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PubMedDate not supplied

Simultaneous determination of water and enediols or thiols in chemical products and drugs not amenable to direct Karl Fischer titration.

A method proposed for determining water and enediols or thiols is based on consecutive titration of the enediols or thiols by a novel reagent and of water by the conventional Karl Fischer reagent in the same cell. The time for both titrations is 8-20 min. The novel reagent consists of iodine, sodium acetate as a base, and potassium iodide in a nonaqueous solvent system. The method is applicable for quality control of chemical products and drugs during their production and trade.

Ascorbic Acid↗
PubMed2000

Seizure threshold in ECT: II. Dose titration vs age and half age methods.

Seizure threshold determination is of crucial importance in optimizing electrical stimulus dosage at electroconvulsive therapy (ECT). We measured initial seizure threshold by means of Srinakharinwirot University titration schedule in 106 patients with schizophrenia or schizoaffective disorder, receiving bilateral ECT. Seizure threshold was approximately 106 millicoulombs on average, and varied 5-fold across patients. Seizure threshold was directly related to age, but inversely related to motor seizure duration. Comparisons of stimulus charge were done with the Age and Half age methods. By using the Half age method, 68 per cent of patients would have seized at the first stimulation and resulted in a closer mean charge to dose-titration method than the Age method. The results may have important clinical implications for stimulus dosing strategy in ECT.

Adolescent↗
PubMed2000

Treatment, airway and compliance effects of a titratable oral appliance.

STUDY OBJECTIVES: To measure the effects of a titratable anterior mandibular repositioner on airway size and Obstructive Sleep Apnea (OSA) and to evaluate its compliance. DESIGN: Before and after insertion sleep studies were obtained in a total of 38 OSA patients of varying severity from three different sites. Covert compliance was measured by means of a newly-developed, miniaturized, temperature-sensitive, imbedded monitor. Validity testing was completed in six adult volunteers who wore monitors imbedded into small acrylic appliances. MEASUREMENTS AND RESULTS: The mean RDI before treatment was 32.6 (SEM 2.1) and after the insertion of the appliance, the RDI was reduced to 12.1 (SEM 1.7, p<0.001). RDI was reduced to less than 15/hour in 80% of a group of moderate OSA patients (RDI 15 to 30) and in 61% of a group of severe OSA patients (RDI > 30) with respect to baseline RDI. Fiber optic video endoscopy was performed on 9 OSA patients with and without the appliance. No significant differences in hypopharynx or oropharynx cross sectional areas were found, but at the level of the velopharynx, the airway size was significantly increased (p<0.05). The index of agreement was 0.99 between the monitor clock time and the subject's log sheets. Compliance data from eight OSA subjects instructed to wear the appliance during sleep indicated that it was worn for a mean of 6.8 hours with a range of 5.6 to 7.5 hours per night. CONCLUSION: The titratable adjustable mandibular advancement appliance, made from thermoelastic acrylic, significantly reduces RDI in moderate to severe OSA patients, has a direct effect on airway size and is well worn throughout the night.

Adult↗
PubMed2000

Indwelling temporary retrobulbar catheter for long-lasting titratable local anesthesia.

OBJECTIVE: To evaluate an indwelling temporary retrobulbar catheter for repeatable injections of local anesthetics for long-lasting and titratable retrobulbar anesthesia in intraocular surgery. PARTICIPANTS: The prospective clinic-based study included 153 patients who underwent vitreoretinal surgery (n=111) or buckling procedures with cryocoagulation (n=34). The mean duration of surgery was 84.7 +/- 49.5 minutes (range, 25-310 minutes). Using commercially available retrobulbar needles with a diameter of 0.60 or 0.80 mm and a length of 38 mm, 5 mL of 2% mepivacaine hydrochloride was injected. Through the same needle, a 28-gauge commercially available flexible catheter was introduced into the retrobulbar space. The needle was withdrawn and the catheter was fixed. When the patients started to feel pain during surgery, 2 mL of mepivacaine hydrochloride was reinjected through the catheter. RESULTS: Ten to 240 minutes after the start of the operation, 96 patients needed an intraoperative reinjection of mepivacaine after which they felt comfortable again. Forty-two patients needed a second reinjection of mepivacaine 30 to 270 minutes after the start of the operation, and 13 patients needed a third reinjection 45 to 145 minutes after the start of surgery. Removal of the catheter after surgery was unremarkable. No infections were observed. Microbiologic examination results of the catheter tip were negative for organisms. Diplopia or other motility problems were not detected. Introduction and fixation of the catheter took less than 5 minutes in all patients. CONCLUSIONS: An indwelling temporary retrobulbar catheter for repeatable intraoperative injections of local anesthetics is simple, effective, and useful, and in comparison with general anesthesia, it is a time-saver for long-lasting and titratable local anesthesia in intraocular surgery. Arch Ophthalmol. 2000;118:996-1000

Aged↗
PubMed1975

[Laboratory procedures in adenoviruses. II. Sensitivity of various cell cultures as determined by endpoint titration (author's transl)].

The sensitivity of human embryonic kidney (HEK), human amnion (HAm) and HeLa cells for human adenoviruses was investigated by means of endpoint titrations of 13 prototype strains and numerous original specimens from patients. Prototypes and original specimens showed the same behavior. Adenoviruses of subgrouppp III produced nearly identical titers in all 3 cell cultures, while for subgroup I HAm cells showed a 10- to 100-fold lower titer. On the other hand, HAm cells are nearly as sensitive as HEK cells for type 8, whereas HeLa cells are less sensitive. For other viruses of subgroup II and for subgrou IV, HAm (for type 12 also HeLa) cells are less sensitive than HEK cells. Out of three HeLa cell strains tested the Bristol strain was inferior to the other two in its sensitivity. Concerning the speed of the CPE development, HEK cells are superior for all types, the difference being greatest for subgroup I towards HAm and HeLa and for type 8 towards HeLa cells. The length of incubation necessary for the appearance of CPE even with minimal amounts of virus is 40 days for type 8 in all kinds of cell cultures, whereas for adenoviruses of sub-groups I and III, which are predominantly isolated in the routine laboratory, 25 days for HEK and 30 days for HAm and HeLa cells may suffice in most cases. When endpoint titrations are compared with titers obtained by immunofluorescence, it appears that this technique may be applied as a screening method; thus long incubation periods of negative specimens can be saved. The amounts of infectious virus present in original specimens are reported; the highest quantity was found in specimens containing subgroup I viruses.

Adenoviridae↗
PubMed2000

Titration study of MUSE (Medicated Urethral System for Erection) in erectile dysfunction.

PURPOSE: We assessed the erectile responses and adverse reactions to prostaglandin E1 delivered via the medicated urethral system for erection (MUSE) in a titration study to determine optimal dose. METHODS: Sixty-four patients with erectile dysfunction underwent in-office testing with MUSE to determine erectile response. Following thorough instructions, patients were taught how to use MUSE themselves. The titration study started with a dose of 125 micrograms, and increased to 250 micrograms, 500 micrograms, and finally 1,000 micrograms. In patients who had an erectile response, erection scoring, color duplex Doppler study, blood pressure monitoring, recording of subjective complaints, and repeated laboratory examinations were performed to evaluate the positive and adverse effects of MUSE. RESULTS: Forty-three of the 64 patients achieved a maximal erection with MUSE, as shown by systolic peak flow velocities in the deep penile arteries of greater than 27 cm/s on Doppler ultrasonography. One patient was unsatisfied with his erectile response and dropped out of the study. Of the 42 patients who completed the study, most (35) were satisfied with the response achieved at the higher doses of 500 micrograms and 1,000 micrograms. A modified soft rubber band was needed to achieve a satisfactory erectile response in 18 patients. Only four patients experienced serious urethral burning during MUSE application. CONCLUSIONS: MUSE was effective and safe in most patients with erectile dysfunction in this study. For patients not satisfied with the extent of penile rigidity achieved with MUSE, the use of a modified soft rubber band for erectile assistance, as well as a program for improved patient education, may help to achieve a better erectile response and facilitate compliance with treatment regimens at home.

Adult↗
PubMed1992

Protein sequences and redox titrations indicate that the electron acceptors in reaction centers from heliobacteria are similar to Photosystem I.

Photosynthetic reaction centers isolated from Heliobacillus mobilis exhibit a single major protein on SDS-PAGE of 47 000 Mr. Attempts to sequence the reaction center polypeptide indicated that the N-terminus is blocked. After enzymatic and chemical cleavage, four peptide fragments were sequenced from the Heliobacillus mobilis apoprotein. Only one of these sequences showed significant specific similarity to any of the protein and deduced protein sequences in the GenBank data base. This fragment is identical with 56% of the residues, including both cysteines, found in highly conserved region that is proposed to bind iron-sulfur center Fx in the Photosystem I reaction center peptide that is the psaB gene product. The similarity to the psaA gene product in this region is 48%. Redox titrations of laser-flash-induced photobleaching with millisecond decay kinetics on isolated reaction centers from Heliobacterium gestii indicate a midpoint potential of -414 mV with n = 2 titration behavior. In membranes, the behavior is intermediate between n = 1 and n = 2, and the apparent midpoint potential is -444 mV. This is compared to the behavior in Photosystem I, where the intermediate electron acceptor A1, thought to be a phylloquinone molecule, has been proposed to undergo a double reduction at low redox potentials in the presence of viologen redox mediators. These results strongly suggest that the acceptor side electron transfer system in reaction centers from heliobacteria is indeed analogous to that found in Photosystem I. The sequence similarities indicate that the divergence of the heliobacteria from the Photosystem I line occurred before the gene duplication and subsequent divergence that lead to the heterodimeric protein core of the Photosystem I reaction center.

Amino Acid Sequence↗
PubMed2001

Titrated oral misoprostol solution--a new method of labour induction.

BACKGROUND: Misoprostol, a cheap, stable, orally active prostaglandin analogue, is effective for labour induction when administered either vaginally or orally, but uterine hyperstimulation and rupture have been reported. Previous studies of oral misoprostol for labour induction have used fixed dosages 3-6-hourly. OBJECTIVES: To develop a new method of misoprostol use for labour induction using very small, frequent, titrated oral dosages, and to pilot effectiveness. STUDY DESIGN: Open clinical pilot study. SETTING: Coronation Hospital, an academic hospital in Johannesburg, South Africa. METHODS: We developed a method using 2-hourly titrated misoprostol doses commencing with 20 micrograms, increased after three doses to 40 micrograms. To administer such small doses we dissolved one misoprostol tablet in 200 ml water. A pilot study of this method was undertaken in 25 women with various indications for induction of labour. RESULTS: Eighteen women (72%) delivered vaginally within 32 hours of induction and two women developed uterine hyperstimulation. The caesarean section rate was 20%. CONCLUSIONS: Women may respond to much smaller dosages of misoprostol than are currently in use. A multicentre randomised trial of this method is underway. We emphasise the dangers inherent in the current unregistered use of misoprostol in clinical practice.

Administration, Oral↗
PubMed1979

Effects of morphine, pentazocine and cyclazocine alone and in combination with naloxone on electric shock titration in the squirrel monkey.

The effects of morphine, pentazocine and cyclazocine were examined on a discrete-trial shock titration procedure. Monkeys received continuous shock during 15-sec shock periods. If the monkey did not respond during the shock period, shock remained on for 15 sec and then increased by one increment on the next 15-sec shock period. If five responses were made during the shock period, the shock was immediately terminated for 15 sec during which the chamber was dark (time out). After the 15-sec time out period, the shock resumed at the next lower intensity. Morphine, pentazocine and cyclazocine altered patterns and rates of responding similarly. At a low dose, pentazocine, cyclazocine and morphine decreased median shock levels and increased rates of responding in the presence and in the absence of shock (i.e., during time out). These effects were observed over a wider dose range with pentazocine and cyclazocine than with morphine; moreover, decreases in median shock level and increases in rates of responding in the absence of shock were of greater magnitude after pentazocine and cyclazocine than after morphine. At higher doses, morphine, pentazocine and cyclazocine increased median shock levels and decreased rates of responding in the absence of shock. Rates of responding in the presence of shock were either unchanged or decreased very slightly, suggesting that increases in the intensity at which shock is maintained under shock titration procedures is not necessarily due to decreases in rates of responding. In contrast, naloxone had very little behavioral effect when administered alone. The effects of morphine were antagonized by a dose of naloxone as low as 0.01 mg/kg, whereas higher doses of naloxone were required to antagonize the effects of pentazocine and cyclazocine.

Animals↗
PubMedDate not supplied

Determination of water (moisture) and dry matter in animal feed, grain, and forage (plant tissue) by Karl Fischer titration: collaborative study.

A Karl Fischer method for determining water (dry matter) in animal feed and forages was collaboratively studied. Water was extracted from animal feed or forage material into methanol-formamide (1 + 1) directly in the Karl Fischer titration vessel by high-speed homogenization. The water was titrated at 50 degrees C with one-component Karl Fischer reagent based on imidazole. Ten blind samples were sent to 9 collaborators in the United States, Canada, and Germany. The within-laboratory relative standard deviation (repeatability) ranged from 1.14 to 6.99% for water or from 0.09 to 0.56% for dry matter. Among-laboratory (including within-) relative standard deviation (reproducibility) ranged from 5.35 to 10.73%, or from 0.44 to 0.77% for dry matter. The authors recommend that the method be adopted as Official First Action by AOAC INTERNATIONAL. A comparable alternative extraction procedure using boiling methanol is also recommended for Official First Action.

Animal Feed↗
PubMedDate not supplied

[Titration and dosage of gabapentin].

INTRODUCTION: Gabapentin (GBP) is a new anti epileptic drug which is indicated in partial epilepsy as either monotherapy or additional therapy. Unlike most anti epileptic drugs, GBP can be rapidly titrated. DEVELOPMENT: A recent double blind trial has shown that treatment with GBP may start with 900mg from the first day (300 mg every 8 hours). This dose is sufficient to be effective as monotherapy in patients with partial epilepsy of recent onset. It is also known that in patients with drug resistant epilepsy high doses of anti epileptic drugs are often necessary. In the clinical trials carried out before gabapentin was put on the market, the doses used were generally low (almost always below 1,800 mg/day). However, recent experience has shown that doses of up to 4,800 mg/day markedly increase the efficacy without significant increase in the rate of adverse effects. CONCLUSIONS: Recent data suggest that GBP may be rapidly titrated and high doses of GBP show greater efficacy with no increase in adverse effects, so they are advisable in drug resistant patients.

Acetates↗
PubMed2002

[Construction, packaging and titration of recombinant adeno-associated virus vectors contaning antitumor genes].

OBJECTIVE: To construct, package, and titrate vectors that express antitumor genes using adeno-associated virus (AAV) containing human alpha-fetoprotein (AFP) promoter. METHODS: Recombinant AAV vectors were constructed by blunted ligation of plasmids rAAV-AFP-GFP and pTR-UF5 and p16 cDNA and p21 cDNA. Packaging cell lines, 293 and C12 cells, were transfected with rAAV vectors, plasmid PspRC72, and adenovirus cosmid pAdc with the help of LipofectAMINE and then infected by wild adenovirus 48 hours later. The total viral particle titre was measured by PCR. Electron microscopy was used to observe the morphology of rAAV. C12 cells were infected with rAAV and wild adenovirus (MOI 10) and the titre of infectious virus was measured. by RCA method. Hepatocellular carcinoma cells were cultured and infected with rAAV containing green fluorescent protein (GFP), the infectious rate was observed 48 hours later. RESULTS: Recombinant vectors, rAAV-AFP-p16, rAAV-AFP-p21, rAAV-CMV-p16, and rAAV-CMV-p21, were constructed and verified by DNA sequencing and enzyme digestion. The total viral titre was 10(13) to 10(14)/ml. The titre of infectious rAAV containing GFP was 5 x 10(10)/ml. Electron microscopy showed that the rAVV was round and plaqued with a diameter between 20 and 30 nm. When the MOI was 100, the infectious rate of hepatocellular carcinoma cells was at least 70%. Four rAAV vectors carrying p16 or p21 genes have been constructed. rAAV packaging and titration methods were developed to produce highly-purified AAV stocks. These approaches help in research of gene therapy in liver cancer.

Cell Line↗
PubMed2002

Effects of remifentanil infusion bis-titrated on early recovery for obese outpatients undergoing laparoscopic cholecystectomy.

BACKGROUND: In obese patients functional residual capacity comes down with a possible hypoxemia in postoperative period. In fact many studies has been begun to determine optimum ventilation regulation and the best position for these patients, but the question has not been solved. As remifentanil can reduce of 50% the inhalatory anaesthetic request and reverse Trendelemburg position is extremely useful for these patients, we hypothesized that use of a continuous remifentanil infusion during balanced anaesthesia with sevoflurane, BIS-titrated, associated to reverse Trendelem-burg position could facilitate emergence from anaesthesia in obese patients undergoing laparascopic cholecystectomy. METHODS: We studied 40 patients, ASA II class, with higher than 30 kg/m2 body mass index, undergoing to laparoscopic cholecystectomy. All the patients, in operating room, received standard monitoring and BIS sensor application. All the data were continuously collected. Induction of anaesthesia has been with a refracted bolus in 120 sec of remifentanil 1 mg/kg, followed by propofol 1.5 mg/kg and cisatracurium 0.15 mg/kg. Maintenance of anaesthesia has been by balanced anaesthesia with continuous remifentanil infusion, ventilating patients with sevoflurane in oxygen and air. Patients were randomized into two homogenous groups. Into the control group has been varied sevoflurane inspiratory concentration on the ground of BIS value (from 0.3% to 3%), while into remifentanil group remifentanil infusion has been varied (from 0.25 to 2 mg/kg/min) to maintain medium pressure values which don't stray more than 25% from basal values, on the ground of BIS values. On pre-established times of operation, respiratory mechanics and blood gases were examined. RESULTS: As it was to expect, sevoflurane concentration variations resulted very high in control group compared to remifentanil group. Awakening time, extubation, orientation and transfer to PACU (postanaesthesia care unit) resulted significantly lower than remifentanil group. CONCLUSIONS: Concluding, remifentanil infusion, BIS-titrated, facilitates awakening times from balanced anaesthesia with Sevoflurane in obese patients, submitted to laparoscopic cholecystectomy.

Adult↗
PubMed2002

Denitrifying activity measurements using an anoxic titration (pHstat) bioassay.

An anoxic titrimetric test was investigated for measuring denitrifying activity in an activated sludge system. The method measures the amount of acid that is required to maintain the pH set-point value in a batch denitrification experiment. An iterative algorithm was implemented to extract nitrate uptake rate (NUR) data from titration data, since the accumulation and depletion (stripping) of reaction by-products HCO3- and CO2 affects the direct calculation of denitrifying activity from titration data. This method was performed using an automatic pH-stat acid dosing system, and the data were analysed using the simulation software package, AQUASIM.

Automation↗
PubMedDate not supplied

[Titration of SH-groups of histone H3 in a DNP preparation of normal and neoplastic animal cells with a mercury-containing spin marker and with a DTNB preparation].

DNP samples isolated from the cells of calf thymus and Ehrlich ascite carcinoma of mice were examined. SH-groups of histone H3 of chromatin from these cells were titrated with mercury-containing spin label and with DTNB under joint action of different salt and sarcosyl concentrations on DNP. The results revealed differences in accessibility and titration of histone H3 SH-groups in DNP of normal and tumor cells with DTNB, as well as in molecular dynamics of the mercury-containing spin label introduced to these SH-groups.

Animals↗
PubMed1960

Titration of vaccinia virus by intravenous injection of chick embryos.

The final test of a smallpox vaccine is its capacity to prevent the disease from developing in inoculated individuals. This capacity, however, cannot be measured directly, so that other methods of assessing the efficacy of vaccine have had to be developed. A laboratory method-pock counting on the chorio-allantoic membrane of chick embryos-has recently been shown to provide a reasonably reliable estimate of the number of infective units in a given vaccine. In this paper, the author compares this pock-counting method with another method-titration by intravenous injection of chick embryos. He concludes that, although the reproducibility of titrations by intravenous injection compares very favourably with that obtained by chorio-allantoic inoculation, the former method would not be advantageous for the assay of vaccines, since it is very time-consuming and since differences in virulence might obscure comparisons between the efficacy of vaccines.

Animals↗
PubMed1961

A comparison of the rabbit scarification technique with titrations in cell cultures for the potency assay of smallpox vaccine.

Effective tissue culture methods have been developed for the titration of smallpox vaccines, and it seemed appropriate to study their application as methods for assaying the potency of commercial smallpox vaccines. Thirty-four commercial smallpox vaccines were assayed for potency by titration in both rabbit and monkey kidney cell test systems and by the traditional rabbit scarification method.Approximately 85% of the vaccines showed acceptable potency by the rabbit scarification method. Comparative studies between all three test systems showed that consistent results could be obtained with 79% of all vaccines tested. A similar degree of correlation with the same vaccines was shown by a direct comparison of infectivity titres between the two animal tissue cell systems.Certain discrepancies in the potency of individual vaccines and difficulties inherent in cell culture assay were noted. In view of these deficiencies, it was concluded that further comparison of the rabbit scarification and cell culture methods with vaccines of borderline potency should be studied, and that, until the properties of smallpox vaccines have been compared in the rabbit test, cell culture and man, the cell culture methods should be neither accepted nor rejected.

Animals↗