Genetically regulated aryl hydrocarbon hydroxylase induction in the eye: possible significance of the drug-metabolizing enzyme system for the retinal pigmented epithelium-choroid.

Aryl hydrocarbon (benzo[a]pyrene) hydroxylase induction in the eye from inbred C57BL/6N (responsive) and DBA/2N (nonresponsive) mice and from offspring of the appropriate genetic crosses was investigated. The hydroxylase activity is two- to more than 10-fold inducible in the eye by intraperitoneally administered polycyclic hydrocarbons such as β-naphthoflavone, 3-methylcholanthrene, and 2,3,7,8-tetrachlorodibenzo-p-dioxin and is apparently under the same genetic regulation as that in liver. Histofluorescent examination of the eye from β-naphthoflavone-treated C57BL/6N mice indicates that the hydroxylase activity is closely associated with the retinal pigmented epithelium-choroid layer; the retina demonstrates little activity. It is proposed that genetically controlled induction of the hydroxylase activity and perhaps other cytochrome P-450-mediated mono-oxygenase activities in the retinal pigmented epithelium-choroid play an important role for detoxification and/or metabolic potentiation of drugs and other xenobiotics. These foreign compounds, which include drugs, insecticides, and chemical carcinogens, presumably enter the retina through the choriocapillaris.     

Direct mapping of beta-adrenergic receptors in the rat central nervous system by a novel fluorescent beta-blocker.

DL-N-(2-Hydroxy-3-napthyloxypropyl)-N'-dansylethylenediamine, dansyl analogue of propranolol (DAPN) is a novel fluorescent beta-adrenergic antagonist with high affinity to beta-receptors. The distribution pattern of DAPN fluorescence was studied in the rat central nervous system subsequent to its intravenous administration to living rats. DAPN distinctly labels specific regions and cells in the central nervous system (CNS). Highly dense DAPN fluorescence was observed in the pyramidal cell layer of the hippocampus, the granule cell layer of the dentate gyrus, the basal layers of the piriform cortex and the neocortex, the cerebellar Purkinje cell layer, and the spinal a-motoneurons. Pretreatment of control rats with DL-and L-propranolol markedly decreased the intensity and density of DAPN fluorescence in the tissue sections, whereas prior administration of D-propranolol had almost no effect. Pretreatment with large doses of reserpine did not alter the pattern of DAPN fluorescence. These findings were identical to those observed with another fluorescent beta-blocker, 9-aminoacridino-propranolol (9-AAP). Our data suggest that fluorescent beta-adrenergic antagonists may be used in vivo for the direct probing of the beta-receptors within the mammalian CNS.     

Direct mapping of β-adrenergic receptors in the rat central nervous system by a novel fluorescent β-blocker

dl-N-(2-Hydroxy-3-napthyloxypropyl)-N′-dansylethylenediamine, dansyl analogue of propranolol (DAPN) is a novel fluorescent β-adrenergic antagonist with high affinity to β-receptors. The distribution pattern of DAPN fluorescence was studied in the rat central nervous system subsequent to its intravenous administration to living rats. DAPN distinctly labels specific regions and cells in the central nervous system (CNS). Highly dense DAPN fluorescence was observed in the pyramidal cell layer of the hippocampus, the granule cell layerof the dentate gyrus, the basal layers of the piriform cortex and the neocortex, the cerebellar Purkinje cell layer, and the spinal α-motoneurons. Pretreatment of control rats withdl- andl-propranolol markedly decreased the intensity and density of DAPN fluoresence in the tissue sections, whereas prior administration ofd-propranolol had almost no effect. Pretreatment with large doses of reserpine did not alter the pattern of DAPN fluorescence. These findings were identical to those observed with another fluorescent β-blocker, 9-aminoacridino-propranolol (9-AAP). Our data suggest that fluorescent β-adrenergic antagonists may be used in vivo for the direct probing of the β-receptors within the mammalian CNS.     

Randomized trial of high-dose methylprednisolone versus intravenous immunoglobulin for the treatment of acute idiopathic thrombocytopenic purpura in children

BACKGROUND: Idiopathic thrombocytopenic purpura (ITP) is an acquired disorder characterized by immune-mediated platelet destruction. The authors performed a prospective, randomized trial comparing intravenous immunoglobulin (IVIG) with high-dose intravenous methylprednisolone in the treatment of children with acute ITP. The primary aim of the study was to compare the rate of platelet increase produced by either intervention. A decision to treat was based on the clinical presentation and not an arbitrary platelet count. In general, enrolled patients exhibited extensive bruising and platelet counts less than 10 x 10 /L (10,000/microL). PATIENTS AND METHODS: Seventy-seven consecutive patients, for whom the attending hematologist determined acute treatment was warranted, were studied. Forty-two patients received IVIG (1 g/kg/dose x2) and 35 received methylprednisolone (30 mg/kg/dose x3). Patients who exhibited an increase in platelet count of more than 50,000/microL after the first IVIG dose or the second methylprednisolone dose did not receive the second IVIG dose or the third methylprednisolone dose, respectively. Patients' ages ranged from 6 months to 15 years. Platelet counts were evaluated at presentation, 24, 48, 72 hours, 1 week, and 2 to 4 weeks. RESULTS: Eighty percent of patients treated with IVIG and 60% of patients treated with methylprednisolone demonstrated an increase in platelet count of 50,000/microL or more within 48 hours. Both IVIG and methylprednisolone therapy increased platelet counts significantly above pretreatment values. In the methylprednisolone group, the mean baseline platelet count was 4,600/microL, which rose to 14,000/microL after 24 hours, 38,000/microL after 48 hours, and 65,000/microL after 72 hours. The IVIG group had a mean baseline platelet count of 4,200/microL, which rose to 32,000/microL after 24 hours, 69,000/microL after 48 hours, and 146,000/microL after 72 hours. When compared with methylprednisolone, IVIG therapy produced a greater rise in platelet counts at 24, 48, and 72 hours, with no difference at 1 week or later time points. No serious bleeding was noted in either treatment group. CONCLUSIONS: Both IVIG and methylprednisolone produce a significant early rise in platelet count that is somewhat greater with IVIG. However, the higher platelet counts produced by IVIG may not justify the additional cost and potential risks of this agent.     

Gray matter N-acetyl aspartate deficits in secondary progressive but not relapsing-remitting multiple sclerosis

BACKGROUND AND PURPOSE: Spectroscopic examination of multiple sclerosis (MS) patients has revealed abnormally low N-acetyl-aspartate (NAA) signal intensity, even in brain tissue that appears normal on high-resolution structural MR images but has yielded inconclusive evidence to distinguish the well-documented clinical differences between MS subtypes. This study used proton MR spectroscopic imaging (MRSI) and high-resolution MR imaging to characterize metabolite profiles in normal-appearing brain tissue of relapsing-remitting multiple sclerosis (RRMS) and secondary progressive (SP) MS. METHODS: Volumetric spiral MRSI was used together with high-resolution MR imaging to derive absolute measures of metabolite concentrations separately in normal-appearing supratentorial cerebral gray matter and white matter in five RRMS patients, five SPMS patients, and nine age-matched controls. Structural MR images were segmented into compartments of gray matter, white matter, CSF, and lesions, and metabolite signals per unit of tissue volume were calculated for gray matter and white matter separately. RESULTS: Only the SPMS group had significantly lower NAA concentrations in normal-appearing gray matter compared with concentrations in controls. NAA in normal-appearing white matter was equally reduced in RRMS and SPMS patients. The functional relevance of this brain metabolite measure was suggested by the observed but statistically nonsignificant correlation between higher disability scores on the Expanded Disability Status Scale and lower gray matter NAA concentrations. CONCLUSION: The otherwise occult abnormality in supratentorial gray matter in SPMS but not RRMS may explain the more severe physical and cognitive impairments afflicting patients with SPMS that do not correlate well with visible lesion burden.     

Line scan diffusion imaging of the spine

BACKGROUND AND PURPOSE: Recent findings suggest that diffusion-weighted imaging might be an important adjunct to the diagnostic workup of disease processes in the spine, but physiological motion and the challenging magnetic environment make it difficult to perform reliable quantitative diffusion measurements. Multi-section line scan diffusion imaging of the spine was implemented and evaluated to provide quantitative diffusion measurements of vertebral bodies and intervertebral disks. METHODS: Line scan diffusion imaging of 12 healthy study participants and three patients with benign vertebral compression fractures was performed to assess the potential of line scan diffusion imaging of the spinal column. In a subgroup of six participants, multiple b-value (5-3005 s/mm(2)) images were obtained to test for multi-exponential signal decay. RESULTS: All images were diagnostic and of high quality. Mean diffusion values were (230 +/- 83) x 10(-6) mm(2)/s in the vertebral bodies, (1645 +/- 213) x 10(-6) mm(2)/s in the nuclei pulposi, (837 +/- 318) x 10(-6) mm(2)/s in the annuli fibrosi and ranged from 1019 x 10(-6) mm(2)/s to 1972 x 10(-6) mm(2)/s in benign compression fractures. The mean relative intra-participant variation of mean diffusivity among different vertebral segments (T10-L5) was 2.97%, whereas the relative difference in mean diffusivity among participants was 7.41% (P <.0001). The estimated measurement precision was <2%. A bi-exponential diffusion attenuation was found only in vertebral bodies. CONCLUSION: Line scan diffusion imaging is a robust and reliable method for imaging the spinal column. It does not suffer as strongly from susceptibility artifacts as does echo-planar imaging and is less susceptible to patient motion than are other multi-shot techniques. The different contributions from the water and fat fractions need to be considered in diffusion-weighted imaging of the vertebral bodies.     

A deletion mutant of heregulin increases the sensitivity of breast cancer cells to chemotherapy without promoting tumorigenicity

Heregulin (HRG) is an activator of the erbB2-, erbB3- and erbB4-(erbB-2/3/4) signaling pathway. Transfection of full-length HRG cDNA into the estrogen (E2)-dependent cell line MCF-7 promoted an invasive E2-independent phenotype, as well as persistent activation of the erbB-2/3/4 receptors. Moreover, HRG expression in MCF-7 cells renders the cells sensitive to the topoisomerase II inhibitor doxorubicin (Doxo). In an attempt to dissociate the tumorigenic effect of HRG from the sensitizing effect to chemotherapy, we constructed a structural deletion mutant of HRG. Transfection of the deletion mutant of HRG described in this study (HRG/M) into MCF-7 cells resulted in the dissociation of the tumor-promoting activity of HRG from the sensitization to Doxo, that is, although the cells did not become more aggressive or E2-independent they became more sensitive to Doxo. HRG/M was unable to autophosphorylate the erbB receptors and did not affect the level of MAPK phosphorylation. Furthermore, the intracellular localization of the protein was different from that of the full-length protein. Our data show that the HRG/M sequences are sufficient to sensitize MCF-7 cells to Doxo, and provide evidence that this sensitization is independent of erbB2 activation.     

Black cohosh, a menopausal remedy, does not have estrogenic activity and does not promote breast cancer cell growth

Black cohosh is an increasingly popular alternative to estrogen replacement therapy for the relief of menopausal symptoms, primarily hot flushes. However, an important consideration for long-term therapy is potential toxicity and carcinogenicity. Therefore, we undertook a study to assess the estrogenic activity of black cohosh to examine its safety for those with, or at high risk of developing, breast cancer. Several assays were utilized as listed: RNAse protection assays, which ascertain the regulation of the expression of E2-responsive genes; estrogen-responsive-element (ERE)-luciferase, which determines modulation of the ER function by transactivation of the ERE; the Ishikawa cell system, which has an E2-regulated endogenous alkaline phosphatase; and colony formation of ER-expressing breast cancer cells, which indicates possible progression of early stage breast cancer into a more aggressive state. Black cohosh extracts did not demonstrate estrogenic activity in any of these assay systems. This is an encouraging step in the assessment of the safety of black cohosh for treatment of menopausal hot flushes.