Induction of a thoracolumbar supernumerary rib in rat developmental toxicity studies: A short discussion on the critical window.

Thoracolumbar supernumerary ribs (TSRs) are classified as less severe skeletal anomalies in rat developmental toxicity studies, although their incidence is relatively high in rodent studies. To investigate the characteristics of the critical window for chemically-induced TSR, in this study, rats were administered 5-fluorocytocine (5-FC) or sodium salicylate (SAL) at one of three time periods on gestational day (GD) 9, early morning (7:00 am), midday (12:00 pm to 1:00 pm), or late afternoon (4:00 pm or 7:00 pm). The incidence of TSR and other anomalies were assessed in GD20 fetuses. A single treatment with both chemicals on GD9-induced TSR, with the incidence highest when administered at 7:00 Am, decreasing gradually when administered later. This trajectory was clearer in rats treated with 5-FC than with SAL. The critical period of TSR induction is shorter in rats administered 5-FC than SAL. The characteristics of the critical window may cause variability in the incidence of TSR observed in developmental toxicity studies.

Method for Combined Observation of Serial Sections of Stented Arteries Embedded in Resin by Light Microscopy and Transmission Electron Microscopy.

We have developed a new method for obtaining information on whole tissues by light microscopy (LM) and ultrastructural features by transmission electron microscopy (TEM). This method uses serial sections of a stented artery embedded in resin. Stents were implanted in porcine coronary arteries in this study. The heart was perfusion fixed in a 2% paraformaldehyde and 1.25% glutaraldehyde mixed solution. The stented artery was then removed, fixed in 1% osmium, embedded in Quetol 651 resin, and sectioned serially. For LM, the black color of osmium was removed from the section by immersion in periodic acid and hydrogen peroxide after deplasticization. These sections were stained with hematoxylin and eosin and Elastica-Masson trichrome stain. For TEM, thin sections were re-embedded in Quetol 812 resin by the resupinate method and cut into ultrathin sections. A clear, fine structure was obtained, and organelles, microvilli, and cell junctions in the endothelium were easily observed. The combined observation of adjacent specimens by LM and TEM enabled us to relate histopathological changes in the millimeter scale to those in the nanometer scale.

Early Placebo Improvement Is a Marker for Subsequent Placebo Response in Long-Acting Injectable Antipsychotic Trials for Schizophrenia: Combined Analysis of 4 RCTs.

OBJECTIVE: Placebo effects remain largely unexplored in clinical trials of long-acting injectable (LAI) antipsychotics for schizophrenia. This study aims to characterize patients showing improvements after placebo injections and to search for criteria for the prediction of subsequent response based on the magnitude of score changes after the first week of treatment. METHODS: Data from 450 patients with schizophrenia (DSM-IV) who received placebo injections in 4 double-blind randomized controlled trials evaluating efficacy of LAI paliperidone palmitate obtained through the Yale University Open Data Access (YODA) project were analyzed. These 4 studies were conducted from October 2003 to March 2008. Multiple logistic regression analyses were conducted to examine associations between placebo response and demographic and clinical characteristics. The predictive power of improvement at week 1 for response at week 9 was investigated; sensitivity and specificity of incremental 5% cutoff points between a 5% and 25% reduction in Positive and Negative Syndrome Scale (PANSS) total score at week 1 were calculated. RESULTS: Percent reduction in the PANSS total score at week 1 and a lower PANSS G12 item score (ie, better in judgment and insight) at baseline were significantly associated with placebo response at week 9 (odds ratio [OR] = 1.063; 95% CI, 1.040-1.087, P < .001; and OR= 0.739; 95% CI, 0.553-0.986, P = .040, respectively, in the per-protocol analysis). Cutoffs of a 10% (accuracy = 0.724 in the per-protocol analysis) and 15% (accuracy = 0.722 in the last-observation-carried-forward analysis) reduction in the PANSS total score at week 1 showed the highest predictive power. CONCLUSIONS: The appreciation that longer-term response following placebo injections can be predicted by a 10%-15% PANSS total score reduction at week 1 could guide the design of future clinical trials of LAI antipsychotics in schizophrenia to identify and exclude potential placebo responders early during the course of the study.

Acute changes in histopathology and intravascular imaging after catheter-based renal denervation in a porcine model.

OBJECTIVES: We first aimed to identify the histopathological changes occurring immediately after renal denervation (RDN) with radiofrequency energy, and then to assess the feasibility of determining procedural success using currently available clinical intravascular imaging techniques. BACKGROUND: Catheter-based RDN has been used as an alternative therapy for hypertension. However, no practical endpoint to determine procedural success during treatment has been established. METHODS: A total of 39 ablation lesions were induced in vivo in eight porcine renal arteries and a total of 15 ablation lesions were induced ex vivo in five excised porcine renal arteries with a radiofrequency delivery device. Acute histological changes and appearance on intravascular imaging of the lesions were investigated with light microscopy, transmission electron microscopy, intravascular ultrasound (IVUS), and optical frequency domain imaging (OFDI). RESULTS: Marked changes were noted in media, adventitia, and perirenal-arterial nerves immediately after in vivo ablation. Changes visualized on IVUS were characterized by focal adventitial thickening comprising a relatively echogenic layer around a heterogeneously hypoechoic interior region, and on OFDI as disappearance of the external elastic membrane signals with high scattering of signals in the surface layer. The changes after ex vivo ablation were histopathologically identical to those from in vivo ablation. There were statistically significant positive correlations in measured dimensions (area, depth, width, and diameter) of ablation lesions between histopathology and IVUS/OFDI findings (Pearson correlation coefficients = 0.69-0.77). CONCLUSIONS: These findings suggest that observation of treated renal arteries by IVUS or OFDI immediately after RDN improves the success rate of RDN.

Stress-reactive rats (high-avoidance female rats) have a shorter lifespan than stress-nonreactive rats (low-avoidance female rats).

Although Hatano high-avoidance and low-avoidance rats (HAA and LAA, respectively) have been selectively bred for good versus poor avoidance learning, HAA rats are known to be more reactive to stress than LAA rats. In this study, HAA and LAA female rats were compared during reproductive aging by observing estrous cycles from 8 to 11 months of age. Furthermore, these rats were allowed to live out their natural lifespans, that is, until 24 months of age, in order to compare their survival and to clarify the relationship between reproductive aging and tumor development. At eight months of age, 2 of 35 HAA rats and 20 of 35 LAA rats had abnormal estrous cycles. The median lifespan of the HAA rats (673 days) was shorter than that of the LAA rats (733 days). The incidence of pituitary neoplasia was higher in the HAA rats than in the LAA rats. These results suggest that HAA female rats (i.e., stress-reactive rats) have a shorter lifespan than LAA female rats (i.e., stress-nonreactive rats) and develop pituitary neoplasia, which was one of the causal factors in their accelerated mortality. However, the onset of an age-matched abnormal cycle did not correspond with their lifespan.

In vivo comet assay of acrylonitrile, 9-aminoacridine hydrochloride monohydrate and ethanol in rats.

As part of the Japanese Center for the Validation of Alternative Methods (JaCVAM)-initiative international validation study of the in vivo rat alkaline comet assay, we examined the ability of acrylonitrile, 9-aminoacridine hydrochloride monohydrate (9-AA), and ethanol to induce DNA damage in the liver and glandular stomach of male rats. Acrylonitrile is a genotoxic carcinogen, 9-AA is a genotoxic non-carcinogen, and ethanol is a non-genotoxic carcinogen. Positive results were obtained in the liver cells of male rats treated with known genotoxic compounds, acrylonitrile and 9-AA.