Publications

ATP8B1 deficiency is caused by autosomal recessive mutations in ATP8B1, which encodes the putative phospatidylserine flippase ATP8B1 (formerly called FIC1). ATP8B1 deficiency is primarily characterized by cholestasis, but extrahepatic symptoms are also found. Because patients sometimes report reduced hearing capability, we investigated the role of ATP8B1 in auditory function. Here we show that ATP8B1/Atp8b1 deficiency, both in patients and in Atp8b1(G308V/G308V) mutant mice, causes hearing loss, associated with progressive degeneration of cochlear hair cells. Atp8b1 is specifically localized in the stereocilia of these hair cells. This indicates that the mechanosensory function and integrity of the cochlear hair cells is critically dependent on ATP8B1 activity, possibly through maintaining lipid asymmetry in the cellular membranes of stereocilia.

CONTEXT

Patients with persistent primary hyperparathyroidism (PHPT) after parathyroidectomy or with contraindications to parathyroidectomy often require chronic treatment for hypercalcemia.

OBJECTIVE

The objective of the study was to assess the ability of the calcimimetic, cinacalcet, to reduce serum calcium in patients with intractable PHPT.

DESIGN

This was an open-label, single-arm study comprising a titration phase of variable duration (2-16 wk) and a maintenance phase of up to 136 wk.

SETTING

The study was conducted at 23 centers in Europe, the United States, and Canada.

PATIENTS

The study included 17 patients with intractable PHPT and serum calcium greater than 12.5 mg/dl (3.1 mmol/liter).

INTERVENTION

During the titration phase, cinacalcet dosages were titrated every 2 wk (30 mg twice daily to 90 mg four times daily) for 16 wk until serum calcium was 10 mg/dl or less (2.5 mmol/liter). If serum calcium increased during the maintenance phase, additional increases in the cinacalcet dose were permitted.

MAIN OUTCOME MEASURE

The primary end point was the proportion of patients experiencing a reduction in serum calcium of 1 mg/dl or greater (0.25 mmol/liter) at the end of the titration phase.

RESULTS

Mean +/- sd baseline serum calcium was 12.7 +/- 0.8 mg/dl (3.2 +/- 0.2 mmol/liter). At the end of titration, a 1 mg/dl or greater reduction in serum calcium was achieved in 15 patients (88%). Fifteen patients (88%) experienced treatment-related adverse events, none of which were serious. The most common adverse events were nausea, vomiting, and paresthesias.

CONCLUSIONS

In patients with intractable PHPT, cinacalcet reduces serum calcium, is generally well tolerated, and has the potential to fulfill an unmet medical need.

PURPOSE

Black patients have worse prognoses than whites with breast or colorectal cancer. Mechanisms underlying such disparities have not been fully explored. We examined the role of hospital factors in racial differences in late mortality after surgery for breast or colon cancer.

METHODS

Patients undergoing surgery after new diagnosis of breast or colon cancer were identified using the Surveillance Epidemiology and End Results-Medicare linked database (1995 to 2005). The main outcome measure was mortality at 5 years. Proportional hazards models were used to assess relationships between race and late mortality, accounting for patient factors, socioeconomic measures, and hospital factors. Fixed and random effects models were used to account for quality differences across hospitals.

RESULTS

Black patients, compared with white patients, had lower 5-year overall survival rates after surgery for breast (62.1% v 70.4%, respectively; P < .001) and colon cancer (41.3% v 45.4%, respectively; P < .001). After controlling for age, comorbidity, and stage, black race remained an independent predictor of mortality for breast (adjusted hazard ratio [HR] = 1.25; 95% CI, 1.16 to 1.34) and colon cancer (adjusted HR = 1.13; 95% CI, 1.07 to 1.19). After risk adjustment, hospital factors explained 36% and 54% of the excess mortality for black patients with breast cancer and colon cancer, respectively. Hospitals with large minority populations had higher late mortality rates independent of race.

CONCLUSION

Hospital factors, including quality, are important mediators of the association between race and mortality for breast and colon cancer. Hospital-level quality improvement should be a major component of efforts to reduce disparities in cancer outcomes.