Development of a highly sensitive, high-throughput, mass spectrometry-based assay for rat procollagen type-I N-terminal propeptide (PINP) to measure bone formation activity.

Type-I procollagen aminoterminal propeptide (PINP) is a useful biomarker for bone formation activity that is used to monitor treatment of bone disorders including osteoporosis. Studies with human patients under long-term therapy for osteoporosis by daily injection of parathyroid hormone (PTH) demonstrated that the circulating level of PINP at 3 months of treatment, measured by radioimmunoassay, was a good predictor for bone mineral density (BMD) at 18 months. It is important to have PINP assays for other species to elucidate processes of bone formation and for the development of new therapeutic options that can enhance bone formation activity. Currently, only a human PINP radioimmunoassay is commercially available for clinical use, which may not be cross reactive with PINP from other species. For example, rat PINP has little amino acid sequence homology to human PINP. Therefore, we developed a new, highly sensitive, high-throughput mass spectrometry-based assay for PINP from rat plasma or serum that does not rely on antibody reagents. Circulating levels of PINP showed age-dependent changes in rats. Prednisolone treatment, which is known to retard bone formation activity, led to a significant decrease in PINP, whereas PTH treatment dose-dependently increased PINP. The throughput of the assay parallels that of most antibody-based assays so that it can handle a large number of samples that are generated from preclinical animal studies. PINP in rats may serve as a biomarker for bone formation activity, and this assay could be instrumental in studying bone physiology in rat experimental models.

Comparison of results from the semiautomated serum bone alkaline phosphatase isoenzyme assay with the periosteal alkaline phosphatase assay for use in rat models.

BACKGROUND: Assessment of bone formation activity is an important component of pharmacologic efficacy and toxicity evaluations for compounds in development for osteoporosis therapies. Antemortem biomarkers of bone formation and remodeling in rodents are uncommon. While the periosteal alkaline phosphatase (ALP) assay is a postmortem and laborious means of testing bone-building activity, the semiautomated ALP isoenzyme assay is an antemortem assay that is performed on an automated chemistry analyzer after 2 simple dilutions of the initial serum sample and a short incubation. OBJECTIVES: The goal of our investigation was to determine if the serum bone ALP (BALP) data obtained from the semiautomated ALP isoenzyme assay had a similar pattern of response when compared with the periosteal ALP (PALP) assay for use in pharmacologic screening in rats. METHODS: Serum and bone tissue samples were obtained from orchidectomized Wistar rats, a model of clinically induced osteoporosis. Subsequent bone formation was initiated via treatment with one of several compounds. In study 1, orchidectomized male rats were given either vehicle, dihydrotestosterone or a testosterone derivative subcutaneously every 4 days for 28 days. In study 2, orchidectomized male rats were given either vehicle or compounds A, B, or C by oral gavage daily for 15 days. Blood and tibias were collected at necropsy. Serum was analyzed for BALP activity using a semiautomated ALP assay. Tibias from the same rats were analyzed for PALP activity. RESULTS: Serum BALP activity paralleled PALP activity within each group when compared with the controls. CONCLUSION: Our data indicate that the semiautomated serum BALP isoenzyme assay may be used as a biomarker of bone-building potential in rat models of osteoporosis. This assay affords many advantages to investigators of musculoskeletal diseases, including the potential to measure multiple data points in a single study.

Prevalence of migraine in patients with a history of self-reported or physician-diagnosed "sinus" headache.

BACKGROUND: Symptoms referable to the sinus area are frequently reported during migraine attacks, but are not recognized in diagnostic criteria. Underrecognition of migraine may be partly attributed to a variable clinical presentation, and migraines with "sinus" symptoms contribute to this problem. This study was conducted to determine the prevalence of migraine-type headache (International Headache Society [IHS]-defined migraine without aura [IHS 1.1], migraine with aura [IHS 1.2], or migrainous disorder [IHS 1.7]) in patients with a history of self-described or physician-diagnosed "sinus" headache. METHODS: During a clinic visit, patients with a history of "sinus" headache, no previous diagnosis of migraine, and no evidence of infection were assigned an IHS headache diagnosis on the basis of headache histories and reported symptoms. RESULTS: A total of 2991 patients were screened. The majority (88%) of these patients with a history of self-described or physician-diagnosed "sinus" headache were diagnosed at the screening visit as fulfilling IHS migraine criteria (80% of patients) or migrainous criteria (8% of patients). The most common symptoms referable to the sinus area reported by patients at screening were sinus pressure (84%), sinus pain (82%), and nasal congestion (63%). CONCLUSIONS: In this study, 88% of patients with a history of "sinus" headache were determined to have migraine-type headache. In patients with recurrent headaches without fever or purulent discharge, the presence of sinus-area symptoms may be part of the migraine process. Migraine should be included in the differential diagnosis of these patients.