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Biomedical subjects

R Newman

Publications and source records attributed to R Newman.

At least 19 recordsLinked to original sources
PubMed2000

Biochemical analyses of the AF10 protein: the extended LAP/PHD-finger mediates oligomerisation.

Leukaemogenesis correlates with alterations in chromatin structure brought about by the gain or loss of interactive domains from regulatory factors that are disrupted by chromosomal translocations. The gene MLL, a target of such translocation events, forms chimaeric fusion products with a variety of partner genes. While MLL appears to be involved in chromatin-mediated gene regulation, the functions of its partner genes are largely speculative. We report the biochemical analysis of the MLL partner gene AF10 and its possible role in leukaemogenesis. AF10 has been reported to be re-arranged with genes other than MLL leading to the same phenotype, a myeloid leukaemia. We have identified a novel protein-protein interaction motif in the AF10 protein comprising the extended LAP/PHD-finger. This domain mediates homo-oligomerisation of recombinant AF10 and is conserved in several proteins, including MLL itself. AF10 binds cruciform DNA via a specific interaction with an AT-hook motif and is localised to the nucleus by a defined bipartite nuclear localisation signal in the N-terminal region.

Amino Acid Motifs↗
PubMed2000

Elimination of Fc receptor-dependent effector functions of a modified IgG4 monoclonal antibody to human CD4.

Several CD4 mAbs have entered the clinic for the treatment of autoimmune diseases or transplant rejection. Most of these mAbs caused CD4 cell depletion, and some were murine mAbs which were further hampered by human anti-mouse Ab responses. To obviate these concerns, a primatized CD4 mAb, clenoliximab, was generated by fusing the V domains of a cynomolgus macaque mAb to human constant regions. The heavy chain constant region is a modified IgG4 containing two single residue substitutions designed to ablate residual Fc receptor binding activity and to stabilize heavy chain dimer formation. This study compares and contrasts the in vitro properties of clenoliximab with its matched IgG1 derivative, keliximab, which shares the same variable regions. Both mAbs show potent inhibition of in vitro T cell responses, lack of binding to complement component C1q, and inability to mediate complement-dependent cytotoxicity. However, clenoliximab shows markedly reduced binding to Fc receptors and therefore does not mediate Ab-dependent cell-mediated cytotoxicity or modulation/loss of CD4 from the surface of T cells, except in the presence of rheumatoid factor or activated monocytes. Thus, clenoliximab retains the key immunomodulatory attributes of keliximab without the liability of strong Fcgamma receptor binding. In initial clinical trials, these properties have translated to a reduced incidence of CD4+ T cell depletion.

Animals↗
PubMed2000

Chimeric human-simian anti-CD4 antibodies form crystalline high symmetry particles.

A chimeric human-simian IgG, antigen specific for CD4, when exposed to 0.5 M SO(=)(4) containing 0.4% polyethylene glycol or Jeffamine, self-assembles into discreet, roughly spherical particles 23 nm in diameter. Increasing SO(=)(4) to 1.55 M induces the IgG particles to crystallize in either a hexagonal or a monoclinic form. From X-ray diffraction, the former crystal is of space group P622, with one IgG particle in the unit cell; thus the particle itself must have 622 point group symmetry. Both crystal forms have been imaged using atomic force microscopy. Detailed features of the duodecamer were evident, including the symmetry and a large solvent channel along the sixfold axis. The particles in some ways resemble the hexameric IgG aggregates believed to activate compliment upon antigen binding and, therefore, may have physiological relevance. Investigation of seven other IgGs of diverse origins and subclasses indicates that many, if not most, IgGs form similar particles. To our knowledge, this is the first observation of the assembly of IgG into high symmetry aggregates in the absence of antigen or their crystallization.

Animals↗
PubMed2000

Reported adoption of dietary fat and fiber recommendations among consumers.

OBJECTIVE: To identify constraints in adopting dietary fat and fiber recommendations. DESIGN: A questionnaire was mailed to a sample of the general population, a convenience sample of persons with heart disease and cancer in 11 states, and registered dietitians in 5 states. The survey included questions on demographic and attitudinal factors that were correlated with specific practices to reduce fat intake and increase fiber intake. SETTING: From the general population sample of 6,206 eligible respondents (return rate of 51.5%), those selected were respondents who indicated that they would adopt a dietary recommendation if it were good for them (n = 2,682). Subsamples from the general population were matched to 362 registered dietitians and 147 persons with cancer or heart disease on selected demographic variables. Factors associated with adoption of specific behaviors were identified. STATISTICAL ANALYSIS PERFORMED: Statistical analysis included chi 2, factor analysis, and analysis of variance. RESULTS: The majority of persons who said they would adopt a fat-reducing behavior if it were good for their health reported practicing that behavior often or usually. More than 60% reported consuming whole grains; however, only 15% reported eating fruits and vegetables frequently. Among the general population sample, those more likely to practice a behavior had the following characteristics: female, college educated, older than 60 years, white, higher income, no children younger than 18 years, perceived health status as excellent, and absence of chronic disease. Registered dietitians and those with chronic disease were also more likely to follow dietary fat and fiber recommendations. APPLICATIONS: Nutrition education messages that lead to increased consumption of dietary fiber need to be developed. Nutrition educators should provide strategies for consumers for increasing use of fruits and vegetables in all meals. Good taste and convenience are critical components. The food industry may assist by providing a wider array of convenience entrees or side dishes that feature produce and whole grains.

Adult↗
PubMed2000

Measurement of protein interaction bioenergetics: application to structural variants of anti-sCD4 antibody.

This chapter has described a bioenergetic analysis of the interaction of sCD4 with an IgG1 and two IgG4 derivatives of an anti-sCD4 MAb. The MAbs have identical VH and VL domains but differ markedly in their CH and CL domains, raising the question of whether their antigen-binding chemistries are altered. We find the sCD4-binding kinetics and thermodynamics of the MAbs are indistinguishable, which indicates rigorously that the molecular details of the binding interactions are the same. We also showed the importance of using multiple biophysical methods to define the binding model before the bioenergetics can be appropriately interpreted. Analysis of the binding thermodynamics and kinetics suggests conformational changes that might be coupled to sCD4 binding by these MAbs are small or absent.

Antibodies, Monoclonal↗
PubMed2000

Selenium and immunocompetence in patients with head and neck cancer.

This randomized double-blind placebo-controlled study aimed to determine whether oral intake of 200 microg/d of sodium selenite, a dose within the safe and adequate daily intake (50-200 microg/d) recommended by the U.S. Food and Nutrition Board, will abrogate depressed or enhance normal-level immune functions of patients receiving therapy for squamous cell carcinoma of the head and neck. Subjects were given one selenium/placebo tablet/d for 8 wk, beginning on the day of their first treatment for the disease (e.g., surgery, radiation, or surgery and radiation) and their immune functions were monitored. Supplementation with selenium (Se) during therapy resulted in a significantly enhanced cell-mediated immunue responsiveness, as reflected in the ability of the patient's lymphocytes to respond to stimulation with mitogen, to generate cytotoxic lymphocytes, and to destroy tumor cells. The enhanced responsiveness was evident during therapy and following conclusion of therapy. In contrast, patients in the placebo arm of the study showed a decline in immune responsiveness during therapy, which was followed, in some patients, by an enhancement, but the responses of the group remained significantly lower than baseline values. The data also show that at baseline, patients entered in the study had significantly lower plasma Se levels than healthy individuals, and patients in stage I or II of disease had significantly higher plasma selenium levels than patients in stage III or IV of disease.

Adult↗
PubMed1999

An NSF function distinct from ATPase-dependent SNARE disassembly is essential for Golgi membrane fusion.

The precise biochemical role of N-ethylmaleimide-sensitive factor (NSF) in membrane fusion mediated by SNARE proteins is unclear. To provide further insight into the function of NSF, we have introduced a mutation into mammalian NSF that, in Drosophila dNSF-1, leads to temperature-sensitive neuroparalysis. This mutation is like the comatose mutation and renders the mammalian NSF temperature sensitive for fusion of postmitotic Golgi vesicles and tubules into intact cisternae. Unexpectedly, at the temperature that is permissive for membrane fusion, this mutant NSF binds to, but cannot disassemble, SNARE complexes and exhibits almost no ATPase activity. A well-charaterized NSF mutant containing an inactivating point mutation in the catalytic site of its ATPase domain is equally active in the Golgi-reassembly assay. These data indicate that the need for NSF during postmitotic Golgi membrane fusion may be distinct from its ATPase-dependent ability to break up SNARE pairs.

Adenosine Triphosphatases↗
PubMed1999

Managing unstable angina and coronary care beds effectively.

This article is an evaluation of a new chest pain admission policy at Western Hospital. Our aim was to determine the clinical outcomes of patients with unstable angina treated according to this new policy. It involved attempting to identify a group at low risk of serious complications and to manage them in a general ward area without cardiac monitoring, to reduce the pressure on coronary care unit beds. We conducted a retrospective case note review and concluded that that selected patients with an admission diagnosis of unstable angina can be safely managed in unmonitored medical beds provided mechanisms are in place for their transfer to the coronary care unit if recurrent pain or a complication occurs.

Angina, Unstable↗
PubMed1999

Two neutralizing human anti-RSV antibodies: cloning, expression, and characterization.

BACKGROUND: Respiratory syncytial virus (RSV) infection is a major problem in the newborn and aging populations. Fully human monoclonal antibodies with the ability to neutralize RSV could have a major impact on the immunotherapy of the disease. The generation of human antibodies has been difficult because there exists no general way to activate B cells against an antigen of choice in vitro. MATERIALS AND METHODS: Human spleen cells from individuals exposed to RSV were used to repopulate SCID mice. Hu-SCID mice were boosted with RSV fusion (F)-protein and subsequently developed B cell tumors. The tumors were removed and cultured and subcloned in vitro, using a feeder layer of CD154-expressing T cells. Two of these tumors produced the antibodies designated RF-1 and RF-2. VL genes were isolated by standard PCR techniques, however, it was necessary to use high-temperature reverse transcriptase to clone the VH genes. RESULTS: RF-1 and RF-2 VH genes were both found to be closely related members of the VH2 family. Vk genes originated from the VK III family. RF-1 and RF-2 recombinant antibodies expressed in CHO cells (cRF-1 and cRF-2) were found to have affinities for RSV F-protein of 0.1 nM and 0.07 nM, respectively, and both were able to neutralize several A and B subtypes of RSV. CONCLUSION: The technique of immortalizing human B lymphocytes, by passage in SCID mice and expression as recombinant antibodies in CHO cells, provides a method by which high-affinity human antibodies can be developed for immunotherapy of viral diseases.

Aged↗
PubMed1999

A novel approach to monitoring adherence to preventive therapy for tuberculosis in adolescence.

OBJECTIVES: To evaluate the usefulness of a microelectronic tablet-dispenser for monitoring adherence to preventive therapy for tuberculosis infection in adolescents. METHODOLOGY: Twenty-one patients with positive Mantoux tests were treated with isoniazid (INH), dispensed in a microelectronic tablet-dispenser that recorded the date, time and duration that the container was opened. Other measures of adherence included attendance at clinic, patient self-report, tablet count, and measurement of urinary INH metabolites. RESULTS: The mean adherence rates were: 83% using attendance at clinic, 91% using tablet counts, 79% using urine assays, and 66% using the electronic tablet-dispenser. Self-reporting appeared to over-estimate adherence. CONCLUSION: Adherence to 6 months of INH calculated using different measures is higher in this study than in previous reports. Microelectronic tablet-dispensers are an effective method to objectively measure adherence on a daily basis. Other measures are less helpful.

Adolescent↗
PubMed1999

Examining the obstructed ureter with intraluminal sonography.

PURPOSE: Intraluminal sonography was used to define, differentiate and direct better treatment of obstructing ureteral lesions. MATERIALS AND METHODS: A total of 63 patients with a history of ureteral obstruction and suspected stricture were accrued for evaluation. All patients underwent retrograde contrast imaging, ureteroscopy and intraluminal sonography as part of a diagnostic algorithm. Specific sonographic criteria to differentiate lesions and stricture types were developed. Associated complicating variables defined on sonography included foreign bodies, submucosal stone fragments, ureteral wall fibrosis, mass lesions and adjacent vasculature. Endoscopic treatment was then performed with ultrasound guidance if technically feasible. RESULTS: A total of 63 ureters were evaluated with the preoperative diagnosis of ureteral stricture disease. All ureters were narrowed on contrast imaging in the segment where a stricture was suspected. On sonography 24 ureters (36%) had wall fibrosis with normal periureteral tissues. In general these strictures did well with endoscopic incision. Of the 67 ureters 13 (19%) were thickened or had edematous walls with normal architecture and without fibrosis. These patients all did well with expectant therapy. In contrast, 7 ureters (10%) were obstructed by segmental retroperitoneal fibrosis which did not respond to minimally invasive therapies. In addition, 8 ureters (12%) were obstructed by ureteral wall scarring and periureteral fibrosis, and required open surgical intervention. Ten ureteral strictures had adjacent vasculature, and endoscopic incisions under ultrasound guidance were directed safely away from these structures without associated morbidity. Calculi, stone fragments and foreign bodies embedded in the ureteral wall with associated inflammation were defined with sonography and responded to endoscopic therapies. The intraluminal sonographic diagnosis of ureteral endometriosis was made in 6 patients with a range of lesions from bright, hyperechoic blood filled cysts to an inhomogeneous fluid filled scar involving the wall and periureteral tissues. Primary ureteral carcinoma was also demonstrated in 2 patients after other diagnostic techniques failed. In 1 of these patients intraluminal sonography directed biopsies diagnosed submucosal tumor. Finally, 1 patient had a small periureteral urinoma on intraluminal sonography which was missed on other imaging studies. CONCLUSIONS: Intraluminal sonography is useful in patients with ureteral obstruction of unclear etiology as well as for selecting patients who may benefit from minimally invasive therapies and safely directing these treatments.

Adolescent↗
PubMed1998

Syntaxin 5 is a common component of the NSF- and p97-mediated reassembly pathways of Golgi cisternae from mitotic Golgi fragments in vitro.

A cell-free system that mimics the reassembly of Golgi stacks at the end of mitosis requires two ATPases, NSF and p97, to rebuild Golgi cisternae. Morphological studies now show that alpha-SNAP, a component of the NSF pathway, can inhibit the p97 pathway, whereas p47, a component of the p97 pathway, can inhibit the NSF pathway. Anti-syntaxin 5 antibodies and a soluble, recombinant syntaxin 5 inhibited both pathways, suggesting that this t-SNARE is a common component. Biochemical studies confirmed this, showing that p47 binds directly to syntaxin 5 and competes for binding with alpha-SNAP. p47 also mediates the binding of p97 to syntaxin 5 and so plays an analogous role to alpha-SNAP, which mediates the binding of NSF.

Adenosine Triphosphatases↗
PubMed1998

Clinical issues surrounding the use of terbutaline sulfate for preterm labor.

beta-mimetics have been prescribed by physicians to arrest or prevent premature labor for more than 20 years. Although not approved by the Food and Drug Administration (FDA) for tocolytic use, terbutaline sulfate has been the most widely prescribed beta-mimetic in the United States. Recently, the role of terbutaline in the treatment and prevention of preterm labor has been questioned by the FDA. Because the off-label use of drugs is a formally accepted practice in medicine when scientific studies support such use, we reviewed the currently available clinical literature on terbutaline use in various routes of delivery: intravenous, oral, and subcutaneous via infusion pump. This review describes the clinical evidence that supports the safe and effective use of terbutaline as a tocolytic agent in certain patient populations. Practicing physicians should continue to have unrestricted use of terbutaline for tocolysis as one of the few remaining therapeutic options remaining in the fight against preterm birth.

Administration, Oral↗
PubMed1997

p47 is a cofactor for p97-mediated membrane fusion.

At least two distinct ATPases, NSF and p97, are known to be involved in the heterotypic fusion of transport vesicles with their target membranes and the homotypic fusion of membrane compartments. The NSF-mediated fusion pathway is the best characterized, many of the components having been identified and their functions analysed. In contrast, none of the accessory proteins for the p97-mediated fusion pathway has been identified. Now we have identified the first such component, a protein of relative molecular mass 47,000 (p47), which forms a tight, stoichiometric complex with cytosolic p97 (one trimer of p47 per hexamer of p97). It is essential for the p97-mediated regrowth of Golgi cisternae from mitotic Golgi fragments, a process restricted to animal cells. As a homologue of p47 exists in budding yeast, this indicates that it might also be involved in other membrane fusion reactions catalysed by p97, such as karyogamy.

Adenosine Triphosphatases↗