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In this article, we report the discovery of a series of pyrimidopyridones as inhibitors of IRAK4 kinase. From a previously disclosed 5-azaquinazoline series, we found that switching the pyridine ring for an N-substituted pyridone gave a novel hinge binding scaffold which retained potency against IRAK4. Importantly, introduction of the carbonyl established an internal hydrogen bond with the 4-NH, establishing a conformational lock and allowing truncation of the large basic substituent to a 1-methylcyclopyl group. Subsequent optimisation, facilitated by X-ray crystal structures, allowed identification of preferred substituents at both the pyridone core and pyrazole. Subsequent combinations of optimal groups allowed control of lipophilicity and identification of potent and selective inhibitors of IRAK4 with better in vitro permeability and lower clearance., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

In this article, we report our efforts towards improving in vitro human clearance in a series of 5-azaquinazolines through a series of C4 truncations and C2 expansions. Extensive DMPK studies enabled us to tackle high Aldehyde Oxidase (AO) metabolism and unexpected discrepancies in human hepatocyte and liver microsomal intrinsic clearance. Our efforts culminated with the discovery of 5-azaquinazoline 35, which also displayed exquisite selectivity for IRAK4, and showed synergistic in vitro activity against MyD88/CD79 double mutant ABC-DLBCL in combination with the covalent BTK inhibitor acalabrutinib., (Copyright © 2020. Published by Elsevier Ltd.)

In this article, we report our investigation of a phenomenon by which bridging morpholines across the ring with one-carbon tethers leads to a counterintuitive reduction in lipophilicity. This effect was also found to occur in piperazines and piperidines and lowered the measured log D 7.4 of the bridged molecules by as much as -0.8 relative to their unbridged counterparts. As lowering lipophilicity without introducing additional heteroatoms can be desirable, we believe this potentially provides a useful tactic to improve the drug-like properties of molecules containing morpholine-, piperazine-, and piperidine-like motifs.

A weak screening hit with suboptimal physicochemical properties was optimized against PFKFB3 kinase using critical structure-guided insights. The resulting compounds demonstrated high selectivity over related PFKFB isoforms and modulation of the target in a cellular context. A selected example demonstrated exposure in animals following oral dosing. Examples from this series may serve as useful probes to understand the emerging biology of this metabolic target.

Starting from lead compound 1, we demonstrate how X-ray structural data can be used to understand SAR and expediently optimize bioavailability in a novel series of AMPA receptor modulators, furnishing 5 with improved bioavailability and robust in vivo activity., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Starting from an HTS derived hit 1, application of biostructural data facilitated rapid optimization to lead 22, a novel AMPA receptor modulator. This is the first demonstration of how structure based drug design can be exploited in an optimization program for a glutamate receptor., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Specific homologous radioimmunoassays for the two major porcine neurophysins have been developed and utilized to measure plasma neurophysins during events known to release vasopressin (dehydration and hemorrhage) and oxytocin (parturition and suckling). During hemorrhage plasma neurophysin I increased 2-25 times and decreased toward basal levels after reinfusion of the blood while plasma neurophysin II was low and showed only minor fluctuations. Neurophysin II was released during parturition and suckling in a pattern similar to that reported for oxytocin release during these events. A rise in plasma neurophysin II occurred towards the end of parturition and spurt release occurred in suckling. The function of neurophysins in the plasma is unknown but porcine neurophysin I has been shown to be released independently into the circulation in response to hemorrhage. Independent release of neurophysin II during parturition and suckling was not demonstrated. In the pig, release of neurophysin I may be associated with vasopressin release and neurophysin II associated with oxytocin release.

The response of the pituitary-testicular axis to LH-RH infusion was investigated in rams from birth to sexual maturity. During early postnatal life ram lambs were responsive to LH-RH stimulation and heightened pituitary sensitivity was observed in rams aged 2-3 months. It is suggested that a change in sensitivity of the pituitary-testicular axis occurs at this time and perhaps represents the time of initiation of the pubertal process.

Depite descriptions of many of the physiological events of early pregnancy in the ewe, the way in which the immunological and endocrine adjustments are brought about is not well understood. Obviously, specific effects--for example, maintenance of the corpus luteum--are brought about by the presence of a conceptus in the uterus. This has led to a search for substances produced by the conceptus or induced by the presence of the conceptus in the uterus which could be involved in establishing pregnancy. This paper describes the presence in sheep of substances associated with pregnancy and discusses the origin and characterization of these substances and their role in ovine pregnancy.

Progesterone releasing intravaginal devices (PRIDs) were used in 4 experiments involving 67 cattle to study the effect of the stage of the oestrous cycle and of oestradiol benzoate (ODB) administration on the time interval from PRID removal to oestrus and/or ovulation. Cows in which PRIDs were inserted on days 2 to 4 of the oestrous cycle for 14 days were subsequently observed by endoscopy to ovulate significantly later than cows given identical treatments on days 13 and 14 of the cycle. The concentration of progesterone was higher in the former group at the time PRIDs were removed and remained at a higher level for 3 days thereafter. The length of the oestrous cycle of untreated heifers was significantly longer than in heifers treated for 12 days with PRIDs only inserted on day 3 of cycle (19.7 v 18.2; p less than 0.01). Treatment with PRIDs inserted for 12 days together with ODB further shortened the cycle length from 18.2 days to 16.9 days (p less than 0.01). The intervals from PRID removal to onset of standing oestrus in heifers treated with PRID only and those treated with PRID and ODB were 80h and 45h, respectively (p less than 0.01); the respective variances were 280 and 4; p less than 0.01). Plasma progesterone concentration, at PRID removal, was 3 times higher in heifers treated with PRID only than in heifers treated with PRID and ODB (p less than 0.01) and the interval from PRID removal to the lowest progesterone value following it was 3.8 ad 1.2 days for the 2 groups, respectively (p less than 0.05). The study indicated that the stage of oestrous cycle at PRID insertion is an important factor which influences the interval from withdrawal of PRIDs to ovulation. The results suggest closer synchronisation would follow insertion in the mid-luteal phase (Day 13 to 14) or use of ODB treatment at the time of insertion of PRIDs.

A controlled study was carried out in the pig to determine the effect on fertility of resecting either the ampullary-isthmic junction or the isthmus. In both treated groups, the nidation index was lower than that in the control animals. The index was not significantly lower in the isthmic resection group than in the ampullary-isthmic junction group. The implications of these findings in terms of fallopian tube physiology and human tubal reconstructive surgery are discussed.

Testosterone (as testosterone enanthate, 250 mg i.m. every 2 wk) was administered to pregnant ewes (n = 16), and injections of vehicle were used in 10 control pregnant ewes between days 75 of gestation and term (day 147). Fetal survival (7 of 16 in the treated group versus 10 of 10 in the controls) and growth (birth weights 4.00 +- 0.51 kg in the treated group versus 5.79 +- 0.93, mean +- SD, in the controls) were markedly impaired by testosterone administration. The mechanism of the testosterone effect is unknown, but could be through metabolism to estrogens by the feto-placental unit. These results imply that alterations in the production or metabolism of androgens by the mother or the feto-placement unit may exert important effects on fetal growth and survival.

A radioimmunoassay for LHRH, MODIFIED FROM THe assay of Nett et al. (J Clin Endocrinol Metab 36: 880, 1973) and characterized in more detail, was applied to the measurement of endogenous plasma LHRH in the peripheral circulation of ewes and women around the time of gonadotropin release. Sensitivity was 1.2 pg/tube. Within- and between-assay coefficients of variation were 10% and 25%, respectively, over the range 10-100 pg/tube. Minimal cross reaction (less than 0.1%) was observed with LHRH analogues tested, except those which had undergone single amino acid alterations in the 4 or 8 positions (62-93%) and in the 1 position (1-3%). Inhibition curves parallel to synthetic LHRH were obtained with these immunoreactive analogs, and with crude hypothalamic and pituitary extracts from 16 cycling ewes and 3 pooled hypothalamic extracts from male rats. LHRH contents of ovine hypothalami and pituitaries ranged from 1.9-10.2 (4.5 plus or minus 2.1, mean plus or minus SD) and 0-27.5 (4.2 plus or minus 7.3, mean plus or minus SD) ng LHRH, respectively, with no obvious correlation between the contents of either tissue. LHRH contents of pooled hypothalami from normal, castrated-hypophysectomized male rats were 4.5, 2.9 and 1. 3 ng/hypothalamus. Recovery of synthetic LHRH added to plasma was quantitative, provided the storage time at 4 and 20 C was minimal. Synthetic LHRH administered to ewes by intravenous infusion or subcutaneous injection was readily detectable in peripheral plasma. The metabolic clearance rates of synthetic LHRH' in 3 sheep were 14, 11 and 14-1/day/kg, respectively. Endogenous immunoreactive material in single, unextracted plasma samples from sheep in various physiological states ranged from 0-400 pg/ml. However, the endogenous plasma immunoreactivity in these samples bone no resemblance to synthetic LHRH added to ovine plasma in that it was stable to gentle heat, and was undetectable after methanol extraction. No endogenous LHRH could be detected in methanol extracts of peripheral plasma obtained from estrous ewes or oophorectomized ewes injected iv with estradiol-17beta (40mug) and bled at 15 min intervals prior to gonadotropin release. Single daily plasma samples obtained from three normal women over their entire menstrual cycles contained no significant levels of endogenous LHRH.

The relationship between the pituitary gland and testis in rams was studied from birth to sexual maturity. The concentrations of LH, FSH and testosterone increased between 5 and 7 weeks of age; the rise was not correlated with any specific cytological change in the testis. An augmented pituitary response to LH-RH was demonstrated as levels of gonadotrophin increased. It is unclear whether this change in sensitivity plays a role in initiation of the pubertal process because Sertoli cell maturation, the earliest detectable change in the seminiferous epithelium, occurs between 17 and 21 weeks of age. Spermatocytes were first seen in biopsies taken at 31-36 weeks and spermatogenesis was established fully by 45 weeks. This second phase of testicular development was characterized by increases in prolactin, testosterone and LH. Leydig cells previously difficult to identify became recognizable at the time of sexual maturation. In newborn rams, castration produced significant increases in LH and FSH levels within 2-3 weeks, but higher basal FSH levels (2- to 3-fold) were observed at 5 than at 3 weeks of age. Cryptorchidism did not elevate LH or FSH significantly during the first year of life. FSH rose after this period to levels 2- to 3-fold higher than in normal rams, while LH and testosterone values remained in the normal range in spite of diminished spermatogenic activity; spermatids were absent and testis size was approximately 60% of that recorded in a normal ram. These studies demonstrate a rise in gonadotrophin and testosterone secretion in rams during the first 5-7 weeks of life, followed by a quiescent period of 8-9 months before a secondary increase occurs coincident with the establishment of sexual maturity.

The levels of plasma LH and FSH were measured in serial blood samples taken at 15-min intervals for 6 h from ewes that had remained fertile after grazing oestrogenic pasture (clover-fertile ewes), from ewes that were permanently affected by clover disease (clover-infertile ewes) and from normal ewes. Two flocks of ewes from different locations were studied. In flock 1, tonic LH secretion (total area under the curve of LH concentration versus time, 1 area unit = 1 ng ml-1 x 1 h) was significantly (P < 0.05) greater in clover-infertile ewes (10.4 area units) during anoestrus than in ewes that had remained fertile after prolonged grazing of oestrogenic clover (5.4 area units). Tonic LH and FSH secretions during the bleeding season and FSH secretion during anoestrus were not significantly different. In flock 2, LH levels during the breeding season were significantly (P < 0.05) elevated in clover-infertile ewes (10.9 area units) compared to normal ewes (5.4 area units) that had never grazed oestrogenic clover. LH secretion in clover-infertile ewes (7.8 area units) was intermediate to that found in infertile and control ewes. Concentrations of FSH, progesterone and ovarian vein oestradiol-17 beta (E2) during the breeding season were similar in the three groups. In another experiment, the positive feedback release of LH following administration of E2 (12.5, 25 or 50 micrograms per ewe) was measured in anoestrous ewes of flock 2. Significantly (P < 0.01) more clover-infertile ewes demonstrated a positive feedback effect than control ewes when given 12.5 micrograms E2 but not when given higher doses. The elevation of LH secretion in permanently affected clover-infertile ewes is inconsistent with the hypothesis that the hypothalamo-pituitary axis of these ewes is less responsive to the negative feedback effect of oestrogen. Furthermore, the patency of the positive feedback loop is consistent with the ability to ovulate.