Reconnaissance of tumor immune microenvironment spatial heterogeneity in metastatic renal cell carcinoma and correlation with immunotherapy response.

A clearer understanding of the tumor immune microenvironment (TIME) in metastatic clear cell renal cell carcinoma (ccRCC) may help to inform precision treatment strategies. We sought to identify clinically meaningful TIME signatures in ccRCC. We studied tumors from 39 patients with metastatic ccRCC using quantitative multiplexed immunofluorescence and relevant immune marker panels. Cell densities were analyzed in three regions of interest (ROIs): tumor core, tumor-stroma interface and stroma. Patients were stratified into low- and high-marker density groups using median values as thresholds. Log-rank and Cox regression analyses while controlling for clinical variables were used to compare survival outcomes to patterns of immune cell distributions. There were significant associations with increased macrophage (CD68+ CD163+ CD206+ ) density and poor outcomes across multiple ROIs in primary and metastatic tumors. In primary tumors, T-bet+ T helper type 1 (Th1) cell density was highest at the tumor-stromal interface (P = 0·0021), and increased co-expression of CD3 and T-bet was associated with improved overall survival (P = 0·015) and survival after immunotherapy (P = 0·014). In metastatic tumor samples, decreased forkhead box protein 3 (FoxP3)+ T regulatory cell density correlated with improved survival after immunotherapy (P = 0·016). Increased macrophage markers and decreased Th1 T cell markers within the TIME correlated with poor overall survival and treatment outcomes. Immune markers such as FoxP3 showed consistent levels across the TIME, whereas others, such as T-bet, demonstrated significant variance across the distinct ROIs. These findings suggest that TIME profiling outside the tumor core may identify clinically relevant associations for patients with metastatic ccRCC.

General and specific combining abilities in a maize (Zea mays L.) test-cross hybrid panel: relative importance of population structure and genetic divergence between parents.

KEY MESSAGE: General and specific combining abilities of maize hybrids between 288 inbred lines and three tester lines were highly related to population structure and genetic distance inferred from SNP data. Many studies have attempted to provide reliable and quick methods to identify promising parental lines and combinations in hybrid breeding programs. Since the 1950s, maize germplasm has been organized into heterotic groups to facilitate the exploitation of heterosis. Molecular markers have proven efficient tools to address the organization of genetic diversity and the relationship between lines or populations. The aim of the present work was to investigate to what extent marker-based evaluations of population structure and genetic distance may account for general (GCA) and specific (SCA) combining ability components in a population composed of 800 inter and intra-heterotic group hybrids obtained by crossing 288 inbred lines and three testers. Our results illustrate a strong effect of groups identified by population structure analysis on both GCA and SCA components. Including genetic distance between parental lines of hybrids in the model leads to a significant decrease of SCA variance component and an increase in GCA variance component for all the traits. The latter suggests that this approach can be efficient to better estimate the potential combining ability of inbred lines when crossed with unrelated lines, and limits the consequences of tester choice. Significant residual GCA and SCA variance components of models taking into account structure and/or genetic distance highlight the variation available for breeding programs within structure groups.

Association mapping for phenology and plant architecture in maize shows higher power for developmental traits compared with growth influenced traits.

Plant architecture, phenology and yield components of cultivated plants have repeatedly been shaped by selection to meet human needs and adaptation to different environments. Here we assessed the genetic architecture of 24 correlated maize traits that interact during plant cycle. Overall, 336 lines were phenotyped in a network of 9 trials and genotyped with 50K single-nucleotide polymorphisms. Phenology was the main factor of differentiation between genetic groups. Then yield components distinguished dents from lower yielding genetic groups. However, most of trait variation occurred within group and we observed similar overall and within group correlations, suggesting a major effect of pleiotropy and/or linkage. We found 34 quantitative trait loci (QTLs) for individual traits and six for trait combinations corresponding to PCA coordinates. Among them, only five were pleiotropic. We found a cluster of QTLs in a 5 Mb region around Tb1 associated with tiller number, ear row number and the first PCA axis, the latter being positively correlated to flowering time and negatively correlated to yield. Kn1 and ZmNIP1 were candidate genes for tillering, ZCN8 for leaf number and Rubisco Activase 1 for kernel weight. Experimental repeatabilities, numbers of QTLs and proportion of explained variation were higher for traits related to plant development such as tillering, leaf number and flowering time, than for traits affected by growth such as yield components. This suggests a simpler genetic determinism with larger individual QTL effects for the first category.

Dent and Flint maize diversity panels reveal important genetic potential for increasing biomass production.

KEY MESSAGE: Genetic and phenotypic analysis of two complementary maize panels revealed an important variation for biomass yield. Flowering and biomass QTL were discovered by association mapping in both panels. The high whole plant biomass productivity of maize makes it a potential source of energy in animal feeding and biofuel production. The variability and the genetic determinism of traits related to biomass are poorly known. We analyzed two highly diverse panels of Dent and Flint lines representing complementary heterotic groups for Northern Europe. They were genotyped with the 50 k SNP-array and phenotyped as hybrids (crossed to a tester of the complementary pool) in a western European field trial network for traits related to flowering time, plant height, and biomass. The molecular information revealed to be a powerful tool for discovering different levels of structure and relatedness in both panels. This study revealed important variation and potential genetic progress for biomass production, even at constant precocity. Association mapping was run by combining genotypes and phenotypes in a mixed model with a random polygenic effect. This permitted the detection of significant associations, confirming height and flowering time quantitative trait loci (QTL) found in literature. Biomass yield QTL were detected in both panels but were unstable across the environments. Alternative kinship estimator only based on markers unlinked to the tested SNP increased the number of significant associations by around 40% with a satisfying control of the false positive rate. This study gave insights into the variability and the genetic architectures of biomass-related traits in Flint and Dent lines and suggests important potential of these two pools for breeding high biomass yielding hybrid varieties.

Permanent pacemaker insertion after CoreValve transcatheter aortic valve implantation: incidence and contributing factors (the UK CoreValve Collaborative).

BACKGROUND: Permanent pacemaker (PPM) requirement is a recognized complication of transcatheter aortic valve implantation. We assessed the UK incidence of permanent pacing within 30 days of CoreValve implantation and formulated an anatomic and electrophysiological model. METHODS AND RESULTS: Data from 270 patients at 10 centers in the United Kingdom were examined. Twenty-five patients (8%) had preexisting PPMs; 2 patients had incomplete data. The remaining 243 were 81.3±6.7 years of age; 50.6% were male. QRS duration increased from 105±23 to 135±29 milliseconds (P<0.01). Left bundle-branch block incidence was 13% at baseline and 61% after the procedure (P<0.001). Eighty-one patients (33.3%) required a PPM within 30 days. Rates of pacing according to preexisting ECG abnormalities were as follows: right bundle-branch block, 65.2%; left bundle-branch block, 43.75%; normal QRS, 27.6%. Among patients who required PPM implantation, the median time to insertion was 4.0 days (interquartile range, 2.0 to 7.75 days). Multivariable analysis revealed that periprocedural atrioventricular block (odds ratio, 6.29; 95% confidence interval, 3.55 to 11.15), balloon predilatation (odds ratio, 2.68; 95% confidence interval, 2.00 to 3.47), use of the larger (29 mm) CoreValve prosthesis (odds ratio, 2.50; 95% confidence interval, 1.22 to 5.11), interventricular septum diameter (odds ratio, 1.18; 95% confidence interval, 1.10 to 3.06), and prolonged QRS duration (odds ratio, 3.45; 95% confidence interval, 1.61 to 7.40) were independently associated with the need for PPM. CONCLUSION: One third of patients undergoing a CoreValve transcatheter aortic valve implantation procedure require a PPM within 30 days. Periprocedural atrioventricular block, balloon predilatation, use of the larger CoreValve prosthesis, increased interventricular septum diameter and prolonged QRS duration were associated with the need for PPM.

Prevalence of antibodies against Kilham virus in experimental rat colonies of Argentina.

The Kilham rat virus (KRV) is a parvovirus originally isolated from a rat sarcoma in the late 1950s. The clinical signs associated with a natural KRV infection include foetal resorption in dams, runting, ataxia, cerebellar hypoplasia and jaundice in suckling rats, and sudden death, scrotal cyanosis, abdominal swelling and dehydration in juvenile rats. The ability of this virus to produce persistent infections has resulted in a high frequency of contamination of cell cultures and transplantable-tumor system. In addition, the virus may interfere with research in other ways. The remarkable resistance to environmental conditions determines the importance of the detection and control of this agent, especially in the laboratory animal production. This study determines the seroprevalence of Kilham antibodies from sera of adult rats from conventional facilities, using the haemagglutination inhibition test. The seroprevalence varied between 27.8% and 75%. This result confirms that the virus is circulating in Argentinean conventional facilities and might be interfering with research. The recognized Kilham virus may be prevented from supply sources by implementing a health monitoring schedule including a regular serological surveillance, and by keeping the animals under barrier systems.

Expression of a truncated, kinase-defective TGF-beta type II receptor in mouse skeletal tissue promotes terminal chondrocyte differentiation and osteoarthritis.

Members of the TGF-beta superfamily are important regulators of skeletal development. TGF-betas signal through heteromeric type I and type II receptor serine/threonine kinases. When over-expressed, a cytoplasmically truncated type II receptor can compete with the endogenous receptors for complex formation, thereby acting as a dominant-negative mutant (DNIIR). To determine the role of TGF-betas in the development and maintenance of the skeleton, we have generated transgenic mice (MT-DNIIR-4 and -27) that express the DNIIR in skeletal tissue. DNIIR mRNA expression was localized to the periosteum/perichondrium, syno-vium, and articular cartilage. Lower levels of DNIIR mRNA were detected in growth plate cartilage. Transgenic mice frequently showed bifurcation of the xiphoid process and sternum. They also developed progressive skeletal degeneration, resulting by 4 to 8 mo of age in kyphoscoliosis and stiff and torqued joints. The histology of affected joints strongly resembled human osteo-arthritis. The articular surface was replaced by bone or hypertrophic cartilage as judged by the expression of type X collagen, a marker of hypertrophic cartilage normally absent from articular cartilage. The synovium was hyperplastic, and cartilaginous metaplasia was observed in the joint space. We then tested the hypothesis that TGF-beta is required for normal differentiation of cartilage in vivo. By 4 and 8 wk of age, the level of type X collagen was increased in growth plate cartilage of transgenic mice relative to wild-type controls. Less proteoglycan staining was detected in the growth plate and articular cartilage matrix of transgenic mice. Mice that express DNIIR in skeletal tissue also demonstrated increased Indian hedgehog (IHH) expression. IHH is a secreted protein that is expressed in chondrocytes that are committed to becoming hypertrophic. It is thought to be involved in a feedback loop that signals through the periosteum/ perichondrium to inhibit cartilage differentiation. The data suggest that TGF-beta may be critical for multifaceted maintenance of synovial joints. Loss of responsiveness to TGF-beta promotes chondrocyte terminal differentiation and results in development of degenerative joint disease resembling osteoarthritis in humans.

[Drepanocytosis with alpha and beta(o) thalassemia: a case report]. / Drépanocytose beta(o) thalassémique associée à une alpha thalassémie: à propos d'un cas.

We describe the case of a Sickle Cell Trait associated with alpha and beta(o) thalassemia at an young man without clinical abnormality. Capillary electrophoresis showed S haemoglobin at 67%, F haemoglobin at 29%, A2 haemoglobin at 4% and an absence of A haemoglobin. Accurate diagnosis was found by techniques of molecular biology.

[Results of the French register of renal stenting: the Esternal study]. / Résultats du registre français du stenting rénal: étude Esternal.

Renal artery angioplasty using the same techniques employed for coronary arteries has developed considerably. A register was set up in France to evaluate the efficacy of this treatment for improving renal function and lowering blood pressure in cardiac patients. Between 2001 and 2005, 205 patients (234 lesions) were treated in 14 centres (mean age: 69.2 +/- 10.4 years, 59% male). All of the patients had hypertension and the majority of them (171) had renal failure (creatinine clearance<90 ml/min). Direct implantation of a stent was performed in 75.2% of the cases, successfully in 196 patients (96%) with 220 lesions (95.2%). The complications encountered were segmental renal infarction in two patients (0.9%), and four cases of minor vascular complications at the puncture site (2%). The mean value for pre-implantation creatinine clearance was 54.6 +/- 32.8 ml/min and 58.1 +/- 36.0 post- implantations. The duration of follow up was 5.9 +/- 2.7 months. Mortality was 3.5% (seven patients, of whom two died from renal causes). The mean systolic and diastolic blood pressure was 142.2 +/- 16.2 and 78.9 +/- 9.5 respectively versus 164.9 +/- 25.2 and 89.1 +/- 14.8 before treatment (p<0.0001). A non-significant improvement in creatinine clearance at six months was also observed in patients with renal failure prior to treatment: 48.7 +/- 17.1 ml/min vs. 69.2 +/- 160.3. Renal artery stenting in cardiac patients with renal artery stenosis is associated with a very high success rate, with few complications and an improvement in hypertension and renal function.

Neuropathic toe ulcers treated with toe flexor tenotomies.

BACKGROUND: Foot ulcers are common causes of hospital admissions for infection and amputation in patients with neuropathy. This retrospective study evaluates the results of treating plantar neuropathic toe ulcers with percutaneous flexor tenotomy. METHODS: From 1996 to 2003, 28 toe ulcers in 18 patients were treated with tenotomy of the toe flexors. RESULTS: Fourteen of 18 patients had diabetic neuropathy. No patients were lost to followup. Average followup for the 28 ulcers was 36 (range 20 to 65) months. All ulcers healed. None of the 11 lesser toe ulcers recurred. Three of 17 first toe ulcers recurred but two that had repeat tenotomy healed and did not recur. There were no toe amputations, infections, or other complications of tenotomy. One patient had unrelated transtibial amputation. CONCLUSIONS: No long-term results of treating toe ulcers with toe flexor tenotomy by other authors have been found. Toe flexor tenotomies appear to be effective and safe treatment for neuropathic toe ulcers.

An original fibular shortening osteotomy technique in tibiotalar arthrodesis.

Tibiotalar arthrodesis (TTA) is the gold-standard treatment for advanced ankle osteoarthritis. We describe an original fibular shortening osteotomy (FSO) performed during TTA, to allow complete talar ascension and reduce the nonunion rate. Forty-two FSOs were associated to TTA (19 fixed by cross-screwing and 23 by anatomic plates) and assessed clinically and radiographically. At 24.7 months' follow-up, fusion rates were 97.6% for TTA and 100% for FSO, with mean fusion time of 5.2 months. One infection and 1 nonunion (4.7%) required further surgery, with complete resolution. Radiological and clinical outcome in TTA, lack of specific complications of FSO and ease of implementation encourage us to publish the technique.

Preliminary Results of Primary Gastrocnemius-Soleus Recession for Midfoot Charcot Arthropathy.

UNLABELLED: Background Treatment of Charcot arthopathy of the foot can be challenging. The goal of this investigation was to determine whether primary gastrocnemius-soleus recession could decrease rate of new ulcers, progression of deformity, and amputation in patients with Charcot arthropathy of the midfoot.Methods A retrospective chart review revealed 28 feet in 24 diabetic patients with radiographic evidence of Charcot arthropathy of the midfoot. They were treated with primary gastrocnemius-soleus recession. Eleven feet in 11 patients had concurrent plantar midfoot ulcers. Three feet in 3 patients were lost to follow-up. Twenty-five feet in 21 patients were followed for an average of 37 months postoperatively (range = 18-79).Results A favorable outcome was defined as healing of existing ulcers, no new ulcers, no obvious progression of deformity, and no amputation. Favorable outcomes were obtained in 22 of 25 feet (18 of 21 patients). Only one patient had a persistent ulcer after gastrocnemius-soleus recession. The other 10 patients with preexisting ulcers healed. Deformity of midfoot progressed in one patient, leading ultimately to transtibial amputation. Another patient developed a knee joint infection and had a transfemoral amputation at another institution.Discussion These preliminary data suggest that primary gastrocnemius-soleus recession is followed by a much lower rate of persistent, recurrent, and new ulceration than previously reported studies. Gastrocnemius-soleus recession seems to aid in the treatment of Charcot arthropathy of the midfoot. LEVELS OF EVIDENCE: Level IV.

In-stent restenosis: long-term outcome and predictors of subsequent target lesion revascularization after repeat balloon angioplasty.

OBJECTIVES: We sought to evaluate the long-term clinical outcome of patients undergoing successful balloon angioplasty for in-stent restenosis, and to determine correlates of the need for subsequent target lesion revascularization (TLR). BACKGROUND: In-stent restenosis can be safely treated by repeat percutaneous intervention. Reported subsequent TLR rates have varied from 20% to 80% and seem related to the type of restenotic lesion. METHODS: The study population comprised 234 patients with follow-up data who were successfully treated with repeat balloon angioplasty for in-stent restenosis in 257 lesions between May 1995 and January 1998 at our institution. RESULTS: Clinical follow-up was available at 459 (286 to 693) days after the repeat procedure. Event-free survival was 78.5% and 74.6% at 12 and 24 months, respectively. Recurrent events occurred in 58 patients (24.8%), including 6 deaths (2.6%), 4 myocardial infarction (1.7%) and repeat target vessel revascularization in 50 patients (21.4%). Independent predictors of repeat TLR were time to in-stent restenosis <90 days (Hazard ratio 4.67, p < 0.001), minimal luminal diameter after repeat procedure (Hazard ratio 0.38, p = 0.034) and the angiographic pattern of in-stent restenosis (Hazard ratio 1.65, p = 0.036). CONCLUSIONS: Balloon angioplasty is an effective means of treating in-stent restenosis. The long-term results are acceptable particularly for focal restenotic lesions. Further restenosis is more common in patients with early initial recurrence, more proliferative lesions and a poorer angiographic result from repeat angioplasty.

Results of stenting of unprotected left main coronary artery stenosis in patients at high surgical risk.

From March 1994 to September 1996, 39 patients underwent stenting of the unprotected left main coronary artery because of high surgical risk. Stenting appeared to improve clinical outcome, but there was a significant mortality rate at long-term follow-up.

Pharmacokinetic considerations of dexamethasone-induced developmental toxicity in rats.

Dexamethasone (DEX) has been shown to elicit growth stunting and cleft palate in rat fetuses. This investigation characterized DEX dosimetry as various pharmacokinetic parameters and evaluated their impact on developmental toxicity endpoints. DEX pharmacokinetics was evaluated as a single dose on either gestation day (GD) 9 or 14, as well as on GD 14 after multiple daily dosing from GD 9 to GD 14. An additional set of pregnant rats was dosed with DEX on GD 9 through GD 14, pharmacokinetic evaluation was conducted on GD 14 through GD 16, and teratological evaluation was conducted following sacrifice on GD 20. For all pharmacokinetic evaluations, a subcutaneous (sc) injection of 0.8 mg DEX/kg body weight together with 50 microCi 3H-DEX was administered to Sprague-Dawley rats. Blood, urine, and feces were collected for 24 or 48 h. At GD 20 sacrifice, maternal tissues as well as fetal brain and liver samples were collected as part of the laparotomy. All samples were assayed using scintillation spectrometry. DEX pharmacokinetic parameters remained similar whether dosing occurred early (GD 9) or late (GD 14) in organogenesis, or dosing occurred on multiple sequential days (GD 9-14). DEX produced maternal and fetal weight loss, fetal lethality, and cleft palate. DEX a-half-life was positively correlated with the percentage of implants affected [(number of non-live + number with cleft palate)/number of implants]/litter. Neither the area under the concentration-time curve (AUC), the maximum maternal plasma concentration (Cmax), nor the terminal phase beta-half-life correlated with any fetal outcome parameters. The correlation between the percentage of the litter that was affected and half-life was improved if AUC was added in a stepwise multiple regression. These data suggest that the length of time that DEX is present in the maternal plasma at a sufficiently high concentration (i.e., slower tissue distribution of DEX) appears to be important in determining the risk of an adverse outcome in the offspring.

Retinoic acid-induced stress protein synthesis in the mouse.

We have previously demonstrated that stress proteins (SPs) are synthesized in tissues in which malformations are later observed following treatment with the developmental toxicant, retinoic acid (RA), on day 11 of gestation (GD 11). These proteins were not synthesized in tissues which did not present with malformations near partuition. The purpose of the present investigation was to determine if this correlation between early SP synthesis and later malformation was present at other times during gestation. CD-1 strain mice were dosed orally with corn oil or 100 mg/kg body weight RA on GD 10 or 13. Some of the mice in each group were given an intraperitoneal injection of 3H-leucine to label embryonic protein synthesis one hour after dosing with RA. These animals were sacrificed 1.5 hour later, and embryonic protein synthesis was determined by two-dimensional gel electrophoresis followed by autoradiography. Other animals in each group were sacrificed on day 17 of gestation, and fetuses were examined for the presence of malformations. Following treatment with RA on day 10 of gestation, malformations were observed in the forelimbs, the hindlimbs and the tail; heart defects were not observed. SPs of 20-25,000 and 90,000 relative molecular mass (Mr) were synthesized in the forelimb bud and tail; in addition, a second low molecular weight (20-25,000) and a 84,000 Mr SPs were synthesized in forelimb buds. No SPs were synthesized in the hindlimb bud or the heart. Following RA treatment on GD 13, cleft palate was observed in 58% of fetuses; no other malformations were found. Proteins of 34,000, 84,000 and 90,000 Mr were synthesized in craniofacial tissue; SPs were not observed in forelimb bud, hindlimb bud, heart or tail tissues at this time. Therefore, it appears that there may be a correlation between tissue-specific SP synthesis early in organogenesis and the presence of a malformation later in gestation.

Climate, diffused solar radiation and multiple sclerosis.

Environmental factors implicated as affecting world-wide distribution of multiple sclerosis are reviewed. It is suggested that climate may be involved in the etiology of this disease. Diffused solar radiation effects on multiple sclerosis hospital admission rates are demonstrated.

Influence of weather on osteoarthritics.

This exploratory study examined the effects of selected weather variables on pain and pain-related stress in osteoarthritic subjects. Urban and rural dwelling arthritics who perceived that weather made their symptoms worse and those who did not were surveyed. Some persons with osteoarthritis in urban Chicago were more weather sensitive than their rural counterparts in Grand Forks, North Dakota. Multiple regression analysis showed that precipitation affected degree of pain for urban subjects who identified weather as a pain-generating factor; barometric pressure, relative humidity and sunshine were significant factors influencing pain-related stress. Wind speed correlated with pain and pain-related stress; relative humidity and precipitation correlated with pain-related stress for urban subjects who did not perceive weather as a problem. Specific weather variables were not identified as affecting rural subjects' pain. However, temperature and barometric pressure affected degree of pain-related stress in rural subjects who perceived weather as a problem. Subtle differences between Chicago urban and Grand Forks rural climates are reflected in arthritic subjects' degree of pain and their perception of pain-related stress.

Retinoic acid acts during peri-implantational development to alter axial and brain formation.

All-trans retinoid acid (RA) induces a stereotypic spectrum of stage-specific malformations in vertebrate conceptuses. The present work evaluated the anatomic and biochemical effects of exposure to RA in mouse embryos at a peri-implantational stage of development - gestational day (GD) 5. The RA receptors (RARs) beta and gamma, the retinoid X receptors (RXRs) alpha and beta, and the cellular retinoid acid binding proteins (CRABPs) I and II were detected by RT-PCR in both control and treated individual GD 5 decidua/embryo complexes 3 h after RA injection, indicating the presence of the mRNAs coding for the proteins that mediate the effects of RA. In contrast, the RAR alpha mRNA was detected in some but not all decidua/embryo complexes, both control and treated, suggesting that its expression is initiated at approximately GD 5, while RXR gamma mRNA was not detected. Examination of the control and RA-exposed embryos on GD 10, 12, or 17 showed that greater than 50% of the RA-exposed embryos were adversely affected, many with defects found only after serial histopathological examination. The malformations were localized primarily in the central nervous system, the branchial arches, and their derivatives. These terata included excessive folding and elevation of the neural tube floor plate, exencephaly (with detachment of the cephalic neuroepithelium and rarefied cephalic mesenchyme), persistent patency of Rathke's pouch, small trigeminal ganglia, neural diverticula (chiefly from the spinal cord), and/or various optic and otic defects. Unexpectedly, limb reduplications were not apparent in RA-exposed fetuses. Those litters examined on GD 17 had a high percentage of resorbed or malformed implantations, and the few apparently normal fetuses were developmentally delayed with respect to bone ossification. These data confirm that the development of neural- and neural crest-derived structures are severely disrupted by RA exposure prior to initial specification of the neural plate and suggest that many of the proteins that regulate RA signaling are available in early vertebrate embryos at this developmental stage.

Dose-response of retinoic acid induced stress protein synthesis and teratogenesis in mice.

Stress proteins are synthesized in response to a variety of stressors, including several teratogenic agents. However, their role, if any, in the teratogenic process is unknown. We have previously demonstrated that all-trans-retinoic acid administered to pregnant CD-1 mice on gestational day 11 or 13 produced limb defects and cleft palate near term in a dose-responsive manner. This chemical also induced the synthesis of several nuclear stress proteins in embryonic tissues within several hours of dosing. The stress proteins were only observed in tissues that eventually became malformed and not in tissues that appeared normal at term. In the current work, we examined the stress response in embryonic target tissues after several different doses of retinoic acid. The nuclear stress proteins were synthesized in a dose-related manner and at a lower retinoic acid dose than doses producing malformations in the corresponding tissue at birth. Each individual stress protein and the total stress protein response were highly correlated, across dose, with the respective malformations observed at term.