Design and synthesis of highly potent and selective cyclic dynorphin A analogs. 2. New analogs

We have designed and synthesized several cyclic disulfide-containing peptide analogs of dynorphin A (Dyn A) which are conformationally constrained in the putative "address" segment of the opioid ligand. Several of these Dyn A analogs exhibit unexpected apparent selectivities for the kappa and mu opioid receptors(s) of the central vs peripheral nervous systems. Thus, incorporation of conformational constraint in the putative "address" segment of Dyn A analogs has resulted in the kappa/mu opioid receptor ligands [L-Pen5,Cys11]Dyn A1-11-NH2 (4), [Cys5,Cys10]Dyn A1-11-NH2 (5), [Cys5,Cys9]DynA1-11-NH2 (6), and [Cys4,Cys9,Arg10]DynA1-11-NH2(7). All of these analogs possess high kappa and mu opioid receptor affinities for the central receptor (guinea pig brain), but effect only weak potency at peripheral kappa and mu opioid receptors (GPI). In fact cyclic dynorphin A analog 4 shows > 19,000-fold differences between central kappa opioid affinity and potency in the guinea pig ileum (GPI). Additionally analog 4 is not an antagonist in the GPI, suggesting possible receptor differences between these sites. Substitution of Tyr1 by Phe1 in the cyclic 1-11 series gave the analog [Phe1,Cys5,Cys11]Dyn A1-11-NH2 (1) that was surprisingly potent in the guinea pig brain binding assay (IC50 = 15.1 nM) at the kappa receptor, but was inactive in the GPI and mouse vas deferens bioassays. D-Ala2 and Tic4 analogs of 1 had lower affinity at brain kappa receptors and had very weak potencies in the GPI and MVD bioassays. On the other hand, [Cys6,Cys10]DynA1-11-NH2 (8), [Cys8,D-Cys13]DynA1-13-NH2 (9), [D-Cys8,D-Cys12]DynA1-13-NH2 (10), and [D-Pro10,Cys5,Cys13]-Dyn A1-13-NH2 (11) were surprisingly potent in the GPI bioassay, though considerable apparent selectivity for central receptors is still retained. The apparent lack of correlation between the pharmacological profiles observed in smooth muscle and in the brain binding assays, particularly with 1 and 4, may suggest the existence of different subtypes of the kappa and mu opioid receptors in the brain and peripheral systems.

Say no to financial help?

With reference to your feature on multiple births and their financial implications (Nursing Standard August 22-28 1990), my concerns are: a) Were the parents informed prior to treatment that multiple births might result?

Taenia taeniaeformis: immunoperoxidase localization of metacestode culture product(s) in hyperplastic gastric mucosa

Rats infected with the hepatic metacestode Taenia taeniaeformis develop an extraordinary gastric hyperplasia. Indirect immunoperoxidase staining localized larval in vitro excretory secretory product specifically in the supranuclear cytoplasm of the epithelial cells lining the pits and glands in the hyperplastic gastric mucosa. The accumulation of this substance in the stomach epithelial cells may be relevant to the gastric hyperplasia induced by tapeworm infection.

Histopathologic changes of uterus following gossypol treatment during early pregnancy in rats

Intramuscular injections of gossypol acetic acid (25 mg in 10% EtOH/kg/day beginning on day 2 of diestrus) disrupted early pregnancy in rats as determined by light and electron microscopy. As in pregnant controls, in the uteri of treated rats increased glandular secretion, stromal hyperemia, and decidual tissue formation were noted at days 3-5 of pregnancy. At day 6, extreme hyperemia and stromal hemorrhage had occurred around well-developed decidual tissue with foci of denuded mucosal surface. There was extravasation of blood into the uterine lumen, which was absent in controls. At days 5 and 6 of pregnancy, electron microscopy revealed shorter and fewer microvilli on the uterine glandular cells in the treated versus the control uterus. Luminal epithelial cells had not undergone the normal changes of pregnancy. These results imply that gossypol administered under our conditions neither prevented nor delayed implantation and formation of decidual tissue in the rat uterine endometrium but continuing development of the endometrium was disrupted at day 6 of pregnancy. This disruption of pregnancy may have resulted from a luteolytic action by gossypol that would not permit full structural differentiation in the rat uterus after implantation.

Gossypol in female fertility control: ovum implantation and early pregnancy inhibited in rats

Intramuscular administration of gossypol to normally cycling female rats induced an irregularity of the cyclic pattern for as long as the treatment was continued. Furthermore, administration of gossypol from days 0 (day of sperm-positive vaginal smear) to 8 of pregnancy prevented the normal maintenance of pregnancy. Serum values of progesterone and estradiol 17 beta in gossypol-treated normally cycling and pregnant rats were significantly lower than the control levels. The supplement of a combination of exogenous progesterone and estradiol 17 beta eliminated the inhibitory effects of gossypol on ovum implantation and the maintenance of pregnancy. Our results indicate that gossypol may have some usefulness in female fertility control.

Kinetic investigations in single muscle fibres using luminescent and fluorescent Ca2+ probes

The Ca2+-sensitive photoprotein aequorin and the Ca2+-dependent fluorescent indicators quin 2 and TnCDANZ have been used to investigate contractile processes in single crustacean muscle fibres. The investigations with quin 2 indicate that the free Ca2+ rises to a maximum value before peak force as with aequorin light (approximately 200 msec delay at 12 degrees C) and subsequently decays more slowly, unlike the majority of the aequorin signal, although an aequorin 'tail' signal remains. The resting quin 2 fluorescence from the cell suggests an upper limit of 348 nM for the resting calcium concentration. Experiments with TnCDANZ indicate that this fluorescence response rises rapidly but then the rate of rise slows to reach a maximum value at a time when peak force is achieved and then the fluorescence signal decays more slowly than force. The latter result implies that Ca2+ is attached to the Ca2+-specific sites of TnC when externally recorded force is small.

High Seas Oil Pollution: Particulate Petroleum Residues in the North Atlantic

The results of a continuing investigation into the occurrence and distribution of particulate petroleum residues on the surface of the North Atlantic are presented. From 1971 to 1974 more than 850 samples were collected from the North Atlantic on transects between the east coast of Canada and South America, the Caribbean, Baffin Bay and surrounding waters, the Labrador Sea, and the Azores. Repeated sampling was carried out in the Gulf of St. Lawrence and the region between Nova Scotia and Bermuda. The results indicate that the waters north of the Gulf Stream–North Atlantic Current system were virtually free from floating petroleum residues, while the waters of the Gulf Stream, Sargasso Sea, and Caribbean Sea were much more heavily polluted. Although concentrations as high as 91.8 mg/m2 were encountered, the general level of pollution was much less with tar contents in southern waters following a lognormal distribution with a geometric mean of 0.16 mg/m2. The geographical distribution of tar is interpreted in terms of inputs from shipping and tanker traffic, and surface circulation patterns.

Dispersed and Particulate Petroleum Residues in the Gulf of St. Lawrence

Concentrations of petroleum residues both as material in solution or dispersed through the water column and as fresh oil or tarry particles floating on the surface in the Gulf of St. Lawrence were measured during July–August 1971. Dissolved and dispersed forms were present in concentrations generally less than 5 μg/liter over the southern and western regions while 5–10 μg/liter were encountered in the north and east. A major source of these residues appears to be the Atlantic water that enters through Cabot Strait, and the distribution of these materials is closely related to the circulation of water within the Gulf. Surface oil was present at approximately 50% of the stations occupied in concentrations generally less than 100 μg/m2 but as great as 12,400 μg/m2 in the vicinity of the sunken barge Whale. There is no evidence to indicate an appreciable change in concentrations to those of a year ago.

Fish School Size and Migration

When a group of fish is migrating as a school, the error in navigation should be smaller as the size of the school increases, if the individuals jointly orient to a group mean direction. An approximation of this effect is available from consideration of the properties of the circular normal distribution.