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Biomedical subjects

R Lucas

Publications and source records attributed to R Lucas.

At least 73 records · Page 4Linked to original sources
PubMed1997

Modulation of soluble and membrane-bound TNF-induced phenotypic and functional changes of human brain microvascular endothelial cells by recombinant TNF binding protein I.

In this study, the effects of TNF binding protein I (TBP I) on TNF-induced changes of human brain microvascular endothelial cells (MVEC) were investigated. TBP I completely abolished TNF-induced IL-6 production and E-selectin induction, while it partially inhibited TNF-induced IL-8 production and up-regulation of ICAM-1 and VCAM-1. Moreover, TBP I significantly inhibited TNF-induced cytotoxicity and leukocyte adherence on human brain MVEC. The inhibitory activity of TBP I for TNF was dose-dependent and related to the time of administration after TNF stimulation. In addition, TBP I inhibited membrane-bound TNF induced activation of human brain MVEC, but the concentration required was about 10-fold higher than that for soluble TNF. These results indicate a therapeutic potential for TBP I in diseases of the central nervous system associated with TNF overproduction.

Brain↗
PubMed1997

Maritime medicine.

This article reviews the emergency care of sick and injured patients on various seafaring vessels in remote areas of the world. It addresses the characteristic problems encountered by those at sea, the logistical difficulties of assessing and treating these patients on the vessel, and the difficulty in arranging and monitoring definitive care.

Case Management↗
PubMed1997

Generation of a mouse tumor necrosis factor mutant with antiperitonitis and desensitization activities comparable to those of the wild type but with reduced systemic toxicity.

In this study, we investigated whether the recently identified lectin-like domain of tumor necrosis factor (TNF) is implicated in its biological activities on mammalian cells. To this end, a mouse TNF (mTNF) triple mutant, T104A-E106A-E109A mTNF (referred to hereafter as triple mTNF), lacking the lectin-like affinity of mTNF for specific oligosaccharides, was compared with the wild-type molecule for various TNF effects in vitro and in vivo. The triple mTNF displayed a 50-fold-reduced TNF receptor 2 (TNFR2)-mediated bioactivity but only a 5-fold-reduced TNFR1-mediated bioactivity in vitro. The specific activity of the triple mutant on L929 fibrosarcoma cells was slightly reduced compared with that of the wild type. We subsequently assessed the systemic toxicity of triple versus wild-type mTNF, since TNFR2 is partially implicated in this activity. The triple mTNF had a significantly reduced toxicity compared with that of wild-type mTNF in vivo. Moreover, we compared the effects of the triple and the wild-type mTNFs in TNFR1-mediated phenomena, such as (i) induction of tolerance towards a lethal mTNF dose and (ii) protective activity in cecal ligation and puncture-induced septic peritonitis. No significant differences between the mutant and wild-type forms were observed. In conclusion, these results indicate that triple mTNF, lacking TNF's lectin-like binding capacity, has reduced systemic toxicity but retains the tolerance-inducing and peritonitis-protective activities of wild-type mTNF.

Animals↗
PubMed1997

T1a and T1b breast cancer: a twelve-year experience.

To understand the prevalence of axillary node metastasis and survival of patients with T1a and T1b breast cancers, we reviewed the experience at a large community hospital. All patients in the William Beaumont Hospital tumor registry with breast cancer treated between January 1983 and November 1995 were evaluated for tumor size, age, cell type, and the presence or absence of axillary node disease. Long-term survival was evaluated in patients treated between 1983 and 1992. The patients were defined as premenopausal or postmenopausal based on age (49 years or less, premenopausal; 50 years or greater, postmenopausal). Of the 4590 patients treated for breast cancer from 1983 to 1995, 915 had tumors 1.0 cm or less in size. Of 181 patients who had T1a cancer, 27 were premenopausal, and 154 were postmenopausal. Twenty-three premenopausal patients had axillary lymph nodes examined, two (8.7%) had histologically positive lymph nodes. Of 118 postmenopausal patients who had axillary nodes examined, six (5.1%) had positive lymph nodes. In those with T1b tumors, 130 patients were premenopausal; 604 patients were postmenopausal. Of these, 119 premenopausal patients had axillary nodes examined, and 29 (24.4%) had positive lymph nodes. Of 464 postmenopausal patients who had axillary nodes examined, 66 (14.2%) had positive nodes. The overall, disease-free, and tumor-specific survival rates for patients with T1a tumors were 93.8, 87.5, and 93.8 per cent (premenopausal) and 86.2, 95.4, and 95.4 per cent (postmenopausal), respectively. These survival rates for patients with T1b tumors were 87.8, 87.8, and 91.1 per cent (premenopausal) and 82.9, 88.5, and 92.9 per cent (postmenopausal), respectively. Premenopausal T1b patients had a higher rate of nodal involvement than postmenopausal T1b patients (P = 0.011). Postmenopausal T1b patients had a higher nodal metastasis rate than postmenopausal T1a patients (P = 0.01). T1b patients had a higher rate of axillary involvement than did T1a patients (P = 0.0018). Based on the rate of axillary lymph node metastasis and survival statistics, there may be a role for axillary node dissection in select patients with tumors less than 1.0 cm. in size.

Adult↗
PubMed1997

Nonoperative management of adult blunt splenic trauma: a 15-year experience.

From January 1989 to December 1993, 40 consecutive adult patients with ruptured spleen from blunt trauma were examined. Fourteen patients (35%) were taken to the operating room initially because of hemodynamic instability and generalized peritoneal signs. Twenty-six patients (65%) were hemodynamically stabilized at admission and treated by nonoperative management, which included strict bed rest, intensive care unit monitoring, frequent physical examinations, and serial hematocrits. Four patients failed nonsurgical management and required a splenectomy, three because of clinical deterioration within 1 to 3 days of admission; the fourth patient had recurrent bleeding 7 days after injury. The patients in the operative group had a greater severity of injury with a mean injury severity score of 26.6, four deaths, and mean transfusion requirements of 3.7 to 4.0 units of blood, compared to a mean injury severity score of 14.6, one late death from cardiac causes, and average blood requirement of 0.4 to 0.7 units. Splenic injury grading averaged 3.2 in the surgical group (grade 1, one patient; grade 2, four patients; grade 3, eight patients; grade 4, no patients; and grade 5, one patient) and differed significantly from that of the nonoperative group (mean = 2.4; grade 1, 12 patients; grade 2, seven patients; grade 3, six patients; grade 4, two patients; and grade 5, no patients). Recent ultrasound analysis of select grades I to IV has shown excellent resolution or repair of these injuries. This report extends our series from 1978 to 1993 and includes 144 adult patients sustaining blunt splenic ruptures. Seventy-nine (55%) of these patients were treated nonsurgically. Seven patients (of 80) failed nonoperative management and required interval laparotomy, representing a 91 per cent success rate. Follow-up on more than 90 per cent of the patients has shown no sequelae from their splenic injuries. We conclude that adult patients with splenic injuries from blunt trauma who are hemodynamically stable and are without abdominal findings requiring celiotomy can be safely managed by a nonoperative approach.

Adolescent↗
PubMed1997

The selective muscarinic agonist xanomeline improves both the cognitive deficits and behavioral symptoms of Alzheimer disease.

The therapeutic effects of selective cholinergic replacement using oral xanomeline, an m1/m4 receptor agonist, were assessed in a multicenter study of 343 patients with Alzheimer disease (AD). Patients were randomized to parallel treatment arms (placebo, 25, 50, and 75 mg t.i.d. xanomeline) and followed through 6 months of double-blind therapy and 1 month of single-blind placebo washout. Completer analysis, using the cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog), revealed a significant treatment effect (75 mg t.i.d. vs. placebo; p = 0.045). Similar assessment of global status, using the Clinician's Interview-Based Impression of Change, was also significant (75 mg t.i.d. vs. placebo; p = 0.022). Treatment Emergent Signs and Symptoms analysis of the Alzheimer's Disease Symptomatology Scale, revealed highly significant (p < or = 0.002) dose-dependent reductions in vocal outbursts, suspiciousness, delusions, agitation, and hallucinations. On end-point analysis, the Nurses' Observational Scale for Geriatric Patients also showed a significant dose-response relationship (p = 0.018). The improvement in ADAS-Cog provides the first clinical evidence of involvement of the m1 muscarinic receptor in cognition. Furthermore, the favorable effects of xanomeline on disturbing behaviors suggest a novel approach for treatment of the noncognitive symptoms of AD. Although adverse effects (mainly gastrointestinal) associated with the oral formulation appear to limit its use, a large-scale study investigating the safety and efficacy of transdermal xanomeline is under way.

Administration, Oral↗
PubMed1996

Transforming growth factor beta 1: three-dimensional structure in solution and comparison with the X-ray structure of transforming growth factor beta 2.

The three-dimensional solution structure of human transforming growth factor beta 1 (TGF-beta 1) has been determined using multinuclear magnetic resonance spectroscopy and a hybrid distance geometry/ simulated annealing algorithm. It represents one of the first examples of a mammalian protein structure that has been solved by isotopic labeling of the protein in a eukaryotic cell line and multinuclear NMR spectroscopy. The solution structure of the 25 kDa disulfide-linked TGF-beta 1 homodimer was calculated from over 3200 distance and dihedral angle restraints. The final ensemble of 33 accepted structures had no NOE or dihedral angle violations greater than 0.30 A and 5.0 degrees, respectively. The RMSD of backbone atoms for the ensemble of 33 structures relative to their mean structure was 1.1 A when all residues were used in the alignment and 0.7 A when loop regions were omitted. The solution structure of TGF-beta 1 follows two independently determined crystal structures of TGF-beta 2 (Daopin et al., 1992, 1993; Schlunegger & Grütter, 1992, 1993), providing the first opportunity to examine structural differences between the two isoforms at the molecular level. Although the structures are very similar, with an RMSD in backbone atom positions of 1.4 A when loop regions are omitted in the alignment and 1.9 A when all residues are considered, there are several notable differences in structure and flexibility which may be related to function. The clearest example of these is in the beta-turn from residues 69-72: the turn type found in the solution structure of TGF-beta 1 falls into the category of type II, whereas that present in the X-ray crystal structure of TGF-beta 2 is more consistent with a type I turn conformation. This may be of functional significance as studies using TGF-beta chimeras and deletion mutants indicate that this portion of the molecule may be important in receptor binding.

Amides↗
PubMed1996

Phenotypic and functional analysis of pulmonary microvascular endothelial cells from patients with acute respiratory distress syndrome.

The purpose of this study was to assess the phenotypic and functional characteristics of pulmonary microvascular endothelial cells (MVEC) in the acute respiratory distress syndrome (ARDS). Pulmonary MVEC were isolated from the lungs of five patients who developed ARDS, and from four patients who had undergone a lobectomy for lung carcinoma, as controls. Adhesion molecules and other surface molecules were quantitated on these cells by flow cytometry and the cytokines IL-6 and IL-8 were measured in the supernatants by ELISA. The constitutive expression of intercellular adhesion molecule and, to a lesser extent, vascular adhesion molecule-1, was significantly increased on MVEC isolated from all ARDS patients, as compared with control MVEC. CD14 and TNF receptor p75 were also increased on the surface of MVEC isolated from most patients with ARDS. The expression of ELAM-1 and TNF receptor p55 (TNF-R1) was not significant on the surface of either ARDS-derived or control pulmonary MVEC. The constitutive ability of ARDS-derived MVEC to secrete IL-6 and IL-8 was markedly enhanced as compared with control MVEC. Upon in vitro restimulation by TNF, pulmonary MVEC from ARDS patients showed lower ICAM-1 upregulation, but similar IL-6 and IL-8 production capacity, when compared with control MVEC. Selective differences were found in cell adhesion molecules and TNF receptor p75 expression on pulmonary MVEC isolated from patients with ARDS. These pulmonary MVEC spontaneously overexpress some adhesion molecules and produce greater amounts of the pro- and anti-inflammatory cytokines IL-8 and IL-6. These findings suggest that ICAM-1 and TNF receptor p75 may have a particular involvement in the pathogenesis of acute lung injury, and that the endothelium may be an important source of cytokines detected in broncho-alveolar lavage during this syndrome. It is tempting to hypothesize that the differences observed result from either a genetic predisposition to ARDS based on MVEC phenotype or to a long-lived MVEC phenotypic change induced by ARDS. By allowing the monitoring of phenotypic and functional parameters, cultures of pulmonary MVEC isolated from ARDS patients may thus represent a useful system to analyze further the mechanisms of acute lung injury and to evaluate the efficacy of drugs, including inhibitors of cytokines and of adhesion molecules.

Adult↗
PubMed1996

Expression and release of tumor necrosis factor-alpha by explants of mouse cornea.

PURPOSE: To elucidate a possible target of immunosuppressive agents widely used in the treatment of corneal disorders, the authors determined whether corneal cells are capable of expressing and releasing tumor necrosis factor-alpha (TNF alpha) on lipopolysaccharide (LPS) stimulation, and they investigated whether TNF alpha production can be modulated by pharmacologic agents. METHODS: Trephined central corneas from C57BL/6 mice were kept in culture for 3 days. Release of TNF alpha after a 24-hour stimulation with LPS (1 microgram/ml) into the culture medium was determined both by bioassay and by enzyme-linked immunosorbent assay. Expression of TNF alpha mRNA after 6-hour stimulation was examined by polymerase chain reaction. Immunofluorescent staining on cryostat sections of cultured corneas was performed to localize TNF alpha in the tissue. Corneal explants were pretreated with immunosuppressive agents (prednisolone, budesonide, cyclosporin A) for 48 hours, followed by 6-or 24-hour stimulation with LPS in the continuous presence of the agents. RESULTS: Lipopolysaccharide stimulated TNF alpha release into the culture medium. The addition of budesonide (10(-7) M) or prednisolone (10(-6) M) significantly inhibited LPS-induced TNF alpha release, whereas cyclosporin A (10(-7) - 10(-5) M) had no marked effect. Levels of TNF alpha mRNA in corneal explants increased fivefold after stimulation with LPS. Immunohistochemical staining revealed that TNF alpha was expressed in the epithelial cells. Budesonide markedly decreased mRNA expression and abolished immunostaining of TNF alpha stimulated by LPS. CONCLUSIONS: TNF alpha is produced and released by the epithelial cells of mouse central cornea in response to LPS. Contrary to cyclosporin A, corticosteroids such as prednisolone and budesonide potently inhibit TNF alpha production.

Animals↗
PubMed1996

[The value of ultrasonographic monitoring in mandibular lengthening using the Ilizarov principle. Preliminary results].

From a review of the literature and a clinical case, we demonstrate the value of ultrasonographic monitoring of mandibular distraction according to the Ilizarov's protocol. Unlike X rays, sonography offers early and reliable pictures of the ossification process. The ultrasonic image matches the histological aspect obtained in the course of experiment. A more accurate monitoring of the regenerating area is thus made possible.

Bone Lengthening↗
PubMed1995

Transgenic mice expressing high levels of soluble TNF-R1 fusion protein are protected from lethal septic shock and cerebral malaria, and are highly sensitive to Listeria monocytogenes and Leishmania major infections.

Mice bearing a transgene coding for a soluble tumor necrosis factor receptor type 1 (TNFR1)-FcIgG3 fusion protein and placed under the control of the alpha-1-antitrypsin gene promoter were generated. Depending on the mouse line, blood levels of the protein ranged from 25 ng/ml to over 100 micrograms/ml; this level of expression was most often transmitted to the transgene-bearing progeny as a relatively stable feature. High-expressor mice were completely resistant to lipopolysaccharide-induced shock and lethality, including after D-galactosamine sensitization, and mice expressing about 1 microgram of the fusion protein/ml were partially (60%) protected. In contrast, mice expressing less than 0.1 microgram of the protein/ml were more sensitive than controls with respect to incidence and time of death, even though the biological activity of serum tumor necrosis factor (TNF) was partially neutralized. High-expressor mice of the adequate genetic background were markedly, although not completely, protected from death by cerebral malaria after injection with Plasmodium berghei. They were highly susceptible to Listeria monocytogenes, dying from bacterial dissemination after sublethal infection, and to Leishmania major, displaying severe, non-healing lesions after local infection. Under the same conditions, mice expressing about 1 microgram protein/ml were only partially sensitive to these last agents, compared to non-transgenic littermate mice which were fully resistant. These transgenic mice represent a model of permanent, complete or partial, impairment of TNF use, which compares favorably, for ease of breeding and for the range of effects, to mice bearing gene disruptions.

Animals↗
PubMed1995

Characterization of recombinant soluble human transforming growth factor-beta receptor type II (rhTGF-beta sRII).

Recombinant human transforming growth factor soluble receptor Type II (rhTGF-beta sRII) corresponding to the 159 amino acid extracellular domain of hTGF-beta RII has been expressed in insect cells using the baculovirus expression system or in a mouse myeloma cell line. N-terminal sequence analysis of the purified protein revealed the removal of the 23 amino acid signal peptide. In SDS-PAGE, the rhTGF-beta sRII resolves into multiple bands due to N-linked glycosylation. Recombinant hTGF-beta sRII is a TGF-beta antagonist and will inhibit the biological activities of TGF-beta 1, TGF-beta 3, and TGF-beta 5 on TGF-beta-responsive cell lines, such as murine HT-2 or human TF-1 with an ED50 of approximately 0.3 micrograms/mL. However, hTGF-beta sRII does not inhibit TGF-beta 2 bioactivities in these cell lines, suggesting that hTGF-beta RII has low affinity for TGF-beta 2. Polyclonal antibodies to hTGF-beta sRII have been produced in goats and purified on Protein-G affinity columns. This antibody can inhibit TGF-beta 1,2,3,5-dependent bioactivities on human cell lines such as TF-1. Additionally, this antibody has species cross-reactivity and will also inhibit TGF-beta-dependent bioactivities on murine cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Identification of a cytolytic protein in the coelomic fluid of Eisenia foetida earthworms.

Total coelomic fluid of earthworms Eisenia foetida (Oligochaeta, Annelida) is capable of lysing different mammalian tumor cell lines. This cytolytic activity is different from tumor necrosis factor (TNF)-mediated lysis and is not due to proteolysis. Total coelomic fluid was subjected to ion-exchange chromatography separation and a fraction with prominent cytolytic activity was used to elicit monoclonal antibodies that were screened for their capacity to neutralize the cytolytic effect of total coelomic fluid. One of the prepared neutralizing IgG antibodies was used for the immunoaffinity purification of a cytolytic factor from total coelomic fluid. SDS-PAGE and Western blot analyses revealed a protein band with an apparent molecular weight of 42 kDa. This cytolytic protein (termed CCF-1 or coelomic cytolytic factor 1) can be adsorbed on the surface of opsonized particles and may be involved in opsonizing and hemolytic effects of coelomic fluid.

Animals↗
PubMed1995

The cachexia associated with Trypanosoma cruzi acute infection in mice is attenuated by anti-TNF-alpha, but not by anti-IL-6 or anti-IFN-gamma antibodies.

BALB/c male mice acutely infected with Trypanosoma cruzi underwent a severe weight loss (around 20%, from day 18 to 31 post-infection), when compared to age-matched uninfected animals. Though mice regained weight later, when blood parasites were hardly detectable, wasting extended over the chronic phase of infection. The onset and the magnitude of weight loss were related to the mouse susceptibility to infection, since they were respectively earlier and higher in male mice which will die than in surviving ones, in males than in females, and in BALB/c than in B6D2 [(C57B1/6 x DBA/2)F1], a mouse strain more resistant to infection. Fat weight of infected mice (male BALB/c) was reduced by 60 to 80%, whereas lean mass was unaffected and water content rose by 6 to 10% in acute and chronic infection. Haematocrit was also decreased by 15-16% in acute infection. Animals failed to compensate their energetic loss since their food intake remained similar to that of uninfected animals. Injections of neutralizing anti-TNF-alpha monoclonal antibody into infected male mice, during the first two weeks but not later in infection, significantly attenuated the weight loss. Early administration of anti-IL-6 or anti-IFN-gamma MoAbs did not improve the mouse wasting. Taken together, these data show that TNF is a key agent of cachexia occurring in the acute T. cruzi infection in mice.

Animals↗
PubMed1995

High tumor necrosis factor alpha (TNF-alpha) production in Trypanosoma cruzi-infected pregnant mice and increased TNF-alpha gene transcription in their offspring.

Since tumor necrosis factor alpha (TNF-alpha) is known to be involved in the feto-maternal relationship, this cytokine was studied in Trypanosoma cruzi-infected pregnant BALB/c mice and their fetuses and offspring. Pregnant chronically infected mice displayed significantly higher levels of circulating TNF-alpha than animals either only infected or only pregnant. TNF-alpha was undetectable in sera of uninfected and nonpregnant mice as well as in breast milk obtained from infected and uninfected animals. Fetuses from infected mice exhibited significantly more cells containing TNF-alpha mRNA in their thymus than fetuses from uninfected mothers. When infected 2 months after birth, offspring born to infected and uninfected mothers displayed similar amounts of circulating TNF-alpha during chronic infection, whereas this cytokine was only weakly detectable during the acute phase of the disease. An intravenous injection of lipopolysaccharide during acute infection strongly increased the production of TNF-alpha in offspring born to infected mothers to levels higher than those in progeny from uninfected mice. These results suggest that TNF-alpha is an important cytokine in the feto-maternal relationship during T. cruzi infection and that fetuses and offspring of infected mothers are primed to produce elevated levels of TNF-alpha.

Animals↗
PubMed1994

Mapping the lectin-like activity of tumor necrosis factor.

Tumor necrosis factor (TNF), but not lymphotoxin (LT), is directly trypanolytic for salivarian trypanosomes. This activity was not blocked by soluble 55-kilodalton and 75-kilodalton TNF receptors, but was potently inhibited by N,N'-diacetylchitobiose, an oligosaccharide that binds TNF. Comparative sequence analysis of TNF and LT localized the trypanocidal region, and synthetic peptides were trypanolytic. TNF molecules in which the trypanocidal region was mutated or deleted retained tumoricidal activity. Thus, trypanosome-TNF interactions occur via a TNF domain, probably with lectin-like affinity, which is functionally and spatially distinct from the mammalian TNF receptor binding sites.

Amino Acid Sequence↗