Pharmacogenomic information in FDA-approved drug labels: Application to pediatric patients.

Pharmacogenomic (PGx) information is increasingly being incorporated into US Food and Drug Administration-approved drug labels. We reviewed the data source (adults vs. pediatrics) of PGx information in approved drug labels and assessed the suitability of applying adult-derived PGx information and related prescribing recommendations to the care of pediatric patients. We identified 65 drugs with labels containing PGx information and that have also been evaluated in children and found that in the majority of cases (56/65, 86%), the PGx information described was derived from adult studies. The application of PGx information from adults to pediatrics was deemed suitable for 71.4% (n = 40) of the drugs and unclear for 28.6% (n = 16). An ontogeny effect, limited or conflicting data regarding ontogeny of the genetic biomarker, or a difference in the pathophysiology or progression of the adult vs. pediatric disease were the primary reasons for deeming direct application from adults to pediatrics unclear.

Minimally invasive lumbar decompression for lumbar stenosis: review of clinical outcomes and cost effectiveness.

Lumbar stenosis patients typically present with neurogenic claudication or radiculopathy. Studies have shown the benefit of surgical management of lumbar stenosis for patients who fail medical management. Surgical management traditionally involved an open laminectomy and foramenotomies. The emergence of minimally invasive spinal surgery has allowed for comparable clinical outcomes to open laminectomies, with the potential additional benefits of decreased blood loss, shorter hospital stay, decreased postoperative narcotic requirement, decreased rate of infection, and the potential benefit of decreasing the risk of postoperative instability. A shorter length of stay and faster return to work after minimally invasive lumbar decompression may result in the minimally invasive approach being more cost effective than an open approach. A literature review was performed to evaluate the clinical outcomes and cost effectiveness associated with minimally invasive decompression of lumbar stenosis.

The appearance of dural sealants under MR imaging.

Dural sealants are an adjunct to obtain watertight closure after intradural procedures. This study aims to characterize the appearance on MR imaging of 3 commonly employed dural sealants: fibrin glue, PEGH, and BSAG. To this end, patients who underwent spinal intradural procedures that included the use of dural sealant during closure were identified retrospectively. Post-operative data on 15 patients, including complications such as pseudomeningocele formation and infection, were gathered. The appearance of dural sealants on follow-up MR imaging scans within 3 days of surgery was analyzed. Fifteen patients were identified (5 with fibrin glue, 5 with PEGH, and 5 with BSAG applied during closure) with appropriately timed post-operative MR imaging scans. All 3 substances were identifiable based on anatomic location and imaging characteristics on post-operative MR imaging in standard T1, T1 PGFS, and T2 FSE. Definite differentiation between CSF and fibrin glue or PEGH was not possible with the T1 or T1 PGFS, or with the T2 FSE. Differences in intensity between CSF and BSAG were also not significant on either T1 sequence, but they were statistically significant on the T2 FSE. All patients had an uneventful post-operative course, and no patients developed post-operative pseudomeningocele at 30 days. This study concludes that water-based dural sealants such as fibrin glue and PEGH are difficult to differentiate from CSF on standard T1, T1 PGFS and T2 FSE, while BSAG is easily recognized on the T2 FSE. Recognition of water-based sealants therefore requires communication between the neurosurgeon and the neuroradiologist to avoid post-operative misidentification.

The use of imaging in the early development of neuropharmacological drugs: a survey of approved NDAs.

The aim of the study was to evaluate the use of imaging in the development of neuropharmacological drugs. All New Drug Applications (NDAs) approved from 1995 through 2004 in the Division of Neuropharmacological Drug Products at the Food and Drug Administration were surveyed for imaging studies. Imaging literature was also reviewed with respect to antipsychotics and antidepressants. One hundred and six NDAs (35 new molecular entities (NMEs)) were approved; 15 of these NDAs (10 NMEs) had imaging studies. The primary imaging modality was positron emission tomography. Imaging was primarily conducted for drugs used in schizophrenia, depression, multiple sclerosis, and migraine. The majority evaluated receptor occupancy or proof of concept. Examples (including literature) are discussed as pertinent to dosage, efficacy, safety, or further development of a drug or class of drugs. Imaging contributes to optimal clinical development of central nervous system (CNS)-active drugs. Opportunities are available for its broader use, contributing to improved understanding of the clinical pharmacology of CNS-active drugs.

Characterization of the Saccharomyces cerevisiae homolog of the melatonin rhythm enzyme arylalkylamine N-acetyltransferase (EC 2.3.1.87).

Arylalkylamine N-acetyltransferase (AANAT, serotonin N-acetyltransferase, EC ) plays a unique transduction role in vertebrate physiology by converting information about day and night into a hormonal signal: melatonin. Only vertebrate members of the AANAT family have been functionally characterized. Here a putative AANAT from Saccharomyces cerevisiae (scAANAT) was studied to determine whether it possessed the catalytic activity of the vertebrate enzyme. scAANAT is 47% similar to ovine AANAT, but lacks the regulatory N- and C-terminal flanking regions conserved in all vertebrate AANATs. It was found to have enzyme activity generally typical for AANAT family members, although the substrate preference pattern was somewhat broader, the specific activity was lower, and the pH optimum was higher. Deletion of scAANAT reduced arylalkylamine acetylation by S. cerevisiae extracts, indicating that scAANAT contributes significantly to this process. The scAANAT sequence conformed to the three-dimensional structure of ovine AANAT catalytic core; however, an important structural element (loop 1) was found to be shorter and to lack a proline involved in substrate binding. These differences could explain the lower specific activity of scAANAT, because of the importance of loop 1 in catalysis. Data base analysis revealed the presence of putative AANATs in other fungi but not in the nearly complete genomes of Drosophila melanogaster or Caenorhabditis elegans. These studies indicate that the catalytic and kinetic characteristics of fungal and vertebrate enzymes can be considered to be generally similar, although some differences exist that appear to be linked to changes in one structural element. Perhaps the most striking difference is that fungal AANATs lack the regulatory domains of the vertebrate enzyme, which appear to be essential for the regulatory role the enzyme plays in photochemical transduction.

Transforaminal lumbar interbody fusion: technique, complications, and early results.

OBJECTIVE: To demonstrate the safety, surgical efficacy, and advantages of the transforaminal approach for lumbar interbody fusion when combined with pedicle screw fixation. METHODS: We retrospectively reviewed the records of 22 patients (age range, 34-63 yr; mean, 49 yr) with Grade I or II spondylolisthesis who underwent transforaminal lumbar interbody fusion. Nineteen patients presented with low back pain and associated radiculopathy, and three presented with low back pain only. Transforaminal lumbar interbody fusion was performed at L4-L5 in 8 patients, L5-S1 in 11 patients, L3-L4 and L4-L5 in 2 patients, and L4-L5 and L5-S1 in 1 patient. Periodic follow-up took place 1 to 12 months after surgery (mean, 5.3 mo). Decompression is performed according to clinical circumstances. Pedicle screws are placed, and a discectomy is carried out. The cartilaginous endplates are removed. The interspace is gradually distracted, resulting in lost disc height being regained, and interbody fusion cages are positioned. The pedicle screw-and-rod construct is then compressed, restoring lumbar lordosis. RESULTS: Low back pain completely resolved in 16 patients, moderate relief from pain was achieved in 5 patients, and the pain was unchanged in one patient. Nonneurological complications included intraoperative durotomy in one patient and postoperative wound infection in two. In one patient, postoperative mild L5 motor paresis resolved. One patient had a temporary brachial plexopathy due to intraoperative positioning, and one patient had peripheral polyneuropathy secondary to prolonged intraoperative blood pressure cuff inflation. CONCLUSION: Transforaminal lumbar interbody fusion is a safe and effective method for achieving circumferential spinal fusion via a single-stage procedure. This procedure is particularly useful in restoring disc space height and lumbar lordosis.

Spinal chondrosarcoma following adenocarcinoma of the breast: case report.

BACKGROUND: Chest wall chondrosarcomas have been reported rarely in breast cancer patients treated with chest wall radiation therapy. However, there are no prior reports of spinal chondrosarcomas arising in patients with a history of breast adenocarcinoma. CASE DESCRIPTION: A neurologically intact 53-year-old woman with breast adenocarcinoma and new onset back pain was evaluated. Magnetic resonance imaging of the spine revealed a tumor of the posterior elements of T7, impinging upon the spinal cord. A computed tomography guided needle biopsy of the spinal mass failed to yield diagnostic results. The patient underwent an open surgical biopsy and complete excision of a low-grade chondrosarcoma. The patient's thoracic pain resolved after surgical excision of her thoracic tumor. She remained neurologically intact. Pathological examination of the tumor revealed a low-grade chondrosarcoma. CONCLUSION: We present the first reported case of chondrosarcoma of the spine arising in a patient with a history of breast adenocarcinoma without prior irradiation. Solitary spinal tumors in patients with breast adenocarcinoma should not be assumed to be metastatic lesions, and chondrosarcoma should be included in the differential diagnosis of spinal lesions in this patient population. Experimentally, chondrosarcomas have been shown to be sensitive to circulating levels of estrogens, and this might explain an association with adenocarcinoma of the breast treated with tamoxifen.

Microsurgical treatment of symptomatic sacral Tarlov cysts.

OBJECTIVE: Providing relief of symptomatic radiculopathy resulting from sacral perineural cysts has proven difficult. Our goal was to improve the treatment of these cysts with microsurgical cyst fenestration and imbrication, while minimizing functional damage to neural tissues. METHODS: We retrospectively reviewed the records for eight adult patients with large (2-3-cm) sacral perineural cysts who were treated at the University of California, San Francisco, between October 1992 and April 1999. All patients presented with radicular pain that was refractory to medical treatment. Three patients also reported urinary incontinence. We performed sacral laminectomies with microsurgical cyst fenestration and cyst imbrication for all patients, using intraoperative electromyography to minimize damage to the sacral nerve roots. For seven patients, we reinforced the closures with epidural fat or muscle grafts and fibrin glue application. For five patients with cysts that communicated with the subarachnoid space in computed tomographic myelograms, we placed lumbar drains for cerebrospinal fluid diversion for several days postoperatively. We assessed outcomes, using telephone questionnaires and periodic postoperative physical examinations, 3 to 73 months after surgery. RESULTS: After surgery, radicular pain improved markedly for four patients and moderately for three patients; one patient with initial improvement experienced pain recurrence 9 months later. Bladder control improved markedly for two of the three patients with bladder dysfunction. There were no cerebrospinal fluid leaks and no new postoperative neurological deficits. CONCLUSION: Microsurgical cyst fenestration and imbrication are effective treatments for long-term relief of refractory painful radiculopathy and urinary incontinence associated with large sacral perineural cysts.

Tandem B1 elements located in a mouse methylation center provide a target for de novo DNA methylation.

A cis-acting methylation center that signals de novo DNA methylation is located upstream of the mouse Aprt gene. In the current study, two approaches were taken to determine if tandem B1 repetitive elements found at the 3' end of the methylation center contribute to the methylation signal. First, bisulfite genomic sequencing demonstrated that CpG sites within the B1 elements were methylated at relative levels of 43% in embryonal stem cells deficient for the maintenance DNA methyltransferase when compared with wild type embryonal stem cells. Second, the ability of the B1 elements to signal de novo methylation upon stable transfection into mouse embryonal carcinoma cells was examined. This approach demonstrated that the B1 elements were methylated de novo to a high level in the embryonal carcinoma cells and that the B1 elements acted synergistically. The results from these experiments provide strong evidence that the tandem B1 repetitive elements provide a significant fraction of the methylation center signal. By extension, they also support the hypothesis that one role for DNA methylation in mammals is to protect the genome from expression and transposition of parasitic elements.

MR artifact mimicking a temporal lobe lesion in an epilepsy patient.

A ten-year-old healthy child presented with a right upper extremity focal seizure which secondarily generalized. Magnetic resonance imaging (MR) revealed a 1-cm area of abnormal signal intensity in the left posterior temporal lobe at the gray-white junction. This did not appear on all imaging sequences, raising the suspicion of an artifact. Repeat MR revealed no intracranial or extracranial pathology. This case illustrates MR 'wrap around' artifact that mimicked a temporal lobe abnormality in an epilepsy patient. The physics of MR are reviewed as they pertain to this artifact.

The primary function of a redundant Sp1 binding site in the mouse aprt gene promoter is to block epigenetic gene inactivation.

The promoter region of the mouse adenine phosphoribosyltransferase (aprt) gene contains one non-consensus Sp1 binding site at its 5' end followed by three consensus Sp1 binding sites. The two 3'-most binding sites are sufficient for maximal expression of aprt , suggesting that the non-consensus and consensus binding sites at the 5' end are redundant. However, the two 3' sites are not sufficient to block epigenetic inactivation, which led to the hypothesis that the redundant consensus and/or non-consensus 5' Sp1 binding sites are required to block inactivation events. To test this hypothesis, promoter region constructs were made in which the two 5' Sp1 binding sites were mutated alone or in tandem, and then each construct was tested for its ability to withstand epigenetic inactivation. A cis -acting methylation center that is normally located 1.2 kb upstream of the promoter was used to induce inactivation. The results demonstrate that the presence of the redundant consensus Sp1 binding site is required to block methylation-associated gene inactivation. Therefore, the Sp1 binding sites comprising the mouse aprt promoter have evolved two distinct functions, one to promote transcription and the other to block epigenetic inactivation.

Epigenetic gene inactivation induced by a cis-acting methylation center.

In this report we test the hypothesis that a cis-acting methylation center can induce epigenetic gene inactivation. The cis-acting element used is an 838-base pair fragment that was shown previously to provide a de novo methylation signal (Mummaneni, P., Bishop, P. L., and Turker, M.S. (1993) J. Biol. Chem. 268, 552-558). Its normal location is approximately 1.3 kilobase pairs upstream of the mouse aprt (adenine phosphoribosyltransferase) gene. To determine if the methylation center could induce inactivation of the aprt gene, a plasmid construct was created in which the methylation center was moved next to the aprt promoter. Transfection experiments demonstrated inactivation of the aprt gene on the hybrid construct. The inactivation event was shown with a Southern blot analysis to correlate with hypermethylation and to be reversible by treatment with 2-deoxy-5'-azacytidine, a demethylating agent. Interestingly, gene inactivation induced by the methylation center required truncation of the aprt promoter. The results demonstrate that epigenetic gene inactivation can be induced by a DNA methylation center.

A cis-acting element accounts for a conserved methylation pattern upstream of the mouse adenine phosphoribosyltransferase gene.

A 2.1-kilobase pair region located just upstream of the mouse aprt (adenine phosphoribosyltransferase) gene has a methylation pattern that is conserved in mouse tissues and culture cell lines. This upstream region includes four HpaII/MspI sites. Two of these sites are fully methylated, one is partially methylated, and one is unmethylated. Transfection experiments have demonstrated that the conserved methylation pattern can be reproduced in a mouse embryonal carcinoma stem cell line via de novo methylation (Turker, M.S., Mummaneni, P., and Bishop, P.L. (1991) Somat. Cell Mol. Genet. 17, 151-157). To examine the molecular basis of the conserved methylation pattern, a plasmid-based deletion analysis was conducted by removing and rearranging specific portions of the upstream region. Unmethylated versions of these plasmid constructs were then transfected into the mouse stem cell line and the methylation status of the remaining HpaII/MspI sites determined with a Southern blot analysis. By using this approach, a cis-acting sequence within the upstream region of approximately 0.8 kilobase pairs was identified which appears responsible for the conserved methylation pattern. We use the term "de novo methylation center" to denote this sequence. Based on the results obtained, a model is offered to explain the formation of the conserved methylation pattern in the upstream region.

Region- and cell type-specific de novo DNA methylation in cultured mammalian cells.

A region upstream of the mouse adenine phosphoribosyltransferase (aprt) gene has a well characterized methylation pattern for HpaII/MspI sites. When an unmethylated plasmid construct containing this region was transfected into P19 mouse teratocarcinoma stem cells appropriate de novo methylation was observed. However, de novo methylation was significantly reduced when this plasmid was introduced into a differentiated derivative of the P19 stem cell line. Finally, a position effect for de novo methylation was shown by demonstrating methylation of a normally unmethylated HpaII/MspI site when it was placed in this upstream region. This system should prove useful for elucidating DNA signals for de novo methylation and changes in DNA methyltransferase activities that occur during cellular differentiation.