Potent, Gut-Restricted Inhibitors of Divalent Metal Transporter 1: Preclinical Efficacy against Iron Overload and Safety Evaluation

Divalent metal transporter 1 (DMT1) cotransports ferrous iron and protons and is the primary mechanism for uptake of nonheme iron by enterocytes. Inhibitors are potentially useful as therapeutic agents to treat iron overload disorders such as hereditary hemochromatosis or β-thalassemia intermedia, provided that inhibition can be restricted to the duodenum. We used a calcein quench assay to identify human DMT1 inhibitors. Dimeric compounds were made to generate more potent compounds with low systemic exposure. Direct block of DMT1 was confirmed by voltage clamp measurements. The lead compound, XEN602, strongly inhibits dietary nonheme iron uptake in both rats and pigs yet has negligible systemic exposure. Efficacy is maintained for >2 weeks in a rat subchronic dosing assay. Doses that lowered iron content in the spleen and liver by >50% had no effect on the tissue content of other divalent cations except for cobalt. XEN602 represents a powerful pharmacological tool for understanding the physiologic function of DMT1 in the gut. SIGNIFICANCE STATEMENT: This report introduces methodology to develop potent, gut-restricted inhibitors of divalent metal transporter 1 (DMT1) and identifies XEN602 as a suitable compound for in vivo studies. We also report novel animal models to quantify the inhibition of dietary uptake of iron in both rodents and pigs. This research shows that inhibition of DMT1 is a promising means to treat iron overload disorders.

Real-time I-MR-imaging--guided cryoablation of uterine fibroids

In an ongoing prospective clinical trial, two patients with large, symptomatic uterine fibroids were treated with percutaneous magnetic resonance (MR)-imaging--guided cryoablation. Patients were followed with serial MR imaging studies and clinical evaluation according to Institutional Review Board protocol. Short-term imaging and clinical data were collected to assess the effects of the therapy. Both patients confirmed a significant reduction or elimination of their symptoms at 2 weeks after cryoablation. Measurements obtained from MR imaging performed after cryoablation documented a 65% and 53% reduction in each patient's fibroid volume at 8 weeks. Early clinical and imaging results confirm MR-imaging--guided cryoablation was effective at reducing or relieving these two patients' symptoms related to uterine fibroids and post-cryoablation imaging confirmed a significant reduction in fibroid volume.

Calcium oxalate stones in feline littermates

Two feline littermates were diagnosed with calcium oxalate uroliths. Both had been maintained on a commercially available dry diet with reduced magnesium and urine acidifying properties. One female littermate was diagnosed by visualising the stones by radiographs while the second littermate, also female, became blocked when one of the uroliths lodged in the urethra. Two other, unrelated cats in the household, of similar age and raised under the same conditions, did not develop calcium oxalate uroliths.

Better maternal outcomes are achieved with dexamethasone therapy for postpartum HELLP (hemolysis, elevated liver enzymes, and thrombocytopenia) syndrome

OBJECTIVE

Our purpose was to determine whether the routine initiation of dexamethasone therapy in patients with postpartum HELLP (hemolysis, elevated liver enzymes, and thrombocytopenia) syndrome produces specific and general therapeutic benefits.

STUDY DESIGN

In this retrospective, analytic study the puerperal courses of 43 women with postpartum HELLP syndrome who were treated with dexamethasone were compared with those of 237 similar patients who did not receive corticosteroids. Dexamethasone 10 mg intravenously at 12-hour intervals was given until disease remission was noted in treated patients, at which time up to two additional 5 mg intravenous doses were given at 12-hour intervals.

RESULTS

The two patient groups were similar in regard to mode of delivery, gestational age, parity, and frequency of eclampsia. Compared with control subjects, dexamethasone-treated postpartum patients were more ill with significantly higher (p < 0.05) admission mean arterial blood pressure, higher serum uric acid level, and severe proteinuria. Dexamethasone administration was associated with a more rapid normalization of platelet counts and lactic dehydrogenase values. Most impressive was a clinically significant reduction of indicated transfusion and respiratory therapy, invasive hemodynamic monitoring, infectious or bleeding-related morbidity, and length of postpartum hospital course.

CONCLUSIONS

Patients who received dexamethasone for postpartum-onset HELLP syndrome experienced a shorter disease course, faster recovery, less morbidity, and less need for other interventionist therapy compared with patients with HELLP syndrome who did not receive dexamethasone.

Reverberation as a parameter in clinical testing

Word identification was measured binaurally and monaurally using the Modified Rhyme Test under noise and reverberation. Normally hearing and hearing-impaired subjects were tested. A change in reverberation time from 0.25 to 0.50 s in a small audiometric room caused a significant change in word identification scores in both groups of subjects. A simulated reverberation composed of five distinct reflections did not affect word identification. The binaural advantage (difference between the binaural and monaural scores) was significant for normally hearing subjects, while it was not significant for hearing-impaired subjects.