Cyclic diguanylic acid behaves as a host molecule for planar intercalators

Cyclic ribodiguanylic acid, c-(GpGp), is the endogenous effector regulator of cellulose synthase. Its three-dimensional structure from two different crystal forms (tetragonal and trigonal) has been determined by X-ray diffraction analysis at 1 A resolution. In both crystal forms, two independent c-(GpGp) molecules associate with each other to form a self-intercalated dimer. A hydrated cobalt ion is found to coordinate to two N7 atoms of adjacent guanines, forcing these two guanines to destack with a large dihedral angle (32 degrees), in the dimer of the tetragonal form. This metal coordination mechanism may be relevant to that of the anticancer drug cisplatin. Moreover, c-(GpGp) exhibits unusual spectral properties not seen in any other cyclic dinucleotide. It interacts with planar organic intercalator molecules in ways similar to double helical DNA. We propose a cage-like model consisting of a tetrameric c-(GpGp) aggregate in which a large cavity ('host') is generated to afford a binding site for certain planar intercalators ('guests').

Molecular modelling studies on the binding of phenylurea inhibitors to the D 1 protein of photosystem II

A hypothetical molecular model of part of the D 1 protein of photosystem II, based on the analogous portion of the L subunit of the Rhodopseudomonas viridis reaction centre, has been used to study the binding of an extended hydrophobic phenylurea inhibitor (N,N-dimethyl-carbamoyl)4-amino-4'-chloro-trans-stilbene) (I) to the QB site. The inhibitor was fitted by eye into a cleft in the site, and a limited part of the inhibitor/D 1 complex was energy minimized. The gross orientation of the inhibitor placed the dimethylurea moiety towards the predicted binding domain of the plastoquinone head group, and the stilbene moiety directed along the quinone isoprenoid side chain binding domain, suggesting a similar pathway of approach of the two molecules from the membrane into the binding site. Binding interactions of the inhibitor included hydrogen bonds to the side chain hydroxyl of ser 264 and the peptide carbonyl group of ala 251, with the side chain hydroxyl of ser 268 as an alternative ligand. Numerous hydrophobic contacts were also possible. Although phenylureas do not bind to reaction centres of Rp. viridis, many of the binding interactions to D 1 could also be detected in Rp. viridis. However, the beta-CH2, and delta-CO2- groups of glu 212 in Rp. viridis are located in the corresponding region of D 1 occupied by the dimethylurea moiety of the inhibitor in our model of its binding to D 1. This may explain why diuron (DCMU) does not bind to Rp. viridis reaction centres.

Antitumor drug nogalamycin binds DNA in both grooves simultaneously: molecular structure of nogalamycin-DNA complex

The three-dimensional molecular structures of the complexes between an interesting antitumor drug, nogalamycin, and two DNA hexamers, d[CGT(pS)ACG] and d[m5CGT(pS)Am5CG], were determined at high resolution by X-ray diffraction analyses. Two nogalamycins bind to the DNA double helix in a 2:1 ratio with the aglycon chromophore intercalated between the CpG steps at both ends of the helix. The nogalose and aminoglucose sugars lie in the minor and major grooves, respectively, of the distorted B-DNA double helix. The binding of nogalamycin to DNA requires that the base pairs in DNA open up transiently to allow the bulky sugars to go through. Specific hydrogen bonds are found in the complex between the drug and guanine bases. We suggest that nogalamycin may prefer GC sequences embedded in a stretch of AT sequences.

Standardized and simplified nomenclature for proteins common to all retroviruses

We propose a revised standardized nomenclature for the proteins common to all retroviruses on the basis of biological function, enzymatic activity, and/or virion location data. (We do not discuss proteins specific for subfamilies or only some retroviruses.)

Investigation of the twinning rate in families with the fragile X syndrome

An excess of twins in families with the Martin-Bell or fra(X) syndrome was noted previously in one family study [Fryns, 1986]. We tried to confirm this observation in a second large sample of families from a different population. We calculated the number of twin births among the total number of live births of known obligate carriers found in fra(X) families ascertained in New South Wales, Australia. We only included births of known sex and excluded triplets. There were 5 male pairs, 3 female pairs and 9 unlike sex pairs of twins born among 752 live births. Thus the twining rate was 1/44 per live birth. We compared this rate to that found in two different types of individuals: 1) the rate of 1/96 which was obtained from the 1985 vital statistics for New South Wales, and 2) the rate 1/75 obtained from a sample of live births of obligate carriers with hemophilia A. The increase in twinning among heterozygotes with the fra(X) was highly significant when compared to the census data (p less than 0.001). However, it was not significantly different from that in the hemophilia data (p less than 0.05) which were collected in the same way as in the fra(X) families.

Investigation of the segregation of the fragile X mutation in daughters of obligate carrier women

Two reports have suggested that over 50% of the offspring of obligate carrier women receive the mutation for the fra(X) or the Martin-Bell syndrome [Webb et al, 1986; Fryns, 1984]. Such a segregation distortion is difficult to assess for the fra(X) syndrome because of incomplete penetrance, variable expression and probable ascertainment biases. We have attempted to evaluate this possible segregation distortion in daughters of obligate carriers in a large sample of sibships ascertained in a survey of New South Wales, Australia. We used two definitions of expression: 1) presence of fra(X) positive cells if daughters were tested cytogenetically, and 2) mental impairment if daughters were not tested cytogenetically. The segregation frequency was estimated in different types of sibships of obligate carriers based on the way they were ascertained. This was done in order to have an internal check on possible ascertainment biases. Among the 189 cytogenetically tested daughters, 81 were fra(X) positive. Among the 97 untested daughters, 24 were mentally impaired in some way. Therefore, the segregation frequency as defined by fra(X) expression and/or mental impairment was 37%. Thus, no evidence was detected for segregation distortion. These data were significantly different than those collected by Webb et al [1986] and scored by the same method as the present data set.

Rheumatic disease in the Nuu-Chah-Nulth native Indians of the Pacific Northwest

The Nuu-Chah-Nulth are a tribe of 2,300 Pacific Northwest native Indians. A retrospective study has identified 157 requiring referral to rheumatologists over 15 years. Rheumatoid arthritis (RA) was found in 23, systemic lupus erythematosus (SLE) in 8, sacroiliitis 5, and Reiter's syndrome 1. Overlap syndromes with combinations of RA, SLE, scleroderma and polymyositis were seen in 9. Other rheumatic disorders included osteoarthritis 10, soft tissue rheumatism 14, and musculoskeletal complaints of known etiology (trauma, infection, neoplasm) 12. The remaining 75 patients suffered from periodic weather dependent joint swelling (52) or polyarthralgia (23) which were sometimes accompanied by features of systemic connective tissue disease. These findings are compared with rheumatic disease in other North American Indians.

Histologic analysis of placental tissue in first trimester abortions

The value of histologic evaluation in the analysis of material from first trimester abortions is not completely defined. We prospectively analyzed placenta and decidua from 75 first trimester, spontaneous abortions to ascertain if morphologic features were predictive of karyotype. The histologic features analyzed included hydropic villus change, villus fibrosis, villus scalloping with trophoblastic invaginations, atypical stromal cells, aggregates of lymphocytes in placenta or decidua, and acute inflammation of placenta or decidua. Normal karyotypes were observed in 44 cases and abnormal karyotypes were demonstrated in 31. The presence of villus scalloping with trophoblastic invagination was significantly associated with abnormal karyotypes, particularly triploidy, and the demonstration of acute inflammation was seen significantly more often in cases with normal karyotypes. We conclude that histology can provide only a suggestion as to the likelihood of an abnormal karyotype; the findings are not specific enough to obviate the need for karyotyping in the individual case.

Preventive screening for the fragile X syndrome

In an Australian population of 1.2 million, we screened 1977 intellectually handicapped persons, who were identified through the public schools and sheltered workshops, for the X-linked semidominant fragile X syndrome. We excluded 527 because they had another known diagnosis. The remaining 1450 were offered chromosomal analysis. Of the 1117 who consented (77 percent), an additional 196 were excluded, and among the 921 who were tested cytogenetically, 40 probands were found. Prevalence rates for persons with an intellectual handicap and the fragile X syndrome in the public school population were 1:2610 for males and 1:4221 for females. Family studies identified 84 women who were either obligate carriers or at high risk of being carriers, who were under the age of 35 and had no children. These women were given genetic counseling, and the availability of antenatal diagnosis was explained to them. If each of these 84 women had two children, 27 of their sons would have an intellectual handicap. We recommend cytogenetic screening for the fragile X syndrome in all currently identified intellectually handicapped people, followed by routine screening of children newly identified as intellectually handicapped in the school system.

Fetal intravascular transfusion for severe erythroblastosis: effects on haematology and survival

Since February 1984, 8 fetuses (including a set of hydropic twins) with severe erythroblasts in the second trimester have received intravascular transfusions guided by ultrasound. These transfusions were associated with a decreasing fetal reticulocytosis, a decreasing proportion of circulating fetal haemoglobin and a decreasing mean fetal red corpuscular volume. All infants were born alive at an average of 5.5 weeks after the first transfusion; 3 infants died, including the hydropic twins and another with lethal congenital anomalies. All 5 survivors required simple transfusions for up to 54 days after birth because of prolonged bone marrow suppression. In severe erythroblastosis in the second trimester, direct intravascular transfusion using ultrasound guidance promises to improve fetal outcome.

New pseudoguaianolides from Gaillardia megapotamica var. scabiosoides

The aerial parts of Gaillardia megapotamica var. scabiosoides afforded known pseudoguaianolides and three new ones. Furthermore, a new guaianolide and an acetylenic sulfoxide were isolated.

Lower Purkinje cell counts in the cerebella of four autistic subjects: initial findings of the UCLA-NSAC Autopsy Research Report

As part of an autopsy research project, the brains of four autistic subjects were examined and compared with those of three comparison subjects without CNS pathology and one with phenytoin toxicity. The cerebellum was selected for initial investigation because pathognomonic symptoms and neurophysiological measures suggest that pathology may exist in the cerebellar-vestibular axis in certain patients. Total Purkinje cell counts were significantly lower in the cerebellar hemisphere and vermis of each autistic subject than in the comparison subjects.

Modification of the projection from the sensory cortex to the motor cortex following the elimination of thalamic projections to the motor cortex in cats

Examination of the projection from area 2 of the sensory cortex to the motor cortex revealed substantial changes following lesion of the ventrolateral nucleus of the thalamus. These observed changes were as follows. (1) The polarity of the evoked potentials elicited by area 2 stimulation reversed in the depth of the motor cortex whereas in normal animals, there was no reversal. (2) The amplitude of area 2-elicited EPSPs in the motor cortical neurons became greater following the lesion of VL. (3) The shape of the observed EPSPs was characterized by multiple peaks whereas in normal animals, the EPSPs were generally smooth and monophasic. (4) Neurons receiving a short-latency input from area 2 were distributed throughout the depths of the motor cortex whereas in normal animals, they were located only in the upper layers (layers II and III). (5) Intracellular injection of HRP revealed that the neurons receiving short-latency input were not restricted to typical stellate type cells, but also included bipolar or bitufted neurons with elongated cell bodies and polarized arborizations. These neurons were located in the superficial (II and III) as well as in the deep (V) layer. It is concluded that the elimination of thalamic input resulted in the reinforcement of the corticocortical input to the motor cortex. The subsequently observed corticocortical projection extended to neurons did not originally innervated by the association fibers. The results suggested that functional recovery following thalamic lesion is partly due to reorganization of projections from the sensory cortex to the motor cortex.

The use of methylprednisolone and metoclopramide in control of emesis in patients receiving cis-platinum

cis-Platinum is a chemotherapeutic agent with benefits often limited by the severe gastrointestinal reactions it produces in nearly all patients. Persistent anorexia, nausea, and vomiting may continue for days after therapy and are poorly controlled by conventional antiemetics. Patients at times refuse continuation of cis-platinum chemotherapy because of these severe gastrointestinal side effects. Intravenous methylprednisolone (Solu-medrol) as well as intravenous metoclopramide (Reglan) have been shown effective in the treatment of chemotherapy-induced nausea and vomiting. This randomized, double-blind study is a comparison of the efficacy of Solu-medrol vs Reglan, as well as, the combination of Solu-medrol and Reglan in the prevention of cis-platinum-induced nausea and vomiting. In this study patients receiving Reglan had better protection from vomiting than patients receiving Solu-medrol (P = 0.0564). Patients receiving the combination of Reglan and Solu-medrol had better protection from vomiting than patients receiving Reglan alone (P = 0.0332), or patients receiving Solu-medrol alone (P = 0.0010). Finally, older patients experienced less vomiting than younger patients, regardless of the anti-emetic drugs used (P = 0.0730).

Insulin release pattern after blockade of catecholamine synthesis with alpha-methyl tyrosine in vivo

Insulin release pattern in vivo was studied using 30 control rats and 30 rats treated with alpha-methyl tyrosine to block catecholamine synthesis in vivo four days before the time of investigation. The drug treated animals exhibited significantly higher fasting insulin levels, and also the first phase insulin release after the B cell was challenged with a glucose load was significantly higher in these animals than occurred in the controls. This observation implies that the B cell is modulated by the sympathetic nervous system in its function and the insulin release would vary according to the emotional state of the individual.

Neue Aromadendren-Derivate aus Wyethia arizonica

Die oberirdischen Teile von WYETHIA ARIZONICA enthalten neben bekannten Verbindungen zwei Aromadendren-Derivate, deren Strukturen durch eingehende spektroskopische Untersuchungen sowie durch Partialsynthese gesichert werden.