Omega chain methylated analogs of PGF2 alpha and PGE2

Our previously published prostaglandin (PG) synthesis route, in which the omega-chain is added in the penultimate step, provides facile access to a wide variety of omega-chain variant PG analogs. Each series requires only the synthesis of the appropriate methylated acylphosphonate for the Emmons' condensation. The syntheses of analogs bearing the following methylation patterns are detailed: 15-Me; 17,17-(Me) 2; 17, 17, 20-(Me) 3; 18, 18, 20-(Me) 3; 15, 18, 18, 20-(Me) 4; and 15-OMe-18, 18, 20- (Me) 3. The well-known 16., 16-dimethyl prostaglandins have also been prepared by this sequence. The synthesis of 16, 16-tetramethylene-PG analogs is also described.

Synthesis of macrolide prostaglandin analogs

Prostaglandin analogs of the E- and F2 alpha-functional type, which are constrained to conformations in which the side-chains are close in space and specifically aligned in the terminal portions by covalent bonding, have been synthesized. These analogs are 1, (omega-1)-macrolides. The syntheses proceeded from aldehyde intermediate I via the Emmon's condensation with dimethyl n-(dimethyl-t-butylsilyloxy)2-oxoalkylphosphonate anions (II a or b). The macrolide closures were performed using 2, 2'-dipyridyl disulfide. For the synthesis of 9-ketoprostaglandin macrolides, a free 9-hydroxy is available for oxidation after macrolide closure, so long as the 9-position is protected as the acetate rather than benzoate. Chiroptical data revealed that the conformations of the macrolide prostaglandins are unchanged (relative to the natural unconstrained prostaglandins) in the vicinity of the five-membered ring and the allyl alcohol unit by the formation of the macrolide linkage.

Molecular basis for prostaglandin potency. III. Tests of the significance of the "hairpin conformation" in biorecognition phenomena

Prostaglandin analogs of the PGF2 alpha, 15-epi-PGF2 alpha, and PGE2 type bearing the following methyl substitution patterns -- 15-Me, 16, 16-(Me)2, 17, 17-(Me)2, and 18, 18, 20-(Me)3 -- and analogs constrained to "hairpin" alignment [via 1, (omega-1)-olide formation] and to "non-hairpin" arrangements [via 1, 9- and 1, 15-olide formation] are compared in the following biological assays: contraction of uterine and gastro-intestinal smooth muscle strips, luteolytic antifertility potency in the hamster, binding affinity to two different PGF2 alpha-receptor preparations from bovine corpora lutea, binding to the PGE-specific receptors from rat kidney and liver, inhibition of ADP- induced aggregation of human platelet-rich-plasma, and the effect on rat blood blood pressure. The methylated prostaglandins were also concerted to the corresponding prostacyclins and examined as to action on the platelet and on rat blood pressure. All evidence points to topographically distinct receptors for F2 alpha-, E- and I2- type prostaglandins. Cross-reactivity is reduced in most of the analogs examined. Independent of the target organ or tissue, the receptors show common features based on the functional class of PG recognized. "Hairpin" alignment improves binding (and potency) only for the PGF2 alpha specific assays. PGE-specific binding and potency is disrupted to an increasing extent as the chain branching point is moved further from the 15-hydroxyl center. In contrast 16, 16-dimethylation is particularly disruptive for the PGI2/E1 platelet receptor interaction.

Trans-synaptic modulation of histamine H-1 receptor development in rat brain

To determine whether neuronal histamine influences development of histamine H-1 receptors in the rat brain, neonates were given diphenhydramine, an H-1 antagonist, daily for the first 21 days of postnatal life. In control rats, specific H-1 binding of [3H]mepyramine in whole brain was low at birth and increased progressively toward adult levels by the end of the 3rd week. Animals treated with diphenhydramine showed marked elevations in binding as early as 4 days postnatally and the differences persisted throughout the experimental period. The increased binding in treated rats was specific to treatment with H-1 antagonists (diphenhydramine, mepyramine) as opposed to an H-2 antagonist (cimetidine); the alteration reflected enhancement of the number of binding sites without a change in Kd, a finding indicative of H-1 receptor supersensitivity. Similar results were seen in the hypothalamus, an area rich in neuronal histaminergic projections. Levels of histamine in the hypothalamus were unaffected by diphenhydramine administration until the end of the 3rd week, at which time, increases were noted. After the loading of the hypothalamus with [3H]histamine, release of label by K+ depolarization in vitro (an indirect index of release from the neuronal histamine pool) was readily obtained at all ages and was unaffected by diphenhydramine administration. Diphenhydramine did not alter histamine levels in brain regions in which most of the histamine is non-neuronal. These studies suggest that, even early in the ontogenesis of histaminergic synapses, a sufficient proportion of releasable histamine is associated with histaminergic neurons to enable trans-synaptic modulation of development of histaminergic H-1 receptors; consequently, blockade of these receptors with diphenhydramine results in supersensitivity even at the earliest stages of development.

Experimental cerebral infarction in primates: regional changes in brain histamine content

Histamine levels in different regions of the brain in the primate Macaca Radiata were studied following experimental infarction induced in the basal ganglia by coagulation of the middle cerebral artery. In the basal ganglia an elevation of histamine level was seen probably due to proliferation of mast cells. In the hypothalamus, a main constituent of the ascending histaminergic neuronal pathway, a sharp rise in histamine content occurred in infarcted as well as sham-operated animals: this probably reflects non-specific stress-related alterations. In contrast, the cortical area of the ischemic hemisphere showed a higher elevation of histamine, demonstrating that infarction in one region can cause widespread specific changes in histaminergic systems remote from the infarct. The rise in histamine level at the ischemic site could evoke an increase in microcirculation which might aggravate cerebral edema, while changes in the remote regions may be responsible for some of the neurological deficits following stroke.

Methyl ethers of prostaglandins F2 alpha and I2

Regiospecific monomethyl prostaglandin f2 alpha ethers (at 0-9, 0-11, and 0-15) have been prepared by total synthesis. The 9, 15-bis-ether was also prepared. The 11- and 15-monoethers have been converted to the corresponding prostacyclins. Nuclear Magnetic Resonance (NMR) spectral comparisons indicate conformational changes associated with ether formation; nonetheless, the PGF2 alpha monoethers all retain significant biological activity: 3-420% of natural PGF2 alpha. The 9- and 15- menthyl ethers show increased selectivity for luteolytic activity as measured in the hamster antifertility (HAF) assay. In contrast the prostacyclin ethers are essentially devoid of agonist activity on both the platelet and vasculature. Prostacyclin diastereomers [5a] also lack activity and it appears that any modification at or of the C-11 or C-15 functions reduces receptor binding by at least a factor of 100.

Ontogeny of histaminergic neurotransmission in the rat brain: concomitant development of neuronal histamine, H-1 receptors, and H-1 receptor-mediated stimulation of phospholipid turnover

The ontogeny of histaminergic neurotransmission in the rat brain was studied by assessing development of histamine levels in brain regions, along with H-1 receptor binding of [3H]mepyramine and H-1 receptor-mediated cellular events. In the hypothalamus, which is rich in histaminergic innervation, levels of the amine were low at birth, increased sharply at 8 days of age, and reached adult concentrations shortly thereafter; this pattern is typical of most neurotransmitters. In contrast, regions poor in neuronal histamine showed an initially high histamine level and a subsequent decline with development, as is known to occur during general growth of tissues. The developmental profile of H-1 receptor binding sites resembled that of the neuronal histamine pool, and the increases with age resulted from changes in the number of binding sites without alterations in Kd. Cellular responses to H-1 receptor activation were assessed by determining the stimulation of phospholipid turnover evoked by intracisternally administered histamine, a process that has been shown to involve only the neuronal compartment. Again, the developmental profile was superimposable upon that of H-1 receptor binding and that of hypothalamic histamine levels. These studies indicate that ontogeny of histaminergic neurotransmission is a coordinated process, with simultaneous development of neuronal histamine, its key biosynthetic enzyme, and H-1 receptors coupled directly to cellular events.

Oblique triangular flap: a new method of repair for oblique amputations of the fingertip and thumb

A new method of repair by means of an oblique triangular flap for oblique, lateral or medical losses of fingertips is described. Its indications, technique, advantages, and complications are discussed.

Influence of ethanol on histamine metabolism and release in the rat brain. II. Regions of the histaminergic pathway

Following acute alcohol administration (80-160 mg/100 g body weight) histamine levels of rat brain cortex and thalamus were elevated and histidine decarboxylase activity was decreased. The effect was less pronounced after chronic alcohol treatment (15% v/v in drinking water for 4 weeks). In the striatum there was no change in the metabolic pattern of histamine. Histamine-N-methyltransferase was unaffected in either case. Depolarisation-induced release of histamine was inhibited by alcohol in the hypothalamus, thalamus and cortex. The results indicate that ethanol affects the histamine metabolism and release processes in the histaminergic pathway of the brain.

Tetrahydronorharmane modulates the depolarisation-induced efflux of 5-hydroxytryptamine and dopamine and is released by high potassium concentration from rat brain slices

Tetrahydronorharmane (THN), a compound which occurs in man and in rats is supposed to act as a modulator of 5-hydroxytryptaminergic neurones. It is reported here that THN stimulated the potassium-induced release of the neurotransmitter from brain slices. This suggests enhancement of the efflux as a mechanism for the 5-hydroxytryptamine-like action of THN in pharmacological experiments. Furthermore, THN decreased the potassium-evoked efflux of (3H)-dopamine. This is consistent with the inhibition of dopaminergic neurones by THN as seen previously in various in vivo experiments. Finally it is demonstrated that a high concentration of potassium evokes the efflux of (14C)-THN from brain slices. This finding suggests that THN is taken up into neurones and exerts its modulating action on serotonergic neurones either inside or outside the cell.

Histamine-release in rat gastric mucosa by pentagastrin

The release of histamine from isolated gastric mucosa of the rat was studied by a superfusion model. Pentagastrin increased the basal efflux of histamine in a dose dependent manner. Secretin failed to influence the release of histamine under similar conditions. The results are compatible with the view that in gastric mucosa pentagastrin releases histamine which then may react with the receptors of the parietal cell thus serving as mediator in the acid secretory process.

A rapid and sensitive enzymatic-isotopic method for routine assay of histamine in blood, plasma and biopsy tissue: re-evaluation

The enzymatic-isotopic method for determination of histamine has been reevaluated. Modifications, permitting routine analysis of the amine in blood, plasma and biopsy tissues of various origin have been described; this permits convenient application of the technique in various fields of clinical pharmacology, gastroenterology and immunology.

Regional levels of histamine in rat brain after microwave irradiation: evidence for artifacts in the enzymatic--isotopic assay

Histamine levels in the brain, measured fluorimetrically, were similar for rats killed by decapitation and microwave irradiation. However, enzymatic--isotopic assay yields 5--20 times higher value for microwave irradiation versus decapitation. Thin layer chromatography of the methylated products in the enzymatic--isotopic assay indicated the formation of artifacts following microwave irradiation. The results strongly suggest that a combination of microwave irradiation and enzymatic--isotopic assay is not suitable for histamine analysis in the rat brain.

Ethanol-induced alterations in histamine content and release in the rat hypothalamus

In the rat hypothalamus, histamine content and histidine decarboxylas: activity are enhanced significantly after acute administration (80--160 mg/100g body weight) of ethanol. The effects are less pronounced after chronic treatment (15% v/v in drinking water for 4 weeks). Histamine methyltransferase is unaffected in either case. In hypothalamic slices preloaded with 3H-histamine and superfused with amine free solution the basal and K+-induced efflux of 3H-histamine are inhibited by alcohol. The inhibition of histamine release along with the increased levels of histamine may play an important role in the central effects of alcohol.

Lysine acetylisalicylate inhibits the protein synthesis in the rat gastric mucosa in vivo and in vitro

Lysine acetylsalicylate (LAS), a water soluble derivative of acetylsalicylic acid and parenterally administrable analgesic, locally inhibits the incorporation of 14C protein hydrolysate into proteins of the rat isolated gastric mucosa. A similar effect on protein synthesis was observed after s.c. administration of the drug, whereas DNA and RNA synthesis were not affected. Obviously, LAS inhibits the translation step during biosynthesis of proteins. It is conceivable that this effect contributes to the potential ulcerogenic action of acetylsalicylate and that parenteral administration is not a criteria to protect the stomach from salicylate-induced side effects.

Gastric mucosal histamine in duodenal-ulcer patients: release by secretin

In 5 duodenal-ulcer patients with anaphylactic skin reaction to intradermal secretin and in 4 healthy controls, biopsy samples from the fundic region of the stomach were superfused with phosphate buffer alone and with phosphate buffer containing 20 C.U./ml synthetic secretin. In response to secretin, the mucosa from duodenal-ulcer patients released significantly increasing amounts of histamine (P is less than 0.05) whereas control tissue did not respond. Additionally, in duodenal-ulcer patients the histamine content of untreated gastric mucosa was about twice as high as in controls (P is less than 0.02). It is suggested that the elevated mucosal histamine could account for the basal and stimulated gastric hypersecretion of duodenal-ulcer patients. In addition, the results are compatible with the concept that in a certain type of duodenal ulceration, secretin does drive rather than inhibit gastric secretion.

Acid releases motilin from human duodenum in vitro

The effect of hydrochloric acid and sodium hydroxide on motilin release from human duodenal mucosa was studied in vitro. Tissue was incubated in 2 ml chambers continuously perfused with medium and was exposed repeatedly to the stimuli. Motilin released into the medium was determined by a specific radioimmunoassay. Whereas alkalinisation abolished basal motilin release, acidification resulted in a 14-fold increase of peptide secretion. The results indicate that motilin secretion can be stimulated in vitro and that the perfusion system described may be a useful tool in studying the mechanism of gastrointestinal hormone release.

Influence of enkephalin on K+-evoked efflux of putative neurotransmitters in rat brain. Selective inhibition of acetylcholine and dopamine release

In rat brain slices preincubated with various radiolabelled putative neurotransmitters, methionine-enkephalin diminished the potassium-evoked release of dopamine and acetylcholine. The effect was antagonised by naloxone. The potassium-induced effux of three other neurotransmitters, histamine, 5-hydroxy-tryptamine and gamma-aminobutyric acid, were unaffected by methionine-enkephalin. A probable physiological function for the endogenous ligands in specifically affecting the catecholaminergic and cholinergic transmission is suggested.

Modulation by histamine of the efflux of radiolabeled catecholamines from rat brain slices

Histamine induced a dose-dependent stimulation of 3H-catecholamine(CA) efflux (superfusion procedure) from hypothalamic, striatal, hippocampal and cortical slices. The extra-hypothalamic regions were the most sensitive to histamine. Efflux of 14C-GABA and 14C-(acetyl)choline was not affected. The effect of histamine on 3H-CA efflux developed slowly, reaching its maximum after 15-20 min. Histamine was inefffective with tissue from reserpinized animals. The major part of the radioactivity released by histamine consisted of CA metabolites. Histamine apparently does not enter catecholaminergic neurons, since tyramine and the CA had no effect on the efflux of 3H-histamine previously taken up by brain slices. After incubation of slices with 3H-CA in the presence of histamine and subsequent superfusion, tyramine or K+ -depolarization induced much less 3H-CA release than from control slices not incubated with histamine. It is suggested that histamine may act as a modulator of presynaptic catecholaminergic processes in the central nervous system by causing a depletion of the transmitter stores in the nerve terminals.

Secretin-induced histamine release in duodenal-ulcer patients

Because a majority of duodenal-ulcer patients responded locally to intradermal secretin, skin samples from 7 patients with duodenal ulceration and 6 patients with goitre or cholelithiasis were incubated with "tris" buffer alone and with tris buffer containing 20 C.U./ml synthetic secretin or 100 microng/ml compound 48/80. Skin from duodenal-ulcer patients released significantly more histamine than did that of controls (p less 0-01). Histological examination of skin samples from these patients showed that the number of histamine-containing mast-cells averaged 5-7 per field and dropped to 1-2 per field after incubation with secretin. It is concluded that in a certain type of duodenal ulceration intradermal secretin releases histamine from mast-cells and thus induces a local anaphylactic reaction. This might prove suitable for preclinical ulcer diagnosis and/or for detection of patients at risk of acquiring that disease.

Enkephalins inhibit intestinal motility: mode of action

In the guinea pig isolated terminal ileum the opioid pentapeptides, methionine-enkephalin and leucine-enkephalin, dose-dependently inhibit contractile responses induced by electrical field stimulation releasing endogenous acetylcholine, and by specific noncholinergic compounds including histamine, barium chloride, and beta-acetyl-digoxin. Tissue levels of cAMP and cGMP remain unchanged. We conclude that enkephalins exert their effects by a direct action at or within the muscle cell and may play a physiological role in the local control of the gut smooth muscle motility.

Potassium-induced release of tritiated histamine from rat brain tissue slices

The release of exogenous histamine was studied by superfusing brain slices following incubation with the radiolabeled amine. Histamine was released in a calcium-dependent way by 40 mM potassium. This release was high in hypothalamus and striatum and low in hippocampus and cortex. Compound 48/80, a mast cell histamine releasing agent, also induced histamine release, but only from hypothalamic tissue slices. It is suggested that the potassium-induced release of accumulated exogenous histamine is mainly from glial cells.

An epidemiologic study of osteogenic sarcoma in Malaysia. Incidence in urban as compared with rural environments and in each of three separate racial groups, 1969-1972

To explore the possibility that environmental and/or genetic factors may yield clues to the etiology of osteogenic sarcoma, an epidemiologic retrospective study of all cases of osteogenic sarcoma in a country with clear geographic and racial variables (Malaysia) was conducted covering a 4-year period. Sixty-eight cases were identified (+85% of the predicted total). The incidence (cases per 100,000 population per year) was 0.11 in Malay, 0.23 in the Chinese, and 0.23 in the Indian. The urban versus rural incidence in the Malay was 0.22 versus 0.09, and in the Chinese 0.31 versus 0.18. The Indian population was too small when dividied into urban and rural segments to be significant.

Effect of ascorbic acid on histamine metabolism in scorbutic guinea-pigs

1. In guinea-pigs fed an ascorbic-acid-free diet, as the ascorbic acid levels decreased the histamine levels in blood and urine rose steadily to maxima in about 10-12 days. The elevated histamine levels persisted in the blood and urine of scorbutic guinea-pigs and the histamine levels in lung, gastric mucosa and spleen also increased. The increased histamine content of the urine, blood and other tissues in the ascorbic-acid-depleted condition could be brought back to normal levels by administration of a single dose of ascorbic acid 5 mg/100 g body wt. guinea-pig. 3. The drop in the elevated histamine level was not due to an indirect effect of ascorbic acid on histamine forming capacity, histaminase activity or histamine release.

Nutrient interrelationship of ascorbic acid and iron in rats and guinea pigs fed cereal diets

Iron at a daily dose of 5 mg per animal was toxic to rats and guinea pigs fed unfortified whole wheat flour and whole rice flour diets. In rats, a species capable of synthesizing ascorbic acid, iron supplementation resulted only in decreased growth. In guinea pigs, iron administration resulted not only in decreased growth but also in high mortality. The apparent toxicity of iron was not observed when wheat flour was fortified with 15% casein. In guinea pigs, administration of ascorbic acid (k mg per 100 g body weight per day) along with iron not only counteracted the toxic effect of iron, but also led to a greater utilization of iron as revealed by increased hemoglobin and serum iron levels accompanied by decreased spleen iron content. Iron administration, however, resulted in decreased ascorbic acid synthesis (in rats only) and increased ascorbic acid utilization as revealed by lowered urinary, blood, and other tissue levels of the vitamin.

Growth and ascorbic acid metabolism in rats and guinea pigs fed cereal diets

The nutritional values of the whole grain principal cereals, namely, wheat, rice, corn, and a millet bajra, were investigated by growth studies and studies on ascorbic acid metabolism in rats and guinea pigs. Growth was markedly retarded by feeding the rats unfortified whole grain cereals. Among the whole grain cereals, rice provided the lowest nutritional value, and the cooking of rice affected the nutritional value further. In weanling rats, ascorbic acid synthesis at the subcellular level was inhibited, and tissue storage of ascorbic acid was decreased in rats fed whole grain cereals. In guinea pigs fed whole grain cereals, the utilization of ascorbic acid was increased. Ascorbic acid supplementation at various levels indicated that the requirement for ascorbic acid increased five times in guinea pigs fed whole grain cereals. The increased intake of the vitamin was not needed when the whole grain cereals were enriched with 15% casein.