.9 mg/dl, suggesting persistent, but nonprogressive, drug-induced renal injury. The present analysis documents the relative safety of CsA for long-term therapy, and highlights the need for new approaches to ameliorate drug-induced nephrotoxicity.

The influence on pretransplant blood transfusions from random donors on immune parameters affecting cadaveric allograft survival

The number of pretransplant blood transfusions (BT) from random donors influences the recipient's immune response status and suppressor cell number and function, as well as allograft survival. The 54% one-year survival rate for 104 cadaveric renal allograft recipients treated with azathioprine and prednisone was divisible into two groups: 74.5% in 51 patients receiving greater than 5 BT and 34% for 53 patients with less than 5 BT (P less than 0.02). Transfusions enhanced the benefit of HLA A, B, and DR compatibility on graft survival: 33 recipients of well-matched grafts (less than 2 A, B, and 0-1 DR mismatches) had a one-year survival rate of 94% when pretreated with greater than 5 BT, compared with 38% when receiving less than 5 BT (P less than 0.05). The graft survival of 73% (36/49) displayed by patients determined preoperatively to be weak immune responders was significantly better than the 36% survival (20/55) demonstrated by strong immune responders (P less than 0.01). The transfusion history correlated with immune responder status: 76% (39/51) of patients receiving greater than 5 BT were weak immune responders, whereas 81% (43/53) of patients receiving less than 5 BT were strong immune responders (P less than 0.001). Ninety-two percent (12/13) of patients with greater than 5 BT, but only 58% (10/17) of patients with less than 5 BT, had a normal number of OKT8+ T suppressor cells. Only 1 X 10(5) mononuclear cells from patients with greater than 5 BT rather than 4 X 10(5) cells from patients with less than 5 BT caused 50% suppression of a third-party MLC. Thus, patients receiving greater than 5 BT are more likely to display weak immune responses, normal numbers of OKT8 cells, strong suppressor function in vitro, and prolonged allograft survival.

A regional network review of health care delivery to children and adolescents with end-stage renal disease

A detailed survey of dialysis facilities in Texas (ESRD Network No. 11) evaluated the health care delivery to all ESRD patients under 21 year of age. 38 units reported data on 115 patients (50 males, 65 females) ranging in age from 7 months to 20 years. Home peritoneal dialysis was used in 20% of the patients with the rest treated by in-center hemodialysis. 50% of the patients were active transplant candidates at the time of survey; of the remaining 58 patients, there were medical reasons for the nontransplant status of 33 but 25 patients elected to stay on dialysis in the absence of medical contraindications to transplant. The units provided excellent support for the psychosocial, educational, nutritional and growth needs of the children and adolescents surveyed.