Factors associated with the change in prevalence of cardiomyopathy at delivery in the period 2000-2009: a population-based prevalence study.

OBJECTIVE: Cardiomyopathy (CM) at delivery is increasing in prevalance. The objective of this study was to determine which medical conditions are attributable to this increasing prevalance. DESIGN: Population prevalence study from 2000 to 2009. SETTING: The Nationwide Inpatient Sample (NIS). SAMPLE: Pregnant women admitted for delivery were identified in the NIS for the years 2000-2009. METHODS: Temporal trends in pre-existing medical conditions and in medical and obstetric complications at delivery admissions were determined by linear regression. The change in the prevalence of CM among all pregnant women was compared with the change in the prevalance of CM among pregnant women without pre-existing conditions or complications. MAIN OUTCOME MEASURE: Prevalence of CM. RESULTS: The prevalence of CM increased from 0.25 per 1000 deliveries in 2000 to 0.43 per 1000 deliveries in 2009 (P < 0.0001). Women with chronic hypertension had increased odds of developing CM compared with women without chronic hypertension (odds ratio, OR, 13.2; 95% confidence interval, 95% CI, 12.5-13.7). The linear increase in chronic hypertension over the 10-year period was the single identified pre-existing medical condition that explained the increasing prevalence of CM at delivery (P = 0.005 for the differences in slopes for linear trends). CONCLUSIONS: Pregnant women with chronic hypertenion are at an increased risk for CM at delivery, and the increasing prevalence of chronic hypertension is an important factor associated with the increasing prevalence of CM at the time of delivery. Among women without chronic hypertension, the prevalence of CM at delivery did not change during the time period.

Increased phasic dopamine signaling in the mesolimbic pathway during social defeat in rats.

While reward-dependent facilitation of phasic dopamine signaling is well documented at both the cell bodies and terminals, little is known regarding fast dopamine transmission under aversive conditions. Exposure to aggressive confrontation is extremely aversive and stressful for many species including rats. The present study used fast-scan cyclic voltammetry and multiunit recording to determine if aggressive encounters and subsequent social defeat affect burst firing of ventral tegmental area (VTA) dopamine neurons and accumbal dopamine transients in defeated rats. Significant increases in the frequency of transient dopamine release were observed during interactions with an aggressive rat but not with a familiar cage mate. In agreement with voltammetric results, significant increases in burst frequency were detected in the VTA dopamine firing patterns during an aggressive confrontation; however, the number of spikes per burst remained unchanged. We found that neurons with lower burst rates under home cage conditions did not switch from nonbursting to bursting types, while neurons with higher burst levels showed amplified increases in bursting. This study demonstrates for the first time that aggressive confrontations in defeated rats are associated with increases in phasic dopamine transmission in the mesolimbic pathway.

Central scalp alopecia photographic scale in African American women.

Central centrifugal cicatricial alopecia (CCCA) is a common but poorly understood cause of hair loss in African American women. A photographic scale was developed that captures the pattern and severity of the central hair loss seen with CCCA in order to help identify this problem in the general community and to potentially correlate clinical data with hair loss. The utility and reproducibility of this photographic scale was determined in a group of 150 African American women gathered for a health and beauty day who were evaluated by both four investigators experienced in the diagnosis of hair disorders and by the subjects themselves.

Effects of restraint and haloperidol on sensory gating in the midbrain of awake rats.

Deficits in sensory processing have been reported to be associated with an array of neuropsychiatric disorders including schizophrenia. Auditory sensory gating paradigms have been routinely used to test the integrity of inhibitory circuits hypothesized to filter sensory information. Abnormal dopaminergic neurotransmission has been implicated in the expression of schizophrenic symptoms. The aim of this study was to determine if inhibitory gating in response to paired auditory stimuli would occur in putative dopaminergic and non-dopaminergic midbrain neurons. A further goal of this study was to determine if restraint, a classic model of stress known to increase extracellular dopamine levels, and systemic haloperidol injections affected inhibitory mechanisms involved in sensory gating. Neural activity in the rat midbrain was recorded across paired auditory stimuli (first auditory stimulus (S1) and second auditory stimulus (S2)) under resting conditions, during restraint and after systemic haloperidol injections. Under resting conditions, a subset of putative GABA neurons showed fast, gated, short latency responses while putative dopamine neurons showed long, slow responses that were inhibitory and ungated. During restraint, gated responses in putative GABAergic neurons were decreased (increased S2/S1 or ratio of test to conditioning (T/C)) by reducing the response amplitude to S1. Systemic haloperidol decreased the T/C ratio by preferentially increasing response amplitude to S1. The results from this study suggest that individual neurons encode discrete components of the auditory sensory gating paradigm, that phasic midbrain GABAergic responses to S1 may trigger subsequent inhibitory filtering processes, and that these GABAergic responses are sensitive to restraint and systemic haloperidol.

Effect of zoledronic acid on pain associated with bone metastasis in patients with prostate cancer.

BACKGROUND: Zoledronic acid reduces skeletal-related events associated with prostate cancer and has long-term efficacy in pain outcomes. Findings of treatment group differences in pain early in treatment are less reliable. We used a recently recommended analytic approach to examine the effect of zoledronic acid on pain. MATERIALS AND METHODS: In a trial of zoledronic acid (n = 214) versus placebo (n = 208), we used the Brief Pain Inventory to assess pain at baseline, 3 weeks, 6 weeks and every 6 weeks thereafter for a total of 60 weeks. We used a modified longitudinal rank test to determine whether clinically meaningful changes in pain were related to treatment group. RESULTS: Seventy-six of 214 patients (35.5%) receiving zoledronic acid and 62 of 208 patients (29.8%) receiving placebo completed the 60-week visit (P = 0.22). In all 11 pain assessments, patients receiving zoledronic acid reported more favorable, clinically meaningful changes in pain scores. Overall, patients receiving zoledronic acid had a 33% chance of a favorable response, compared with 25% for patients receiving placebo (P = 0.04; 95% CI 0.5% to 15.6%). CONCLUSIONS: Zoledronic acid was more likely than placebo to be associated with clinically meaningful reductions in pain. Thus, zoledronic acid may help to avert the pain experienced by patients with progressing metastatic disease secondary to prostate cancer.

Effect of gender on the outcomes of contemporary percutaneous coronary intervention.

Limited information exists regarding the outcomes of newer percutaneous coronary intervention (PCI) technologies in women. This study sought to determine whether female gender is an independent risk factor for PCI mortality and/or complications in contemporary practice. Using information from the National Cardiovascular Network (NCN) Database on 109,708 (33% women) PCI cases from 22 hospitals between January 1994 and January 1998, we examined the association of gender with unadjusted and risk-adjusted procedural outcomes. Women undergoing PCI were older, smaller, and had more comorbid illness than men, but less extensive coronary disease. Temporal trends in PCI device selection were similar in men and women. Compared with men, women had higher unadjusted procedural mortality rates (1.8% vs 1.0%, p <0.001), more strokes (0.4% vs 0.2%, p <0.001), and higher vascular complication rates (5.4% vs 2.7%, p <0.001). However, after adjusting for baseline clinical risk factors, and importantly, body surface area, women and men had similar PCI mortality risks (adjusted odds ratio 1.07, 95% confidence interval 0.92 to 1.24). Gender was not an independent risk factor for mortality among subgroups receiving coronary stent or atherectomy devices after risk adjustment. However, women undergoing PCI remained at higher risk for stroke, vascular complications, and repeat in-hospital revascularization than men, even after risk adjustment. We conclude that in contemporary practice, a patient's body size rather than gender, conveys independent risk for mortality after PCI.

Assessing the clinical and economic burden of coronary artery disease: 1986-1998.

BACKGROUND: The acute phase of coronary artery disease (CAD) is dramatic and receives much attention because of its high mortality and associated treatment cost. However, the acute phase typically resolves within 30 days whereas CAD is a chronic disease, which most patients will live with for more than a decade. We compared the clinical and economic burden of CAD during the acute phase (first 30 days) with that in the postacute phase (31st day through 10 years). METHODS: We included acute coronary syndrome (ACS) patients with significant CAD receiving an initial cardiac catheterization at Duke University Medical Center between 1986 and 1997 with follow-up continuing through 1998. Inpatient medical costs were estimated from ACS clinical trial and economic study data. Costs were adjusted to 1997 values and discounted at 3% per annum. RESULTS: Our study included 9,876 ACS patients (5,557 with an acute myocardial infarction [MI] and 4,319 with unstable angina [UA]). Acute MI patients had higher 30-day mortality than UA patients (5.6% vs. 2.3%, P <0.001). In addition, acute MI and UA patients had significant 10-year unadjusted and adjusted survival differences (both P <0.001). For patients who survived to 30 days, there was no difference in 10-year survival between acute MI and UA patients before adjustment (P = 0.472). After adjustment, however, unstable angina patients who survived to 30 days had greater survival than myocardial infarction patients (P = 0.011). Mean 10-year discounted ACS inpatient medical costs were $45,253 ($23,510 acute phase and $21,819 postacute phase, P = 0.002). Ten year costs for unstable angina patients were $46,423 ($21,824 acute phase and $24,599 postacute phase, P = 0.003); ten year costs for myocardial infarction patients were $44,663 ($24,823 acute phase and $19,840 postacute phase, P <0.001). CONCLUSIONS: We found that the clinical and economic burden of CAD continues long after a patient's acute event has resolved and that postacute CAD cardiac event rates and inpatient medical costs may be higher than previously estimated. With much of all medical costs occurring in the postacute phase, the potential for effective secondary prevention therapies is substantial.

Alabama coronary artery bypass grafting project: results of a statewide quality improvement initiative.

CONTEXT: Efforts to improve quality of care in the cardiac surgery field have focused on reducing the risk-adjusted mortality associated with common surgical procedures, such as coronary artery bypass grafting (CABG). However, the best methodological approach to improvement is under debate. OBJECTIVE: To test an intervention to improve performance of CABG surgery. DESIGN AND SETTING: Quality improvement project based on baseline (July 1, 1995-June 30, 1996) and follow-up (July 1-December 31, 1998) performance measurements from medical record review for all 20 Alabama hospitals that provided CABG surgery. PATIENTS: Medicare patients discharged after CABG surgery in Alabama (n = 5784), a comparison state (n = 3214), and a national sample (n = 3758). INTERVENTION: Confidential hospital-specific performance feedback and assistance with multimodal improvement interventions, including the option to share relevant experience with peers. MAIN OUTCOME MEASURES: Duration of intubation, reintubation rate, aspirin therapy at discharge, use of the internal mammary artery (IMA), hospital readmission rate, and risk-adjusted in-hospital mortality. RESULTS: Proportion of extubation within 6 hours increased from 9% to 41% in Alabama, decreased from 40% to 39% in the comparison state, and increased from 12% to 25% in the national sample. Use of IMA increased from 73% to 84%, 48% to 55%, and 74% to 81%, respectively, in the 3 samples, but aspirin use increased only in Alabama (from 88% to 92%). The amount of improvement in all 3 of these process measures was greater in Alabama than in the other samples (IMA use for Alabama vs comparison state was P =.001 and for Alabama vs national sample, P =.02; and P<.001 for all other comparisons). Risk-adjusted mortality decreased in Alabama (4.9% to 2.9%), but this decrease was not statistically significantly different from mortality changes in the other groups (odds ratio, 0.76; 95% confidence interval, 0.54-1.07 vs national sample). CONCLUSION: Confidential peer-based regional performance feedback and process-oriented analysis of shared experience are associated with some improvement in quality of care for patients who underwent CABG surgery.

Association between selective serotonin-reuptake inhibitor therapy and heart valve regurgitation.

The identification of an association between fenfluramines and valvular disease has raised the possibility of a similar association between another class of medications that increases local levels of serotonin, the selective serotonin-reuptake inhibitors (SSRIs). The objective of this study was to examine the association between heart valve regurgitation and treatment with SSRIs. We examined 5,437 consecutive patients who underwent echocardiography. Patients with a similar likelihood of SSRI treatment were identified by propensity models. The prevalence of regurgitation according to treatment was compared after adjusting for clinical characteristics associated with regurgitation. We also blindly reinterpreted a subset of 2,000 echocardiograms to identify characteristics associated with fenfluramine-associated valvular heart disease such as posterior mitral leaflet restriction. Among 5,437 consecutively hospitalized patients, we identified 292 who had taken SSRIs before admission. Patients taking SSRIs tended to be younger, female, Caucasian, unmarried, and more likely to have psychiatric illness and hypertension (p < or = 0.05). The overall prevalence of regurgitation meeting Food and Drug Administration criteria (at least moderate mitral regurgitation or mild aortic regurgitation) was 30%, with no significant difference in prevalence between those receiving SSRIs (26.7%) and controls (30.4%) (p = 0.19). The association remained negative when comparing SSRI-treated patients to controls with similar characteristics. Furthermore, the prevalence of features described in conjunction with fenfluramine exposure, such as posterior mitral leaflet restriction, was not higher in SSRI-treated patients. Among a large consecutive cohort of patients, the prevalence of mitral and aortic regurgitation in patients taking SSRIs was not different from that of controls, suggesting that SSRIs are not associated with valvular disease.

The progression of fenfluramine-associated valvular heart disease assessed by echocardiography.

BACKGROUND: An association between the dietary suppressants fenfluramine and dexfenfluramine and valvular heart disease was first described in patients from North Dakota and Minnesota in 1997. Limited data are available on the natural history of this valvulopathy after discontinuation of drug therapy. OBJECTIVE: To follow the progression of fenfluramine-associated valvular heart disease after discontinuation of therapy by using serial echocardiography. DESIGN: Retrospective cohort study. SETTING: Regional medical center in Fargo, North Dakota. PATIENTS: 50 patients with previous exposure to fenfluramines who had at least mild mitral regurgitation or aortic regurgitation after exposure to fenfluramines on serial echocardiography between December 1994 and February 1999 (96% were female, mean body mass index was 36.6 kg/m(2), and mean duration of drug exposure was 447 days). MEASUREMENTS: Serial echocardiograms were reviewed by two echocardiographers who were blinded to the order of image acquisition. The severity of valvular regurgitation and presence or absence of valve leaflet restriction were assessed. RESULTS: As described in the initial report, significant valvular disease on initial postexposure echocardiography was common in this cohort; 38 patients (76%) had at least mild mitral regurgitation and 43 patients (86%) had at least mild aortic regurgitation. On serial echocardiograms obtained an average of 356 days apart, mitral regurgitation improved by at least one grade in 17 patients (P = 0.001) and aortic regurgitation improved by at least one grade in 19 patients (P = 0.004). Nineteen and 22 patients, respectively, experienced no change in severity of mitral and aortic regurgitation. Two patients in each group experienced worsening of regurgitation by at least one grade. Results were similar for tricuspid (P = 0.002) and pulmonic (P = 0.012) regurgitation. CONCLUSION: On serial echocardiography, fenfluramine-associated valvular regurgitation improved or remained stable in most patients after therapy ended. Worsening of valvular regurgitation was uncommon. The potential for stabilization or regression of valvular regurgitation should be taken into account when counseling patients and considering the need for and timing of valve surgery.

Distribution of the calcium-binding proteins calbindin D-28K and parvalbumin in the superior colliculus of adult and neonatal cat and rhesus monkey.

The distribution of the calcium-binding proteins calbindin D-28K and parvalbumin was examined in newborn and adult superior colliculus of cat and rhesus monkey using immunohistochemical techniques. In adult animals of both species, calbindin-immunoreactive neurons had a three-tiered arrangement: one band was present in the upper aspects of the superficial laminae, a second in the intermediate laminae, and a third in the deep laminae. The intermediate tier was less obvious in the monkey, whereas the deep tier was less pronounced in the cat. Parvalbumin-immunoreactive neurons had a complementary distribution to calbindin-immunoreactive neurons within these laminae in both species, although the segregation of calbindin immunoreactivity and parvalbumin immunoreactivity in the superficial laminae was not as precise in the monkey as it was in the cat. At birth, calbindin immunoreactivity in the newborns of both species was remarkably mature, with its three-tiered distribution clearly evident. By contrast, parvalbumin immunoreactivity was distinctly different in the newborn cat than in the newborn monkey: whereas parvalbumin immunoreactivity in the newborn monkey was already very similar to its adult-like pattern, the pattern in the newborn cat was quite immature. The superficial laminae of the newborn cat were virtually devoid of parvalbumin immunoreactivity, and, although the intermediate laminae displayed robust parvalbumin-immunoreactive neuropil, comparatively fewer parvalbumin-immunoreactive neurons were observed. Conspicuously few in number were the large multipolar neurons in the intermediate laminae, which give rise to the descending efferents to the brainstem. However, parvalbumin-immunoreactive neurons were present within the deep laminae, suggesting a ventral-to-dorsal maturational gradient in parvalbumin expression that parallels the ventral-to-dorsal gradient of neurogenesis. The differences in parvalbumin immunoreactivity observed between these two species at parturition are consistent with the advanced visual and visuomotor capabilities of the newborn monkey and the absence of visually related behaviors in the newborn cat.

Utilizing propensity scores to estimate causal treatment effects with censored time-lagged data.

Observational studies frequently are conducted to compare long-term effects of treatments. Without randomization, patients receiving one treatment are not guaranteed to be prognostically comparable to those receiving another treatment. Furthermore, the response of interest may be right-censored because of incomplete follow-up. Statistical methods that do not account for censoring and confounding may lead to biased estimates. This article presents a method for estimating treatment effects in nonrandomized studies with right-censored responses. We review the assumptions required to estimate average causal effects and derive an estimator for comparing two treatments by applying inverse weights to the complete cases. The weights are determined according to the estimated probability of receiving treatment conditional on covariates and the estimated treatment-specific censoring distribution. By utilizing martingale representations, the estimator is shown to be asymptotically normal and an estimator for the asymptotic variance is derived. Simulation results are presented to evaluate the properties of the estimator. These methods are applied to an observational data set of acute coronary syndrome patients from Duke University Medical Center to estimate the effect of a treatment strategy on the mean 5-year medical cost.

Contemporary outcome trends in the elderly undergoing percutaneous coronary interventions: results in 7,472 octogenarians. National Cardiovascular Network Collaboration.

OBJECTIVES: We sought to define the risks facing octogenarians undergoing contemporary percutaneous coronary interventions (PCIs). BACKGROUND: The procedural risks of PCI for octogenarians have not been well established. METHODS: We compared the clinical characteristics and in-hospital outcomes of 7,472 octogenarians (mean age 83 years) with those of 102,236 younger patients (mean age 62 years) who underwent PCI at 22 National Cardiovascular Network (NCN) hospitals from 1994 through 1997. RESULTS: Octogenarians had more comorbidities, more extensive coronary disease and a two- to fourfold increased risk of complications, including death (3.8% vs. 1.1%), Qwave myocardial infarction (1.9% vs. 1.3%), stroke (0.58% vs. 0.23%), renal failure (3.2% vs. 1.0%) and vascular complications (6.7% vs. 3.3%) (p < 0.001 for all comparisons). Independent predictors of procedural mortality in octogenarians included shock (odds ratio [OR] 5.4, 95% confidence interval [CI] 3.3 to 8.8), acute myocardial infarction (OR 3.2, 95% CI 2.3 to 4.4), left ventricular ejection fraction (LVEF) <35% (OR 2.9, 95% CI 2.1 to 3.9), renal insufficiency (OR 2.8, 95% CI 2.0 to 3.8), first PCI (OR 2.3, 95% CI 1.7 to 3.3), age >85 years (OR 2.1, 95% CI 1.5 to 2.7) and diabetes mellitus (OR 1.5, 95% CI 1.1 to 2.0). For elective procedures, octogenarian mortality varied nearly 10-fold, and was strongly influenced by comorbidities (0.79% mortality with no risk factors vs. 7.2% with renal insufficiency or LVEF <35%). Despite similar case-mix, PCI outcomes in octogenarians improved significantly over the four years of observation (OR of 0.61 for death/myocardial infarction/stroke in 1997 vs. 1994; 95% CI 0.45 to 0.85). CONCLUSIONS: Risks to octogenarians undergoing PCI are two- to fourfold higher than those of younger patients, strongly influenced by comorbidities, and have decreased in the stent era.

Outcomes of cardiac surgery in patients > or = 80 years: results from the National Cardiovascular Network.

OBJECTIVES: The purpose of this study was to evaluate characteristics and outcomes of patients age > or =80 undergoing cardiac surgery. BACKGROUND: Prior single-institution series have found high mortality rates in octogenarians after cardiac surgery. However, the major preoperative risk factors in this age group have not been identified. In addition, the additive risks in the elderly of valve replacement surgery at the time of bypass are unknown. METHODS: We report in-hospital morbidity and mortality in 67,764 patients (4,743 octogenarians) undergoing cardiac surgery at 22 centers in the National Cardiovascular Network. We examine the predictors of in-hospital mortality in octogenarians compared with those predictors in younger patients. RESULTS: Octogenarians undergoing cardiac surgery had fewer comorbid illnesses but higher disease severity and surgical urgency than younger patients. Octogenarians had significantly higher in-hospital mortality after cardiac surgery than younger patients: coronary artery bypass grafting (CABG) only (8.1% vs. 3.0%), CABG/aortic valve (10.1% vs. 7.9%), CABG/mitral valve (19.6% vs. 12.2%). In addition, they had twice the incidence of postoperative stroke and renal failure. The preoperative clinical factors predicting CABG mortality in the very elderly were quite similar to those for younger patients with age, emergency surgery and prior CABG being the powerful predictors of outcome in both age categories. Of note, elderly patients without significant comorbidity had in-hospital mortality rates of 4.2% after CABG, 7% after CABG with aortic valve replacement (CABG/AVR), and 18.2% after CABG with mitral valve replacement (CABG/MVR). CONCLUSIONS: Risks for octogenarians undergoing cardiac surgery are less than previously reported, especially for CABG only or CABG/AVR. In selected octogenarians without significant comorbidity, mortality approaches that seen in younger patients.

Evolving trends in interventional device use and outcomes: results from the National Cardiovascular Network Database.

BACKGROUND: Although multiple new coronary interventional devices have been approved for marketing in the United States, use of these technologies in general clinical practice and their associated outcomes have not been reported. METHODS AND RESULTS: Using the National Cardiovascular Network's Coronary Interventional Database, we examined temporal trends in the use and outcomes of coronary stents, lasers, directional atherectomy, and rotational atherectomy devices at 12 US hospitals between January 1994 and December 1997 (n = 76,904). Over this period, the percentage of cases involving coronary stents rose more than 12-fold (from 5.4% in 1994 to 69.0% in 1997). In contrast, use of atherectomy-type devices declined significantly. Device selection was strongly influenced by the patient's coronary anatomy and procedural indication, but less by age, sex, or race. Device use also varied significantly among individual centers (4-fold variation among sites in stent use and 6-fold variation in atherectomy use) even after adjusting for patient characteristics. Although overall mortality rates were unchanged during this 4-year period, procedural success rates have improved and complication rates have declined significantly. Lengths of postprocedure hospital stay also fell significantly for all patients undergoing coronary intervention in this time period. CONCLUSIONS: Percutaneous interventional strategies are rapidly changing with the explosive growth of coronary stent use and the decline in use of atherectomy devices. Patient outcomes, including complication rates and postprocedure lengths of stay, have also improved as the new interventional strategies have been refined in clinical practice.

Mesolimbic neuronal activity across behavioral states.

A goal of neurophysiology of the mesolimbic system is to determine the activity patterns within the regions in the prefrontal cortex, ventral neostriatum, and amygdala that regulate behavioral patterns to seek rewards. A new technology has been introduced in which arrays of microwires are implanted in different brain regions while activity patterns of ensembles of neurons are recorded for long periods of time during freely moving behaviors. Multichannel instrumentation and software is used for data acquisition and analysis. An initial hypothesis was that neural signals would be encountered in the nucleus accumbens and associated regions specifically related to reward. However, an initial study of neural activity and behavioral patterns during a simple lever press for intravenous cocaine (1 mg/kg) revealed that phasic excitatory or inhibitory neural activity patterns often appear prior to the reward phase. Individual neurons throughout the mesolimbic system appear to code information specific to sensory and motor events, tones, or lever presses in the chain of tasks leading to all rewards so far studied. Different spatial temporal patterns also appear within the same neural populations, as reward is changed from injected cocaine to heroin, from ingested pure water to ethanol in water or sucrose. Overall, patterns of activity for each neuron are found to shift dynamically during the operant task as changes are made in the target reward. Significant shifts in activity of mesolimbic neurons that are unrelated to specific sensory-motor events also appear during complex sessions, such as during a bout of ethanol consumption to reach satiation or during progressive ratio tasks with increasing difficulty. An emerging hypothesis is that some candidate neural elements in the mesolimbic system code the anticipated reward, whereas others serve internal logic functions of motivation that mediate extinction or resumption of specific goal-directed behaviors.

Tenascin-C lines the migratory pathways of avian primordial germ cells and hematopoietic progenitor cells.

Tenascin-C is a large hexameric extracellular matrix glycoprotein associated with epithelial-mesenchymal interactions, connective tissue development, and the formation of the central nervous system. Tenascin-C also lines the pathways followed by migrating avian neural crest cells, although its role in neural crest morphogenesis remains unclear. In vitro, tenascin-C interferes with cell-fibronectin interactions, and promotes the motility of many cell types including the neural crest. To determine if tenascin-C is a consistent component of matrices through which invasive embryonic cells migrate, we have investigated if tenascin-C is associated with 2 additional populations of motile, embryonic cells: primordial germ cells and hematopoietic progenitor cells. We have found that HNK-1, a monoclonal antibody used as a marker of neural crest, also stains avian primordial germ cells. Double-label immunohistochemistry reveals that tenascin-C is found in the mesenchyme adjacent to the ventral half of the dorsal aorta where the primordial germ cells penetrate the vessel wall, and both tenascin-C and fibronectin are present in the extracellular matrix through which the primordial germ cells migrate to reach the genital ridges. Unlike fibronectin, which is found throughout the splanchnic mesoderm, tenascin-C is concentrated in the proximal part of the splanchnic region where the primordial germ cells are concentrated. In embryos where the gonadal anlagen are surgically removed before the primordial germ cells leave the bloodstream, ectopic primordial germ cells were found exclusively in head and trunk mesenchyme containing tenascin-C. Like primordial germ cells, a subset of hematopoietic progenitor cells migrate through the mesenchyme ventral to the dorsal aorta where they form hematopoietic clusters. Others bud directly into the lumen of the aorta. Anti-tenascin-C stains the mesenchyme surrounding the migrating cells as well as the basal surfaces of the cells that appear to be budding into the lumen. In situ hybridization with a tenascin-C-specific cDNA probe shows that the major sources of the tenascin-C mRNA in this region are the hematopoietic progenitor cells themselves as well as the cells in the wall of the ventral aorta. mRNAs encoding 3 major splice variants of tenascin-C were identified by reverse transcriptase polymerase chain reaction (PCR) in the embryonic aorta and adjacent mesenchyme dissected from both the region of primordial germ cell and hematopoietic precursor cell migration. These experiments indicate that tenascin-C is a component of the migratory environment for many motile cells in the early embryo, where it has the potential to mediate cell-fibronectin interactions.