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Extended Duration (extended + duration)

Distribution by Scientific Domains

Medical Sciences	64%
Life Sciences	28%

Selected Abstracts

Climate Variability in Regions of Amphibian Declines

CONSERVATION BIOLOGY, Issue 4 2001
Michael A. Alexander
The reanalysis system merges observations from airplanes, land stations, satellites, ships, and weather balloons with output from a weather-forecast model to create global fields of atmospheric variables. Station data consisted of temperature and precipitation measured with thermometers and rain gauges at fixed locations. Temperatures were near normal in Colorado when the amphibian declines occurred in the 1970s, whereas in Central America temperatures were warmer than normal, especially during the dry season. The station data from Puerto Rico and Australia indicated that temperatures were above normal during the period of amphibian declines, but reanalysis did not show such a clear temperature signal. Although declines occurred while the temperature and precipitation anomalies in some of the regions were large and of extended duration, the anomalies were not beyond the range of normal variability. Thus, unusual climate, as measured by regional estimates of temperature and precipitation, is unlikely to be the direct cause of amphibian declines, but it may have indirectly contributed to them. Previous researchers have noted that the declines appear to have propagated from northwest to southeast from Costa Rica to Panama and from southeast to northwest in Queensland, Australia. Wind has the potential to transport pathogens that cause amphibian mortality. The mean direction of the near-surface winds tended to parallel the path of amphibian declines from July,October in Central America and from May,July in Australia. The wind direction was highly variable, however, and the propagation rate of amphibian declines was much slower than the mean wind speed. In addition, the most likely pathogen is a chytrid fungus that does not produce desiccation-resistant spores. Thus, if wind is involved in the propagation of amphibian declines, it is through a complex set of processes. Resumen: Exploramos la relación entre las declinaciones de anfibios y las variaciones climáticas en Colorado, E.U.A., Puerto Rico, Costa Rica/Panamá y Queensland, Australia por medio de dos fuentes de información: resultados "sistema de reanálisis" del Centro Nacional de Predicción Ambiental y datos de estaciones área-promedio. El sistema de reanálisis combina observaciones de aeroplanos, estaciones terrestres, satélites, barcos y globos climatológicos, con resultados de un modelo de predicción climatológica para crear campos globales de variables atmosféricas. Los datos de estaciones fueron de temperatura y precipitación medidos con termómetros y pluviómetros en localidades fijas. Las temperaturas fueron casi normales en Colorado cuando ocurrieron las declinaciones en la década de 1970, mientras que las temperaturas en Centro América fueron mayores a lo normal, especialmente durante la época de sequía. Los datos de estaciones en Puerto Rico y Australia indicaron que la temperatura fue mayor a la normal durante el período de declinación de anfibios, pero un nuevo análisis no mostró una señal de temperatura tan clara. Aunque las declinaciones ocurrieron mientras las anomalías de temperatura y precipitación fueron grandes y de duración prolongada en algunas de las regiones, las anomalías no rebasaron el rango de variabilidad normal. Por lo tanto, es poco probable que el clima inusual, medido por estimaciones regionales de temperatura y precipitación, sea la causa directa de las declinaciones de anfibios, pero pudo haber contribuido indirectamente a ellas. Investigaciones previas notan que las declinaciones parecen haberse propagado de noroeste a sureste de Costa Rica a Panamá y de sureste a noreste en Queensland, Australia. El viento tiene el potencial de transportar patógenos que causan mortalidad de anfibios. La dirección promedio de los vientos superficiales tendió a ser paralela al camino de las declinaciones de anfibios de julio a octubre en Centro América y de mayo a julio en Australia. Sin embargo, la dirección del viento fue altamente variable y la tasa de propagación de declinaciones de anfibios fue mucho más lenta que la velocidad promedio del viento. Adicionalmente, el patógeno más probable es un hongo quítrido que no produce esporas resistentes a la desecación. Por tanto, si el viento está implicado en la propagación de declinaciones de anfibios, lo es por medio de un complejo conjunto de procesos. [source]

The structure and mode of action of different botulinum toxins

EUROPEAN JOURNAL OF NEUROLOGY, Issue 2006
J. O. Dolly
The seven serotypes (A,G) of botulinum neurotoxin (BoNT) are proteins produced by Clostridium botulinum and have multifunctional abilities: (i) they target cholinergic nerve endings via binding to ecto-acceptors (ii) they undergo endocytosis/translocation and (iii) their light chains act intraneuronally to block acetylcholine release. The fundamental process of quantal transmitter release occurs by Ca2+ -regulated exocytosis involving sensitive factor attachment protein-25 (SNAP-25), syntaxin and synaptobrevin. Proteolytic cleavage by BoNT-A of nine amino acids from the C-terminal of SNAP-25 disables its function, causing prolonged muscle weakness. This unique combination of activities underlies the effectiveness of BoNT-A haemagglutinin complex in treating human conditions resulting from hyperactivity at peripheral cholinergic nerve endings. In vivo imaging and immunomicroscopy of murine muscles injected with type A toxin revealed that the extended duration of action results from the longevity of its protease, persistence of the cleaved SNAP-25 and a protracted time course for the remodelling of treated nerve,muscle synapses. In addition, an application in pain management has been indicated by the ability of BoNT to inhibit neuropeptide release from nociceptors, thereby blocking central and peripheral pain sensitization processes. The widespread cellular distribution of SNAP-25 and the diversity of the toxin's neuronal acceptors are being exploited for other therapeutic applications. [source]

Long-lasting infiltration anaesthesia by lidocaine-loaded biodegradable nanoparticles in hydrogel in rats

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2009
Q.-Q. YIN
Background: Infiltration of a long-lasting anaesthetic is helpful during the post-operative period. The recently developed local drug delivery system, biodegradable nanoparticles in a thermo-sensitive hydrogel (nanogel system), may possibly provide an extended duration of drugs. Therefore, we evaluated whether prolonged infiltration anaesthesia could be achieved by loading lidocaine into this delivery system. Methods: Thirty male rats were randomized into five groups of six rats each: saline; 2% hydrochloride lidocaine solution; lidocaine-loaded nanogel system and its compositing formulations, namely lido,nano gel; lido,nano; and lidogel. Durations of local anaesthesia with subcutaneously injected agents were measured by tail flick latency tests in a randomized, blind fashion. Results: Lido,nano gel produced effective anaesthesia for 360±113 min, compared with 150±33 min by lidogel, 180±37 min by lido,nano, and 110±45 min by lidocaine solution (P<0.001, means±SD), and elicited complete sensory blockade for 300±114 min, compared with 75±37 min by lidogel, 105±53 min by lido,nano, and 60±33 min by lidocaine solution (P<0.001, means±SD) without severe skin/systemic toxicity. Conclusion: Lidocaine-loaded biodegradable nanoparticles in hydrogel produced prolonged infiltration anaesthesia in rats without severe toxicity, indicating a possible way to develop long-lasting local anaesthetics. [source]

Breeding patterns of Arvicanthis neumanni in central Tanzania

AFRICAN JOURNAL OF ECOLOGY, Issue 3 2008
A. W. Massawe
Abstract The breeding pattern of the grass rat, Arvicanthis neumanni, was investigated in central Tanzania in 2002/2003. Nine hundred and forty-seven animals were captured in three age groups: juveniles, sub adults and adults. These age groups were present in the population for an extended duration, but there was an increase in the number of sexually active individuals and juveniles 2,3 months after the onset of the rains (December 2002,May 2003). A peak in reproductive activity occurred between January and April. Litter size ranged between 5.58 ± 0.42 and 6.1 ± 0.26 in two study sites. There were no significant differences in the number of embryos implanted in the right and left horns of the uterus of pregnant females (t22 = 0, P > 0.05 and t36 = 1.68, P > 0.05, respectively). Sex ratio of A. neumanni was not skewed to either males or females. Breeding was seasonal and seemed to be associated with seasonal variations in primary productivity, which relates to rainfall patterns. Résumé Le schéma de reproduction d'Arvicanthis neumanni a étéétudié dans le centre de la Tanzanie en 2002/2003. On a capturé 947 animaux appartenant à trois groupes d'âge : juvéniles, sub-adultes et adultes. Ces groupes d'âge étaient présents dans la population pendant une longue période, mais il y avait une augmentation du nombre d'individus sexuellement actifs et de juvéniles deux à trois mois après le début des pluies (décembre 2002-mai 2003). Il y eut un pic d'activité sexuelle entre janvier et avril. La taille des portées allait de 5.58 ± 0.42 à 6.1 ± 0.26 dans deux sites étudiés. Il n'y avait pas de différence significative du nombre d'embryons implantés dans les cornes droite et gauche de l'utérus des femelles (t22 = 0, P > 0.05 et t36 = 1.68, P > 0.05 respectivement). Le sex-ratio d'A. neumanni ne favorise ni les mâles, ni les femelles. La reproduction est saisonnière et semble associée aux variations saisonnières de la productivité primaire, liées, elles, aux chutes de pluie. [source]

Effect of dexmedetomidine on the characteristics of bupivacaine in a caudal block in pediatrics

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2009
I. SAADAWY
Background: Dexmedetomidine (DEX) is a highly selective ,2 -adrenoceptor agonist that has been used increasingly in children. However, the effect of caudal DEX has not been evaluated before in children. This prospective randomized double-blinded study was designed to evaluate the analgesic efficacy of caudal DEX with bupivacaine in providing pain relief over a 24-h period. Methods: Sixty children (ASA status I) aged 1,6 years undergoing unilateral inguinal hernia repair/orchidopexy were allocated randomly to two groups (n=30 each). Group B received a caudal injection of bupivacaine 2.5 mg/ml, 1 ml/kg; Group BD received the same dose of bupivacaine mixed with DEX 1 ,g/kg during sevoflurane anesthesia. Processed electroencephalogram (bispectral index score), heart rate, blood pressure, pulse oximetry and end-tidal sevoflurane were recorded every 5 min. The characteristics of emergence, objective pain score, sedation score and quality of sleep were recorded post-operatively. Duration of analgesia and requirement for additional analgesics were noted. Results: The end-tidal sevoflurane concentration and the incidence of agitation were significantly lower in the BD group (P<0.05). The duration of analgesia was significantly longer (P<0.001) and the total consumption of rescue analgesic was significantly lower in Group BD compared with Group B (P<0.01). There was no statistically significant difference in hemodynamics between both groups. However, group BD had better quality of sleep and a prolonged duration of sedation (P<0.05). Conclusion: Caudal DEX seems to be a promising adjunct to provide excellent analgesia without side effects over a 24-h period. It has the advantage of keeping the patients calm for a prolonged time. Implications statement: Caudally administered DEX (1 ,g/kg), combined with bupivacaine, was associated with an extended duration of post-operative pain relief. [source]

Late Quaternary deglaciation and climate history of the Larsemann Hills (East Antarctica)

JOURNAL OF QUATERNARY SCIENCE, Issue 4 2004
Elie Verleyen
Abstract The Late Quaternary climate history of the Larsemann Hills has been reconstructed using siliceous microfossils (diatoms, chrysophytes and silicoflagellates) in sediment cores extracted from three isolation lakes. Results show that the western peninsula, Stornes, and offshore islands were ice-covered between 30,000,yr,BP and 13,500,cal.,yr,BP. From 13,500,cal.,yr,BP (shortly after the Antarctic Cold Reversal) the coastal lakes of the Larsemann Hills were deglaciated and biogenic sedimentation commenced. Between 13,500 and 11,500,cal.,yr,BP conditions were warmer and wetter than during the preceding glacial period, but still colder than today. From 11,500 to 9500,cal.,yr,BP there is evidence for wet and warm conditions, which probably is related to the early Holocene climate optimum, recorded in Antarctic ice cores. Between 9500 and 7400,cal.,yr,BP dry and cold conditions are inferred from high lake-water salinities, and low water levels and an extended duration of nearshore sea-ice. A second climate optimum occurred between 7400 and 5230,cal.,yr,BP when stratified, open water conditions during spring and summer characterised the marine coast of Prydz Bay. From 5230 until 2750,cal.,yr,BP sea-ice duration in Prydz Bay increased, with conditions similar to the present day. A short return to stratified, open water conditions and a reduction in nearshore winter sea-ice extent is evident between 2750 and 2200,cal.,yr,BP. Simultaneously, reconstructions of lake water depth and salinity suggests relatively humid and warm conditions on land between 3000 and 2000,cal.,yr,BP, which corresponds to a Holocene Hypsithermal reported elsewhere in Antarctica. Finally, dry conditions are recorded around 2000, between 760 and 690, and between 280 and 140,cal.,yr,BP. These data are consistent with ice-core records from Antarctica and support the hypothesis that lacustrine and marine sediments on land can be used to evaluate the effect of long-term climate change on the terrestrial environment. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Swimming speed and foraging strategies of New Zealand sea lions (Phocarctos hookeri)

JOURNAL OF ZOOLOGY, Issue 2 2001
D. E. Crocker
Abstract Lactating New Zealand sea lions (Phocarctos hookeri) have recently been reported to be the longest and deepest-diving otariid. An unusually large proportion of dives exceeded a theoretical aerobic dive limit, predicted from estimated oxygen stores and measurements of diving metabolic rate. We investigated swimming speed, a key variable in both the management of oxygen stores and foraging strategies, and its relation to diving behaviour in New Zealand sea lions. Diving behaviour was nearly continuous with short inter-dive intervals. Mean diving swimming speeds ranged from 1.6 to 2.4 m/s. Mean surface swimming speeds ranged from 0.9 to 1.8 m/s and were significantly lower than diving speeds in all subjects. New Zealand sea lions spend significant but variable amounts of time resting at the surface. Diving and swimming speed patterns were consistent with foraging on the benthos. Time in the foraging zone was maintained in deeper dives by increasing dive duration. This increased duration cannot be accounted for by a decreased metabolic rate resulting from slower swimming speeds, as speeds increased with the maximum depth of dives. Patterns of swimming speed and acceleration suggest the use of a gliding phase during descent. For most females, the extended duration of deeper dives did not impact on surface times, suggesting the use of aerobic metabolism. Females exhibited significantly slower swim speeds during the bottom segments of foraging dives than during descent or ascent. These findings suggest that swimming behaviour should be considered a critical component when modelling energetic costs for diving animals. [source]

Managing chronic hepatitis C in the difficult-to-treat patient

LIVER INTERNATIONAL, Issue 10 2007
Nyingi Kemmer
Abstract Patients with chronic hepatitis C virus (HCV) infection and disease-related complications , among them cirrhosis and liver failure , pose a particular management challenge. Some of these patients may fail to respond to current therapy (non-responders), and some are affected so severely that treatment puts them at an unacceptable risk for complications. Treatment with pegylated interferon (peg-IFN) plus ribavirin improves hepatic enzyme levels and eradicates the virus in ,50% of patients; however, a significant number of patients do not respond to therapy or relapse following treatment discontinuation. Several viral, hepatic and patient-related factors influence response to IFN therapy; many of these factors cannot be modified to improve long-term outcomes. Identifying risk factors and measuring viral load early in the treatment can help to predict response to IFN therapy and determine the need to modify or discontinue treatment. Retreatment options for patients who have failed therapy are limited. Retreatment with peg-IFN has been successful in some patients who exhibit an inadequate response to conventional IFN treatment, particularly those who have relapsed. Consensus IFN, another option in treatment-resistant patients, has demonstrated efficacy in the retreatment of non-responders and relapsers. Although the optimal duration of retreatment and the benefits and safety of maintenance therapy have not been determined, an extended duration is likely needed. This article reviews the risk factors for HCV treatment resistance and discusses the assessment and management of difficult-to-treat patients. [source]

Vitamin supplement use among children with Down's syndrome and risk of leukaemia: a Children's Oncology Group (COG) study

PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 3 2008
Cindy K. Blair
Summary Vitamin supplements have been proposed for children with Down's syndrome (DS) with claims of improving cognitive abilities, or immune or thyroid function. Several studies have shown decreased levels of zinc in this population. Because children with DS have a 50-fold increased risk of developing acute leukaemia during the first 5 years of life, we explored the relation between child vitamin and herbal supplement use and the risk of leukaemia in a case-control study. During the period 1997,2002, we enrolled 158 children with DS aged 0,18 years that were diagnosed with acute lymphoblastic leukaemia (ALL) (n = 97) or acute myeloid leukaemia (AML) (n = 61) at participating Children's Oncology Group institutions. We enrolled 173 DS children without leukaemia (controls), selected from the cases' primary care clinic and frequency-matched on age. Data were collected via telephone interviews with mothers of the index child regarding use of multivitamins, zinc, vitamin C, iron and herbal supplements, including age at first use, frequency and duration. Among controls, 57% reported regular multivitamin use (,3 times/week for ,3 months) compared with 48% of ALL cases and 61% of AML cases. We found no evidence of an association between children's regular multivitamin use and ALL or AML (adjusted odds ratios [OR] = 0.94 [95% CI 0.52, 1.70] and 1.90 [0.73, 4.91] respectively). There was a suggestion of an increased risk for AML associated with regular multivitamin use during the first year of life or for an extended duration (ORs = 2.38 [0.94, 5.76] and 2.59 [1.02, 6.59] respectively). Despite being the largest study of DS-leukaemia, our sample size was small, resulting in imprecise effect estimates. Future research should include larger sample sizes as well as a full assessment of diet including vitamin supplementation to adequately examine the relation between nutritional status and childhood leukaemia. [source]

High levels of CXCL8 in tracheal aspirate samples taken at birth are associated with adverse respiratory outcome only in preterm infants younger than 28 weeks gestation

PEDIATRIC PULMONOLOGY, Issue 3 2007
Jozef De Dooy PhD
Abstract We investigated the relation between perinatal endotracheal colonization, the associated cytokine response and respiratory outcome in ventilated preterm neonates. Between September 1999 and March 2002, a cohort of 141 neonates with a gestational age <31 weeks requiring ventilation directly after birth, were followed prospectively. All were admitted to the Neonatal Intensive Care Unit, University Hospital of Antwerp, Belgium. A tracheal aspirate (TA) sample was collected soon after birth and was processed for microbiological examination, leukocyte count, and cytokine analysis (interleukines [IL] IL-1,, IL-6, CXCL8 (formerly called IL-8), IL-10, IL-12p70 and tumor necrosis factor alpha [TNF-,]). Together with the prospectively registered patient's comorbidities and severity of disease, these inflammatory parameters were analyzed in a multivariate Cox proportional hazards model with time of extubation and duration of oxygen therapy as main outcome measures. Of the 141 patients included, 31 (22%) died before discharge from the unit and 37 (26%) had a positive TA culture. Independent predictors of duration of mechanical ventilation were: gestational age <28 weeks, degree of respiratory distress syndrome (RDS) at birth, significant patent ductus arteriosus (PDA), the SNAP-score, and high levels of CXCL8 (>4,153 pg/ml) in TA only in neonates with a gestational age <28 weeks. Variables associated with extended duration of oxygen therapy were gestational age <28 weeks, birth weight <1,000 g, degree of RDS at birth, and duration of mechanical ventilation. Pediatr Pulmonol. 2007; 42:193,203. © 2007 Wiley-Liss, Inc. [source]

Reproductive adaptations to a large-brained fetus open a vulnerability to anovulation similar to polycystic ovary syndrome

AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 3 2003
Deborah K. Barnett
During the ovarian or menstrual cycle, prior to ovulation, many female primates exhibit a relatively prolonged follicular phase and terminate the postovulatory luteal phase with menstrual bleeding. The prolonged follicular phase is a trait that distinguishes primate from nonprimate species. It enables extended estrogen-induced proliferation and growth of the uterine endometrium prior to progesterone-induced maturation during the luteal phase to accommodate a potential pregnancy with a rapidly invading placenta. Progressive development of both an extended duration of estrogen-induced, preimplantation endometrial proliferation and a rapidly invading placenta across the Primate order may well have been necessary to accommodate differentiation and growth of an increasingly large fetal brain. Prolongation of the follicular phase in primates has also led to the isolation of the final stages of follicle selection (growth deviation of the dominant follicle from its contemporaries) solely within the follicular phase and thus outside the protection of luteal phase progesterone inhibition of pituitary luteinizing hormone (LH) secretion. Such primate reproductive characteristics put the latter stages of ovarian follicle selection at risk of exposure to excessive pituitary secretion of LH. Excessive secretion of LH during follicle selection could result not only in impaired follicle development, excessive ovarian androgen secretion, and ovulation failure, but also in excessive estrogenic stimulation of the uterine endometrium without intervening menstrual periods. Such reproductive abnormalities are all found in a single, prevalent infertility syndrome afflicting women in their reproductive years: polycystic ovary syndrome (PCOS). We propose that successful female reproductive adaptations to accommodate the growth demands of large-brained primate fetuses have facilitated a particular vulnerability of higher primates to hypergonadotropic disruption of ovulatory function, as found in PCOS. Am. J. Hum. Biol. 15:296,319, 2003. © 2003 Wiley-Liss. [source]

Pharmacokinetics and tolerability of intranasal diazepam and midazolam in healthy adult volunteers

ACTA NEUROLOGICA SCANDINAVICA, Issue 5 2009
V. D. Ivaturi
Objective,,, The purpose of this pilot study was to determine the pharmacokinetics and tolerability of an investigational diazepam (DZP) formulation and a parenteral midazolam (MDZ) formulation following intranasal (i.n.) administration for the efficient treatment of seizure emergencies. Methods,,, Each subject received 5 mg of DZP and MDZ via both i.n. and intravenous routes in a four-way, randomized crossover trial. Blood samples were collected over 48 h. DZP and MDZ concentrations were measured using HPLC. Using analog scales, subjects rated tolerability (0 = no change from normal; 10 = maximum intolerability) and pain (0 = no pain; 4 = extreme pain) prior to and 0, 5, 15, 60 min, and 8 h after administration. Results,,, The Cmax and Tmax values for i.n. DZP and MDZ were 179.2 ng/ml and 28.8 min vs 62.8 ng/ml and 21.6 min, respectively. Immediately following i.n. administration, subjects reported tolerability scores of 6.75 and 6.0, and identical pain scores, 3.2, for DZP and MDZ, respectively. Conclusion,,, Both formulations were rapidly absorbed following i.n. administration with transient discomfort. DZP had a longer half-life, which may result in an extended duration of action. Further studies in large patient populations to evaluate the safety after long term use, efficacy and pharmacokinetics of i.n. DZP are warranted. [source]

The risk of renal impairment in hormone-refractory prostate cancer patients with bone metastases treated with zoledronic acid,

CANCER, Issue 6 2007
William K. Oh MD
Abstract BACKGROUND Bisphosphonates have been used to treat bone metastases in hormone-refractory prostate cancer (HRPC), but certain agents have been associated with renal toxicity. For this observational study, the authors assessed the risk of renal impairment in patients with HRPC who received zoledronic acid from December 1999 to April 2005. METHODS A comprehensive medical records review was performed in a major tertiary oncology center (n = 122 patients). The primary outcome of renal impairment was defined as an increase ,0.5 mg/dL or ,1.0 mg/dL over baseline creatinine value if the baseline value was <1.4 mg/dL or ,1.4 mg/dL, respectively. A risk factor analysis was conducted using the Andersen-Gill extension to the Cox proportional hazards model. RESULTS Renal impairment was observed in 23.8% of patients. The risk of renal impairment increased with an extended duration of zoledronic acid therapy (<6 months, 11.1%; ,24 months, 26.3%) and previous pamidronate treatment (45.5% vs 19.0% for patients with no prior pamidronate). A significantly greater risk of renal impairment was associated with increasing age at zoledronic acid initiation, prior pamidronate use, and a history of renal disease, hypertension, or smoking (P , 0.05). CONCLUSIONS In an outpatient clinic setting, the risk of renal impairment among patients with HRPC who received zoledronic acid was greater than the risk reported previously in clinical trials. Cancer 2007 © 2007 American Cancer Society. [source]

Ocular surface retention time and extensions of TFBUT of a lubricating eye drop

ACTA OPHTHALMOLOGICA, Issue 2007
M IPINAZAR UNDURRAGA
Purpose: The tear film in subjects with ocular dryness is often unstable and incapable of maintaining the protective qualities that are intrinsic to its structure and function. Until recently, lubricating eye drops have provided only transient relief from ocular dryness. The purpose of these studies is to determine if a lubricating eye drop, containing PG/PEG/HP-Guar, will extend ocular protection. Methods: To compare the ocular residence time of lubricating eye drops, subjects with dry feeling eyes were administered a solution of Fluoroscein Isothiocyanate-dextran mixed with a the eye drops. The residence time was measured by a scanning fluorometer. To compare TFBUT, subjects with moderately dry feeling eyes were administered a single drop of a lubricating eye drop. After instillation, TFBUT was measured at 0, 5, 10, 15, 20, 30, 45, 60, and 90 minutes. Results: Tear film retention of the PG/PEG/HP-Guar product was significantly greater than a HPMC and a CMC lubricating eye drop. The product containing PG/PEG/HP-Guar was measured in the tear film as much as 37 minutes post instillation, while the HPMC and CMC drops were only 25 and 23 minutes, respectively. The PG/PEG/HP-Guar tear yielded a significantly greater increase in TFBUT from baseline at 45, 60, and 90 minutes post-installation compared to eyes dosed with a CMC/Glycerin drop. Conclusions: Based on these results, it can be postulated that the extended duration of retention observed with the PG/PEG/HP-Guar tear allows the necessary time for restructuring of the unstable tear film into a more stable tear film. This leads to a long-term tear film stabilization and enhancement of TFBUT and ultimately, extended ocular surface protection [source]