Wound dressing with sustained anti-microbial capability

Amphiphilic poly(ether ester amide) (PEEA) multiblock copolymers were synthesized by polycondensation in the melt from hydrophilic poly(ethylene glycol) (PEG), 1,4-dihydroxybutane and short bisester-bisamide blocks. These amide blocks were prepared by reaction of 1,4-diaminobutane with dimethyl adipate in the melt. A range of multiblock copolymers were prepared, with PEG contents varying from 23-66 wt %. The intrinsic viscosity of the PEEA polymers varied from 0.58-0.78. Differential scanning calorimetry showed melting transitions for the PEG blocks and for the amide-ester blocks, suggesting a phase separated structure. Both the melting temperature and the crystallinity of the hard amide-ester segments decreased with increasing PEG content of the polymers. The equilibrium swelling ratio in phosphate buffered saline (PBS) increased with increasing amount of PEG in the polymers and varied from 1.7 to 3.7, whereas the polymer that contained 66 wt % PEG was soluble in PBS. During incubation of PEEA films in PBS, weight loss and a continuous decrease in the resulting inherent polymer viscosity was observed. The rate of degradation increased with increasing PEG content. The composition of the remaining matrices did not change during degradation. A preliminary investigation of the protein release characteristics of these PEEA copolymers showed that release of the model protein lysozyme was proportional to the square root of time. The release rate was found to increase with increasing degree of swelling of the polymers.     

Human papillomavirus in oesophageal squamous cell carcinoma.

Thirty seven cases of oesophageal squamous cell carcinoma were studied by applying DNA slot blot analysis and in situ hybridisation using type specific probes for HPV 6, 11, 16 and 18. Cases of condyloma accuminata, cervical carcinoma, and laryngeal papilloma were used as controls. Blocks including areas of invasive carcinoma, intraepithelial neoplasia, and normal epithelium were studied in each case. No HPV genome was detectable in any of the oesophageal cases. It is concluded that these types of HPV do not have an association with oesophageal squamous cell carcinoma.     

Molecular studies of trophoblast HLA-G: polymorphism, isoforms, imprinting and expression in preimplantation embryo

There is considerable interest in human HLA-G arising from the observation that it is expressed selectively on the surface of extravillous trophoblast, the fetal cell population directly in contact with the mother. We investigated several aspects of the molecular biology of this unusual molecule. Limited polymorphism at the nucleotide level, and even more restricted variation at the amino acid level, was found in our Caucasian population. A further unusual aspect of HLA-G is the occurrence of alternatively spliced mRNAs. Spliced messages that could give rise to either membrane-bound or soluble proteins have been reported and six of these alternative forms were detected in all first trimester and term placentae, highly purified villous and extravillous trophoblast and the cell lines, JEG-3 and 221-G. An additional novel splice variant involving loss of part of the 3'-untranslated region was observed with two alleles. Using a sensitive RNase protection assay higher levels of the membrane-bound RNAs as compared to the soluble forms were detected in first trimester and term placentae as well as in JEG-3. Contrary to previous findings our term samples taken from the maternal aspect showed higher levels of both mRNA species when compared to first trimester placenta. The question of imprinting was addressed through the detection of heterozygotes both in placental tissue and, more tellingly, in the purified trophoblast cells. There was no evidence of imprinting. In addition we did not find mRNA for HLA-G in human two to eight-cell embryos or in blastocyst or in sperm samples.     

Human trophoblast adhesion to matrix proteins: inhibition and signal transduction

At the time of implantation, the extracellular matrix proteinslaminin and fibronectin are abundant in the decidua and aredistributed pericellularly around each individual stromal cell.First trimester human trophoblast expresses both laminin andfibronectin receptors, specifically the ₁ß_{1 5}ß₁₆ß₁ and ₆ß₄ integrin heterodimers. In thisstudy we have demonstrated that in-vitro adhesion of first trimesterhuman trophoblast to purified extracellular matrix proteinsand to purified decidual stromal cell monolayers can be inhibitedby monoclonal antibodies directed against appropriate integrinsubunits and by synthetic peptides containing an arginine-glycine-asparticacid sequence. Monoclonal antibodies (mAbs) to the ₅ and ß₁integrin subunits and a synthetic peptide significantly inhibitedadhesion to fibronectin. Binding of trophoblast to laminin wasblocked with mAbs to the ₆ and ß₁ but not ₁ and ß₄integrinsubunits. Similarly, integrin-mediated adhesion to monolayersof decidual stromal cells could be blocked with mAbs to the₅, ₆, ß₆ and ß₄ integrin subunits. Integrin-mediatedsignal transduction in normal and malignant trophoblast wasinvestigated by Western blotting. A 115 kDa protein was themajor tyrosine phosphorylated protein detected in trophoblastafter binding to laminin or fibronectin. The profile of tyrosinephosphorylated proteins differed for malignant trophoblast. integrins/matrix/signal transduction/trophoblast     

Paternal monoallelic expression of PEG3 in the human placenta

Genomic imprinting is the phenomenon whereby mono-allelic expression of certain genes occurs depending on their parental origin. The observation that imprinting only occurs in placental mammals has led to the suggestion that it may play a role in this form of reproduction. In the present study we have investigated the pattern of expression of the human PEG3 gene in the early to term placenta, as well as the uterus and ovary, using RT-PCR, northern blot and in situ hybridization. A comparison is made with the expression of Peg3 in the mouse by histochemical staining in betageo knock out mice. We have demonstrated high levels of PEG3 in the human placenta and have localized the signal to the layer of villous cytotrophoblast cells. In contrast, the pattern of expression of Peg3 in the mouse placenta is less restricted, the message being present in all trophoblast populations. Thus, expression of PEG3/Peg3 in the human and mouse placenta is not directly comparable. We have also detected PEG3 message in the ovarian stroma. We have sequenced the human PEG3 gene from exon 3 to exon 9. By utilizing a polymorphism detected in exon 9, we have established that only the paternal allele is expressed in human placenta. Human PEG3 is therefore maternally imprinted as in mouse.     

The influence of the maternal uterine immune response on placentation in human subjects.

The immunological relationship between the mammalian fetus and its mother during pregnancy has been considered similar to that between a transplanted allograft and its recipient ever since Medawar (1953) first proposed the concept of the 'fetus as an allograft' in the early 1950s. Based on this analogy, it has been assumed that implantation of the fetal placenta in the uterus would be controlled similarly by a maternal immune response mediated by T-cells recognizing paternally-derived alloantigens expressed by the placenta. Surprisingly, recent evidence suggests that implantation might involve predominantly a novel allogeneic recognition system based on natural killer cells rather than T-cells (Loke & King, 1995). The cellular and molecular basis of this local immune interaction between the fetal placenta and maternal uterus is now the focus of intense research interest. Since aberrant implantation can cause a variety of clinical problems, including miscarriage, intrauterine growth retardation and pre-eclampsia, an understanding of the immunological mechanism by which this process is controlled could lead to the development of regimens to improve fetal growth and development.     

Vitiligo in children and adolescents: association with thyroid dysfunction

Background The clinical characteristics of vitiligo in children and adolescents with an emphasis on thyroid dysfunction have only been reported in a few studies. Objective The purpose of this study was to examine the characteristics of children and adolescents with vitiligo and compare the incidence of thyroid dysfunction between them and controls without vitiligo at the same age. Methods A retrospective analysis of 324 Korean children and adolescents with vitiligo was performed. The results of thyroid function screening tests in them (n = 254) were compared with controls (n = 122). Results Of the total 324 children and adolescents with vitiligo, vitiligo vulgaris was the most common type (42.3%) and the most commonly involved site was the face (54.6%). A total of 15 of 254 (5.9%) patients screened for thyroid function were diagnosed with thyroid disease (four had Hashimoto’s thyroiditis; two, Graves’ disease; seven, subclinical hypothyroidism; and two, subclinical hyperthyroidism). None of the 50 patients with segmental vitiligo showed any thyroid dysfunction (P = 0.047). There was no significant difference in the incidence of thyroid disease between children and adolescents with vitiligo and the control group, in which seven of 122 (5.7%) showed thyroid dysfunction. Conclusion In this study, we demonstrated the characteristics of children and adolescents with vitiligo and also observed no significant difference in the incidence of thyroid disease between children and adolescents with vitiligo and the control group.     

Continuous measurement of intra‐oral pH and temperature: development,validation of an appliance and a pilot study

To describe a novel approach for continuous measurement of intra‐oral pH and temperature in individuals carrying out normal daily activities over 24 h. We designed, validated and constructed a custom‐made appliance fitted with a pH probe and a thermocouple. Six subjects wore the appliance over a 24‐h period for two non‐consecutive days, while the intra‐oral pH and temperature were measured continuously and recorded. Intra‐oral pH and temperature were very similar across different recording days, the difference being not statistically significant (P ≥ 0·14). There was a noticeable difference in the pattern of variation of pH between day and night. During the day, the mean pH was 7·3 (±0·4) and dropped markedly only after consumption of acidic food and drinks. The intra‐oral pH decreased slowly during sleep with an average pH of 6·6 (±0·4) being recorded. The difference between day and night was statistically significant (P = 0·002). The mean intra‐oral temperature was 33·9 °C (±0·9) during daytime and 35·9 °C (±0·5) during sleep (P = 0·013) with minor fluctuations occurring over 24 h. The continuous and simultaneous intra‐oral pH and temperature measurement system described in this report is reliable, easy to construct, able to measure variables over a sustained period and may serve as a future diagnostic tool in a number of applications.