Activation of the Notch pathway in the hair cortex leads to aberrant differentiation of the adjacent hair-shaft layers

Little is known about the mechanisms underlying the generation of various cell types in the hair follicle. To investigate the role of the Notch pathway in this process, transgenic mice were generated in which an active form of Notch1 (Notch(DeltaE)) was overexpressed under the control of the mouse hair keratin A1 (MHKA1) promoter. MHKA-Notch(DeltaE) is expressed only in one precursor cell type of the hair follicle, the cortex. Transgenic mice could be easily identified by the phenotypes of curly whiskers and wavy, sheen pelage hair. No effects of activated Notch on proliferation were detected in hair follicles of the transgenic mice. We find that activating Notch signaling in the cortex caused abnormal differentiation of the medulla and the cuticle, two neighboring cell types that did not express activated Notch. We demonstrate that these non-autonomous effects are likely caused by cell-cell interactions between keratinocytes within the hair follicle and that Notch may function in such interactions either by directing the differentiation of follicular cells or assisting cells in interpreting a gradient emanating from the dermal papilla.

Modulation of sperm tail protein tyrosine phosphorylation by pentoxifylline and its correlation with hyperactivated motility

OBJECTIVE

To assess the effect of pentoxifylline on human sperm functions that are crucial to fertilization.

DESIGN

Prospective, controlled study.

SETTING

Academic tertiary care institute.

PATIENT(S)

Healthy male sperm donors.

INTERVENTION(S)

The effects of pentoxifylline (3.6 mM) on hyperactivated motility, sperm binding to the zona pellucida, and sperm protein tyrosine phosphorylation were evaluated.

MAIN OUTCOME MEASURE(S)

Hyperactivated motility was assessed by computer-assisted motion analysis, and tight binding of sperm to homologous zonae pellucidae was examined using the hemizona assay. Sperm protein phosphorylation was evaluated using indirect immunofluorescence with an antibody to phosphotyrosine (PY20).

RESULT(S)

Pentoxifylline significantly stimulated hyperactivated motility at 1 hour and 4 hours; it also significantly increased sperm binding to the zona pellucida and enhanced sperm tail tyrosine phosphorylation at 4 hours under capacitating conditions. There was a statistically significant correlation between hyperactivated motility and sperm tail protein phosphorylation.

CONCLUSION(S)

Pentoxifylline stimulates sperm functions that are essential to achieving fertilization under in vitro conditions in sperm obtained from fertile men. The enhancement of hyperactivated motility is associated with the stimulation of sperm tail tyrosine phosphorylation, suggesting a causal relation and the involvement of a modulatory effect after cyclic adenosine monophosphate-dependent phosphorylation of intermediate proteins.

Pentoxifylline stimulates various sperm motion parameters and cervical mucus penetrability in patients with asthenozoospermia

Pentoxifylline (PTX) was incubated in vitro with human spermatozoa to examine its effects on sperm motility characteristics and bovine cervical mucus penetrability (BCMP). Sperm motion parameters were assessed by computer-assisted motion analysis (CASA) using HTM-IVOS and BCMP was evaluated using the Penetrak kit. In vitro incubation with PTX (1 mg ml-1; 3.6 mM, 30 min) did not significantly change percentage motility, average path velocity (VAP), straight-line velocity (VSL) or beat cross frequency (BCF) of spermatozoa from normozoospermic or asthenozoospermic samples. However, it significantly increased curvilinear velocity (VCL), amplitude of lateral head displacement (ALH) and hyperactivated motility (HA), and significantly decreased linearity (LIN) of spermatozoa from both samples. Pentoxifylline was found to increase BCMP scores for spermatozoa from asthenozoospermic samples, but did not affect scores for spermatozoa from normozoospermic samples. Bovine cervical mucus penetrability (BCMP) was found to be positively and significantly correlated with the percentage motility of both non-PTX-treated and PTX-treated spermatozoa for asthenozoospermic samples. These results demonstrated that PTX enhanced several motion sperm parameters as well as BCMP in asthenozoospermic samples and suggest a potential use of the methylxanthine in infertile patients with motility defects undergoing artificial insemination.

Transactivation of the human MDR1 gene by hepatitis B virus X gene product

BACKGROUND/AIMS

Persistent hepatitis B virus (HBV) infection may cause hepatocellular carcinoma. Patients with hepatocellular carcinoma are characterized by nonresponsiveness to chemotherapeutic agents. While many studies have been devoted to understanding the hepatocarcinogenesis mechanism of HBV, the possible relationship between HBV and the drug sensitivity phenotype of cancer cells has rarely been addressed. The hepatitis B virus X gene encodes a transcription transactivator which has been suggested to be a potential factor in viral hepatocarcinogenesis. The role of HBV pX in mediating the drug resistance phenotype of hepatoma cell lines was examined in this study.

METHODS

Standard transfection and chloramphenicol acetyltransferase assay were utilized to examine the effect of HBV pX transactivator on a reporter gene under the control of the human multidrug resistance (MDR) 1 upstream regulatory elements. Selected Hep G2 clones with or without HBV pX expression were tested for their sensitivity towards various anti-cancer agents by utilization of MTT assay.

RESULTS

The expression of HBV pX in both Hep G2 (p53+) and Hep 3B (p53-) cells resulted in transactivation of the reporter gene under control of the human MDR1 upstream regulatory elements. Northern blot analysis indicated that expression of the endogenous MDR1 gene was also elevated in Hep G2 clones with HBV pX expression. Decreased drug sensitivity towards adriamycin, vinblastine, and VP-16 was observed in Hep G2 clones with HBV pX expression.

CONCLUSIONS

HBV pX can transactivate the MDR1 gene. Drug sensitivity was altered in Hep G2 cells with HBV pX expression.

Plasma membrane integrity of cryopreserved human sperm: an investigation of the results of the hypoosmotic swelling test, the water test, and eosin-Y staining

OBJECTIVE

[1] To examine the relationship between sperm membrane integrity and motion parameters before and after cryopreservation; [2] to determine the capacity of the membrane integrity tests to predict the outcome of cryopreservation in fertile and infertile men; and [3] to examine the degree of agreement between tail and head membrane integrity of testicular and ejaculated immotile sperm cryopreserved for intracytoplasmic sperm injection.

DESIGN

Prospective study.

SETTING

Academic tertiary care institution.

PATIENT(S)

Fertile donors and normozoospermic oligozoospermic, and asthenozoospermic subfertile men.

INTERVENTION(S)

Semen samples were cryopreserved and thawed for analysis.

MAIN OUTCOME MEASURE(S)

Sperm membrane integrity and computer-assisted motion parameters.

RESULT(S)

The hypoosmotic swelling test and water test had a significant and positive correlation in the fresh and cryopreserved ejaculates of all groups. The results of the hypoosmotic swelling test correlated positively with the percent motility in the fresh ejaculates of fertile and subfertile men. None of the membrane integrity tests correlated with the cryosurvival rate in any group. In the ejaculated and testicular samples with no postcryopreservation motility, the simultaneous assessment of hypoosmotic swelling test and eosin showed that of 33% sperm exhibiting coiling with the hypoosmotic swelling test, only 9% were eosin negative, whereas 24% were eosin positive.

CONCLUSION(S)

[1] The water test may be a simpler replacement for the hypoosmotic swelling test; [2] none of the membrane integrity tests predicted sperm motility after cryopreservation; and [3] there was a high degree of disagreement between the hypoosmotic swelling test and eosin in the samples with no postcryopreservation motility.

Separating X-bearing human spermatozoa through a discontinuous Percoll density gradient proved to be inefficient by double-label fluorescent in situ hybridization

PURPOSE

Double-label fluorescence in situ hybridization (FISH) was used to evaluate the efficiency of separating X- and Y-chromosome-bearing spermatozoa through 12-step discontinuous Percoll gradients.

METHODS

Liquefied normal semen samples from 10 healthy donors were overlaid onto 25% Percoll and centrifuged. Parts of the sperm pellet were saved as control, while the remaining portion was separated by 12-step Percoll gradient. After centrifugation, the spermatozoa in the 80% Percoll layer were collected. The X:Y ratio of the control and separated spermatozoa was verified by double-label FISH (CEP SOX/SGY probes) and scored blindly by one observer. Differences in the X:Y ratios between matched groups were analyzed by paired t tests.

RESULTS

The overall average labeling efficiency was 99.2%. A significant enrichment (P = 0.02) of X-bearing spermatozoa was obtained in Percoll separated fractions (mean X:Y ratio = 52.2:46.4) compared with the control group (X:Y ratio = 49.5:48.4). Discontinuous Percoll gradients also decreased the proportion of aneuploid spermatozoa (from 1.0 to 0.8%), but the differences were nonsignificant.

CONCLUSIONS

Discontinuous Percoll separation did increase the X:Y ratio significantly, but the enrichment of X-bearing spermatozoa is insufficient for clinical use in preconceptional sex selection.

Comparison of various methods of processing human cryopreserved-thawed semen samples

We compared the efficacy of various methods of processing cryopreserved-thawed samples for the recovery of functionally adequate spermatozoa as assessed by the response to the sperm stress test (SST), an index of temperature activated sperm membrane lipid peroxidation, and immediate and delayed changes in sperm viability and motion parameters. Donor semen samples (n = 28) were cryopreserved-thawed and divided into six equal parts, one part was used as control and the remaining parts were used to compare five methods of sperm processing as follows: direct Percoll gradient processing, washing by one-step or stepwise addition of the washing medium followed by Percoll processing, and washing by one-step or stepwise addition of the washing medium. Additional samples (n = 10) were evaluated for the immediate and delayed (6 h at 37 degrees C) impact of one-step and stepwise washing (without Percoll separation). Compared with wash-only methods, samples processed using Percoll had a significantly higher SST score (P = 0.001), motility, rapid spermatozoa (>50 microm/s), curvilinear velocity and motility index (P < 0.001). Comparing various Percoll methods, direct Percoll processing resulted in the highest number of motile spermatozoa recovered (P < 0.00001) and a higher SST score based on curvilinear velocity (P = 0.001). Stepwise washing gave a significantly higher number of motile spermatozoa (P < 0.001) but with a significantly lower SST score based on the concentration of motile spermatozoa (P = 0.001), motility (P = 0.001) and motility index (P = 0.01). Sperm viability and motion parameters after 6 h of incubation showed no difference between one-step and stepwise washing. In conclusion, compared with wash-only methods, Percoll processed samples resulted in the recovery of spermatozoa with superior quality as assessed by SST and motion analysis. One-step washing of the samples gave an overall comparable recovery compared to the samples prepared stepwise. Having significantly higher SST scores, similar viability and the maintenance of motility, one-step washing may be a better method of processing thawed samples than the stepwise washing.

Detection of endogenous digitalis-like immunoreactive factors in human blood

Digitalis-like immunoreactive factors (DLIF) are special types of steroids with lactone rings in their structures. Clinically, this type of compound can be used as medicine for heart failure; thus, the elevated endogenous DLIF found under certain pathological conditions are interferent substances in digoxin immunoassay. Endogenous DLIF with biological and immunological properties similar to cardiotonic drugs, such as digoxin, have been found in several tissues and body fluids of animals and humans. Since these endogenous Na+, K(+)-ATPase inhibitors can be considered hormones in nature, immunoassays must be selected detection of them to achieve the required sensitivity and specificity. In this study, we used three sets of in-house formulated immunoassays for DLIF and ouabain-like factors (OLF) detection. Using a polyclonal antibody-based ouabain enzyme immunoassay, the mean +/- S.E.M. of OLF in the sera of 10 healthy individuals were determined to be (9.1 +/- 0.9) x 10(-11) M. Using a monoclonal antibody-based ouabain enzyme immunoassay, the mean +/- S.E.M of OLF in the sera of 10 healthy individuals was (8.2 +/- 1.2) x 10(-11) M while using a antibody fragment Fab-based enzyme immunoassay for digoxin, the mean +/- S.E.M of DLIF in 11 healthy individuals was (4.0 +/- 1.2) x 10(-10) M. In conclusion, our immunological data indicate that DLIFs are normal constituents of human blood. Although DLIF is the major component, coexistence of OLF with DLIF in healthy individuals can not be excluded.

Effects of blocked atrial beats on the atrioventricular nodal recovery property: facilitation or depression?

INTRODUCTION

Blocked atrial beats (A(B)) usually have concealed AV nodal penetration, which can change the nodal conduction time (AH) of a subsequent beat. However, without an output marker it is difficult to assess their effect on the node. In this report we used all possible parameters as nodal resting time after A(B) and plotted them against the AH of testing beats to study their effects on the node.

METHODS AND RESULTS

Atrial extrastimulation studies were done in 21 patients in whom one blocked atrial beat (A(2B)) was observed. Nodal recovery curves were obtained for basic pacing (A1), after a conducted premature beat (A2), and after A(2B). In six patients there were 2 to 3 consecutively blocked beats (A(nB)) and recovery curves were constructed after each A(nB). Nodal recovery curves were plotted with AH of the testing beat against different nodal resting parameters and fitted to a single exponential equation. We found contradicting phenomena when using different formats. (1) For recovery curves of A(2B), there was a rightward shift from that of the basic curve when using H1A3 or A1A3 as the gauge (depression phenomenon). On the contrary, there was a leftward shift of the curves when using A(2B)A3 (facilitating phenomenon). (2) For recovery curves after multiple blocked beats there was a marked rightward shift of all curves except A(n-1)(B)An-curves, which were all leftward shifted.

CONCLUSION

Because these contradicting phenomena were dictated by the presenting formats, the terms "depression" and "facilitation" cannot be considered intrinsic AV nodal properties outside of the strict context of the pacing protocol and the format of data presentation.

Reproducibility of the revised American Fertility Society classification of endometriosis using laparoscopy or laparotomy

OBJECTIVE

To assess the discrepancy between laparoscopic and laparotomic scoring methods using the revised American Fertility Society (AFS) classification of endometriosis.

METHOD

In this prospective study, 84 patients with endometriosis were scored twice (laparoscopically and laparotomically) by the same subspecialty-certified reproductive endocrinologist. The magnitude of inter-method variability was reported quantitatively by the S.D. of the differences in scores between the pairs. The differences in the mean endometriosis scores between the two methods were assessed by the paired Student's t-test. P < 0.05 was considered as statistically significant. Discrepancy between the two methods in the staging of endometriosis patients was presented by kappa measure of agreement.

RESULT

There was considerable variability in the scores between the two scoring methods by the same observer. Among individual components of the scoring system, the greatest variability occurred in the ovarian endometriosis and cul-de-sac obliteration subscores, with the least variability observed for peritoneum endometriosis. The inter-method variation in score was sufficient to alter the endometriosis staging in 34.5% of patients, including a difference of two stages in 3.6% of patients. The kappa coefficient was 0.49, indicating fair-to-good agreement between the two scoring methods.

CONCLUSION

Inter-method variability between laparoscopic and laparotomic scoring methods was high for ovarian endometriosis subscore using the revised AFS classification of endometriosis. Agreement in endometriosis staging between the two methods was fair to good.

Functional characterization of naturally occurring variants of human hepatitis B virus containing the core internal deletion mutation

Naturally occurring variants of human hepatitis B virus (HBV) containing the core internal deletion (CID) mutation have been found frequently in HBV carriers worldwide. Despite numerous sequence analysis reports of CID variants in patients, in the past decade, CID variants have not been characterized functionally, and thus their biological significance to HBV infection remains unclear. We report here two different CID variants identified from two patients that are replication defective, most likely due to the absence of detectable core protein. In addition, we were unable to detect the presence of the precore protein and e antigen from CID variants. However, the production of polymerase appeared to be normal. The replication defect of the CID variants can be rescued in trans by complementation with wild-type core protein. The rescued CID variant particles, which utilize the wild-type core protein, presumably are enveloped properly since they can be secreted into the medium and band at a position similar to that of mature wild-type Dane particles, as determined by gradient centrifugation analysis. Our results also provide an explanation for the association of CID variants with helper or wild-type HBV in nature. The significance of CID variants in HBV infection and pathogenesis is discussed.

A defective interference-like phenomenon of human hepatitis B virus in chronic carriers

Defective interfering (DI) particles have been found in many RNA and DNA viruses of bacteria, plants, and animals since their first discovery in influenza virus. However, this fundamental phenomenon has not been demonstrated in human natural infections. Using a new approach, here we provide the first experimental evidence for the existence of DI-like viruses in human chronic carriers of hepatitis B virus (HBV). Functional characterization of naturally occurring core internal deletion (CID) variants of HBV revealed all of the features of DI particles. When equal amounts of wild-type and CID variant DNAs were cotransfected into a human hepatoma cell line, Huh7, a three- to fivefold enrichment of CID variants was most often observed. The fluctuations of the virus populations between CID variants and helper HBV in three chronic carriers are reminiscent of the cycling phenomenon in other DI viral systems. This finding has important implications for chronic viral hepatitis and other chronic progressive viral diseases.

PDP1, a novel Drosophila PAR domain bZIP transcription factor expressed in developing mesoderm, endoderm and ectoderm, is a transcriptional regulator of somatic muscle genes

In vertebrates, transcriptional control of skeletal muscle genes during differentiation is regulated by enhancers that direct the combinatorial binding and/or interaction of MEF2 and the bHLH MyoD family of myogenic factors. We have shown that Drosophila MEF2 plays a role similar to its vertebrate counterpart in the regulation of the Tropomyosin I gene in the development of Drosophila somatic muscles, however, unlike vertebrates, Drosophila MEF2 interacts with a muscle activator region that does not have binding sites for myogenic bHLH-like factors or any other known Drosophila transcription factors. We describe here the isolation and characterization of a component of the muscle activator region that we have named PDP1 (PAR domain protein 1). PDP1 is a novel transcription factor that is highly homologous to the PAR subfamily of mammalian bZIP transcription factors HLF, DBP and VBP/TEF. This is the first member of the PAR subfamily of bZIP transcription factors to be identified in Drosophila. We show that PDP1 is involved in regulating expression of the Tropomyosin I gene in somatic body-wall and pharyngeal muscles by binding to DNA sequences within the muscle activator that are required for activator function. Mutations that eliminate PDP1 binding eliminate muscle activator function and severely reduce expression of a muscle activator plus MEF2 mini-enhancer. These and previous results suggest that PDP1 may function as part of a larger protein/DNA complex that interacts with MEF2 to regulate transcription of Drosophila muscle genes. Furthermore, in addition to being expressed in the mesoderm that gives rise to the somatic muscles, PDP1 is also expressed in the mesodermal fat body, the developing midgut endoderm, the hindgut and Malpighian tubules, and the epidermis and central nervous system, suggesting that PDP1 is also involved in the terminal differentiation of these tissues.

Developmental changes of atrioventricular nodal recovery properties

Atrioventricular (AV) nodal recovery properties can be studied by a periodic premature stimulation protocol performed at a slow basic rate. Developmental aspects of these properties have not been determined. The purpose of this study was to determine the developmental changes of AV nodal recovery properties. Forty-three children and young adults (male:female ratio 25:18) without AV nodal disease (aged 3.3 to 21.9 years) were studied by delivering premature atrial extrastimuli coupled to basic driven atrial beats. The individual recovery curve was fitted to the equation: A2H2 = A0H0 + exp(alpha -H1A2/tau) for H1A2 > or =theta, where A0H0 is the minimum AH interval, H1A2 is any recovery interval that exceeds the nodal effective refractory period, A2H2 is the corresponding nodal conduction time at any given H1A2, alpha is a constant, tau is the recovery time constant, and theta is the nodal effective refractory period. We found that: (1) A0H0 and alpha constant did not change significantly with age; (2) both tau (r = 0.324; p <0.05) and theta (r = 0.401; p <0.05) had a positive correlation with age; and (3) the maximum change in A2H2 with a 10-ms decrement in H1A2 was 32 ms and did not change significantly with age. Our results suggest that AV nodal recovery properties are age-dependent and both the recovery time constant and effective refractory period lengthen with age.

A study of the growth changes in the maxillofacial skeleton of females with reversed occlusion: investigation by means of lateral x-ray cephalogram

321 females with reversed occlusion from the ages of 6 to 20 were classified into 15 groups according to chronological age, and the changes of maxillofacial skeleton accompanying growth were investigated. Lateral cephalometric roentgenogram before treatment of the subjects were used for analyses and measurements of maxillofacial skeleton and overjet. The cephalometric analysis was standardized on the S-N plane, and 5 angular items and 6 linear distances were examined. The results of the investigation are summarized as follows: (1) angle ANB, the relationship between the upper and lower jaws, deteriorated to a minus degree from the age of 9 and became -3.3 degrees at the age of 14. Skeletal convexity became negative from the same age and was -7.3 degrees at the age of 14. Thus, the abnormal skeletal features progressed in this condition. (2) The Ar-Gn distance measurement gradually increased from the age of 6 to 18. The increase was 16.2 mm from 7 to 12, an increase of 3.2 mm yearly. (3) A high correlation (r = 0.99) was observed between angle ANB and Convexity. As well, a high coefficient of correlation (r = 0.87) was observed between skeletal convexity and soft tissue convexity. The change in soft tissue convexity may occur 3-4 years later than that of skeletal convexity. (4) The growth curve of Ar-Gn became a logistic curve with the point of deflection at the age of 10.87. The growth curves of S-Gn and N-Me became logistic curves in the same way.

Determining when a clinical activity should be classified as research requiring Institutional Review Board Review

The boundary between therapy and research may at times be difficult to distinguish, and it is, therefore, important for health care professionals to recognize when a clinical activity should be properly classified as research. Research may be subject to federal regulations which require advance review and approval by an Institutional Review Board (IRB) in order to protect the rights and welfare of patients who serve as human subjects. This paper will discuss the criteria health care professionals can use to distinguish between therapy, innovative therapy, and therapeutic or clinical research.

Novel and frequent mutations of hepatitis B virus coincide with a major histocompatibility complex class I-restricted T-cell epitope of the surface antigen

We examined the full-length hepatitis B virus (HBV) envelope (surface antigen or HBV small surface antigen [HBsAg]) sequences of 12 different liver samples from 10 different hepatoma-containing chronic carriers. Surprisingly, novel and frequent mutations occurred predominantly at amino acids 40 and 47 of HBsAg, in addition to within a known protective B-cell epitope (so-called group a determinant of HBsAg 124-148). Approximately 58% of chronic carriers contain mutations at the group a determinant. The mutation frequency at the hotspot codons 40 and 47 is approximately 83%, 1 order of magnitude higher than at the known polymorphic sites of subtype-specific determinants at codons 122 and 160, which is approximately 4%. This new mutational domain is found to coincide with a major histocompatibility complex class I-restricted T-cell epitope. The potential biological significance of this novel mutation in the immunopathogenesis of HBV chronic carriers is discussed.

Prenatal diagnosis of cephalothoracopagus janiceps monosymmetros

We report a case of cephalothoracopagus janiceps monosymmetros that was diagnosed prenatally by ultrasound at 23 weeks' gestation. Obstetric ultrasound demonstrated conjoined female twins with a single fused cranial vault irregular in contour, duplicated cerebra, one face, two eyeballs, a fused thorax, two hearts, two thoracic spines, eight limbs, and polyhydramnios. The pregnancy was terminated and all the features described prenatally were observed at necropsy. The asymmetrical fused faces consisted of a ventral humanoid face with micrognathia, microphthalmia, low-set ears, a normal nose, and an opposite reduced face with partial facial features of a central narrowed fissure and paired synotic ears. The conjoined twins had fused umbilical cords, omphalocoele, and a single oesophagus, stomach, and duodenum, but duplicated pancreases, spleens, and central nervous, cardiopulmonary, hepatic, and genito-urinary systems. The common gastrointestinal tract bifurcated at the level of the jejunum. Our case documents a very uncommon variety of asymmetrical cephalothoracopagus janiceps with duplicated central nervous systems.

Ectopic expression of MEF2 in the epidermis induces epidermal expression of muscle genes and abnormal muscle development in Drosophila

Myocyte-specific enhancer-binding factor 2 (MEF2) is a myogenic regulatory factor in vertebrates and Drosophila. Whereas the role of MEF2 in regulating vertebrate myogenesis and muscle genes has been extensively studied, little is known of the role of MEF2 in regulating Drosophila myogenesis. We have shown in a recent analysis of the regulation of the Drosophila Tropomyosin I (TmI) gene in transgenic flies that MEF2 is a positive regulator of TmI expression in the somatic body-wall muscles of embryos, larvae, and adults. To understand further the role of MEF2 in myogenesis and test the role of MEF2 in regulating TmI expression, we have used the yeast GAL4/UAS system to generate embryos in which MEF2 is ectopically expressed in tissues where it is not normally expressed or embryos in which MEF2 is overexpressed in the mesoderm and muscles. We observe that ectopic expression of MEF2 in the epidermis and the ventral midline cells in embryos activates the expression of TmI and other muscle genes in these tissues and that this activation is stage-dependent suggesting a requirement for additional factors. Furthermore, ectopic expression of MEF2 in the epidermis results in a decrease in the expression of signaling molecules in the epidermis and a failure of the embryo to properly form body-wall muscles. These results indicate that MEF2 can function out of context in the epidermis to induce the expression of muscle genes and interfere with a requirement for the epidermis in muscle development. We also find that the level of MEF2 in the mesoderm and/or muscles in embryos is critical to body-wall muscle formation; however, no effect is observed on the development of the visceral muscle or dorsal vessel.

A high cholesterol, (n-3) polyunsaturated fatty acid diet induces hypercholesterolemia more than a high cholesterol (n-6) polyunsaturated fatty acid diet in hamsters

This study was designed to study the effects of (n-3) polyunsaturated fatty acids (PUFA) on plasma and liver lipids, particularly lipoprotein cholesterol concentrations, in hamsters. Diets rich in (n-3) PUFA (21 g/100 g fatty acid) or (n-6) PUFA (37.4 g/ 100 g fatty acid) with or without 5 g/kg cholesterol (C) supplements were given for 4 wk to male hamsters weighing 70-90 g. The VLDL- and (IDL + LDL)-cholesterol concentrations were 114 and 128% higher in hamsters fed the (n-3) PUFA + C diet than in those fed the (n-6) PUFA + C diet. However, these differences were not observed when cholesterol was not supplemented. Hamsters fed the (n-3) PUFA diet had significantly lower plasma and hepatic triglyceride concentrations than those fed the (n-6) PUFA diet. Concentrations were comparable in hamsters fed (n-6) PUFA + C and (n-3) PUFA + C. Hepatic cholesteryl esters were significantly lower, while hepatic microsomal acyl-CoA:cholesterol acyltransferase activity and VLDL cholesteryl esters were significantly higher in hamsters fed the (n-3) PUFA + C diet than in those fed the (n-6) PUFA + C diet. Our results demonstrate that elevation of VLDL- and (IDL + LDL)-cholesterol in hamsters by (n-3) PUFA, compared with (n-6) PUFA, is dependent on dietary cholesterol supplementation and may be due to decreased catabolism of these lipoproteins.