A protein kinase homologue controls phosphorylation of ganciclovir in human cytomegalovirus-infected cells.
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Amino Acid Sequence↗
Biomedical subjects
M Davis
Publications and source records attributed to M Davis.
A protein kinase homologue controls phosphorylation of ganciclovir in human cytomegalovirus-infected cells.
Human cytomegalovirus (HCMV) is a major pathogen in immunosuppressed individuals, including patients with acquired immune deficiency syndrome. The nucleoside analogue ganciclovir (9-(1,3-dihydroxy-2-propoxymethyl)-guanine) is one of the few drugs available to treat HCMV infections, but resistant virus is a growing problem in the clinic and there is a critical need for new drugs. The study of ganciclovir-resistant mutants has indicated that the selective action of ganciclovir depends largely on virus-controlled phosphorylation in HCMV-infected cells. The enzyme(s) responsible have not been identified. Here we report that the HCMV gene UL97, whose predicted product shares regions of homology with protein kinases, guanylyl cyclase and bacterial phosphotransferases, controls phosphorylation of ganciclovir in HCMV-infected cells. A four-amino-acid deletion of UL97 in a conserved region, which in cyclic AMP-dependent protein kinase participates in substrate recognition, causes impaired ganciclovir phosphorylation. The implications of these results for antiviral drug development and drug resistance are discussed.
Amino Acid Sequence↗
Involvement of pertussis toxin sensitive G-proteins in conditioned fear-potentiated startle: possible involvement of the amygdala.
The present study evaluated the effects of intraventricular or intracerebral administration of pertussis toxin on fear-potentiated startle (a measure of conditioned fear) and shock sensitization (a measure of unconditioned fear). In Experiment 1 all animals were unilaterally implanted with cannulae into the lateral ventricle 1 week prior to 2 days of fear conditioning (ten light-shock pairings on each of 2 days). Five days later, animals were infused with either 1 microgram pertussis toxin or saline and tested for fear-potentiated startle 24 h after infusion and tested for shock sensitization 26 or 50 h after infusion. Pertussis toxin blocked the ability of a light conditioned stimulus to facilitate startle but did not alter the ability of acute footshock to increase startle amplitude in the same animals. In Experiment 2 bilateral infusion of 1 microgram pertussis toxin into the basolateral nuclei of the amygdala, but not the interpositus nuclei of the cerebellum, also blocked fear-potentiated startle when animals were tested 6 h after infusion. These findings suggest a role for pertussis toxin sensitive G-proteins, perhaps within the amygdala, in the expression of conditioned but not unconditioned fear.
Acoustic Stimulation↗
Preliminary observations of holmium:YAG laser tissue interaction using human uterus.
Preliminary observations of a pulsed Ho:YAG laser on human uterine tissue in-vitro are presented. The tissue effect on the uterine myometrium was demonstrated using fresh uteri which had been subjected to laser energy. The laser crater and surrounding zone of thermal necrosis (ZTN) was quantified. Measurements demonstrated a consistent narrow ZTN (0.8-1.8 mm) irrespective of power or pulse frequency used. The percentage forward transmission of laser energy through 1 mm of myometrium was investigated using a pyroelectric detector and found to be 0.41%. Finally, a visible and measureable photoacoustic component to the Ho:YAG laser was demonstrated using a water bath and needle hydrophone.
Biophysical Phenomena↗
The design of liposomal paramagnetic MR agents: effect of vesicle size upon the relaxivity of surface-incorporated lipophilic chelates.
The 1/T1 NMRD profiles of lipid vesicles with the paramagnetic ion Gd attached via a chelate covalently linked to the membrane surface show a peak at approximately 20 MHz indicating that fluctuations of approximately 10(-8) s contribute to the form of the dispersion profile. If the correlation time for fluctuations of the paramagnetic chelate on the membrane surface is much less than the correlation time for rotation of the lipid vesicle, it would be expected that the measured 1/T1 relaxation rate for solvent protons should be invariant with vesicle size above a certain minimum vesicle diameter. We show that this is indeed the case for vesicles in the size range 50 to 400 nm average diameter and discuss general design considerations for the preparation of vesicle-associated MR contrast agents based upon paramagnetic chelates either trapped within the vesicle interior or attached to the membrane surface.
Chelating Agents↗
Immunocytochemical demonstration of T4 content and TSH-binding by cells of the thyroid of the developing chick embryo.
The numerical densities (Nv) of immunostained thyroxine (T4)-positive cells and thyrotropin-stimulating hormone (TSH)-positive cells were determined in chick embryos on Day 5.5 through Day 11.5 and Days 5.5, 7.5, 9.5, 10.5, 11.5, 12.5, 13.5, 14.5, 15.5, 16.5, and 17.5, respectively. The data demonstrate that selected cells of the "prefollicular" thyroid contain T4 and bind TSH at least as early as Day 5.5. The Nv of immunocytochemically demonstrable T4-positive cells increases gradually from Day 5.5 to Day 10.5, exhibiting a statistically significant increase (P less than 0.05) between Day 10.5 and Day 11.5. Similarly, the Nv of TSH-binding cells (Nv TSH) rises slowly from Day 5.5 until Day 11.5, followed by a statistically significant (P less than 0.05) increase between Day 11.5 and Day 12.5. The peak Nv TSH value on Day 12.5 is followed by a decline (P less than 0.05) on Day 13.5, and from Day 14.5 through Day 17.5, Nv TSH values remain relatively constant. Changes in the Nv of T4-positive and TSH-binding cells over developmental time are discussed with regard to pituitary regulation of the chick embryo thyroid and the possible contribution of the yolk to circulating T4 levels.
Animals↗
Lesions of the central nucleus of the amygdala block the excitatory effects of septal ablation on the acoustic startle reflex.
Many studies have investigated the role of the septum and the amygdala in emotional behavior. While the literature is somewhat inconsistent, most studies suggest a role for the septal nuclei in the inhibition of fear and stress responses (at the behavioral, autonomic and hormonal levels) while the central nucleus of the amygdala is involved in the production of such responses. The present study examined the ability of lesions of the central nucleus of the amygdala to block the excitatory effects of complete septal ablation on the acoustic startle reflex. Septal ablation produced a significant increase in startle amplitude which was blocked by concomitant lesions of the central nucleus of the amygdala. These results suggest that the increase in startle amplitude resulting from septal damage might be due to a disinhibition of neuronal activity in the central nucleus of the amygdala, a structure known to mediate the increase in startle associated with conditioned and unconditioned fear, or from antagonistic interactions at other target sites which themselves modulate startle.
Acoustic Stimulation↗
The role of the amygdala in fear-potentiated startle: implications for animal models of anxiety.
Over the past several years, major advances have been made in understanding the pharmacology of anxiety, involving three broad classes of experimental approach. One approach studies the mechanism of action of drugs that are known to treat anxiety clinically, such as the benzodiazepines. A second approach uses various animal models of fear or anxiety that are sensitive to known anxiolytic drugs, to see if they will detect new compounds. A third approach involves describing the neural pathways and neurotransmitters that are active in a state of fear or anxiety; importantly, this approach is not derived from the mechanisms of known anxiolytics. In this review, Michael Davis describes such a 'neural systems' approach to the study of fear or anxiety that uses the paradigm of fear-potentiated startle.
Amygdala↗
High dose endobronchial irradiation in recurrent bronchogenic carcinoma.
Between November 1988 and March 1990, 24 patients with endobronchial tumors that had recurred after external beam radiation therapy were treated with high dose rate intraluminal irradiation. A remote afterloading high dose rate unit was used, and most patients received two endobronchial treatments, separated by a two week interval. All patients were given the same dose and dose specification to assess the feasibility and complications of the therapy. At each treatment, 15 Gy were delivered with dose specified at a radius of 6 mm from the center of the source, which corresponds to a dose of 9 Gy at a radius of 1 cm. Overall, 21 of 24 patients (88%) showed good symptomatic improvement. Of 18 patients whose chest x-ray showed evidence of collapse or atelectasis caused by tumor obstruction, 15 (83%) had evidence of reaeration. The median duration of palliation, marked by symptoms or a chest x-ray that worsened, was 26 weeks, the range varying from seven to 40 weeks. No patient died as a result of therapy and only one had a complication, bronchospasm, which responded well to bronchodilators. One patient died of hemoptysis approximately three months after treatment. Five additional patients, who were treated off protocol because they had an Eastern Cooperative Oncology Group performance status of greater than two, also received endobronchial irradiation. All five died within one month from worsening pulmonary disease, and we do not recommend endobronchial irradiation for patients with an Eastern Cooperative Oncology Group performance status of greater than two. We conclude that high dose rate endobronchial brachytherapy effectively relieves the symptoms of endobronchial obstruction due to recurrent lung cancer and can be given safely as an outpatient procedure. As the complications were minimal in this series treated with a uniform dose of 15 Gy per treatment, future studies should aim at determining the maximum tolerated dose. This technique may also be helpful as a boost after maximal external beam irradiation or to open up areas of atelectasis prior to external beam irradiation.
Adult↗
N-methyl-D-aspartate lesions of the lateral and basolateral nuclei of the amygdala block fear-potentiated startle and shock sensitization of startle.
Cell bodies in the lateral and basolateral amygdaloid nuclei were destroyed by local infusion of N-methyl-D-aspartate. Adjacent areas, such as the central amygdaloid nucleus, were largely spared. Lesions were carried out before training and testing (Experiment 1) or after training but before testing (Experiment 2). In both cases, the lesions completely blocked fear-potentiated startle (increased acoustic startle in the presence of a light previously paired with footshock). They also blocked increased startle after a series of footshocks, provided they damaged the most anterior part of the basolateral nucleus. It is suggested that the lateral or basolateral amygdaloid nuclei (or both) relay visual information to the central amygdaloid nucleus, which is also critical for fear-potentiated startle. In addition, activation of the most anterior part of the basolateral nucleus may be critical for processing shock information during fear conditioning.
Amygdala↗
Intra-amygdala infusion of the N-methyl-D-aspartate receptor antagonist AP5 blocks acquisition but not expression of fear-potentiated startle to an auditory conditioned stimulus.
The fear-potentiated startle paradigm, in which the amplitude of the startle reflex is enhanced in the presence of a stimulus previously paired with footshock, was used to measure aversive conditioning after intra-amygdala infusion of the competitive N-methyl-D-aspartate (NMDA) receptor antagonist DL-2-amino-5-phosphonopentanoic acid (AP5). Infusion of 2.5 micrograms/side AP5 immediately before five noise-footshock pairings on each of 2 consecutive days dose-dependently blocked acquisition or consolidation of auditory fear-potentiated startle, consistent with previous results from our laboratory obtained with a visual stimulus. Somatosensory or auditory transmission deficits do not appear to be induced by intra-amygdala AP5 because rats reacted normally to footshocks and showed reliable potentiated startle expression after pretesting AP5 infusion at a dose that blocked acquisition. Together with earlier reports, these data suggest that an NMDA-dependent process localized in or near the amygdala may be necessary for the acquisition of conditioned fear across different sensory modalities.
2-Amino-5-phosphonovalerate↗
The relationship between 111In-labelled immunoscintigraphy and serum CA-125 levels in ovarian carcinoma patients postchemotherapy.
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Antibodies, Monoclonal↗
A phase I-II study of recombinant intrapleural alpha interferon in malignant pleural effusions.
Malignant pleural effusion is a common and significant source of morbidity for many patients with cancer. In an attempt to control this condition without using chest tube drainage, we administered recombinant interferon alpha-2b (INTRON, Schering-Plough, Kenilworth, NJ) intrapleurally via catheter after routine thoracentesis. Twenty-two installations of interferon were administered to 15 patients in incremental dosages of 3-50 x 10(6) U/m2. Of 20 evaluable treatments, six (30%) achieved effusion stabilization; there were no complete or partial responses. Only one of nine treatments at a dosage less than 20 x 10(6) units/m2 resulted in symptoms, while four of 11 treatments at the higher dosage were associated with transient fever, chills, and chest pain. Interferon demonstrated no major activity in this heavily treated patient population with advanced malignancy.
Adult↗
A computerized CIS enhances bedside intensive care.
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Critical Care↗
The false localizing signs of increased intracranial pressure.
False localizing signs, although rare, indicate significant increased intracranial pressure with tissue shift, has occurred. A review of the historical perspective highlights the discovery of these false localizing signs, and exploration of the anatomic and physiologic causes provides important insight for neuroscience nurses. Critical thinking skills, and a world view paradigm for clinical practice are developed upon an in-depth understanding of neurologic dysfunction. Collaborative relationships are enhanced by an interdisciplinary approach to assessment of the critically ill neuroscience patient.
Brain Neoplasms↗
The anti-hepatitis B virus activities, cytotoxicities, and anabolic profiles of the (-) and (+) enantiomers of cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine.
The anti-hepatitis B (anti-HBV) activities of the (-) and (+) enantiomers of cis-5-fluoro-1-[2-(hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine (2'-deoxy-3'-thia-5-fluorocytosine [FTC]) were studied by using an HBV-transfected cell line (HepG2 derivative 2.2.15, subclone P5A). The (-) isomer was found to be a potent inhibitor of viral replication, with an apparent 50% inhibitory concentration of 10 nM, while the (+) isomer was found to be considerably less active. Both isomers showed minimal toxicity to HepG2 cells (50% inhibitory concentration, > 200 microM) and showed minimal toxicity in the human bone marrow progenitor cell assay. In accord with the cellular antiviral activity data, the 5'-triphosphate of (-)-FTC inhibited viral DNA synthesis in an endogenous HBV DNA polymerase assay, while the 5'-triphosphate of the (+) isomer was inactive. Unphosphorylated (-)-FTC did not inhibit product formation in the endogenous assay, suggesting that the antiviral activity of the compound is dependent on anabolism to the 5'-triphosphate. Both (-)- and (+)-FTC were anabolized to the corresponding 5'-triphosphates in chronically HBV-infected HepG2 cells. The rate of accumulation and the steady-state concentration of the 5'-triphosphate of (-)-FTC were greater. Also, (-)-FTC was not a substrate for cytidine deaminase and, therefore, is not subject to deamination and conversion to an inactive uridine analog. The (+) isomer is, however, a good substrate for cytidine deaminase.
Animals↗
Structured approach to the investigation of anaemia in patients with rheumatoid arthritis.
A group of 28 patients with rheumatoid arthritis who were severely anaemic were investigated for iron deficiency. On the basis of bone marrow studies, the patients were divided into two groups, those with and those without signs of stainable iron in the marrow. This grouping did not distinguish between the severity of their rheumatoid arthritis measured by clinical parameters. Measurement of the red cell count and biochemical parameters in the peripheral blood showed a statistical difference in red cell size, haemoglobin content, and iron binding capacity between the two groups. The statistical variation of these parameters, however, did not allow these measurements to predict bone marrow iron deficiency in any subject. Investigation of the upper gastrointestinal tract by endoscopy showed that acute macroscopic lesions were infrequently associated with anaemia. It was concluded that anaemia in association with rheumatoid arthritis may mimic iron deficiency anaemia, and that simple investigations of the peripheral blood do not accurately show the iron status of the reticuloendothelial system in the presence of a chronic inflammatory disease. For the investigation of severe anaemia in rheumatoid arthritis, bone marrow assessment of iron status should be performed as the initial investigation. In addition, iron deficient patients require investigation of the lower and the upper gastrointestinal tract.
Administration, Oral↗
The role of the amygdala in fear and anxiety.
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Amygdala↗