Citations

Cerebrospinal fluid (CSF) leak is recognized to cause headaches that typically but not invariably have orthostatic features (present in upright posture, relieved by recumbency). Head magnetic resonance imaging (MRI) typically shows diffuse pachymeningeal enhancement. A 24-year-old woman, after resection of a right temporoparietal glioma, developed CSF leak from the craniotomy site, resulting in subgaleal fluid collection and associated with diffuse pachymeningeal gadolinium enhancement as well as posture-related headaches. The headaches, however, were present in a recumbent position and relieved after several minutes of being in an upright position. It is postulated that CSF leak took place when the patient was recumbent and ceased when she was upright, a position in which there is decrease in intracranial pressure. After cessation of the leak, along with disappearance of subgaleal collection of CSF, both the headaches and the pachymeningeal enhancement resolved.

ABSTRACT Gene therapy in eukaryotes has met many obstacles. Research into the design of suitable nonviral vectors has been slow. To our knowledge, no nonviral vector has been proposed that allows for the possibility of highly efficient, site‐selective integration into the genome of mammalian cells. On the basis of prior studies investigating the components necessary for transposon, retrovirus‐like retrotransposon, and retroviral integration, we propose a nonviral system that would potentially allow for site‐selective, efficient integration into the mammalian genome. Transposons have been developed that can transform a variety of cell lines. For example, the Sleeping Beauty transposon (SB) can transform a wide range of vertebrate cells from fish to human, and it mediates stable integration and long‐term transgene expression in mice. However, the efficiency of transposition varies significantly among cell lines, suggesting the possible involvement of host factors in SB transposition. Here, we propose the use of a chimeric transposase (i.e., transposase‐host DNA binding domain) to bypass the potential requirement of a host DNA‐directing factor (or factors) for efficient, site‐selective integration. We also discuss another potential method of docking the transposonbased vector adjacent to the host DNA, utilizing repetitive sequences for homologous recombination to promote efficient site‐selective integration, as well as other site‐selective nonviral approaches.—Kaminski, J. M., Huber, M. R., Summers, J. B., Ward, M. B. Design of a nonviral vector for site‐selective, efficient integration into the human genome. FASEB J . 16, 1242–1247 (2002)

Mutations of c-KIT causing spontaneous activation of the KIT receptor kinase are associated with sporadic adult human mastocytosis (SAHM) and with human gastrointestinal stromal tumors. We have classified KIT-activating mutations as either “enzymatic site” type (EST) mutations, affecting the structure of the catalytic portion of the kinase, or as “regulatory” type (RT) mutations, affecting regulation of an otherwise normal catalytic site. Using COS cells expressing wild-type or mutant KIT, 2 compounds, STI571 and SU9529, inhibited wild-type and RT mutant KIT at 0.1 to 1 μM but did not significantly inhibit the Asp816Val EST mutant associated with SAHM, even at 10 μM. Using 2 subclones of the HMC1 mast cell line, which both express KIT with an identical RT mutation but which differ in that one also expresses the Asp816Val EST mutation, both compounds inhibited the RT mutant KIT, thereby suppressing proliferation and producing apoptosis in the RT mutant-only cell line. Neither compound suppressed activation of Asp816Val EST mutant KIT, and neither produced apoptosis or significantly suppressed proliferation of the cell line expressing the Asp816Val mutation. These studies suggest that currently available KIT inhibitors may be useful in treating neoplastic cells expressing KIT activated by its natural ligand or by RT activating mutations such as gastrointestinal stromal tumors but that neither compound is likely to be effective against SAHM. Furthermore, these results help establish a general paradigm whereby classification of mutations affecting oncogenic enzymes as RT or EST may be useful in predicting tumor sensitivity or resistance to inhibitory drugs.

Synthesis of Tyr in the human body occurs by hydroxylation of the indispensable amino acid Phe. Until now, it was believed that in humans, this process was restricted to the liver, but we provide compelling evidence of production of Tyr from Phe in the kidney. To determine whether the human kidney produces Tyr, we measured Tyr balance, the Tyr appearance rate, and the Phe-to-Tyr conversion in 12 healthy human subjects by using [ 15 N]Phe and [ 2 H 4 ]Tyr as tracers. Renal plasma flow was measured by using paraaminohippurate, and sampling from the femoral artery and renal veins was performed. The results were compared with those obtained in 12 control subjects undergoing hepatic vein catheterization and infusion of identical tracers. In all 12 subjects, there was a net uptake of Phe by the kidney (2.2 ± 1.2 μmol/min), whereas Tyr was released (5.3 ± 1.5 μmol/min). In contrast, there was a net uptake of both Phe (9.5 ± 1.2 μmol/min) and Tyr (14.3 ± 1.3 μmol/min) by the splanchnic bed. Phe conversion to Tyr occurred at a rate of 5.2 ± 1.2 μmol/min in kidney and 3.0 ± 0.7 μmol/min in the splanchnic bed. The kidney contributed a substantial amount of Tyr to the systemic circulation where the splanchnic bed was a net remover of Tyr. Our results demonstrate that the kidney is the major donor of Tyr to the systemic circulation by its conversion of Phe to Tyr. This observation may have important clinical implications for patients with both renal and hepatic disease, who may be at risk of Phe overloading and Tyr deficiency, and it should be considered when parenteral or enteral nutrients are administered rich in Phe and low in Tyr.

The Sp1-like family of transcription factors is emerging as an integral part of the cellular machinery involved in the control of gene expression. Members of this family of proteins contain three highly homologous C-terminal zinc-finger motifs that bind GC-rich sequences found in the promoters of a diverse number of genes, such as the basic transcription element (BTE) in the promoter of the carcinogen-metabolizing cytochrome P4501A1 (CYP1A1) gene. In the present study, we report the molecular and functional characterization of BTE-binding protein (BTEB) 4, a novel ubiquitously expressed member of the Sp1-like proteins family. This protein represents a new homologue of BTEB1, originally described as a regulator of the BTE site in the CYP1A1 gene promoter. Similarly to the recently described BTEB3, we demonstrate that the N-terminal region of BTEB4 directly represses transcription and binds the co-repressor mSin3A. In addition, we show that the C-terminal zinc-finger domain of BTEB4 binds specifically the BTE site of the CYP1A1 promoter, similar to BTEB1 and BTEB3. Also, we show that both BTEB3 and BTEB4 repress the CYP1A1 gene promoter via the BTE site in HepG2 and BxPC3 cells. Thus the identification of this protein expands the repertoire of BTEB-like members of the Sp1-like protein family involved in transcriptional repression. Furthermore, our results demonstrate that the BTEB subfamily can repress the CYP1A1 gene promoter via the BTE site.