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Biomedical subjects

C Richard

Publications and source records attributed to C Richard.

At least 181 records · Page 10Linked to original sources
PubMed1993

Comparative study of a collagen corneal shield and a subconjunctival injection at the end of cataract surgery.

To compare the effectiveness of subconjunctival injections and collagen shields in delivering anti-inflammatory agents and antibiotics after cataract surgery, we conducted a prospective study of 61 patients. They were randomly assigned to three groups: subconjunctival injection of gentamicin and dexamethasone; the same route plus a collagen shield without drug; collagen shield soaked in gentamicin and dexamethasone. All subjects had a manual extracapsular cataract extraction with posterior chamber intraocular lens implantation. Eyes were evaluated at the end of surgery and 24 hours later. The collagen shield achieved a progressive effect on pain and a decrease in conjunctival redness after 24 hours. The occurrence of folds in Descemet's membrane was less frequent and aqueous flare less severe than when subconjunctival injections were used. No adverse effect was reported. We conclude that the collagen shield could be a safe, better, noninvasive technique because of its double action of bandage and enhancement of drug penetration.

Aged↗
PubMed1993

Cardiac index vs oxygen-derived parameters for rational use of dobutamine in patients with congestive heart failure.

In patients with congestive heart failure (CHF), catecholaminergic agents may exert thermogenic effects that limit their beneficial effects in terms of global tissue oxygenation. Oxygen extraction ratio (O2ER) or mixed venous blood saturation (SvO2) might take into account better than cardiac index (CI) the resultant effect of such agents on peripheral oxygenation. We tested this hypothesis in a series of 20 patients with severe CHF and normal blood lactate levels undergoing pulmonary artery catheterization and receiving incremental doses of dobutamine: 0 (Do), 5 (D5), 10 (D10), and 15 micrograms/kg/min (D15). A significant dose-effect relationship (p < 0.01) was found between dose of dobutamine and CI (CI = 0.06 dose + 1.82). By contrast, no dose-effect relationship was observed between dobutamine dose and either O2ER or SvO2. Indeed, a biphasic profile was observed for O2ER and SvO2. From D0 to D10, O2ER decreased (from 45 +/- 6 to 35 +/- 7 percent) and SvO2 increased (from 52 +/- 7 to 62 +/- 7 percent). From D10 to D15, no further change was observed for both parameters. This latter finding was related to a significant increase in VO2 at D15 (p < 0.01). In these normolactatemic patients with unchanged VO2 from D0 to D10 while DO2 linearly increased (from D0 to D15), the increase in VO2 at D15 was probably due to an increase in oxygen demand induced by the drug. Our results suggest that dobutamine at a dose of 15 micrograms/kg/min can induce an increase in O2 demand that might offset the improvement in CI. Thus, in patients with CHF, oxygen-derived parameters such as O2ER and SvO2 should be more appropriate than CI to assess the efficacy of dobutamine.

Adult↗
PubMed1993

Cardiorespiratory effects of pressure-controlled ventilation with and without inverse ratio in the adult respiratory distress syndrome.

To assess the cardiorespiratory effects of pressure-controlled ventilation (PCV) and pressure-controlled inverse ratio ventilation (PC-IRV), we compared pressure-controlled ventilation with an inspiratory-to-expiratory time ratio (I/E) of 1/2 (PCV) and of 2/1 (PC-IRV) to volume-controlled ventilation (VCV) with an I/E of 1/2 in 10 patients suffering from the adult respiratory distress syndrome. In all modes, the inspiratory oxygen fraction, tidal volume, respiratory rate, and total positive end-expiratory pressure (PEEPt = applied PEEP + intrinsic PEEP) were kept constant. Each ventilatory mode was applied for 1 h in a randomized order. No significant differences in PaO2 were observed among the three modes. The PaCO2 was lower (p < 0.05) in PC-IRV (39 +/- 4 mm Hg) than in PCV (43 +/- 5 mm Hg) and in VCV (45 +/- 5 mm Hg). The peak airway pressure was significantly lower in PC-IRV than in PCV (p < 0.05) and in PCV than in VCV (p < 0.05), but plateau pressure was not different in the 3 modes. The mean airway pressure (mPaw) was significantly higher (p < 0.05) in PC-IRV (21.4 +/- 0.7 cm H2O) than in PCV (17.1 +/- 0.7 cm H2O) and VCV (16.4 +/- 0.5 cm H2O). As a consequence of this increased mPaw, PC-IRV induced a decrease in cardiac index (CI) (3.3 +/- 0.2 vs 3.7 +/- 0.2 L/min/m2 in VCV; p < 0.05) and hence in oxygen delivery (DO2) (424 +/- 28 vs 469 +/- 38 ml/min/m2 in VCV; p < 0.05). Our results suggest that neither PCV nor PC-IRV bring any benefit over VCV in terms of arterial oxygenation. Moreover, the increase in mPaw induced by PC-IRV may be deleterious to the CI and DO2.

Adult↗
PubMed1993

Fatal disseminated infection by Scedosporium inflatum after bone marrow transplantation.

A case of disseminated infection caused by Scedosporium inflatum is reported in a patient undergoing autologous bone marrow transplantation for acute myeloblastic leukemia. The fungus was isolated from a blood culture and necropsy studies showed a disseminated infection involving numerous organs. In vitro studies showed the isolate to be resistant to amphotericin B, 5-fluorocytosine, ketoconazole and miconazole.

Bone Marrow Transplantation↗
PubMed1993

[Chromobacterium violaceum, opportunist pathogenic bacteria in tropical and subtropical regions].

Chromobacterium violaceum is isolated from soil and waters in tropical and subtropical areas. This Gram negative bacillus is considered as a saprophyte, but occasionally it can act as an opportunistic pathogen for animals and man, and cause fatal septicaemia from skin lesion with many liver and lung abscesses. Classification, nomenclature, media used to isolation, characters useful to identification (morphology, cultural and biochemical traits, violacein pigmentation), differentiation from related violet-pigmented species and from Vibrionaceae (when C. violaceum cultures are not pigmented), antibiotics resistance and susceptibility, experimental and natural pathogenicity are emphasized.

Animals↗
PubMed1993

Down-regulation of c-myc gene is not obligatory for growth inhibition and differentiation of human myeloid leukemia cells.

Suppression of c-myc expression is observed during induced differentiation of several myeloid cell lines and it has been attributed to the cell growth arrest that accompanies terminal differentiation. To dissect the role of c-Myc in the proliferation-differentiation switch we have studied c-myc expression in K562 cells exposed to several chemical agents. This model system allowed us to discriminate between the growth arrest and differentiation phenomena as well as the induction of differentiation along two different lineages (erythroid and myelomonocytic). Our results showed that c-myc expression did not significantly decrease when growth inhibition is reversible, either by treatment with a differentiating agent such as hydroxyurea (which induced erythroid differentiation) or by a non-differentiating agent such as interferon-alpha. In contrast, c-myc expression decreased when cells underwent terminal differentiation, either along the myelomonocytic (by 12-O-tetradecanoylphorbol-13-acetate) or erythroid (by 1-beta-D-arabinofuranosylcytosine) lineages. These results indicated that c-myc down-regulation is not obligatory for growth arrest and non-terminal differentiation of human myeloid cells. In contrast, c-myc down-regulation occurred in terminal differentiation, but induction of myelomonocytic differentiation resulted in a greater loss of c-myc mRNA than induction of erythroid differentiation.

Cell Differentiation↗
PubMed1993

Invasive pulmonary aspergillosis prior to BMT in acute leukemia patients does not predict a poor outcome.

Eight patients with acute leukemia (AL) and invasive pulmonary aspergillosis (IPA) developing during previous antileukemic therapy underwent BMT (autologous in 6 cases and allogeneic 2). IPA was treated prior to BMT with full doses of amphotericin B, associated with surgical resection in three cases. One patient was treated with amphotericin B and itraconazole. Prior to BMT, seven patients had minimal residual pulmonary lesions. All patients received amphotericin B (0.5 mg/kg/day) during the aplastic period prior to engraftment. One patient died of Gram-negative septic shock before engraftment. Seven patients achieved complete hematological engraftment without any evidence of IPA reactivation. Amphotericin B was well tolerated with only minimal transient renal dysfunction in three patients. Later pulmonary complications related to IPA were observed in only one patient who developed a self-limited episode of hemoptysis. One patient died of CMV pneumonitis and two of leukemia relapse. Four patients survive disease-free and without complications related to IPA. We conclude that the reactivation of correctly treated IPA can be successfully prevented in BMT patients by use of prophylactic amphotericin B. With this approach, prior IPA is not a contraindication to BMT.

Adolescent↗
PubMed1993

Recombinant human GM-CSF enhances T cell-mediated cytotoxic function after ABMT for hematological malignancies.

The interactions of GM-CSF with cells of lymphoid lineage are not well understood and their clinical use has been focused on the acceleration of hematopoietic recovery. However, several reports have shown that human GM-CSF can affect certain T lymphocyte in vitro cytotoxic functions. To assess whether recombinant human GM-CSF (rhGM-CSF) has a more broadly based activity in the immune system, we studied its in vivo effects on endogenously-generated killer function in patients undergoing ABMT for hematologic malignancies. Eleven patients received rhGM-CSF after ABMT: eight received rhGM-CSF as a 2-h infusion daily from days +3 to +17 and three received rhGM-CSF until reaching > 500 x 10(6)/l granulocytes. Eight patients not enrolled in the rhGM-CSF therapy protocol served as controls. Natural killer (NK) cell activity and activated killer (AK) cell activity were studied before conditioning, during rhGM-CSF therapy and after withdrawal of GM-CSF. rhGM-CSF therapy does not affect NK activity. Circulating lymphocytes with the ability to kill AK-sensitive targets appear spontaneously in control ABMT patients. AK activity was 1.6 +/- 0.8% before ABMT increasing to 9 +/- 2.5% and 14 +/- 2.1% at 2 and 3 weeks after ABMT, respectively (p = 0.002). In rhGM-CSF-treated patients this phenomenon also occurs. AK activity increased from 2.4 +/- 1.5% before ABMT to 33.6 +/- 8.1% during rhGM-CSF administration (p = 0.001) and 17.5 +/- 3.4% after withdrawal (p = 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Differential expression of ras protooncogenes during in vitro differentiation of human erythroleukemia cells.

We have compared the expression of the ras protooncogene family (H-, K-, and N-ras) in leukemia cell differentiation utilizing as a model K562 and HEL erythroleukemia cells treated either with 1-beta-arabinofuranosylcytosine or 12-O-tetradecanoylphorbol-13-acetate (TPA). 1-beta-D-Arabinofuranosylcytosine induced terminal erythroid differentiation of K562 cells, while TPA induced myeloid differentiation of K562 and HEL cells, resulting in myelomonocytic-like cells expressing macrophagic and megakaryocytic markers. H-ras mRNA levels showed a dramatic decrease in K562 cells subjected to erythroid and myelomonocytic differentiation. The same result was found at the protein level for p21H-ras. Expression of K-ras and N-ras in K562 cells also decreased with differentiation, although significant mRNA levels remained despite cessation of cell proliferation. The decrease in K-ras expression was greater for TPA-treated cells than for 1-beta-arabinofuranosylcytosine-treated cells. TPA-induced myelomonocytic differentiation in HEL cells also resulted in a dramatic down-regulation of H-ras mRNA levels. Thus, by using a leukemia cell line able to differentiate along two different lineages, our results reveal a lineage-specific modulation of ras gene family expression.

Cell Differentiation↗
PubMed1992

Structure and regulation of yeast HEM3, the gene for porphobilinogen deaminase.

Porphobilinogen deaminase is the third enzyme in the heme biosynthetic pathway. hem3 mutants in Saccharomyces cerevisiae are deficient in porphobilinogen deaminase activity. We have isolated the HEM3 gene by complementation of the heme auxotrophy of a hem3 mutant. Sequence analysis reveals an open reading frame of 981 nucleotides. The derived amino acid sequence of the protein encoded by HEM3 shows extensive homology to the reported sequences for porphobilinogen deaminase from a number of other sources, indicating that HEM3 is the structural gene for porphobilinogen deaminase. Earlier reports have suggested that expression of HEM3 is induced by porphobilinogen, the substrate of the encoded enzyme. We have investigated the transcription of HEM3 and have found that it is not affected by the ability of the cell to make porphobilinogen or heme. However, we have found that HAP2 and HAP3 gene products are involved in the expression of HEM3. An important element required for expression of HEM3 has been localized to a small region that contains a sequence homologous to the HAP2-3-4 binding sites of several genes including HEM1. These findings suggest that HEM3 expression is regulated in the same manner as that of HEM1 which encodes the first enzyme of the heme biosynthetic pathway.

Amino Acid Sequence↗
PubMed1992

Ice Nucleation Activity in Fusarium acuminatum and Fusarium avenaceum.

Twenty fungal genera, including 14 Fusarium species, were examined for ice nucleation activity at -5.0 degrees C, and this activity was found only in Fusarium acuminatum and Fusarium avenaceum. This characteristic is unique to these two species. Ice nucleation activity of F. avenaceum was compared with ice nucleation activity of a Pseudomonas sp. strain. Cumulative nucleus spectra are similar for both microorganisms, while the maximum temperatures of ice nucleation were -2.5 degrees C for F. avenaceum and -1.0 degrees C for the bacteria. Ice nucleation activity of F. avenaceum was stable at pH levels from 1 to 13 and tolerated temperature treatments up to 60 degrees C, suggesting that these ice nuclei are more similar to lichen ice nuclei than to bacterial ones. Ice nuclei of F. avenaceum, unlike bacterial ice nuclei, pass through a 0.22-mum-pore-size filter. Fusarial nuclei share some characteristics with the so-called leaf-derived nuclei with which they might be identified: they are cell free and stable up to 60 degrees C, and they are found in the same kinds of environment. Highly stable ice nuclei produced by fast-growing microorganisms have potential applications in biotechnology. This is the first report of ice nucleation activity in free-living fungi.

Journal Article↗
PubMed1992

Effects of cardiovascular drugs on oxygen consumption/oxygen delivery relationship in patients with congestive heart failure.

The oxygen consumption (VO2)/oxygen delivery (DO2) relationship was analyzed in ten patients with severe congestive heart failure (CHF) and normal blood lactate levels. First dobutamine and then enoximone, after a washout period, were administered to each patient to increase cardiac output by at least 15 percent. Similar increases in DO2 were obtained with both drugs: from 285 +/- 46 to 393 +/- 87 ml/min/m2 for dobutamine, and from 285 +/- 54 to 392 +/- 99 ml/min/m2 for enoximone. However, while VO2 did not change (132 +/- 24 vs 132 +/- 21 ml/min/m2) (VO2/DO2 independency) with a dobutamine infusion (mean dose of 10 +/- 2 micrograms/kg/min), a significant increase in VO2 from 134 +/- 22 to 157 +/- 21 ml/min/m2 was observed with a bolus infusion of enoximone (mean dose of 1.7 +/- 0.5 mg/kg). These results, observed in patients with CHF without patent oxygen debt, suggest that an artefactual VO2/DO2 dependency might be induced by the cardiovascular drug used to elevate DO2, probably because of a drug-induced oxygen demand increase.

Acute Disease↗
PubMed1992

Autologous bone marrow transplantation in 22 adult patients with lymphoblastic lymphoma responsive to conventional dose chemotherapy.

In order to clarify the role of autologous bone marrow transplantation in adult lymphoblastic lymphoma (LBL) patients we have conducted a retrospective multi-institutional Spanish survey. Twenty-two adult patients, 20 males, two females, age 14-52 years (median 25.5) with LBL were treated with high-dose chemoradiotherapy and autologous bone marrow support. Fourteen cases were transplanted in first complete remission (CR1) and eight with other chemosensitive status (four later CR, two partial remissions and two sensitive relapses). From the 14 cases transplanted in CR1, four had previous bone marrow involvement and one meningeal infiltration; eight cases were Ann-Arbor stage IV and fulfilled accepted high-risk criteria for relapse. The conditioning regimen consisted of cyclophosphamide (60 mg/kg x 2) and total body irradiation (9-12 Gy) in 16 cases and high dose chemotherapy in six. The procedure-related mortality was 9% (7% in CR1 patients). The actuarial 2-year overall survival for CR1 patients was 85% at a median follow-up of 19 months. Disease-free survival (DFS) was 77%. In patients with less favourable disease status the 2-year overall and DFS were 73% and 50% respectively. In this study the DFS in CR1 patients was not influenced by bone marrow involvement or high-risk criteria predictive for relapse. These results support the effectiveness of this procedure, mainly for patients in CR1.

Adolescent↗
PubMed1991

[Demonstration of tissue hypoxia due to defective peripheral extraction of oxygen (O2) during brain death].

Adequate oxygenation of potentially transplantable tissues must be maintained in patients in a state of cerebral death. An analysis of the relationship between oxygen consumption and arterial oxygen supply shows that proven tissue hypoxia occurs associated with high lactate in almost all patients in a state of cerebral death, even before haemodynamic parameters (blood pressure, heart rate) reach alarming levels. This tissue hypoxia, which exists even though arterial supply remains high, would suggest that there is a defect in peripheral oxygen extraction during the state of cerebral death. Intensive units should take this into account when maintaining these patients.

Adult↗
PubMed1991

[Infectious complications in bone marrow transplantation].

BACKGROUND: Initially, the aim of the present study was to evaluate the incidence and implicated organisms in the infections in patients receiving a bone marrow transplants (BMT). METHODS: 194 febrile episodes (FE) were evaluated in 115 patients having received a BMT between 1980 and 1987. The analysis was carried out at three different moments: during the period of most marked neutropenia (period I) to the 100th day after BMT (period II) and beyond the 100th day (period III). RESULTS: The unequivocal confirmation that FE was infective was found in 62% of cases (confirmation was microbiological in 46% and clinical in 16%), while 31% of FE were considered as possible infections and the remaining 7% as doubtful infections. The causative organisms were bacteria (73%), viruses (10%), fungi (8%), and combinations of them (polymicrobial infections) (9%). Gram negative and Gram positive organisms were more common, respectively, in period I and in periods II and III (p = 0.02). Bacteremia was the commonest cause of confirmed infection. The overall mortality rate due to infection was 18%. There was a remarkably high mortality from pneumonia (54%) and a low mortality in patients with sepsis (6%) (p less than 0.0001). The number of FE was lower in patients with autografts than those with allografts (p = 0.08). 33% of the FE in patients with allografts were coincident with acute or chronic graft-versus-host disease, and in two thirds of them infections was confirmed. CONCLUSIONS: Infection represents a major complication of BMT. The different antimicrobial treatments used in association with bone marrow grafting allowed us to control most FEs. Pneumonia was the most severe infective localization and the leading cause of death. Mortality rate due to sepsis was small.

Adolescent↗