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Biomedical subjects

J W Henson

Publications and source records attributed to J W Henson.

29 records · Page 2Linked to original sources
PubMed1996

Regional subacute cranial neuropathies following internal carotid cisplatin infusion.

The inferolateral trunk arises from the internal carotid artery at C-4 and provides vascular supply to cranial nerves III to VI. We report a patient who developed neuropathies of cranial nerves III, V1-3, and VI, 48 hours after infusion of cisplatin into the right internal carotid artery for an anaplastic oligoastrocytoma. The clinical and radiographic findings implicated direct toxicity to nerves in the distribution of the inferolateral trunk. We found additional cases by review of published brain tumor chemotherapy trials, thus identifying a novel, toxic neurovascular mechanism for injury to cranial nerves III to VI.

Adult↗
PubMed1995

Cell-specific activation of the glial-specific JC virus early promoter by large T antigen.

JC virus causes the human demyelinating disease progressive multifocal leukoencephalopathy by selective infection of glial cells. This cell specificity results from glial-specific expression of viral early genes (large and small T antigens). Analysis of transcriptional regulation by the MH1 JC virus early promoter demonstrates that glial specificity is directed by the basal promoter. Because T antigen regulates the basal region of several viral and cellular promoters, we investigated whether it controls the JC virus basal promoter in a glial-specific manner. A JC virus T antigen expression plasmid generated a 95-kDa protein which exhibited nuclear localization and physical association with p53. T antigen repressed the JC virus and SV40 early promoters 4- to 5-fold in glioma cells. Conversely, T antigen induced 100- to 200-fold activation of the JC virus early promoter in nonglial cells, whereas the SV40 promoter was repressed. Activation required the JC virus TATA box sequence and a pentanucleotide repeat immediately upstream of the TATA box, but was independent of the upstream enhancer region. These data demonstrate that the JC virus basal promoter is responsible for glial-specific gene expression and suggest a mechanism for this regulation.

Antigens, Polyomavirus Transforming↗
PubMed1995

Human gliomas with wild-type p53 express bcl-2.

Human astrocytomas frequently overexpress wild-type p53, which suggests that gliomas have evolved a mechanism to subvert p53-mediated apoptosis. bcl-2 inhibits apoptosis mediated by p53, and it is expressed in several human cancers. We therefore examined a series of human gliomas to determine whether bcl-2 is expressed and whether this expression is associated with tumors which have wild-type p53. Twenty-eight paraffin-embedded gliomas (3 WHO grade II, 13 grade III, 12 grade IV) were immunohistochemically stained for bcl-2 and p53. p53 mutations were identified with single strand conformation polymorphism and DNA sequencing. Sixteen of 28 (57%) tumors expressed bcl-2, and bcl-2 expression was associated with wild-type p53 (P < 0.01). Among gliomas which overexpressed p53, bcl-2 was positive in 7 of 7 tumors with wild-type p53 but in only 1 of 7 with mutant p53 (P < 0.01). We conclude that bcl-2 is frequently expressed in human gliomas and that expression is more common in tumors with wild-type p53.

Apoptosis↗
PubMed1994

Regulation of the glial-specific JC virus early promoter by the transcription factor Sp1.

The regulation of glial-specific JC virus early gene expression was addressed by functional dissection of a previously uncharacterized form of the JC virus promoter (MH-1). The MH-1 promoter directed 31-fold higher reporter gene expression in U87MG glioma cells than in HeLa cells in a transient transfection assay. Transfection of promoter constructs containing proximal or proximal plus upstream regions revealed that reporter gene expression was activated by both proximal and tandem repeat regions in glioma cells. The proximal region contains a guanine-rich sequence, the GA box, which was found to regulate the promoter, and was recognized specifically by the transcription factor Sp1. The GA box is also present in the promoters of three glial-specific cellular genes. Together with paired AP-1 and NF-1 sites in the tandem repeats, the GA box is part of a motif that is conserved between several glial-specific promoters, and is thus a potential determinant of glial-specific gene expression. These results delineate the promoter regions required for activation of the MH-1 JC virus promoter, suggest a new determinant of glial specificity, and establish a model for the investigation of combinatorial activation of a glial-specific viral promoter.

Base Sequence↗
PubMed1994

In situ polymerase chain reaction demonstration of JC virus in progressive multifocal leukoencephalopathy, including an index case.

Progressive multifocal leukoencephalopathy (PML) is a demyelinating disease that is caused by JC papovavirus. The virus can be demonstrated in brains with PML using a variety of techniques. In situ polymerase chain reaction (PCR) is a new method that combines the sensitivity of PCR with the histological localization of in situ hybridization. We here show that in situ PCR can detect JC virus in archival tissue sections of 3 cases of PML, including 1 of the original cases described in 1958 and 1 case that was fixed in formalin for 7 weeks. JC virus DNA was amplified directly on tissue and demonstrated in the characteristic enlarged oligodendrocytes and bizarre astrocytes. These data illustrate the utility of the in situ PCR technique in detecting JC virus in archival sections, including those fixed for prolonged periods, and provide a historical footnote to the original report of PML.

Adult↗
PubMed1994

The retinoblastoma gene is involved in malignant progression of astrocytomas.

Loss of chromosome 13q occurs in up to 50% of human astrocytomas, suggesting the presence of an astrocytoma tumor suppressor gene on that chromosome. To determine whether the retinoblastoma susceptibility gene (Rb) on 13q14 contributes to the formation of astrocytomas, we examined 85 tumors for loss of heterozygosity (LOH) at the intragenic Rb 1.20 locus. LOH was detected in 16 of 54 informative high-grade astrocytomas (30%), but was not detected in 12 low-grade gliomas. Deletion mapping with flanking markers on 13q revealed that the Rb 1.20 region was preferentially targeted by the deletions. Tumors with LOH at Rb 1.20 were examined for mutations in the remaining Rb allele using single-strand conformational polymorphism (SSCP) analysis and direct DNA sequencing. Mutations were detected in exon 8 (1 tumor), exon 24 (2 tumors), and intron 24 (1 tumor). Rb protein expression, as assessed by immunohistochemistry, was altered in 3 of 9 cases with LOH and in 1 tumor without LOH. Our results demonstrate that Rb inactivation contributes to the formation of high-grade astrocytomas, and therefore implicate a second, known tumor suppressor gene in astrocytoma tumorigenesis.

Astrocytoma↗
PubMed1992

P-glycoprotein expression in brain tumors.

Overexpression of P-glycoprotein (P-gp) in cancer cells can result in resistance to several chemotherapy agents (multidrug resistance) including doxorubicin and vincristine. The drugs to which resistance develops also penetrate the blood brain barrier poorly. P-gp expression in brain capillary endothelial cells suggests that P-gp may restrict drug entry into brain tumors and thus be another mechanism of drug resistance. To seek evidence for either of these roles in the drug resistance of brain tumors, we examined the location of expression of P-gp in 49 brain tumors, using an anti-P-gp mouse monoclonal antibody and immunohistochemistry. P-gp expression was observed in tumor cells of two glioblastomas and a meningeal sarcoma but not in low-grade primary or metastatic tumors. In low-grade primary tumors, P-gp was present in all vascular endothelial cells. In the vascular endothelial cells of anaplastic primary brain tumors and brain metastases, P-gp expression was heterogeneous or absent. These findings are consistent with a role for P-gp in the resistance of some brain tumors to chemotherapy agents.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1991

Pneumocystis carinii pneumonia in patients with primary brain tumors.

All histologically documented episodes of Pneumocystis carinii pneumonia in adult patients with primary brain tumors treated at Memorial Sloan-Kettering Cancer Center, New York, NY, since 1981, were retrospectively reviewed. Pneumocystis carinii pneumonia was histologically documented 11 times in 10 patients. During the same 8-year interval, approximately 587 adults were seen at the center for a brain tumor, 90% of whom received ongoing therapy. Therefore, in at least 1.7% (10/587) of our patients with brain tumors, P carinii pneumonia developed. The median duration of dexamethasone therapy at the onset of P carinii pneumonia symptoms was 2.75 months. Symptoms began during tapering of steroid therapy in eight episodes. Bronchoscopy was diagnostic in the eight cases in which it was performed. Four episodes (40%) were fatal. Trimethoprim-sulfamethoxazole prophylaxis may be indicated in some patients with brain tumors, especially during tapering of steroid therapy.

Adult↗
PubMed1989

CNS chloromas in patients presenting with eosinophilia.

A patient presented with hypereosinophilia for 3 years followed by acute leukemia with intracranial chloroma. Eight of 15 reported cases of myeloproliferative disorder accompanied by hypereosinophilia developed meningeal chloromas, suggesting a previously unrecognized association between eosinophilia, acute leukemia, and CNS chloroma.

Adult↗
PubMed1983

An intravascular protein osmometer.

Our purpose was to develop an intravascular osmometer for measuring the colloid (i.e., protein) osmotic pressure (COP) of circulating blood. A semipermeable hollow fiber from a Cordis Dow artificial kidney (C-DAK 4000) was attached to polyethylene tubing on one end, filled with saline, and sealed at the other end. This was small enough to be inserted into the vasculature of research animals. Protein osmotic pressure plus hydrostatic pressure was measured by a Statham pressure transducer attached to the hollow fiber. Simultaneously, a second catheter and transducer was used to measure hydrostatic pressure, which was subtracted from the pressure measured from the fiber with an on-line computer. The system was documented by a variety of tests. The colloid osmotic pressure vs. albumin concentration curve determined with the fiber is identical to the curve determined by standard membrane osmometry. The time constant for 2- and 8-cm fibers was 2.6 +/- 0.6 and 1.5 +/- 0.5 (+/- SD) min, respectively. The reflection coefficient (+/- SD) of the fiber for NaCl is 0.042 +/- 0.019 (n = 38); COP measured at varying temperatures (absolute scale) changed linearly as expected from COP = nCRT (i.e., van't Hoff's law). Finally, hollow-fiber osmometers were inserted into femoral veins of dogs and sheep, and blood COP was continuously recorded during osmotic manipulations. In conclusion, we attempted to develop and document a simple method for continuous measurement of intravascular colloid osmotic pressure.

Animals↗