REM sleep behaviour disorder: an overview

REM sleep behaviour disorder (RSBD) is a recently described parasomnia characterised by a history of excessive nocturnal motor activity and absence of muscle atonia during REM sleep. Only limited literature is available on this condition. The exact prevalence is unclear, but recent studies suggest it might not be an uncommon condition. The elderly are more often affected and there is a male preponderance. While transient RSBD can be seen after taking certain drugs or during drug withdrawal, the chronic type is usually idiopathic or associated with an underlying degenerative neurological condition. It can result in considerable distress and/or serious injury to the patients or their bed partners. Differential diagnoses include sleep-walking, night terrors, nightmares, nocturnal seizures, obstructive sleep apnoea, post-traumatic stress disorder, dissociative states and nocturnal confusional states. The dramatic response to clonazepam highlights the importance of recognition and appropriate treatment of this sleep disorder.     

Patterns of psoriatic arthritis in Orientals

OBJECTIVE: To determine the clinical features of psoriatic arthritis (PsA) in a multiethnic Oriental population and to study the effect of ethnicity on disease patterns. METHODS: A retrospective study of 80 patients with PsA seen at either a rheumatology or dermatology referral center. Patients and case records were reviewed and data abstracted according to a standard protocol. Eighty consecutive patients with psoriasis without PsA seen at the dermatology center were recruited as controls. RESULTS: Asymmetric polyarthritis developing in the 4th decade with an equal male to female ratio was the commonest pattern of arthritis among Chinese, Indians, and Malays. Clinically apparent lumbar spondylitis was significantly more common in Indians than Chinese (10/11 vs 11/20, respectively; p = 0.046), although the prevalence of lumbar spondylitis was similar in all ethnic groups. Eighty-nine percent of subjects required nonsteroidal antiinflammatory drugs and 51% required disease modifying antirheumatic drugs at some time for control of joint disease. PsA was significantly more common among Indians compared to the ethnic distribution of the Singapore population (p < 0.000001). Multiple logistic regression identified Indian ethnicity as a risk factor for the development of PsA (OR 2.39, 95% confidence interval 1.02 to 5.60). CONCLUSION: The commonest pattern of PsA in all ethnic groups was asymmetric polyarthritis. Ethnicity affected the development and presentation of PsA in our series: Indians with psoriasis had double the risk of developing PsA compared to Chinese with psoriasis, and lumbar spondylitis when present in Chinese subjects was asymptomatic in 45%, being detectable only on radiological examination.     

Complex niches favour rational species

On the whole living things evolve from simpler to more complex forms, though not undirectionally. The evolution of more complex species makes the environment more complex and also makes the evolution of even more complex species possible and more selectable. With the evolution of sentients, species can be classified according to their degree of rationality. A more rational species is one whose behaviour (i.e. of its individual members) is controlled (relatively) more by the reward-penalty system than by the automatic, inflexible, programmed responses. In two reasonable simple models, it is shown that a more complex environment favours the evolution of more rational species. This result partly explains the dramatic speed of evolution based mainly on random mutation and natural selection, a speed doubted by creationists.     

Nucleotide sequencing of S-RNA segment and sequence analysis of the nucleocapsid protein gene of the newly isolated Akabane virus PT-17 strain

The nucleotide sequences of the S-RNA of Akabane viruses JaGAr-39, OBE-1, Iriki and the newly isolated PT-17 strains and the Aino virus were determined and compared. The results reveal that the S-RNAs of the four Akabane strains share 96.9% homology in nucleotide sequences. Only one amino acid difference out of the 233 amino acids of the nucleocapsid protein (N) and three amino acid differences in the 91 amino acids of the nonstructural protein (NSs) were found among the Akabane viruses. Amino acid sequences of N and NSs proteins of the Aino virus have approximately 80% identity as compared with the Akabane viruses. The results also demonstrate that the four Akabane viruses and the Aino virus can be clearly differentiated by RFLP (restriction fragments length polymorphism) analysis using RT-PCR generated nucleocapsid protein genes and digested with HaeIII and HindIII. The phylogenetic tree based on the UPGMA (Unweighted Pair Group Method with Arithmetic Mean) analysis of the sequences of nucleocapsid protein genes and the S-DNAs revealed that the newly isolated PT-17 strain is most closely related to Iriki strain, than the JaGAr-39 or OBE-1 strains.     

Cloning and sequencing of the pyrG encoding cytidine 5''-triphosphate synthetase from Mycobacterium bovis BCG

Treatment of estrogen receptor (ER)-negative MDA-MB-468 human breast cancer cells with 10 nM 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induced formation of a nuclear aryl hydrocarbon (Ah) receptor complex as determined by ligand-binding and gel electrophoretic mobility shift assays. TCDD also induced CYP1A1-dependent activity in MDA-MB-468 cells, which represents the first ER-negative Ah receptor-positive human breast cancer cell line that has been identified. Treatment of this cell line with TCDD and related compounds also caused a 50% inhibition of cell growth, which resembled the growth inhibitory effects previously reported for epidermal growth factor (EGF). However, EGF expression is minimal in this cell line and is not induced by TCDD; moreover, EGF and TCDD induced a different pattern of oncogene expression and apoptosis in MDA-MB-468 cells. In contrast, TCDD caused a rapid and sustained induction of transforming growth factor alpha (TGF alpha) gene expression and secreted protein (nearly 2-fold); moreover, the growth-inhibitory effects of TCDD could be blocked by antibodies to the EGF receptor. In a separate experiment, it was shown that TGF alpha also inhibited growth of MDA-MB-468 cells. The results of this study indicate that the mechanism of growth inhibition of MDA-MB-468 cells by TCDD is due to induction of TGF alpha, which is a potent antimitogen in this cell breast cancer line.     

Biological and conformational examination of stereochemical modifications using the template melanotropin peptide, Ac-Nle-c[Asp-His-Phe-Arg-Trp-Ala-Lys]-NH2, on human melanocortin receptors

Examination of conformationally constrained melanotropin peptide (Ac-Nle4-c[Asp5-His-Phe7-Arg-Trp9-Ala-Lys]-NH2) on four human melanotropin receptors (hMC1R, hMC3R, hMC4R, and hMC5R) resulted in identifying the importance of ligand stereochemistry at positions 5, 7, and 9 for agonist binding affinity and receptor selectivity. A trend in ligand structure-activity relationships emerged for these peptides, with the hMC1R and hMC4R possessing similar tendencies, as did the hMC3R and hMC5R. alpha-MSH (Ac-Ser-Tyr-Ser-Met4-Glu-His-Phe7-Arg-Trp-Gly-Lys-Pro-Val-NH2), NDP-MSH (Ac-Ser-Tyr-Ser-Nle4-Glu-His-D-Phe7-Arg-Trp-Gly-Lys-Pro-Val-NH2), and MTII (Ac-Nle4-c[Asp5,D-Phe7,Lys10]-alpha-MSH(4-10)-NH2) were also examined at each of these melanocortin receptors. Interestingly, the linear NDP-MSH possessed greater binding affinity for the hMC3R and hMC5R than did the cyclic analogue MTII. The peptide Ac-Nle-c[Asp-His-Phe-Arg-D-Trp9-Ala-Lys]-NH2 demonstrated the greatest differentiation in binding affinity between the hMC1R and hMC4R (78-fold). Analogue Ac-Nle-c[Asp-His-Phe7-Arg-Trp-Ala-Lys]-NH2 resulted in micromolar binding affinity (or greater) at the hMC3R and hMC5R, demonstrating the importance of D-Phe7 for ligand binding potency at these receptors. Ac-c[Asp-His-Phe-Arg-Trp-Ala-Lys]-NH2 resulted in loss of binding affinity at the hMC5R, implicating the importance of Nle4 (or a hydrophobic residue in this position) for binding to this receptor. Ac-Nle-c[D-Asp5-His-Phe-Arg-Trp-Ala-Lys]-NH2 was unable to competitively displace [125I]NDP-MSH binding at micromolar concentrations on the hMC3R and hMC5R, suggesting the importance of chirality of Asp5 either for ligand-receptor interactions or for orientation of the side chain lactam bridge and the structural integrity of the peptide conformation. Energy calculations performed for these peptides resulted in the identification of a low-energy ligand conformer family that is common to all the ligands. The differences in ligand binding affinities observed in this study are postulated to be a result of different ligand-receptor complexed interactions and not solely to the ligand structure.     

Gastrointestinal involvement in Henoch-Sch?nlein syndrome: CT findings

OBJECTIVE: The purpose of this study was to describe the CT features of gastrointestinal involvement in seven patients with Henoch-Sch?nlein syndrome. CONCLUSION: Although the incidence of Henoch-Sch?nlein syndrome is low, it should be considered when CT scans show multifocal areas of bowel-wall thickening, mesenteric edema, vascular engorgement, and nonspecific lymphadenopathy. It should be considered especially in young patients with acute gastrointestinal symptoms.