Enhanced attention in rats following blast-induced traumatic brain injury

Purpose

To evaluate visuo-cognitive sequelae following blast-induced traumatic brain injury in a rat model.

Methods

Rats were randomly assigned to one of four groups depending on the intensity/quantity of a blast received in a blast chamber: sham (no blast), low intensity (22 psi), medium intensity (26 psi), or three medium intensity blasts (26 psi × 3). After recovery, all subjects were given visual discrimination tasks of increasing complexity, until mastery. After behavioral training, visual function was assessed via spectral-domain optical coherence tomography and pattern electroretinogram, and the extent of retinal damage was quantified via immunohistochemistry of retinal ganglion cells.

Results

None of the measures assessing visual function revealed significant differences as a function of blast intensity/quantity. Behavioral training did not disclose short-term effects of blast in general motivation or the development of anticipatory responding. No differences in general learning ability and the number of perseverative errors were observed. However, behavioral training found effects of blast in attentional function; relative to controls, subjects that received blasts were faster in learning to attend to informative (over non-informative) cues in the most difficult visual discrimination task.

Conclusion

Blast exposure in rats resulted in increased attention following blast, with no appreciable deficits in visual function. These results are contrary to what is often reported for human clinical populations; as such, more research bridging methodological differences is necessary.

Increasing the number and intensity of shock tube generated blast waves leads to earlier retinal ganglion cell dysfunction and regional cell death

The purpose of this study was to examine the effect of a blast exposure generated from a shock tube on retinal ganglion cell (RGC) function and structure. Mice were exposed to one of three blast conditions using a shock tube; a single blast wave of 20 PSI, a single blast wave of 30 PSI, or three blast waves of 30 PSI given on three consecutive days with a one-day inter-blast interval. The structure and function of the retina were analyzed using the pattern electroretinogram (PERG), the optomotor reflex (OMR), and optical coherence tomography (OCT). The in vivo parameters were examined at baseline, and then again 1-week, 4-weeks, and 16-weeks following blast exposure. The number of surviving RGCs was quantified at the end of the study. Analysis of mice receiving a 20 PSI injury showed decreased PERG and OMR responses 16-weeks post blast, without evidence of changed retinal thickness or RGC death. Mice subjected to a 30 PSI injury showed decreased PERG responses 4 weeks and 16 weeks after injury, without changes in the retinal thickness or RGC density. Mice subjected to 30 PSI X 3 blast exposures had PERG deficits 1-week and 4-weeks post exposure. There was also significant change in retinal thickness 1-week and 16-weeks post blast exposure. Mice receiving 30 PSI X 3 blast injuries had regional loss of RGCs in the central retina, but not in the mid-peripheral or peripheral retina. Overall, this study has shown that increasing the number of blast exposures and the intensity leads to earlier functional loss of RGCs. We have also shown regional RGC loss only when using the highest blast intensity and number of blast injuries.

Immune responses in mice after blast-mediated traumatic brain injury TBI autonomously contribute to retinal ganglion cell dysfunction and death

PURPOSE

The purpose of this study was to examine the role of the immune system and its influence on chronic retinal ganglion cell (RGC) dysfunction following blast-mediated traumatic brain injury (bTBI).

METHODS

C57BL/6J and B6.129S7-Rag1^tm1Mom/J (Rag^-/-) mice were exposed to one blast injury of 140 kPa. A separate cohort of C57BL/6J mice was exposed to sham-blast. Four weeks following bTBI mice were euthanized, and splenocytes were collected. Adoptive transfer (AT) of splenocytes into naïve C57BL/6J recipient mice was accomplished via tail vein injection. Three groups of mice were analyzed: those receiving AT of splenocytes from C57BL/6J mice exposed to blast (AT-TBI), those receiving AT of splenocytes from C57BL/6J mice exposed to sham (AT-Sham), and those receiving AT of splenocytes from Rag^-/- mice exposed to blast (AT-Rag^-/-). The visual function of recipient mice was analyzed with the pattern electroretinogram (PERG), and the optomotor response (OMR). The structure of the retina was evaluated using optical coherence tomography (OCT), and histologically using BRN3A-antibody staining.

RESULTS

Analysis of the PERG showed a decreased amplitude two months post-AT that persisted for the duration of the study in AT-TBI mice. We also observed a significant decrease in the retinal thickness of AT-TBI mice two months post-AT compared to sham, but not at four or six months post-AT. The OMR response was significantly decreased in AT-TBI mice 5- and 6-months post-AT. BRN3A staining showed a loss of RGCs in AT-TBI and AT-Rag^-/- mice.

CONCLUSION

These results suggest that the immune system contributes to chronic RGC dysfunction following bTBI.

Chronic effects of blast injury on the microvasculature in a transgenic mouse model of Alzheimer's disease related Aβ amyloidosis

BACKGROUND

Altered cerebrovascular function and accumulation of amyloid-β (Aβ) after traumatic brain injury (TBI) can contribute to chronic neuropathology and increase the risk for Alzheimer's disease (AD). TBI due to a blast-induced shock wave (bTBI) adversely affects the neurovascular unit (NVU) during the acute period after injury. However, the chronic effects of bTBI and Aβ on cellular components of the NVU and capillary network are not well understood.

METHODS

We exposed young adult (age range: 76-106 days) female transgenic (Tg) APP/PS1 mice, a model of AD-like Aβ amyloidosis, and wild type (Wt) mice to a single bTBI (~ 138 kPa or ~ 20 psi) or to a Sham procedure. At 3-months or 12-months survival after exposure, we quantified neocortical Aβ load in Tg mice, and percent contact area between aquaporin-4 (AQP4)-immunoreactive astrocytic end-feet and brain capillaries, numbers of PDGFRβ-immunoreactive pericytes, and capillary densities in both genotypes.

RESULTS

The astroglia AQP4-capillary contact area in the Tg-bTBI group was significantly lower than in the Tg-Sham group at 3-months survival. No significant changes in the AQP4-capillary contact area were observed in the Tg-bTBI group at 12-months survival or in the Wt groups. Capillary density in the Tg-bTBI group at 12-months survival was significantly higher compared to the Tg-Sham control and to the Tg-bTBI 3-months survival group. The Wt-bTBI group had significantly lower capillary density and pericyte numbers at 12-months survival compared to 3-months survival. When pericytes were quantified relative to capillary density, no significant differences were detected among the experimental groups, for both genotypes.

CONCLUSION

In conditions of high brain concentrations of human Aβ, bTBI exposure results in reduced AQP4 expression at the astroglia-microvascular interface, and in chronic capillary proliferation like what has been reported in AD. Long term microvascular changes after bTBI may contribute to the risk for developing chronic neurodegenerative disease later in life.

Decreased expression of glial-derived neurotrophic factor receptors in glaucomatous human retinas

PURPOSE

The purpose of this study was to examine the expression of glial derived neurotrophic factor (GDNF), the GDNF receptors GFRα1 and GFRα2, ciliary neurotrophic factor (CNTF), and the CNTF receptor CNTFRα in normal and glaucomatous human tissue.

METHODS

Human retinas were collected from 8 donors that had been clinically diagnosed and treated for glaucoma, and also from 9 healthy control donors. Immunohistochemical analysis for each trophic factor and receptor was performed. The percent of each retinal section labeled with each antibody was quantified for the total retinal thickness, and separately for the retinal ganglion cell (RGC) complex + retinal nerve fiber layer (RNFL). The expression of each protein was correlated with measures of the subject's ocular histories.

RESULTS

The percentage area immunopositive for GFRα2 was significantly decreased in the total retinal thickness containing all retinal layers and in the combined RGC complex + RNFL in glaucomatous eyes in both the peripapillary region and more peripheral retinal locations. We also observed a decrease in GFRα1 expression in the peripapillary RGC Complex + RNFL in glaucoma patients compared to healthy control patients. We also observed a relationship between GDNF and its receptors with several outcomes obtained from the medical record. No differences in CNTF or CNTFR labeling were observed.

CONCLUSION

Decreases in GDNF receptor expression in glaucomatous tissue may limit the potential for neuroprotective therapy by supplementation with GDNF.

The Retinal Ganglion Cell Response to Blast-Mediated Traumatic Brain Injury Is Genetic Background Dependent

Purpose

The purpose of this study was to examine the influence of genetic background on the retinal ganglion cell (RGC) response to blast-mediated traumatic brain injury (TBI) in Jackson Diversity Outbred (J:DO), C57BL/6J and BALB/cByJ mice.

Methods

Mice were subject to one blast injury of 137 kPa. RGC structure was analyzed by optical coherence tomography (OCT), function by the pattern electroretinogram (PERG), and histologically using BRN3A antibody staining.

Results

Comparison of the change in each group from baseline for OCT and PERG was performed. There was a significant difference in the J:DOΔOCT compared to C57BL/6J mice (P = 0.004), but not compared to BALB/cByJ (P = 0.21). There was a significant difference in the variance of the ΔOCT in J:DO compared to both C57BL/6J and BALB/cByJ mice. The baseline PERG amplitude was 20.33 ± 9.32 µV, which decreased an average of −4.14 ± 12.46 µV following TBI. Baseline RGC complex + RNFL thickness was 70.92 ± 4.52 µm, which decreased an average of −1.43 ± 2.88 µm following blast exposure. There was not a significant difference in the ΔPERG between J:DO and C57BL/6J (P = 0.13), although the variances of the groups were significantly different. Blast exposure in J:DO mice results in a density change of 558.6 ± 440.5 BRN3A-positive RGCs/mm² (mean ± SD).

Conclusions

The changes in retinal outcomes had greater variance in outbred mice than what has been reported, and largely replicated herein, for inbred mice. These results demonstrate that the RGC response to blast injury is highly dependent upon genetic background.

Sex Does Not Influence Visual Outcomes After Blast-Mediated Traumatic Brain Injury but IL-1 Pathway Mutations Confer Partial Rescue

Purpose

In a mouse model of blast-mediated traumatic brain injury (bTBI), interleukin-1 (IL-1)-pathway components were tested as potential therapeutic targets for bTBI-mediated retinal ganglion cell (RGC) dysfunction. Sex was also evaluated as a variable for RGC outcomes post-bTBI.

Methods

Male and female mice with null mutations in genes encoding IL-1α, IL-1β, or IL-1RI were compared to C57BL/6J wild-type (WT) mice after exposure to three 20-psi blast waves given at an interblast interval of 1 hour or to mice receiving sham injury. To determine if genetic blockade of IL-1α, IL-1β, or IL-1RI could prevent damage to RGCs, the function and structure of these cells were evaluated by pattern electroretinogram and optical coherence tomography, respectively, 5 weeks following blast or sham exposure. RGC survival was also quantitatively assessed via immunohistochemical staining of BRN3A at the completion of the study.

Results

Our results showed that male and female WT mice had a similar response to blast-induced retinal injury. Generally, constitutive deletion of IL-1α, IL-1β, or IL-1RI did not provide full protection from the effects of bTBI on visual outcomes; however, injured WT mice had significantly worse visual outcomes compared to the injured genetic knockout mice.

Conclusions

Sex does not affect RGC outcomes after bTBI. The genetic studies suggest that deletion of these IL-1 pathway components confers some protection, but global deletion from birth did not result in a complete rescue.

Characterization of the Jet-Flow Overpressure Model of Traumatic Brain Injury in Mice

The jet-flow overpressure chamber (OPC) has been previously reported as a model of blast-mediated traumatic brain injury (bTBI). However, rigorous characterization of the features of this injury apparatus shows that it fails to recapitulate exposure to an isolated blast wave. Through combined experimental and computational modeling analysis of gas-dynamic flow conditions, we show here that the jet-flow OPC produces a collimated high-speed jet flow with extreme dynamic pressure that delivers a severe compressive impulse. Variable rupture dynamics of the diaphragm through which the jet flow originates also generate a weak and infrequent shock front. In addition, there is a component of acceleration-deceleration injury to the head as it is agitated in the headrest. Although not a faithful model of free-field blast exposure, the jet-flow OPC produces a complex multi-modal model of TBI that can be useful in laboratory investigation of putative TBI therapies and fundamental neurophysiological processes after brain injury.

High Correlation between Glaucoma Treatment with Topical Prostaglandin Analogs and BDNF Immunoreactivity in Human Retina

PURPOSE

To examine the expression of brain-derived neurotrophic factor (BDNF) and its high-affinity receptor, tropomyosin-related kinase receptor-B (TrkB), in normal and glaucomatous human retinas.

METHODS

Human retinas were collected from 8 donors who had been clinically diagnosed and treated for glaucoma, and from 9 control donors. Immunohistochemical analysis for BDNF and TrkB was performed. The percent of each retina expressing BDNF and TrkB was quantified for the total retinal thickness, and separately for the retinal ganglion cell (RGC) complex + retinal nerve fiber layer (RNFL). The expression of each protein was correlated with clinical outcomes obtained from the subject's ocular histories.

RESULTS

There was no significant difference in BDNF or TrkB expression when comparing glaucomatous and control retinas. Correlation analysis revealed a significant relationship between BDNF expression and the use of prostaglandin analogs. TrkB expression was highly correlated with the last-measured intraocular pressure (IOP), the use of carbonic anhydrase inhibitors, the use of beta blockers, and the total number of drugs used for the treatment of glaucoma.

CONCLUSION

Topical drugs used to treat glaucoma were associated with an increase in retinal BDNF and TrkB expression in human retina, independent of IOP, which may represent molecular evidence of neuroprotective pathway activation.

Modulation of Post-Traumatic Immune Response Using the IL-1 Receptor Antagonist Anakinra for Improved Visual Outcomes

The purpose of this study was to characterize acute changes in inflammatory pathways in the mouse eye after blast-mediated traumatic brain injury (bTBI) and to determine whether modulation of these pathways could protect the structure and function of retinal ganglion cells (RGC). The bTBI was induced in C57BL/6J male mice by exposure to three 20 psi blast waves directed toward the head with the body shielded, with an inter-blast interval of one hour. Acute cytokine expression in retinal tissue was measured through reverse transcription-quantitative polymerase chain reaction (RT-qPCR) four hours post-blast. Increased retinal expression of interleukin (lL)-1β, IL-1α, IL-6, and tumor necrosis factor (TNF)α was observed in bTBI mice exposed to blast when compared with shams, which was associated with activation of microglia and macroglia reactivity, assessed via immunohistochemistry with ionized calcium binding adaptor molecule 1 and glial fibrillary acidic protein, respectively, one week post-blast. Blockade of the IL-1 pathway was accomplished using anakinra, an IL-1RI antagonist, administered intra-peritoneally for one week before injury and continuing for three weeks post-injury. Retinal function and RGC layer thickness were evaluated four weeks post-injury using pattern electroretinogram (PERG) and optical coherence tomography (OCT), respectively. After bTBI, anakinra treatment resulted in a preservation of RGC function and RGC structure when compared with saline treated bTBI mice. Optic nerve integrity analysis demonstrated a trend of decreased damage suggesting that IL-1 blockade also prevents axonal damage after blast. Blast exposure results in increased retinal inflammation including upregulation of pro-inflammatory cytokines and activation of resident microglia and macroglia. This may explain partially the RGC loss we observed in this model, as blockade of the acute inflammatory response after injury with the IL-1R1 antagonist anakinra resulted in preservation of RGC function and RGC layer thickness.

Identification of chronic brain protein changes and protein targets of serum auto-antibodies after blast-mediated traumatic brain injury

In addition to needing acute emergency management, blast-mediated traumatic brain injury (TBI) is also a chronic disorder with delayed-onset symptoms that manifest and progress over time. While the immediate consequences of acute blast injuries are readily apparent, chronic sequelae are harder to recognize. Indeed, the identification of individuals with mild-TBI or TBI-induced symptoms is greatly impaired in large part due to the lack of objective and robust biomarkers. The purpose of this study was to address these need by identifying candidates for serum-based biomarkers of blast TBI, and also to identify unique or differentially regulated protein expression in the thalamus in C57BL/6J mice exposed to blast using high throughput qualitative screens of protein expression. To identify thalamic proteins differentially or uniquely associated with blast exposure, we utilized an antibody-based affinity-capture strategy (referred to as "proteomics-based analysis of depletomes"; PAD) to deplete thalamic lysates from blast-treated mice of endogenous thalamic proteins also found in control mice. Analysis of this "depletome" detected 75 unique proteins, many with associations to the myelin sheath. To identify blast-associated proteins eliciting production of circulating autoantibodies, serum antibodies of blast-treated mice were immobilized, and their immunogens subsequently identified by proteomic analysis of proteins specifically captured following incubation with thalamic lysates (a variant of a strategy referred to as "proteomics-based expression library screening"; PELS). This analysis identified 46 blast-associated immunogenic proteins, including 6 shared in common with the PAD analysis (ALDOA, PHKB, HBA-A1, DPYSL2, SYN1, and CKB). These proteins and their autoantibodies are appropriate for further consideration as biomarkers of blast-mediated TBI.

Blast-Mediated Traumatic Brain Injury Exacerbates Retinal Damage and Amyloidosis in the APPswePSENd19e Mouse Model of Alzheimer's Disease

Purpose

Traumatic brain injury (TBI) is a risk factor for developing chronic neurodegenerative conditions including Alzheimer's disease (AD). The purpose of this study was to examine chronic effects of blast TBI on retinal ganglion cells (RGC), optic nerve, and brain amyloid load in a mouse model of AD amyloidosis.

Methods

Transgenic (TG) double-mutant APPswePSENd19e (APP/PS1) mice and nontransgenic (Non-TG) littermates were exposed to a single blast TBI (20 psi) at age 2 to 3 months. RGC cell structure and function was evaluated 2 months later (average age at endpoint = 4.5 months) using pattern electroretinogram (PERG), optical coherence tomography (OCT), and the chromatic pupil light reflex (cPLR), followed by histologic analysis of retina, optic nerve, and brain amyloid pathology.

Results

APP/PS1 mice exposed to blast TBI (TG-Blast) had significantly lower PERG and cPLR responses 2 months after injury compared to preblast values and compared to sham groups of APP/PS1 (TG-Sham) and nontransgenic (Non-TG-Sham) mice as well as nontransgenic blast-exposed mice (Non-TG-Blast). The TG-Blast group also had significantly thinner RGC complex and more optic nerve damage compared to all groups. No amyloid-β (Aβ) deposits were detected in retinas of APP/PS1 mice; however, increased amyloid precursor protein (APP)/Aβ-immunoreactivity was seen in TG-Blast compared to TG-Sham mice, particularly near blood vessels. TG-Blast and TG-Sham groups exhibited high variability in pathology severity, with a strong, but not statistically significant, trend for greater cerebral cortical Aβ plaque load in the TG-Blast compared to TG-Sham group.

Conclusions

When combined with a genetic susceptibility for developing amyloidosis of AD, blast TBI exposure leads to earlier RGC and optic nerve damage associated with modest but detectable increase in cerebral cortical Aβ pathology. These findings suggest that genetic risk factors for AD may increase the sensitivity of the retina to blast-mediated damage.

Blast Preconditioning Protects Retinal Ganglion Cells and Reveals Targets for Prevention of Neurodegeneration Following Blast-Mediated Traumatic Brian Injury

Purpose

The purpose of this study was to examine the effect of multiple blast exposures and blast preconditioning on the structure and function of retinal ganglion cells (RGCs), to identify molecular pathways that contribute to RGC loss, and to evaluate the role of kynurenine-3-monooxygenase (KMO) inhibition on RGC structure and function.

Methods

Mice were subjected to sham blast injury, one single blast injury, or three blast injuries separated by either 1 hour or 1 week, using a blast intensity of 20 PSI. To examine the effect of blast preconditioning, mice were subjected to sham blast injury, one single 20-PSI injury, or three blast injuries separated by 1 week (5 PSI, 5 PSI, 20 PSI and 5 PSI, 5 PSI, 5 PSI). RGC structure was analyzed by optical coherence tomography (OCT) and function was analyzed by the pattern electroretinogram (PERG). BRN3A-positive cells were quantified to determine RGC density. RNA-seq analysis was used to identify transcriptional changes between groups.

Results

Analysis of mice with multiple blast exposures of 20 PSI revealed no significant differences compared to one 20-pounds per square inch (PSI) exposure using OCT, PERG, or BRN3A cell counts. Analysis of mice exposed to two preconditioning 5-PSI blasts prior to one 20-PSI blast showed preservation of RGC structure and function. RNA-seq analysis of the retina identified multiple transcriptomic changes between conditions. Pharmacologic inhibition of KMO preserved RGC responses compared to vehicle-treated mice.

Conclusions

Preconditioning protects RGC from blast injury. Protective effects appear to involve changes in KMO activity, whose inhibition is also protective.

Neprilysin inhibition promotes corneal wound healing

Neprilysin (NEP), an ectoenzyme that modulates inflammation by degrading neuropeptides, was recently identified in the human corneal epithelium. The cornea expresses many NEP substrates, but the function of NEP in homeostatic maintenance and wound healing of the cornea is unknown. We therefore investigated the role of this enzyme under naive and injured conditions using NEP-deficient (NEP-/-) and wild type (WT) control mice. In vivo ocular surface imaging and histological analysis of corneal tissue showed no differences in limbal vasculature or corneal anatomy between naive NEP-/- and WT mice. Histological examination revealed increased corneal innervation in NEP-/- mice. In an alkali burn model of corneal injury, corneal wound healing was significantly accelerated in NEP-/- mice compared to WT controls 3 days after injury. Daily intraperitoneal administration of the NEP inhibitor thiorphan also accelerated corneal wound healing after alkali injury in WT mice. Collectively, our data identify a previously unknown role of NEP in the cornea, in which pharmacologic inhibition of its activity may provide a novel therapeutic option for patients with corneal injury.

Extracellular superoxide dismutase (SOD3) regulates oxidative stress at the vitreoretinal interface

Oxidative stress is a pathogenic feature in vitreoretinal disease. However, the ability of the inner retina to manage metabolic waste and oxidative stress is unknown. Proteomic analysis of antioxidants in the human vitreous, the extracellular matrix opposing the inner retina, identified superoxide dismutase-3 (SOD3) that localized to a unique matrix structure in the vitreous base and cortex. To determine the role of SOD3, Sod3^-/- mice underwent histological and clinical phenotyping. Although the eyes were structurally normal, at the vitreoretinal interface Sod3^-/- mice demonstrated higher levels of 3-nitrotyrosine, a key marker of oxidative stress. Pattern electroretinography also showed physiological signaling abnormalities within the inner retina. Vitreous biopsies and epiretinal membranes collected from patients with diabetic vitreoretinopathy (DVR) and a mouse model of DVR showed significantly higher levels of nitrates and/or 3-nitrotyrosine oxidative stress biomarkers suggestive of SOD3 dysfunction. This study analyzes the molecular pathways that regulate oxidative stress in human vitreous substructures. The absence or dysregulation of the SOD3 antioxidant at the vitreous base and cortex results in increased oxidative stress and tissue damage to the inner retina, which may underlie DVR pathogenesis and other vitreoretinal diseases.

Randomized Trial of Motivational Interviewing to Prevent Early Childhood Caries in American Indian Children

Introduction

In a randomized controlled trial, the effectiveness of motivational interviewing (MI) combined with enhanced community services (MI + ECS) was compared with ECS alone for reducing dental caries in American Indian children on the Pine Ridge Reservation. The intervention was developed and delivered with extensive tribal collaboration.

Methods

A total 579 mother-newborn dyads were enrolled and randomized to the MI + ECS and ECS groups. They were followed for 36 mo. Four MI sessions were provided, the first shortly after childbirth and then 6, 12, and 18 mo later. Both groups were exposed to ECS, which included public service announcements through billboards and tribal radio, as well as broad distribution of brochures on behavioral risk factors for early childhood caries (ECC), toothbrushes, and toothpaste. MI impact was measured as decayed, missing, and filled tooth surfaces (dmfs). Secondary outcomes included decayed surfaces, caries prevalence, and maternal oral health knowledge and behaviors. Modified intention-to-treat analyses were conducted. Eighty-eight percent of mothers completed at least 3 of 4 MI sessions offered.

Results

After 3 y, dmfs was not significantly different for the 2 groups (MI + ECS = 10, ECS = 10.38, P = 0.68). In both groups, prevalence of caries experience was 7% to 9% after 1 y, 35% to 36% at 2 y, and 55% to 56% at 3 y. Mean knowledge scores increased by 5.0, 5.3, and 5.9 percentage points at years 1, 2, and 3 in the MI + ECS group and by 1.9, 3.3, and 5.0 percentage points in the ECS group (P = 0.03), respectively. Mean maternal oral health behavior scores were not statistically significantly different between the treatment arms.

Conclusion

In summary, the MI intervention appeared to improve maternal knowledge but had no effect on oral health behaviors or on the progression of ECC (ClinicalTrials.gov NCT01116726).

Knowledge Transfer Statement

The findings of this study suggest that motivational interviewing focusing on parental behaviors may not be as effective as previously hoped for slowing the development of childhood caries in some high-risk groups. Furthermore, social factors may be even more salient determinants of oral health than what we previously supposed, perhaps interfering with the capacity to benefit from behavioral strategies that have been useful elsewhere. The improvement of children's oral health in high-risk populations characterized by poverty and multiple related life stresses may require more holistic approaches that address these formidable barriers.

Effect of diet-induced obesity or type 1 or type 2 diabetes on corneal nerves and peripheral neuropathy in C57Bl/6J mice

We determined the impact diet-induced obesity (DIO) and types 1 and 2 diabetes have on peripheral neuropathy with emphasis on corneal nerve structural changes in C57Bl/6J mice. Endpoints examined included nerve conduction velocity, response to thermal and mechanical stimuli and innervation of the skin and cornea. DIO mice and to a greater extent type 2 diabetic mice were insulin resistant. DIO and both types 1 and 2 diabetic mice developed motor and sensory nerve conduction deficits. In the cornea of DIO and type 2 diabetic mice there was a decrease in sub-epithelial corneal nerves, innervation of the corneal epithelium, and corneal sensitivity. Type 1 diabetic mice did not present with any significant changes in corneal nerve structure until after 20 weeks of hyperglycemia. DIO and type 2 diabetic mice developed corneal structural damage more rapidly than type 1 diabetic mice although hemoglobin A1 C values were significantly higher in type 1 diabetic mice. This suggests that DIO with or without hyperglycemia contributes to development and progression of peripheral neuropathy and nerve structural damage in the cornea.

Effect of glycemic control on corneal nerves and peripheral neuropathy in streptozotocin-induced diabetic C57Bl/6J mice

We sought to determine the impact that duration of hyperglycemia and control has on corneal nerve fiber density in relation to standard diabetic neuropathy endpoints. Control and streptozotocin-diabetic C57Bl/6J mice were analyzed after 4, 8, 12, and 20 weeks. For the 20-week time point, five groups of mice were compared: control, untreated diabetic, and diabetic treated with insulin designated as having either poor glycemic control, good glycemic control, or poor glycemic control switched to good glycemic control. Hyperglycemia was regulated by use of insulin-releasing pellets. Loss of corneal nerves in the sub-epithelial nerve plexus or corneal epithelium progressed slowly in diabetic mice requiring 20 weeks to reach statistical significance. In comparison, slowing of motor and sensory nerve conduction velocity developed rapidly with significant difference compared with control mice observed after 4 and 8 weeks of hyperglycemia, respectively. In diabetic mice with good glycemic control, average blood glucose levels over the 20-week experimental period were lowered from 589 ± 2 to 251 ± 9 mg/dl. All diabetic neuropathy endpoints examined were improved in diabetic mice with good glycemic control compared with untreated diabetic mice. However, good control of blood glucose was not totally sufficient in preventing diabetic neuropathy.

RetFM-J, an ImageJ-based module for automated counting and quantifying features of nuclei in retinal whole-mounts

The present article introduces RetFM-J, a semi-automated ImageJ-based module that detects, counts, and collects quantitative data on nuclei of the inner retina from H&E-stained whole-mounted retinas. To illustrate performance, computer-derived outputs were analyzed in inbred C57BL/6J mice. Automated characterization yielded computer-derived outputs that closely matched manual counts. As a method using open-source software that is freely available, inexpensive staining reagents that are robust, and imaging equipment that is routine to most laboratories, RetFM-J could be utilized in a wide variety of experiments benefiting from high-throughput, quantitative, uniform analyses of total cellularity in the inner retina.

Effect of enriching the diet with menhaden oil or daily treatment with resolvin D1 on neuropathy in a mouse model of type 2 diabetes

The purpose of this study was to determine the effect of supplementing the diet of a mouse model of type 2 diabetes with menhaden (fish) oil or daily treatment with resolvin D1 on diabetic neuropathy. The end points evaluated included motor and sensory nerve conduction velocity, thermal sensitivity, innervation of sensory nerves in the cornea and skin, and the retinal ganglion cell complex thickness. Menhaden oil is a natural source for n-3 polyunsaturated fatty acids, which have been shown to have beneficial effects in other diseases. Resolvin D1 is a metabolite of docosahexaenoic acid and is known to have anti-inflammatory and neuroprotective properties. To model type 2 diabetes, mice were fed a high-fat diet for 8 wk followed by a low dosage of streptozotocin. After 8 wk of hyperglycemia, mice in experimental groups were treated for 6 wk with menhaden oil in the diet or daily injections of 1 ng/g body wt resolvin D1. Our findings show that menhaden oil or resolvin D1 did not improve elevated blood glucose, HbA1C, or glucose utilization. Untreated diabetic mice were thermal hypoalgesic, had reduced motor and sensory nerve conduction velocities, had decreased innervation of the cornea and skin, and had thinner retinal ganglion cell complex. These end points were significantly improved with menhaden oil or resolvin D1 treatment. Exogenously, resolvin D1 stimulated neurite outgrowth from primary cultures of dorsal root ganglion neurons from normal mice. These studies suggest that n-3 polyunsaturated fatty acids derived from fish oil could be an effective treatment for diabetic neuropathy.

Early detection of subclinical visual damage after blast-mediated TBI enables prevention of chronic visual deficit by treatment with P7C3-S243

PURPOSE

Traumatic brain injury (TBI) frequently leads to chronic visual dysfunction. The purpose of this study was to investigate the effect of TBI on retinal ganglion cells (RGCs), and to test whether treatment with the novel neuroprotective compound P7C3-S243 could prevent in vivo functional deficits in the visual system.

METHODS

Blast-mediated TBI was modeled using an enclosed over-pressure blast chamber. The RGC physiology was evaluated using a multielectrode array and pattern electroretinogram (PERG). Histological analysis of RGC dendritic field and cell number were evaluated at the end of the study. Visual outcome measures also were evaluated based on treatment of mice with P7C3-S243 or vehicle control.

RESULTS

We show that deficits in neutral position PERG after blast-mediated TBI occur in a temporally bimodal fashion, with temporary recovery 4 weeks after injury followed by chronically persistent dysfunction 12 weeks later. This later time point is associated with development of dendritic abnormalities and irreversible death of RGCs. We also demonstrate that ongoing pathologic processes during the temporary recovery latent period (including abnormalities of RGC physiology) lead to future dysfunction of the visual system. We report that modification of PERG to provocative postural tilt testing elicits changes in PERG measurements that correlate with a key in vitro measures of damage: the spontaneous and light-evoked activity of RGCs. Treatment with P7C3-S243 immediately after injury and throughout the temporary recovery latent period protects mice from developing chronic visual system dysfunction.

CONCLUSIONS

Provocative PERG testing serves as a noninvasive test in the living organism to identify early damage to the visual system, which may reflect corresponding damage in the brain that is not otherwise detectable by noninvasive means. This provides the basis for developing an earlier diagnostic test to identify patients at risk for developing chronic CNS and visual system damage after TBI at an earlier stage when treatments may be more effective in preventing these sequelae. In addition, treatment with the neuroprotective agent P7C3-S243 after TBI protects from visual system dysfunction after TBI.

P7C3 neuroprotective chemicals block axonal degeneration and preserve function after traumatic brain injury

The P7C3 class of neuroprotective aminopropyl carbazoles has been shown to block neuronal cell death in models of neurodegeneration. We now show that P7C3 molecules additionally preserve axonal integrity after injury, before neuronal cell death occurs, in a rodent model of blast-mediated traumatic brain injury (TBI). This protective quality may be linked to the ability of P7C3 molecules to activate nicotinamide phosphoribosyltransferase, the rate-limiting enzyme in nicotinamide adenine dinucleotide salvage. Initiation of daily treatment with our recently reported lead agent, P7C3-S243, 1 day after blast-mediated TBI blocks axonal degeneration and preserves normal synaptic activity, learning and memory, and motor coordination in mice. We additionally report persistent neurologic deficits and acquisition of an anxiety-like phenotype in untreated animals 8 months after blast exposure. Optimized variants of P7C3 thus offer hope for identifying neuroprotective agents for conditions involving axonal damage, neuronal cell death, or both, such as occurs in TBI.

Detection and characterization of glaucoma-like canine retinal tissues using Raman spectroscopy

Early detection of pathological changes and progression in glaucoma and other neuroretinal diseases remains a great challenge and is critical to reduce permanent structural and functional retina and optic nerve damage. Raman spectroscopy is a sensitive technique that provides rapid biochemical characterization of tissues in a nondestructive and noninvasive fashion. In this study, spectroscopic analysis was conducted on the retinal tissues of seven beagles with acute elevation of intraocular pressure (AEIOP), six beagles with compressive optic neuropathy (CON), and five healthy beagles. Spectroscopic markers were identified associated with the different neuropathic conditions. Furthermore, the Raman spectra were subjected to multivariate discriminate analysis to classify independent tissue samples into diseased/healthy categories. The multivariate discriminant model yielded an average optimal classification accuracy of 72.6% for AEIOP and 63.4% for CON with 20 principal components being used that accounted for 87% of the total variance in the data set. A strong correlation (R2>0.92) was observed between pattern electroretinography characteristics of AEIOP dogs and Raman separation distance that measures the separation of spectra of diseased tissues from normal tissues; however, the underlining mechanism of this correlation remains to be understood. Since AEIOP mimics the pathological symptoms of acute/early-stage glaucoma, it was demonstrated that Raman spectroscopic screening has the potential to become a powerful tool for the detection and characterization of early-stage disease.

Retinal ganglion cell damage in an experimental rodent model of blast-mediated traumatic brain injury

PURPOSE

To evaluate retina and optic nerve damage following experimental blast injury.

METHODS

Healthy adult mice were exposed to an overpressure blast wave using a custom-built blast chamber. The effects of blast exposure on retina and optic nerve function and structure were evaluated using the pattern electroretinogram (pERG), spectral domain optical coherence tomography (OCT), and the chromatic pupil light reflex.

RESULTS

Assessment of the pupil response to light demonstrated decreased maximum pupil constriction diameter in blast-injured mice using red light or blue light stimuli 24 hours after injury compared with baseline in the eye exposed to direct blast injury. A decrease in the pupil light reflex was not observed chronically following blast exposure. We observed a biphasic pERG decrease with the acute injury recovering by 24 hours postblast and the chronic injury appearing at 4 months postblast injury. Furthermore, at 3 months following injury, a significant decrease in the retinal nerve fiber layer was observed using OCT compared with controls. Histologic analysis of the retina and optic nerve revealed punctate regions of reduced cellularity in the ganglion cell layer and damage to optic nerves. Additionally, a significant upregulation of proteins associated with oxidative stress was observed acutely following blast exposure compared with control mice.

CONCLUSIONS

Our study demonstrates that decrements in retinal ganglion cell responses can be detected after blast injury using noninvasive functional and structural tests. These objective responses may serve as surrogate tests for higher CNS functions following traumatic brain injury that are difficult to quantify.

A combined machine-learning and graph-based framework for the segmentation of retinal surfaces in SD-OCT volumes

Optical coherence tomography is routinely used clinically for the detection and management of ocular diseases as well as in research where the studies may involve animals. This routine use requires that the developed automated segmentation methods not only be accurate and reliable, but also be adaptable to meet new requirements. We have previously proposed the use of a graph-theoretic approach for the automated 3-D segmentation of multiple retinal surfaces in volumetric human SD-OCT scans. The method ensures the global optimality of the set of surfaces with respect to a cost function. Cost functions have thus far been typically designed by hand by domain experts. This difficult and time-consuming task significantly impacts the adaptability of these methods to new models. Here, we describe a framework for the automated machine-learning based design of the cost function utilized by this graph-theoretic method. The impact of the learned components on the final segmentation accuracy are statistically assessed in order to tailor the method to specific applications. This adaptability is demonstrated by utilizing the method to segment seven, ten and five retinal surfaces from SD-OCT scans obtained from humans, mice and canines, respectively. The overall unsigned border position errors observed when using the recommended configuration of the graph-theoretic method was 6.45 ± 1.87 μm, 3.35 ± 0.62 μm and 9.75 ± 3.18 μm for the human, mouse and canine set of images, respectively.

Characterization of structure and function of the mouse retina using pattern electroretinography, pupil light reflex, and optical coherence tomography

OBJECTIVE

To perform in vivo analysis of retinal functional and structural parameters in healthy mouse eyes.

ANIMAL STUDIED

Adult C57BL/6 male mice (n = 37).

PROCEDURES

Retinal function was evaluated using pattern electroretinography (pERG) and the chromatic pupil light reflex (cPLR). Structural properties of the retina and nerve fiber layer (NFL) were evaluated using spectral-domain optical coherence tomography (SD-OCT).

RESULTS

The average pERG amplitudes were found to be 11.2 ± 0.7 μV (P50-N95, mean ± SEM), with an implicit time for P50-N95 interval of 90.4 ± 5.4 ms. Total retinal thickness was 229.5 ± 1.7 μm (mean ± SEM) in the area centralis region. The thickness of the retinal nerve fiber layer (mean ± SEM) using a circular peripapillary retinal scan centered on the optic nerve was 46.7 ± 0.9 μm (temporal), 46.1 ± 0.9 μm (superior), 45.8 ± 0.9 μm (nasal), and 48.4 ± 1 μm (inferior). The baseline pupil diameter was 2.1 ± 0.05 mm in darkness, and 1.1 ± 0.05 and 0.56 ± 0.03 mm after stimulation with red (630 nm, luminance 200 kcd/m(2)) or blue (480 nm, luminance 200 kcd/m(2)) light illumination, respectively.

CONCLUSIONS

Pattern electroretinography, cPLR and SD-OCT analysis are reproducible techniques, which can provide important information about retinal and optic nerve function and structure in mice.

Exploring Raman spectroscopy for the evaluation of glaucomatous retinal changes

Glaucoma is a chronic neurodegenerative disease characterized by apoptosis of retinal ganglion cells and subsequent loss of visual function. Early detection of glaucoma is critical for the prevention of permanent structural damage and irreversible vision loss. Raman spectroscopy is a technique that provides rapid biochemical characterization of tissues in a nondestructive and noninvasive fashion. In this study, we explored the potential of using Raman spectroscopy for detection of glaucomatous changes in vitro. Raman spectroscopic imaging was conducted on retinal tissues of dogs with hereditary glaucoma and healthy control dogs. The Raman spectra were subjected to multivariate discriminant analysis with a support vector machine algorithm, and a classification model was developed to differentiate disease tissues versus healthy tissues. Spectroscopic analysis of 105 retinal ganglion cells (RGCs) from glaucomatous dogs and 267 RGCs from healthy dogs revealed spectroscopic markers that differentiated glaucomatous specimens from healthy controls. Furthermore, the multivariate discriminant model differentiated healthy samples and glaucomatous samples with good accuracy [healthy 89.5% and glaucomatous 97.6% for the same breed (Basset Hounds); and healthy 85.0% and glaucomatous 85.5% for different breeds (Beagles versus Basset Hounds)]. Raman spectroscopic screening can be used for in vitro detection of glaucomatous changes in retinal tissue with a high specificity.

Transplantation of BDNF-secreting mesenchymal stem cells provides neuroprotection in chronically hypertensive rat eyes

PURPOSE

To evaluate the ability of mesenchymal stem cells (MSCs) engineered to produce and secrete brain-derived neurotrophic factor (BDNF) to protect retinal function and structure after intravitreal transplantation in a rat model of chronic ocular hypertension (COH).

METHODS

COH was induced by laser cauterization of trabecular meshwork and episcleral veins in rat eyes. COH eyes received an intravitreal transplant of MSCs engineered to express BDNF and green fluorescent protein (BDNF-MSCs) or just GFP (GFP-MSCs). Computerized pupillometry and electroretinography (ERG) were performed to assess optic nerve and retinal function. Quantification of optic nerve damage was performed by counting retinal ganglion cells (RGCs) and evaluating optic nerve cross-sections.

RESULTS

After transplantation into COH eyes, BDNF-MSCs preserved significantly more retina and optic nerve function than GFP-MSC-treated eyes when pupil light reflex (PLR) and ERG function were evaluated. PLR analysis showed significantly better function (P = 0.03) in BDNF-MSC-treated eyes (operated/control ratio = 63.00% ± 11.39%) than GFP-MSC-treated eyes (operated/control ratio = 31.81% ± 9.63%) at 42 days after surgery. The BDNF-MSC-transplanted eyes also displayed a greater level of RGC preservation than eyes that received the GFP-MSCs only (RGC cell counts: BDNF-MSC-treated COH eyes, 112.2 ± 19.39 cells/section; GFP-MSC-treated COH eyes, 52.21 ± 11.54 cells/section; P = 0.01).

CONCLUSIONS

The authors have demonstrated that lentiviral-transduced BDNF-producing MSCs can survive in eyes with chronic hypertension and can provide retina and optic nerve functional and structural protection. Transplantation of BDNF-producing stem cells may be a viable treatment strategy for glaucoma.

Neuroinflammation in advanced canine glaucoma

PURPOSE

The pathophysiological events that occur in advanced glaucoma are not well characterized. The principal purpose of this study is to characterize the gene expression changes that occur in advanced glaucoma.

METHODS

Retinal RNA was obtained from canine eyes with advanced glaucoma as well as from healthy eyes. Global gene expression patterns were determined using oligonucleotide microarrays and confirmed by real-time PCR. The presence of tumor necrosis factor (TNF) and its receptors was evaluated by immunolabeling. Finally, we evaluated the presence of serum autoantibodies directed against retinal epitopes using western blot analyses.

RESULTS

We identified over 500 genes with statistically significant changes in expression level in the glaucomatous retina. Decreased expression levels were detected for large number of functional groups, including synapse and synaptic transmission, cell adhesion, and calcium metabolism. Many of the molecules with decreased expression levels have been previously shown to be components of retinal ganglion cells. Genes with elevated expression in glaucoma are largely associated with inflammation, such as antigen presentation, protein degradation, and innate immunity. In contrast, expression of many other pro-inflammatory genes, such as interferons or interleukins, was not detected at abnormal levels.

CONCLUSIONS

This study characterizes the molecular events that occur in the canine retina with advanced glaucoma. Our data suggest that in the dog this stage of the disease is accompanied by pronounced retinal neuroinflammation.

Functional and structural changes in a canine model of hereditary primary angle-closure glaucoma

PURPOSE

To characterize functional and structural changes in a canine model of hereditary primary angle-closure glaucoma.

METHODS

Intraocular pressure (IOP) was evaluated with tonometry in a colony of glaucomatous dogs at 8, 15, 18, 20, and 30 months of age. Retinal function was evaluated using electroretinography (scotopic, photopic, and pattern). Examination of anterior segment structures was performed using gonioscopy and high-frequency ultrasonography (HFU).

RESULTS

A gradual rise in IOP was observed with an increase in age: 8 months, 14 mm Hg (median value); 15 months, 15.5 mm Hg; 18 months, 17.5 mm Hg; 20 months, 24 mm Hg; 30 months, 36 mm Hg. Provocative testing with mydriatic agents (tropicamide and atropine 1%) caused significant increases in IOP (35% and 50%, respectively). HFU analysis showed complete collapse of iridocorneal angles by 20 months of age. Scotopic and photopic ERG analysis did not reveal significant deficits, but pattern ERG analysis showed significantly reduced amplitudes in glaucomatous dogs (glaucoma, 3.5 +/- 0.4 muV; control, 6.2 +/- 0.3 muV; P = 0.004; Student's t-test). Histologic analysis revealed collapse of the iridocorneal angle, posterior bowing of the lamina cribrosa, swelling and loss of large retinal ganglion cells, increased glial reactivity, and increased thickening of the lamina cribrosa.

CONCLUSIONS

Canine hereditary angle-closure glaucoma is characterized by a progressive increase in intraocular pressure, loss of optic nerve function, and retinal ganglion cell loss.

Brain-derived neurotrophic factor released from engineered mesenchymal stem cells attenuates glutamate- and hydrogen peroxide-mediated death of staurosporine-differentiated RGC-5 cells

The purpose of this study was to determine the viability of cell-based delivery of brain-derived neurotrophic factor (BDNF) from genetically modified mesenchymal stem cells (MSCs) for neuroprotection of RGC-5 cells. RGC-5 cells were differentiated with the protein kinase inhibitor staurosporine (SS) and exposed to the cellular stressors glutamate or H2O2. As a neuroprotective strategy, these cells were then co-cultured across a membrane insert with mesenchymal stem cells (MSCs) engineered with a lentiviral vector for production of BDNF (BDNF-MSCs). As a positive control, recombinant human BDNF (rhBDNF) was added to stressed RGC-5 cells. After SS-differentiation RGC-5s developed neuronal-like morphologies, and a significant increase in the proportion of RGC-5s immunoreactive for TuJ-1 and Brn3a was observed. Differentiated RGC-5s also had prominent TrkB staining, demonstrating expression of the high-affinity BDNF receptor. Treatment of SS-differentiated RGC-5s with glutamate or H2O2, produced significant cell death (56.0 +/- 7.02 and 48.90 +/- 4.58% of control cells, respectively) compared to carrier-solution treated cells. BDNF-delivery from MSCs preserved more RGC-5 cells after treatment with glutamate (80.0 +/- 5.40% cells remaining) than control GFP expressing MSCs (GFP-MSCs, 57.29 +/- 1.89%, p < 0.01). BDNF-MSCs also protected more RGC-5s after treatment with H2O2 (65.6 +/- 3.47%) than GFP-MSCs (46.0 +/- 4.20%, p < 0.01). We have shown survival of differentiated RGC-5s is reduced by the cellular stressors glutamate and H2O2. Additionally, our results demonstrate that genetically modified BDNF-producing MSCs can enhance survival of stressed RGC-5 cells and therefore, may be effective vehicles to deliver BDNF to retinal ganglion cells affected by disease.

Integrins contribute to initial morphological development and process outgrowth in rat adult hippocampal progenitor cells

Adult rat hippocampal progenitor cells (AHPCs) are self-renewing, multipotent neural progenitor cells (NPCs) that can differentiate into neurons, oligodendrocytes, and astrocytes. AHPCs contact a variety of molecular cues within their surrounding microenvironment via integrins. We hypothesize that integrin receptors are important for NPCs. In this study, we have examined the distribution of integrins in neuronal-like, oligodendrocyte-like, and astrocyte-like AHPCs when grown on substrates that support integrin-mediated adhesion (laminin, fibronectin), and those that do not (poly-L: -ornithine, PLO) using immunocytochemistry as well as characterized the phenotypic differentiation of AHPCs plated on laminin and fibronectin. Focal adhesions were prominent in AHPCs plated on purified substrates, but were also found in AHPCs plated on PLO. The focal adhesions observed in AHPCs plated on PLO substrates may be formed by self-adhesion to the endogenously produced laminin or fibronectin. We have demonstrated that integrins contribute to the initial morphological differentiation of AHPCs, as inhibition of fibronectin binding with the competitive inhibitor echistatin significantly decreased the number of processes and microspikes present in treated cells, and also decreased overall cell area. Finally, we have characterized the genetic profile of a subset of integrins and integrin-related genes in the AHPCs using reverse transcriptase polymerase chain reaction. These results demonstrate an important role of integrins, in vitro, for the initial morphological differentiation of AHPCs.

Transplantation of Neural Progenitor Cells into the Developing Retina of the Brazilian Opossum: An in vivo System for Studying Stem/Progenitor Cell Plasticity

In developing cell transplant strategies to repair the diseased or injured retina is essential to consider host-graft interactions and how they may influence the outcome of the transplants. In the present study we evaluated the influence of the host microenvironment upon neural progenitor cells (NPCs) transplanted into the developing and mature retina of the Brazilian opossum, Monodelphis domestica. Monodelphis pups are born in an extremely immature state and the neonatal pups provide a fetal-like environment in which to study the interactions between host tissues and transplanted NPCs. Three different populations of GFP-expressing NPCs were transplanted by intraocular injection in hosts ranging in age from 5 days postnatal to adult. Extensive survival, differentiation and morphological integration of NPCs were observed within the developing retina. These results suggest that the age of the host environment can strongly influence NPC differentiation and integration.

[Average length of spontaneous labor in Chinese primigravidas]

OBJECTIVE

To determine if labor duration is affected by ethnicity, we measured the average length of normal spontaneous labor in recently immigrated Chinese primigravidas and compared our findings to reference primigravida populations of differing ethnicity.

MATERIALS AND METHODS

In this descriptive, retrospective study of 1,006 recently immigrated low-risk Chinese primigravidas delivering singleton, vertex, term infants (37-42 weeks gestation, inclusively) without conduction anesthesia or oxytocin, the length of first-, second-, and third-stage labor, maternal age, gestational age, and infant weight was measured and compared to labor lengths previously reported for women of differing ethnicity.

RESULTS

Mean first stage labor duration was 326 minutes (SD +/- 185 min, range 25-1640 min), mean second stage labor duration was 52 minutes (SD +/- 42 min, range 2-450 min), and a mean third stage labor duration was 4.6 min (SD +/- 4.5 min, range 1-62 min). Interquartile range (IQR)/median for first-, second-, and third-stage labor was 225 min/300 min, 50 min/40 min, and 3 min/3 min respectively. Weak correlations were observed between first- and second-stage labor lengths, and second- and third-stage labor lengths. Average birth weight was 3250 g (SD +/- 376 g, range 2280-4660 g). Chinese parturients showed a significantly shorter duration of first-stage (P < 0.0001) when compared to parity-matched patients of differing ethnicity. Second-stage labor in Chinese parturients was also shorter, but did not differ significantly (P = 0.185) from previously reported non-Asian controls.

CONCLUSION

When compared to previously collected data from non-Chinese women, clinically significant differences in first-stage labor lengths were measured in our study population. While second-stage labor durations were also shorter, the difference was not significant. Labor management should be individualized to account for these differences, and previous reports attempting to show equivalency of labor progress regardless of ethnicity warrant reinterpretation given these findings.

T and B lymphocytes play a minor role in atherosclerotic plaque formation in the apolipoprotein E-deficient mouse

Cellular and humoral immunity have been implicated in the pathogenesis of atherosclerosis. To determine whether an intact immune system is necessary for the formation of atherosclerotic lesions, we have generated immunodeficient mice with hypercholesterolemia and atherosclerosis by crossbreeding the apolipoprotein E (apoE)-deficient mouse with the recombinase activating gene 1 (Rag-1) knockout mouse. Chow-fed immunodeficient mice with targeted disruption in both apoE and Rag-1 (E0/R0) had a 2-fold decrement in aortic root lesion size at 16 weeks of age, compared with immunocompetent littermates, which were heterozygotes at the Rag-1 locus (E0/R1). Nearly all atherosclerotic lesions from chow-fed animals were limited to raised foam cell fatty streaks. In contrast, when a second group of animals was fed a high-fat Western-type diet to accelerate lesion development, there were no differences in either aortic root lesion size or the percent of the total aorta occupied by lesions. Fibrous plaques with well-defined caps and necrotic cores were detected in both Western diet-fed E0/R0 and E0/R1 animals. We conclude that T and B lymphocytes play only a minor role in the rate of forming foam cell lesions, and they are not necessary for the formation of fibroproliferative plaques.

Preliminary crystallographic study of the Fab fragment of a monoclonal anti-phenylarsonate antibody

Preliminary crystallographic data are given for the Fab fragment of a monoclonal anti-p-phenylarsonate antibody. This crystalline Fab fragment was found by screening a number of monoclonal anti-arsonate antibodies obtained from hybrids of A/J immune spleen cells with a non-secreting mouse myeloma line. The protein crystallizes in the monoclinic space group P21 with a = 86.2 +/- 0.1 A, b = 80.4 +/- 0.2 A, c = 75.8 +/- 0.1 A, beta = 90.3 +/- 0.1 degrees. Precession photographs show X-ray reflections extending to a resolution of 3 A.