Growing cells push back under pressure.

In both plants and animals, the interplay between mechanical force generation and mechanical sensing plays a stabilizing role in many developmental processes. Uyttewaal et al. now demonstrate that cells in the Arabidopsis shoot apical meristem respond to local mechanical stresses by reorienting their growth, thereby guiding morphogenesis. Notably, the mechanism underlying such guidance is amplification--not suppression--of growth-rate heterogeneity.

A novel microdeletion affecting the CETP gene raises HDL-associated cholesterol levels.

We describe a novel, inherited 16q13 microdeletion that removes cholesteryl ester transfer protein (CETP) and several nearby genes. The proband was originally referred for severe childhood-onset obesity and moderate developmental delay, but his fasting lipid profile revealed relatively high levels of high density lipoprotein cholesterol (HDL-C) and relatively low levels of low density lipoprotein cholesterol (LDL-C) for age, despite his obesity. Testing of first-degree relatives identified two other microdeletion carriers. Functional assays in affected individuals showed decreased CETP mRNA expression and enzymatic activity. This microdeletion may or may not be pathogenic for obesity and developmental delay, but based on the lipid profile, the functional studies, and the phenotype of other patients with loss-of-function mutations of CETP, we believe this microdeletion to be antipathogenic for cardiovascular disease.

Autosomal dominant PIK3R1 mutations cause SHORT syndrome.

PIK3R1 mutations cause syndromic insulin resistance with lipoatrophy. Thauvin-Robinet et al. (2013) The American Journal of Human Genetics 93: 141-149 SHORT syndrome with partial lipodystrophy due to impaired phosphatidylinositol 3 kinase signalling. Chudasama et al. (2013) The American Journal of Human Genetics 93: 150-157 Mutations in PIK3R1 cause SHORT syndrome. Dyment et al. (2013) The American Journal of Human Genetics 93: 158-166.

Exome sequencing identifies mutations in KIF14 as a novel cause of an autosomal recessive lethal fetal ciliopathy phenotype.

Gene discovery using massively parallel sequencing has focused on phenotypes diagnosed postnatally such as well-characterized syndromes or intellectual disability, but is rarely reported for fetal disorders. We used family-based whole-exome sequencing in order to identify causal variants for a recurrent pattern of an undescribed lethal fetal congenital anomaly syndrome. The clinical signs included intrauterine growth restriction (IUGR), severe microcephaly, renal cystic dysplasia/agenesis and complex brain and genitourinary malformations. The phenotype was compatible with a ciliopathy, but not diagnostic of any known condition. We hypothesized biallelic disruption of a gene leading to a defect related to the primary cilium. We identified novel autosomal recessive truncating mutations in KIF14 that segregated with the phenotype. Mice with autosomal recessive mutations in the same gene have recently been shown to have a strikingly similar phenotype. Genotype-phenotype correlations indicate that the function of KIF14 in cell division and cytokinesis can be linked to a role in primary cilia, supported by previous cellular and model organism studies of proteins that interact with KIF14. We describe the first human phenotype, a novel lethal ciliary disorder, associated with biallelic inactivating mutations in KIF14. KIF14 may also be considered a candidate gene for allelic viable ciliary and/or microcephaly phenotypes.

Susceptibility to multiple sclerosis is associated with the proximal immunoglobulin heavy chain variable region.

15 immunoglobulin heavy chain constant (CH) and variable region (VH) polymorphisms were selected to span the entire length of the heavy chain cluster. These polymorphisms were examined in 34 sib pairs concordant for multiple sclerosis (MS) and in 23 sporadic MS patients. Allele frequencies were calculated for the 2 MS patient groups and compared with those found in a control population from the same geographical location and of similar ethnic background. No significant association was found between MS and the 7 CH region polymorphisms examined. However, a significant correlation between the MS phenotype and a VH2 family polymorphism was observed in both MS patient populations (familial MS patients chi 2 = 8.16, P less than 0.005; sporadic MS patients chi 2 = 8.90, P less than 0.005). One allele of the VH2-5 gene segment was found to be over-represented in both MS groups. VH2-5 has recently been physically mapped close to the CH region, between 180 and 360 kb away. These results indicate that a locus near or within the CH-proximal VH region is associated with increased susceptibility to MS.

A systematic review of genetic syndromes with obesity.

Syndromic monogenic obesity typically follows Mendelian patterns of inheritance and involves the co-presentation of other characteristics, such as mental retardation, dysmorphic features and organ-specific abnormalities. Previous reviews on obesity have reported 20 to 30 syndromes but no systematic review has yet been conducted on syndromic obesity. We searched seven databases using terms such as 'obesity', 'syndrome' and 'gene' to conduct a systematic review of literature on syndromic obesity. Our literature search identified 13,719 references. After abstract and full-text review, 119 relevant papers were eligible, and 42 papers were identified through additional searches. Our analysis of these 161 papers found that 79 obesity syndromes have been reported in literature. Of the 79 syndromes, 19 have been fully genetically elucidated, 11 have been partially elucidated, 27 have been mapped to a chromosomal region and for the remaining 22, neither the gene(s) nor the chromosomal location(s) have yet been identified. Interestingly, 54.4% of the syndromes have not been assigned a name, whereas 13.9% have more than one name. We report on organizational inconsistencies (e.g. naming discrepancies and syndrome classification) and provide suggestions for improvements. Overall, this review illustrates the need for increased clinical and genetic research on syndromes with obesity.

NSD1 mutations generate a genome-wide DNA methylation signature.

Sotos syndrome (SS) represents an important human model system for the study of epigenetic regulation; it is an overgrowth/intellectual disability syndrome caused by mutations in a histone methyltransferase, NSD1. As layered epigenetic modifications are often interdependent, we propose that pathogenic NSD1 mutations have a genome-wide impact on the most stable epigenetic mark, DNA methylation (DNAm). By interrogating DNAm in SS patients, we identify a genome-wide, highly significant NSD1(+/-)-specific signature that differentiates pathogenic NSD1 mutations from controls, benign NSD1 variants and the clinically overlapping Weaver syndrome. Validation studies of independent cohorts of SS and controls assigned 100% of these samples correctly. This highly specific and sensitive NSD1(+/-) signature encompasses genes that function in cellular morphogenesis and neuronal differentiation, reflecting cardinal features of the SS phenotype. The identification of SS-specific genome-wide DNAm alterations will facilitate both the elucidation of the molecular pathophysiology of SS and the development of improved diagnostic testing.

Markers of epidermal differentiation expressed by rat keratinocytes cultured by a modified feeder layer technique.

A broad range of analytical methods has been used to investigate the expression of key differentiation markers in keratinocytes cultured by a modified feeder layer technique. Cultures were stratified and showed many of the features characteristic of epidermal differentiation in vivo including tonofilaments, desmosomes, loss of organelles and thickening of the plasma membrane to form the cornified envelope. Profilaggrin synthesis was detected by 32P-incorporation and the presence of filaggrin suggested that it was broken down by the normal route. Staining with the lectin from Ulex europeus revealed the presence of a fucose-containing cell-surface glycoprotein. Keratin synthesis was shown by 3H-leucine incorporation and keratins were analysed by two-dimensional gel electrophoresis in comparison with those from different levels of the epidermis. Quantitative and qualitative differences were found between in vivo and in vitro epidermal differentiation. In particular, cornified envelope numbers were low, in keeping with the observation by electron microscopy of only one layer of cells with this structure. The absence of a true stratum corneum in vitro was also indicated by the virtual absence of histidase activity and stratum corneum keratins. The keratin species present in vitro most closely resembled those of the basal cells of the epidermis, although even in this case differences were observed. The evidence as a whole is consistent with the belief that epidermal cells do synthesise in vitro many of the important proteins involved in differentiation, but that they nevertheless do not develop a true keratinised stratum corneum.

Fibronectin in cultured rat keratinocytes: distribution, synthesis, and relationship to cytoskeletal proteins.

The aim of this study was to investigate whether epidermal cells can synthesise fibronectin and whether the distribution of this glycoprotein is related to the adhesion and cytoskeletal organisation of these cells. The production of fibronectin by newborn rat epidermal cells was shown by indirect immunofluorescence staining of cultures grown in the absence of a feeder layer using an antiserum which had been cross-adsorbed with foetal calf serum proteins to remove antibodies which recognised serum fibronectin. The distribution of fibronectin in areas of cell-cell and cell-substratum contact, characteristically in the form of short radial stitches, was examined in more detail using immunoelectron microscopy with colloidal gold as marker. This showed the close proximity of fibronectin to the cell membrane, with the ventral surface and fine cellular processes showing the heaviest labelling, and also revealed evidence of a relationship between external fibronectin and internal structure in epidermal cells. Immunofluorescence showed that tonofilaments (keratin) and microtubules were present as fibrillar arrays but were not related to fibronectin distribution. Vimentin and desmin were absent. Actin was distributed as a circumferential bundle of filaments, with finer stands running radially to the edge. The latter were reminiscent of the radial fibronectin stitches and a spatial correspondence between fibronectin and actin was confirmed by double-label immunofluorescence which revealed many instances of overlap and colinearity of actin and fibronectin filaments. The ability of keratinocytes to produce fibronectin suggests that these cells can contribute to the formation of the basement membrane in skin. The localisation of fibronectin and its close association with actin also suggests that it is involved in keratinocyte adhesion and is related to the internal organisation of these cells.

Immune privilege in hair growth.

Immunostaining techniques were used to investigate the relationship between immune cells, proteoglycan, and class I MHC distribution in skin during the hair cycle in rats. The growth stage, anagen, was characterized by absence of class I MHC staining on most cells of the lower follicle and presence of chondroitin proteoglycan in the follicle sheath and dermal papilla. Immune cells were few in number and not associated with follicles. Dramatic changes were observed during regression in catagen; class I MHC was expressed on all follicle epithelium, large numbers of activated macrophages aggregated around the follicles, and the chondroitin proteoglycans disappeared from the follicle sheath and dermal papilla. During the resting stage, telogen, class I MHC remained on cells of the secondary germ, but macrophages and chondroitin proteoglycans were absent. These observations lead us to propose a hypothesis of immune privilege in hair growth.

Fibronectin distribution during the development of fetal rat skin.

Fibronectin distribution during fetal rat skin development has been studied immunocytochemically at the light and electron microscope level from 16 days of gestation to birth. The dermal-epidermal junction, the dermis, and connective tissue around developing muscle were shown by light microscopy to be heavily stained throughout this period. The development of hair follicles from about 18 days onward was not associated with any consistent change in fibronectin distribution. The heavy staining of the upper dermis was associated with a high density of mesenchymal cells, and immunoelectron microscopy revealed fibronectin on the surface of many of these cells and in association with the surrounding fine collagen fibrils. At the dermal-epidermal junction, both follicular and interfollicular, fibronectin was localized mainly in the plasma membrane and lamina lucida regions of the basement membrane, and there was also staining associated with the underlying fine collagen fibrils. These observations are further evidence for the proposed role of fibronectin as a mediator of the cell-matrix interactions which are of importance for tissue development and maintenance.

Distribution of proteoglycans during the hair growth cycle in human skin.

The involvement of proteoglycans in hair growth has been recognized through the observation of increased hair growth in diseases such as the mucopolysaccharidoses and pre-tibial myxedema, which involve an increase in skin proteoglycan content. In an attempt to understand this, we have examined the distribution of chondroitin 6 sulphate (C6S), unsulphated chondroitin (COS), dermatan sulphate (DS), and heparan sulphate proteoglycans (HSPG) in frozen tissue sections of normal scalp by immunostaining. Results show that during anagen, the thick connective tissue sheath around the follicle strains strongly for C6S, COS, and DS. COS is uniquely associated with this region and is not found beneath the epidermis or infundibular epithelium. HSPG is, however, localized in the basement membrane zone adjacent to the outer root sheath. In addition, all of these proteoglycans are localized in the dermal papilla. In mid-catagen, we observed significant loss of C6S and COS staining from both the dermal papilla and the connective tissue sheath, but no decrease in staining for HSPG. In late catagen, very little staining of C6S and COS was observed. In early anagen, we observed that C6S was again present in the connective tissue sheath and dermal papilla; however, COS staining appeared to be weaker and less closely associated with the follicle. HSPG staining was observed in early anagen in a pattern very similar to that found for other basement membrane components. Results for DS were not obtained for catagen or early anagen. These results provide further evidence that hair growth is associated with the presence of chondroitin proteoglycans in the follicle environment and that the cessation of growth is associated with their removal. Further studies are underway to characterize the relationship between hair growth and proteoglycans.

Rapid isolation in large numbers of intact, viable, individual hair follicles from skin: biochemical and ultrastructural characterization.

A rapid, novel method is described by which large numbers of intact, viable, individual hair follicles may be isolated from rat skin. Follicles are freed from the surrounding connective tissue by shearing, which is effected by repeated cutting with a loosely fitting pair of scissors, and collected individually under liquid using gentle aspiration. Ultrastructural analysis indicates that the follicles are sheared away from the surrounding dermis in the region of the connective tissue capsule which encircles the hair. The follicles appear viable by light and electron microscopy and, within 2 h of isolation, retain the capacity to incorporate [3H]thymidine into DNA and [35S]methionine into proteins as judged by autoradiography. A histologic comparison indicates that the structural integrity of follicles isolated by this new method is significantly superior to those plucked from the animal at the same time. The method affords the isolation of large numbers of hair follicles, without resort to enzyme treatments, suitable for biologic studies in the absence of other skin appendages and dermis.

Fibronectin distribution in epithelial and associated tissues of the rat.

Specific antiserum was used to investigate the distribution of the extracellular glycoprotein, fibronectin, in rat skin and tongue tissue by light and electron microscopy with immunofluorescence and immunoperoxidase techniques. We conclude that fibronectin is absent from stable, differentiated parts of tissues, such as the sebaceous glands or the matrix, medulla, cortex, and cuticles of the hair and the inner and outer root sheaths, or even in tissues in which there is some cell movement, such as the epidermis. It is, however, characteristic of sites at which cell division is occurring in contact with an extracellular scaffolding, such as basement membrane or loose connective tissue. Conspicuous examples were in the glassy membrane and connective tissue sheath associated with the follicular epithelium, the basement membrane underlying vascular endothelial cells, the connective tissues surrounding and investing nerve and muscle fibre bundles, and the dermal connective tissue where fibronectin was often associated closely with collagen fibres. At the basement membrane of the dermal/epidermal junction, fibronectin occurred at the plasma membrane of the basal cells and in the lamina lucida area. There was no correlation with specific areas of cell-substrate adhesion, such as the hemidesmosomes. The endoplasmic reticulum of fibroblasts stained strongly suggesting that these cells represent a major site of synthesis.

Interactions of C12 surfactants with the skin: studies on enzyme release and percutaneous absorption in vitro.

Using an in vitro penetration cell, it has been shown that enzymes (acid phosphatase, lactate dehydrogenase and N-acetylglucosaminidase) are released from rat-skin slices in response to contact with two irritant C12 surfactants, sodium laurate and sodium lauryl sulphate, but not with the non-irritant sodium lauroyl isethionate. About 3-5 hr contact of the stratum corneum with surfactant and a long incubation time (24 hr) were required for enzyme release. Adsorption and penetration of the two effective surfactants was also studied and the results for sodium lauryl sulphate suggested a relationship between enzyme release and adsorption of surfactant. However, no such simple relationship was observed for sodium laurate, emphasizing the complex nature of surfactant interactions with the skin.

Interactions of C12 surfactants with the skin: changes in enzymes and visible and histological features of rat skin treated with sodium lauryl sulphate.

Rat skin was treated with 35 mM-sodium lauryl sulphate (SLS) and samples were taken after one, three or five treatments, or 24 hr after the fifth treatment for measurement of enzyme release and epidermal enzyme levels. Release of acid phosphatase (AP) and lactate dehydrogenase (LDH) was significantly higher than in controls after five treatments with SLS, and epidermal levels of AP, LDH and N-acetylglucosaminidase were also higher than in controls in skin taken 24 hr after the fifth treatment. The relationship of these changes to the irritant response, assessed visually and histologically, was investigated in two out of three experiments. Although the timing of the irritant response was variable, enzyme release accompanied the development of erythema and oedema in each case, and extensive enzyme release was associated histologically with epidermal oedema and an increase in dermal leucocytes. The increase in epidermal enzyme activities also followed the development of the reaction to SLS, and it seemed to be related to epidermal thickening.

The effect and mode of action of zinc pyrithione on cell growth. II. In vivo studies.

The effect of topical application of the anti-dandruff agent zinc pyrithione (ZnPTO) on epidermal DNA synthesis in normal and hexadecane-stimulated rat skin was investigated. Autoradiography was used to determine the percentage of epidermal cells labelled with [3H]thymidine (labelling index). ZnPTO at 1% in shampoo base caused a slight increase in the labelling index in normal skin, similar to the effect of the shampoo base alone. No effect of 1% ZnPTO as an aqueous dispersion was observed. ZnPTO at 1% in shampoo base did not reduce the large increase in labelling index produced by hexadecane, nor did shampoo base alone or 1% ZnPTO in water. The shampoo base with or without 1% ZnPTO had only a very slight effect on the histopathology of normal and hexadecane-treated skin, and 1% ZnPTO in water had no effect. It is concluded that the in vitro potential of ZnPTO to cause growth inhibition is not achieved in vivo, presumably because of low percutaneous absorption. This evidence does not support a cytostatic mode of action in clearing dandruff.

The effect and mode of action of zinc pyrithione on cell growth. I. In vitro studies.

The effects of zinc pyrithione (ZnPTO) were studied in a series of in vitro tests to determine whether its mode of action is primarily cytostatic or cytotoxic. Sodium pyrithione (NaPTO) was also studied, to check that pyrithione was the active moiety, and the known cytostatic chemical hydroxyurea was included for comparison. ZnPTO had a reversible inhibitory effect on the growth of BHK 21 cells at 0.1 microgram/ml, but had a rapid, irreversible inhibitory effect at 1 microgram/ml associated with cell rounding and detachment. NaPTO produced a similar effect but hydroxyurea produced an essentially reversible inhibition even at a dose well above that producing complete inhibition. ZnPTO and NaPTO both caused contraction, rounding and blebbing of BHK 21 cells in perfusion-chamber tests, at higher levels (1 and 10 micrograms/ml) than required for growth inhibition, but only 10 micrograms ZnPTO/ml caused lactate dehydrogenase (LDH) release. Hydroxyurea had no effects in these tests. ZnPTO and NaPTO also reduced the survival of Chinese hamster V79 cells sharply over a narrow dose range (0.01-0.03 microgram/ml), but the effect of hydroxyurea was not as sharp and occurred at much higher doses. All three showed elements of cytostasis and cytotoxicity as demonstrated by analysis of the relationship between survival and colony area. Of the three, only ZnPTO (at greater than or equal to 5 micrograms/ml) caused significant LDH release from the cells, though both ZnPTO and NaPTO (at 0.1-1 microgram/ml) inhibited cell growth as indicated by total LDH values. In studies with rat peritoneal mast cells, ZnPTO and NaPTO (at 10 ng/ml) both suppressed histamine release induced by 48/80 or Ca ionophore A23187, though neither caused histamine release directly. The combined results of these tests show that ZnPTO is primarily cytotoxic, rather than cytostatic.

Homosexuality, class and the church in nineteenth century England: two case studies.

This article seeks to reconstruct and contrast two episodes in the nineteenth century Church. Both involved churchmen, Bishop Percy Jocelyn and Dean Charles Vaughan, in homosexual incidents. The second episode, that of Dean Vaughan, has been reconstructed for the first time using the Broadlands Manuscripts of Lord Palmerston. The most interesting aspect of these events is the response of the "establishment" to homosexuality. There seems little doubt that attitudes of the "establishment" were determined largely by class. The "establishment" would not officially condone homosexual behaviour, but in both cases (to varying degrees) it seems to have acted toward these men with latitude. One was able to evade justice, the other denied a mitre but otherwise allowed advancement in the Church. Both incidents provide evidence that persecution of homosexuals was something confined to the lower orders; and that the discreet middle class or aristocratic homosexual could rely on his class for protection. Perhaps integral to this tolerance was a Victorian taste for self-denial. The homosexual who treated his sexuality as a curse and a source of tragedy was more likely to attract the tolerance of his peers than the homosexual who acknowledged his sexuality to the full.