Distinct subpopulations of ventral pallidal cholinergic projection neurons encode valence of olfactory stimuli.

To better understand the function of cholinergic projection neurons in the ventral pallidum (VP), we examined behavioral responses to appetitive (APP) and aversive (AV) odors that elicited approach or avoidance, respectively. Exposure to each odor increased cFos expression and calcium signaling in VP cholinergic neurons. Activity and Cre-dependent viral vectors selectively labeled VP cholinergic neurons that were activated and reactivated in response to either APP or AV odors, but not both, identifying two non-overlapping populations of VP cholinergic neurons differentially activated by the valence of olfactory stimuli. These two subpopulations showed differences in electrophysiological properties, morphology, and projections to the basolateral amygdala. Although VP neurons are engaged in both approach and avoidance behavioral responses, cholinergic signaling is only required for approach behavior. Thus, two distinct subpopulations of VP cholinergic neurons differentially encode valence of olfactory stimuli and play distinct roles in approach and avoidance behaviors.

Functionally refined encoding of threat memory by distinct populations of basal forebrain cholinergic projection neurons.

Neurons of the basal forebrain nucleus basalis and posterior substantia innominata (NBM/SIp) comprise the major source of cholinergic input to the basolateral amygdala (BLA). Using a genetically encoded acetylcholine (ACh) sensor in mice, we demonstrate that BLA-projecting cholinergic neurons can 'learn' the association between a naive tone and a foot shock (training) and release ACh in the BLA in response to the conditioned tone 24 hr later (recall). In the NBM/SIp cholinergic neurons express the immediate early gene, Fos following both training and memory recall. Cholinergic neurons that express Fos following memory recall display increased intrinsic excitability. Chemogenetic silencing of these learning-activated cholinergic neurons prevents expression of the defensive behavior to the tone. In contrast, we show that NBM/SIp cholinergic neurons are not activated by an innately threatening stimulus (predator odor). Instead, VP/SIa cholinergic neurons are activated and contribute to defensive behaviors in response to predator odor, an innately threatening stimulus. Taken together, we find that distinct populations of cholinergic neurons are recruited to signal distinct aversive stimuli, demonstrating functionally refined organization of specific types of memory within the cholinergic basal forebrain of mice.

Functionally refined encoding of threat memory by distinct populations of basal forebrain cholinergic projection neurons.

Neurons of the basal forebrain nucleus basalis and posterior substantia innominata (NBM/SIp) comprise the major source of cholinergic input to the basolateral amygdala (BLA). Using a genetically-encoded acetylcholine (ACh) sensor in mice, we demonstrate that BLA-projecting cholinergic neurons can "learn" the association between a naïve tone and a foot shock (training) and release ACh in the BLA in response to the conditioned tone 24h later (recall). In the NBM/SIp cholinergic neurons express the immediate early gene, Fos following both training and memory recall. Cholinergic neurons that express Fos following memory recall display increased intrinsic excitability. Chemogenetic silencing of these learning-activated cholinergic neurons prevents expression of the defensive behavior to the tone. In contrast, we show that NBM/SIp cholinergic neurons are not activated by an innately threatening stimulus (predator odor). Instead, VP/SIa cholinergic neurons are activated and contribute to defensive behaviors in response to predator odor, an innately threatening stimulus. Taken together, we find that distinct populations of cholinergic neurons are recruited to signal distinct aversive stimuli, demonstrating functionally refined organization of specific types of memory within the cholinergic basal forebrain of mice.

Loss of cholinergic input to the entorhinal cortex is an early indicator of cognitive impairment in natural aging of humans and mice.

In a series of translational experiments using fully quantitative positron emission tomography (PET) imaging with a new tracer specific for the vesicular acetylcholine transporter ([18F]VAT) in vivo in humans, and genetically targeted cholinergic markers in mice, we evaluated whether changes to the cholinergic system were an early feature of age-related cognitive decline. We found that deficits in cholinergic innervation of the entorhinal cortex (EC) and decline in performance on behavioral tasks engaging the EC are, strikingly, early features of the aging process. In human studies, we recruited older adult volunteers that were physically healthy and without prior clinical diagnosis of cognitive impairment. Using [18F]VAT PET imaging, we demonstrate that there is measurable loss of cholinergic inputs to the EC that can serve as an early signature of decline in EC cognitive performance. These deficits are specific to the cholinergic circuit between the medial septum and vertical limb of the diagonal band (MS/vDB; CH1/2) to the EC. Using diffusion imaging, we further demonstrate impaired structural connectivity in the tracts between the MS/vDB and EC in older adults with mild cognitive impairment. Experiments in mouse, designed to parallel and extend upon the human studies, used high resolution imaging to evaluate cholinergic terminal density and immediate early gene (IEG) activity of EC neurons in healthy aging mice and in mice with genetic susceptibility to accelerated accumulation amyloid beta plaques and hyperphosphorylated mouse tau. Across species and aging conditions, we find that the integrity of cholinergic projections to the EC directly correlates with the extent of EC activation and with performance on EC-related object recognition memory tasks. Silencing EC-projecting cholinergic neurons in young, healthy mice during the object-location memory task impairs object recognition performance, mimicking aging. Taken together we identify a role for acetylcholine in normal EC function and establish loss of cholinergic input to the EC as an early, conserved feature of age-related cognitive decline in both humans and rodents.

Deciphering Intermediate Nugent scores: Utility of Real-time PCR for Bacterial Vaginosis diagnosis.

PURPOSE: To optimize real-time PCR assays for diagnosis of Bacterial Vaginosis (BV) and determine cut-off loads by ROC analysis for Gardnerella vaginalis, Atopobium vaginae and Lactobacillus spp. as compared to Nugent scoring (Gold standard) in clinical samples. RESULTS: Out of 125 women, 34 were positive, 26 intermediate and 65 negative for BV by Nugent scoring. All three real-time PCR assays were found to be highly sensitive & specific and AUC suggested excellent diagnostic accuracy. An optimal cut-off was >9.45 × 103 copies/ ml, >3.34 × 103 copies/ ml & ≤ 18.63 × 103 copies/ ml for G. vaginalis, A. vaginae and Lactobacillus spp. respectively, in BV positives. Gram staining and qPCR were discordant only in patients with intermediate scores (n = 26) where qPCR identified 15 (57.69%) as positive and 11 (42.3%) as negative. CONCLUSION: PCR-based molecular BV diagnosis is more accurate and can be used for deciphering intermediate Nugent scores.

Bioactivation of an orthodontic wire using multifunctional nanomaterials to prevent plaque accumulation.

Controlling the growth of biofilm on orthodontic material has become a difficult challenge in modern dentistry. The antibacterial efficacy of currently used orthodontic material becomes limited due to the higher affinity of oral microbial flora for plaque formation on the material surface. Thus it is crutial to device an efficient strategy to prevent plaque buildup caused by pathogenic microbiota. In this work, we have fabricated a bioactive orthodontic wire using titanium nanoparticles (TiO2NPs) and silver nanoparticles (AgNPs). AgNPs were synthesized from the extracts of Ocimum sanctum, Ocimum tenuiflorum, Solanum surattense, and Syzygium aromaticum, while the TiO2NPs were synthesized by the Sol-Gel method. The nanoparticles were characterized by various biophysical techniques. The surface of the dental wire was molded by functionalizing these AgNPs followed by an additional coating of TiO2NPs. Functionalized dental wires were found to counteract the formation of tenacious intraoral biofilm, and showed an enhanced anti-bacterial effect against Multi-Drug Resistant (MDR) bacteria isolated from patients with various dental ailments. Data revealed that such surface coating counteracts the bacterial pathogens by inducing the leakage of Ag ions which eventually disrupts the cell membrane as confirmed from TEM micrographs. The results offer a significant opportunity for innovations in developing nanoparticle-based formulations to modify or fabricate an effective orthodontic material.

Basal forebrain cholinergic signalling: development, connectivity and roles in cognition.

Acetylcholine plays an essential role in fundamental aspects of cognition. Studies that have mapped the activity and functional connectivity of cholinergic neurons have shown that the axons of basal forebrain cholinergic neurons innervate the pallium with far more topographical and functional organization than was historically appreciated. Together with the results of studies using new probes that allow release of acetylcholine to be detected with high spatial and temporal resolution, these findings have implicated cholinergic networks in 'binding' diverse behaviours that contribute to cognition. Here, we review recent findings on the developmental origins, connectivity and function of cholinergic neurons, and explore the participation of cholinergic signalling in the encoding of cognition-related behaviours.

In vivo serotonin 1A receptor hippocampal binding potential in depression and reported childhood adversity.

BACKGROUND: Reported childhood adversity (CA) is associated with development of depression in adulthood and predicts a more severe course of illness. Although elevated serotonin 1A receptor (5-HT1AR) binding potential, especially in the raphe nuclei, has been shown to be a trait associated with major depression, we did not replicate this finding in an independent sample using the partial agonist positron emission tomography tracer [11C]CUMI-101. Evidence suggests that CA can induce long-lasting changes in expression of 5-HT1AR, and thus, a history of CA may explain the disparate findings. METHODS: Following up on our initial report, 28 unmedicated participants in a current depressive episode (bipolar n = 16, unipolar n = 12) and 19 non-depressed healthy volunteers (HVs) underwent [11C]CUMI-101 imaging to quantify 5-HT1AR binding potential. Participants in a depressive episode were stratified into mild/moderate and severe CA groups via the Childhood Trauma Questionnaire. We hypothesized higher hippocampal and raphe nuclei 5-HT1AR with severe CA compared with mild/moderate CA and HVs. RESULTS: There was a group-by-region effect (p = 0.011) when considering HV, depressive episode mild/moderate CA, and depressive episode severe CA groups, driven by significantly higher hippocampal 5-HT1AR binding potential in participants in a depressive episode with severe CA relative to HVs (p = 0.019). Contrary to our hypothesis, no significant binding potential differences were detected in the raphe nuclei (p-values > 0.05). CONCLUSIONS: With replication in larger samples, elevated hippocampal 5-HT1AR binding potential may serve as a promising biomarker through which to investigate the neurobiological link between CA and depression.

Endemic Chromoblastomycosis Caused Predominantly by Fonsecaea nubica, Madagascar1.

Chromoblastomycosis is an implantation fungal infection. Twenty years ago, Madagascar was recognized as the leading focus of this disease. We recruited patients in Madagascar who had chronic subcutaneous lesions suggestive of dermatomycosis during March 2013-June 2017. Chromoblastomycosis was diagnosed in 50 (33.8%) of 148 patients. The highest prevalence was in northeastern (1.47 cases/100,000 persons) and southern (0.8 cases/100,000 persons) Madagascar. Patients with chromoblastomycosis were older (47.9 years) than those without (37.5 years) (p = 0.0005). Chromoblastomycosis was 3 times more likely to consist of leg lesions (p = 0.003). Molecular analysis identified Fonsecaea nubica in 23 cases and Cladophialophora carrionii in 7 cases. Of 27 patients who underwent follow-up testing, none were completely cured. We highlight the persistence of a high level of chromoblastomycosis endemicity, which was even greater at some locations than 20 years ago. We used molecular tools to identify the Fonsecaea sp. strains isolated from patients as F. nubica.

Examining the underpinnings of loudness dependence of auditory evoked potentials with positron emission tomography.

Loudness dependence of auditory evoked potentials (LDAEP) has long been considered to reflect central basal serotonin transmission. However, the relationship between LDAEP and individual serotonin receptors and transporters has not been fully explored in humans and may involve other neurotransmitter systems. To examine LDAEP's relationship with the serotonin system, we performed PET using serotonin-1A (5-HT1A) imaging via [11C]CUMI-101 and serotonin transporter (5-HTT) imaging via [11C]DASB on a mixed sample of healthy controls (n â€‹= â€‹4: 4 females, 0 males), patients with unipolar (MDD, n â€‹= â€‹11: 4 females, 7 males) and bipolar depression (BD, n â€‹= â€‹8: 4 females, 4 males). On these same participants, we also performed electroencephalography (EEG) within a week of PET scanning, using 1000 â€‹Hz tones of varying intensity to evoke LDAEP. We then evaluated the relationship between LDAEP and 5-HT1A or 5-HTT binding in both the raphe (5-HT1A)/midbrain (5-HTT) areas and in the temporal cortex. We found that LDAEP was significantly correlated with 5-HT1A positively and with 5-HTT negatively in the temporal cortex (p â€‹< â€‹0.05), but not correlated with either in midbrain or raphe. In males only, exploratory analysis showed multiple regions in which LDAEP significantly correlated with 5-HT1A throughout the brain; we did not find this with 5-HTT. This multimodal study partially validates preclinical models of a serotonergic influence on LDAEP. Replication in larger samples is necessary to further clarify our understanding of the role of serotonin in perception of auditory tones.

Repair and remodelling in the shells of the limpet Patella vulgata.

Limpets and other molluscs rely on shells to protect them from physical damage, predation, dehydration, etc. If the shell becomes damaged, this may significantly impair its function. In this work, experiments were carried out to investigate the effect of damage on the strength of shells of the common limpet (Patella vulgata) and their ability to repair this damage effectively. Shells were damaged in three ways: (i) low-energy impacts; (ii) abrasion of the outer layer; and (iii) creation of a small hole in the apex of the shell. Shells were left to repair for several time periods (0, 10, 30 and 60 days). The mechanical strength was evaluated by impacting the shells with a weight dropped from a known height. The damage reduced the strength (defined as impact energy to failure) by 50-70% depending on damage type. After 60 days, limpets in all three groups had repaired their shells significantly, bringing their strength to 79-91% of the control value (in each case, samples were statistically indistinguishable from their control counterparts). Measurements of the thickness of the shell at the apex suggest that the main effect of low-energy impact and abrasion is reduction in thickness, which correlates linearly with the impact energy needed for failure. The method of repair is believed to be by the growth of fresh shell material on the inside of the shell, though we could not identify this new material specifically. Even after 60 days, the shells were still statistically thinner than the controls. Consequently, there may be some other strengthening mechanism at work. This work has demonstrated the remarkable ability of limpets to detect the mechanical weakening of their shells caused by relatively subtle forms of damage and to take appropriate action to restore shell strength.

Study Model-based Evaluation of Built-in Tip, Torque, and In-out Characteristics of a Third-generation Preadjusted Edgewise Appliance.

AIM: The aim of the study was to evaluate the clinical effectiveness of MBT™ preadjusted edgewise appliance (PEA) in terms of achieving the optimal expression of its built-in characteristics of tip, torque, and in-out. MATERIALS AND METHODS: Pretreatment and posttreatment study models of 20 subjects who received full fixed appliance treatment involving four first premolar extractions using the MBT™ appliance were measured for tip, torque, and in-out using the method described by Andrews. Treatment changes were analyzed statistically, and the posttreatment measurements were compared with the MBT™ specifications as well as Andrews' values for the above-mentioned parameters. RESULTS: Except for the maxillary canines and second premolars, the built-in tip of MBT™ appliance was nearly fully expressed, though there was some lack of correlation with Andrews' values. Despite the fact that the full amount of torque built into the MBT™ appliance was not expressed, torque measurements for all teeth except the maxillary second premolars and the first molars showed either no statistically significant difference or were significantly higher than Andrews' values for these teeth. In-out readings were lower than both MBT™ and Andrews' values, but the relative order of crown prominences was similar. Conclusion and clinical significance: The MBT™ appliance is thus effective in ensuring a successful treatment result, though individual adjustments may be necessary for optimal tooth positioning at the end of the treatment, as with any preadjusted appliance.

Decreased Pretreatment Amygdalae Serotonin Transporter Binding in Unipolar Depression Remitters: A Prospective PET Study.

Major depressive disorder (MDD) is a debilitating condition that affects over 14 million Americans. Remission occurs only in a minority of individuals after first-line antidepressant treatment (∼35%); predictors of treatment outcome are therefore needed. Using PET imaging with a radiotracer specific for the serotonin transporter (5-HTT), 11C-McN5652, we found that patients with MDD who did not achieve remission after 12 mo of naturalistic treatment had lower pretreatment midbrain and amygdala binding than healthy volunteers. Here, using a superior 5-HTT tracer, 11C-DASB, we repeated this study with a prospective design with 8 wk of standardized treatment with escitalopram. As this same cohort also underwent 11C-WAY100635 scans (serotonin-1A receptor [5-HT1A]), we examined whether using both pretreatment 5-HTT and 5-HT1A binding could improve prediction of posttreatment remission status. Methods: Thirty-one healthy controls (Hamilton Depression Rating Scale-24 item [HDRS-24] = 1.7) and 26 medication-free patients with MDD (HDRS-24 = 24.8) underwent PET scanning using 11C-DASB. MDD subjects then received 8 wk of standardized pharmacotherapy with escitalopram. The relationship between pretreatment binding and posttreatment clinical status was examined. Arterial blood samples were collected to calculate the metabolite-corrected arterial input function. The outcome measure was VT/fP (VT is volume of distribution in region of interest, fP is free fraction in plasma). Remission was defined as a posttreatment depression score of less than 10 as well as 50% or more reduction in the score from baseline, resulting in 14 nonremitters (HDRS-24 = 17.6) and 12 remitters (HDRS-24 = 5.3). Results: A linear mixed-effects model comparing group differences in the a priori regions of interest (amygdala and midbrain) revealed a significant difference in amygdala binding between controls and remitters (P = 0.03, unadjusted), where remitters had an 11% lower amygdala binding than controls. Differences in amygdala binding between remitters and nonremitters approached significance (P = 0.06). No additional differences were found between any groups (all P > 0.05). Additionally, we found no relationship between pretreatment amygdala binding and posttreatment depression score, and were unable to predict posttreatment depression severity using both pretreatment 5-HTT (in the amygdala) and 5-HT1A binding (in the raphe). Conclusion: These results suggest 5-HTT amygdala binding should be examined further, in conjunction with other measures, as a potential biomarker for remission after standardized escitalopram treatment.

Connexin 43 gene expression in mice with cardiopulmonary developmental defects.

Gap junctions are vital for cellular integrity, including homeostasis, morphogenesis, differentiation and growth in normal development of organs such as heart. Connexin 43 (Cx43) is a major gap junction protein. Our cDNA microarray analysis of normal and nitrofen-exposed neonatal mice with hypoplastic lungs, associated congenital diaphragmatic hernia (CDH) and heart developmental defects showed up-regulation of Cx43. Our objective was to establish if cardiopulmonary defects in nitrofen-exposed mice may be linked to altered expression of the Cx43 gene. We addressed our objective by performing northern blot analysis, real-time RT-PCR, immunoblotting and immunohistochemistry by localizing Cx43 in hearts and lungs of normal and nitrofen-exposed mice at different gestational stages. The data confirmed up-regulation of Cx43 expression in both hearts and lungs of CDH neonate mice and in lungs at other developmental stages except the pseudoglandular stage. However, Cx43 protein levels were either the same or less in hearts and lungs of nitrofen-exposed mice than in normal tissues except in pseudoglandular lungs. Different expressions of mRNA and protein suggest possible post-transcriptional or translational defects in Cx43. We observed dysmorphic hearts with exaggerated interventricular grooves and deep notches at the apex of the hearts in nitrofen-exposed fetal/neonatal mice; narrowed pulmonary out-flow and various degrees of craniofacial defects in 15-20% of the affected mice. Our data suggest a possible involvement of Cx43 in craniofacial, heart and lung defects in nitrofen-exposed mice. Such cardiopulmonary defects are also observed in human newborns with CDH. Thus, the murine data may help elucidate the pathways of cardiopulmonary defects in the human newborn condition.

Relevance of tenascin-C and matrix metalloproteinases in vascular abnormalities in murine hypoplastic lungs.

BACKGROUND: Tenascin-C (TN-C), an extracellular matrix glycoprotein, is crucial to cell-migration, proliferation, apoptosis and remodeling of tissues, with a potential role in pathobiology of pulmonary hypertension. Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) are crucial to the integrity of the extracellular matrix. TN-C and MMPs are counter-regulatory molecules, which influence the vascular integrity through modulations of elastin. We have a murine model of pulmonary hypoplasia with coexistent diaphragmatic hernia, vascular abnormalities and excessive arterial smooth muscle cell (SMC) proliferation. OBJECTIVES: Our objective was to investigate modulations of TN-C and MMPs in hypoplastic lungs and their possible contribution to the observed pulmonary vascular abnormalities. METHODS: We addressed our objectives by pursing immunoblotting and immunohistochemistry and zymography/reverse zymography to assess the alterations in activities of MMPs and their inhibitors. RESULTS: We observed significant down-regulation of MMP-9 activity in hypoplastic lungs at the later fetal developmental stages, whereas MMP-2 activity assessed by gelatin zymography remained unaltered. Reverse zymography revealed up-regulation of activities of TIMP-1, -2, -3 and -4 in hypoplastic lungs during later fetal development, with pronounced increases in TIMP-3 and -4 activities. Furthermore, immunoblot analyses and immunohistochemistry revealed that TN-C protein was down-regulated in developing hypoplastic lungs, compared to normal lungs. CONCLUSIONS: (1)TN-C is known to inhibit vascular SMC proliferation. But, decrease in TN-C in hypoplastic lungs may support the observed arterial SMC proliferation. (2) Our studies showed that in hypoplastic lungs the SMC apoptosis is not affected, thus suggesting that SMC proliferation and apoptosis may be two separate processes in pulmonary hypoplasia with coexistent diaphragmatic hernia. Together, our data showed an imbalance in the extracellular matrix proteins, which may contribute to the pulmonary vascular abnormalities.

Expression profile of IGF system during lung injury and recovery in rats exposed to hyperoxia: a possible role of IGF-1 in alveolar epithelial cell proliferation and differentiation.

Although several studies have shown that an induction of insulin-like growth factor (IGF) components occurs during hyperoxia-mediated lung injury, the role of these components in tissue repair is not well known. The present study aimed to elucidate the role of IGF system components in normal tissue remodeling. We used a rat model of lung injury and remodeling by exposing rats to > 95% oxygen for 48 h and allowing them to recover in room air for up to 7 days. The mRNA expression of IGF-I, IGF-II, and IGF-1 receptor (IGF-1R) increased during injury. However, the protein levels of these components remained elevated until day 3 of the recovery and were highly abundant in alveolar type II cells. Among IGF binding proteins (IGFBPs), IGFBP-5 mRNA expression increased during injury and at all the recovery time points. IGFBP-2 and -3 mRNA were also elevated during injury phase. In an in vitro model of cell differentiation, the expression of IGF-I and IGF-II increased during trans-differentiation of alveolar epithelial type II cells into type-I like cells. The addition of anti-IGF-1R and anti-IGF-I antibodies inhibited the cell proliferation and trans-differentiation to some extent, as evident by cell morphology and the expression of type I and type II cell markers. These findings demonstrate that the IGF signaling pathway plays a critical role in proliferation and differentiation of alveolar epithelium during tissue remodeling.

Persistent vascular defects in lung allografts attributed to defective endogenous endothelial progenitors.

BACKGROUND: A major pathological finding in human newborns with pulmonary hypoplasia and congenital diaphragmatic hernia is the presence of vascular abnormalities in lungs. Vasculogenesis/angiogenesis are crucial to lung development. To study lung alveolar development, including microvascular formation in fetal lung implants, Schwarz et al. [1] developed a subcutaneous allograft model. We adopted their model to assess the influence of neovascularization or the "host-graft vascular development" on hypoplastic lung structure and growth. MATERIALS AND METHODS: Normal and hypoplastic lungs at pseudoglandular stage were implanted subcutaneously under the dorsolateral fold of immunocompromised nude mice (athymic, nu/nu). Lung allografts were removed and assessed at 2, 4, 6, and 8 weeks postimplantation. RESULTS: Neovascularization of implanted lungs from subcutaneous vasculature of nude mice resulted in varying degrees of maturation of implanted normal and hypoplastic lungs. By 4 weeks, implanted normal lungs contained Type 2-like cells and by 7 to 8 weeks, Type 2 and Type 1-like cells, air spaces had enlarged, and surfactant secretion was observed. Despite some differentiation and maturation of hypoplastic lungs, there was more mesenchymal tissue, no secondary septa, and smaller air spaces compared to normal lungs. CONCLUSIONS: (a) Neovascularization or host-graft vascular development occurs in both normal and hypoplastic lung allografts. (b) Development and maturation of implanted normal and hypoplastic lungs follow the establishment of the vascular connections between the host and grafts. (c) The host-graft vascular connections do not improve the growth of normal or hypoplastic lungs. (d) Neovascularization failed to overcome the embryonic defects in vascular formation and the pulmonary vasculogenesis remained defective in hypoplastic lung allografts, which may be attributed to the defective endogenous endothelial progenitor cells.

Basic science faculty in surgical departments: advantages, disadvantages and opportunities.

The number of Ph.D. faculty in clinical departments now exceeds the number of Ph.D. faculty in basic science departments. Given the escalating pressures on academic surgeons to produce in the clinical arena, the recruitment and retention of high-quality Ph.D.s will become critical to the success of an academic surgical department. This success will be as dependent on the surgical faculty understanding the importance of the partnership as the success of the Ph.D. investigator. Tighter alignment among the various clinical and research programs and between surgeons and basic scientists will facilitate the generation of new knowledge that can be translated into useful products and services (thus improving care). To capitalize on what Ph.D.s bring to the table, surgery departments may need to establish a more formal research infrastructure that encourages the ongoing exchange of ideas and resources. Physically removing barriers between the research groups, encouraging the open exchange of techniques and observations and sharing core laboratories is characteristic of successful research teams. These strategies can meaningfully contribute to developing successful training program grants, program projects and bringing greater research recognition to the department of surgery.

Thyroid hormone affects distal airway formation during the late pseudoglandular period of mouse lung development.

We recently showed that T3 treatment of cultured gestational day 11.5 early pseudoglandular period mouse lungs, accelerated terminal airway development at the expense of decreased branching morphogenesis. As the ability of T3 to influence epithelial cell differentiation increases with advancing development, we hypothesized that in the late pseudoglandular period, T3 would cause further premature changes in the morphology of the distal airways leading to abnormal saccular development. Gestational day 13.5 embryonic mouse lungs were cultured for 3 and 7 days without or with added T3. Increasing T3 dose and time in culture resulted in progressive development of thin walled, abnormal saccules, an increase in cuboidal and flattened epithelia and airway space with a concomitant decrease in mesenchymal cell volume. Consistent with increased cuboidal and flattened epithelial cell volume identified by morphometry, immunostaining suggested increased cell proliferation detected by localization of proliferating cell nuclear antigen (PCNA) in epithelial cells of T3 treated lungs. T3 decreased mesenchymal expression of Hoxb-5 protein and caused progressive localization of Nkx2.1 and SP-C proteins to distal cuboidal epithelia of early abnormal saccules, evidence that T3 prematurely and abnormally advanced mesenchymal and epithelial cell differentiation. Western blot showed a T3-dependent decrease in Hoxb-5 and a trend towards decreased Nkx2.1 and SP-C, after 3 and 7 days of culture, respectively. We conclude that exogenous T3 treatment during the late pseudoglandular period prematurely and abnormally accelerates terminal saccular development. This may lead to abnormal mesenchymal and epithelial cell fate.