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Biomedical subjects

E G Brown

Publications and source records attributed to E G Brown.

At least 37 records · Page 2Linked to original sources
PubMed1998

Selective use of vancomycin to prevent coagulase-negative staphylococcal nosocomial bacteremia in high risk very low birth weight infants.

OBJECTIVE: To determine whether vancomycin added to parental nutrition (PN) fluids could prevent nosocomial infections in very low birth weight newborns and which infants would benefit most from prophylaxis. DESIGN: Double blind, randomized controlled study. SETTING AND STUDY POPULATION: Very low birth weight infants receiving PN in a tertiary neonatal intensive care unit. METHODS: Thirty-eight infants with and without central vascular catheters were randomized to receive no medication or 25 microg/ml vancomycin added to PN for the duration of the infant's PN requirements. RESULTS: The addition of 25 microg/ml vancomycin to PN prevented bacteremia in very low birth weight infants receiving PN. There was a significant reduction in the number of coagulase-negative staphylococcal (CONS) bacteremias (defined as isolation of the same organism from two positive blood cultures) during PN (5 vs. 0; P = 0.037) as well as the total number of bacteremias and fungemias (9 vs. 1; P = 0.036). The total number of hospital days (108 +/- 13 vs. 76 +/- 6; P = 0.039) were reduced in infants receiving vancomycin. Infants with birth weights of < 1000 g who received corticosteroids for treatment of chronic lung disease benefitted most from treatment. No vancomycin-resistant strains of CONS or enterococci were detected during the study period. CONCLUSIONS: Prophylactic treatment with vancomycin effectively prevented CONS bacteremia under the conditions of the study. Its use was most effective in infants with birth weights of <1000 g.

Anti-Bacterial Agents↗
PubMed1998

The reovirus protein mu2, encoded by the M1 gene, is an RNA-binding protein.

The reovirus M1, L1, and L2 genes encode proteins found at each vertex of the viral core and are likely to form a structural unit involved in RNA synthesis. Genetic analyses have implicated the M1 gene in viral RNA synthesis and core nucleoside triphosphatase activity, but there have been no direct biochemical studies of mu2 function. Here, we expressed mu2 in vitro and assessed its RNA-binding activity. The expressed mu2 binds both poly(I-C)- and poly(U)-Sepharose, and binding activity is greater in Mn2+ than in Mg2+. Heterologous RNA competes for mu2 binding to reovirus RNA transcripts as effectively as homologous reovirus RNA does, providing no evidence for sequence-specific RNA binding by mu2. Protein mu2 is now the sixth reovirus protein demonstrated to have RNA-binding activity.

Baculoviridae↗
PubMed1996

Stable expression of the reovirus mu2 protein in mouse L cells complements the growth of a reovirus ts mutant with a defect in its M1 gene.

Reovirus mu2 protein was constitutively expressed in mammalian cells transfected with dicistronic constructs in which the reovirus M1 gene and the selectable neomycin-resistant gene (neo) were both driven by the same phosphoglycerate kinase promoter. Translation of neo was initiated with the cap-independent translation initiation element from encephalomyocarditis virus. Expression of mu2 protein was detected by mu2-specific antibody produced through immunization of rabbits with Trp-E-mu2 fusion proteins expressed in Escherichia coli. The expression levels of mu2 proteins of serotype 1 (T1) and serotype 3 (T3) were different and varied in different mouse cell lines with T1 being expressed more efficiently than T3. mu2 expressing L929 cell lines generated with the dicistronic constructs were highly stable. Inclusion of the transforming fragment of bovine papillomavirus in the dicistronic construct lead to higher levels of mu2 expression that were less stable and thus decreased on continued cell culture. The mu2 protein expressed in transfectants was authentic as shown by peptide mapping comparison with mu2 protein from reovirus-infected cells and that from in vitro transcription and translation of the M1 gene. It was further shown that the mu2 protein expressed in a stable L929 cell line complemented the growth of the reovirus tsH11.2 mutant with a defect in its M1 gene. It is concluded that the mu2 protein stably expressed by transfection is functionally equivalent to mu2 protein expressed by reovirus.

Animals↗
PubMed1996

Translation of the reovirus M1 gene initiates from the first AUG codon in both infected and transfected cells.

Reovirus mu 2 protein can be expressed via the mouse phosphoglycerate kinase promoter to low levels in stably transfected L cells. To increase mu 2 expression, the terminal regions of the M1 gene cDNA constructs were modified and the effect on mu 2 expression was analyzed. The M1 gene has a single large open reading frame beginning at nucleotide 14 with another, in frame, AUG codon at nucleotide 161 reported to be used for translation initiation. Unexpectedly, deletions of the M1 5' terminal sequence upstream of the reported translation initiation codon, AUG161, resulted in loss of detection of mu 2 expression. When expression was driven by the stronger T7 promoter in the presence of recombinant vaccinia virus expressing the T7 RNA polymerase, constructs with the M1 5'-terminal deletion produced a smaller protein product of approximately 68 kDa, compared to approximately 73 kDa for the protein produced from the full-length M1-containing constructs consistent with the loss of 49 amino acids. The amount of shorter mu 2 product was increased by producing an improved 'Kozak' consensus sequence around the AUG codon at nucleotide 161 or by introducing an internal ribosome entry site at this location. Full-length M1 gene constructs produced a protein of the same size as the authentic mu 2 protein from virus-infected cells. It was further shown that the approximately 73 kDa product was expressed when the M1 gene was in different plasmid backgrounds and even when the M1 gene transcript was preceded by a 1 kb gene. This study demonstrated that translation of the reovirus M1 gene initiates from the first AUG codon in both infected and transfected cells.

3T3 Cells↗
PubMed1996

Mutations in the hemagglutinin and matrix genes of a virulent influenza virus variant, A/FM/1/47-MA, control different stages in pathogenesis.

The mouse adapted strain of influenza A/FM/1/47 virus, FM-MA, has increased virulence due to mutations in HA, M1 and at least one other, unmapped, genome segment. Genetic reassortants that differ due to the HA or M1 mutations were used to define the role of these mutations in pathogenesis. Pathological changes in lungs of infected mice were assessed by hematoxylin phloxine saffron (HPS) staining, and viral infection was measured by fluorescent antibody staining of thin sections and flow cytometry of lung parenchymal cells. HA played a role in bronchiolar pathology by increasing necrosis of bronchiolar epithelium, peribronchiolar lymphocytes, and airway obstruction. The HA mutation was shown to be responsible for a 0.2 unit decreased in the pH optimum of fusion and controlled resistance to alpha and beta inhibitors of hemagglutination. Both these changes in biology may confer a replicative advantage in bronchioles seen in the first day of infection. Thus the HA mutation may have conferred a survival advantage in the extracellular lung environment. The M1 mutation resulted in improved growth in the lung and cultured cells and was associated with increases in recruitment of macrophages, spread of infection into the alveoli of the lung and interstitial pneumonia. Sequence analysis indicated that the unmapped mutation in the control of FM-MA virulence is either the K482-->R substitution in the PB2 protein or the D538-->G substitution in the PB1 protein. One or other of these mutations results in a growth advantage in infected lung but not in cultured cells as well as a further increased recruitment and infection of macrophages in the lung. Infection with virulent strains of influenza that induced increases in macrophage recruitment caused hypothermia in the mouse.

Animals↗
PubMed1996

The Urabe AM9 mumps vaccine is a mixture of viruses differing at amino acid 335 of the hemagglutinin-neuraminidase gene with one form associated with disease.

The reason for the high incidence of vaccine-associated meningitis due to the Urabe AM9 vaccine was assessed by comparing the nucleotide (nt) sequence of the hemagglutinin-neuraminidase (HN) gene from vaccine virus to those of viruses isolated from persons with postvaccination meningitis. A G1081--> A nt substitution that was predicted to result in a Glu335--> Lys reversion in the HN protein was detected between Urabe AM9 (G) and postvaccine meningitis mumps virus isolates (A). Further analysis showed that the Urabe AM9 vaccine was a mixture of viruses with wild type (A) and variant (G) nt at position 1081. Urabe AM9 vaccinees who developed meningitis or parotitis possessed predominantly A (98%-100%) at nt 1081, indicating strong selection of the wild type (A) form relative to the variant (G) form. Mumps virus homogeneous for the variant Glu335 form of the HN gene may be safer than the original Urabe AM9 vaccine.

Animals↗
PubMed1996

Thyroglossal duct cyst causing airway obstruction in an adult.

Thyroglossal duct cysts, though not uncommon, rarely present with evidence of laryngeal compromise. The case presented is one of the very few cases with documented laryngeal invasion reported in the English language. Of clinical significance is the patient's presentation with laryngeal symptoms of choking and dysphonia in the presence of a small anterior cervical mass. While the thyroglossal duct cyst usually presents as an asymptomatic anterior neck mass, this case illustrates the importance of considering a thyroglossal duct cyst in any patient with airway compromise in the absence of a neck mass.

Adult↗
PubMed1995

Augmentation of murine hematopoiesis by interleukin 2-activated irradiated T cells.

We have examined the role of T cells activated with interleukin-2 (IL-2) in vitro and subsequently irradiated (2500 rads), in stimulating murine hematopoiesis in a syngeneic system. Our data suggest that activated, irradiated T (AIT) cells significantly increased the progenitor cell activity of T cell-depleted bone marrow (BM) both in vitro and in vivo as compared with controls (P < 0.001). The efficacy of AIT cells was comparable to that of activated, nonirradiated T (AT) cells (P > 0.05). Optimal stimulation of BM progenitor cell activity was seen when T cells were activated for 4 days and used in a BM to T cell ratio of 1:2 or 1:5. The effect of these activated cells was related to the release of factors with ability to enhance hematopoiesis. These observations may have implications in enhancing the engraftment of T cell-depleted BM in allogeneic transplantation.

Animals↗
PubMed1995

Successful prenatal management of hydrops, caused by congenital cystic adenomatoid malformation, using serial aspirations.

Congenital cystic adenomatoid malformation (CCAM) is a lung lesion that is now commonly diagnosed in utero with fetal ultrasonography. The described treatment of this lesion includes observation with treatment delivery, a single aspiration, thoraco-amniotic shunts, and fetal resection. This patient had an in utero diagnosis of a Stocker type I CCAM associated with hydrops. Fetal resection was not an option because of patient refusal. The fetus was treated with multiple serial aspirations. There was marked improvement of the anasarca, and subsequently the baby was born without respiratory distress. On the second day of life the CCAM began to expand, and the right lower lobe was resected. The baby's postoperative course was uneventful. CCAM with hydrops is associated with a high mortality rate. Current recommended therapy for these lesions is fetal resection or thoracoamniotic shunt. The authors' patient was treated with serial fetal thoracocenteses, with an excellent outcome. This therapy may be an alternative to fetal surgery or an adjunct to fetal surgery in selected cases.

Adult↗
PubMed1995

Induction of antitumor effect by treatment with cyclosporine A plus interferon-gamma after chemotherapy: role of cytotoxic cells.

We have previously shown that administration of cyclosporine A (CsA) plus interferon-gamma (IFN) after chemotherapy to mice bearing B16 melanoma results in the generation of cells with major histocompatibility complex (MHC)-unrestricted cytotoxicity in vitro and in vivo; the antitumor effect of these cells could be attenuated by normal spleen cells. This study shows that antitumor effect after treatment with CsA plus IFN after chemotherapy was mediated by T and natural killer (NK) cells, both in vitro and in vivo. Infusion of purified T or NK cells into secondary recipients after chemotherapy resulted in a significant control in the dissemination of tumor as compared to chemotherapy alone. The antitumor potential of NK cells was at least 10 times greater than that of T cells. The effector cells could inhibit the proliferation of tumor cells in vitro without a contact between the effector and tumor cells, suggesting that antitumor effect in this system was partly related to the secretion of cytotoxic factors by the effector cells. Infusion of normal spleen cells inhibited the antitumor effect of adoptively transferred effector cells. This study defines the nature of effector cells involved in mediating the antitumor effect in this model; the optimal efficacy of these cells in the recipient is possibly related to the abolition of a suppressor system by chemotherapy.

Animals↗
PubMed1995

Role of granulocyte colony-stimulating factor in preventing ceftazidime-induced myelosuppression in vitro.

Ceftazidime has been reported to cause myelosuppression both in vitro and in vivo. Granulocyte colony-stimulating factor (G-CSF) is known to enhance the proliferation and differentiation of myeloid cells. The present study was carried out to define the role of G-CSF in preventing the ceftazidime-induced suppression of BM progenitor cells in vitro, and to define the mechanisms involved in ceftazidime-induced myelosuppression. Our results show that G-CSF was able to maintain the proliferative activity of BM cells in the presence of ceftazidime if it was added to the culture medium during the early phase of exposure of BM to ceftazidime. Monoclonal antibody to TNF completely inhibited the ceftazidime-induced myelosuppression. The suppressive effect on BM was mediated via CD3+ T cells whereas macrophages conferred protection against this suppression. TNF-induced suppression of BM was inhibited by G-CSF. These data suggest that G-CSF prevents the ceftazidime-induced myelosuppression by antagonizing the suppressive effect of TNF and by enhancing the proliferative activity of BM.

Bone Marrow↗
PubMed1994

Protective effect of granulocyte-colony stimulating factor against amphotericin B-induced myelosuppression in vitro.

Amphotericin B causes suppression of bone marrow (BM) progenitor cells in vitro. Granulocyte colony stimulating factor (G-CSF) enhances the proliferation of myeloid cells. The present study defines the role of G-CSF in preventing amphotericin B-induced myelosuppression. G-CSF increased the proliferative potential of BM and protected against amphotericin B-induced myelosuppression if it was added to the medium during the early phase of exposure of BM to amphotericin B. Monoclonal antibodies to tumour necrosis factor-alpha (TNF) or interferon-gamma (IFN) inhibited the myelosuppression partially; simultaneous presence of both these antibodies completely abrogated this suppression, suggesting that both TNF alpha and IFN gamma were involved in amphotericin-induced myelosuppression. TNF- or IFN-induced suppression of BM was also inhibited by G-CSF. These data suggest that G-CSF prevents the amphotericin B-induced myelosuppression by antagonizing the suppressive effects of TNF and IFN and by enhancing the proliferative activity of BM.

Amphotericin B↗
PubMed1994

The influenza virus variant A/FM/1/47-MA possesses single amino acid replacements in the hemagglutinin, controlling virulence, and in the matrix protein, controlling virulence as well as growth.

Genetic analysis of mouse-adapted influenza virus variant A/FM/1/47 (FM) MA has previously identified four genome segments, 4, 5, 7, and 8, that are statistically associated with virulence. On sequencing these genome segments, we found single amino acid replacements at amino acid 47 of the HA2 subunit of the hemagglutinin and at amino acid 139 of the matrix protein. Mutation was not detected in segments 5 and 8, obviating a role for these genes in FM-MA virulence. FM-MA replicates to higher titer than FM in MDCK cells and in mouse lung. FM X FM-MA reassortants were used to show that the M1 gene controlled replication in MDCK cells as well as in mouse lung.

Animals↗
PubMed1993

Use of polyethylene glycol-bound superoxide dismutase, polyethylene glycol-bound catalase, and nimodipine to prevent hypoxic ischemic injury to the brain of newborn pigs.

OBJECTIVE: To determine if polyethylene glycol-bound superoxide dismutase and catalase and nimodipine, alone or in combination, will ameliorate hypoxic ischemic injury to the brain. SUBJECTS: A total of 78 newborn (0 to 3 days) pigs were used. DESIGN: Prospective, blinded, randomized, controlled trial. INTERVENTIONS: The piglets were subjected to hypoxic ischemic brain injury. Carotid arteries were ligated at time 0 and BP was reduced one third by hemorrhage. At 15 mins, FIO2 was reduced to 0.6. At 30 mins, carotids were released, blood was reinfused, and FIO2 was increased to 1.0. Pigs were randomly assigned at time 35 mins to receive either: 10,000 U/kg of polyethylene glycol-bound superoxide dismutase and catalase (group 1); 0.5 mg/kg of nimodipine (group 2); both 10,000 U/kg of superoxide dismutase and catalase and 0.5 mg/kg of nimodipine (group 3); or no drugs (controls). MEASUREMENTS: The time after reoxygenation for return of electroencephalogram, respiration, blink and pain were recorded in minutes as well as a neurologic examination at 1, 2, and 3 days and pathologic examination of the brain at 3 days, both by blinded observers. MAIN RESULTS: There were no significant differences in the four groups. CONCLUSIONS: Polyethylene glycol-bound superoxide dismutase and catalase, and nimodipine, either alone or in combination, do not ameliorate hypoxic ischemic injury to the brain in the newborn pig when given 5 mins after reoxygenation.

Animals↗
PubMed1993

A novel approach to immunomodulation of frozen human bone marrow with interleukin-2 for clinical application.

Interleukin-2 (IL-2) activation of fresh or frozen bone marrow (BM) in vitro generates killer cells with potent anti-tumor effect both in vitro and in vivo. The IL-2-activated BM (ABM) retains the capacity to reconstitute the hematopoietic system in an autologous bone marrow transplantation (ABMT) setting. The killer cells lose their cytotoxicity if the ABM undergoes the procedures of freezing and thawing. Therefore, for clinical application, the ABM has to be generated after thawing a frozen stock of BM before ABMT. The thawed BM cells are fragile and may undergo lysis, resulting in clump formation and cell loss. The frozen autograft also contains components of cryoprotectant mixture whose effects on the generation of ABM have not been defined. The present studies have been carried out to optimize a technique of handling the frozen BM for immunomodulation with IL-2 for 24 h at 37 degrees C prior to ABMT, with minimal loss of cells. IL-2-activation of BM was carried out in bags containing serum free medium which were designed to permit gaseous exchange. Addition of deoxyribonuclease (DNAse) (100 micrograms/ml of BM concentrate) immediately after thawing and the presence of heparin (20 units/ml) in the medium completely abrogated immediate or delayed clumping of cells. The presence of DNAse and/or heparin during in vitro culture did not affect the cell viability, cytotoxicity against tumor cells or the progenitor cell activity of the ABM; all these functions were well maintained even when BM was placed in culture immediately after thawing (without washing). There was no microbial contamination.(ABSTRACT TRUNCATED AT 250 WORDS)

Bone Marrow↗