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Lois E H Smith

Publications and source records attributed to Lois E H Smith.

At least 19 recordsLinked to original sources
PubMed2026

Proteomic Profile in Retinopathy of Prematurity: A Secondary Analysis of the Mega Donna Mega Randomized Clinical Trial.

IMPORTANCE: Identifying early proteomic profiles in infants who develop severe retinopathy of prematurity (ROP) may reveal targets for preventive interventions to reduce retinal vessel loss and the subsequent risk of severe ROP. OBJECTIVE: To assess early longitudinal profiles of blood protein levels in preterm infants with or without severe ROP and the effect of arachidonic acid (AA) and docosahexaenoic acid (DHA) supplementation. DESIGN, SETTING, AND PARTICIPANTS: This was an exploratory, post hoc analysis of serum proteome profiles in preterm infants in the double-masked Mega Donna Mega (MDM) randomized clinical trial using targeted Olink Proximity Extension Assay proteomics covering 538 analytes. The setting was 3 university hospitals in Sweden and included extremely preterm infants born before 28 weeks of gestational age (GA), from 2016 to 2019. Data were analyzed from January to March 2025. EXPOSURES: All infants received standard nutrition; additionally, half received enteral lipid supplementation with AA/DHA (100/50 mg/kg per day) from birth to term equivalent age. MAIN OUTCOMES AND MEASURES: Longitudinal protein profiles during the first month of life were examined using mixed models for repeated measures, adjusted for GA, study center, and AA/DHA supplementation, and tested for the interaction between severe ROP (stage &#x2265;3 and/or treated) and postnatal age. RESULTS: A total of 177 extremely preterm infants (mean [SD] GA, 25.6 [1.4] weeks; 100 male [56.5%]) were included, of whom 50 (28.2%) developed severe ROP. Of 538 longitudinal analyzed proteins, 109 protein profiles in the first month of life associated with severe ROP, proteins related to immune response, apoptotic processes, blood coagulation, and lipid metabolism. The most pronounced association with severe ROP was a fast rise in fibroblast growth factor 21 (FGF-21; &#x3b2;&#x2009;=&#x2009;0.68; 95% CI,&#x2009;0.39-0.97; Q =.002) and tissue plasminogen activator (tPA; &#x3b2;&#x2009;=&#x2009;0.21; 95% CI,&#x2009;0.13-0.29; Q <.001) during the first postnatal days. The increase in serum FGF-21 level in the first week of life was associated with lower GA, lower birth weight, low enteral energy intake, and more days receiving mechanical ventilation. No association was observed between AA/DHA supplementation and the proteome. CONCLUSIONS AND RELEVANCE: In this post hoc exploratory analysis of data from the MDM randomized clinical trial, a fast rise in FGF-21 levels, a metabolic stress-induced hormone, during the first postnatal days was strongly associated with the development of severe ROP in extremely preterm infants. These findings suggest that early interventions improving bioenergetic status may help prevent severe ROP. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03201588.

Humans↗
PubMed2006

Proceedings of the Third International Symposium on Retinopathy of Prematurity: an update on ROP from the lab to the nursery (November 2003, Anaheim, California).

The Third International Symposium on Retinopathy of Prematurity (ROP) was convened with the aim of cross fertilizing the horizons of basic and clinical scientists with an interest in the pathogenesis and management of infants with ROP. Ten speakers in the clinical sciences and ten speakers in the basic sciences were recruited on the basis of their research to provide state of the art talks. The meeting was held November 9, 2003 immediately prior to the American Academy of Ophthalmology meeting; scholarships were provided for outreach to developing countries and young investigators. This review contain the summaries of the 20 platform presentations prepared by the authors and the abstracts of presented posters. Each author was asked to encapsulate the current state of understanding, identify areas of controversy, and make recommendations for future research. The basic science presentations included insights into the development of the human retinal vasculature, animal models for ROP, growth factors that affect normal development and ROP, and promising new therapeutic approaches to treating ROP like VEGF targeting, inhibition of proteases, stem cells, ribozymes to silence genes, and gene therapy to deliver antiangiogenic agents. The clinical presentations included new insights into oxygen management, updates on the CRYO-ROP and ETROP studies, visual function in childhood following ROP, the neural retina in ROP, screening for ROP, management of stage 3 and 4 ROP, ROP in the third world, and the complications of ROP in adult life. The meeting resulted in a penetrating exchange between clinicians and basic scientists, which provided great insights for conference attendees. The effect of preterm delivery on the normal cross-talk of neuroretinal and retinal vascular development is a fertile ground for discovering new understanding of the processes involved both in normal development and in retinal neovascular disorders. The meeting also suggested promising potential therapeutic interventions on the horizon for ROP.

Humans↗
PubMed2006

Longitudinal postnatal weight and insulin-like growth factor I measurements in the prediction of retinopathy of prematurity.

OBJECTIVE: To investigate whether postnatal growth and development influence retinopathy of prematurity (ROP) and may be included in screening for ROP. DESIGN: We developed an algorithm to predict for individual infants the risk of later ROP development requiring treatment based on the postnatal longitudinal systemic factors of insulin-like growth factor I (IGF-I) level, IGF binding protein 3 level, and postnatal weight gain. We developed the algorithm based on 79 preterm infants considered at risk for ROP by standard criteria (gestational age, 23.6-31.7 weeks) in a longitudinal study measuring weight gain and serum IGF-I and IGF binding protein 3 levels weekly from birth until discharge from the hospital. We monitored deviations from reference models for weight and IGF-I level (preterm children who developed no or minimal ROP) to detect indications for treatable ROP by Early Treatment for Retinopathy of Prematurity study criteria. RESULTS: This monitoring method detected 6 (100%) of 6 infants in this cohort who required treatment for ROP with a warning signal at least 5 weeks before requiring treatment and at least 3 weeks before the onset of stage 3 ROP. The majority of infants (61/73 infants) requiring no treatment were also correctly identified. CONCLUSIONS: Monitoring the postnatal factors of weight, IGF-I level, and IGF binding protein 3 level substantially enhances the clinician's ability to identify patients who will require treatment for ROP.

Algorithms↗
PubMed2006

Postnatal head growth deficit among premature infants parallels retinopathy of prematurity and insulin-like growth factor-1 deficit.

BACKGROUND: We hypothesized that in premature infants, retinal vascular growth retardation between birth and postmenstrual age of approximately 30 to 32 weeks that initiates retinopathy of prematurity is paralleled by brain growth retardation. METHODS: In a prospective longitudinal study, we measured postnatal head growth, retinopathy of prematurity stage, protein and energy intake, severity of illness and serum insulin-like growth factor-1 levels in 58 preterm infants (mean gestational age at birth: 27.6 weeks) from birth until postmenstrual age of approximately 40 weeks. RESULTS: Premature infant head growth decelerates dramatically after birth until postmenstrual age of approximately 30 weeks. Head growth retardation coincides with retinal vascular growth suppression. Accelerated growth follows between post menstrual ages of approximately 30 to 32 weeks and approximately 40 weeks. The degree of head growth retardation up to postmenstrual age of 31 weeks corresponds to the degree of retinopathy of prematurity and to the degree of suppression of serum levels of insulin-like growth factor-1. At postmenstrual age of 31 weeks, if a child's head circumference SD is below -2.5, then the probability of also developing at least stage 3 retinopathy of prematurity increases fivefold compared with head circumference above -2.5 SD (32% vs 6%) suggesting parallel processes in brain and retina. Serum insulin-like growth factor-1 levels correlate positively with head circumference SD score and with the degree of retinopathy of prematurity. CONCLUSIONS: The correlation between head and retinal growth is consistent with insulin growth factor-1 being one of the postnatal growth factors involved in this multifactorial process and also suggests that factors that contribute to retinopathy of prematurity during this critical period may also affect neurological dysfunction. Additional studies are required to establish this connection.

Female↗
PubMed2005

Quantitative multi-gene transcriptional profiling using real-time PCR with a master template.

We previously reported a method for quantitative multi-gene transcriptional profiling with gene-specific standard curves using real-time PCR. Here, we report an approach that increases experimental throughput by using a master template to generate a single standard curve for the estimation of mRNA copy numbers from all genes. We prepared fifty-nine different templates and measured eNOS mRNA copy numbers in Matrigel VEGF-transfectant samples. The copy numbers obtained using each of the fifty-nine templates were within 50% of the copy number obtained using the previously reported method. Analysis of primer design parameters, and subsequent tests, showed that eliminating complementarities between the first nucleotides at the 5'-ends of the forward and reverse primers reduces the influence of saturation effects and produces copy numbers similar to those generated with gene-specific templates-generally, within 20%. Measurements on a panel consisting of eNOS, iNOS, and nNOS further validated the master-template approach. The master-template approach enables rapid quantification of mRNA abundances from panels of hundreds of genes, and will be a valuable tool for screening large numbers of genes as part of a search for biomarkers, the validation of DNA-microarray data, or research into the dynamics of the gene-protein network.

Cell Line, Tumor↗
PubMed2005

IGF-1 and retinopathy of prematurity in the preterm infant.

BACKGROUND: Retinopathy of prematurity (ROP) continues to be a major cause of blindness in children. Although ablation of the retina reduces the incidence of blindness by suppressing the neovascular phase of ROP, the visual outcomes after treatment are often poor. Preventive therapy is required and will likely come from a better understanding of the pathophysiology of the disease. OBJECTIVES: To study the role of insulin-like growth factor 1 (IGF-1) and vascular endothelial growth factor (VEGF) in both the proliferative phase of ROP (phase II) and in the early phase when blood vessels are lost. METHODS: Using both a mouse model of ROP and clinical studies the relationship between IGF-1, VEGF and both vessel loss and vessels proliferation in the retina was studied. RESULTS: IGF-1 is required for maximum VEGF activation of vascular endothelial cell proliferation and survival pathways. IGF-1 levels are deficient after premature birth, setting the stage for retinal vascular loss and ROP. CONCLUSIONS: Restoration of IGF-1 to levels found in utero may help prevent ROP.

Birth Weight↗
PubMed2005

Pigment epithelium-derived factor is a substrate for matrix metalloproteinase type 2 and type 9: implications for downregulation in hypoxia.

PURPOSE: Pigment epithelium-derived factor (PEDF), a protein secreted by the retinal pigment epithelium (RPE), acts on retinal survival and angiogenesis. Because hypoxia and VEGF regulate matrix metalloproteinases (MMPs), their effects on PEDF proteolysis were explored. METHODS: Mouse models for retinopathy of prematurity (ROP) were used. Cultured monkey RPE cells were exposed to low oxygen and chemical hypoxia mimetics. PEDF and VEGF mRNA levels in RPE were determined by RT-PCR. MMPs were assessed by zymography, DQ-gelatin degradation solution assays, and MMP immunostaining. PEDF proteolysis was assayed in solution and followed by SDS-PAGE and immunostaining. MMP induction by VEGF was performed in baby hamster kidney (BHK) cells. Retinal R28 cell survival, ex vivo chick embryonic aortic vessel sprouting, and directed in vivo angiogenesis assays were performed. RESULTS: Levels of PEDF in RPE/choroid significantly decreased in the ROP model. Hypoxia decreased PEDF levels in the media conditioned by RPE cells, with no significant change in PEDF mRNA. Conversely, PEDF proteolysis, gelatinolytic activities of approximately 57-kDa and approximately 86-kDa zymogens, and MMP-2 immunoreactivities increased with hypoxia. Addition of VEGF to BHK cells caused a time and dose-related upregulation of approximately 57-kDa zymogens and of DQ-gelatinolytic and PEDF-degrading activity. The PEDF-degrading activity and approximately 57-kDa zymogens in the BHK media shared MMP protease inhibition patterns and MMP-2 immunoreactivities with those in the vitreous. Limited proteolysis with MMP-2 and -9 degraded PEDF in a Ca(+2)-dependent fashion. MMP-mediated proteolysis of PEDF abolished the retinal survival and antiangiogenic activities of the PEDF protein. CONCLUSIONS: Hypoxia and VEGF can downregulate PEDF through proteolytic degradation. PEDF is a novel substrate for MMP-2 and -9. These results reveal a novel posttranslational mechanism for downregulating PEDF, and provide an explanation for hypoxia-provoked increases in VEGF/PEDF ratios, in angiogenesis and/or in neuronal death.

Animals↗
PubMed2004

Mechanical stretch is a highly selective regulator of gene expression in human bladder smooth muscle cells.

Application of mechanical stimuli has been shown to alter gene expression in bladder smooth muscle cells (SMC). To date, only a limited number of "stretch-responsive" genes in this cell type have been reported. We employed oligonucleotide arrays to identify stretch-sensitive genes in primary culture human bladder SMC subjected to repetitive mechanical stimulation for 4 h. Differential gene expression between stretched and nonstretched cells was assessed using Significance Analysis of Microarrays (SAM). Expression of 20 out of 11,731 expressed genes ( approximately 0.17%) was altered >2-fold following stretch, with 19 genes induced and one gene (FGF-9) repressed. Using real-time RT-PCR, we tested independently the responsiveness of 15 genes to stretch and to platelet-derived growth factor-BB (PDGF-BB), another hypertrophic stimulus for bladder SMC. In response to both stimuli, expression of 13 genes increased, 1 gene (FGF-9) decreased, and 1 gene was unchanged. Six transcripts (HB-EGF, BMP-2, COX-2, LIF, PAR-2, and FGF-9) were evaluated using an ex vivo rat model of bladder distension. HB-EGF, BMP-2, COX-2, LIF, and PAR-2 increased with bladder stretch ex vivo, whereas FGF-9 decreased, consistent with expression changes observed in vitro. In silico analysis of microarray data using the FIRED algorithm identified c-jun, AP-1, ATF-2, and neurofibromin-1 (NF-1) as potential transcriptional mediators of stretch signals. Furthermore, the promoters of 9 of 13 stretch-responsive genes contained AP-1 binding sites. These observations identify stretch as a highly selective regulator of gene expression in bladder SMC. Moreover, they suggest that mechanical and growth factor signals converge on common transcriptional regulators that include members of the AP-1 family.

Algorithms↗
PubMed2004

Pathogenesis of retinopathy of prematurity.

Retinopathy of prematurity (ROP) is a major cause of blindness in children in developed countries. ROP is a two-phase disease, beginning with delayed retinal vascular growth after premature birth (Phase I). Phase II follows when Phase I-induced hypoxia releases factors to stimulate new blood vessel growth. Both oxygen-regulated and non-oxygen-regulated factors contribute to normal vascular development and retinal neovascularization. Vascular endothelial growth factor (VEGF) is an important oxygen-regulated factor. A critical non-oxygen-regulated growth factor is insulin-like growth factor-I (IGF-I). In knockout mice, lack of IGF-I prevents normal retinal vascular growth, despite the presence of VEGF, important to vessel development. In vitro, low IGF-I levels prevent VEGF-induced activation of Akt, a kinase critical for vascular endothelial cell survival. We found that premature infants who develop ROP have low levels of serum IGF-I compared to age-matched infants without disease. IGF-I is critical to normal vascular development. Low IGF-I predicts ROP in premature infants, and restoration of IGF-I to normal levels might prevent ROP.

Animals↗
PubMed2004

Bone marrow-derived stem cells preserve cone vision in retinitis pigmentosa.

Retinitis pigmentosa is a heritable group of blinding diseases resulting from loss of photoreceptors, primarily rods and secondarily cones, that mediate central vision. Loss of retinal vasculature is a presumed metabolic consequence of photoreceptor degeneration. A new study shows that autologous bone marrow-derived lineage-negative hematopoietic stem cells, which incorporate into the degenerating blood vessels in two murine models of retinitis pigmentosa, rd1 and rd10, prevent cone loss. The use of autologous bone marrow might avoid problems with rejection while preserving central cone vision in a wide variety of genetically disparate retinal degenerative diseases.

Animals↗
PubMed2003

Transforming growth factor beta1 induction of vascular endothelial growth factor receptor 1: mechanism of pericyte-induced vascular survival in vivo.

Degeneration of vessels precedes and precipitates the devastating ischemia of many diseases, including retinopathy of prematurity and diabetic retinopathy. Ischemia then leads to proliferative retinopathy and blindness. Understanding the mechanisms of blood vessel degeneration is critical to prevention of these diseases. Vessel loss is associated with oxygen-induced suppression of vascular endothelial growth factor (VEGF) and with pericyte (vascular smooth muscle cell) dropout. The molecular mechanism of pericyte protection of the vasculature is unknown. We show that transforming growth factor beta1 (TGF-beta1)-expressing pericytes are specifically found on vessels resistant to oxygen-induced loss. TGF-beta1 potently induces VEGF receptor 1 (VEGFR-1) expression in endothelial cells and thereby prevents oxygen-induced vessel loss in vivo. Vessel survival is further stimulated with a VEGFR-1-specific ligand, placental growth factor 1. TGF-beta1 induction of VEGFR-1 in endothelial cells explains pericyte protection of vessels and the selective vulnerability of neonatal vessels to oxygen. These results implicate induction and activation of VEGFR-1 as critical targets to prevent vessel loss.

Animals↗
PubMed2003

Pathogenesis of retinopathy of prematurity.

Retinopathy of prematurity (ROP) is a major cause of blindness in children in developed countries. ROP, a two-phase disease, is initiated with delayed retinal vascular growth after premature birth (phase I). Insufficient vascularization of the developing retina creates hypoxia, which precipitates the release of factors stimulating new and abnormal blood vessel growth (phase II). ROP develops because of abnormalities in both oxygen-regulated and non-oxygen-regulated factors, which affect both phases of the disease. Vascular endothelial growth factor (VEGF) is an important oxygen-regulated factor that, if suppressed, inhibits normal vessel growth, but in excess, precipitates retinal neovascularization. A critical non-oxygen-regulated growth factor is insulin-like growth factor (IGF-1). Similar to VEGF, low levels of IGF-1 prevent normal vessel growth (phase I), and higher levels allow neovascularization (phase II). We found that premature infants who develop ROP have low levels of serum IGF-1 compared with age-matched infants without disease. IGF-1 is critical to normal vascular development. Low IGF-1 predicts ROP, and restoration of IGF-1 to normal levels might prevent ROP.

Child↗
PubMed2003

Selective stimulation of VEGFR-1 prevents oxygen-induced retinal vascular degeneration in retinopathy of prematurity.

Oxygen administration to immature neonates suppresses VEGF-A expression in the retina, resulting in the catastrophic vessel loss that initiates retinopathy of prematurity. To investigate the mechanisms responsible for survival of blood vessels in the developing retina, we characterized two VEGF-A receptors, VEGF receptor-1 (VEGFR-1, also known as Flt-1) and VEGF receptor-2 (VEGFR-2, also known as Flk-1). Surprisingly, these two VEGF-A receptors differed markedly during normal retinal development in mice. At 5 days postpartum (P5), VEGFR-1 protein was colocalized with retinal vessels, whereas VEGFR-2 was detected only in the neural retina. Real-time RT-PCR identified a 60-fold induction of VEGFR-1 mRNA in retina from P3 (early vascularization) to P26 (fully vascularized), and no significant change in VEGFR-2 mRNA expression. Placental growth factor-1 (PlGF-1), which exclusively binds VEGFR-1, decreased hyperoxia-induced retinal vaso-obliteration from 22.2% to 5.1%, whereas VEGF-E, which exclusively binds VEGFR-2, had no effect on blood vessel survival. Importantly, under the same conditions, PlGF-1 did not increase vasoproliferation during (a). normal vessel growth, (b). revascularization following hyperoxia-induced ischemia, or (c). the vasoproliferative phase, indicating a selective function supporting blood vessel survival. We conclude that VEGFR-1 is critical in maintaining the vasculature of the neonatal retina, and that activation of VEGFR-1 by PlGF-1 is a selective strategy for preventing oxygen-induced retinal ischemia without provoking retinal neovascularization.

Animals↗
PubMed2003

Postnatal serum insulin-like growth factor I deficiency is associated with retinopathy of prematurity and other complications of premature birth.

OBJECTIVE: Insulin-like growth factor I (IGF-I) is necessary for normal development of retinal blood vessels in mice and humans. Because retinopathy of prematurity (ROP) is initiated by abnormal postnatal retinal development, we hypothesized that prolonged low IGF-I in premature infants might be a risk factor for ROP. DESIGN: We conducted a prospective, longitudinal study measuring serum IGF-I concentrations weekly in 84 premature infants from birth (postmenstrual ages: 24-32 weeks) until discharge from the hospital. Infants were evaluated for ROP and other morbidity of prematurity: bronchopulmonary dysplasia (BPD), intraventricular hemorrhage (IVH), and necrotizing enterocolitis (NEC). RESULTS: Low serum IGF-I values correlated with later development of ROP. The mean IGF-I +/- SEM level during postmenstrual ages 30-33 weeks was lowest with severe ROP (25 +/- 2.41 micro g/L), 29 +/- 1.76 micro g/L with moderate ROP, and 33 +/- 1.72 micro g/L with no ROP. The duration of low IGF-I also correlated strongly with the severity of ROP. The interval from birth until serum IGF-I levels reached >33 micro g/L was 23 +/- 2.6 days for no ROP, 44 +/- 4.8 days for moderate ROP, and 52 +/- 7.5 days for severe ROP. Each adjusted stepwise increase of 5 micro g/L in mean IGF-I during postmenstrual ages 30 to 33 weeks decreased the risk of proliferative ROP by 45%. Other complications (NEC, BPD, IVH) were correlated with ROP and with low IGF-I levels. The relative risk for any morbidity (ROP, BPD, IVH, or NEC) was increased 2.2-fold (95% confidence interval: 1.41-3.43) if IGF-I was <or=33 micro g/L at 33 weeks' postmenstrual age. CONCLUSIONS: These results indicate that persistent low serum concentrations of IGF-I after premature birth are associated with later development of ROP and other complications of prematurity. IGF-I is at least as strong a determinant of risk for ROP as postmenstrual age at birth and birth weight.

Birth Weight↗
PubMed2002

Molecular profiling of angiogenesis markers.

The goal of this study was to develop a sensitive, simple, and widely applicable assay to measure copy numbers of specific mRNAs using real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), and identify a profile of gene expression closely associated with angiogenesis. We measured a panel of nine potential angiogenesis markers from a mouse transgenic model of prostate adenocarcinoma (TRAMP) and a mouse skin model of vascular endothelial growth factor (VEGF)-driven angiogenesis. In both models, expression of VEGF correlated with expression of mRNAs encoding other angiogenic cytokines (angiopoietin-1 and angiopoietin-2), endothelial cell receptor tyrosine kinases (Flt-1, KDR, Tie-1), and endothelial cell adhesion molecules (VE-cadherin, PECAM-1). Relative to control, in dermis highly stimulated by VEGF, the Ang-2 mRNA transcript numbers increased 35-fold, PECAM-1 and VE-cadherin increased 10-fold, Tie-1 increased 8-fold, KDR and Flt-1 each increased 4-fold, and Ang-1 increased 2-fold. All transcript numbers were correspondingly reduced in skin with less VEGF expression, indicating a relationship of each of these seven markers with VEGF. Thus, this study identifies a highly efficient method for precise quantification of a panel of seven specific mRNAs that correlate with VEGF expression and VEGF-induced neovascularization, and it provides evidence that real-time quantitative RT-PCR offers a highly sensitive strategy for monitoring angiogenesis.

Adenocarcinoma↗