Determinants of Early Childhood Caries and their interactions: A Structural Equation Modelling approach.

OBJECTIVE: Early Childhood Caries (ECC) has been common among preschoolers in Sri Lanka over decades. A broad spectrum of determinants that act upon different levels is responsible for its development. Therefore, the relationships among these determinants should be studied extensively to control ECC. DESIGN: Descriptive cross-sectional study with multistage cluster sampling. SETTING: Registered preschools in Gampaha District. PARTICIPANTS: A total of 1038 three to four-year-olds and their mothers. MAIN OUTCOME MEASURES: Direct, indirect, and total effects of the determinants of ECC in structural equation models. RESULTS: Sweet consumption had direct effects from permissive parenting (ß=0.26, p=0.00) and the sweet consumption behaviour of the family (ß=0.17, p=0.01). Oral hygiene behaviours had direct effects from permissive parenting (ß=-0.46, p=0.00) and maternal oral health related self-efficacy (ß=0.23, p=0.00). The dental attendance pattern had total effects from knowledge (ß=0.18, p=0.00) and permissive parenting (ß=-0.16, p=0.00). CONCLUSIONS: Parenting style, family sweet consumption behaviour and maternal oral health related self-efficacy were the most influential second-line determinants that affected oral health behaviours: sweet consumption, oral hygiene, and dental attendance pattern for the development of ECC.

Metabolic Changes in Seed Embryos of Hypoxia-Tolerant Rice and Hypoxia-Sensitive Barley at the Onset of Germination.

Rice (Oryza sativa L.) and barley (Hordeum vulgare L.) are the cereal species differing in tolerance to oxygen deficiency. To understand metabolic differences determining the sensitivity to low oxygen, we germinated rice and barley seeds and studied changes in the levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS), activities of the enzymes involved in their scavenging, and measured cell damage parameters. The results show that alcohol dehydrogenase activity was higher in rice than in barley embryos providing efficient anaerobic fermentation. Nitric oxide (NO) levels were also higher in rice embryos indicating higher NO turnover. Both fermentation and NO turnover can explain higher ATP/ADP ratio values in rice embryos as compared to barley. Rice embryos were characterized by higher activity of S-nitrosoglutathione reductase than in barley and a higher level of free thiols in proteins. The activities of antioxidant enzymes (superoxide dismutase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase) in imbibed embryos were higher in rice than in barley, which corresponded to the reduced levels of ROS, malonic dialdehyde and electrolyte leakage. The observed differences in metabolic changes in embryos of the two cereal species differing in tolerance to hypoxia can partly explain the adaptation of rice to low oxygen environments.

Heavy metal accumulation in two synanthropic avian species in Sri Lanka.

We assessed the levels of Pb, Cd, and Mn in contour feathers of the feral pigeon (Columba livia) and house crow (Corvus splendens) obtained from five urban/suburban locations across Sri Lanka, using the AAS following wet digestion. Our key objectives were to compare accumulation levels in the two avian species with different foraging habits and living in common locations, and to establish baseline information on the presence of these metals in multiple locations in Sri Lanka with varying levels of urbanization. Owing to reservations that have been expressed by previous workers regarding the use of feathers for assessing heavy metal pollution, we first tested the efficacy of contour feathers by using our data for comparing the coefficients of variation in metal levels within and between locations. This showed that in over 95% of the cases, variations within locations were lower than between locations, indicating that freshly shed contour feathers that were used in the present study were reliable indicators of the status of bioaccumulation of the heavy metals in the environment. In interspecific comparisons, other than in the two suburban locations, Pb was present at much higher levels in the house crow than in the feral pigeon, whereas accumulation patterns with respect to Cd and Mn were inconsistent, suggesting that granivores may not, in all situations, accumulate lower levels than scavengers in the same environment. Owing to such interspecific variations in the patterns of accumulation of different heavy metals, the selection of a single species for assessing levels of pollution from heavy metals may not be prudent. Pb and Cd levels in both species were strongly and positively associated with human population density. The levels of Pb and Cd were highest in Colombo (commercial capital). In Colombo and Kalutara, the recorded levels in the house crow exceeded the thresholds that have the potential to inflict adverse impacts on avian species.

Inter-population variation in thermal sensitivity of the tropical toad Duttaphrynus melanostictus, across a small spatial scale in Sri Lanka.

Inter-population disparities in a species have been shown to occur as an adaptation to different thermal regimes in the environment. We investigated the thermal sensitivities of the tropical toad Duttaphrynus melanostictus (Asia Common Toad) from two populations at different altitudes: Nuwara-Eliya - 1870 m, and Polonnaruwa - 25 m, above mean sea level. The two locations were separated by what may be considered a short direct distance - 110 km. Thermal sensitivity trials were conducted at six temperatures between 12 and 39 °C. Assessments were made using the performance indicators jump distance, jump force, contact time on the test plate following stimulus to jump, and righting time after being overturned. Optimum performance is taken to be the greatest jump distance and jump force, the least contact time on the test plate, and the least righting time. The populations at the two altitudes had markedly different thermal sensitivities - toads in the cool area (Nuwara-Eliya) performed at an optimal level under low temperatures, whereas the toads in the warm area (Polonnaruwa) performed optimally under high temperatures. The finding that the thermal optima (i.e., the temperatures at which the optimal performance for the four performance indicators was recorded) of the toads in Polonnaruwa were below the mean maximum ambient temperature at this location suggests that these toads would be more susceptible to global warming than those in Nuwara-Eliya whose thermal optima were above the mean maximum ambient temperature in that location. This was consistent with the narrower thermal safety margin (i.e., difference between the mean optimum temperature and mean ambient temperature) of toads in Polonnaruwa, compared to those in Nuwara-Eliya. Importantly, these findings demonstrate that, although thermal sensitivity is considered a conservative trait, differentiation does occur even over a small spatial scale presumably because it offers an adaptive advantage to the population concerned.

The PEARL score predicts 90-day readmission or death after hospitalisation for acute exacerbation of COPD.

BACKGROUND: One in three patients hospitalised due to acute exacerbation of COPD (AECOPD) is readmitted within 90 days. No tool has been developed specifically in this population to predict readmission or death. Clinicians are unable to identify patients at particular risk, yet resources to prevent readmission are allocated based on clinical judgement. METHODS: In participating hospitals, consecutive admissions of patients with AECOPD were identified by screening wards and reviewing coding records. A tool to predict 90-day readmission or death without readmission was developed in two hospitals (the derivation cohort) and validated in: (a) the same hospitals at a later timeframe (internal validation cohort) and (b) four further UK hospitals (external validation cohort). Performance was compared with ADO, BODEX, CODEX, DOSE and LACE scores. RESULTS: Of 2417 patients, 936 were readmitted or died within 90 days of discharge. The five independent variables in the final model were: Previous admissions, eMRCD score, Age, Right-sided heart failure and Left-sided heart failure (PEARL). The PEARL score was consistently discriminative and accurate with a c-statistic of 0.73, 0.68 and 0.70 in the derivation, internal validation and external validation cohorts. Higher PEARL scores were associated with a shorter time to readmission. CONCLUSIONS: The PEARL score is a simple tool that can effectively stratify patients' risk of 90-day readmission or death, which could help guide readmission avoidance strategies within the clinical and research setting. It is superior to other scores that have been used in this population. TRIAL REGISTRATION NUMBER: UKCRN ID 14214.

Validation of the DECAF score to predict hospital mortality in acute exacerbations of COPD.

BACKGROUND: Hospitalisation due to acute exacerbations of COPD (AECOPD) is common, and subsequent mortality high. The DECAF score was derived for accurate prediction of mortality and risk stratification to inform patient care. We aimed to validate the DECAF score, internally and externally, and to compare its performance to other predictive tools. METHODS: The study took place in the two hospitals within the derivation study (internal validation) and in four additional hospitals (external validation) between January 2012 and May 2014. Consecutive admissions were identified by screening admissions and searching coding records. Admission clinical data, including DECAF indices, and mortality were recorded. The prognostic value of DECAF and other scores were assessed by the area under the receiver operator characteristic (AUROC) curve. RESULTS: In the internal and external validation cohorts, 880 and 845 patients were recruited. Mean age was 73.1 (SD 10.3) years, 54.3% were female, and mean (SD) FEV1 45.5 (18.3) per cent predicted. Overall mortality was 7.7%. The DECAF AUROC curve for inhospital mortality was 0.83 (95% CI 0.78 to 0.87) in the internal cohort and 0.82 (95% CI 0.77 to 0.87) in the external cohort, and was superior to other prognostic scores for inhospital or 30-day mortality. CONCLUSIONS: DECAF is a robust predictor of mortality, using indices routinely available on admission. Its generalisability is supported by consistent strong performance; it can identify low-risk patients (DECAF 0-1) potentially suitable for Hospital at Home or early supported discharge services, and high-risk patients (DECAF 3-6) for escalation planning or appropriate early palliation. TRIAL REGISTRATION NUMBER: UKCRN ID 14214.

Histological Alterations in the Body Wall of the Tropical Earthworm Eudrilus eugeniae Exposed to Hexavalent Chromium.

The tropical earthworm Eudrilus eugeniae was chronically exposed to hexavalent chromium (Cr) in its substrate over a concentration range from 0.24 to 893 mg kg(-1). Histological alterations in the body wall epithelium included cell fusion, reduction in thickness of the epithelial layer, a marked increase in pyknotic nuclei and epithelial sloughing. Similar changes were noted in the circular and longitudinal muscles with damage being indicated by the prominent inter-muscular cell spaces and disintegration. Many of these noted alterations intensified with increasing levels of exposure. It is significant that some of the changes recorded here were evident even at the lowest concentration of 0.24 mg kg(-1), an environmentally relevant concentration. Hence, the observed trends could be taken as an early warning to the imminent threats of heavy metal pollution to epigeic earthworm species.

Cadmium-induced toxicity on larvae of the common Asian toad Duttaphrynus melanostictus (Schneider 1799): evidence from empirical trials.

This paper investigates the toxicity of cadmium (Cd) on young stages of the common Asian toad Duttaphrynus melanostictus (Schneider 1799). Signs of acute toxicity were evident in tadpoles repeatedly exposed to five concentrations ranging from 0.002 to 2 mg L(-1)of Cd which included environmentally relevant levels. Mortality at concentrations of 0.02 mg L(-1) and above was enhanced from 2 % at 0.02 mg L(-1) to 100 % at 1 mg L(-1), in a dose-dependent manner. Significant growth impairment was evident at 0.20 mg L(-1) with the larvae being markedly smaller. Delayed metamorphosis and retarded swimming were also observed. Therefore levels of Cd recorded in some freshwater bodies in Sri Lanka (e.g. 0.2 mg L(-1)) may be detrimental to the young stages of D. melanostictus.

Cross-matched blood in colorectal surgery: a clinical waste?

AIM: This study was carried out to determine the rate of perioperative blood transfusion and to create an evidence-based approach to requesting blood for elective colorectal surgery. METHOD: A comparative cohort study was carried out of 164 patients (107 men, 57 women, median age 68 years) who underwent major colorectal surgery. Details obtained included demographic and operative information, the number of units of blood cross-matched, units used, the reasons for transfusion and patient suitability for electronic issue (EI). The cross-match to transfusion ratio (C:T ratio) was calculated for each procedure and for the whole group of colorectal procedures. RESULTS: Some 162 units of blood were cross-matched for 76 (46%) patients, with the remaining 88 (54%) being grouped with serum saved. Twenty-one (13%) were transfused with a total of 48 units of blood. The C:T ratio for all procedures was 3.4/1. The commonest indication for transfusion was anaemia. One patient required an emergency transfusion. The majority (78%) of patients were suitable for EI. There were no significant differences between the transfused and nontransfused groups with regard to age, diagnosis (malignant vs benign) and laparoscopic or open colorectal procedure. CONCLUSION: Only a small proportion of patients undergoing elective major colorectal surgery require perioperative blood transfusions, most of which are nonurgent. Blood should not be routinely cross-matched in patients who are suitable for EI.

Assessing PaCO2 in acute respiratory disease: accuracy of a transcutaneous carbon dioxide device.

BACKGROUND: Pulse oximetry non-invasively assesses the arterial oxygen saturation of patients with acute respiratory disease; however, measurement of the arterial partial pressure of carbon dioxide (PaCO(2)) requires an arterial blood gas. The transcutaneous partial pressure of carbon dioxide (PtCO(2) ) has been used in other settings with variable accuracy. We investigated the accuracy of a PtCO(2) device in the assessment of PaCO(2) in patients with asthma and suspected pneumonia attending the emergency department. METHODS: Patients with severe asthma (FEV(1) < 50% predicted) or suspected pneumonia (fever, cough and respiratory rate >18/min) were enrolled. Subjects were excluded if they had a history of chronic obstructive pulmonary disease or other conditions associated with respiratory failure. Arterial blood gases were taken at the discretion of the investigator according to clinical need, and paired with a simultaneous reading from the PtCO(2) probe. RESULTS: Twenty-five patients were studied with one set of data excluded because of poor PtCO(2) signal quality. The remaining 24 paired samples comprised 12 asthma and 12 pneumonia patients. The range of PaCO(2) was 19-64 mmHg with a median of 36.5 mmHg. Bland-Altman analysis showed a mean (SD) PaCO(2) - PtCO(2) difference of -0.13 (1.9) mmHg with limits of agreement of plus or minus 3.8 mmHg (-3.9 to +3.7). CONCLUSION: A PtCO(2) device was accurate in the assessment of PaCO(2) in patients with acute severe asthma and suspected pneumonia when compared with an arterial blood gas. These bedside monitors have the potential to improve patient care by non-invasively monitoring patients with acute respiratory disease at risk of hypercapnia.

Pre-hospital oxygen therapy in acute exacerbations of chronic obstructive pulmonary disease.

BACKGROUND: High concentration oxygen is commonly administered during acute exacerbations of chronic obstructive pulmonary disease (AECOPD). The aim of this study was to determine the association between oxygen, severity markers and poor outcomes in AECOPD. METHODS: In an audit of patients with AECOPD arriving by ambulance to the Emergency Department of Wellington Hospital, details of oxygen administration, clinical outcomes and severity markers were documented. The main outcome measure was a composite of death, assisted ventilation, or respiratory failure. Associations between oxygen therapy, severity markers and poor clinical outcomes were assessed by logistic regression. RESULTS: Of 250 patients 77 (31%) died, required assisted ventilation or were in respiratory failure. Increased oxygen flow was associated with increasing risk of death, assisted ventilation or respiratory failure with an odds ratio (OR) of 1.2 (95% CI 1.0-1.4) per 1 L/min oxygen flow. Increasing PaO(2) was associated with a greater risk of a poor outcome with an OR of 1.1 (95% CI 1.0-1.3) per 10 mmHg higher PaO(2). Home oxygen (OR 2.8, 95% CI 1.5-5.1), previous respiratory failure (OR 2.6, 95% CI 1.5-4.6), previous ventilation (OR 3.2, 95% CI 1.7-5.9) and home nebulizer use (OR 2.4, 95% CI 1.4-4.3) were associated with an increased risk of a poor outcome. CONCLUSION: In AECOPD high flow oxygen in the ambulance is associated with poor clinical outcomes. A number of easily identified markers of chronic disease severity indicate an increased risk of a poor clinical outcome.

Chlorpyrifos-induced toxicity in Duttaphrynus melanostictus (Schneider 1799) larvae.

This study investigates the effects of continuous exposure to a widely used organophosphate pesticide, chlorpyrifos, on survival, growth, development, and activity of larvae of the Asian common toad, Duttaphrynus melanostictus Schneider 1799. Larvae were continuously exposed to six different concentrations (1-1,500 µg l(-1)) of commercial-grade chlorpyrifos for 14 days and monitored for 1 additional week. Chlorpyrifos at ≥1,000 µg l(-1) caused significantly high and dose-dependent mortality, and the weekly LC50(7 day-21 day) values ranged from 3,003 to 462 µg l(-1). Larvae surviving exposure to ≥500 µg l(-1) chlorpyrifos showed significant growth impairment, delays in metamorphosis, and decreased swimming activity. Tail abnormalities were the most common morphologic deformity at concentrations of 1,000 and 1,500 µg l(-1) chlorpyrifos. The findings of the present study highlight the need to recognize the potential risk that agrochemicals pose to amphibians inhabiting agricultural landscapes in Sri Lanka and other Asian countries.

Meta-analysis of the risk of mortality with salmeterol and the effect of concomitant inhaled corticosteroid therapy.

BACKGROUND: There is concern that long-acting beta agonist (LABA) drugs may increase the risk of asthma mortality. METHODS: A meta-analysis was conducted of asthma deaths in randomised controlled clinical trials from the GlaxoSmithKline database that compared salmeterol with a non-LABA comparator treatment in asthma. The Peto one-step method was used to determine the risk overall (all studies) and in derived datasets based on inhaled corticosteroid (ICS) use. RESULTS: There were 35 asthma deaths in 215 studies with 106,575 subjects. Two studies (SMART and SNS) contributed 30/35 (86%) asthma deaths, the overall findings largely reflecting the characteristics of these studies. The odds ratio for risk of asthma mortality with salmeterol was 2.7 (95% CI 1.4 to 5.3). In 54 placebo controlled studies the risk of death from asthma in patients not prescribed ICS was 7.3 (95% CI 1.8 to 29.4). In 127 studies in which patients were prescribed ICS, the risk of asthma death was 2.1 (95% CI 0.6 to 7.9). In 63 studies in which patients were randomised to receive the combination salmeterol/fluticasone propionate inhaler or ICS, there were no asthma deaths among 22,600 patients. CONCLUSIONS: Salmeterol monotherapy in asthma increases the risk of asthma mortality and this risk is reduced with concomitant ICS therapy. There is no evidence that combination salmeterol/fluticasone propionate therapy is associated with an increased risk of asthma mortality, although this interpretation is limited by the low statistical power of available studies.

Risk of mortality associated with formoterol: a systematic review and meta-analysis.

There is concern long-acting beta-agonist (LABA) drugs may increase the risk of asthma mortality. We undertook a systematic review which included the AstraZeneca Formoterol Clinical Trial Safety Database and Novartis Food and Drug Administration Formoterol Briefing Document. Randomised controlled clinical trials of duration > or = 4 weeks that compared formoterol with a non-LABA comparator treatment in asthma were included in a meta-analysis of the risk of all-cause mortality and asthma death. Simple contingency tables, Peto's one-step method and a Bayesian analysis were used. There were 42 deaths (nine from asthma) recorded in 62 studies with 49,327 subjects. The simple contingency table odds ratio for risk of all-cause mortality with formoterol was 1.1 (95% CI 0.6-2.2) and for asthma death was 2.7 (95% CI 0.5-26.7). Analyses by the other methods using both "as randomised" and "as exposed" classifications of treatment gave similar risk estimates with wide confidence and credible intervals. We conclude that there was insufficient power to determine whether formoterol increases the risk of mortality. However, the point estimates of a 2.0- to 3.2-fold increased risk of asthma death are not reassuring and add weight to evidence that LABA use in certain circumstances may increase the risk of asthma mortality.

Survival mechanisms and culturability of Campylobacter jejuni under stress conditions.

Culture-based isolation and enumeration of bacterial human pathogens from environmental and human food samples has significant limitations.Many pathogens enter a viable but non-culturable(VBNC) state in response to stress, and cannot be detected via culturing methods. Favourable growth conditions with a source of energy and an ideal stoichiometric ratio of carbon to inorganic elements can reverse this VBNC state. This review will focus on the bacterium Campylobacter jejuni which is a leading cause of food borne illness in the developed world. C. jejuni can enter a VBNC state in response to extremes in: pH, moisture content, temperature,nutrient content and salinity. Once in a VBNC state,the organism must maintain an energy balance from substrate oxidation through respiration to grow,divide and remain viable. The goal of this review isa greater understanding of how abiotic stress and thermodynamics influence the viability of C. jejuni.

Routine use of oxygen in the treatment of myocardial infarction: systematic review.

CONTEXT: International guidelines recommend the routine use of oxygen therapy in the treatment of myocardial infarction (MI). OBJECTIVE: To undertake a systematic review and meta-analysis of randomised placebo-controlled trials of oxygen therapy in MI. DATA SOURCES: Medline, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, EMBASE and CINHAL. STUDY SELECTION: Randomised placebo-controlled trials of oxygen therapy in MI. DATA EXTRACTION: The primary clinical outcome was mortality. RESULTS: Two of 51 potential studies met the inclusion criteria. The one study with substantive clinical outcome data reported that in uncomplicated MI, high-flow oxygen was associated with a non-significant increased risk of death (risk ratio 2.9, 95% CI 0.8 to 10.3, p = 0.08) and a greater serum aspartate aminotransferase level (difference 19.2 IU/ml, 95% CI 0 to 38.4, p = 0.05) than room air. CONCLUSION: The limited evidence that does exist suggests that the routine use of high-flow oxygen in uncomplicated MI may result in a greater infarct size and possibly increase the risk of mortality.

The risk of asthma mortality with inhaled long acting beta-agonists.

This article reviews the available evidence as to whether inhaled long acting beta-agonists (LABA) increase the risk of asthma mortality and considers the implications for the use of this treatment in the management of asthma. Randomised controlled trials suggest that LABAs prescribed as monotherapy may increase the risk of asthma death in certain circumstances, such as the unsupervised "off-label" use without concomitant inhaled corticosteroid (ICS) treatment in patients with unstable asthma. However, there is also evidence that the use of LABAs in conjunction with ICS treatment in adult asthma as recommended in current guidelines is not associated with an increased risk of asthma mortality. The only way in which a prescriber can ensure that a patient with asthma takes LABA treatment in conjunction with ICS is through a combination ICS/LABA product, an approach which may have additional therapeutic advantages. We propose that in the management of asthma, a case can now be made to limit the availability of LABAs to combination LABA/ICS therapy.

Dose-response relationship for risk of non-vertebral fracture with inhaled corticosteroids.

OBJECTIVE: To determine the strength of association between the dose of inhaled corticosteroids (ICS) and risk of non-vertebral fracture in adults. METHODS: A systematic review and meta-analysis of case-control studies of non-vertebral fractures in adults, in which at least two doses of ICS were reported as the dose of beclomethasone dipropionate (BDP) or equivalent. RESULTS: Five case-control studies were identified, with a total of 43 783 cases and 259 936 controls. There was an association between the risk of non-vertebral fracture and increasing dose of BDP. The random-effects odds ratio of relative risk for a non-vertebral fracture was 1.12 (95% confidence interval 1.00-1.26) per 1000 microg increase in the daily dose of BDP or equivalent. CONCLUSION: In older adults, the relative risk of non-vertebral fractures increases by about 12% for each 1000 microg/day increase in the dose of BDP or equivalent. The magnitude of this risk was considerably less than other common risk factors for fracture in the older adult.

Prolonged seated immobility at work is a common risk factor for venous thromboembolism leading to hospital admission.

The role of seated immobility at work in the pathogenesis of venous thromboembolism (VTE) is uncertain. In this case series, 61 patients aged <65 years with a recent admission for deep venous thrombosis and/or pulmonary embolism completed an interviewer-administered questionnaire to obtain information regarding risk factors. Prolonged seated immobility at work in the 4 weeks before the VTE event was defined as being seated at least 8 h in a 24-h period and at least 3 h at a time without getting up, at least 10 h in a 24-h period and at least 2 h at a time without getting up or at least 12 h in a 24-h period and at least 1 h at a time without getting up. The most commonly identified risk factors were family history of VTE (21 of 61, 34%), seated immobility at work (21 of 61, 34%) and a thrombophilic state (19 of 61, 31%). We conclude that prolonged seated immobility at work may represent a common and important risk factor for VTE.

Imaging photopolarimeter on pioneer saturn.

An imaging photopolarimeter aboard Pioneer 11, including a 2.5-centimeter telescope, was used for 2 weeks continuously in August and September 1979 for imaging, photometry, and polarimetry observations of Saturn, its rings, and Titan. A new ring of optical depth < 2 x 10(-3) was discovered at 2.33 Saturn radii and is provisionally named the F ring; it is separated from the A ring by the provisionally named Pioneer division. A division between the B and C rings, a gap near the center of the Cassini division, and detail in the A, B, and C rings have been seen; the nomenclature of divisions and gaps is redefined. The width of the Encke gap is 876 +/- 35 kilometers. The intensity profile and colors are given for the light transmitted by the rings. A mean particle size less, similar 15 meters is indicated; this estimate is model-dependent. The D ring was not seen in any viewing geometry and its existence is doubtful. A satellite, 1979 S 1, was found at 2.53 +/- 0.01 Saturn radii; the same object was observed approximately 16 hours later by other experiments on Pioneer 11. The equatorial radius of Saturn is 60,000 +/- 500 kilometers, and the ratio of the polar to the equatorial radius is 0.912 +/- 0.006. A sample of polarimetric data is compared with models of the vertical structure of Saturn's atmosphere. The variation of the polarization from the center of the disk to the limb in blue light at 88 degrees phase indicates that the density of cloud particles decreases as a function of altitude with a scale height about one-fourth that of the gas. The pressure level at which an optical depth of 1 is reached in the clouds depends on the single-scattering polarizing properties of the clouds; a value similar to that found for the Jovian clouds yields an optical depth of 1 at about 750 millibars.