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Biomedical subjects

John Freeman

Publications and source records attributed to John Freeman.

5 recordsLinked to original sources

The ketogenic diet: from molecular mechanisms to clinical effects.

Recent years have witnessed an increased interest from pediatric neurologists, neuropediatricians, epileptologists and general neurologists in the use of the ketogenic diet (KD) for the management of refractory epilepsies, particularly in children and adolescents. This article summarizes current knowledge on various issues related to its use, as discussed at a recent international workshop. Aspects discussed in some detail include (i) the putative mechanisms responsible for the diet's anticonvulsant effects,based on results of biochemical and neurophysiological studies in experimental models; (ii) consensus and controversies on the modalities of initiation of the diet, and different protocols of implementation; (iii) indications and contraindications; (iv) efficacy data, also in relation to seizure type, syndromic form and patients age; (v) adverse effects; (vi) methodological aspects related to assessment of the diet's clinical effects, and perspectives for future research. Overall, the data reviewed indicate that considerable advances have been made in understanding the modes of action of the diet, its efficacy and tolerability profiles and its potential role in different types of epilepsy. Although clinical studies performed to date have important methodological limitations, including suboptimally characterized patients' populations and an uncontrolled design, a number of innovative, prospective randomized study protocols have been recently proposed and are being implemented. The results of these will hopefully provide much needed high-quality information to better define the role of the diet in the treatment algorithms in different epilepsy syndromes.

Adolescent↗

Gastric duplication cyst causing gastric outlet obstruction.

We report a rare case of gastric outlet obstruction in a newborn infant caused by a gastric duplication cyst. Ultrasound provided a non-invasive and conclusive diagnostic technique, which should be used as a baseline investigation for cases of suspected gastric outlet obstruction.

Choristoma↗

MGView: an alignment and visualization tool to enhance gap closure of microbial genomes.

Gap closure is a challenging phase in microbial random shotgun genome sequencing projects, particularly since genome assemblies are often complicated by the presence of repeat elements, insertion sequences and other similar factors that contribute to sequence misassemblies. While it is well recognized that the conservation of genetic information between microbial genomes, combined with the exponential increase in available microbial sequences, can be exploited to increase the efficiency of gap closure, we lack the computational tools to aid in this process. We describe here a new tool, MGView, which was developed to create a graphical depiction of the alignment of a set of microbial contigs against a completed microbial genome. The results of our assembly of the Staphylococcus aureus RF122 genome show that MGView enables a considerable reduction in time and economic cost associated with closure. Together, the results also show that the application of MGView not only enables a reduction in fold-coverage requirements of the random shotgun sequence phase, but also provides interesting insights into differences in gene content and organization between finished and unfinished microbial genomes.

Base Sequence↗

Auditory processing studied prospectively in two hemidecorticectomy patients.

Auditory processing of speech and nonspeech sounds was studied prospectively in two hemidecorticectomy patients (ages 10-11 years) with Rasmussen's syndrome. We tested auditory word recognition under four listening conditions: in quiet, in noise, after acoustic filtering, and dichotically. Recognition of environmental sounds and discrimination of tones and digitized syllables were also tested. Presurgical testing confirmed normal processing of speech and nonspeech, for both patients, under all listening conditon. One year after surgery, both patients demonstrated intact recognition of words and environmental sounds in quiet but impaired word recognition in noise. The left hemidecorticectomy patient also demonstrated impaired recognition of low-pass filtered words. These findings suggest that either hemisphere can process speech or nonspeech sounds in quiet, whereas both hemispheres are needed to process speech in background noise. Hemispheric contributions to processing speech in noise appear to differ, with the left hemisphere compensating for loss of phonologic information and the right hemisphere compensating for increased attention demands.

Acoustic Stimulation↗

Adeno-associated virus protects the retinoblastoma family of proteins from adenoviral-induced functional inactivation.

Adeno-associated virus type 2 (AAV) is known to inhibit virally mediated oncogenic transformation. One of the early events of adenovirus (Ad) infection is the functional inactivation of cell cycle regulatory retinoblastoma (RB) family of proteins, which consists of retinoblastoma protein (pRB), p107, and p130. In an effort to understand the molecular basis of anti-oncogenic properties of AAV, we studied the effects of AAV expression on these proteins in cells infected with Ad. Western blot analysis showed that AAV interferes with the adenoviral-induced degradation and hyperphosphorylation of the pRB family of proteins in normal human fibroblasts as well as in HeLa and 293 cell lines. RNase protection assay showed enhanced expression of pocket protein gene by AAV expression. We also demonstrate that Rep proteins, the major AAV regulatory proteins, bind to E1A, the immediate early gene of Ad responsible for hyperphosphorylation and dissociation of pRB-E2F complex. This binding of AAV Rep proteins to E1A leads to decreased association between E1A and pRB leading to protection of pocket proteins from degradation, decreased expression of S phase genes and inhibition of cell cycle progression. These results suggest that the antiproliferative activity of AAV against Ad is mediated, at least in part, by effects of AAV Rep proteins on the Rb family of proteins.

Adenovirus E1A Proteins↗