GBT440 increases haemoglobin oxygen affinity,reduces sickling and prolongs RBC half‐life in a murine model of sickle cell disease

A major driver of the pathophysiology of sickle cell disease (SCD) is polymerization of deoxygenated haemoglobin S (HbS), which leads to sickling and destruction of red blood cells (RBCs) and end‐organ damage. Pharmacologically increasing the proportion of oxygenated HbS in RBCs may inhibit polymerization, prevent sickling and provide long term disease modification. We report that GBT440, a small molecule which binds to the N‐terminal α chain of Hb, increases HbS affinity for oxygen, delays in vitro HbS polymerization and prevents sickling of RBCs. Moreover, in a murine model of SCD, GBT440 extends the half‐life of RBCs, reduces reticulocyte counts and prevents ex vivo RBC sickling. Importantly, oral dosing of GBT440 in animals demonstrates suitability for once daily dosing in humans and a highly selective partitioning into RBCs, which is a key therapeutic safety attribute. Thus, GBT440 has the potential for clinical use as a disease‐modifying agent in sickle cell patients.     

The intradermal effects of the H3 receptor agonist R α methylhistamine in human skin

We have investigated the possible existence of the H₃ histamine receptor in human skin with the highly selective ligands R α methylhistamine (RAMHA) (H₃ agonist) and thioperamide (H₃ antagonist). We compared the intradermal effects of RAMHA with histamine, and studied their potential modulation by the H₁ antagonist terfenadine, and H₂ antagonist cimetidine. The effects of RAMHA and thioperamide on codeine phosphate-, substance P- and histamine-induced weal and flare responses were also studied. RAMHA produced dose-related weal and flare responses that were approximately 10- and fivefold less, respectively, than responses to histamine. Flare responses to RAMHA were significantly inhibited by oral terfenadine ( P  < 0.05). Weal and flare responses to histamine after oral cimetidine showed much intersubject variation, and cimetidine did not significantly alter either RAMHA- or histamine-induced weal and flare responses. Codeine phosphate-, substance P- and histamine-induced responses were not significantly affected by concurrent administration of RAMHA. Thioperamide was not found to influence codeine phosphate-, substance P-, RAMHA- or histamine-induced effects. RAMHA induces vascular (weal and flare) responses in human skin, and these responses are partially inhibited by terfenadine. There is a trend for RAMHA to have an additive effect to the weal induced by substance P and histamine, although our results largely do not reach statistical significance. Thioperamide does not affect the vascular responses to RAMHA, codeine phosphate, histamine or substance P. We cannot conclude that the effects of RAMHA are induced by H₃ receptors on cutaneous endothelial or mast cells.     

Maze learning and motor activity deficits in adult mice induced by iron exposure during a critical postnatal period

Newborn mice were administered Fe(2+) (iron succinate: 7.5 mg/kg, b. wt) on either Days 3-5, 10-12 or 19-21, or vehicle (saline) at the same times, postnatally. Spontaneous motor behaviour and radial arm maze learning were tested at the age of 3 months. It was found that mice treated with Fe(2+) during postnatal Days 10-12 were markedly hypokinetic during the 1st 20-min test period and hyperkinetic during the 3rd and final 20-min test period. These mice showed an almost complete lack of habituation of spontaneous motor activity parameters to the test chambers. In the radial arm maze, the Days 10-12 treatment group evidenced significantly both more errors in arm choices and longer latencies to acquire all eight pellets; these mice showed also a severe trial-to-trial retention deficit as indexed by retention quotients. These behavioural deficits were observed also in animals treated with Fe(2+) during postnatal Days 3-5, but the effects were less pronounced, indicating the higher susceptibility of the brain for Fe(2+)-induced damage during Days 10-12 postpartum. Treatment with Fe(2+) on Days 19-21 did not induce behavioural alterations in comparison with its respective control (vehicle) group. Analysis of total brain iron content indicated significantly more iron (microg/g) accumulation in the basal ganglia, but not frontal cortex, of mice from the Days 3-5 and 10-12 Fe(2+) (7.5 mg/kg) treatment groups. The contribution of iron overload during the immediate postnatal to later functional deficits seems to implicate symptoms of Parkinsonism but the kinetics of iron uptake to the brain and its regional distribution at this critical period of development awaits elucidation.     

The reactions of articular cartilage to experimental wounding: role of apoptosis

OBJECTIVE: To determine the cellular and matrix responses to experimental wounding of articular cartilage. METHODS: Immature and mature bovine articular cartilage was used as an in vitro model system to study the cellular responses to cartilage wounding. Explant cultures were wounded centrally with a trephine and maintained for up to 10 days. TUNEL labeling together with ultrastructural analyses were used to assess the nature of the observed cell death. In vitro labeling with 3H-thymidine was used to detect cell proliferation, and 2 antibodies (COL2-3/4M and BC-13) were used to detect changes in matrix turnover. RESULTS: Cell death was observed as a response to wounding and was considered to be a combination of necrosis and apoptosis. In immature tissue, cell death was more pronounced, particularly in the articular surface region. Within the area of cell death, many cells that did not die subsequently underwent proliferation. The collagenous network showed evidence of denaturation in the area of the wound, but "aggrecanase" activity was not detected. CONCLUSION: There are 2 contrasting, but related, responses to cartilage wounding--apoptosis and proliferation. In order to improve cartilage repair, future studies need to elucidate the regulatory mechanisms that determine these responses.     

Endometrial morphology in asymptomatic postmenopausal women

Few data are available regarding endometrial histologic features in asymptomatic perimenopausal and postmenopausal women. This study encompasses endometrial biopsy specimens obtained from 801 such women before enrollment in a multicenter study of estrogen-progestin replacement. One endometrial cancer was found (0.13%); four additional biopsy specimens showed atypia (total 0.63%). The endometrium was atrophic in 373 (46.9%), proliferative in 133 (16.7%), secretory in 54 (6.8%), and hyperplastic in 41 (5.2%). Insufficient tissue for diagnosis was obtained in 195 (24.5%). We conclude that the yield for neoplasia is so low that screening endometrial biopsy is not justified in asymptomatic perimenopausal and postmenopausal women.     

Night cough counts and diary card scores in asthma.

A tape recording system for recording night cough in asthmatics at home is described. Objective cough counts and half hour periods containing cough did not correlate with diary card scores awarded to eight children on seven nights each. Night cough diary scores may mislead in the assessment of symptom severity.     

Effects of prior administration of steroids upon recovery from lethal sepsis

The effects upon survival of large doses of steroid administered to dogs prior to challenging them with lethal sepsis was evaluated in this study. Dogs were given 30 milligrams per kilogram of body weight per day of methylprednisolone sodium succinate for one, two or eight days and then were infused with 9.72 +/- 0.35 X 10(9) Escherichia coli per kilogram of body weight. All dogs in group 1 (n equals six) not given steroid died within 25 hours. Of the dogs in group 2 (n equals 12) given one or two doses of steroid previously, 42 per cent permanently survived (more than seven days). All dogs in group 3 (n equals five) given eight daily doses of steroid prior to infusion of Escherichia coli died within 17 hours. Dogs in group 4 (n equals six) were given eight daily doses of steroid prior to infusion of Escherichia coli and treated on the day of infusion of Escherichia coli with a regimen of methylprednisolone and gentamicin sulfate which results in a 100 per cent survival rate when given to dogs that have not received prior treatment with steroid. Thirty-three per cent of the dogs in group 4 permanently survived. One or two daily large doses of steroid did not detrimentally affect survival of the dogs. Eight days of steroid administration suppressed endogenous cortisol production. When the dogs were treated with six hours of steroid-antibiotic therapy, survival benefits were limited.