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Biomedical subjects

H Winter

Publications and source records attributed to H Winter.

At least 73 records · Page 4Linked to original sources
PubMed1998

A variable monilethrix phenotype associated with a novel mutation, Glu402Lys, in the helix termination motif of the type II hair keratin hHb1.

Monilethrix is a rare human hair disorder with autosomal dominant transmission that can be caused by mutations in hair keratins. Up until now, pathogenic mutations in the type II hair cortex keratins hHb6 and hHb1 were restricted to a highly conserved glutamic acid residue Glu413 (Glu117 of the 2B subdomains) in the EIATYRRLLEGEE helix termination motif of the two keratins. The critical glutamic acid residue was substituted either by a lysine or, less frequently, by an aspartic acid residue. Here we report a novel mutation in a French monilethrix family, which again consists of a lysine substitution of another highly conserved glutamic acid residue, Glu402 (Glu106 of the 2B subdomain), in the EIATYRRLLEGEE motif of hHb1. Family members bearing the hHb1 Glu402Lys mutation exhibit a particularly variable disease phenotype. The pedigree comprises two infant members, one with pronounced dystrophic alopecia, follicular keratosis, and clear-cut moniliform hair, and one with no hair loss at all and moniliform hair detectable only by electron microscopy, as well as an adult individual without any clinically or electron microscopically detectable symptoms, but with clear historical proof of the disease.

Adult↗
PubMed1998

A novel human type II cytokeratin, K6hf, specifically expressed in the companion layer of the hair follicle.

In an attempt to identify new members of the human type II hair keratin family by means of 3'- and 5'-RACE methods and cDNA from anagen hair follicles, we detected a sequence that encoded a hitherto unknown type II cytokeratin. The novel cytokeratin comprises 251 amino acids and exhibits the highest sequence homology with K5. Comparative one- and two-dimensional western blots of keratins from anagen hair bulbs, containing or not containing the outer and inner root sheaths (ORS/IRS), and from footsole epidermis with an antibody against the new cytokeratin, revealed its comigration with K6 and its expression in the ORS/IRS complex. We have therefore named the new cytokeratin K6hf, to distinguish it from the various K6 isoforms and to indicate its expression in the hair follicle. Both in situ hybridization with a K6hf-specific cRNA probe and indirect immunofluorescence with the K6hf antibody showed that K6hf is exclusively expressed in the so-called "companion layer" of the hair follicle, a single layered band of flat and vertically oriented cells between the cuboidal ORS cells and the IRS that stretches from the lowermost bulb region to the isthmus of the follicle. Concomitant K17 and K16 expression studies showed that besides suprabasal ORS cells, these cytokeratins are sequentially expressed subsequent to K6hf in companion cells above the hair bulb. Our study confirms the view of a vertically oriented companion layer differentiation. The clearly delayed K17 and K16 expression relative to that of K6hf in companion cells most probably excludes these keratins as possible type I partners of K6hf and suggests the existence of a still unknown type I partner of its own. Thus, not only morphologically but also biochemically, the companion layer is different from the ORS and can therefore be regarded as an independent histologic compartment of the hair follicle.

Amino Acid Sequence↗
PubMed1998

Reinnervation of split skin grafts in humans: comparison of two different methods of operation.

Studies on the reinnervation of split skin grafts have produced contradictory results. As the difference in sensitivity may be caused by the method of grafting, sensory reinnervation was studied in split skin grafted by two different methods. Thirty-nine patients given split skin grafts after the excision of malignant melanoma took part in the study. In 17 patients, split skin was grafted on to the intact muscle fascia. In another 22 patients the skin was grafted directly on to the muscle after the fascia had been removed. In all patients, sensitivity (to touch, heat/cold, and pain) was tested on the grafts and the skin from the opposite side. Sensory functions on grafted skin were generally reduced. Patients with split skin grafted on to the intact muscle fascia had better reinnervation than the ones in whom the fascia had been removed. However, individual patients from both groups showed surprisingly good reinnervation of transplanted skin. The reasons for this finding are not clear, but it is quite possible that the characteristics of the grafted skin have some influence on the reinnervation.

Adult↗
PubMed1997

Membrane association of sucrose synthase: changes during the graviresponse and possible control by protein phosphorylation.

Sucrose synthase (SuSy) plays an important role in sucrose degradation and occurs both as a soluble and as a membrane-associated enzyme in higher plants. We show that membrane association can vary in vivo in response to gravistimulation, apparently involving SuSy dephosphorylation, and is a reversible process in vitro. Phosphorylation of SuSy has little effect on its activity but decreases its surface hydrophobicity as reported with the fluorescent probe bis-ANS. We postulate that phosphorylation of SuSy (and perhaps other membrane proteins) is involved in the release of the membrane-bound enzyme in part as a result of decreased surface hydrophobicity.

Adenosine Triphosphate↗
PubMed1997

A splice site mutation in the gene of the human type I hair keratin hHa1 results in the expression of a tailless keratin isoform.

In this study, we have elucidated the molecular mechanisms underlying the expression of an acidic 41-kDa protein inherited as an autosomal dominant trait of the hair keratin pattern of about 5% of the human population. We show that this protein is a size variant of the large type I hair cortex keratin hHa1 due to a genetic polymorphism in the hHa1 gene. We detected a G-A substitution in the 5' splice site of intron 6 of the hHa1 gene, which segregates with the 41-kDa protein phenotype in two pedigrees and is responsible for the formation of an abnormally spliced hHa1 mRNA species. The use of an alternative 5' splice site leads to the retention of 41 nucleotides of the initial intron 6 sequences in the mature transcript. The open reading frame of the aberrant mRNA creates a premature stop codon immediately downstream of the mutation site. The resulting hHa1 protein variant, hHa1-t, is about 6-kDa smaller than the 47-kDa hHa1 hair keratin and lacks the complete nonhelical tail domain. We show that the tailless hHa1-t is functional, since both recombinant hHa1 and hHa1-t form identical keratin intermediate filaments when assembled in vitro with a type II hair keratin partner. This finding confirms the view of a noninvolvement of the keratin tail domain in filament assembly and explains the lack of a pathological hair phenotype in hHa1-t positive individuals.

Base Sequence↗
PubMed1997

Phosphodiester amidates of unsaturated nucleoside analogues: synthesis and anti-HIV activity.

The effect of introduction of a lipophilic phosphodiester amidate moiety on the HIV activity of inactive unsaturated nucleoside analogues was investigated. Phosphodiester alaninates 5a, 5b, and 6 derived from unsaturated nucleoside analogues 3b, 3c, and 4a were synthesized and investigated as inhibitors of cytopathic effect and replication of HIV-1 in ATH-8 cells. Compound 5a is an inhibitor of HIV-1 whereas analogue 6 is inactive with cytotoxicity appearing above 10 microM and 5b is both inactive and nontoxic. Alkaline or enzymic hydrolysis of 5a gave phosphomonoester alaninate 14, a putative product of intracellular metabolism. Compound 14 as well as adenallene derivative 15c were devoid of anti-HIV activity, and they also failed to inhibit HIV reverse transcriptase. A new regioselective method for preparation of (Z)-4-(benzoyloxy)-1-hydroxy-2-butene, 7, a key intermediate for the synthesis of unsaturated nucleoside analogues of cis configuration such as 3a, 3b, and 3c, is also described.

Animals↗
PubMed1997

Retinoic acid signaling cascade in differentiating murine epidermal keratinocytes: alterations in papilloma- and carcinoma-derived cell lines.

The retinoic acid (RA) signaling pathway was investigated by transient transfection of a chloramphenicol acetyltransferase (CAT) reporter gene construct containing the RA response element (RARE) of the murine (m) RARbeta2 gene into murine primary epidermal keratinocytes (PEK), papilloma-derived SP1 cells, and carcinoma-derived 3P2 cells. Murine PEK transfected in a low-Ca2+ medium (0.05 mM Ca2+) exhibited a strong transactivation of the CATgene after exposure of the cells to 0.1 microM RA. Transactivation of the CATgene could, however, also be achieved by shifting RAREbeta2-transfected low-Ca2+ PEK to high-Ca2+ conditions (0.15-1.2 mM Ca2+). Concomitantly, the Ca2+ raise also led to the induction of both cellular retinol (ROL)-binding protein I (CRBPI) and cellular RA-binding protein II (CRABPII), whereas expression of cellular RA-binding protein I (CRABPI) was not observed. Moreover, induction of in vitro differentiation also activated the ROL-->RA converting enzyme system in PEK. These findings suggest the following sequence of events involved in the high Ca2+-mediated activation of RAREbeta2. First, high Ca2+ induces the synthesis of mCRBPI, which binds ROL released from retinyl ester stores and makes it accessible to the ROL-RA converting enzyme system. Enzymatically generated RA is taken over by mCRABPII and transported to the nucleus, where it acts as ligand for nuclear receptors, which complex with RAREbeta2 to activate the reporter gene. This hypothetical cascade of RA signaling was supported by our findings that inhibition of the ROL-->RA converting enzyme system by citral abolished the Ca2+-mediated transactivation of the CAT gene in a nontoxic manner. Studies in transformed murine cell lines revealed that Ca2+-induced activation of RAREbeta2 was essentially maintained in papilloma-derived SP1 cells, although all parameters of the Ca2+-dependent RAREbeta2 activation cascade were induced to a much lower extent. In contrast, strong RAREbeta2 activity was already observed in low-Ca2+ carcinoma-derived 3P2 cells. Low-Ca2+ 3P2 cells also expressed high levels of both mCRBPI and mCRABPII and possessed a highly active ROL-->RA converting enzyme system. Again, inhibition of the enzyme by citral abolished RAREbeta2 activity in low-Ca2+ 3P2 cells. Our data show that Ca2+-induced differentiation in cultured murine PEK entails a series of events that ultimately lead to the activation of RARE-containing genes. These properties are maintained in transformed epidermal keratinocytes. However, with increasing malignant potential of the cells, the respective signaling pathway becomes independent from a differentiation stimulus and leads to constitutive activation of RARE-controlled genes.

Animals↗
PubMed1997

A new mutation in the type II hair cortex keratin hHb1 involved in the inherited hair disorder monilethrix.

Monilethrix is a rare dominant hair disease characterized by beaded or moniliform hair which results from the periodic thinning of the hair shaft and shows a high propensity to excess weathering and fracturing. Several cases of monilethrix have been linked to the type II keratin gene cluster on chromosome 12q13 and causative heterozygous mutations of a highly conserved glutamic acid residue (Glu 410 Lys and Glu 410 Asp) in the helix termination motif of the type II hair keratin hHb6 have recently been identified in monilethrix patients of two unrelated families. In the present study, we have investigated two further unrelated monilethrix families as well as a single case. Affected members of one family and the single patient exhibited the prevalent hHb6 Glu 410 Lys mutation. In the second family, we identified in affected individuals a lysine substitution of the corresponding glutamic acid residue, Glu 403, in the type II hair keratin hHb1, suggesting that this site represents a mutational hotspot in these highly related type II hair keratins. Both hHb1 and hHb6 are largely coexpressed in cortical trichocytes of the hair shaft. This indicates that monilethrix is a disease of the hair cortex.

Amino Acid Sequence↗
PubMed1997

Mutations in the hair cortex keratin hHb6 cause the inherited hair disease monilethrix.

Pathogenic mutations in a large number of human epithelial keratins have been well characterized. However, analogous mutations in the hard alpha-keratins of hair and nail have not yet been described. Monilethrix is a rare autosomal dominant hair defect with variable expression. Hairs from affected individuals show a beaded structure of alternating elliptical nodes and constrictions (internodes). These internodes exhibit a high prospensity to weathering and fracture. Strong evidence that trichocyte keratin defects might underlie this hair disorder was provided by genetic linkage analyses that mapped this disease to the type-II keratin gene cluster on 12q13. All affected individuals from a four-generation British family with monilethrix, previously linked to the type-II keratin gene cluster, as well as three unrelated single monilethrix patients, exhibited a heterozygous point mutation in the gene for type-II hair cortex keratin hHb6, leading to lysine substitution of a highly conserved glutamic acid residue in the helix termination motif (Glu 410 Lys). In a three-generation French family with monilethrix of a milder and variable phenotype, we detected another heterozygous point mutation in the same glutamic acid codon of hHb6, which resulted in a conservative aspartic acid substitution (Glu 410 Asp). These mutations provide the first direct evidence for involvement of hair keratins in hair disease.

Adolescent↗
PubMed1997

Sequences and differential expression of three novel human type-II hair keratins.

As part of a program designed to characterize human hair keratin genes and their expression, we present the cDNA sequences and deduced amino acid sequences of three type-II hair keratins hHb3, hHb5, and hHb6, which by virtue of their amino acid homologies are the orthologs of the previously described sheep wool keratins, K2.10, K2.12, and K.211 [29]. Amino acid sequences comparisons of these keratins, including the previously characterized human K2.9 ortholog hHb1, show extreme conservation not only in the alpha-helices but also in the aminoterminal and proximal carboxyterminal domains. They also demonstrate higher sequence relationships between hHb1, hHb3, and hHb6 as compared to hHb5, which exhibits chain-specific sequences in both the head and tail domains. In situ hybridization studies using specific 3'-probes for the four type-II hair keratins reveal sequential patterns of gene expression in human anagen follicles. Remarkably the onset of hHb5 mRNA synthesis occurs immediately above a small population of matrix cells at the base of the hair bulb and the trichocytes lining the dermal papilla. hHb5 mRNA synthesis extends upward through the matrix and ends in the lower part of the cortex of the hair shaft. In contrast, both hHb1 and hHb3 mRNA synthesis begins simultaneously in the cortex 10-15 cell layers above the apex of the dermal papilla, thus partially overlapping that of hHb5 but continuing to a point well beyond hHb5 in the upper cortex. Synthesis of hHb6 mRNA starts slightly higher than either hHb1 or hHb3 mRNA and proceeds much farther up into the keratogenous zone of the hair shaft. Our study demonstrates that the differentiation of human hair in terms of hair keratin expression begins much earlier than previously assumed, i.e. in lower matrix cells of the hair bulb. This early phase of hair differentiation is followed by a late cortical phase of terminal differentiation which comprises at least three type-II hair keratins in the zone of elongation and the keratogenous zone of the hair shaft.

Amino Acid Sequence↗
PubMed1996

Phosphodiester amidates of allenic nucleoside analogues: anti-HIV activity and possible mechanism of action.

Lipophilic phosphodiester amidates 2a, 2b, 4a, 4b, and 6 derived from anti-HIV agent adenallene 1a, 3a, inactive hypoxallene 1b, 3b, and 9-(4-hydroxy-2-butyn-1-yl)adenine (5) were synthesized and studied as inhibitors of HIV-1 in ATH8 cell system. All phosphodiester amidates were more biologically active than their parent nonphosphorylated compounds. Analogues 2a and 4a derived from (+/-)-adenallene 1a and (R)-enantiomer 3a are effective anti-HIV agents with EC50 approximately 0.88 and 0.21 microM, respectively. Both analogues are 16 and 28 times more effective than parent compounds 1a and 3a, respectively. Some anti-HIV activity of hypoxallene derivatives 2b and 4b was noted in the range of 0.1-10 microM but the dose-response relationship was poor. Phosphodiester amidate analogue 6 also exhibited anti-HIV activity in the range of 0.1-100 microM, but this effect was accompanied by cytotoxicity. Hydrolytic studies performed at pH 9.8 and with pig liver esterase at pH 7.4 have shown that analogue 2a gives adenallene 4'-phosphoralaninate (10a) as the major product. These results can be interpreted in terms of initial hydrolysis of phosphodiester amidates 2a, 2b, 4a, 4b, and 6 catalyzed by intracellular esterase(s) to give stable phosphomonoester amidate intermediates with a free carboxyl group. The results obtained with hypoxallene phosphoramidates 2b and 4b indicate that the aminosuccinate-fumarate enzyme system responsible for activation of AIDS drug ddIno (didanosine, Videx) can also, albeit less efficiently, activate hypoxallene 4'-phosphate (9b) and the respective (R)-enantiomer released inside the HIV-infected cells.

Adenosine Monophosphate↗
PubMed1996

Gastrointestinal and nutritional problems in children with immunodeficiency and AIDS.

Immunodeficient children pose a challenge to clinicians because of the interrelationship between infectious disease, metabolism, gastrointestinal tract function, psychosocial problems, and immune function. The interplay between these factors is not always clear, and frequently the best course of therapy is obscured because of an inability to determine which factors have the greatest impact on child health. To optimize therapeutic intervention, a multidisciplinary health care team must be involved with the management of children and their families.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Historical perspectives on the evolution in understanding the importance of nutritional care in pediatric HIV infection.

Women, perinatally-infected infants, and sexually exposed and exploited youths and adolescents have become a major focus of the worldwide HIV/AIDS pandemic. Increased perinatal screening, improvement in early infant diagnosis, and the benefits of primary HIV therapies have increased the numbers identified and longevity of infants and children living with HIV. This increase in survival is associated with HIV/AIDS becoming a chronic multiorgan system disease that requires a multidiscipline comprehensive care approach. The combination of poor oral intake, increased loss, and increased metabolic needs of long-term surviving HIV-infected children are obstacles to both survival and quality of life. HIV-infected children and their families need supportive care services including nutritional as well as primary therapy. Clinical guidelines for effective nutrition interventions must be developed to prevent and treat failure to thrive and wasting syndrome. Gains in survival duration must be linked to enhanced quality of life through supportive care, including comprehensive nutritional services that have their efficacy documented by appropriate clinical trials.

Adolescent↗
PubMed1996

Gastrointestinal tract function and malnutrition in HIV-infected children.

Poor growth and/or weight gain was identified in the initial reports of children with AIDS (Oleske et al. 1983, Rubinstein et al. 1983). However, in the past 12 years little progress has been made to understand the mechanisms for these observations. Data from the NIAID/NICHD multicenter Women and Infants Transmission Study (WITS) demonstrated that a decline in weight occurred in the first four months of life followed by decreased linear growth (Rich et al. 1993). In older children weight and height seem to decline in parallel (McKinney et al. 1993), but loss of lean body mass may occur prior to a decline in weight (Miller et al. 1993). Adequate caloric intake can improve weight gain, but has little effect on height velocity and lean body mass (Henderson et al. 1994, Miller et al. 1992). Long-term survivors with HIV infection are shorter than anticipated, and these changes cannot be explained solely by inadequate nutrition or by endocrine abnormalities. The immune system, gastrointestinal tract function, malnutrition, and chronic or recurrent infection interact and contribute to the nutritional deficiencies and problems with growth observed in the HIV-infected child.

Child↗