Disease outbreak response: why epidemiology plays a central role.

The need to control transboundary animal disease outbreaks is widely recognised, as is the need for evidence-based decisions regarding which control measures to implement. Key data and information are required to inform this evidence base. To ensure effective communication of the evidence, a rapid process of collation, interpretation and translation is required. This paper describes how epidemiology can provide the framework through which relevant specialists can be engaged to this end, and highlights the central role of epidemiologists, with their unique combination of skills, in this process. It provides an example of an evidence team led by epidemiologists, namely the United Kingdom National Emergency Epidemiology Group, which was established to address this need. It then goes on to consider the different strands of epidemiology, the need for a wide multidisciplinary approach, and the importance of training and preparedness activities to facilitate rapid response.

La nécessité de contrôler les foyers de maladies animales transfrontalières est largement reconnue, tout comme celle de fonder la prise de décisions sur des données probantes pour la mise en oeuvre des mesures de contrôle. Afin de documenter cette base d'éléments probants, il est nécessaire d'obtenir un certain nombre de données et d'informations clés. Un processus rapide de collecte, d'interprétation et de traduction des données doit être mis en place afin de communiquer ces éléments probants de manière efficace. Les auteurs décrivent le cadre que l'épidémiologie peut apporter aux chercheurs pour s'engager sur cette voie ; ils soulignent le rôle central des épidémiologistes dans ce processus, grâce au faisceau unique de compétences dont ils disposent. Ils donnent l'exemple d'une équipe animée par des épidémiologistes travaillant sur les données probantes qui a été mise en place spécifiquement pour répondre à ce besoin : le Groupe national d'épidémiologie d'urgence du Royaume-Uni (National Emergency Epidemiology Group). Les auteurs concluent en menant une réflexion sur les différentes branches de l'épidémiologie, le besoin d'une approche pluridisciplinaire large et l'importance des activités de formation et de préparation pour une réponse rapide.

Hay coincidencia general en que hoy resulta imperativo combatir los brotes transfronterizos de enfermedades animales, al igual que es necesario contar con un sólido fundamento de datos factuales para tomar decisiones sobre las medidas de lucha que conviene implantar. Para generar esta base empírica hay que disponer de un conjunto esencial de datos e información y para comunicarla eficazmente se requiere un rápido proceso de recogida, interpretación y traducción. Los autores explican cómo puede la epidemiología constituir el marco de referencia desde el que trabajen para tal fin los distintos especialistas y destacan la función central que cumplen en este proceso los epidemiólogos, gracias a la singular combinación de competencias que presentan. A modo de ejemplo, describen un equipo dedicado al estudio de datos factuales que fue establecido, bajo la dirección de epidemiólogos, justamente para responder a esta necesidad: el Grupo nacional de respuesta epidemiológica a situaciones de emergencia del Reino Unido (National Emergency Epidemiology Group). Por último, tras detenerse en las distintas vertientes de la epidemiología, inciden en la necesidad de abordar la cuestión desde un planteamiento ampliamente pluridisciplinar y en la importancia que revisten las actividades de formación y preparación para facilitar una respuesta rápida.

Danish VISA-A questionnaire with validation and reliability testing for Danish-speaking Achilles tendinopathy patients.

The VISA-A questionnaire has proven to be a valid and reliable tool for assessing severity of Achilles tendinopathy (AT). The aim was to translate and cross-culturally adapt the VISA-A questionnaire for a Danish-speaking AT population, and subsequently perform validity and reliability tests. Translation and following cross-cultural adaptation was performed as translation, synthesis, reverse translation, expert review, and pretesting. The final Danish version (VISA-A-DK) was tested for reliability on healthy controls (n = 75) and patients (n = 36). Tests for internal consistency, validity, and structure were performed on 71 patients. VISA-A-DK showed good reliability for patients (r = 0.80 ICC = 0.79) and healthy individuals (r = 0.98 ICC = 0.97). Internal consistency was 0.73 (Cronbach's alpha). The mean VISA-A-DK score in AT patients was 51 [47-55]. This was significantly lower than healthy controls with a score of 93 (90-95). Criterion validity was considered good when comparing the scores of the Danish version with the original version in both healthy individuals and patients. VISA-A-DK is a valid and reliable instrument and has shown compatible to the original version in assessment of AT patients. VISA-A-DK is a useful tool in the assessment of AT, both in research and in a clinical setting.

Uptake of hepatitis C treatment among people who inject drugs attending Needle and Syringe Programs in Australia, 1999-2011.

The majority of new and existing cases of hepatitis C virus (HCV) infection occur among people who inject drugs (PWID). Despite safe and efficacious HCV antiviral therapy, uptake remains low in this population. This study examined trends in HCV treatment uptake among a large national sample of PWID attending Australian Needle and Syringe Programs between 1999 and 2011. Annual cross-sectional sero-surveys conducted among PWID since 1995 involve completion of a self-administered questionnaire and provision of a dried blood spot for HCV antibody testing. Multivariate logistic regression identified variables independently associated with HCV treatment uptake among 9478 participants with both self-reported and serologically confirmed prior HCV infection. Between 1999 and 2011, the proportion currently receiving treatment increased from 1.1% to 2.1% (P < 0.001), while the proportion having ever received treatment increased from 3.4% to 8.6% (P < 0.001). Men were significantly more likely than women to have undertaken HCV treatment (P = 0.002). Among men, independent predictors of HCV treatment uptake were homosexual identity and older age; among women, independent predictors included homosexual identity and an incarceration history. Despite increases in HCV treatment among Australian PWID between 1999 and 2011, uptake remains low. Strategies are required to increase the proportion of PWID assessed and treated for HCV infection to address the increasing burden of disease. Specific approaches that target women may also be warranted. Continued surveillance of HCV treatment uptake among PWID will be important to monitor the roll-out of simple, safe and more effective HCV treatments expected to be available in the future.

C-reactive protein triggers calcium signalling in human neutrophilic granulocytes via FcγRIIa in an allele-specific way.

C-reactive protein (CRP) binds to Fcγ-receptors, FcγRIIa (CD32) with high affinity and to FcγRIa (CD64) with low affinity. The binding to CD32 has been shown to be allele specific, that is, it binds to R/R131 but not to H/H131. Little is known about the cooperation of CRP and neutrophilic granulocytes (PMNs) in inflammatory reactions. The purpose of the present study was to examine CRP signalling in human PMNs, and whether this signalling is also allele specific. Cytosolic calcium of PMN was measured in a single-cell digital imaging system. Receptor expression and polymorphism were studied by real-time RT-PCR, flow cytometry and standard PCR. C-reactive protein induced cytosolic calcium signals in PMNs from homozygote R/R131 donors, but not in PMNs from heterozygote R/H131 donors. However, after the heterozygote PMNs had been incubated with IFN-γ (100 U/ml) for 2 h, both the proportion of cells responding and the size of the CRP-induced calcium signals increased. IFN-γ increased mRNA expression of CD64 about fivefold and surface protein expression of CD64 about fourfold. The calcium signal elicited by CRP was augmented by PMN adhesion to fibronectin, but almost totally abrogated by sphingosine kinase inhibitors. The signals were partly dependent on calcium influx. In conclusion, calcium signalling instigated by CRP in human PMN is FcγRIIa allele specific, as R/R131 responded to CRP, whereas R/H131 did not. However, increased expression of FcγRIa (CD64), stimulated by IFN-γ, can augment calcium signalling by CRP in low-responders. This suggests that the state of the PMNs, as well as the genetic origin, affect sensitivity for CRP.

Persistent environmental reservoirs on farms as risk factors for Campylobacter in commercial poultry.

Campylobacter is the most common known source of human bacterial enteritis in the developed world and poultry is considered the main source. Broilers often become colonized with Campylobacter during rearing, and then contaminate the farm environment. The objective of this study was to identify Campylobacter-positive environmental reservoirs on farms, as these pose a risk to broiler flocks becoming colonized with Campylobacter. We considered the temporal aspects of exposure and colonization. A longitudinal study monitored six conventional rearing farms over 2 years. The broiler flocks, catchers' equipment, vehicles, shed surrounds, shed entrance, other equipment, farm entrance, other animals, puddles, dead birds, mains water and drinkers were systematically sampled 2-4 times per flock. A multivariable generalized estimating equation model was used to assess associations between contaminated environmental sites and colonized broiler flocks. The associations were adjusted for confounders and other known risk factors. To further assess temporality of contamination, the sequence of contamination of the different environmental sites and the flocks was established. Contaminated shed entrances and anterooms, contaminated drinkers and shedding of Campylobacter by other animals such as cattle, dogs, wildlife and rodents were significantly associated with positive flocks. The reservoir of 'other animals' was also the reservoir most commonly positive before the flock became colonized. The other sites usually became contaminated after the flock was colonized.

Influence of season and geography on Campylobacter jejuni and C. coli subtypes in housed broiler flocks reared in Great Britain.

Geographical and seasonal variation in the incidence and prevalence of Campylobacter jejuni and C. coli in housed broiler flocks reared in Great Britain in 2004 to 2006 was investigated in this study. Ceca (30) from 797 flocks, not subject to prior partial depopulation and reared on 211 farms, were examined individually for the presence of Campylobacter spp. The best-fitting climatic factors explained approximately 46% of the prevalence of Campylobacter-colonized flocks at slaughter and consisted of a combination of temperature at slaughter, number of sunshine hours in placement month, and millimeters of rainfall in placement month. Positive flocks were more likely to be slaughtered between June and November than during the rest of the year and to be reared in northern Great Britain than in central or southern Great Britain. C. jejuni was identified in approximately 90% of flocks, and C. coli was present in 10% of flocks. The most common clonal complexes identified in 226 isolates typed by multilocus sequence typing (MLST) were ST-45, ST-21, ST-574, ST-443, and ST-828. Flocks slaughtered at the same time were more likely to have similar complexes, and ST-45 had a seasonal pattern, with the highest prevalence in June, and was also more likely to be present in flocks reared in northern Great Britain.

Long-term high-physiological-dose growth hormone reduces intra-abdominal fat in HIV-infected patients with a neutral effect on glucose metabolism.

OBJECTIVES: The aim of the study was to investigate the effect of long-term high-physiological-dose recombinant human growth hormone (rhGH) therapy on fat distribution and glucose metabolism in HIV-infected patients. METHODS: Forty-six HIV-infected Caucasian men on highly active antiretroviral therapy (HAART), with an age range of 21-60 years and no significant comorbidity, were included in this randomized, placebo-controlled, double-blind, single-centre trial. Twenty-eight subjects were randomized to 0.7 mg/day rhGH, and 18 subjects to placebo, administered as daily subcutaneous injections between 1 and 3 pm for 40 weeks. Endpoints included changes in visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT), limb fat mass, percentage of limb fat, plasma lipids, insulin resistance and glucose tolerance. RESULTS: VAT and trunk fat mass decreased significantly in the GH group compared with the placebo group [-19 cm(2) (-11%) vs. 12 cm(2) (6%), P=0.03, and -548 g (-9%) vs. 353 g (6%), P<0.01, respectively]. The beneficial fat redistribution in the GH group occurred without concomitant changes in subcutaneous fat at the abdomen or extremities. rhGH therapy was well tolerated. Insulin resistance, glucose tolerance, and total plasma cholesterol and triglycerides did not significantly change during intervention. CONCLUSIONS: Daily 0.7 mg rhGH treatment for 40 weeks reduced abdominal visceral fat and trunk fat mass in HIV-infected patients. This treatment appeared to be safe with respect to glucose tolerance and insulin sensitivity.

Q fever outbreak in Cheltenham, United Kingdom, in 2007 and the use of dispersion modelling to investigate the possibility of airborne spread.

We describe the investigation of an outbreak of Q fever in the town of Cheltenham, England. The outbreak was detected in June 2007, and prospective and retrospective case finding identified 30 confirmed or probable human cases. The investigation identified windborne spread of Coxiella burnetii from nearby sheep farms as the most likely source of infection. A telephone survey was conducted to identify risk practices at local farms. Subsequently the atmospheric dispersion model NAME was used to identify whether air from the identified farms with high risk practices had been carried into Cheltenham town centre during the risk period. Three high risk farms were identified and the modelling showed that air from all of these farms was carried over Cheltenham in the estimated risk period. The investigation resulted in an information campaign to farmers and production of improved advice for livestock farmers on reducing the risks of transmitting Q fever to humans.

Wind tunnel simulations of light and dark streaks on Mars.

Wind tunnel experiments have revealed a characteristic flow field pattern over raised-rim craters which causes distinctive zones of aeolian erosion and deposition. Comparisons of the results with Mariner 9 images of Mars show that some crater-associated dark zones result from wind erosion and that some crater-associated light streaks are depositional.

Factors influencing the presence and concentration of E. coli O157 and E. coli in farm waste on six cattle farms in North-West England.

AIMS: To investigate the factors influencing the presence and burden of Escherichia coli O157 in farm wastes. METHODS AND RESULTS: Wastes from six cattle farms were screened for the presence and concentration of E. coli O157 and E. coli on three occasions over a year and waste management data were collected. Sixty-three of 878 (7.1%) samples were positive for verocytotoxigenic Escherichia coli O157 and 664/875 (75.9%) for E. coli with detectable levels greater in fresh waste than in stored waste, pasture or dirty water. CONCLUSIONS: The turning/stirring of stored waste and the use of more than one store (allowing longer storage times) reduced the proportion of E. coli O157 positive samples. The presence of E. coli O157 significantly reduced from a high prevalence found in fresh faeces and stored waste to lower proportions in dirty water and pasture samples. Escherichia coli O157 was only detected on pasture when waste was spread from contaminated stores the day before sampling. A high prevalence of positive E. coli O157 samples were detected when cattle were re-housed. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings help to support the importance of treating and storing farm waste, as well as providing evidence for the level of dilution of E. coli O157 from fresh waste to recently spread pastures.

Verocytotoxigenic Escherichia coli O157 in animals on public amenity premises in England and Wales, 1997 to 2007.

At the request of the public health authorities, 31 public amenity premises in England and Wales containing animals of various species were investigated for the presence of verocytotoxigenic Escherichia coli (VTEC) O157 between 1997 and 2007, because of putative associations with human cases. VTEC O157 was confirmed in one or more species on 19 (61.3 per cent) of the premises. There were significant associations between the presence of VTEC O157 and the number of species sampled, the size of the enterprise, the presence of young cattle and the presence of adult pigs. E coli O157 was isolated from 305 (17.8 per cent) of 1715 samples taken from all the premises, and verocytotoxin genes were detected by PCR in 184 (98.4 per cent) of 187 representative isolates. On positive premises, the highest mean proportion of positive samples (29.0 per cent) was in cattle, followed by sheep (24.4 per cent), donkeys (14.6 per cent), pigs (14.3 per cent), horses (12.3 per cent) and goats (9.9 per cent). A high proportion of positive samples was obtained from camelid species sampled on three of the premises. The main phage types (PT) were 2 and 21/28, which were those most commonly isolated from human cases during the same period. A single PT was detected on 14 of the 19 positive premises, with up to six different species having the same PT.

Short communication: turbidity as an indicator of Escherichia coli presence in water troughs on cattle farms.

Studies have shown that water-drinking troughs are an important source of Escherichia coli infection on cattle farms, and a study was designed to provide farmers with an easy-to-use tool to monitor trough contamination and help determine when to empty and clean water troughs. A total of 164 water troughs were sampled on 33 cattle farms, and the on-farm turbidity tester results were found to be significantly correlated with laboratory turbidity results. Turbidity was associated with E. coli concentration, although the association was not linear. Emptying the troughs within a week of sampling was shown to reduce the turbidity score, but no linear association between time of emptying and E. coli concentration was discovered. A turbidity score of 4 was set as a cutoff point for when to clean a trough, yielding a sensitivity of 0.94 and a specificity of 0.03 for identifying a level of E. coli concentration that was more likely to contain E. coli O157 (>5,800 cfu/100 mL).

Experimental simulations of volcanic ash resuspension by wind under the effects of atmospheric humidity.

Ash deposited during volcanic eruptions can be resuspended by wind and become hazardous for health and infrastructure hours to decades after an eruption. Accurate resuspension forecasting requires accurate modelling of the threshold friction velocity of the volcanic particles (Uth*), which is the key parameter controlling volcanic ash detachment by wind. Using an environmental wind tunnel facility this study provides much needed experimental data on volcanic particle resuspension, with the first systematic parameterization of Uth* for ash from the regions Campi Flegrei in Italy and also Eyjafjallajökull in Iceland. In this study atmospheric relative humidity (and related ash moisture content) was systematically varied, from <10% to >90%, which in the case of the Eyjafjallajökull fine ash (<63 µm) produced a twofold increase in Uth*. Using the Campi Flegrei fine ash (<63 µm) an increase in Uth* of only around a factor of 1.5 was observed. Reasonable agreement with force balance resuspension models was seen, which implied an increase in interparticle adhesion force of up to a factor of six due to high humidity. Our results imply that, contrary to dry conditions, one single modelling scheme may not satisfy the resuspension of volcanic ash from different eruptions under wet conditions.

Prevalence and correlates of recent injecting drug use among gay and bisexual men in Australia: Results from the FLUX study.

BACKGROUND: While illicit drug use is prevalent among gay and bisexual men (GBM) in Australia, little is known about the factors associated with injecting drug use among GBM. METHODS: The Following Lives Undergoing Change (FLUX) study is a national, online prospective observational cohort investigating drug use among Australian GBM. Eligible participants were men living in Australia who were aged 16.5 years or older, identified as gay or bisexual or had sex with at least one man in the last year. We examined baseline data for associations between socio-demographic and behavioural characteristics and recent (last six months) injecting using log-binomial regression. RESULTS: Of 1995 eligible respondents, 206 (10.3%) reported ever injecting drugs and 93 (4.7%) had injected recently, most commonly crystal (91.4%) and speed (9.7%). Among recent injectors, only 16 (17.2%) reported injecting at least weekly; eight (8.6%) reported recent receptive syringe sharing. Self-reported HIV and HCV prevalence was higher among recent injectors than among other participants (HIV: 46.2% vs 5.0%, p < .001; HCV: 16.1% vs. 1.2%, p < .001). Recent injecting was associated with lifetime use of more drug classes (adjusted prevalence ratio (APR) = 1.31, 95% Confidence Interval (95%CI) 1.21-1.41), longer time since initiating party drug use (APR = 1.02, 95%CI 1.01-1.04), greater numbers of sex partners (2-10 sex partners: APR = 3.44, 95%CI 1.45-8.20; >10 sex partners: APR = 3.21, 95%CI 1.30-7.92), group sex (APR = 1.42, 95%CI 1.05-1.91) and condomless anal intercourse with casual partners (APR = 1.81, 95%CI 1.34-2.43) in the last six months. CONCLUSIONS: Observed associations between injecting and sexual risk reflect a strong relationship between these practices among GBM. The intersectionality between injecting drug use and sex partying indicates a need to integrate harm reduction interventions for GBM who inject drugs into sexual health services and targeted sexual health interventions into Needle and Syringe Programs.

Secretion of glucagon from the isolated, perfused canine pancreas.

Using the isolated, perfused canine pancreas preparation, previously described, the interrelationship of the secretion of pancreatic glucagon and insulin was studied after stimulation with glucose, gastrointestinal hormones, and the amino acid arginine. The results confirm the concept that pancreatic glucagon is a hormone of "glucose need" and suggest that it may be important in a moment to moment control of glucoregulation. The secretion of pancreatic glucagon was stimulated after infusion of gastrin, pancreozymin, and arginine, while no increase was associated with secretin infusion. The magnitude of the increase was closely related to the glucose concentration present in the perfusion medium, being higher and more pronounced during perfusion with low concentrations of glucose (25 mg/100 ml or 50 mg/100 ml). Stimulation of insulin secretion was seen after glucose, gastrin, pancreozymin, secretin, and arginine. The magnitude of the increase was again closely related to the glucose concentration present, this time being higher and more pronounced during perfusion with high glucose concentrations (150 mg/100 ml). Secretion of both pancreatic hormones always followed a biphasic response pattern after the stimuli mentioned, similar to the characteristic release pattern previously described for insulin after an increment in glucose concentration. In order to elucidate whether endogenous pancreatic glucagon possesses an insulinogenic action, as it has been shown to be the case with the administration of exogenous pancreatic glucagon, the time interrelationship of the secretion of pancreatic glucagon and insulin was investigated by determining the initial rise of the hormones after stimulation with gastrin, pancreozymin, and arginine. The rise of glucagon and insulin occurred simultaneously, i.e. inside a 10 sec period. This does not, however, exclude with certainty an insulinogenic role of pancreatic glucagon.

Adrenergic receptors and the secretion of glucagon and insulin from the isolated, perfused canine pancreas.

During perfusion with a glucose concentration of 150 mg/100 ml, infusions of l-epinephrine, l-norepinephrine, and d-l-isoproterenol at physiological concentrations of 2 ng/ml for 9 min stimulated secretion of glucagon in a monophasic response pattern, in contrast to the biphasic response normally encountered after glucagon releasing stimuli as previously reported from our laboratory (1971. J. Clin. Invest.50: 2123). Glucagon was stimulated in spite of a glucose concentration which in itself effectively inhibits glucagon release. Release of insulin was strongly inhibited after epinephrine and norepinephrine, and strongly stimulated after isoproterenol. During perfusion with a glucose concentration of 25 mg/100 ml, secretion of glucagon was greatly accentuated by the catechols investigated. Secretion of insulin remained unchanged after epinephrine and norepinephrine, but was stimulated by isoproterenol. The catechol induced glucagon release was suppressed or abolished when the beta-blocking agent propanolol was simultaneously infused at a concentration of 1 muM, while the inhibition of insulin became further accentuated. The catechol induced glucagon release remained unchanged when alpha blockade was performed using either phentolamine (1 muM) or dibenzyline (10 mug/ml), while the inhibition of insulin was converted to a stimulation. Evidence is thus presented that both the alpha cells and the bet cells are under the influence of adrenergic substances, the stimulation of glucagon release being mediated through a beta receptor and the inhibition of insulin release being mediated through an alpha receptor.

Phase II trial of suramin in patients with advanced renal cell carcinoma: treatment results, pharmacokinetics, and tumor growth factor expression.

Twenty-six patients with advanced renal cell carcinoma were treated with suramin administered by continuous infusion, with dosing determined by a nomogram. One patient achieved a partial response and five patients achieved a minor response or had stable disease for > 3 months. Toxicities included an immune-mediated thrombocytopenia in one patient and Staphylococcus sepsis that was not associated with neutropenia in five patients. Pharmacokinetic parameters were determined by the ADAPT II MAP-Bayesian parameter estimation program. Patient data were fit using a two-compartment open model and first-order rate elimination. This showed a wide interpatient variation in time to target level (median, 13.8 days), volume of distribution (median, 15.2 liters/m2), and t1/2-beta (median, 20.6 days). The patients who achieved a partial response, minor response, or stable disease had a slower elimination rate of suramin, compared to patients with progressive disease. Tumor specimens were obtained prior to therapy and were analyzed for the production of five different growth factor-specific RNA transcripts. These included transforming growth factor alpha, acidic fibroblast growth factor, basic fibroblast growth factor, and platelet-derived growth factor types A and B. No difference in the pattern of growth factor expression was seen in tumors of responding and nonresponding patients. Suramin does not have significant antitumor activity in renal cell carcinoma. The wide variability in pharmacokinetics suggests that individual dosing should be used in future trials of suramin for treatment for other malignancies. Pertinent corollary studies of tumor biology and clinical pharmacology should be included whenever possible in clinical trials in patients with renal cell carcinoma.

Use of adaptive control with feedback to individualize suramin dosing.

Suramin is the first putative growth factor inhibitor in clinical trial that has demonstrated antitumor activity. Administration of suramin is complicated by a narrow therapeutic index and significant interpatient variability of measured pharmacokinetic parameters. Because both antitumor response and dose-limiting toxicities are related to plasma suramin concentration profiles, individualized dose schedules are required for optimal administration of the compound. In this report, the use of optimal sampling theory to derive sparse data monitoring and control strategies for use with suramin is described. A fixed rate continuous infusion schedule was used in seven patients, and the time to peak concentration (280-300 micrograms/ml) ranged from 7.7-21 days (mean, 13.2 days) with a decline to 150 micrograms/ml in 3-22 days (mean, 11 days). An initial population pharmacokinetic model was fit using a maximum likelihood algorithm. The mean volume of the central compartment was 4.5 +/- 6.7 liters/m2, volume of the peripheral compartment 10.6 +/- 1.4 liters/m2, distributional half-life 25 +/- 5.4 h, and elimination half-life 29.7 +/- 6.9 h. The terminal half-life was shorter than previously reported. These parameters were used as the initial population model for an iterative 2-stage analysis. The resulting distributional half-life of 22.3 +/- 2.7 h and elimination half-life of 28.2 +/- 5.0 h were similar, reflecting the intensive sampling. The iterative 2-stage analysis model was then used to determine the optimal sampling times and to simulate 20 data sets for a protocol designed to maintain plasma concentrations in a defined concentration range. This strategy is currently under investigation in phase I clinical trials.

The protein composition of rat parotid saliva and secretory granules.

Rat parotid saliva was collected by surgical cannulation of the ducts and stimulation with pilocarpine; The secreted salivary proteins were resolved on columns of DEAE-Sephadex into five major Fractions, I-V, which were characterized by polyacrylamide disc gel electrophoresis, amino acid analyses and enzymatic assay. Rat parotid secretory granules were isolated by density gradient centrifugation and lysed in hypotonic buffers. Granule content proteins were resolved and examined by the same techniques as for secreted proteins. In both experiments, Fraction I contained RNAase and a major unidentified protein, M1, Fraction II contained the isoenzymes of amylase; DNAase was present in Fraction III and, to a lesser degree, in Fraction IV. The proportions of the enzyme-containing peaks were the same in saliva and granule contents. Fractions IV and V contain proteins of unknown function; Fraction IV contains exceptionally high levels of glutamic acid, glycine and proline in its protein moieties and approx. 6-8% neutral sugars.

Demonstration of a class of proteins loosely associated with secretory granule membranes.

It is shown, in this study, that rat secretory granule membrane preparations, as prepared by the method of Amsterdam et al. [(1971) J. Cell Biol. 50, 187-200], contain a protein fraction which is removed by washing in isotonic medium. This fraction contains unusually high levels of Pro, Gly and Glx, and appears to label rapidly if the rats are pulsed with [14-c] amino acids prior to removal of the glands. The fraction, which may represent specifically adsorbed secretory protein(s) or peripheral membrane protein, is significant to investigators using this model system to study secretory phenomena.