Bombesin analogs containing alpha-amino-isobutyric acid with potent anticancer activity.

Six octapeptide bombesin (BN) analogs were synthesized by substituting alpha-aminoisobutyric acid (Aib), in place of Ala9 or Gly11, or both, in the [D-Phe6, desMet14]-BN (6-14) sequence: D-Phe6-Gln7-Trp8-Ala9-Val10-Gly11-His12-Leu13-NH2 (P0). Additionally, Leu13 was replaced with isoleucine in two analogs and one of the analogs was butanoylated at the N-terminus. The antiproliferative activity of the analogs was tested in vitro on human pancreatic (MiaPaCa-2) and colon cancer (SW620, HT29 and PTC) cell lines using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The analogs demonstrated anticancer activity in the above cell lines at concentrations ranging from 0.01 nM to 1 microM. One of the analogs, P6, was evaluated for in vivo tumor regression in a xenograft model of human primary colon cancer in athymic nude mice and was found to cause significant reduction in tumor volume. NMR and molecular dynamics (MD) simulation studies for this analog revealed the presence of a mixed 3(10)/alpha-helical structure. This study demonstrates that the designed BN analogs retain their anticancer activity after the incorporation of the constrained amino acid, Aib, and are potential molecules for future use in cancer therapy and drug targeting.     

Inbreeding and post-natal mortality in South India: Effects on the gene pool

Consanguineous marriages have been favoured throughout South India for many generations. On theoretical grounds it was proposed that long-term inbreeding would have resulted in the elimination of deleterious, recessive lethal and sub-lethal genes. As part of a newborn screening programme for amino acidopathies, data were collected on the level of inbreeding in the current populations of the cities of Bangalore and Mysore, and on the relationship between consanguinity and mean numbers of liveborn and living children. Mean cnonsanguinity was 32.24%, equivalent to a cuoefficient of inbreeding in the newborns,F = 00271. There were no significant differences between the various inbreeding classes in the number of liveborn or living children, nor was a significant consanguinity-related effect on the proportion of survivors detectable. In the light of these findings, the effects on the gene pool of multiple generations of inbreeding are discussed.     

Effect of D-Penicillamine on iron uptake by isolated rat hepatocytes

d-penicillamine (β,β-dimethylcysteine) promotes the incorporation of iron into isolated rat hepatocytes. The mechanism for doing this remains unknown. No differences in iron distribution between control and treated cells has been observed. Ferritin appears as the main destination of internalized iron in both cases. Therefore, increasing iron storage may appear as a side effect of the use ofd-penicillamine as a therapeutic agent for several diseases.     

Isolation and immortalization of rat pre-type II cell lines

Summary The fetal respiratory distress syndrome is due, in part, to the presence of abundant pre-type II alveolar epithelial cells that have not yet differentiated into mature type II cells. Studies of this syndrome have been limited somewhat by the lack of an adequate in vitro model. In the present study we immortalized pre-type II cells by infecting primary isolates obtained from fetal rat lung with a retroviral construct expressing the adenoviral 12S E1A gene product. The immortalized pre-type II cells retained many of the ultrastructural features typical of pre-type II cells in primary culture, most notably lamellar bodies were not detected and the cells contained abundant stores of glycogen, expressed cytokeratin filaments, and bound the lectinMaclura pomifera. Karyotyping revealed that the cells are diploid. Growth studies demonstrate log phase growth in the presence of serum with a markedly decreased growth rate shortly after the cells reach confluence. Exposure of the immortalized pre-type II cells to hydrocortisone and dibutryl cAMP resulted in the induction of lamellar bodylike organelles; however, these cells did not secrete surfactant or express surfactant protein A. These cells may serve as useful models for some in vitro studies of fetal type II cell maturation or the fetal respiratory distress syndrome, or both.     

Contrasting patterns of genetic structure and evolutionary history as revealed by rnitochondrial DNA and nuclear gene-enzyme variation betweenDrosophila melanogaster andDrosophila simulans

Drosophila melanogaster and its sibling speciesD. simulans have a cosmopolitan distribution. Studies on nuclear gene-enzyme variation from natural populations of these species reveal that the two have almost equal overall heterozygosity, yetD. simulans populations are significantly less differentiated. However, it is not clear whether this difference in population structure represents a difference in the genetic strategy with which they respond to the same adaptive challenges, or is the result of difference in species history. To help answer this question, we have undertaken an intensive survey of restriction fragment length polymorphisms of mitochondrial DNA (mtDNA) fromD. simulans; the results are compared with those fromD. melanogaster. We surveyed 69 isofemale lines ofD. simulans from four continents and seven lines from the Seychelles Islands. Ten restriction enzymes detected 104 restriction sites in the continental mtDNAs, of which only threeHinf1 sites were variable and account for fourHlnf1 (restriction variants) haplotypes. These four variants were all found in geographically distant locations. By contrast, twenty-three haplotypes were observed inD. melanogaster, many of which were observed in only one population. It would seem, therefore, that these two species have had different histories. Specifically, cosmopolitan populations ofD: simulans are probably products of a comparatively recent expansion from a source population in Africa. These results do not negate differences in their genetic strategy of adaptation, but they do show the importance of historical contingency in the present-day pattern of geographic variation.     

Synthesis of glycuronamides of amino acids,constituents of microbial polysaccharides and their conversion into neoglycoconjugates of copolymer type

Glycopyranosiduronic acids, amidically linked to amino acids (alanine, serine, threonine, and lysine) were prepared.O-tert-Butyl andN-tert-butyloxycarbonyl protected amino acidtert-butyl esters were used in ethyl 2-ethoxy-1,2-dihydroquinoline-1-carboxylate promoted condensation with 2-azidoethyl glycosides of glucuronic and galacturonic acid. Reduction of the azido-function followed byN-acryloylation and removal of blocking groups with trifluoroacetic acid gave the target monomers. These were converted into neoglycoconjugates of copolymer type, potentially useful for immunochemical studies.On leave from the Indian Institute of Chemical Technology, Hyderabad, India.     

Floral anatomy ofHypseocharis (Oxalidaceae) with a discussion on its systematic position

The floral anatomy of threeHypseocharis spp. has been studied. The genus resemblesOxalidaceae as well asMonsonia andSarcocaulon of theGeraniaceae. As it is closer toGeraniaceae than toOxalidaceae, it perhaps serves as a connecting link between them.     

Zinc resistance in Neurospora crassa

Three non-identical Zn-resistant strains of Neurospora crassa have been isolated. ZNR-1 and ZNR-2 strains were obtained after repeated subculturing of wild type N. crassa on Zn-containing agar media (8mM and 16mM), while ZNR-3 was isolated after mutagenesis with diethyl sulfate, followed by selection on Zn agar plates (16mM). All three ZNR strains showed two- to threefold resistance to Zn in liquid media when compared with the wild type. However, growth measured by hyphal elongation clearly distinguished between the resistant strains (ZNR-3>ZNR-2>ZNR-1wild). The ZNR-2 and ZNR-3 strains were also cross-resistant to Co, while ZNR-2 alone was cross-resistant to Cu. Both Mg and Fe reversed the growth inhibition caused by Zn; Mg by suppression of Zn uptake and Fe without affecting the same. Assay of catalase, iron-binding siderophores and glutathione in Zn toxicity revealed significant increases in catalase and glutathione levels in the ZNR-2 strain when compared with the wild type. Kinetics of Zn uptake by preformed mycelia showed a rapid initial phase of uptake followed by a slower phase. The rates of Zn uptake measured after leaching surface-bound metal with EDTA revealed that ZNR strains have significantly reduced Zn uptake rates when compared with the wild type. The overall data suggest a partial transport block for Zn uptake as the major mechanism for resistance in ZNR strains. Genetic analysis of ZNR strains showed that in the ZNR-3 strain the znr locus maps close to the mating type locus (mt) of N. crassa LG I, while that of ZNR-1 and ZNR-2 is linked to LG IV associated with chromosomal aberration.     

The effect of chronic chlorpromazine administration on monoamine levels in various regions of rat brain

The neuroleptic drug, chlorpromazine (CPZ) has been shown to exert its antipsychotic effect by blocking post synaptic dopamine receptors. However, its effect on steady state levels of monoamines is still in discrepancy. In the present study, CPZ (4 mg/kg body weight) was administered intraperitoneally to adult Wistar rats chronically for 75 days and the levels of norepinephrine (NE), dopamine (DA) and 5-hydroxytryptamine (5-HT) were assayed in various brain regions by high performance liquid chromatography (HPLC). After the experimental period body and brain weights were not statistically different from controls. NE and 5-HT levels were increased only in hippocampus by 15% (p<0.01) and 16% (p<0.01) respectively. DA levels were consistently increased in cortex by 39% (p<0.001), striatum-accumbens by 18% (p<0.01), hippocampus by 27% (p<0.01), hypothalamus by 34% (p<0.001), cerebellum by 36% (p<0.001) and brainstem by 40% (p<0.001) in CPZ treated rats compared to controls. The results suggest that chronic CPZ administration increases DA levels in almost all regions of brain and reflect the ability of CPZ to preferentially interfere with synaptic transmission mediated by DA in brain. It also suggests that this increase in DA might be responsible for certain side effects seen in patients after chronic CPZ treatment.