Group epitope mapping by saturation transfer difference NMR to identify segments of a ligand in direct contact with a protein receptor

A protocol based on saturation transfer difference (STD) NMR spectra was developed to characterize the binding interactions at an atom level, termed group epitope mapping (GEM). As an example we chose the well-studied system of galactose binding to the 120-kDa lectin Ricinus communis agglutinin I (RCA(120)). As ligands we used methyl beta-D-galactoside and a biantennary decasaccharide. Analysis of the saturation transfer effects of methyl beta-D-galactoside showed that the H2, H3, and H4 protons are saturated to the highest degree, giving evidence of their close proximity to protons of the RCA(120) lectin. The direct interaction of the lectin with this region of the galactose is in excellent agreement with results obtained from the analysis of the binding specificities of many chemically modified galactose derivatives (Bhattacharyya, L.; Brewer, C. F. Eur. J. Biochem. 1988, 176, 207-212). This new NMR technique can identify the binding epitope of even complex ligands very quickly, which is a great improvement over time-consuming chemical modifications. Efficient GEM benefits from a relatively high off rate of the ligand and a large excess of the ligand over the receptor. Even for a ligand like the biantennary decasaccharide with micromolar binding affinity, the binding epitopes could easily be mapped to the terminal beta-D-Gal-(1-4)-beta-D-GlcNAc (beta-D-GlcNAc = N-acetyl-D-glucosamine) residues located at the nonreducing end of the two carbohydrate chains. The binding contribution of the terminal galactose residue is stronger than those of the penultimate GlcNAc residues. We could show that the GlcNAc residues bind "edge-on" with the region from H2 to H4, making contact with the protein. Analysis of STD NMR experiments performed under competitive conditions proved that the two saccharides studied bind at the same receptor site, thereby ruling out unspecific binding.

The phenotypic spectrum of CADASIL: clinical findings in 102 cases

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is an increasingly recognized autosomal dominant disorder that leads to cerebrovascular manifestations in early adulthood. This study delineates the phenotypic spectrum and the natural history of the disease in 102 affected individuals from 29 families with biopsy-proven CADASIL. Recurrent ischemic episodes (transient ischemic attack [TIA] or stroke) were the most frequent presentation found in 71% of the cases (mean age at onset, 46.1 years; range, 30-66 years; SD, 9.0 years). Forty-eight percent of the cases had developed cognitive deficits. Dementia (28%) was frequently accompanied by gait disturbance (90%), urinary incontinence (86%), and pseudobulbar palsy (52%). Thirty-nine patients (38%) had a history of migraine (mean age at onset, 26.0 years; SD, 8.2 years), which was classified as migraine with aura in 87% of the cases. Psychiatric disturbances were present in 30% of the cases, with adjustment disorder (24%) being the most frequent diagnosis. Ten patients (10%) had a history of epileptic seizures. To delineate the functional consequences of ischemic deficits, we studied the extent of disability in different age groups. The full spectrum of disability was seen in all groups older than age 45. Fifty-five percent of the patients older than age 60 were unable to walk without assistance. However, 14% in this age group exhibited no disability at all. Kaplan-Meier analysis disclosed median survival times of 64 years (males) and 69 years (females). An investigation of the 18 multiplex families revealed marked intrafamilial variations.

Repair of demyelinated lesions by transplantation of purified O-2A progenitor cells

The transplantation of well defined populations of precursor cells offers a means of repairing damaged tissue and of delivering therapeutic compounds to sites of injury or degeneration. For example, a functional immune system can be reconstituted by transplantation of purified haematopoietic stem cells, and transplanted skeletal myoblasts and keratinocytes can participate in the formation of normal tissue in host animals. Cell transplantation in the central nervous system (CNS) has been proposed as a means of correcting neuronal dysfunction in diseases associated with neuronal loss; it might also rectify glial cell dysfunction, with transplanted oligodendrocyte precursor cells eventually allowing repair of demyelinating damage in the CNS. Here we use co-operating growth factors to expand purified populations of oligodendrocyte type-2 astrocyte (O-2A) progenitor cells for several weeks in vitro. When injected into demyelinating lesions in spinal cords of adult rats, created in such a way as to preclude host-mediated remyelination, these expanded populations are capable of producing extensive remyelination. In addition, transplantation of O-2A progenitor cells genetically modified to express the bacterial beta-galactosidase gene gives rise to beta-galactosidase-positive oligodendrocytes which remyelinate demyelinated axons within the lesion. These results offer a viable strategy for the manipulation of neural precursor cells which is compatible with attempts to repair damaged CNS tissue by precursor transplantation.

N-acetyl-L-cysteine is a pluripotent protector against cell death and enhancer of trophic factor-mediated cell survival in vitro

We have discovered that N-acetyl-L-cysteine (NAC) protects cells against death induced by exposure to noxious stimuli and against programmed cell death (apoptosis) associated with exposure to inadequate amounts of trophic factors. NAC prevented glutamate-induced death of oligodendrocytes and tumor necrosis factor alpha (TNF-alpha)-induced death of oligodendrocytes and L929 fibroblasts. Moreover, suboptimal doses of NAC plus ciliary neurotrophic factor (which also protects oligodendrocytes against TNF-alpha-mediated killing) acted synergistically to protect oligodendrocytes against TNF-alpha-induced death. Protection against death by growth factor deprivation was provided by the combination of (i) NAC, vitamin C, or Trolox (a water-soluble analogue of vitamin E) with suboptimal concentrations of protein trophic factors, (ii) NAC, vitamin C, or Trolox with progesterone, and (iii) NAC with either vitamin C or Trolox; these latter experiments suggest that the addition of tyrosine kinase stimulators is not required to promote cell survival. In all paradigms, NAC was either equally or more effective than the other compounds examined. In light of the long history of therapeutic application of NAC, we suggest that use of this compound may be of interest in conditions where certain toxin-mediated forms of cell death and/or apoptosis contribute significantly to disease.

1st International consensus guidelines for advanced breast cancer (ABC 1)

The 1st international Consensus Conference for Advanced Breast Cancer (ABC 1) took place on November 2011, in Lisbon. Consensus guidelines for the management of this disease were developed. This manuscript summarizes these international consensus guidelines.

Prophylaxis of postoperative relapse in Crohn's disease with mesalamine: European Cooperative Crohn's Disease Study VI

BACKGROUND & AIMS

This study investigated if long-term treatment with high-dose mesalamine reduces the risk of clinical relapse of Crohn's disease after surgical resection.

METHODS

In a prospective, randomized, double-blind, multicenter study, 4 g of mesalamine (Pentasa; Ferring A/S, Vanlose, Denmark) daily was compared with placebo in 318 patients. Treatment was started within 10 days after resective surgery and continued for 18 months. Primary outcome parameter was clinical relapse as defined by an increase in Crohn's Disease Activity Index, reoperation, septic complication, or newly developed fistula. Risk factors for recurrence were prospectively defined to be analyzed in a stepwise proportional hazards model.

RESULTS

Cumulative relapse rates (+/-SE) after 18 months were 24.5% +/- 3.6% and 31.4% +/- 3.7% in the mesalamine (n = 152) and placebo (n = 166) groups, respectively (P = 0.10, log-rank test, 1-sided). Retrospective analysis showed a significantly reduced relapse rate with mesalamine only in a subgroup of patients with isolated small bowel disease (n = 124; 21.8% +/- 5.6% vs. 39.7% +/- 6.1%; P = 0.02, log-rank test). Probability of relapse was predominantly influenced by the duration of disease (P = 0.0006) and steroid intake before surgery (additional risk, P = 0.0003).

CONCLUSIONS

Eighteen months of mesalamine, 4 g daily, did not significantly affect the postoperative course of Crohn's disease. Some relapse-preventing effect was found in patients with isolated small bowel disease.

Ciliary neurotrophic factor and leukemia inhibitory factor promote the generation, maturation and survival of oligodendrocytes in vitro

We have found that CNTF and LIF are pleiotropic modulators of development in the O-2A lineage. Both molecules enhanced the generation of oligodendrocytes in cultures of dividing O-2A progenitors. CNTF and LIF also promoted oligodendrocyte maturation, as determined by expression of myelin basic protein, and could promote oligodendrocyte survival to an extent comparable with insulin-like growth factor-1 or insulin. In addition, LIF and CNTF both promoted the differentiation of O-2A progenitors into type-2 astrocytes but only when applied in the presence of extracellular matrix (EnMx) derived from cultures of endothelial cells. The ability of CNTF and LIF to enhance differentiation of O-2A progenitors along either of the alternative pathways of oligodendrocyte and astrocyte differentiation suggests that these proteins are able to enhance the process of differentiation per se, while the actual path of differentiation promoted is determined by the presence or absence of additional molecules in the extracellular environment.

Dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis in irritable bowel syndrome

Enhanced stress responsiveness has been implicated as a potential mechanism contributing to the pathophysiology of irritable bowel syndrome (IBS), and should be reflected in altered function of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathetic nervous system. Both of these systems can modulate mucosal immune function. The aims of this study were: (i) to characterize the basal circadian rhythm of adrenocorticotropin hormone (ACTH) and cortisol in IBS vs healthy controls; (ii) to compare stimulated ACTH, cortisol and noradrenaline responses to a pelvic visceral stressor (sigmoidoscopy) in IBS and controls; and (iii) to correlate neuroendocrine responses with colonic mucosal cytokine expression and symptoms in IBS. Two separate studies were conducted in women. In Study 1, basal cortisol levels were analysed in 41 IBS and 25 controls using 24-h collections of plasma ACTH and cortisol (q10 min sampling). In Study 2, 10 IBS patients with diarrhoea (IBS-D) and 10 controls underwent sigmoidoscopy with measurements of stimulated neuroendocrine responses and cytokine mRNA expression in colonic tissue. Basal ACTH levels were significantly blunted (P < 0.05), while basal and stimulated plasma cortisol levels were higher in patients. Basal cortisol levels prior to an experimental visceral stressor positively correlated with anxiety symptoms (P < 0.004), but not IBS symptoms. Irritable bowel syndrome patients with diarrhoea had significantly decreased mRNA expression of mucosal cytokines [interleukin (IL)-2, IL-6] in the sigmoid colon vs controls (P < 0.05). Although dysregulations in stress-responsive systems such as the HPA axis and mucosal immune function are demonstrated in IBS, they do not appear to have a primary role in modulating IBS severity and abdominal pain.

X-linked mental retardation: a study of 7 families

Seven families with X-linked mental retardation (MR) have been studied clinically and cytogenetically. All affected males in six of the families were found to have a fragile site on Xq in a number of their peripheral lymphocytes. The fragile site was not seen in any of the affected males in the seventh family. The affected males in the six families with the fragile X had a syndrome characterized by a variable degree of MR, macro-orchidism, a characteristic repetitive, jocular speech, normal body proportions, and large jaws and ears. The fragile X chromosome could only be detected in a proportion of female carriers and its frequency in females was found to be correlated with their mental status to be inversely correlated with their age.

A new approach to the management of epidermoid carcinoma of the anal canal

Until recently most squamous cell carcinomas of the anal canal were treated by radical surgery. Radiation therapy was only considered for palliation in case of inoperable tumors. Important progress has been made in the knowledge of the natural history of the disease and in the field of radiotherapy. Anal canal squamous cell carcinoma should not be treated any longer by the same procedure as adenocarcinoma of the lower rectum, because both these diseases differ markedly. Multimodality therapy with radiotherapy as first approach has been considered. This series of 121 cases treated since 1971 and followed more than three years suggests that three protocols based on irradiation followed or not by surgery should be used according to the extent of the disease. Of the 72 patients with resectable tumor, the five-year survival rate was 65%. Three-quarters of the patients cured had normal anal function. The rate of death from cancer was 18%. The method requires an accurate assessment of the extent of the tumor and of its pelvic lymphatic spread. Great care must be taken in planning treatment in a close cooperation between radiotherapist and surgeon.

Nuclear envelope alterations in fibroblasts from patients with muscular dystrophy, cardiomyopathy, and partial lipodystrophy carrying lamin A/C gene mutations

Mutations in LMNA, the gene that encodes nuclear lamins A and C, cause up to eight different diseases collectively referred to as "laminopathies." These diseases affect striated muscle, adipose tissue, peripheral nerve, and bone, or cause features of premature aging. We investigated the consequences of LMNA mutations on nuclear architecture in skin fibroblasts from 13 patients with different laminopathies. Western-blotting showed that none of the mutations examined led to a decrease in cellular levels of lamin A or C. Regardless of the disease, we observed honeycomb nuclear structures and nuclear envelope blebs in cells examined by immunofluorescence microscopy. Concentrated foci of lamin A/C in the nucleoplasm were also observed. Only mutations in the head and tail domains of lamins A and C significantly altered the nuclear architecture of patient fibroblasts. These results confirm that mutations in lamins A and C may lead to a weakening of a structural support network in the nuclear envelope in fibroblasts and that nuclear architecture changes depend upon the location of the mutation in different domains of lamin A/C.