Biomedical subjects

C Rollin

Publications and source records attributed to C Rollin.

15 recordsLinked to original sources

PubMed1998

Carbon-flux distribution in the central metabolic pathways of Corynebacterium glutamicum during growth on fructose.

Growth of Corynebacterium glutamicum on fructose was significantly less than that obtained on glucose, despite similar rates of substrate uptake. This was in part due to the production of overflow metabolites (dihydroxyacetone and lactate) but also to the increased production of CO2 during growth on fructose. These differences in carbon-metabolite accumulation are indicative of a different pattern of carbon-flux distribution through the central metabolic pathways. Growth on glucose has been previously shown to involve a high flux (> 50% of total glucose consumption) via the pentose pathway to generate anabolic reducing equivalents. NMR analysis of carbon-isotope distribution patterns of the glutamate pool after growth on 1-13C- or 6-13C-enriched fructose indicates that the contribution of the pentose pathway is significantly diminished during exponential growth on fructose with glycolysis being the predominant pathway (80% of total fructose consumption). The increased flux through glycolysis during growth on fructose is associated with an increased NADH/NAD+ ratio susceptible to inhibit both glyceraldehyde-3-phosphate dehydrogenase and pyruvate dehydrogenase, and provoking the overflow of metabolites derived from the substrates of these two enzymes. The biomass yield observed experimentally is higher than can be estimated from the apparent quantity of NADPH associated with the pentose pathway and the flux through isocitrate dehydrogenase, suggesting an additional reaction yielding NADPH. This may involve a modified tricarboxylic acid cycle involving malic enzyme, expressed to significantly higher levels during growth on fructose than on glucose, and a pyruvate carboxylating anaplerotic enzyme.

Biological Transport↗

PubMed1998

Cefepime versus imipenem-cilastatin as empirical monotherapy in 400 febrile patients with short duration neutropenia. CEMIC (Study Group of Infectious Diseases in Cancer).

This open, comparative, randomized, multicentre equivalence study compared cefepime 2 g bd and imipenem-cilastatin 1 g tds (50 mg/kg/day) as empirical monotherapy for febrile episodes in a homogeneous cohort of cancer patients with short duration neutropenia following chemotherapy for solid tumour, lymphoma or myeloma. The study was conducted in 17 French anti-cancer centres in 1995 and 1996. Response to monotherapy was assessed 7 days after treatment and was based on resolution of fever and signs and symptoms, eradication of pathogens, absence of new infection, relapse, and death of infectious origin, without addition of other antibiotics. Patients were treated for a minimum of 4 days. Of the 400 episodes randomized, 344 (86%) were evaluable for efficacy. Patient characteristics were comparable between treatment groups. Success of monotherapy was observed in 79% of episodes with cefepime and 72% with imipenem-cilastatin (equivalence, P <0.0001). The response rate for microbiologically documented infections was 66% with cefepime and 61% with imipenem-cilastatin (bacteraemic episodes: 63% for cefepime; 44% for imipenem-cilastatin). A second antibiotic (usually a glycopeptide) was added in 20% and 21% of the cases, respectively. Overall, the response to therapy, with or without an additional antibiotic, was 95% (cefepime) and 90% (imipenem-cilastatin). Survival was similar in both groups (95% and 98%, respectively). Cefepime treatment was better tolerated, with 9% of the patients experiencing related intercurrent events compared with 19% in the imipenem-cilastatin group (P = 0.003). Nausea/vomiting was significantly more frequent in the imipenem-cilastatin group (15%) than in the cefepime group (5%; P = 0.001). Cefepime monotherapy was as effective as, and better tolerated than, imipenem-cilastatin in the empirical treatment of fever during short duration neutropenia.

Antineoplastic Agents↗

PubMed1998

Cefepine vs. ceftazidime treatment of pyelonephritis: a European, randomized, controlled study of 300 pediatric cases. European Society for Paediatric Infectious Diseases (ESPID) Pyelonephritis Study Group.

BACKGROUND: Cefepime has been used in clinical therapeutic trials for meningitis, serious infection and febrile neutropenia, comprising more than 800 pediatric patients. This agent has also been used in patients 12 years of age and older with uncomplicated and complicated urinary tract infections including pyelonephritis, but not in younger patients. In this study the safety and efficacy of cefepime were compared with those of ceftazidime for treatment of pyelonephritis in pediatric patients younger than 12 years of age. METHODS: Two hundred ninety-nine pediatric patients (ages 1 month to 12 years) with pyelonephritis (300 episodes) were enrolled in a randomized, open label, multicenter trial. Individual results were evaluated by a blinded committee of experts. Cefepime was compared with ceftazidime, both administered parenterally at 50 mg/kg every 8 h. Patients were to receive the assigned study drug until at least 48 h after becoming afebrile. The i.v. treatment was then to be continued or replaced by oral trimethoprimsulfamethoxazole for a maximum of 12 to 14 days. RESULTS: The predominant causative pathogens were Escherichia coli, 88%; Proteus spp., 6%; Pseudomonas aeruginosa, 2%; and Klebsiella spp., 2%. Bacteriologic eradication was achieved in 96 and 94% of cefepime and ceftazidime patients, respectively, at the end of i.v. study drug treatment and was maintained in 94 and 91%, respectively, at the end of total study therapy. After study therapy bacteriologic eradication was maintained after 4 to 6 weeks in 86% of cefepime cases and in 83% of ceftazidime cases. A satisfactory clinical response occurred in 98 and 96% of cefepime and ceftazidime patients, respectively, at the end of i.v. treatment and in 93% at the end of total study therapy in both treatment arms. Drug-related clinical adverse events occurred in 14 cefepime patients (91%) and in 10 ceftazidime patients (7%). CONCLUSIONS: Cefepime and ceftazidime are equally safe and efficacious treatment for pyelonephritis in pediatric patients.

Administration, Oral↗

PubMed1997

Cefepime/amikacin versus ceftazidime/amikacin as empirical therapy for febrile episodes in neutropenic patients: a comparative study. The French Cefepime Study Group.

We conducted a randomized multicenter study to compare the efficacy and safety of two antibiotic regimens (cefepime [2 g b.i.d.] plus amikacin or ceftazidime [2 g t.i.d.] plus amikacin) as first-line therapy for fever in patients with hematologic malignancies and neutropenia. A total of 353 patients were randomized according to a 2:1 (cefepime:ceftazidime) ratio. Two hundred-twelve patients in the cefepime group and 107 in the ceftazidime group (90% of all patients) were evaluable for efficacy. The polymorphonuclear neutrophil count was < 100/mm3 on enrollment for 70% of the patients. The mean duration of neutropenia was 26 days. The efficacy in both study arms was comparable, although a trend in favor of cefepime was seen in terms of therapeutic success (response rate, 27% vs. 21% for the ceftazidime group). The overall response rate after glycopeptides were added to the regimens was 60% for the cefepime group and 51% for the ceftazidime group; the bacterial eradication rates were 81% vs. 76%, respectively, and the rates of new bacterial infections were 14% vs. 18%, respectively. We conclude that the combination cefepime/amikacin is at least as effective as the reference regimen of ceftazidime/amikacin in this setting.

Amikacin↗

PubMed1995

13C-NMR studies of Corynebacterium melassecola metabolic pathways.

Coryneform bacteria are widely used to produce amino acids, in particularly glutamic acid, by fermentation. To study the metabolic fate of glucose as the carbon source, we developed a method to analyze intracellular extracts by NMR and HPLC. The intracellular metabolites represent the metabolic state of the cells. Glutamic acid was the major metabolic intermediate found in the extracts and its 13C isotopic enrichment reflected that of pyruvic acid. Thus, it was possible to determine the respective contributions of the two major glucose catabolic pathways during the exponential growth phase; glycolysis (55%) and the pentose phosphate pathway (45%). Absolute glutamate 13C enrichments resulting from the incorporation of [1-13C]glucose were determined to quantify the contribution of several metabolic pathways such as anaplerotic pathways (61%; phosphoenolpyruvate carboxylase, pyruvate carboxylase, malic enzyme), a single turn (32%) or multiple turns of the Krebs cycle and the glyoxylate shunt, to oxaloacetate synthesis. A previously described model was adapted to C. melassecola for these calculations. The Krebs cycle was active, whereas the glyoxylate shunt was inactive in exponentially growing cells of C. melassecola with glucose as the sole carbon source. The contributions of anaplerotic enzymes and pyruvate dehydrogenase to replenishing the Krebs' cycle were determined to be 38% and 62%, respectively.

Carbon Isotopes↗

PubMed1994

Comparative efficacy and safety of cefprozil and amoxycillin/clavulanate in the treatment of acute otitis media in children.

Cefprozil is a new oral cephalosporin with activity against the most common pathogens isolated in acute otitis media. This randomized study enrolled 361 patients (mean age 29 months). Physical examination and culture via tympanocentesis were required less than 48 h before therapy. One hundred and ninety-one patients were evaluable for clinical efficacy; 99 received cefprozil (20 mg/kg/day bd) and 92 received amoxycillin/clavulanate (13.3 mg/kg/day tid). Duration of treatment was 7-9 days for 81 patients, 10 days for 105 patients and 11-16 days for five patients. The treatment groups were comparable with respect to demographics, severity of infection and number of previous episodes. Clinical evaluations of efficacy were based on physical examination including otoscopy within a 14 day period after therapy. Satisfactory clinical responses were achieved in 84% of cefprozil-treated patients and 87% of amoxycillin/clavulanate-treated patients. Pathogens most commonly isolated included Haemophilus influenzae (33%) and Streptococcus pneumoniae (22%). All 361 patients were evaluable for safety. Adverse clinical events were reported in 13% (24) of cefprozil-treated patients and 20% (36) of amoxycillin/clavulanate-treated patients. Cefprozil, administered twice a day, is comparable to a regimen of amoxycillin/clavulanate three times a day in the treatment of acute otitis media in children.

Acute Disease↗

PubMed1993

Recognition of the colicin A N-terminal epitope 1C11 in vitro and in vivo in Escherichia coli by its cognate monoclonal antibody.

We demonstrate that the 1C10 monoclonal antibody (mAb) directed against the N-terminal domain of the colicin A recognizes a 13 residue-region (13Thr-Gly-Trp-Ser-Ser-Glu-Arg-Gly-Ser-Gly-Pro- Asp-Pro25). When this peptide is inserted into a protein in the amino-terminal or an internal position, the tagged protein is efficiently detected by the 1C11 mAb either by immunoblotting or immunoprecipitation. In vitro, the minimal structure required for detection using the pepscan system is 19Arg-Gly-Ser-Gly-Pro-Glu-Pro25, indicating that in vivo the proper exposure of the epitope requires additional residues. The construction of a versatile vector allowing overproduction of tagged proteins is described. Various applications of the 1C11 epitope are mentioned. This epitope did not alter the function of any of the proteins so far tested.

Amino Acid Sequence↗

PubMed1993

Comparative study of availability of prednisolone after intestinal infusion of prednisolone metasulfobenzoate and prednisone.

The role of intestinal absorption in the differential availability of prednisone (PN) and prednisolone metasulfobenzoate (PO-MS), which might account for clinical resistance to PO-MS, has been studied by an infusion technique. In a randomized cross-over design trial, a solution in isotonic saline of PN or PO-MS (115 mg.l-1 was infused at 5 ml.min-1 for 2 h, into a 25 cm segment of jejunum in 8 healthy fasting subjects. The intestinal content was partly collected and the flow rate at the end of the test segment was determined by using a water movement marker (PEG 4000). Plasma, intestinal and urine concentrations of PN and PO were determined by liquid chromatography. From the data on PO, the active molecule, the systemic availability of PO-MS was significantly smaller than of PN, with the respective mean AUCs being 1.71 and 3.60 mg.h-1. The difference was associated with smaller mean Cmax, 0.20 vs 0.64 mg.l-1, higher mean tmax, 2.94 vs 2.06 h and lower mean ka, 0.98 vs 2.18 l/h after PO-MS. No significant difference was found in the half-life or renal clearance of the formulations tested. The mean MRT was significantly increased after PO-MS, 6.82 vs 5.30 h. The observed difference probably reflected a difference in intestinal absorption. The mean absorption in the test segment of PO-MS was significantly smaller at 17.4 vs 85.5% for PN. The ester form may be a limiting factor in the intestinal absorption of PO.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1993

A non-comparative study of the efficacy and tolerance of cefepime in combination with amikacin in the treatment of severe infections in patients in intensive care.

Patients in intensive care units (ICUs) are at increased risk of developing nosocomial infections. This is of special concern in the immunocompromised patient, particularly with regard to multiresistant pathogens. We evaluated the effectiveness of cefepime 2 g bd in combination with amikacin 7.5 mg/kg bd for the treatment of severe bacterial infection in 118 ICU patients, including 113 patients with nosocomial lower respiratory tract infections (LRTI) (mean age, 51 years). Ninety-six per cent (108/113) of the LRTI patients required respiratory assistance and 12% (14/113) had associated septicaemia/bacteraemia. Eighty-four per cent (95/113) had clinical signs of sepsis and 35% (39/113) had features of septic shock. The mean Simplified Acute Physiologic Score (SAPS) was 12 at inclusion. Seventy-nine patients with LRTI were clinically and bacteriologically evaluable. The causative pathogens were representative of those usually isolated in ICUs: Staphylococcus aureus (19%); Pseudomonas aeruginosa (14%); and Klebsiella, Enterobacter and Serratia spp. (17%). The clinical cure rate was 86% (68/79) while the pathogen eradication rate was 91% (107/117). Of the patients with associated septicaemia/bacteraemia, 89% (8/9) of the pathogens were eliminated. Cefepime-amikacin combination therapy was well tolerated; two patients discontinued treatment due to rashes. Combination therapy with cefepime 2 g bd and amikacin 7.5 mg/kg bd appears safe and effective for the treatment of nosocomial pneumonia in patients hospitalized in ICUs. Further comparative controlled studies are justified.

Adolescent↗

PubMed1993

In-vitro antibacterial activity of cefepime: a multicentre study.

The antimicrobial activity of cefepime, a new broad-spectrum parenteral cephalosporin, was evaluated in vitro against 1757 recent clinical Gram-positive and Gram-negative isolates. Cefepime was active at low concentrations (MIC50 values < or = 0.06 mg/L and MIC90 values < or = 0.12 mg/L) against non-cephalosporinase-producing Enterobacteriaceae (Escherichia coli, Proteus mirabilis, Salmonella spp. and Shigella spp.). For Klebsiella pneumoniae, MICs were between 0.016 and 16 mg/L; the highest MIC values were observed for extended-spectrum beta-lactamase-producing strains. Against Enterobacteriaceae, such as cephalosporinase producing Enterobacter cloacae, MICs were < or = 0.5 mg/L, but MICs against cephalosporinase hyperproducing strains were generally higher. Ticarcillin-sensitive strains of Pseudomonas aeruginosa were inhibited by cefepime concentrations of 0.5-16 mg/L, while cefepime MICs were 8-64 mg/L for strains resistant to ticarcillin. The cefepime MIC50 value for Haemophilus spp. including many resistant to amoxycillin, was 0.03 mg/L. Against methicillin-sensitive strains of Staphylococcus aureus, cefepime MICs were 0.5-16 mg/L; MICs against methicillin-resistant staphylococci were 16- > 128 mg/L). Against methicillin-sensitive coagulase-negative staphylococci, cefepime MIC values were 0.03-16 mg/L; corresponding values for methicillin-resistant strains were 2-128 mg/L. Streptococci (Groups A, C and G) were sensitive to cefepime with MICs ranging from < or = 0.008-2 mg/L (MIC50, 0.03 mg/L; MIC90, 0.25 mg/L). The activity of cefepime against Group B streptococci and pneumococci were comparable, with MIC50 values of 0.12 and 0.25 mg/L, respectively, and MIC90 values of 0.03 and 0.25 mg/L, respectively. Most enterococci and all Listeria monocytogenes strains had MICs > or = 32 mg/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteria↗

PubMed1993

Personal development planning.

Since the introduction of general management into the NHS in 1985, greater emphasis has been placed on managing the service through clearly defined objectives. Jill Sandford and Christine Rollin describe Lifespan Healthcare's personal development plan for managers, and report on some of the benefits it has brought the organisation.

Education, Continuing↗

PubMed1989

Osmoregulation of vasopressin secretion and thirst during the estrous cycle of pigs.

The influence of the reproductive cycle on ingestive behaviors, osmotically induced fluid intake, and peripheral blood levels of several hormones involved in fluid electrolyte balance was investigated in young adult female pigs. Food, water, and salt intakes and plasma aldosterone levels were significantly lower during estrus compared with the luteal and follicular phases, whereas plasma sodium (PNa) was higher. Plasma renin activity and lysine vasopressin (LVP) levels did not vary with the cycle. Regression analyses of the relationship between plasma LVP and PNa in unanesthetized, unstressed animals infused for 2 h with intravenous 5% NaCl revealed no significant differences in terms of the osmotic threshold and sensitivity of LVP release at different stages of the reproductive cycle. In contrast, when osmotic loading was carried out with continuous access to water, the osmotic threshold for drinking was found to be significantly higher and the rate of drinking lower during estrus. The results indicate that in the adult female pig the stage of the reproductive cycle has an influence on ingestive behaviors and the osmoregulation of thirst. Osmoregulation of vasopressin secretion, on the other hand, appears to be independent of the estrous cycle in this species.

Animals↗

PubMed1989

Sex differences result in increased morbidity from hyponatremia in female rats.

The development of symptomatic hyponatremia in otherwise healthy young women can result in death or permanent brain damage. The reasons for the increased female susceptibility to complications from hyponatremia are, however, unclear. To determine whether mechanisms that normally defend the brain against damage from hyponatremia are less effective in females than males, we studied both sodium transport in the brains of hyponatremic male and female rats and the effects of parenteral arginine vasopressin on brain high-energy phosphate metabolism and intracellular pH. Basal sodium uptake in synaptosomes prepared from whole brain of females (2.20 nmol/mg protein) and males (2.98 nmol/mg protein) was not statistically different. In contrast, veratridine-stimulated sodium uptake in female brain was 8.20 nmol/mg protein, which was 86% greater (P less than 0.001) than the 6.12 nmol/mg protein observed for male brain. Additionally, sodium uptake between 5 and 60 s was significantly (P less than 0.001) greater in females than males. These data suggest that the Na+-K+-adenosinetriphosphatase (ATPase) pump function in female rat brain synaptosomes is less effective than in males. To determine whether arginine vasopressin, a peptide hormone that promotes water retention by the kidney, had any effects on cerebral energy metabolism, we performed phosphorus-31 (31P) magnetic resonance spectroscopy (MRS) studies on the brain of normonatremic young adult male and female rats subjected to high (20 IU) peripheral doses of arginine vasopressin. We found decreased high-energy phosphate generation, elevated inorganic phosphate, and intracellular acidosis after arginine vasopressin administration in females but not males.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗

PubMed1989

Nicardipine reduces ischemic brain injury. Magnetic resonance imaging/spectroscopy study in cats.

We investigated whether the calcium channel entry blocker nicardipine would reduce ischemic brain damage in barbiturate-anesthetized cats subjected to permanent unilateral occlusion of the middle cerebral artery. The evolution of cerebral injury was assessed in vivo in 24 cats by a combination of proton magnetic resonance imaging and phosphorus-31 magnetic resonance spectroscopy for 5 hours following occlusion. Immediately thereafter, the volume of histochemically ischemic brain tissue was determined planimetrically in triphenyl tetrazolium chloride-stained serial coronal sections. Nicardipine was initially administered as an intravenous bolus injection of 10 mg/kg/hr 15 minutes before or 15 minutes after occlusion, followed by continuous infusion at 8 mg/kg/hr for the 5 hours of the experiment. Compared with untreated controls, cats that received nicardipine before or after occlusion showed a significant reduction in the extent of edema in the ipsilateral cerebral cortex, internal capsule, and basal ganglia. The results of phosphorus-31 magnetic resonance spectroscopy studies suggest that nicardipine may protect against cerebral ischemic damage by an action on cellular metabolic processes that preserve high-energy phosphates during the ischemic period.

Animals↗

PubMedDate not supplied

Comparison of the immune response elicited by a free peptide and a lipopeptide construct.

Among the synthetic peptides derived from the 28-kDa Schistosoma mansoni gluthatione-S-transferase (Sm28GST), the C-terminal peptide, comprising amino acid residues 190 to 211, represents a major T-cell epitope in both infected humans and Sm28GST-immunized mice. The aim of this study was to determine the nature of the immune response induced by the 190-211 peptide coupled to a fatty acid (lipopeptide construction) in comparison to the free form. We explored B- and T-cell responses elicited by these two peptidic constructions in three different mouse strains (BALB/c, CBA/N and C57B1/6). For all strains, the addition of a lipid chain to the 190-211 peptide greatly modified its immunogenicity. The lipopeptide, compared to the free form, induced a greatly reduced antibody response against the peptide, whereas the production of messenger for cytokines was greatly increased after immunization with the lipopeptide. Immunization with peptide led mainly to a Th1-type cytokine profile following antigenic restimulation in vitro, while lipopeptide, in general, induced a mixed profile, and that occurred most significantly with the production of messengers for the protective cytokines IFN-gamma and IL-2, even without antigenic restimulations. This modification of immunogenicity of a peptide by the addition of a lipid chain could be of value in the development of efficient peptide vaccines.

Animals↗