Biomedical subjects

A Barbot

Publications and source records attributed to A Barbot.

7 recordsLinked to original sources

PubMed2003

Pharmacokinetics and pharmacodynamics of sequential intravenous and subcutaneous teicoplanin in critically ill patients without vasopressors.

OBJECTIVE: To compare the pharmacokinetic parameters of sequential intravenous and subcutaneous teicoplanin in the plasma of surgical intensive care unit patients. DESIGN AND SETTING: Prospective, randomized, crossover study in the surgical ICU of a university hospital. PATIENTS: Twelve patients with a suspected nosocomial infection, a serum albumin level higher than 10 g/l, body mass index less than 28 kg/m(2), and estimated creatinine clearance higher than 70 ml/min. INTERVENTIONS: Teicoplanin was first administered intravenously as a loading dose of 6 mg/kg per 12 h for 48 h and then continued at a daily dose of 6 mg/kg. On the fourth day patients were randomized in two groups according to the order of the pharmacokinetic studies. MEASUREMENTS AND RESULTS: Serial plasma samples were obtained to measure teicoplanin levels. Compared with a 30-min intravenous infusion the peak concentration of teicoplanin after a 30-min subcutaneous administration occurred later (median 7 h, range 5-18) and was lower (16 micro g/ml, 9-31; vs. 73, 53-106). Despite large and unpredictable interindividual differences no significant differences between subcutaneous and intravenous administration were observed in: trough antibiotic concentrations (10 micro g/ml, 6-24; vs. 9, 5-30), the area under the teicoplanin plasma concentration vs. time curves from 0 to 24 h (AUC(0-24h); 309 micro g/ml per minute, 180-640; vs. 369, 171-955), the proportion of the dosing interval during which the plasma teicoplanin concentration exceeded 10 micro g/ml (96%, 0-100%; vs. 79%, 13-100%), and the ratio of AUC(0-24h) to 10 (77, 45-160; vs. 92, 43-239). CONCLUSIONS: In critically ill patients without vasopressors a switch to the subcutaneous teicoplanin after an initial intravenous therapy seems to give comparable pharmacodynamic indexes of therapeutic success.

Adolescent↗

PubMed2003

Speech recognition in elderly cochlear implant recipients.

The benefits of cochlear implantation in the adult and paediatric populations are well established. Cochlear implantation in the geriatric population still remains controversial because of the misconception that elderly patients might perform poorly. The purpose of this study was to report the speech performance of 16 patients over 65 years of age implanted with a Nucleus multichannel cochlear implant and to compare it with that of a control group of 14 adults aged between 41 and 59 years. At the 12 months postoperative evaluation, no significant differences were detected on speech performances between the elderly patients and the control group. The mean word recognition scores were 72.5% for the elderly group and 82% for the control group. The mean everyday sentence recognition scores were 72.5% for the elderly group and 85.7% for the control group. Overall, the results are encouraging and demonstrate that the elderly population with profound hearing loss obtain significant benefits from cochlear implantation despite the age-related auditory processing problems.

Adult↗

PubMed2002

[Multi-channel cochlear implant in cochlear ossification].

Cochlear ossification, considered until only a few years ago as a contraindication for cochlear implants (C.I.), may now be managed by means of a wide variety of surgical techniques. In cases with massive ossification, the drill-out circummodiolar technique described by Gantz et al. in 1988 and successively modified by Balkany et al. in 1997 may be adopted. The technique of electrode insertion in the scala vestibuli, perfected by Steenerson et al. in 1990, may be used when cochlear ossification has spread no further than the scala tympani. Other methods call for a groove to be drilled along the proximal tip of the basal turn of the cochlea (Cohen and Waltzman, 1993), the insertion of electrodes through the middle cranial fossa (Colletti et al., 2000), or the utilization of a double electrode array (Bredberg et al., 1997, Lenarz et al., 2001). This study reports the experience conducted at the Cochlear Implants Centre of the Otorhinolaryngoiatrics, Otological and Otoneurological Microsurgery Section of the University of Parma in a group of 15 patients who underwent C.I. in the presence of varying degrees of ossification. In 3 cases the ossification was limited to the region of the round window and a few millimetres of the scala tympani; cochleostomy was performed anteriorly and inferiorly to the anterior niche of the round window. In 11 cases (of which 3 of pediatric age), the ossification had spread to the horizontal portion of the scala tympani; in these cases, the electrodes were inserted in the scala vestibuli. The scala vestibuli was opened by drilling anteriorly to the round window and superiorly to the spiral ligament. In the only case of massively ossified cochlea, it was possible to partially insert the electrodes in a circum-modiolar tunnel. In the 12-month follow-up hearing test, the 3 patients with ossification of the round window region and the first millimetres of the scala tympani respectively averaged 61.6% in recognizing 2-syllable words and 59% in recognizing words embedded in phrases. The averages on the 12-month follow-up hearing test in the 8 adult patients who received the implant in the scala vestibuli were 80.6% in recognizing 2-syllable words and 89.1% in recognizing words in phrases. The 3 pediatric patients were classified on the Geers and Moog scale, which situated 2 of them in the 6th category of perception and 1 of them in the 4th category of perception. As regards the only case of massive cochlear ossification, the patient underwent surgery recently, and the sole follow-up available is the one conducted after only 3 months; the vowel identification average was 55%; the average on the VCV test was 31%; and the 2-syllable word recognition average was 20%.

Acoustic Stimulation↗

PubMed2001

Stabilization of recombinant adenovirus: site-directed mutagenesis of key asparagine residues in the hexon protein.

The quality and stability of recombinant adenovirus preparations for gene therapy trials are currently analyzed by anion-exchange HPLC. It was shown that the retention time of the adenovirus peak increased over the course of time upon storage in current liquid formulations. The number of isoaspartate residues at the outer surface of the particles also increased in parallel in these preparations. A recombinant adenovirus AV3760 was constructed with a modified hexon protein in which all four accessible Asn residues engaged in Asn-Gly pairs were changed into Leu (Asn244, Asn255, Asn437) or Ala (Asn276). The retention time of AV3760, as measured by HPLC, was unchanged after 2 months at +20 degrees C as opposed to the control adenovirus. This demonstrates that the shift in retention time is caused by an increase in carboxyl groups on the outer surface of the virion due to deamidation of the above Asn residues. The modifications introduced in the hexon protein reduced the rate of Asn deamidation, without adverse effects on the infectivity of the virions. By reducing microheterogeneity in recombinant adenovirus, this work represents a significant advance in the development of a stable pharmaceutical vector for gene therapy.

Adenoviridae↗

PubMed2001

Polypeptide composition of an adenovirus type 5 used in cancer gene therapy.

For cancer gene therapy, a recombinant adenovirus serotype 5 named RPR/INGN201 has been constructed by susbtitution of the E1 region with human tumor suppressor gene p53. The protein components of RPR/INGN201 virions were separated by reversed-phase HPLC and were individually identified by electrospray time-of-flight mass spectrometry and N-terminal sequencing, both on intact proteins and on their proteolytic fragments after trypsin digestion. Twenty-five peptide components of the proteome (including fiber) with greater than 0.25-0.5% contribution to the protein content of the virus were identified and characterized. Fiber was confirmed to be partially glycosylated (both the non-glycosylated and the monoglycosylated states were identified), and two proteins were isolated and identified as phosphorylation derivatives, namely protein V (non-phosphorylated and monophosphorylated) and protein IIIa (mono- and diphosphorylated). This new analytical tool proved to be very useful not only for refining our current knowledge of the polypeptide repertoire of purified infectious virions but also for monitoring and very rapidly identifying structural modifications resulting from changes in the manufacturing process. It was also used successfully for the characterization of various adenoviral constructs.

Adenoviridae↗

PubMed2000

An improved anion-exchange HPLC method for the detection and purification of adenoviral particles.

We have developed an anion-exchange high-performance liquid chromatography (HPLC) method using Q Sepharose XL (Amersham Pharmacia Biotech) as adsorbent to analyze samples containing adenovirus. This method has several major advantages over the HPLC method previously described for quantitating particles, namely (1) a >10-fold improvement in the detection limit of adenovirus in crude preparations; (2) absence of interferences originating from nucleic acids and proteins which usually contaminate crude samples; (3) unprecedented sharpness and symmetry of adenovirus peak, rendering the identification of the viral peak unambiguous, even in extremely crude and dilute preparations; and (4) no enzymatic treatment required even for crude samples. This assay was used to quantitate particles in samples taken at the transfection and amplification stages of production of various recombinant adenovirus, and in cultures of wild-type adenovirus of different serotypes. A modification of this analytical method was also developed for the purification of infectious adenovirus particles, including fiber-modified and third-generation recombinant viruses, giving highly purified preparations from low-titer crude lysates with an excellent overall recovery (50-74%).

Adenoviridae↗

PubMed1987

Prognostic value of response after three MOPP cycles in Hodgkin's disease--stage III and IV.

Sixty-eight patients with Hodgkin's disease stage III and IV were evaluated after three out of six MOPP cycles. At that time, 46 (68%) were classified as early responders and 22 as slow responders. The criteria of response were: disappearance of B symptoms, decrease in the size of the largest lymph nodes (by more than 50%) and significant reduction (more than 20%) of mediastinal enlargement. Out of 43 early responders, 38 were in complete remission after six MOPP cycles and only five out of 22 slow responders. Such an early response is only related to the absence of B symptoms at the time of diagnosis (p less than 0.05). The survival curves of early responders and slow responders were significantly different (p less than 0.02). A rapid erythrocyte sedimentation rate (ESR) (greater than 50 mm) was the most frequently abnormal sign found in the group not responding after three MOPP cycles (p less than 0.0001). Such a significant prognostic value of early response is observed for stage III but not for stage IV patients. We conclude that early clinical response after three MOPP cycles is a good prognostic factor which must be kept in mind in the formulation of the therapeutic regimen for Hodgkin's disease stage III and IV.

Antineoplastic Combined Chemotherapy Protocols↗