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1.
Psychol Med ; 52(3): 548-573, 2022 02.
Article in English | MEDLINE | ID: mdl-32674747

ABSTRACT

BACKGROUND: Over the past 15 years, there has been substantial growth in web-based psychological interventions. We summarize evidence regarding the efficacy of web-based self-directed psychological interventions on depressive, anxiety and distress symptoms in people living with a chronic health condition. METHOD: We searched Medline, PsycINFO, CINAHL, EMBASE databases and Cochrane Database from 1990 to 1 May 2019. English language papers of randomized controlled trials (usual care or waitlist control) of web-based psychological interventions with a primary or secondary aim to reduce anxiety, depression or distress in adults with a chronic health condition were eligible. Results were assessed using narrative synthases and random-effects meta-analyses. RESULTS: In total 70 eligible studies across 17 health conditions [most commonly: cancer (k = 20), chronic pain (k = 9), arthritis (k = 6) and multiple sclerosis (k = 5), diabetes (k = 4), fibromyalgia (k = 4)] were identified. Interventions were based on CBT principles in 46 (66%) studies and 42 (60%) included a facilitator. When combining all chronic health conditions, web-based interventions were more efficacious than control conditions in reducing symptoms of depression g = 0.30 (95% CI 0.22-0.39), anxiety g = 0.19 (95% CI 0.12-0.27), and distress g = 0.36 (95% CI 0.23-0.49). CONCLUSION: Evidence regarding effectiveness for specific chronic health conditions was inconsistent. While self-guided online psychological interventions may help to reduce symptoms of anxiety, depression and distress in people with chronic health conditions in general, it is unclear if these interventions are effective for specific health conditions. More high-quality evidence is needed before definite conclusions can be made.


Subject(s)
Cognitive Behavioral Therapy , Internet-Based Intervention , Adult , Anxiety/therapy , Cognitive Behavioral Therapy/methods , Depression/therapy , Humans , Psychosocial Intervention , Randomized Controlled Trials as Topic
2.
IBM J Res Dev ; 62(6): 1-9, 2018.
Article in English | MEDLINE | ID: mdl-32154805

ABSTRACT

NAMD (NAnoscale Molecular Dynamics) is a parallel molecular dynamics application that has been used to make breakthroughs in understanding the structure and dynamics of large biomolecular complexes, such as viruses like HIV and various types of influenza. State-of-the-art biomolecular simulations often require integration of billions of timesteps, computing all interatomic forces for each femtosecond timestep. Molecular dynamics simulation of large biomolecular systems and long-timescale biological phenomena requires tremendous computing power. NAMD harnesses the power of thousands of heterogeneous processors to meet this demand. In this paper, we present algorithm improvements and performance optimizations that enable NAMD to achieve high performance on the IBM Newell platform (with POWER9 processors and NVIDIA Volta V100 GPUs) which underpins the Oak Ridge National Laboratory's Summit and Lawrence Livermore National Laboratory's Sierra supercomputers. The Top-500 supercomputers June 2018 list shows Summit at the number one spot with 187 Petaflop/s peak performance and Sierra third with 119 Petaflop/s. Optimizations for NAMD on Summit include: data layout changes for GPU acceleration and CPU vectorization, improving GPU offload efficiency, increasing performance with PAMI support in Charm++, improving efficiency of FFT calculations, improving load balancing, enabling better CPU vectorization and cache performance, and providing an alternative thermostat through stochastic velocity rescaling. We also present performance scaling results on early Newell systems.

3.
J Hum Hypertens ; 30(4): 223-4, 2016 Apr.
Article in English | MEDLINE | ID: mdl-26016597

Subject(s)
Atherosclerosis , Humans
4.
Eur J Gynaecol Oncol ; 26(1): 31-5, 2005.
Article in English | MEDLINE | ID: mdl-15754996

ABSTRACT

INTRODUCTION: Tumour hypoxia has been found to be associated with tumour aggressiveness. Our primary aim was to explore the relationship between pretreatment tumour oxygenation in primary vulvar carcinoma and nodal status. Our secondary objective was to assess if there was a relationship between the clinical and biological variables. METHODS: 20 women with ISCC of the vulva were assessed with pretreatment primary tumour oxygenation with an Eppendorf pO2 probe. Patients underwent standard surgical management. Pathological assessment of the primary and nodal tissues was then performed. Primary tumour specimens were also stained for microvessel density and carbonic anhydrase IX. The relationship between smoking, preoperative Hgb, tumour CAIX expression, MVD, and Eppendorf pO2 measurements vs nodal metastasis and between these clinical and biological variables was assessed. RESULTS: Seven patients had positive lymph nodes, 13 had negative nodes. While neither current smoking status, tumour size, tumour oxygen measurements, MVD and CAIX expression correlated with metastatic nodal disease, a low preoperative Hgb correlated with pathological nodal status (p < 0.027). CONCLUSIONS: Although this analysis failed to demonstrate a strong correlation between various measures of tumour oxygenation with nodal metastasis, it may be due to the small number of patients. Only preoperative anaemia is correlated with nodal metastasis in early ISCC of the vulva.


Subject(s)
Carcinoma, Squamous Cell/metabolism , Oxygen , Vulvar Neoplasms/metabolism , Aged , Carcinoma, Squamous Cell/secondary , Female , Humans , Lymph Nodes/metabolism , Lymphatic Metastasis , Neoplasm Invasiveness , Oxygen Consumption , Predictive Value of Tests , Vulvar Neoplasms/pathology
5.
Ann Clin Biochem ; 37 ( Pt 4): 467-70, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10902862

ABSTRACT

Increased numbers of requests for serological investigation of coeliac disease, and a local trend to request both anti-gliadin antibodies (AGA) and anti-endomysium antibodies (AEA) simultaneously, resulted in cost pressures that prompted a review of our practice. Serology results from all patients (771 children, 511 adults) investigated for coeliac disease over a 3-year period were compared with small intestine histology where available. IgG AGA and IgA AGA were measured by enzyme-linked immunosorbent assay (in-house), IgA AEA by immunofluorescence (send-away contract). Overall diagnostic performance was as follows: AGA sensitivity 84%, specificity 88%, positive predictive value (PPV) 24%, negative predictive value (NPV) 99%; AEA sensitivity 88%, specificity 97%, PPV 65%, NPV 99%. Results showed AGA, with its high NPV, to be a suitable first-line test to exclude coeliac disease. The high specificity of AEA makes it a suitable confirmatory test when AGA is positive. Introduction of this step-wise approach to coeliac disease investigation resulted in cost savings of at least Pound Sterling 5000 per year without detriment to the clinical service.


Subject(s)
Celiac Disease/blood , Celiac Disease/diagnosis , Chemistry, Clinical/economics , Adolescent , Adult , Antibodies/metabolism , Chemistry, Clinical/methods , Child , Child, Preschool , Cost-Benefit Analysis , Enzyme-Linked Immunosorbent Assay , Fluorescent Antibody Technique , Gliadin/immunology , Humans , Immunoglobulin A/immunology , Immunoglobulin G/immunology , Intestine, Small/pathology , Middle Aged , Muscle Fibers, Skeletal/immunology , Predictive Value of Tests , Sensitivity and Specificity
6.
EMBO J ; 19(11): 2739-50, 2000 Jun 01.
Article in English | MEDLINE | ID: mdl-10835371

ABSTRACT

Spo11, a type II topoisomerase, is likely to be required universally for initiation of meiotic recombination. However, a dichotomy exists between budding yeast and the animals Caenorhabditis elegans and Drosophila melanogaster with respect to additional roles of Spo11 in meiosis. In Saccharomyces cerevisiae, Spo11 is required for homolog pairing, as well as axial element (AE) and synaptonemal complex (SC) formation. All of these functions are Spo11 independent in C.elegans and D.melanogaster. We examined Spo11 function in a multicellular fungus, Coprinus cinereus. The C.cinereus spo11-1 mutant shows high levels of homolog pairing and occasionally forms full-length AEs, but no SC. In C.cinereus, Spo11 is also required for maintenance of meiotic chromosome condensation and proper spindle formation. Meiotic progression in spo11-1 is aberrant; late in meiosis basidia undergo programmed cell death (PCD). To our knowledge, this is the first example of meiotic PCD outside the animal kingdom. Ionizing radiation can partially rescue spo11-1 for both AE and SC formation and viable spore production, suggesting that the double-strand break function of Spo11 is conserved and is required for these functions.


Subject(s)
Chromosomes, Fungal/physiology , Coprinus/enzymology , DNA Topoisomerases, Type II/physiology , Esterases/physiology , Fungal Proteins/physiology , Meiosis/physiology , Amino Acid Sequence , Apoptosis , Chromosomes, Fungal/radiation effects , Coprinus/cytology , Coprinus/genetics , Coprinus/radiation effects , DNA Topoisomerases, Type II/genetics , DNA, Fungal/genetics , DNA, Fungal/metabolism , DNA, Fungal/radiation effects , Endodeoxyribonucleases , Esterases/genetics , Fungal Proteins/genetics , Molecular Sequence Data , Prophase , Sequence Alignment , Sequence Deletion , Sequence Homology, Amino Acid , Species Specificity , Spindle Apparatus/physiology , Spindle Apparatus/ultrastructure , Synaptonemal Complex
7.
Apoptosis ; 5(2): 189-96, 2000 Apr.
Article in English | MEDLINE | ID: mdl-11232247

ABSTRACT

Leishmania major (Lm) infection in mice is a prototypical model for the role of immune deviation in disease resistance. Resistant strains of mice develop a Th1 response to Lm infection, distinguished by secretion of IL-12 and interferon gamma. In contrast, susceptible strains display sustained IL-4 expression characteristic of a Th2 response. However, when mechanisms of cell death are blocked, mice display a susceptible phenotype even in the presence of a strong Th1 response, suggesting that cell death, and not cytokine bias, may be an important factor in disease resistance. Here, we investigated this hypothesis by comparing lymphocyte cellularity, cell death and Fas expression in resistant CBA and susceptible BALB/c mice during the course of Lm infection. We found that delayed onset of cell death and late Fas induction correlated with massive lymphocyte accumulation and susceptibility to leishmaniasis, while early cell death and rapid Fas induction occurred in resistant mice.


Subject(s)
Apoptosis/physiology , Leishmania major , Leishmaniasis, Cutaneous/immunology , Lymphocytes/physiology , fas Receptor/metabolism , Animals , Disease Susceptibility , Female , Flow Cytometry , Humans , Immunity, Innate , In Situ Nick-End Labeling , Lymph Nodes/cytology , Lymph Nodes/pathology , Mice , Mice, Inbred BALB C , Mice, Inbred CBA , Spleen/cytology
8.
Tree Physiol ; 20(1): 1-12, 2000 Jan.
Article in English | MEDLINE | ID: mdl-12651521

ABSTRACT

We compared leaf gas exchange and water potential among the dominant tree species and major size classes of trees in an upland, pine-oak forest in northern Arizona. The study included old-growth Gambel oak (Quercus gambelii Nutt.), and sapling, pole, and old-growth ponderosa pines (Pinus ponderosa var. scopulorum Dougl. ex Laws.). Old-growth oak had higher predawn leaf water potential (Psi(leaf)) than old-growth pine, indicating greater avoidance of soil water stress by oak. Old-growth oak had higher stomatal conductance (G(w)), net photosynthetic rate (P(n)), and leaf nitrogen concentration, and lower daytime Psi(leaf) than old-growth pine. Stomatal closure started at a daytime Psi(leaf) of about -1.9 MPa for pine, whereas old-growth oak showed no obvious reduction in G(w) at Psi(leaf) values greater than -2.5 MPa. In ponderosa pine, P(n) and G(w) were highly sensitive to seasonal and diurnal variations in vapor pressure deficit (VPD), with similar sensitivity for sapling, pole, and old-growth trees. In contrast, P(n) and G(w) were less sensitive to VPD in Gambel oak than in ponderosa pine, suggesting greater tolerance of oak to atmospheric water stress. Compared with sapling pine, old-growth pine had lower morning and afternoon P(n) and G(w), predawn Psi(leaf), daytime Psi(leaf), and soil-to-leaf hydraulic conductance (K(l)), and higher foliar nitrogen concentration. Pole pine values were intermediate between sapling and old-growth pine values for morning G(w) and daytime Psi(leaf), similar to sapling pine for predawn Psi(leaf), and similar to old-growth pine for morning and afternoon P(n), afternoon G(w), K(l), and foliar nitrogen concentration. For the pines, low predawn Psi(leaf), daytime Psi(leaf), and K(l) were associated with low P(n) and G(w). Our data suggest that hydraulic limitations are important in reducing P(n) in old-growth ponderosa pine in northern Arizona, and indicate greater avoidance of soil water stress and greater tolerance of atmospheric water stress by old-growth Gambel oak than by old-growth ponderosa pine.

9.
J Virol ; 73(7): 5630-6, 1999 Jul.
Article in English | MEDLINE | ID: mdl-10364312

ABSTRACT

Coxsackievirus B3 (CVB3) infection induces myocardial inflammation and myocyte necrosis in some, but not all, strains of mice. C57BL/6 mice, which inherently lack major histocompatibility complex (MHC) class II IE antigen, develop minimal cardiac lesions despite high levels of virus in the heart. The present experiments evaluate the relative roles of class II IA and IE expression on myocarditis susceptibility in four transgenic C57BL/6 mouse strains differing in MHC class II antigen expression. Animals lacking MHC class II IE antigen (C57BL/6 [IA+ IE-] and ABo [IA- IE-]) developed minimal cardiac lesions subsequent to infection despite high concentrations of virus in the heart. In contrast, strains expressing IE (ABo Ealpha [IA- IE+] and Bl.Tg.Ealpha [IA+ IE+]) had substantial cardiac injury. Myocarditis susceptibility correlated to a Th1 (gamma interferon-positive) cell response in the spleen, while disease resistance correlated to a preferential Th2 (interleukin-4-positive) phenotype. Vgamma/Vdelta analysis indicates that distinct subpopulations of gamma delta+ T cells are activated after CVB3 infection of C57BL/6 and Bl.Tg.Ealpha mice. Depletion of gamma delta+ T cells abrogated myocarditis susceptibility in IE+ animals and resulted in a Th1-->Th2 phenotype shift. These studies indicate that the MHC class II antigen haplotype controls myocarditis susceptibility, that this control is most likely mediated through the type of gamma delta T cells activated during CVB3 infection, and finally that different subpopulations of gamma delta+ T cells may either promote or inhibit Th1 cell responses.


Subject(s)
Coxsackievirus Infections/immunology , Enterovirus B, Human , Histocompatibility Antigens Class II/immunology , Myocarditis/immunology , Receptors, Antigen, T-Cell, gamma-delta/immunology , T-Lymphocytes/immunology , Animals , Autoimmune Diseases/immunology , Autoimmune Diseases/pathology , Autoimmune Diseases/virology , Coxsackievirus Infections/pathology , Disease Models, Animal , Disease Susceptibility/immunology , Female , Histocompatibility Antigens Class II/genetics , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Myocarditis/pathology , Myocarditis/virology , Th1 Cells/immunology
10.
Immunol Cell Biol ; 76(4): 350-6, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9723776

ABSTRACT

It is demonstrated that methotrexate/cisplatin-sensitive L1210 cells express low levels of major histocompatibility complex (MHC) class II relative to the high levels expressed on methotrexate (MTX)/cisplatin-resistant L1210/DDP cells. L1210 cells express cell-surface Fas, while the L1210/DDP cells express no cell-surface Fas. Expression of costimulatory molecules B7-1/B7-2 and Fas is increased on L1210 cells, but not L1210/DDP, in the presence of methotrexate or trimetrexate (TMTX). Therefore, a component of the mechanism of action of some anti-cancer agents may be to facilitate immune recognition and T cell-directed, Fas-induced cell death. Loss of cell-surface Fas expression and failure of Fas (CD95)-dependent apoptotic death has been observed when cells develop drug resistance. The defect in apoptosis can be overcome by anti-cancer agents or experimental manipulation that induce Fas expression on the drug-resistant cells.


Subject(s)
Antigens, CD/biosynthesis , Antimetabolites, Antineoplastic/pharmacology , B7-1 Antigen/biosynthesis , Immune System/drug effects , Membrane Glycoproteins/biosynthesis , fas Receptor/biosynthesis , Animals , Apoptosis , B7-2 Antigen , Carcinogens/pharmacology , Cell Line , Dose-Response Relationship, Drug , Drug Resistance , Kinetics , Methotrexate/pharmacology , Mice , Staurosporine/pharmacology , Trimetrexate/pharmacology
12.
Ann Clin Biochem ; 32 ( Pt 6): 557-60, 1995 Nov.
Article in English | MEDLINE | ID: mdl-8579288

ABSTRACT

Urinary excretion of heparan sulphate proteoglycan (HSPG), the main anionic component of the glomerular basement membrane (GBM), was estimated in 30 adolescents and young adults with insulin dependent diabetes (IDDM), 10 with microalbuminuria and 20 sex matched, diabetic controls of similar age without evidence of microalbuminuria. A further 10 non-diabetic control subjects were also examined. Both groups of patients with diabetes had significantly elevated excretion of HSPG when compared to normal individuals. There was no difference in HSPG excretion between diabetic subjects with and without microalbuminuria.


Subject(s)
Diabetes Mellitus, Type 1/urine , Heparitin Sulfate/urine , Proteoglycans/urine , Adolescent , Adult , Albuminuria , Child , Creatinine/urine , Female , Glycated Hemoglobin/urine , Glycosaminoglycans/urine , Heparan Sulfate Proteoglycans , Humans , Male , Predictive Value of Tests
13.
Ann Clin Biochem ; 31 ( Pt 2): 147-52, 1994 Mar.
Article in English | MEDLINE | ID: mdl-8060093

ABSTRACT

The specific binding of 1,9-dimethylmethylene blue (DMB) with glycosaminoglycans (GAGs) was studied including molecular analysis of the GAG species using mass spectrometry. The dye solution was unstable under any storage conditions. Inorganic analysis showed that the purity of the dye was variable from different sources. False negative results could be obtained when using impure dye. Binding of the dye with GAG resulted in the formation of a complex with an absorption maximum at 525 nm. The absorbance of the complex was linearly correlated with GAG concentration up to 150 mg/L. The specific molar extinction coefficients of individual GAG molecules were calculated in relation to the molar absorbance of the GAG-dye complex and the carbon and nitrogen contents of the GAGs. The results indicated that binding of dye occurred at both the ionized sulphate and carboxyl groups on the GAG molecules. Improvements of the DMB-binding method for the measurement of GAGs are suggested.


Subject(s)
Glycosaminoglycans/metabolism , Methylene Blue/analogs & derivatives , Drug Storage , Glycosaminoglycans/chemistry , Mass Spectrometry , Methylene Blue/metabolism , Spectrophotometry, Ultraviolet
14.
Gastroenterology ; 101(6): 1488-96, 1991 Dec.
Article in English | MEDLINE | ID: mdl-1955115

ABSTRACT

The effects of an antibacterially effective IV dose of erythromycin on gastrointestinal motor activity were investigated in eight normal healthy human volunteers in the fasted state and the fed state. Motor activity was recorded by a multilumen manometric tube. Data were analyzed visually and by a computer method. Blood samples were obtained for erythromycin and motilin assays. In the gastric antrum, erythromycin significantly increased the total duration, amplitude, and area under contractions from 0 to 60 minutes and frequency of contractions from 0 to 30 minutes from the start of its infusion in the fasted state. A similar response in the fed state occurred mostly from 0 to 30 minutes after the start of erythromycin infusion. By contrast, erythromycin inhibited the frequency and decreased the duration of small intestinal contractions in the fed state but had no effect in the fasted state. The gastric motor response was related to the plasma concentration of erythromycin, but not to plasma motilin. Erythromycin significantly shortened the duration of migrating motor complex disruption by a meal. Erythromycin also induced symptoms of upper abdominal pain, bloating, and nausea. Abdominal pain was related to strong antral contractions in both fasted and fed states; bloating occurred only in the fed state. Nausea occurred in both fasted and fed states, but it was not related to any specific pattern of motor activity. It is concluded that the strong antral contractions induced by erythromycin may accelerate the rate of gastric emptying, but they may also be responsible for causing the sensations of upper abdominal pain and bloating. The motor response to erythromycin is less during the fed than during the fasted state. The strong antral contractions induced by erythromycin are not mediated by the release of motilin.


Subject(s)
Erythromycin/pharmacology , Gastrointestinal Motility/drug effects , Abdominal Pain/etiology , Adult , Eating/physiology , Erythromycin/adverse effects , Erythromycin/blood , Fasting/physiology , Gastric Emptying/drug effects , Humans , Intestine, Small/drug effects , Male , Motilin/blood , Peristalsis/drug effects , Pyloric Antrum/drug effects
15.
J Stud Alcohol ; 51(5): 389-95, 1990 Sep.
Article in English | MEDLINE | ID: mdl-2232790

ABSTRACT

In a carefully executed study with a high response rate, a random sample of 10% of the undergraduate student body at a rural New England university was surveyed as to the subjects' use of alcohol in 1987. Over 87% of the surveyed students returned questionnaires. The results were compared to similar studies conducted on the campus in 1977 and 1983. "Daily or almost daily" use of alcohol was registered by 4.7% of the respondents, which represents a continuing decrease in daily consumption from earlier studies. One-fourth of the sample indicated drinking only one drink or fewer per week, contrary to the common perception on the campus. Nevertheless, 25.5% recorded a hangover, 7.5% recorded vomiting from drinking too much and 4.4% recorded a blackout, all "in the last week." Compared to the U.S. population, alcohol consumption appears to be more evenly distributed in the college sample but, still, most of the drinking is done by one-fifth of both groups.


Subject(s)
Alcohol Drinking/trends , Alcoholism/epidemiology , Rural Population/statistics & numerical data , Students/statistics & numerical data , Absenteeism , Accidents, Traffic/statistics & numerical data , Adolescent , Adult , Age Factors , Alcoholic Intoxication/epidemiology , Cross-Sectional Studies , Female , Humans , Incidence , Male , New England/epidemiology , Sex Factors
16.
Int J Addict ; 25(9): 1025-36, 1990 Sep.
Article in English | MEDLINE | ID: mdl-2090632

ABSTRACT

A random sample of 10% of the undergraduate student body at a rural New England university were surveyed as to their use of drugs in 1987. Over 87% of the surveyed students returned questionnaires. Results indicated that alcohol is clearly the "drug of choice" on the campus, and the second most used drug is marijuana. The 1987 survey findings were also compared to similar studies conducted on the campus in 1977 and 1983. Over the decade there has been a decrease in daily, weekly, and monthly use of marijuana. Cocaine use was greatest in the 1983 survey, but the 1987 figures were still somewhat higher than those of 1977. Hallucinogen use has remained low across all three observation points. Students indicating they had substance-dependent parents showed more use of cocaine, "ecstasy," and sedative-hypnotic drugs than their fellow students.


Subject(s)
Students/statistics & numerical data , Substance-Related Disorders/epidemiology , Adolescent , Adult , Alcohol Drinking/epidemiology , Alcoholism/epidemiology , Cross-Sectional Studies , Female , Humans , Illicit Drugs , Incidence , Male , New England/epidemiology
17.
Bull World Health Organ ; 62(1): 115-20, 1984.
Article in English | MEDLINE | ID: mdl-6609016

ABSTRACT

Screening methods for anaemia were selected for testing on the grounds of cheapness, simplicity, sturdiness, accuracy and independence of mains electricity or batteries. The methods evaluated were the copper sulfate method, the Dare haemoglobinometer, the Lovibond comparator, the A. O. Spencer haemoglobinometer, and the Tallqvist method. A new device, the Carib haemoglobin comparator, was developed. The Dare and Lovibond instruments were found to be inaccurate in the laboratory. The other instruments were tested by primary health care workers in clinics in Jamaica. The Carib haemoglobin comparator and the copper sulfate method were found to be accurate, easy to use, and cheap. Both methods are considered to be useful for screening for anaemia at primary health care level.


Subject(s)
Anemia/diagnosis , Copper , Copper Sulfate , Hemoglobinometry/instrumentation , Humans , Indicators and Reagents
19.
Bull. W.H.O. (Print) ; 62(1): 115-120, 1984.
Article in English | WHO IRIS | ID: who-265018

Subject(s)
Research
20.
Ann Ophthalmol ; 15(2): 141-9, 1983 Feb.
Article in English | MEDLINE | ID: mdl-6301342

ABSTRACT

The effects of topical 0.5% timolol maleate and 1% or 2% levo-epinephrine hydrochloride on aqueous humor cyclic-AMP and intraocular pressure were assessed in 97 normotensive New Zealand white rabbits in vivo. The study was conducted using three experimental protocols: (A) timolol and epinephrine individually, (B) timolol and epinephrine in coadministration, and (C) timolol and epinephrine in crossover, applied either in a single dose, twice a day for two days, and/or twice a day for six days. These studies demonstrated that timolol has complex biochemical actions, one of which is beta-adrenergic antagonism. By itself, timolol had no effect on cyclic-AMP levels. However, when used in both single-dose coadministration and in pretreatment in six-day crossover with epinephrine, it significantly diminished the cyclic-AMP elevation produced by a single dose of epinephrine. In the six-day crossover protocol, pretreatment with timolol also significantly reduced the ocular hypotensive effect of a single dose of epinephrine, thereby correlating biochemical cause with clinical effect. Yet, timolol alone had no ocular hypotensive effect. Therefore, timolol's biochemical actions in this animal model cannot explain its marked clinical efficacy in man, which appears to depend on more complex pharmacologic actions.


Subject(s)
Epinephrine/administration & dosage , Eye/metabolism , Propanolamines/administration & dosage , Timolol/administration & dosage , Administration, Topical , Animals , Aqueous Humor/metabolism , Cyclic AMP/metabolism , Drug Combinations , Epinephrine/pharmacology , Rabbits , Timolol/pharmacology
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