Prune belly syndrome in surviving males can be caused by Hemizygous missense mutations in the X-linked Filamin A gene

Background

Prune belly syndrome (PBS) is a rare, multi-system congenital myopathy primarily affecting males that is poorly described genetically. Phenotypically, its morbidity spans from mild to lethal, however, all isolated PBS cases manifest three cardinal pathological features: 1) wrinkled flaccid ventral abdominal wall with skeletal muscle deficiency, 2) urinary tract dilation with poorly contractile smooth muscle, and 3) intra-abdominal undescended testes. Despite evidence for a genetic basis, previously reported PBS autosomal candidate genes only account for one consanguineous family and single cases.

Methods

We performed whole exome sequencing (WES) of two maternal adult half-brothers with syndromic PBS (PBS + Otopalatodigital spectrum disorder [OPDSD]) and two unrelated sporadic individuals with isolated PBS and further functionally validated the identified mutations.

Results

We identified three unreported hemizygous missense point mutations in the X-chromosome gene Filamin A (FLNA) (c.4952 C > T (p.A1448V), c.6727C > T (p.C2160R), c.5966 G > A (p.G2236E)) in two related cases and two unrelated sporadic individuals. Two of the three PBS mutations map to the highly regulatory, stretch-sensing Ig19–21 region of FLNA and enhance binding to intracellular tails of the transmembrane receptor β-integrin 1 (ITGβ1).

Conclusions

FLNA is a regulatory actin-crosslinking protein that functions in smooth muscle cells as a mechanosensing molecular scaffold, transmitting force signals from the actin-myosin motor units and cytoskeleton via binding partners to the extracellular matrix. This is the first evidence for an X-linked cause of PBS in multiple unrelated individuals and expands the phenotypic spectrum associated with FLNA in males surviving even into adulthood.

On the stoichiometry of Deinococcus radiodurans Dps-1 binding to duplex DNA

DNA protection during starvation (Dps) proteins, dodecameric assemblies of four-helix bundle subunits, contribute to protection against reactive oxygen species. Deinococcus radiodurans, which is characterized by resistance to DNA damaging agents, encodes two Dps homologs, of which Dps-1 binds DNA with high affinity. DNA binding requires N-terminal extensions preceding the four-helix bundle core. Composed of six Dps-1 dimers, each capable of DNA binding by N-terminal extensions interacting in consecutive DNA major grooves, dodecameric Dps-1 would be predicted to feature six DNA binding sites. Using electrophoretic mobility shift assays and intrinsic tryptophan fluorescence, we show that dodecameric Dps-1 binds 22-bp DNA with a stoichiometry of 1:6, consistent with the existence of six DNA binding sites. The stoichiometry of Dps-1 binding to 26-bp DNA is 1:4, suggesting that two Dps-1 dodecamers can simultaneously occupy opposite faces of this DNA. Mutagenesis of an arginine (Arg132) on the surface of Dps-1 leads to a reduction in DNA binding. Altogether, our data suggest that duplex DNA lies along the dimer interface, interacting with Arg132 and the N-terminal α-helices, and they extend the hexagonal packing model for Dps-DNA assemblies by specifying the basis for occupancy of available DNA binding sites.

Estrogen-induced activation of extracellular signal-regulated kinase signaling triggers dendritic resident mRNA translation

Activated extracellular signal-regulated kinase (ERK) signaling mediated plasticity-related gene transcription has been proposed for one possible mechanism by which 17β-estradiol (E2) enhances synaptic plasticity and memory. Because activated ERK also enhances plasticity-related mRNA translation in the dendrites of neurons, we sought to determine the effects of E2 on activation of ERK, phosphorylation of translation initiation factors, and dendritic mRNA translation in hippocampal neurons. Acute E2 application resulted in a rapid, transient increase in phosphorylation of translation initiation factors, ribosomal protein (S6) and eIF4E binding protein1 (4EBP1), in an activated ERK-dependent manner. Since phosphorylation of these translation factors enhance mRNA translation, we tested E2's effect on dendritic mRNA translation. Using a green fluorescent protein (GFP)-based dendritic mRNA translation reporter (reporter plasmid construct consisted of a GFP gene fused to the 3' untranslated region (UTR) from CAMKIIα, which contains dendritic resident mRNA targeting and mRNA translational regulatory elements) we showed that E2 treatment resulted in increased somatic and dendritic GFP mRNA translation in GFP-reporter transfected hippocampal neurons. Translation inhibitor anisomycin and ERK inhibitor U0126 blocked E2 effects. Taken together, our results provide a novel mechanism by which E2 may trigger local protein synthesis of α-CaMKII in the dendrites, which is necessary for modulation of synaptic plasticity.

Preferential osmolyte accumulation: a mechanism of osmotic stress adaptation in diazotrophic bacteria

A common cellular mechanism of osmotic-stress adaptation is the intracellular accumulation of organic solutes (osmolytes). We investigated the mechanism of osmotic adaptation in the diazotrophic bacteria Azotobacter chroococcum, Azospirillum brasilense, and Klebsiella pneumoniae, which are adversely affected by high osmotic strength (i.e., soil salinity and/or drought). We used natural-abundance C nuclear magnetic resonance spectroscopy to identify all the osmolytes accumulating in these strains during osmotic stress generated by 0.5 M NaCl. Evidence is presented for the accumulation of trehalose and glutamate in Azotobacter chroococcum ZSM4, proline and glutamate in Azospirillum brasilense SHS6, and trehalose and proline in K. pneumoniae. Glycine betaine was accumulated in all strains grown in culture media containing yeast extract as the sole nitrogen source. Alternative nitrogen sources (e.g., NH(4)Cl or casamino acids) in the culture medium did not result in measurable glycine betaine accumulation. We suggest that the mechanism of osmotic adaptation in these organisms entails the accumulation of osmolytes in hyperosmotically stressed cells resulting from either enhanced uptake from the medium (of glycine betaine, proline, and glutamate) or increased net biosynthesis (of trehalose, proline, and glutamate) or both. The preferred osmolyte in Azotobacter chroococcum ZSM4 shifted from glutamate to trehalose as a consequence of a prolonged osmotic stress. Also, the dominant osmolyte in Azospirillum brasilense SHS6 shifted from glutamate to proline accumulation as the osmotic strength of the medium increased.

Role of Glycine Betaine and Related Osmolytes in Osmotic Stress Adaptation in Yersinia enterocolitica ATCC 9610

Yersinia enterocolitica is a gram-negative, food-borne pathogen that can grow in 5% NaCl and at refrigerator temperatures. In this report, the compatible solutes (osmolytes) which accumulate intracellularly and confer the observed osmotic tolerance to this pathogen were identified. In minimal medium, glutamate was the only detectable osmolyte that accumulated in osmotically stressed cells. However, when the growth medium was supplemented with glycine betaine, dimethylglycine, or carnitine, the respective osmolyte accumulated intracellularly to high levels and the growth rates of the osmotically stressed cultures improved from 2.4- to 3.5-fold. Chill stress also stimulated the intracellular accumulation of glycine betaine, but the growth rate was only slightly improved by this osmolyte. Both osmotic upshock and temperature downshock stimulated the rate of uptake of [(sup14)C]glycine betaine by more than 30-fold, consistent with other data indicating that the osmolytes are accumulated from the growth medium via transport.

Does usefulness of potassium supplementation depend on speed?

REASONS FOR PERFORMING STUDY

Electrolyte mixtures given to counter sweat loss usually contain abundant potassium. However, increases in plasma [K+] occur with exercise and supplementation may further increase plasma levels, potentially increasing the risk of neuromuscular hyperexcitability and development of adverse clinical sequellae. This proposition requires study.

OBJECTIVES

To compare effects of a K-rich electrolyte supplement (EM+K) to a K-free one (EM-K) on plasma [K+], [Ca++] and acid-base status during an endurance incremental exercise test on the treadmill.

METHODS

The test consisted of 3 bouts (simulating loops in an endurance race) of 12 km performed at 6, then 7, then 8 m/sec with 25 min rest stops (S1, S2) between loops on 13 endurance trained Arabian horses (7 EM-K, 6 EM+K). Electrolytes were supplied orally 60 mins before exercise (Pre) and at each stop. Blood samples were taken before exercise and during exercise, each S and 120 mins of recovery (R). Blood was analysed for pH, PCO2, packed cell volume (PCV), plasma [Na+], [K+], [Cl-], [Ca++], glucose, and lactate [La-]; plasma [H+] and osmolality (osm) were calculated. The dietary cation anion difference (DCAD) was calculated to be -27 meq/dose EM-K and 109 meq in EM+K, respectively.

RESULTS

Plasma [H+] decreased during the 6 and 7 m/sec loops, increased during the 8 m/sec loop, and returned to Pre at S1, S2 and R. Plasma [K+] was higher at 8 m/sec and plasma [Ca++] was overall lower in the EM+K group compared to EM-K. Other findings included higher overall PCV, overall glucose, and [La-] during the 8 m/sec loop (P<0.040) in EM+K compared to EM-K horses.

CONCLUSIONS

EM+K supplementation leads to higher plasma [K+] increasing the risk of neuromuscular hyperexcitability during exercise. Acute effects of a lower DCAD in EM-K may have led to higher plasma [Ca++]. Potassium-rich electrolytes may have triggered the release of epinephrine, contributing to higher PCV, glucose release and increased lactate production.

POTENTIAL RELEVANCE

Lower plasma [K+] and higher plasma [Ca++] with EM-K supplementation may help reduce the risk of conditions associated with neuromuscular hyperexcitability occurring especially during higher speeds in endurance races.

Co-targeting leptin and insulin-like growth factor I signaling: dramatic effects of epidermal growth factor receptor inhibitors on triple negative breast cancer cells

Abstract #3044

Introduction: Obesity is an independent risk factor for breast cancer and obese breast cancer patients exhibit a higher risk for larger tumor burden, increased metastasis and poor response to endocrine therapy. Obesity affects breast carcinogenesis by autocrine and paracrine effects of adipocytokine leptin and IGF-1. We have previously shown that leptin induces growth stimulation of breast cancer cells by recruiting histone acetyltransferases and mediator complex to cyclin D1 promoter via activation of Stat3. In the present study, we found a novel bidirectional crosstalk between IGF-1 and leptin signaling that promotes invasion and migration of triple-negative (ER, PR, HER2 negative) breast cancer cells; MDA-MB-231, MDA-MB-468, MDA-MB-435 and HCC-1806.&#x2028; Methods and Results: IGF-1 induced significant tyrosine phosphorylation of leptin receptor (Ob-Rb) and leptin induced tyrosine phosphorylation of IGF-1 Receptor (IGF-1R). Combined treatment of leptin and IGF-1 induced synergistic activation of both Ob-Rb and IGF-1R along with activation of Akt and ERK. Furthermore, IGF-1 and leptin synergistically transactivated epidermal growth factor receptor (EGFR) and induced proliferation of triple negative breast cancer cells. We also found that tyrosine phosphorylation of EGFR induced by combined treatment of leptin and IGF-1 was significantly inhibited not only by EGFR tyrosine kinase inhibitor, AG1478 but also with a broad-spectrum matrix metalloproteinase inhibitor, GM6001 indicating that leptin and IGF-1 induced EGFR transactivation is dependent on proteolytic release of EGFR ligands. Intriguingly, we also found that combined treatment of leptin and IGF-1 potently induced invasion of triple negative breast cancer cells in Matrigel invasion and quantitative Electric Cell-Substrate Impedance Sensing invasion assays. Inhibition of leptin and IGF-1 mediated EGFR activation using a highly potent, reversible inhibitor of HER1/EGFR tyrosine kinase, erlotinib or dual epidermal growth factor receptor (EGFR)/human EGFR-2 (HER2) kinase inhibitor, lapatinib effectively inhibited leptin and IGF-1 induced invasion. Also, inhibition of EGFR activation using erlotinib and lapatinib reduced leptin- and IGF-1-induced migration of triple negative breast cancer cells.&#x2028; Discussion: Taken together these data indicate a novel bidirectional crosstalk between leptin and IGF-1 signaling that transactivates EGFR and promotes metastatic properties, invasion and migration of triple negative breast carcinoma cells. Our novel findings indicate the possibility of using EGFR inhibitors erlotinib and lapatinib to counter the pro-cancerous effects of leptin and IGF-1 signaling in triple negative breast cancers.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3044.

Adiponectin activates tumor suppressor LKB1 and AMP-activated protein kinase signaling to inhibit malignant properties of breast cancer cells

Abstract #3067

Introduction: The prevalence of obesity in the developed world has reached epidemic proportions in recent years. Obese breast cancer patients exhibit a higher risk for metastasis, larger tumor burden and poorer response to endocrine therapy. Therefore, it is very important to understand the adverse effects of obesity on breast cancer in order to devise appropriate new approaches to their treatment. Obesity is considered an endocrine disorder and serum levels of adiponectin, an adipocytokine proposed to have therapeutic potential, get significantly lowered with obesity. More recently, low serum adiponectin levels were associated with increased risk and more aggressive phenotype (larger tumor size and high histological grade) of breast cancer in women. Recently, anti-proliferative and pro-apoptotic response of adiponectin was shown in breast cancer cells but the molecular mechanisms governing the anti-cancer effects of adiponectin largely remain unknown. In the present study, we found a novel mechanism underlying adiponectin action involving upregulation of tumor suppressor LKB1 and activation of AMPK (AMP-activated protein kinase) signaling to inhibit malignant properties of breast cancer cells.&#x2028; Methods and Results: Adiponectin inhibited malignant properties such as invasion and migration of breast cancer cells in matrigel invasion, scratch migration and quantitative Electric Cell-Substrate Impedance Sensing (ECIS) invasion and migration assays. Interestingly, adiponectin induced phosphorylation of AMPK at Thr 172 in breast cancer cells. Adiponectin treatment also affected downstream targets of mTOR signaling pathway, including decreased phosphorylation of p70S6K showing the involvement of mTOR-S6K axis. Intriguingly, we found that adiponectin increased the expression of tumor suppressor LKB1 in breast cancer cells. Co-immunoprecipitation assays revealed that LKB1 co-immunoprecipitated with tumor suppressor TSC2. Increase in expression of upstream kinase LKB1 might directly regulate adiponectin induced activation of AMPK. We also found that breast cancer cells transfected with wild-type LKB1 plasmids increased phosphorylation of AMPK and decreased phosphorylation of p70S6K showing decrease in mTOR activity. In contrast, breast cancer cells transfected with kinase dead LKB1 decreased phosphorylation of AMPK and increased activation of p70S6K.&#x2028; Discussion: Taken together these data indicate a novel crosstalk between adiponectin and tumor suppressor LKB1 that modulates AMPK-S6K axis and inhibits metastatic properties, invasion and migration of breast cancer cells. The influence of adipocytokine, adiponectin on breast carcinogenesis is just beginning to be elucidated and our study is the first to show the direct involvement of tumor suppressor genes LKB1 and TSC2 in anti-cancer effects of adiponectin.

Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 3067.

Liver unit admission following paracetamol overdose with concentrations below current UK treatment thresholds

BACKGROUND

It has been suggested that current UK thresholds for treating paracetamol overdose should be reduced, following case reports of patients developing fatal liver failure after presenting with paracetamol concentrations below these thresholds.

AIM

To determine the frequency of severe liver dysfunction following paracetamol overdose when paracetamol concentrations are below current UK antidote thresholds.

DESIGN

Retrospective case note review.

METHODS

Details were collected from all patients admitted to liver transplant units in Newcastle and Edinburgh with paracetamol-induced hepatotoxicity.

RESULTS

Of 696 patients admitted to the two liver units following paracetamol overdose, 14 presented between 4 and 15 h after overdose with paracetamol concentrations below current UK treatment thresholds (estimated annual population rate 0.15/million person-years). Over the period of study, >100 000 presentations with paracetamol overdose would be expected in the catchment populations for these liver units.

DISCUSSION

In view of the rarity of this event, this research does not suggest a need to lower the current thresholds for antidotal treatment.

DNA copy number gains in head and neck squamous cell carcinoma

Gene amplification, a common mechanism for oncogene activation in cancer, has been used as a tag for the identification of novel oncogenes. DNA amplification is frequently observed in head and neck squamous cell carcinoma (HNSCC) and potential oncogenes have already been reported. We applied restriction landmark genome scanning (RLGS) to study gene amplifications and low-level copy number changes in HNSCC in order to locate previously uncharacterized regions with copy number gains in primary tumor samples. A total of 63 enhanced RLGS fragments, indicative of DNA copy number changes, including gains of single alleles, were scored. Enhanced sequences were identified from 33 different chromosomal regions including those previously reported (e.g. 3q26.3 and 11q13.3) as well as novel regions (e.g. 3q29, 8q13.1, 8q22.3, 9q32, 10q24.32, 14q32.32, 17q25.1 and 20q13.33). Furthermore, our data suggest that amplicons 11q13.3 and 3q26.3-q29 may be divided into possibly two and three independent amplicons, respectively, an observation supported by published microarray expression data.

Differential targets of CpG island hypermethylation in primary and metastatic head and neck squamous cell carcinoma (HNSCC)

Head and neck squamous cell carcinomas (HNSCC) often metastasise to the cervical lymph nodes. It is known for HNSCC as well as other cancers that progression from normal tissue to primary tumour and finally to metastatic tumour is characterised by an accumulation of genetic mutations. DNA methylation, an epigenetic modification, can result in loss of gene function in cancer, similar to genetic mutations such as deletions and point mutations. We have investigated the DNA methylation phenotypes of both primary HNSCC and metastatic tumours from 13 patients using restriction landmark genomic scanning (RLGS). With this technique, we were able to assess the methylation status of an average of nearly 1300 CpG islands for each tumour. We observed that the number of CpG islands hypermethylated in metastatic tumours is significantly greater than what is found in the primary tumours overall, but not in every patient. Interestingly, the data also clearly show that many loci methylated in a patient's primary tumour are no longer methylated in the metastatic tumour of the same patient. Thus, even though metastatic HNSCC methylate a greater proportion of CpG islands than do the primary tumours, they do so at different subsets of loci. These data show an unanticipated variability in the methylation state of loci in primary and metastatic HNSCCs within the same patient. We discuss two possible explanations for how different epigenetic events might arise between the primary tumour and the metastatic tumour of a person.

Osmosensing and osmoregulatory compatible solute accumulation by bacteria

Bacteria inhabit natural and artificial environments with diverse and fluctuating osmolalities, salinities and temperatures. Many maintain cytoplasmic hydration, growth and survival most effectively by accumulating kosmotropic organic solutes (compatible solutes) when medium osmolality is high or temperature is low (above freezing). They release these solutes into their environment when the medium osmolality drops. Solutes accumulate either by synthesis or by transport from the extracellular medium. Responses to growth in high osmolality medium, including biosynthetic accumulation of trehalose, also protect Salmonella typhimurium from heat shock. Osmotically regulated transporters and mechanosensitive channels modulate cytoplasmic solute levels in Bacillus subtilis, Corynebacterium glutamicum, Escherichia coli, Lactobacillus plantarum, Lactococcus lactis, Listeria monocytogenes and Salmonella typhimurium. Each organism harbours multiple osmoregulatory transporters with overlapping substrate specificities. Membrane proteins that can act as both osmosensors and osmoregulatory transporters have been identified (secondary transporters ProP of E. coli and BetP of C. glutamicum as well as ABC transporter OpuA of L. lactis). The molecular bases for the modulation of gene expression and transport activity by temperature and medium osmolality are under intensive investigation with emphasis on the role of the membrane as an antenna for osmo- and/or thermosensors.

Expression of a truncated keratin 5 may contribute to severe palmar--plantar hyperkeratosis in epidermolysis bullosa simplex patients

Epidermolysis bullosa simplex are dominant disorders of skin fragility characterized by intraepidermal blistering upon mild mechanical trauma. Skin fragility is caused by expression of either an abnormal keratin 5 or an abnormal keratin 14 protein, which compromises the structure and function of the keratin cytoskeleton of basal cells. We report an epidermolysis bullosa simplex patient with a novel single base substitution (A-->T1414) that changes the lysine residue at amino acid 472 to a non-sense codon (K472X). This change predicts the synthesis of a truncated keratin 5, missing 119 amino acids, including the entire tail domain and the highly conserved KLLEGE motif at the carboxy terminus of the 2B domain of the central rod. Expression of an altered keratin 5, of predicted mass and pI for the product of the K472X allele, was documented by one- and two-dimensional western blots of protein extracts from patient skin. Ultrastructural analysis of the patient's nonhyperkeratotic skin was remarkable for basal keratinocytes with dense and irregular keratin filaments proximal to the basement membrane. Keratinocytes, transfected with a cDNA carrying the A-->T1414 non-sense mutation, overexpressed a truncated keratin 5, and showed a disorganized and collapsed keratin filament cytoskeleton. This is the second epidermolysis bullosa simplex patient reported with a premature termination mutation in the KLLEGE motif. The remarkable occurrence of severe palmar--plantar hyperkeratosis in both patients suggests that the keratin 5 tail domain may have unrecognized, but important, normal functions in palmar-plantar tissues.

Dose effects of secobarbital in a Sternberg memory scanning task

Mean reaction times obtained in a Sternberg memory-scanning task were examined for the effects of secobarbital at two doses (1.47 mg/kg and 2.94 mg/kg) spanning the dose range commonly used in clinical practice. Both doses slowed reaction time significantly, with a more pronounced effect at the higher dose. The discriminability of the probe stimulus interacted with the barbiturate, producing a hyperadditive effect on reaction time, but only at the high dose. There were no other significant interaction effects involving the drug. These data are interpreted as additional support for an hypothesis localizing the effects of secobarbital to stimulus-encoding stages in the reaction process.

Mitochondrial ultrastructure in embryos after implantation

Information on the morphology of mitochondria during embryogenesis is scattered in the literature, but there appears to be a consistent pattern. During early organogenesis, the embryo is in a state of relative hypoxia associated with a major decrease in terminal electron transport system activity and a marked increase in anaerobic glycolysis. Ultrastructural studies of a 14-somite monkey embryo and day 10 and 12 rat embryos, together with a review of the literature, led us to determine that this hypoxic stage is characterized by vesiculation of the mitochondrial inner membranes, or cristae. Starting in the late morula stage and continuing during early postimplantation embryogenesis, the cristae increase but appear tubular or vesicular. After the end of neurulation, and with the onset of vascular perfusion of embryonic tissues, the cristae gradually become lamellated; by the limb bud stage they appear more mature. We suggest that new cristae derive from blebs of the inner mitochondrial membrane and that with maturation these blebs collapse, giving them a lamelliform appearance. The delamellated state of the cristae might inactivate oxidative phosphorylation to protect the embryo from toxic respiratory end-products that could accumulate in an embryo before there is vascular perfusion. Consistent with this hypothesis, mitochondrial diameters in the developing heart of monkey and rat embryos were approximately twice those found in skin and neural tube.

Expression of transglutaminase activity in developing human epidermis

Epidermal transglutaminase (TGase) is known to catalyse cross-linking of several precursor proteins in the formation of cornified cell envelope at the terminal differentiation of keratinocytes. Expression of TGase activity was studied using an in situ TGase activity assay in human fetal skin samples of 49-163 days estimated gestational age (EGA). In the early two-layered epidermis (49-56 days EGA), in situ TGase activity was not observed in the periderm cells or the basal cells. In the late two-layered epidermis (57-65 days EGA), in situ TGase activity became weakly positive in the periderm cells, but not in the basal cells. In the three-layered (66-95 days EGA) and in four- or more layered (96-135 days EGA) stratified epidermis, in situ TGase activity was still restricted only to the periderm cells. After keratinization occurred in the interfollicular epidermis (163 days EGA), in situ TGase activity was expressed in the granular and cornified layers. This unique localization of TGase activity further support the hypothesis that periderm cells form cornified cell envelope during their regression process in human fetal skin development.

Changing patterns of localization of putative stem cells in developing human hair follicles

In rodents, the hair follicle stem cells lie in a well-defined bulge in the outer root sheath; however, the bulge as a stem cell site of human hair follicle epithelium is still controversial. Epidermal stem cells are thought to express high levels of beta1 integrin and low levels of E-cadherin and beta- and gamma-catenin. In order to clarify the ontogenic distribution of possible stem cells during hair follicle development, the expression patterns of beta1 integrin subunits, E-cadherin, and beta- and gamma-catenins in the skin samples from human fetuses of a series of estimated gestational ages (EGA) were examined. beta1 integrin-rich, E-cadherin-, and beta- and gamma-catenin-poor cells, possible stem cells, were localized to the entire hair germ (65-84 d EGA) and later to the outermost cells of hair peg (85-104 d EGA). In the bulbous hair peg (105-135 d EGA) and in the differentiated lanugo hair follicle (>135 d EGA), they were settled in the bulge and the outermost layer of the outer root sheath. This sequential localization was similar to that of cells rich in epidermal growth factor receptor expression and positive with keratin 19, a putative marker of epidermal stem cells. In addition, these beta1 integrin-rich, E-cadherin-, and beta- and gamma-catenin-poor cells showed similar, undifferentiated morphologic features by electron microscopy. This information of ontogenic localization of possible hair follicle stem cells contributes to the further understanding of mechanisms of human hair follicle morphogenesis and supports the idea that the human fetal hair follicle bulge is a site of stem cells for follicular epithelium.

Partial COL1A2 gene duplication produces features of osteogenesis imperfecta and Ehlers-Danlos syndrome type VII

Type I collagen is the most abundant structural protein in the mammalian body. It exists as a heterotrimer of two subunits in the form [alpha1(I)]2alpha2(I). Pathogenic mutations in COL1A1 and COL1A2, the genes that encode the two subunits, cause a range of phenotypes including mild to lethal forms of osteogenesis imperfecta and a restricted set of Ehlers-Danlos syndrome phenotypes. Lethal mutations usually result from missense mutations that disrupt the normal triple helical structure of the molecule. Multi-exon duplication or deletion in type I collagen genes has rarely been observed and has generally resulted in a lethal or severe phenotype. We report a partial duplication in the COLIA2 gene that causes a relatively mild phenotype, despite the addition of 477 amino acids to the triple helical domain of the proalpha2(I) chain. The abnormal molecule is synthesized and secreted by cultured dermal fibroblasts in a normal fashion. Electron microscopy of dermal tissue reveals small but otherwise near normal collagen fibrils. The gene duplication occurred by mitotic sister chromatid exchange in the mother who is mosaic for the duplication allele. Examination of the abnormal sequence suggests a means by which the duplicated molecule could be processed and properly incorporated into mature collagen fibrils.

Trichodysplasia spinulosa--a newly described folliculocentric viral infection in an immunocompromised host

This is a case report of an immunocompromised individual who presented with progressive alopecia, friable follicular spinous processes, and erythematous, indurated papules. Examination of skin biopsies using light microscopy and immunohistochemistry revealed pathologic changes of the follicular inner root sheath epithelium with dystrophic trichohyaline granules. Electron microscopy of thin sections of tissue revealed intracellular viral particles with a size and appearance consistent with those in the Papovaviridae family. Electron microscopy of negatively stained extract from a homogenized lesion also demonstrated icosahedral viruses with papovavirus morphology. We believe this is a previously unreported folliculocentric viral infection in an immunosuppressed human host and have termed this entity "trichodysplasia spinulosa".

The calcium-activated neutral protease calpain I is present in normal foetal skin and is decreased in neonatal harlequin ichthyosis

Calcium concentration is a critical factor for epidermal differentiation and is implicated in the expression and post-translational modification of numerous proteins in suprabasal cells of the epidermis. Calpains (calcium-activated neutral proteases) are believed to participate in signal transduction via highly regulated cytoplasmic protease activity. Here we investigate the expression of calpain I in normal human skin development and in neonatal harlequin ichthyosis (HI), a disorder of altered epidermal differentiation, especially the transition from the granular to the fully differentiated cornified layer. Calpain I was detected in developing foetal epidermis at 54 days estimated gestational age in the basal layer and the periderm of the developing foetal epidermis. By 125 days, calpain I was also detected in the granular layer. This pattern was maintained in newborn skin, but expression was significantly weaker in HI biopsies (n = 7). Reduced expression of calpain was specific to HI and was not observed in other skin diseases. Calpain was also normally expressed in the outer root sheath of hair follicles, in sebaceous glands and in sweat ducts and glands. Immunoblots of epidermal and keratinocyte extracts showed that the 78-kDa and 76-kDa active forms were generated via limited proteolysis of the 80-kDa inactive subunit; however, all forms were diminished in HI, consistent with findings in tissue sections. Our results show that calpain is present throughout the epidermis and is expressed from the early stages of development. These findings implicate calcium-mediated signalling events in the alteration of differentiation that occurs in HI.

Outcome after surgical repair of junctional epidermolysis bullosa-pyloric atresia syndrome: a report of 3 cases and review of the literature

BACKGROUND

Junctional epidermolysis bullosa-pyloric atresia syndrome is recognized as a distinct autosomal recessive entity. Affected infants present with skin fragility and inability to feed due to intestinal obstruction. Despite successful surgical repair of the anatomical defect, the outcome is poor owing to poor feeding, malabsorption, failure to thrive, and sepsis.

OBSERVATIONS

In 70 cases of intestinal obstruction and epidermolysis bullosa reported in the medical literature and the 3 reported here, surgical intervention was attempted 51 times. In all except 16 infants, death occurred before age 11 months (mean age, 70 days). Renal involvement and continued failure to thrive accompanied the skin disease in survivors, who ranged in age from 30 days to 16 years (mean age, 4.0 years).

CONCLUSIONS

The poor prognosis of this condition must be considered when decisions are made regarding surgical correction. Attempting surgical correction may be warranted in individual circumstances, but withholding surgical intervention and providing palliative support is an acceptable alternative.

Identification of an ATP-driven, osmoregulated glycine betaine transport system in Listeria monocytogenes

The ability of the gram-positive, food-borne pathogen Listeria monocytogenes to tolerate environments of elevated osmolarity and reduced temperature is due in part to the transport and accumulation of the osmolyte glycine betaine. Previously we showed that glycine betaine transport was the result of Na(+)-glycine betaine symport. In this report, we identify a second glycine betaine transporter from L. monocytogenes which is osmotically activated but does not require a high concentration of Na(+) for activity. By using a pool of Tn917-LTV3 mutants, a salt- and chill-sensitive mutant which was also found to be impaired in its ability to transport glycine betaine was isolated. DNA sequence analysis of the region flanking the site of transposon insertion revealed three open reading frames homologous to opuA from Bacillus subtilis and proU from Escherichia coli, both of which encode glycine betaine transport systems that belong to the superfamily of ATP-dependent transporters. The three open reading frames are closely spaced, suggesting that they are arranged in an operon. Moreover, a region upstream from the first reading frame was found to be homologous to the promoter regions of both opuA and proU. One unusual feature not shared with these other two systems is that the start codons for two of the open reading frames in L. monocytogenes appear to be TTG. That glycine betaine uptake is nearly eliminated in the mutant strain when it is assayed in the absence of Na(+) is an indication that only the ATP-dependent transporter and the Na(+)-glycine betaine symporter occur in L. monocytogenes.

Epimorphin expression during human foetal hair follicle development

Epimorphin is a mesenchymal protein expressed in several organs and known to have an essential role in epithelial tissue organization, including hair follicle morphogenesis, in mice. Although about 90% homology has been reported between human and mouse epimorphin exon sequences, there is no information about expression and function of epimorphin in hair follicle development in humans. In order to elucidate the expression pattern of epimorphin in human hair follicle morphogenesis and to compare it with the distribution of tenascin and neural cell adhesion molecule (NCAM), skin samples from human foetuses of a series of estimated gestational ages (EGAs) (46-168 days EGA) were studied using monoclonal anti-epimorphin antibody MC-1, anti-tenascin antibody and anti-human NCAM antibody. Epimorphin was detected in the mesenchymal cell condensation at the pregerm stage (< 75 days EGA), and there was strong expression of epimorphin in the perifollicular mesenchymal cells around the hair germ (75-84 days EGA). At the hair peg stage (85-104 days EGA), epimorphin was around the hair peg with the strongest staining in the neck portion. This sequence of staining patterns was similar to that of tenascin. In the bulbous hair peg (105-134 days EGA), the perifollicular dermal mesenchymal cells were evenly positive for epimorphin. Mesenchymal cells underneath the follicle bulb prior to formation of the dermal papilla were also positive for epimorphin. In the lanugo hair follicle (> 134 days EGA), dermal papilla cells expressed epimorphin as well as tenascin and NCAM. These results indicate that epimorphin expression is closely linked to developing hair follicles in human foetuses. This suggests that epimorphin may have an important part in induction of morphogenesis during human foetal hair follicle development.

Elevated retinoic acid receptor beta(4) protein in human breast tumor cells with nuclear and cytoplasmic localization

The transcription factor retinoic acid receptor beta(2) (RARbeta(2)) is a potent inhibitor of breast cancer cells in vitro, and studies suggest that RARbeta expression is lost in primary breast cancer. Although RARbeta(2) is selectively down-regulated at the mRNA level in breast tumor cells, we show that expression of an RARbeta protein is elevated in five of five breast tumor cell lines relative to normal human mammary epithelial cells. Subsequent analysis identified this protein as the translation product of the human RARbeta(4) transcript. Unlike the previously characterized mouse RARbeta(4) isoform, the human RARbeta(4) retains only half of a DNA-binding domain and lacks a ligand-independent transactivation domain at its N terminus. The RARbeta(4) protein localizes to the cytoplasm and to subnuclear compartments that resemble nuclear bodies. The structure and preliminary characterizations of human RARbeta(4), coupled with the observation that its expression is greatly elevated in breast tumor cell lines, support the hypothesis that RARbeta(4) functions as a dominant-negative repressor of RAR-mediated growth suppression.

Periderm cells form cornified cell envelope in their regression process during human epidermal development

Terminally differentiated stratified squamous epithelium forms a lining of the plasma membrane called the cornified cell envelope, a thick layer of several covalently cross-linked precursor proteins including involucrin, small proline-rich proteins, and loricrin. Their cross-linking isodipeptide bonds are formed by epidermal transglutaminases 1-3. Material from lamellar granules is attached on the extracellular surface of corneocytes during the keratinization process. The formation of cornified cell envelope and sequential expression of major cornified cell envelope precursor proteins, transglutaminases, and 25 kDa lamellar granule-associated protein were studied in human embryonic and fetal skin. Ultrastructurally, membrane thickening has already started in periderm cells of the two-layered epidermis and an electron-dense, thickened cell envelope similar to cornified cell envelope in adult epidermis is observed in periderm cells at the three-layered and later stages of skin development. In the two-layered epidermis (49-65 d estimated gestational age), immunoreactivities of involucrin, small proline-rich proteins, all the transglutaminases, and lamellar granule-associated protein were present only in the periderm. In the three-layered epidermis and thereafter (66-160 d estimated gestational age), loricrin became positive in the periderm cells, transglutaminases extended to the entire epidermis, and lamellar granule-associated protein was detected in intermediate cells as well as periderm cells. Immunoelectron microscopy demonstrated that both major cornified cell envelope precursor proteins, involucrin and loricrin, were restricted to the cornified cell envelope in periderm cells at this stage of development. After 160 d estimated gestational age, the periderm had disappeared and cornified cell envelope proteins and lamellar granule-associated proteins were expressed in the spinous, granular, and cornified cells and transglutaminases were detected in the entire epidermis. These findings indicate that cornified cell envelope precursor proteins, transglutaminases, and lamellar granule-associated proteins are expressed in coordination in periderm cells during human epidermal development and suggest that periderm cells form cornified cell envelope in the process of regression.

Ontogeny and regional variability of keratin 2e (K2e) in developing human fetal skin: a unique spatial and temporal pattern of keratin expression in development

Keratin 2e (K2e) is expressed in the upper spinous and granular cells of adult epidermis. A highly specific polyclonal antibody was made against a C-terminal peptide of K2e and used to observe K2e expression at different developmental stages. At 12.5 weeks estimated gestational age (EGA) K2e was detected in trunk skin in scattered cells in the intermediate layer. At 13.5 weeks EGA, greater numbers of intermediate cells were stained with variable intensity, and staining in this pattern increased with age. Epidermal sheets from 14 weeks EGA showed that K2e + cells were excluded from developing hair follicles. At 135 days EGA, the following regional patterns were observed: in cheek, trunk, dorsal and ventral knee, elbow and dorsal hand there was moderate to intense staining of upper intermediate keratinocytes excluding cells of the hair canals and sweat ducts. The periumbilical region distinctly lacked K2e staining, while more distal areas showed increasing numbers of K2e + cells. The earliest expression of K2e was at 10 weeks EGA in the presumptive nail bed of developing digits. By 13.5 weeks EGA this pattern had shifted to the proximal nail fold, and K2e was absent in the nail bed. K2e was excluded from developing sweat glands and ducts and from developing hair follicles at the hair germ and early peg stages. By 15 weeks EGA in the fetal hair follicle small groups of cells were K2e + and by 19 weeks K2e + cells were seen at the level of the matrix. Some overlap in staining was detected for K2e with K10, and in palmar skin with K9; however, mostly the filamentous staining patterns for these keratins were distinctive. This study shows that the complex patterns of temporal and regional expression of K2e differ from known patterns for other epidermal keratins and suggest different regulation and function for this epidermal keratin.

Cyclic ichthyosis with epidermolytic hyperkeratosis: A phenotype conferred by mutations in the 2B domain of keratin K1

Bullous congenital ichthyosiform erythroderma (BCIE) is characterized by blistering and erythroderma in infancy and by erythroderma and ichthyosis thereafter. Epidermolytic hyperkeratosis is a hallmark feature of light and electron microscopy. Here we report on four individuals from two families with a unique clinical disorder with histological findings of epidermolytic hyperkeratosis. Manifesting erythema and superficial erosions at birth, which improved during the first few months of life, affected individuals later developed palmoplantar hyperkeratosis with patchy erythema and scale elsewhere on the body. Three affected individuals exhibit dramatic episodic flares of annular, polycyclic erythematous plaques with scale, which coalesce to involve most of the body surface. The flares last weeks to months. In the interim periods the skin may be normal, except for palmoplantar hyperkeratosis. Abnormal keratin-filament aggregates were observed in suprabasal keratinocytes from both probands, suggesting that the causative mutation might reside in keratin K1 or keratin K10. In one proband, sequencing of K1 revealed a heterozygous mutation, 1436T-->C, predicting a change of isoleucine to threonine in the highly conserved helix-termination motif. In the second family, a heterozygous mutation, 1435A-->T, was found in K1, predicting an isoleucine-to-phenylalanine substitution in the same codon. Both mutations were excluded in both a control population and all unaffected family members tested. These findings reveal that a clinical phenotype distinct from classic BCIE but with similar histology can result from K1 mutations and that mutations at this codon give rise to a clinically unique condition.

Ultrastructural study of mitochondria and their cristae in embryonic rats and primate (N. nemistrina)

Information on the morphology of mitochondria during embryogenesis is scattered in the literature but there appears to be a developmental pattern characterized by vesiculation of the mitochondrial cristae. During early organogenesis, the embryo is in a relative state of hypoxia and this is associated with decrease of terminal electron transport system activity and a marked increase in glycolysis. Ultrastructural studies of a 14 somite monkey embryo, and day 10 and 12 rat embryos, along with a review of the literature led us to determine that this hypoxic stage is characterized by vesiculation of the mitochondrial cristae. Starting in the late morula stage and continuing during early postimplantation embryogenesis the cristae increase and appear tubular or vesicular. After the end of neurulation, and with onset of vascular perfusion, the cristae gradually become lamellated and by the limb bud stage appear more mature. We suggest that new cristae form from blebs of the inner mitochondrial membrane and that subsequently with maturation these blebs collapse giving them a lamelliform appearance. The delamellated state of the cristae may protect the embryo from toxic respiratory end-products of oxidative respiration which could accumulate in an embryo lacking vascular perfusion. In the heart of monkey and rat embryos, the mitochondria had diameters which were approximately twice those found in skin and neural tube.

Regional difference in expression of characteristic abnormality of harlequin ichthyosis in affected fetuses

Harlequin ichthyosis (HI) is a severe congenital ichthyosis in which newborn infants are covered with a thick plate of stratum corneum. We examined skin specimens from a variety of regions of the body including the scalp, face, tongue, trunk, upper and lower extremities, digits, palms, and soles of three fetuses affected with HI that were diagnosed prenatally. In all the skin regions, characteristic morphological abnormalities (absent or abnormal lamellar granules and intercellular lamellae, lipid inclusions in the cornified cells) were expressed in the late second trimester of the fetal period. The cornified cells in hair canals showed morphological abnormalities of HI more strongly than the interfollicular epidermis. Immunoblot study of epidermal extracts revealed that profilaggrin was much more prominent than filaggrin in all the hairy skin regions where the hair canals were extensively keratinized, but filaggrin was prominent in the palm. These observations support the idea that, in the hairy skin, HI phenotype expression is associated with keratinization and abnormal filaggrin metabolism in hair. In addition, the prenatal diagnosis or prenatal exclusion of HI is thought to be possible from whichever site of the fetal body the skin biopsy is taken in the late second trimester of the fetal period.

A topographic study of ERPs elicited by visual feature discrimination

The functional properties and topographic distribution of event-related potential (ERP) components elicited by visual discrimination of orientation, spatial frequency, spatial location, and color were investigated. ERPs were recorded from 28 electrode sites from 16 adult subjects. Five ERP components were measured: N1 (peak latency = 160 ms), P2 (250 ms), anterior N2 (260 ms), posterior N2 (280 ms), and P3 (400 ms). N1 and P2 were more negative when a stimulus was a target, showing the selection negativity effect. Feature-specific effects on component amplitude or topography varied by component. N1 and P2 were sensitive to stimulus orientation and location. Anterior or posterior N2 was sensitive to orientation, spatial frequency, and location. P3 varied with orientation, but not with other stimulus features. Cross-task comparisons of ERPs to vertical line segments in the color, orientation, and location discrimination tasks indicated that P2 and N2, but not N1 and P3, were sensitive to changes in task-demand. These data provide topographic evidence that ERP components in the 160-400 ms time domain can be differentiated on the basis to processing of specific visual features, and reflect neurophysiologically distinct visual pathways in the human cortex.

Topography of amphiregulin expression in cultured human keratinocytes: colocalization with the epidermal growth factor receptor and CD44

Much of the autonomous growth of cultured keratinocytes is attributable to the signaling of amphiregulin, a heparin-binding autocrine growth factor, through the epidermal growth factor receptor. Emerging evidence suggests, moreover, that the membrane proteoglycan, CD44, is a cofactor for the interaction of heparin-binding ligands with their receptors. This model was evaluated by characterizing the patterns of the immunolabeled molecules in cultured human neonatal keratinocytes, to test the hypothesis that involvement in a common function results in coordinate segregation within or on the cell. The molecules were localized by double immunofluorescence labeling to detect amphiregulin and either the epidermal growth factor receptor or CD44, and the immunostained products were imaged by scanning laser confocal microscopy. Both amphiregulin and the epidermal growth factor receptor segregated to a perinuclear distribution and to intercellular contacts. In addition, amphiregulin localized to the outer leading edge of colonies and focally to intranuclear sites. Metabolic blockade of proteoglycan sulfation with sodium chlorate inhibited growth of the cells and concurrently enhanced the nuclear, but decreased the outer leading edge, labeling for amphiregulin. There was no nuclear or perimeter labeling for the epidermal growth factor receptor. Cultures co-immunolabeled for CD44 and amphiregulin exhibited variable perinuclear staining for both, but otherwise CD44 was distributed to intercellular contacts. The intercellular localizations of CD44 with amphiregulin and of amphiregulin with the epidermal growth factor receptor were strongly concordant. These data are consistent with a concerted function at intercellular contacts, where cytokine signaling is mediated via receptor binding and possibly regulated by the CD44 proteoglycan as cofactor. The intranuclear and perimeter labeling of amphiregulin, however, suggests that this cytokine has additional functions, both in the nucleus and as a matrix receptor.

Mice that lack thrombospondin 2 display connective tissue abnormalities that are associated with disordered collagen fibrillogenesis, an increased vascular density, and a bleeding diathesis

Thrombospondin (TSP) 2, and its close relative TSP1, are extracellular proteins whose functions are complex, poorly understood, and controversial. In an attempt to determine the function of TSP2, we disrupted the Thbs2 gene by homologous recombination in embryonic stem cells, and generated TSP2-null mice by blastocyst injection and appropriate breeding of mutant animals. Thbs2-/- mice were produced with the expected Mendelian frequency, appeared overtly normal, and were fertile. However, on closer examination, these mice displayed a wide variety of abnormalities. Collagen fiber patterns in skin were disordered, and abnormally large fibrils with irregular contours were observed by electron microscopy in both skin and tendon. As a functional correlate of these findings, the skin was fragile and had reduced tensile strength, and the tail was unusually flexible. Mutant skin fibroblasts were defective in attachment to a substratum. An increase in total density and in cortical thickness of long bones was documented by histology and quantitative computer tomography. Mutant mice also manifested an abnormal bleeding time, and histologic surveys of mouse tissues, stained with an antibody to von Willebrand factor, showed a significant increase in blood vessels. The basis for the unusual phenotype of the TSP2-null mouse could derive from the structural role that TSP2 might play in collagen fibrillogenesis in skin and tendon. However, it seems likely that some of the diverse manifestations of this genetic disorder result from the ability of TSP2 to modulate the cell surface properties of mesenchymal cells, and thus, to affect cell functions such as adhesion and migration.

Ehlers-Danlos syndrome type VIIA and VIIB result from splice-junction mutations or genomic deletions that involve exon 6 in the COL1A1 and COL1A2 genes of type I collagen

Ehlers-Danlos syndrome (EDS) type VII results from defects in the conversion of type I procollagen to collagen as a consequence of mutations in the substrate that alter the protease cleavage site (EDS type VIIA and VIIB) or in the protease itself (EDS type VIIC). We identified seven additional families in which EDS type VII is either dominantly inherited (one family with EDS type VIIB) or due to new dominant mutations (one family with EDS type VIIA and five families with EDS type VIIB). In six families, the mutations alter the consensus splice junctions, and, in the seventh family, the exon is deleted entirely. The COL1A1 mutation produced the most severe phenotypic effects, whereas those in the COL1A2 gene, regardless of the location or effect, produced congenital hip dislocation and other joint instability that was sometimes very marked. Fractures are seen in some people with EDS type VII, consistent with alterations in mineral deposition on collagen fibrils in bony tissues. These new findings expand the array of mutations known to cause EDS type VII and provide insight into genotype/phenotype relationships in these genes.

CCAAT/enhancer binding protein epsilon is preferentially up-regulated during granulocytic differentiation and its functional versatility is determined by alternative use of promoters and differential splicing

CCAAT/enhancer binding protein (C/EBP) epsilon is a recently cloned member of the C/EBP family of transcription factors and is expressed exclusively in cells of hematopoietic origin. The human C/EBPepsilon gene is transcribed by two alternative promoters, Palpha and Pbeta. A combination of differential splicing and alternative use of promoters generates four mRNA isoforms, of 2.6 kb and 1.3-1.5 kb in size. These transcripts can encode three proteins of calculated molecular mass 32.2 kDa, 27.8 kDa, and 14.3 kDa. Accordingly, Western blots with antibodies specific for the DNA-binding domain, that is common to all forms, identify multiple proteins. C/EBPepsilon mRNA was greatly induced during in vitro granulocytic differentiation of human primary CD34(+) cells. Retinoic acid treatment of HL60 promyelocytic leukemia cells for 24 hr induced C/EBPepsilon mRNA levels by 4-fold, while prolonged treatment gradually reduced mRNA expression to pretreatment levels. Transient transfection experiments with expression vectors for two of the isoforms demonstrated that the 32.2-kDa protein is an activator of transcription of granulocyte colony-stimulating factor receptor promoter, while the 14.3-kDa protein is not. Thus, C/EBPepsilon is regulated in a complex fashion and may play a role in the regulation of genes involved in myeloid differentiation.

Mutations in the COL3A1 gene result in the Ehlers-Danlos syndrome type IV and alterations in the size and distribution of the major collagen fibrils of the dermis

Ehlers-Danlos syndrome type IV (EDS type IV) results from heterozygosity for mutations in the COL3A1 gene that encodes the chains of type III procollagen. By using light, transmission, and scanning electron microscopy, we examined skin biopsies from 22 individuals with EDS type IV in whom the COL3A1 mutations had been identified. The most striking changes in EDS type IV were correlated with point mutations that substituted a residue for a glycine near the carboxyl-terminal end of the triple-helical domain of pro alpha1(III). In three cases with the mutation G1012R, G1018V, or G1021E, cells in the dermis had extremely dilated rough endoplasmic reticulum (RER), the dermis was thin, and there was a reduced proportion of collagen although the proportion of elastic fibers appeared increased. In these tissues, collagen fibrils were small (65-80 nm) compared to normal (95-110 nm). Fibrils 80-90 nm in diameter and moderately dilated RER were found with mutations G769R, G373R, and G061E and with exon-skipping mutations of exons 34 and 45. With mutations G034R and G016C and exon-skipping mutations that deleted the sequences of exons 7, 8, 14, 18, 24, and 27, fibrils were more variable in size (85-120 nm). The composite collagen fibrils characteristic of EDS types I and II were not found in EDS type IV. These findings indicate that mutations in the COL3A1 gene have effects on secretion, fibrillogenesis, and skin architecture that reflect the position and nature of the mutation.

Measuring morbidity from asthma in children

AIMS

To develop new measures of asthma morbidity which would be applicable to children with asthma of all grades of severity.

METHODS

This study used a cross sectional sample of asthmatic children. Traditional asthma morbidity measures (admission to hospital, use of Emergency Room, general practitioner, after hours deputising service and ambulance) were compared with new measures (school attendance, teacher assessment, parental perception of morbidity and parents emotional response to child's asthma).

RESULTS

Data was obtained for 381 children with asthma. Children with poor school attendance were found in the severe group as judged by a composite score using traditional measures (r = 0.30, p < 0.0001). A new composite morbidity score based on two questions about parental perception of severity (how often has asthma prevented participation in activities and rating of severity of asthma in general over the last year) and two questions about parent emotional response to the child's asthma (how often has your child's asthma (a) made you feel frightened and (b) stopped family activities) was developed. This new measure of asthma morbidity was correlated with the composite score using traditional morbidity measures (r = 0.43, p < 0.0001) and with school attendance (r = 0.28, p < 0.0001).

CONCLUSION

These new morbidity measures are quick and easy to use, and provide an opportunity to measure asthma severity at the moderate to mild end of the severity spectrum. We recommend their use for both clinical assessment and research.

Sodium-driven, osmotically activated glycine betaine transport in Listeria monocytogenes membrane vesicles

Transport of the osmoprotectant and cryoprotectant glycine betaine was investigated in membrane vesicles of Listeria monocytogenes. Uptake-driving transmembrane potentials ranging from 111 to 122 mV within the pH range of 5.5 to 7.5 could be generated by the electron donor system ascorbate-phenazine methosulfate but not by the electron donor system ascorbate-N,N,N',N'-tetramethyl-p-phenylenediamine. Transport was dependent on both high concentrations of sodium ion and the presence of a hypertonic solute gradient. Arrhenius-type temperature activation was observed. Lineweaver-Burk plots indicated a Km of 4.4 microM for glycine betaine and a Vmax of 700 pmol/min x mg of protein. The Michaelis constant for NaCl depended on the solute used to maintain a constant hyperosmotic pressure, and the Km values were 200 and 75 mM when KCl and sucrose were employed, respectively. Transport was 65% lower in vesicles derived from cells grown under stress provided by KCI rather than NaCl and approximately 94% lower in vesicles derived from cells that were not grown under osmotic stress. This porter appears to be specific for glycine betaine, since neither proline, carnitine, nor choline inhibited uptake effectively. Kinetic studies using ionophores and artificial gradients indicate that glycine betaine is cotransported with sodium ion.

Role of osmolytes in adaptation of osmotically stressed and chill-stressed Listeria monocytogenes grown in liquid media and on processed meat surfaces

Listeria monocytogenes is a food-borne pathogen that is widely distributed in nature and is found in many kinds of fresh and processed foods. The pervasiveness of this organism is due, in part, to its ability to tolerate environments with elevated osmolarity and reduced temperatures. Previously, we showed that L. monocytogenes adapts to osmotic and chill stress by transporting the osmolyte glycine betaine from the environment and accumulating it intracellularly (R. Ko, L. T. Smith, and G. M. Smith, J. Bacteriol. 176:426-431, 1994). In the present study, the influence of various environmental conditions on the accumulation of glycine betaine and another osmolyte, carnitine, was investigated. Carnitine was shown to confer both chill and osmotic tolerance to the pathogen but was less effective than glycine betaine. The absolute amount of each osmolyte accumulated by the cell was dependent on the temperature, the osmolarity of the medium, and the phase of growth of the culture. L. monocytogenes also accumulated high levels of osmolytes when grown on a variety of processed meats at reduced temperatures. However, the contribution of carnitine to the total intracellular osmolyte concentration was much greater in samples grown on meat than in those grown in liquid media. While the amount of each osmolyte in meat was less than 1 nmol/mg (fresh weight), the overall levels of osmolytes in L. monocytogenes grown on meat were about the same as those in liquid samples, from about 200 to 1,000 nmol/mg of cell protein for each osmolyte. This finding suggests that the accumulation of osmolytes is as important in the survival of L. monocytogenes in meat as it is in liquid media.

Prevalence of hypopigmented macules in a healthy population

OBJECTIVE

Although hypopigmented macules are an important manifestation of tuberous sclerosis (TS), the probability of TS in healthy individuals who have hypopigmented macules is unknown. The purpose of this study was to establish the prevalence of hypopigmented macules among a cross section of the general white population.

STUDY DESIGN

The skin of 423 white individuals younger than 45 years of age was screened for hypopigmented macules with ambient incandescent and fluorescent light and a Wood lamp. Indirect ophthalmoscopy was performed in patients with unexplained hypopigmentation to screen for retinal manifestations of TS.

RESULTS

Twenty individuals (4.7%) had at least one hypopigmented macule. Of these, four had more than one macule. None had more than three. Two (8%) of the 25 hypopigmented macules were identified only with a Wood lamp. Indirect ophthalmoscopy was performed in 13 (65%) of these 20 individuals. None showed the retinal findings of TS.

CONCLUSIONS

The prevalence of hypopigmented macules in the general population has been underestimated. The presence of a few hypopigmented macules on the skin of an otherwise healthy individual without a family history of TS need not prompt an evaluation to rule out this disorder.

PU.1 (Spi-1) and C/EBP alpha regulate the granulocyte colony-stimulating factor receptor promoter in myeloid cells

Cytokines, important for lineage commitment and differentiation during hematopoiesis, exert their influence by binding specific receptors. Receptor expression is tightly regulated and examining the factors that govern their expression will allow better understanding of the events that determine lineage commitment. The granulocyte colony-stimulating factor (G-CSF) receptor is expressed exclusively in myeloid cells and the placenta. We show here that the G-CSF receptor transcription start site is identical in each of these tissues. A 1,391-bp fragment of the G-CSF receptor promoter is both active in myeloid cell lines and tissue specific. We have also found two regions that are important for G-CSF receptor promoter activity. One region, located at bp -49, contains a GCAAT site that specifically binds the C/EBP alpha transcription factor in myeloid nuclear extracts. Mutation of this site prevents C/EBP alpha binding and reduces promoter activity by 60%. The other functionally important region of the G-CSF receptor promoter is in the 5' untranslated region, at bp +36 and +43, where there are two sites for the ets family member PU.1. Mutation of these sites prevents PU.1 binding and reduces promoter activity by 75%. These results reinforce the importance of both PU.1 and C/EBP alpha in the expression of myeloid-specific genes and neutrophil development.

Selective deficits in visual perception and recognition in schizophrenia

OBJECTIVE

The purpose of this study was to evaluate the performance of patients with schizophrenia on tests of visual discrimination and recognition of different stimulus features.

METHOD

Thirteen medicated male schizophrenic patients and 13 normal comparison subjects were tested on four stimulus features: spatial frequency, pattern, location, and trajectory. Subjects had to make both discrimination and recognition judgments at three levels of stimulus disparity.

RESULTS

The responses of the patient group were slower and less accurate than those of the comparison group on both the discrimination and recognition tasks. The patients were less accurate than the comparison subjects in processing spatial features of the stimuli, particularly trajectory, but were unimpaired in processing form attributes (high spatial frequencies and patterns). When the results of pattern and trajectory tasks were matched against the accuracy performance of the comparison group, the patients were less accurate on trajectory than on pattern judgments and less accurate on recognition than on discrimination performance.

CONCLUSIONS

Schizophrenia may be accompanied by impaired visual spatial perception and representation. In schizophrenia, deficits in trajectory discrimination may reflect a disturbance of the dorsal pathway of the visual system, while disturbances of trajectory recognition performance may reflect a deficit in prefrontal systems involved in visual working memory operations.

Growth factor and growth factor receptor localization in the hair follicle bulge and associated tissue in human fetus

The bulge region of the hair follicle has been thought to contain follicular stem cells. The bulge in the human follicle is a collection of undifferentiated cells that is prominent only in the fetal period. Antibodies that recognize epidermal growth factor (EGF), transforming growth factor-alpha (TGF-alpha), EGF receptor, platelet-derived growth factor (PDGF) A and B chains, PDGF alpha and beta receptors, and the low-affinity nerve growth factor receptor (p75) were used to study the bulge and associated mesenchymal cells in this fetal period. Weak EGF and TGF-alpha immunoreactivities were seen in the bulge. Confocal laser scanning microscopic images revealed intracytoplasmic and intranuclear punctate patterns of immunoreactivities in the bulge cells labeled by anti-EGF and anti-TGF-alpha antibodies. All the bulge cells stained strongly for EGF receptor. Cells within the bulge were labeled both with PDGF A chain and with PDGF B chain, although the immunoreactivities were weak in the outermost layer of cells. The follicular sheath was strongly immunoreactive with antibodies against both PDGF alpha and beta receptors. p75 was expressed in mesenchymal cells around the hair follicle and in the lower portion of the bulge. These differential labeling patterns suggested that EGF, TGF-alpha, and nerve growth factor may be involved in regulation of the growth and differentiation of bulge cells and that PDGFs may have related functions in the interaction arising between the bulge and associated tissue during follicle morphogenesis.

Function of PU.1 (Spi-1), C/EBP, and AML1 in early myelopoiesis: regulation of multiple myeloid CSF receptor promoters

Our studies of the promoters of the myeloid CSF receptors (M, GM, and G) in cell lines have led to the findings that the promoters are small, and are all activated by the PU.1 and C/EBP proteins. To date, we have only found evidence for involvement of C/EBP alpha, although further experiments will be needed to exclude the role of C/EBP beta and C/EBP delta in receptor gene expression. These studies suggest a model of hematopoiesis (Fig. 2) in which the lineage commitment decisions of multipotential cells are made by the alternative patterns of expression of certain transcription factors, which then activate growth factor receptors which allow those cells to respond to the appropriate growth factor to proliferate and survive. For example, expression of GATA-1 activates its own expression, as well as that of the erythropoietin receptor, inducing these cells to be capable of responding to erythropoietin. Similarly, expression of PU.1 activates its own promoter, and turns on the three myeloid CSF receptors (M, GM, and G), pushing these cells along the pathway of myeloid differentiation. C/EBP proteins, particularly C/EBP alpha, are also critical for myeloid receptor promoter function, and may also act via autoregulatory mechanisms. Murine C/EBP alpha has a C/EBP binding site in its own promoter. Human C/EBP alpha autoregulates its own expression in adipocytes by activating the USF transcription factor. Myeloid genes expressed later during differentiation, such as CD11b, are also activated by PU.1, which is expressed at highest levels in mature myeloid cells, but not by C/EBP alpha, which is downregulated in a differentiated murine myeloid cell line. Consistent with this model are the findings that overexpression of PU.1 in erythroid cells blocks erythroid differentiation, leading to erythroleukemia, and overexpression of GATA-1 in a myeloid line blocks myeloid differentiation. While these findings have provided some framework for understanding myeloid gene regulation, there are a number of critical questions to be addressed in the near future: What is the pattern of expression of the C/EBP proteins during the course of myeloid differentiation and activation of human CD34+ cells? What is the effect of targeted disruption and other mutations of the C/EBP and AML1 proteins on myeloid development and receptor expression? What are the interactions among these three different types of factors (ets, basic region-zipper, and Runt domain proteins) to activate the promoters? What is the effect of translocations, mutations, and alterations in expression of these factors, particularly in different forms of AML?

ERP responses to target and nontarget visual stimuli in alcoholics from VA and community treatment programs

This study had three aims: 1) to cross-validate previously reported findings that sober alcoholics compared to nonalcoholic peers have reduced ERP P300 amplitudes to visual target stimuli at the Pz electrode; 2) to test the hypothesis that alcoholics from VA Hospital treatment programs will manifest more ERP indications of brain dysfunction than peer alcoholics from community treatment programs (paralleling our neuropsychological findings in these samples); and 3) to explore differences among the groups in ERP responses to the little-studied nontarget stimuli. Nineteen VA alcoholics, 32 community alcoholics, and 24 peer community controls were given a visual "oddball" stimulus task. The total group of alcoholics had significantly lower P300 amplitudes than controls for target stimuli at the Pz electrode but VA and community alcoholic subgroups did not differ. There were no latency differences between or among the groups. On the nontarget stimuli, alcoholics had significantly higher P100 and lower N100 amplitudes than the controls at all three scored electrodes (Fz, Cz, and Pz). We conclude that cross-validation of reduced P300 amplitudes at Pz in sober alcoholics was obtained but that differences in severity of brain dysfunction, at least as measured by neuropsychological test performance, cannot account for alcoholics' ERP changes relative to controls. Finally, our data suggest that ERP changes to nontarget visual stimuli should be investigated in addition to the more traditional ERP measures to target stimuli.

Expression of amphiregulin is regulated in cultured human keratinocytes and in developing fetal skin

Previous studies have indicated that amphiregulin is a major autocrine factor for human keratinocytes. To evaluate the possibilities that amphiregulin could function in fetal skin morphogenesis and contribute to the growth regulation of epidermis, immunostaining with a specific anti-amphiregulin monoclonal antibody was observed at different stages of fetal skin development, and the results were compared with neonatal and adult skin specimens and cultured neonatal keratinocytes. Immunoreactive amphiregulin was readily detected in the periderm and basal epidermal layers of embryonic epidermis but became gradually less detectable in the periderm concurrent with an increase in staining of the spinous layer as it developed during the fetal period. Basal and spinous keratinocyte expression of amphiregulin was predominantly cytoplasmic, but with punctate nuclear foci, and this pattern persisted into the neonatal period. At all developmental stages, epithelial and mesenchymal cells of the follicle were reactive, often in a nuclear pattern. Dermal mesenchymal cells were increasingly reactive in late fetal skin, but the staining decreased postnatally. In adult skin only randomly scattered nuclei of spinous keratinocytes and follicular structures such as the inner root sheath were stained. Examination by scanning laser confocal microscopy of cultured neonatal keratinocytes showed a nonrandom distribution of amphiregulin to the peripheral cytoplasm and plasma membranes at the outer perimeter of cell colonies, with much less reactivity of apposed keratinocyte membranes at interior sites. Nuclei were heterogeneously stained. Amphiregulin reactivity declined at higher cell densities. These data indicate that expression of amphiregulin is regulated in vitro and developmentally during cutaneous morphogenesis.

Prenatal diagnosis of Herlitz junctional epidermolysis bullosa by amniocentesis

Herlitz junctional epidermolysis bullosa (HJEB) is a severe blistering disorder which usually results in death during infancy. We have previously shown that the anchoring filament protein laminin-5 (kalinin/nicein), which mediates keratinocyte attachment and dermal-epidermal cohesion, is abnormally expressed in individuals with HJEB. Laminin-5 was detected by Western blot analysis in amniotic fluid from 44 consecutive normal second-trimester control pregnancies, but was undetectable in second-trimester amniotic fluid from four pregnancies with fetuses affected by HJEB. In one case of severe non-Herlitz JEB, laminin-5 was detected in both amniotic fluid and skin. In human amniotic fluid, the laminin-5 a3 subunit was processed to a major 165 kD species and a minor 145 kD species and the beta 2 subunit was partially processed to 105 kD. Although laminin-5 was covalently associated with laminin-6 (K-laminin) in amniotic membrane, no covalent interaction was detected in amniotic fluid. Laminin-5 from amniotic fluid strongly supported keratinocyte attachment. These results suggest that Western blot analysis of second-trimester amniotic fluid is useful in determining the prenatal diagnosis of HJEB and that laminin-5 may serve a physiologically important function in amniotic fluid.