Stem cells in gastrointestinal epithelium: numbers, characteristics and death

The mammalian intestinal mucosa, with its distinctive polarity, high rate of proliferation and rapid cell migration, is an excellent model system to study proliferative hierarchies and the regulation of cell division, differentiation and cell death. Each crypt contains a few lineage ancestral stem cells (the 'ultimate stem cells'). However, there are other potential stem cells within the early lineage, and many rapidly proliferating transit cells with no stem cell capabilities. Apoptosis under two circumstances has a specificity for the ultimate stem cells in the small intestine and this represents, in one case, part of the stem cell homeostatic process and, in another case, a protective mechanism against DNA damage. Apoptosis occurs with a lower frequency in the large intestine owing to the expression of the bcl-2 gene in this region, and this probably contributes to the causes for the low cancer risk in the small bowel and the high risk in the large bowel. Current studies are beginning to unravel the complex interaction of growth factors and regulatory genes that determine whether a cell divides, differentiates or dies.     

Micro-sequencing strategies for the human A33 antigen, a novel surface glycoprotein of human gastrointestinal epithelium

At the end of the XIXth Century the attitude towards malaria changed dramatically from fatalism and resignation to an active policy that made the eradication of the disease a possible objective. This dramatic change in the scientific political and cultural attitudes towards malaria was the result of two main phenomena: i) the impact of the scientific medicine and Pasteurian revolution on medicine and health policies, and ii) the discovery of the theoretical simplicity of the cycle of malaria transmission and of the possibility to interrupt it, by avoiding the contacts between people and the Anopheles mosquitoes. However, scientifically based strategies against malaria were in place before the discovery of the real causative agents and of the transmission cycle at the end of the XIXth century, as the origin of the scientific medicine had already produced a 'rationale' for local and national campaigns against malaria. According to Tommasi-Crudeli, for example, the cause of malaria was not a 'chemical compound', a 'miasma', but a 'living ferment', specific and autonomous. As a consequence, the aim of antimalarial measures was to eliminate the conditions indispensable to the multiplication of the specific ferment contained in the soil. The theory of malaria aetiology changed after the discovery of the transmission cycle by Ross and Grassi, but the general strategy remained the same: to eliminate one of the factors indispensable to the multiplication and diffusion of the agent. The detailed knowledge of the malaria transmission cycle made it possible to define the exact conditions which were alone responsible for the propagation of the disease and its persistence in the endemic areas. The theoretical linearity and the specificity of the 'Grassi's law' was decisive and produced a fundamental paradigmatic shift in the antimalarial policies. The essential point for the epidemiology and prophylaxis of malaria became to clarify the conditions which contribute to facilitate or to prevent the infection of the Anopheles.     

cDNA cloning, gene expression and secretion of chitinase in winged bean

The role of nitric oxide (NO) in the control of arteriovenous anastomoses (AVAs) has not been studied in vivo in a thermoregulatory end organ. In this study, the effect of local inhibition of NO synthesis by NG-nitro-L-arginine methyl ester (L-NAME) on the microvasculature in the rabbit ear (n=12) was observed in vivo through a chronically implanted ear microvascular chamber. Ear cutaneous blood perfusion (CBP), total auricular arterial flow (TAF), and ear temperature were monitored simultaneously with the direct microvascular observations. Results revealed that intrafacial artery infusion of L-NAME produced significant vasoconstriction of arterioles, AVAs, and venules (p < 0.05). A decrease of ear blood perfusion also was demonstrated by changes of CBP, TAF, and surface temperature. The data provide evidence that basal generation of NO influences the vascular resistance in the thermoregulatory end organ. Moreover, endogenous NO production may be more important in regulating the AVA flow than is flow in other parts of the rabbit ear microvasculature. The effects of NO inhibition on ear microvasculature were not abolished by superior cervical ganglionectomy, indicating that NO production in the rabbit ear is not a neurally mediated mechanism. Further study with a short-term rabbit ear preparation showed that inhibition of NO production with L-NAME enhanced microvascular constrictive responses to extraluminal application of norepinephrine. NO thus appears to play a role of basal vasodilator in opposition to the basal adrenergic vasoconstrictor tone in the rabbit ear.     

Adenocarcinoma arising from the gastrointestinal epithelium in benign cystic teratoma of the ovary

Malignant transformation of benign cystic teratoma of the ovary is rare, with an incidence of 1.8%. The commonest malignant neoplasm to develop is squamous carcinoma (80%). Adenocarcinoma occurs with less frequency, and only one of which has ever been cited to be of gastrointestinal origin. A 38-year-old female underwent TAH-BSO due to a large right ovarian tumor. Microscopically and immunohistochemically, the tumor was defined as mucinous adenocarcinoma originating from gastrointestinal epithelium in benign cystic teratoma.     

Cell stress-regulated human major histocompatibility complex class I gene expressed in gastrointestinal epithelium

Conventional major histocompatibility complex (MHC) class I genes encode molecules that present intracellular peptide antigens to T cells. They are ubiquitously expressed and regulated by interferon gamma. Two highly divergent human MHC class I genes, MICA and MICB, are regulated by promoter heat shock elements similar to those of HSP70 genes. MICA encodes a cell surface glycoprotein, which is not associated with beta 2-microglobulin, is conformationally stable independent of conventional class I peptide ligands, and almost exclusively expressed in gastrointestinal epithelium. Thus, this MHC class I molecule may function as an indicator of cell stress and may be recognized by a subset of gut mucosal T cells in an unusual interaction.     

Transmuting alpha helices and beta sheets

Protein architecture involves two main secondary structural classes: alpha helices and beta sheets. Some natural proteins alter their fold in response to changes in solution conditions or as a consequence of mutation. Here, we discuss recent attempts to induce such conformational changes by design: specifically, the motivation and success of efforts to change one protein fold into a different one in response to the 'Paracelsus Challenge'. The results of such efforts may provide a better understanding of the processes that underlie conformational plasticity in proteins.     

Purification and characterisation of a protein kinase from winged bean

A soluble, cytoplasmic protein kinase was purified from the developing seeds of winged bean (Psophocarpus tetragonolobus) following conventional methods of protein purification including anion-exchange chromatography, gel-filtration and Blue Sepharose chromatography. The purified enzyme consists of a single polypeptide of M(r) 45,000 as determined by SDS-PAGE and gel-filtration chromatography on Sephacryl S-200. The pH optimum of the protein kinase activity was 7.0, while the optimum concentration of Mg2+ was 5 mM. The enzyme utilised casein as an exogenous phosphate acceptor. The conventional modulators of protein kinases, including the cyclic nucleotides, Ca2+ and calmodulin, did not stimulate the purified enzyme. Heparin and spermine, too, had no effect on its activity. Phosphoamino acid analysis revealed that the enzyme transferred the gamma-phosphate of ATP only to serine residues of casein. All these characteristics, taken together, classifies the purified protein kinase as a member of the casein kinase I group of enzymes.     

Organisation and association of kappa-carrageenan helices under different salt conditions

Mixtures of the added salts NaI and CsI can be used to gradually 'tune' the propensity of kappa-carrageenan (KC) helices to aggregate in solution. We show that this method can be used to resolve the molecular events by which helix formation, under certain conditions, leads to gelation. We also present an overview of the various states of aggregation and organisation that appear for helical KC (non-degraded or ultrasonically degraded) when the NaI/CsI ratio and the concentration of KC are varied. A transition to rigid, superhelical rods is found above a well-defined fraction of cesium. This transition is reflected in a range of experimental measurements, such as cryo-transmission electron microscopy, optical rotation, viscometry and small deformation oscillatory measurements. The superhelical-rod state also seems essential for the association of KC with locust bean gum, and locust bean gum is found to stabilise this state. Novel states of KC alone have been found at cesium contents below the transition threshold. Non-degraded KC forms weak gels at sufficiently high concentrations (> ca. 1%). In contrast, ultrasonically degraded KC forms a chiral nematic liquid crystalline phase at sufficiently high concentrations (> ca. 5%) under these salt conditions.     

Rigid and non-rigid kinetic depth effect with rotating discrete helices

To determine any difference of TV viewing attitude between normal and hearing-loss children, 14 normal and 8 sensory impaired infants/toddlers were observed separately in a playroom with a TV set showing a 12-min videotape. All children enjoyed TV and showed clear differences in TV viewing behavior between hearing-loss and auditory normal children. At the beginning of their favorite programs or changes in programs, normal infants/toddlers were quickly aware of the TV sound and turned toward the TV set, where as hearing-loss children remained unaware. Our observation proved the intact hearing of two clients who had not responded to regular infant auditory tests. Moreover, we surveyed 65 hearing-loss children. Only 21% of them began to watch TV at 0 year of age, 50% at 1 year. They did it apparently later than normal infants who began to watch TV mostly before 1 year of age in the Japanese general population. From fitting with a hearing aid, however, most of them began to enjoy TV, watch it longer, have their favorite programs (music, songs, etc.) and turn to face the TV whenever a favorite program began. This suggests hearing acuity is important to enjoy TV. Since TV is already familiar and attractive to most any children, it is a useful and sensitive tool for early detection of hearing-loss children at 6-18 months of age.     

Bronchial epithelium: morphology, function and pathophysiology in asthma

Human bronchial epithelium has a number of mechanical functions, including mucociliary clearance and protection against noxious agents. Bronchial epithelial cells are also able to release a variety of mediators, including cytokines, chemokines, growth factors, and arachidonic acid metabolites, which are able to regulate the recruitment, activation, and differentiation of inflammatory cells. They also modulate the function of the underlying smooth muscle cells by the release or metabolism of bronchoactive mediators. Finally, bronchial epithelial cells may control inflammatory reactions by the release of anti-inflammatory mediators or by the inactivation of pro-inflammatory mediators. Morphological or functional abnormalities of the bronchial epithelium may contribute to the initiation, perpetuation and prolongation of inflammatory processes and thereby to the pathogenesis of asthma. In this review, the morphology of the bronchial epithelium, its function with regard to host defense, and its immunological potential will be reviewed. Alterations associated with asthma will be emphasized.     

Molecular dynamics simulations of isolated helices of myoglobin

The apo form of myoglobin has two non-native stable states that have been experimentally characterized. Investigation of these states has suggested possible folding pathways for myoglobin. We have performed molecular dynamics simulations on solvated isolated helices of myoglobin to investigate the relationship between the intrinsic stabilities of the isolated helices and the structure and folding pathway of apomyoglobin. Analyses of hydrogen bonding and fluctuations from simulations at 298 and 368 K are used to explore the relative stabilities of the helices of myoglobin. The ordering observed is A approximately G approximately H > B > E > F, which mirrors both the experimental equilibrium and kinetic data available for apomyoglobin. The experimental observation that a subdomain comprising helices A, G, and H is an important early intermediate and our result that these helices are the most stable suggest that the intrinsically more stable helices form early in the folding process and that this significantly influences the folding pathway.     

Hairline reconstruction utilizing modified winged V-plastic hair-bearing flaps and focal anastomotic line excisions

BACKGROUND: A large, recurrent basal cell carcinoma involving the left forehead and suprajacent hair-bearing scalp was excised, following which an esthetically acceptable reconstruction of the scalp and hairline margin was accomplished. OBJECTIVE: A method of utilizing two hair-bearing flaps to cover a large defect at the hair-bearing scalp margin will be photographically demonstrated, and the maneuvers to precisely reconstruct the scalp's anastomotic margin with the forehead will be shown and discussed. METHODS: Dual hair-bearing "winged" V-plastic flaps were evolved anteriorly, the two flaps joined, an M-plasty (Webster) was then incorporated to spare hair-bearing scalp posteriorly, and the entire conjoined scalp flap then advanced anteriorly to the forehead. The precise curvatures of the anastomotic line were reestablished by exact excisions of forehead skin underlying the hair-bearing scalp flaps, or amputations of overlying hair-bearing scalp in excess of forehead needs. RESULTS: An esthetically pleasing and reasonably exact reconstruction of the hair-bearing scalp and forehead anastomotic line was accomplished. CONCLUSION: A precise reconstruction of the forehead/scalp margin can be accomplished utilizing a combination of techniques, including hair-bearing "winged" V-plastic flaps, an M-plasty, and the serial removal of segments of both glabrous and nonglabrous skin to reestablish the frontal hairline margin.     

Functional gastrointestinal disorders: psychological, social, and somatic features

BACKGROUND: Helminthic infections induce an IL-4-dependent polyclonal stimulation of IgE synthetization. It is still unclear, however, what role helminths play in allergic sensitization. OBJECTIVE: We sought to determine the relationship between Ascaris-specific IgE and allergic sensitization in a nontropical country. METHODS: In 2 consecutive cross-sectional surveys in 1992-1993 and 1995-1996, data from school entrants (age range, 5 to 7 years), third graders (age range, 8 to 10 years), and sixth graders (age range, 11 to 14 years) were collected. The 2 younger groups were reexamined in the second survey. Data for about 2300 children, including a cohort of 700 subjects, were analyzed. Ascaris IgE and total and specific IgE to inhalant allergens were measured, and skin prick tests were performed. Information about asthma and allergic rhinitis was collected by a questionnaire. RESULTS: Children who were Ascaris-IgE seropositive (>0.35 IU/mL) in both surveys had 10-fold higher levels of total IgE (451 IU/mL vs 45 IU/mL, P < .001) and higher prevalence rates of allergen-specific IgE seropositivity (56.3% vs 26.6%, P < .001). They also had a higher prevalence of allergic rhinitis (12.6% vs 3.7%, P < .001) and asthma (5.7% vs 1.6%, P < .05). In subjects who were Ascaris-seronegative in the first survey but seropositive in the second survey, total and specific IgE increased markedly. Sensitization to Dermatophagoides pteronyssinus increased nearly 3-fold in this group. In contrast, in children who became Ascaris-seronegative, total and specific IgE decreased. CONCLUSIONS: Contact with low doses of helminthic antigen is associated with an increase of total and specific IgE production. Helminthic infections in East German children are not the cause for a low prevalence of allergies in the former East Germany.     

Crystal structure of LacI member, PurR, bound to DNA: minor groove binding by alpha helices

The three-dimensional structure of a ternary complex of the purine repressor, PurR, bound to both its corepressor, hypoxanthine, and the 16-base pair purF operator site has been solved at 2.7 A resolution by x-ray crystallography. The bipartite structure of PurR consists of an amino-terminal DNA-binding domain and a larger carboxyl-terminal corepressor binding and dimerization domain that is similar to that of the bacterial periplasmic binding proteins. The DNA-binding domain contains a helix-turn-helix motif that makes base-specific contacts in the major groove of the DNA. Base contacts are also made by residues of symmetry-related alpha helices, the "hinge" helices, which bind deeply in the minor groove. Critical to hinge helix-minor groove binding is the intercalation of the side chains of Leu54 and its symmetry-related mate, Leu54', into the central CpG-base pair step. These residues thereby act as "leucine levers" to pry open the minor groove and kink the purF operator by 45 degrees.     

Toxic epidermal necrolysis with severe gastrointestinal mucosal cell death: a patient who excreted long tubes of dead intestinal epithelium

TEN is a severe inflammatory disease which is characterized by generalized epithelial destruction. The epidermis is the most common target of TEN, however, any epithelium can be involved. We report a toxic epidermal necrolysis (TEN) patient who excreted long tubes of dead intestinal epithelium. Epidermal keratinocytes and intestinal epithelium were found to undergo extensive apoptosis by TUNEL method. Drugs were speculated as the causative agents for this case, the causative drug has not been identified. In contrast to marked improvement of cutaneous manifestation and hepatic function by methyl prednisolone pulse therapy, the gastrointestinal symptoms did not respond to therapies, and the patient died by heart failure. Present case suggested a pathogenetic mechanism targeting antigens commonly expressed on the gastrointestinal epithelium and epidermis.     

Mannitol, dextromethorphan, and catalase minimize ischemic damage to retinal pigment epithelium and retina

Pyometra is a relatively common event. However, it is extremely rare for this condition to perforate spontaneously into the peritoneum, and to date only 14 cases have been reported in English literature. We recently experienced such a case in a patient with cervical cancer. The clinical features, pathologic findings, diagnosis, therapy, and outcome of these 15 cases were reviewed. Only 5 cases were associated with malignant diseases, consisting of 2 cervical cancers, 2 colon cancers, and 1 endometrial cancer. All of the patients developed generalized peritonitis, and 4 patients died of this. Correct preoperative diagnosis was difficult. Therefore, immediate and appropriate therapy is important.