Colloidal glasses and gels: The interplay of bonding and caging

We report simulations of glassy arrest in hard-core particles with short-range interparticle attraction. Previous experiments, theory, and simulations suggest that in this kind of system, two qualitatively distinct kinds of glasses exist, dominated respectively by repulsion and attraction. It is thought that in the former, particles are trapped “topologically,” by nearest-neighbor cages, whereas in the latter, nonergodicity is due to interparticle “bonds.” Subsequent experiments and simulations have suggested that bond breaking destabilizes attractive glasses, but the long-term fate of these arrested states remains unknown. By running simulations to times a few orders of magnitude longer than those reached by previous experiments or simulations, we show that arrest in an attractive glass is, in the long run, also topological. Nevertheless, it is still possible to distinguish between “nonbonded” and “bonded” repulsive glassy states. We study the melting of bonded repulsive glasses into a hitherto unknown “dense gel” state, which is distinct from dense, ergodic fluids. We propose a “modified state diagram” for concentrated attractive particles, and discuss the relevance of our results in the light of recent rheological measurements in colloid–polymer mixtures.     

Enlargement of neuronal size in rat auditory cortex after prolonged sound exposure

Prolonged sound exposure produces functional changes in the auditory neurons. It remains unclear whether such changes are detectable with morphometric measures like cell size. Here, after exposing juvenile rats (starting on week-4) to a monotone for 7 days, we measured the size of their cortical neurons. Neuronal profiles (nuclei and perikarya) in deep layers of the primary auditory cortex were digitized and measured on photomicrographs taken from 7 μm-thick histological sections stained with toluidine blue. To facilitate digitizing cell profiles, we used an image-analysis software that contains a confocal-like image-merging function to sharpen the edges. After sound exposure, both nuclei and perikarya expanded by about 1/3 in volume compared with controls (p < 0.0001, Student's t-test). Such changes were not found in the visual cortex. Results showed that prolonged sound exposure increased the size of auditory neurons. Such activity-driven cell enlargement can be used as a simple measure to find other plastic changes in the brain.     

Intellectual, cognitive, and academic performance among sons of alcoholics, during the early school years: differences related to subtypes of familial alcoholism

BACKGROUND: Research on intellectual and cognitive functioning of children of alcoholics has been marked by inconsistency, with some studies unable to document deficits. This discrepancy may reflect the substantial heterogeneity found in the alcoholic population and among families of alcoholics. The current study sought to examine the effects of familial alcoholism subtypes on intellectual, cognitive, and academic performance in early school-aged sons of alcoholics. METHODS: Subjects for the present study were 198 elementary-age boys who were participants in the larger MSU-UM Longitudinal Study. Familial alcoholism subtypes were determined based on fathers' alcoholism and antisocial personality disorder diagnoses. Intellectual functioning was measured with the Wechsler Intelligence Scale for Children-Revised (WISC-R); academic achievement was measured with the Wide Range Achievement Test-Revised. In addition, Mazes and Freedom from Distractability factor scores of the WISC-R were used to assess abstract planning and attention abilities. RESULTS: Children of antisocial alcoholics (AALs) displayed the worst IQ and academic achievement compared with children of nonantisocial alcoholics (NAALs) and controls. In addition, children of AALs displayed relatively poorer abstract planning and attention abilities compared with children from control families. Regression analyses revealed that familial alcoholism subtype continued to account for variance in child intellectual ability even when other factors were excluded. CONCLUSIONS: Findings indicate that children from AAL families are most susceptible to relative intellectual, cognitive, and academic deficits. The study further supports the proposition that familial risk characteristics (i.e., paternal alcoholism and antisociality) may serve as effective indicators of family risk for poor intellectual outcome among offspring as early as the elementary school years.     

WNT5A exhibits tumor-suppressive activity through antagonizing the Wnt/beta-catenin signaling, and is frequently methylated in colorectal cancer.

PURPOSE: Aberrant activation of the Wnt/beta-catenin signaling pathway is associated with multiple tumors including colorectal cancer (CRC). WNT5A is a member of the nontransforming Wnt protein family, whose role in tumorigenesis is still ambiguous. We investigated its epigenetic alteration in CRCs. EXPERIMENTAL DESIGN: We examined its expression and methylation in normal colon, CRC cell lines, and tumors. We also evaluated its tumor-suppressive function and its modulation to Wnt signaling in CRC cells. RESULTS: WNT5A is silenced in most CRC cell lines due to promoter methylation, but is expressed in most normal tissues including the colon, and is unmethylated in normal colon epithelial cells. WNT5A expression could be reactivated by pharmacologic or genetic demethylation, indicating that methylation directly mediates its silencing. WNT5A methylation was frequently detected in CRC tumors (14 of 29, 48%), but only occasionally in paired normal colon tissues (2 of 15, 13%; P = 0.025). Ectopic expression of WNT5A, but not its nonfunctional short-isoform with the WNT domain deleted, in silenced CRC cells resulted in substantial inhibition of tumor cell clonogenicity, which is associated with down-regulated intracellular beta-catenin protein level and concomitant decrease in beta-catenin activity. CONCLUSIONS: WNT5A is frequently inactivated in CRC by tumor-specific methylation, and thus, is a potential biomarker. WNT5A could act as a tumor suppressor for CRC by antagonizing the Wnt/beta-catenin signaling.     

Effects of three biodiesels and a low sulfur diesel in male rats--a pilot 4-week oral study.

Because of the accessible and renewable nature of feedstock and the potential for the reduction of harmful combustion emissions and greenhouse gases, biodiesels have received increasing interest as an alternate fuel. Oral exposure to biodiesels is a concern because of contact during refuelling, accidental ingestion and exposure through ground water contamination. Although biodiesels from various feedstock are in use commercially and experimentally, very little is known about their potential adverse effects and no data is available on their potential for ground water contamination. A study was performed on male rats following oral treatment with experimental biodiesels (dissolved in corn oil) derived from canola oil (Bio-C), soy oil (Bio-S) and fish oil (Bio-F), at 500 mg/kg body weight/day, 5 days per week, for 4 weeks. Separate groups of animals were treated with low sulfur diesel (LSD) for comparison purpose, and with corn oil alone to serve as control. The potential for ground water contamination by biodiesels was investigated by the preparation of water-accommodated fractions (WAF) followed by gas chromatographic analysis. WAF from Bio-F and Bio-S was found to have the highest level of dichloromethane extractable materials. Gas chromatographic analysis indicated that the extractable materials from biodiesels contained much higher proportion of C15-C30 materials than LSD. Increased liver weight was observed in animal treated with Bio-C, Bio-S and LSD and decreased thymus weight was found in those treated with Bio-S. Histopathological changes typical of male-rat specific hyaline-droplet nephropathy were detected in kidney tubules of animals treated with LSD, Bio-S and Bio-C. Mild adaptive changes were observed in thyroids of animals treated with LSD, Bio-S and Bio-F. Clinical chemical and biochemical changes were confined to Bio-S and LSD treated rats and included elevation in some hepatic phase-I and phase-II drug metabolizing enzymes and hepatic palmitoyl Co-A oxidase, and elevated urinary concentrations of ascorbic acid and albumin. At the given dose level of 500 mg/kg bw/day, the overall treatment-related effects of biodiesels and LSD are mild, and the severity of the treatment effects may be ranked as: LSD>Bio-S>Bio-C>Bio-F. Considered together with the presence of a higher level of water extractable materials, Bio-S may be more of a concern for potential human health than Bio-C and Bio-F in an oral exposure scenario. Further studies are needed to identify and characterize the constituents contributing to the treatment-related effects specific to these experimental biodiesels.     

Single papillary muscle and ostium primum defect

Summary Parachute mitral valve (single papillary muscle) is commonly associated with complete atrioventricular (AV) canal. We report a case of ostium primum defect associated with single papillary muscle.     

Leukemia in Down Syndrome: A Review

The incidence of leukemia is higher in children with Down syndrome (DS) than in normals. In approximately 50% of cases the type of leukemia is acute megakaryoblastic leukemia (AMKL) and it occurs during the first 4 years of life. The leukemic cell also has features of erythroid progenitors and therefore appears to be a precursor cell with biphenotypic properties.     

Inferior limbal-conjunctival autograft transplantation for recurrent pterygium

PURPOSE: To study the safety and efficacy of inferior limbal-conjunctival autograft (LCAT) transplantation in the surgical management of recurrent pterygium. METHODS: Prospective non-comparative case series. Inferior limbal-conjunctival autografting was performed on 11 patients (11 eyes) with recurrent pterygium. Pterygium recurrence was considered a surgical failure. RESULTS: Recurrence of pterygium was noted in two (18.2%) eyes, after a mean follow up of 16.2 +/- 0.9 months (range: 10-19 months). Neither recurrence required further surgical treatment. Nonprogressive pseudopterygium formation was noted at the donor site in five (45.5%) eyes. CONCLUSION: Inferior LCAT appears to be a safe and effective option in the management of recurrent pterygium. In patients with suspected or proven glaucoma, this may be the procedure of choice, if mitomycin C is contraindicated.     

Intraoperative Iatrogenic Rupture of Hepatocellular Carcinoma

Intraoperative iatrogenic rupture of hepatocellular carcinoma (HCC), which can occur during hepatic resection when large tumors are being mobilized, may adversely affect the operative outcome. Little information is available in the literature on this serious intraoperative complication. The aim of the present study is to document iatrogenic rupture of HCC as a serious complication during hepatic resection and its effects on the operative and long-term outcomes of patients with this complication. A retrospective study was performed on all patients with intraoperative iatrogenic rupture of HCC during hepatic resection from 1989 to 1997, and the operative and long-term survival outcomes were compared with those of patients without the complication. Among 194 patients who underwent hepatic resection for a large HCC (> or =5 cm) during the study period, 8 (4.1%) had intraoperative iatrogenic rupture of the tumor. When compared with 186 patients with similar clinical parameters but without intraoperative rupture, patients with intraoperative rupture had significantly more intraoperative blood loss (median 5.7 vs. 2.0 L;p = 0.01) and blood transfusion requirement (median 3.1 vs 0.9 L; p = 0.02). On follow-up, patients in the intraoperative rupture group had a significantly higher intraperitoneal extrahepatic recurrence rate (33.3% vs. 2.9%; p =0.02) and significantly shorter survival (median 11.5 vs. 37.9 months,p = 0.04) when compared with patients without the complication. Intraoperative iatrogenic rupture is a serious complication of hepatic resection for HCC because it is associated with increased intraoperative blood loss, increased incidence of intraperitoneal extrahepatic recurrence, and short survival. Extreme care should be taken during mobilization of the tumor, and an alternative operative approach in the presence of a difficult hepatic resection of a large HCC may be required to avoid the complication.     

Severe acute respiratory syndrome (SARS) in Hong Kong

Severe acute respiratory syndrome (SARS) is a recently recognized and highly contagious pneumonic illness, caused by a novel coronavirus. While developments in diagnostic, clinical and other aspects of SARS research are well underway, there is still great difficulty for frontline clinicians as validated rapid diagnostic tests or effective treatment regimens are lacking. This article attempts to summarize some of the recent developments in this newly recognized condition from the Asia Pacific perspective.