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Brenda Banwell

Publications and source records attributed to Brenda Banwell.

8 recordsLinked to original sources
PubMed2026

Proportionality-based association metrics in count compositional data.

Compositional data comprise vectors that describe the constituent parts of a whole. Data arising from various -omics platforms such as 16S and RNA sequencing are compositional in nature. In this kind of data, correlations between features on raw counts have no meaningful interpretation. Metrics of proportionality were formulated to address this problem. However, an inherent bias arises when these metrics are calculated empirically on count-based measures due to variability in read depths. We quantify the bias introduced by empirically calculating proportionality-based association metrics in count data. Additionally, we propose a means of estimating these metrics within a logit-normal multinomial model in pursuit of more accurate estimates. The model-based estimates are shown to outperform empirical estimates in simulated data and are applied to a mouse embryonic stem cell single-cell sequencing dataset, as well as a pediatric-onset multiple sclerosis metagenomic dataset.

Animals↗
PubMed2006

The natural history of juvenile or subacute GM2 gangliosidosis: 21 new cases and literature review of 134 previously reported.

OBJECTIVE: Juvenile GM2 gangliosidosis is a group of inherited neurodegenerative diseases caused by deficiency of lysosomal beta-hexosaminidase resulting in GM2 ganglioside accumulation in brain. The purpose of this study was to delineate the natural history of the condition and identify genotype-phenotype correlations that might be helpful in predicting the course of the disease in individual patients. METHODS: A cohort of 21 patients with juvenile GM2 gangliosidosis, 15 with the Tay-Sachs variant and 6 with the Sandhoff variant, was studied prospectively in 2 centers. Our experience was compared with previously published reports on 134 patients. Information about clinical features, beta-hexosaminidase enzyme activity, and mutation analysis was collected. RESULTS: In our cohort of patients, the mean (+/-SD) age of onset of symptoms was 5.3 +/- 4.1 years, with a mean follow-up time of 8.4 years. The most common symptoms at onset were gait disturbances (66.7%), incoordination (52.4%), speech problems (28.6%), and developmental delay (28.6%). The age of onset of gait disturbances was 7.1 +/- 5.6 years. The mean time for progression to becoming wheelchair-bound was 6.2 +/- 5.5 years. The mean age of onset of speech problems was 7.0 +/- 5.6 years, with a mean time of progression to anarthria of 5.6 +/- 5.3 years. Muscle wasting (10.6 +/- 7.4 years), proximal weakness (11.1 +/- 7.7 years), and incontinence of sphincters (14.6 +/- 9.7 years) appeared later in the course of the disease. Psychiatric disturbances and neuropathy were more prevalent in patients with the Sandhoff variant than in those with the Tay-Sachs variant. However, dysphagia, sphincter incontinence, and sleep problems occurred earlier in those with the Tay-Sachs variant. Cerebellar atrophy was the most common finding on brain MRI (52.9%). The median survival time among the studied and reviewed patients was 14.5 years. The genotype-phenotype correlation revealed that in patients with the Tay-Sachs variant, the presence of R178H and R499H mutations was predictive of an early onset and rapidly progressive course. The presence of either G269S or W474C mutations was associated with a later onset of symptoms along with a more slowly progressive disease course. CONCLUSIONS: Juvenile GM2 gangliosidosis is clinically heterogeneous, not only in terms of age of onset and clinical features but also with regard to the course of the disease. In general, the earlier the onset of symptoms, the more rapidly the disease progresses. The Tay-Sachs and Sandhoff variants differed somewhat in the frequency of specific clinical characteristics. Speech deterioration progressed more rapidly than gait abnormalities in both the Tay-Sachs variant and Sandhoff variant groups. Among patients with the Tay-Sachs variant, the HEXA genotype showed a significant correlation with the clinical course.

Acute Disease↗
PubMed2005

Hidden focal EEG seizures during prolonged suppressions and high-amplitude bursts in early infantile epileptic encephalopathy.

OBJECTIVE: We report on a 27-month-old female with atypical early infantile epileptic encephalopathy (EIEE), who developed tonic spasms, partial seizures and myoclonic jerks along with episodic bradycardia at 5 days. METHODS: We recorded digital electroencephalography (EEG) using either an 11-channel neonatal montage or 19 channel scalp electrodes, at 200 Hz sampling rate, and a single reference for a minimum of 30 min. RESULTS: At 18 days EEG showed suppression-burst (SB) patterns during wakefulness and sleep. Tonic spasms concomitant with bursts recorded as brief, low-amplitude fast waves. EEG at 8 months showed increased amplitude of bursts to 1 mV and extension of suppression periods to 65 s. By increasing recording sensitivity, we detected focal epileptiform discharges of slow rhythmic sharp and slow waves building to 30 microV during suppression periods. Status epilepticus occurred at 16 months. EEG at 27 months returned to the previous SB pattern with rare partial seizures. CONCLUSIONS: This report is the first to demonstrate clinically silent focal EEG seizures during prolonged suppression periods in atypical EIEE by off-line digital EEG. SIGNIFICANCE: Digital EEG sensitivity can reveal covert electrical activity during suppression periods in epileptic neonates and infants.

Brain↗
PubMed2005

Unusual variants of Alexander's disease.

The purpose of this study was to describe unusual variants of Alexander's disease. We studied 10 patients who did not meet previously established magnetic resonance imaging (MRI) criteria for Alexander's disease, but for whom this diagnosis was considered because of Rosenthal fibers at histological examination or presence of some MRI features suggestive of Alexander's disease. Sequence analysis of the GFAP gene was performed. In eight patients, MRI results showed predominantly posterior fossa lesions, especially multiple tumor-like brainstem lesions. One patient had asymmetrical frontal white matter abnormalities and basal ganglia abnormalities. One patient (Patient 10) developed degeneration of the frontal white matter. In nine patients, a mutation was found that was concluded to be pathogenic, because the mutation was de novo (five patients), a known mutation was found (two patients), or assembly of the glial fibrillary acidic protein was abnormal in cultured cells (two patients). In Patient 10, a DNA variation was found that was also present in the patient's clinically unaffected father and was concluded to be a polymorphism. In conclusion, DNA diagnostics is warranted in patients who display MRI features suggestive of Alexander's disease, even if they do not meet the full set of previously established MRI criteria.

Adolescent↗
PubMed2005

Glial fibrillary acidic protein mutations in infantile, juvenile, and adult forms of Alexander disease.

Alexander disease is a progressive, usually fatal neurological disorder defined by the widespread and abundant presence in astrocytes of protein aggregates called Rosenthal fibers. The disease most often occurs in infants younger than 2 years and has been labeled a leukodystrophy because of an accompanying severe myelin deficit in the frontal lobes. Later onset forms have also been recognized based on the presence of abundant Rosenthal fibers. In these cases, clinical signs and pathology can be quite different from the infantile form, raising the question whether they share the same underlying cause. Recently, we and others have found pathogenic, de novo missense mutations in the glial fibrillary acidic protein gene in most infantile patients examined and in a few later onset patients. To obtain further information about the role of glial fibrillary acidic protein mutations in Alexander disease, we analyzed 41 new patients and another 3 previously described clinically, including 18 later onset patients. Our results show that dominant missense glial fibrillary acidic protein mutations account for nearly all forms of this disorder. They also significantly expand the catalog of responsible mutations, verify the value of magnetic resonance imaging diagnosis, indicate an unexpected male predominance for the juvenile form, and provide insights into phenotype-genotype relations.

Adolescent↗
PubMed2005

Treatment of children and adolescents with multiple sclerosis.

The onset of multiple sclerosis is being increasingly recognized in children and adolescents. There are now approved immunomodulatory therapies for adults with multiple sclerosis. Treatment early in the disease course appears to have a greater impact on disease outcome, an issue of particular importance for children who face decades of multiple sclerosis disease activity. This review summarizes the multiple sclerosis therapies currently available, efficacy data available from studies of these medications in adults and limited information on the use of these medications in children. Future directions in multiple sclerosis therapeutics and specific issues relating to pediatric multiple sclerosis are discussed.

Adolescent↗
PubMed2004

Epstein-Barr virus in pediatric multiple sclerosis.

CONTEXT: Infection with common viruses, particularly Epstein-Barr virus (EBV), has been postulated to contribute to the pathobiology of multiple sclerosis (MS). Detailed virological studies in pediatric MS have not been previously reported. OBJECTIVE: To evaluate whether children with MS are more likely to be seropositive for EBV or other common viruses than their healthy age-matched peers. DESIGN, SETTING, AND PATIENTS: Case-control study of viral samples collected from March 1994 to February 2003 from 30 pediatric MS patients, 90 emergency department controls matched 3:1 with the MS patients by year of birth, and 53 healthy control children. MAIN OUTCOME MEASURES: Archived serum samples were analyzed for the presence of IgG antibodies directed against EBV viral capsid antigens, nuclear antigens, and early antigens, cytomegalovirus, parvovirus B19, herpes simplex virus, and varicella zoster. RESULTS: Serological evidence for remote EBV infection was present in 83% of pediatric MS patients compared with 42% of emergency department and healthy controls (P<.001). Five pediatric MS patients were negative for all 3 EBV antigens. Pediatric MS patients were less likely than controls to have been exposed to herpes simplex virus (P =.003), while seropositivity for cytomegalovirus, parvovirus B19, and varicella zoster did not differ between MS patients and controls. CONCLUSION: These results suggest an association between EBV infection and pediatric MS.

Adolescent↗