Higher Mean Activity Research Articles

Evaluating a novel 24-hour rest/activity rhythm marker of preclinical β-amyloid deposition.

To compare sleep and 24-hour rest/activity rhythms (RARs) between cognitively normal older adults who are β-amyloid-positive (Aβ+) or Aβ- and replicate a novel time-of-day-specific difference between these groups identified in a previous exploratory study. We studied 82 cognitively normal participants from the Baltimore Longitudinal Study of Aging (aged 75.7 ± 8.5 years, 55% female, 76% white) with wrist actigraphy data and Aβ+ versus Aβ- status measured by [11C] Pittsburgh compound B positron emission tomography. RARs were calculated using epoch-level activity count data from actigraphy. We used novel, data-driven function-on-scalar regression analyses and standard RAR metrics to cross-sectionally compare RARs between 25 Aβ+ and 57 Aβ- participants. Compared to Aβ- participants, Aβ+ participants had higher mean activity from 1:00 p.m. to 3:30 p.m. when using less conservative pointwise confidence intervals (CIs) and from 1:30 p.m. to 2:30 p.m. using more conservative, simultaneous CIs. Furthermore, Aβ+ participants had higher day-to-day variability in activity from 9:00 a.m. to 11:30 a.m. and lower variability from 1:30 p.m. to 4:00 p.m. and 7:30 p.m. to 10:30 p.m. according to pointwise CIs, and lower variability from 8:30 p.m. to 10:00 p.m. using simultaneous CIs. There were no Aβ-related differences in standard sleep or RAR metrics. Findings suggest Aβ+ older adults have higher, more stable day-to-day afternoon/evening activity than Aβ- older adults, potentially reflecting circadian dysfunction. Studies are needed to replicate our findings and determine whether these or other time-of-day-specific RAR features have utility as markers of preclinical Aβ deposition and if they predict clinical dementia and agitation in the afternoon/evening (i.e. "sundowning").

Association of ankylosing spondylitis activity indicators in a Russian population of patients with STAT4 rs7574865 gene polymorphism

Family and twin studies have shown that ankylosing spondylitis (AS) has a hereditary nature that is based on a strong association with the leukocyte antigen HLA-B27. However, only 1–5% of HLA-B27 carriers develop AS, which indicates that there are other genetic markers involved in the formation of a predisposition to this disease. A number of genome-wide association studies have convincingly confirmed the role of the STAT4 gene. This gene encodes the protein – the signal transducer and activator of transcription (STAT) protein, which is a predisposing factor for the development of many autoimmune diseases. There are not so many studies of the relationship of STAT4 polymorphisms to the predisposition to AS, and there are no these studies regarding the Russian population.Objective: to study whether there is a possible association of STAT4 rs7574865 gene polymorphism with the predisposition to AS and to assess the activity of this disease using BASDAI and ASDAS scores in the Russian patient population.Patients and methods. A cohort of 203 individuals, including 100 patients (79 men and 21 women) with AS, and 103 healthy volunteers (a control group) was surveyed. Age, gender, duration, and specific features of AS onset, ESR, and CRP levels were assessed. BASDAI and ASDAS scores were calculated to evaluate disease activity.Results and discussion. There was a significant relationship between STAT4 polymorphism and C-reactive protein (CRP) levels and BASDAI and ASDAS-CRP scores. The TT genotype carriers had significantly higher mean activity indices compared to the GG (p=0.001) and GT (p=0.005) genotype carriers for CRP, BASDAI (p=0.0001 and p=0.009, respectively) and ASDAS-CRP (p=0.009 and p=0.001, respectively). High disease activity (BASDAI >4 and ASDAS-CRP >3.5) was also associated with the high frequency of the T allele (p=0.046 and p=0.004, respectively). The value of STAT4 rs7574865 gene polymorphism in the pathogenesis of autoimmune diseases is confirmed by a study in which the T allele in STAT4 rs7574865 enhances mRNA transcription and protein expression. Italian authors have shown that there is a relationship between the minor T allele of rs7574865 and the high risk of arthritis. We have previously established a relationship between the T allele and the predisposition to diffuse systemic scleroderma, interstitial lung damage, and elevated anti-topoisomerase I antibody levels.Conclusion. The present study has shown for the first time a significant association of STAT4 rs7574865 polymorphism with the main AS activity indicators: CRP levels, BASDAI and ASDAS-CRP scores. The studied polymorphism may be a new genetic marker for predicting the severity of AS.

Radiological toxicity of some fish and meat tissues consumed in southwestern Nigeria

ABSTRACTThe activity concentrations of natural radionuclides in 30 fish tissues and 30 meat organs have been determined using high purity germanium (HPGe) detector. For the fish tissues, the mean activity concentrations of 238U and 232Th were highest in Catfish (Clarias gariepinus) with values of 5.31 ± 1.30 and 6.09 ± 0.91 Bq/kg, respectively. The lowest mean activity concentrations of 238U and 232Th were seen in Titus (Scomberomorus tritor) and Croaker (Micropogonias undulatus), Croaker with values of 1.51 ± 2.08 and 64.42 ± 6.33 Bq/kg, respectively. The mean activity concentration of 40K was highest in Micropogonias undulatus and lowest in Tilapia (Oreohronis niloticus) with values of 64.42 ± 6.33 and 6.53 ± 0.98 Bq/kg. For the meat organs, the highest mean activity concentration of 238U, 232Th, and 40K was highest in kidney, liver, and heart, respectively with values of 2.82 ± 0.47, 4.57 ± 0.69, and 52.07 ± 7.81 Bq/kg. Small intestine had the lowest mean activity concentrations of 238U and 232Th with values of 1.14 ± 0.16 and 0.89 ± 0.08 Bq/kg, respectively. Beef had the lowest mean activity concentration of 40K with a value of 17.61 ± 2.14 Bq/kg.

Comparative Investigation of the Antibacterial and Antifungal Potentials of the Extracts of Watermelon (Citrullus lanatus) Rind and Seed

Aim: To investigate the antibacterial and antifungal potentials of the crude ethanol and aqueous extracts of watermelon (Citrullus lanantus) rind and seed. Study Design: The fruits were purchased from a local market and identified in the Department of Plant Science and Biotechnology, Michael Okpara University of Agriculture Umudike, Nigeria by a taxonomist. The rind and seed samples were extracted using ethanol (95%) and water and the crude extracts screened for antibacterial and antifungal potentials. Place and Duration of Study: Department of Biochemistry, Michael Okpara University of Agriculture Umudike, Nigeria and National Root Crops Research Institute Umudike, Nigeria, between August, 2014 and November, 2014. Methodology: The ethanol and aqueous extracts of watermelon (Citrullus lanantus) rind (EER and AER) and seed (EES and AES), each at a concentration of 100 mg/ml, were investigated by welldiffusion method for activity against ten pathogens. Results: The EER exhibited the highest activity against the bacterium, Esherichia coli (6.0) and the fungus, Candida albican (4.0). The least activity was in the EES against the fungus, Trichosporo bepelli (0) followed by EER and AES against the bacterium, Staphylococcus aureus (1.0). For the Original Research Article Cemaluk; EJMP, 9(4): 1-7, 2015; Article no.EJMP.18142 2 bacterial strains, the highest mean activity (4.0) and mean susceptibility (4.50), respectively was in the EER and Esherichia coli whereas the least mean activity (3.0) and mean susceptibility (1.50), respectively was in AES and Staphylococcus aureus. For the fungal strains, the highest mean activity (2.5) and mean susceptibility (3.0), respectively was in the EER, AER, AES and Candida albican whereas the least mean activity (1.25) and mean susceptibility (1.25) was in EES and Trichosporo bepelli. The activity against the studied pathogens however was higher in the EE than in the AE of the rind and seed, suggesting the preference to the EE for higher pharmacologic activity. Conclusion: The extracts (EER, AER, EES and AES) exhibited activity against the tested strains, especially Escherichia coli and Candida albicans. The study underscores the overriding potency of EER against the bacterium, Escherichia coli and the fungus, Candida albicans, and the nonsusceptibility of the fungus, Trichosporo bepelli to EES. Further works, however are needed to validate reliability and possible exploitation in nutraceutical formulations and in ethnomedication.

Activity of neutrophil elastase reflects the progression of acute pancreatitis

Objective. Neutrophil elastase (NE) concentration is associated with progression of acute pancreatitis (AP), but measuring total NE concentration includes biologically inactive NE. This study aims to investigate the relationship between NE activity and the aetiology and severity of AP and associated organ failure. Methods. Seventy-five patients admitted to our surgery department with a first episode of AP during 2004–2005 were age- and sex-matched to 20 healthy volunteers (controls). NE activity was assessed using venous blood samples obtained on patient admission and after 1, 2 and 14 days. One sample was also taken from each control. ANOVA was used for statistical comparison between groups. Results. Baseline NE activity (geometric mean; 95% confidence intervals) differed between patients (58.6 nM of substrate 7-amino-4-methylcoumarin [AMC]/hour; 48.52–70.72) and controls (31.5 nM AMC/hour; 25.5–39.0) (p = 0.0003), and did not correlate with time between symptom onset and admission. Patients with alcohol-induced AP demonstrated higher mean activity (59.1 nM AMC/h; 44.7–78.2) than those with gallstone-induced AP (41.7 nM AMC/h; 33.9–51.4) (p = 0.0496). NE activity was higher overall in patients with predicted severe AP (60.9 nM AMC/h; 48.0–77.2) than in those with predicted mild AP (42.1 nM AMC/h; 34.9–50.8) (p = 0.027). Patients with respiratory failure had higher NE activity (82.5 nM AMC/h; 57.5–118.4) than those without (43.9 nM AMC/h; 37.6–51.3) (p = 0.0024). Conclusions. NE activity was associated with predicted severity of AP and AP-associated respiratory failure. Specific NE inhibitors may have therapeutic potential in acute pancreatitis.

Abstract 4544: On using textural information from longitudinal PET scans for predicting tumor response

Abstract Purpose: Early therapy response prediction, employing biomarkers such as [F-18]-fluorodeoxyglucose (FDG) followed with positron emission tomography (PET) for imaging the tumor metabolic activity, is a very actively researched topic. Traditionally, only the first order intensity based feature estimates extracted from the longitudinal scans are used for the response evaluations. Nonetheless, lesion heterogeneity computed from the higher order textures of the baseline scan prior to treatment has been recently found to be correlating well with the final outcome. The aim of this study is to establish the significance of tumor texture in follow up evaluations. Methods: 15 patients suffering from metastatic colorectal cancer and treated with cetuximab were selected for the study. Baseline FDG PET scans were acquired prior to treatment and the follow up scanned at 1 week after 1st dose of treatment was investigated for early response. One to five lesions were identified per patient. Intensity based features (IF) computed from the standardized uptake value (SUV) image include SUVmax (maximum activity), SUVmean (mean activity), SUVpeak (highest mean activity in 1mL sphere within tumor), tumor lesion volume (TLV) in mL, total lesion activity (TLA), TLA = SUVmean x TLV in SUVmL and total lesion energy (TLE), TLE = SUVmean^2 x TLV in SUV^2mL. Texture covariates (TF) estimated include 11 activity level run length matrix (ALRL) features, 11 activity level size zone matrix (ALSZ) features, 7 activity level co occurrence matrix (ALCM) features, 5 activity level difference matrix (ALDC) features and 19 activity level histogram (ALHS) features. Response indices (RI) were computed as the % change with respect to baseline after adding up covariates over all lesions per patient under study. The dynamic range of IF was investigated in baseline. A Cox proportional hazards regression model was fit with RIs and the time dependent receiver operating characteristics (ROC) was determined. Leave one-out cross validation (LOCV) was performed to investigate the fitting of the model. The concordance measure with the time to progression (TTP) was determined in each of the scenarios. Results: The baseline IF dynamic ranges are listed below representing (Median ± Standard Deviation, Minimum - Maximum) the respective covariates. SUVmax(6.33 ± 2.34, 2.40 - 12.28). SUVpeak(4.86 ± 2.01, 1.64 - 10.52). SUVmean(4.05 ± 1.52, 1.61 - 8.39). TLV(5.71 ± 155.91, 0.48 - 1182.42). TLA (29.58 ± 872.80, 2.11 - 6620.88). TLE (152.79 ± 5138.32, 3.55 - 38963.30). Cox model on LOCV with the IF only covariate set and the IF+TF set resulted in concordance of 0.6570 and 0.6764 resp. Conclusion: The results with the current data denote an added value in using textural information for therapy response evaluation. Moreover, therapy response could be predicted as early as 1 week after 1st dose of treatment from the feature estimates. Acknowledgements: This work is financially supported by KU Leuven's Concerted Research Action GOA/11/006, Research Foundation - Flanders (FWO), IWT Agency for Innovation by Science and Technology - Applied Biomedical Research (TBM) project 070717 and IBBT-KU Leuven Future Health Department. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4544. doi:1538-7445.AM2012-4544

Abstract P183: Parents Play Significant Role in the Gender Differences Associated with Physical Activity in Elementary Students

BACKGROUND It has been proven that males engage in physical activity more than females starting at a young age. The goal of this study was to investigate gender differences based on parenting behaviors such as the frequency with which parents send their children out to play. METHODS Parents of children participating in a free cardiovascular risk-screening program (CARDIAC Project) completed a behavioral survey. Children (n =472; 43.3% female) who were enrolled in elementary school participated in the study. Parents provided information about children’s physical activity and their own ways in which they provided support of activity at home. Children’s participation in 12 activities was captured by total number of minutes per week. A combined mean activity score was calculated by summing the children’s total time across all of the activities. Parent behavior , specifically the frequency at which parents send their children outside to play was captured using a Likert scale where “1” represented never and “5” represented daily. Child gender and the amount of time allowed outside for play were then entered into a linear regression model to examine their role as potential predictors of child activity. RESULTS A significant gender difference (p<.001) was noted in children’s total activity time with boys (n = 237; 751 minutes/week) exhibiting higher mean activity each week than girls (n = 229; 521 minutes/week). Child gender and the amount of time allowed outside to play significantly predicted children’s activity levels overall. This model explained 28.9% of the variance in children’s activity levels (F = 20.25 (2); p<.001). Specifically, girls had less opportunity (3.75) than boys (4.05) to play outside. CONCLUSION A factor behind the lesser physical activity in female adolescents is significantly related to the decreased opportunity to play outside. Additional parenting practices will be shared if presented. In conclusion, parent behavior plays a significant role in the proven gender differences with childhood physical activity.

Outcome of Lupus nephritis-A 5-year Analysis

Objective: To investigate the long-term outcome of class IV lupus nephritis (LN) and to analyze its prognostic factors. Materials and Methods: We performed a retrospective chart review study of 157 patients with LN between January 1986 and June 2004 in Chang Gung Memorial Hospital at Kaohsiung. All of these LN patients fulfilled the systemic lupus erythematosus classification criteria of the American College of Rheumatology and had histopathological findings of LN. Only those pathology-proved subjects with class IV by 2003 ISN/RPS classification were recruited. We reviewed the charts and collected the demographic data, serological parameters, and treatment courses of subjects recruited. The end point of renal outcome were doubling of serum creatinine (I) and end stage renal disease (ESRD)/death (II) within 60 months after renal biopsy Results: A total of 75 subjects were recruited, including 13 male and 62 female. Mean age was 25.9±9.7 year. Five years after renal biopsy, 16 subjects (21.3%) developed outcome I and 15 subjects (20.0%) developed outcome II. Those who did not develop outcome I had higher mean (14.5±2.1) activity index (AI) than that (13.1±2.5) of those did (HR=0.55, CI=0.35-0.87, p=0.01). For those who did not develop outcome II, the mean AI was also higher than those who did (14.4±2.2 vs.13.5±2.3, HR=0.67, CI=0.44-1.00, p=0.05). Conclusions: The 5-year renal survival of current series, in terms of ESRD/death, was 80% and this was not as favorable as those reported in the other investigations. High activity index at biopsy is a predictor of favorable prognosis of long-term renal outcomes in case that aggressive treatment had been given.

Field studies of eelpout (Zoarces viviparus L.) from Polish coastal waters (southern Baltic Sea)

The aim of the presented studies was to detect the possible effects of contaminants on the physiological and biochemical parameters of eelpout females from the southern Baltic. Eeelpout was sampled in Polish coastal waters during November 2001, 2002 and 2003. The integrated studies included measurements of selected biomarkers in fish as well as the analysis of female reproductive capacity and fry malformation frequencies in relation to environmental conditions in examined areas. The mean values of relative fecundity (RF) and embryo somatic (ESI) indexes were the highest at the reference site. The frequency of females carrying dead and malformed fry was the highest at selected sites from the outer and inner part of the Gulf of Gdansk. The highest mean activity levels of muscular AChE were noted in fish sampled at the reference site and one site from the outer part of the gulf, whereas liver GST activity was the highest in samples from other site from the outer part of the gulf and the reference site. The results of trace metals analyses in fish muscle and liver did not indicate any substantial differences in the mean tissue concentrations between samples from contaminated sites and the reference site. The concentrations of PCBs, HCHs and DDTs in liver were markedly higher at three contaminated sites in comparison with the other sites. A similar pattern was observed in muscle tissue. Based on the preceding evidence, it cannot be concluded unequivocally that these studies on the physiology, biochemistry and contaminant concentrations of eelpout females provide evidence that the contaminants present in the coastal areas of the Polish part of the southern Baltic Sea have a harmful impact on this species.

Electromyographic characteristics of deep, thoracic paraspinal musculature

Introduction Few researchers have examined the recruitment and activation patterns of deep, thoracic paraspinal muscles. Raw EMG signals from intra-muscular electrodes from different sites within the same muscle are highly variable in magnitude, 1 making direct comparison of raw, fine-wire EMG data from multiple thoracic sites invalid. To overcome this problem, EMG data should be normalised using maximal voluntary contraction (MVC), but the best method for eliciting MVC in deep, thoracic paraspinal muscles is unknown. Design Single cohort, repeated measures design. Methods Fine-wire, bi-polar intramuscular electrodes were inserted, under real-time ultrasonic guidance, into the deep paravertebral muscle mass underlying three adjacent sites in the thoracic PVG regions of 12 subjects (mean age=25.42 years, range=22–43). EMG activity was recorded under passive and active conditions. Two tasks, active prone extension and holding weights (2kg) in outstretched arms, were expected to elicit MVC. Results There were large variations in EMG activity within and between individuals. Peak amplitudes for individual sites were found under every condition, except resting prone. There was a significant difference between activity under the different conditions ( F 3.1,102.3 =0.04). The lowest mean EMG activity occurred during resting prone (0.11mV, SD=0.12), and the highest mean activity was recorded for passive rotation to the opposite side (0.51mV, SD=0.70). The mean amplitude for holding weights (0.42mV, SD=0.76) was higher than for active thoracic extension (0.34mV, SD=0.48), and there was a weak, inverse correlation ( r =−0.23) between the mean values recorded from these tasks. Conclusions EMG activity from deep, thoracic paraspinal muscles was highly variable, and no single task elicited MVC from all sites. The highest EMG activity occurred during passive rotation to the opposite side, which may be related to the proposed role of these muscles as spinal stabilisers. Active extension and holding weights in outstretched arms appeared to activate the muscles in different ways. EMG values should be normalised to the peak amplitude of each site.

Inhibition of the Tyrosine Kinase, Syk, Analyzed by Stepwise Nonparametric Regression

A set of 538 inhibitors of the tyrosine kinase, Syk, including purines, pyrimidines, indoles, imidazoles, pyrazoles, and quinazolines, has been analyzed using a stepwise nonparametric regression (SNPR) algorithm, which has been developed for QSAR studies of pharmacological data. The algorithm couples stepwise descriptor selection with flexible, nonparametric, kernel regression, to generate structure-activity relationships. A further 371 molecules have been used as a test set to evaluate the models generated. Descriptors were selected using an internal monitoring set, and models were assessed using 10% of the principal (538-compound) data set, selected randomly, as an external validation set. The best model had a Q(2) of 0.46 for the external validation set. Test set predictions were significantly less accurate, partly due to the higher mean activity of the test molecules. However at a more coarse-grain level the SNPR models classified active molecules accurately, giving good enrichments. The data sets are difficult to model accurately and SNPR performs better than multilinear regression and a neural network analysis. In the additive implementation of SNPR multidimensional models are considered as a sum of single dimensional regressions. This makes the resultant models easily interpretable. For example, in the most predictive SNPR models, there is a clear nonlinear relationship between hydrophobicity (AlogP98) and inhibitory activity.

The lipolytic activity of Thermomyces lanuginosus strains isolated from different natural sources

Abstract The ability of 144 Thermomyces lanuginosus wild strains isolated from biohumus, mushroom and garden composts, decayed leaves, hazelnuts, and raw coffee beans to hydrolyze synthetic (tributyrin, Tween 20, Tween 40, Tween 60, and Tween 80) and natural fatty substrates (sunflower, soybean, rapeseed and corn oil) was evaluated, and whether the lipolytic activity depended on the isolation source determined. All strains incubated at 55 °C on solid media containing 1% synthetic and 15% natural fatty substrates hydrolyzed both types of substrate. Mean lipolytic activity on natural substrates was significantly higher than on synthetic substrates. The highest mean activity index was noted after growth on sunflower oil, followed by soybean oil and tributyrin; indices on other fatty substrates were low. Strains isolated from raw coffee beans showed the highest mean index, followed by those from biohumus and garden compost; the lowest index being for strains isolated from hazelnuts. Thus, the lipolytic activity index depended on the specific fatty substrate and the source of the isolates.

Aging Alters Properties of the Circadian Pacemaker Controlling the Locomotor Activity Rhythm in Males of Drosophila Nasuta

Effects of aging on the circadian rhythm of locomotor activity in males of Drosophila nasuta were investigated. The adult life of males was divided in 1-3 stages according to spontaneous changes in free-running period x in constant darkness (DD): stage 1, days 1-19; stage 2, days 20-36; stage 3, days 37-43. Stage 1 was characterized by a bimodal activity pattern with a short light-induced morning peak and a prolonged evening peak when the flies were entrained to light-dark cycles of 12 hours of light, 12 hours of darkness (LD 12:12). The morning peak had a phase angle difference Ψm (Ψ, the time from lights on in LD 12:12 cycles to the onset of morning peak) of about 0.1h, while Ψe (Ψ of evening peak) was about 9h at stage 1. The transient morning peak was curtailed at the end of stage 1. At stage 2, the Ψe was about 10h, and the activity end was delayed by an addition of about 3h of activity in the scotophase. The changes in W during DD free runs were determined in two groups of flies: flies reared in LD 12:12 and flies reared in DD. In both groups, W increased from about 23h at stage 1 to about 25h at stage 2. Stage 3 was characterized by arrhythmicity associated with highest mean activity level (total number of passes/fly/day) in the entrained and both free-running groups. The mean activity level increased significantly from stage 1 to stage 3 in all three groups of flies.

Comparative efficacy of platidiam and carboplatin against tumor cells of human ovarian primary carcinomas

The efficacies of platidiam and carboplatin against human ovarian cancer cells (21 samples) were compared usingthe in vitro MTT test. Sampling analysis showed a some-what higher mean activity of carboplatin in comparison with platidiam in the dose range equivalent to 0.1 to 3.0 therapeutic doses. The efficacy of carboplatin was found to increase more rapidly with dosage build-up than that of platidiam.

A Comparison Between Fibronectin and Matrigel Pretreated ePTFE Vascular Grafts

Two distinct series of experiments were performed to compare the behavior of ePTFE vascular grafts coated with basement membrane gel to that of identical grafts coated with fibronectin. Bilateral carotid interposition grafts (10 cm long) were interposed in 16 conditioned mongrel dogs. In the first series of experiments (n = 10), each graft was seeded with radiolabeled endothelial cells and initial endothelial cell adherence was determined. Following restoration of blood flow in the grafts, endothelial cell retention was measured for 24 hours. Seeding efficiency was 66.48% (+/- 13.2) for fibronectin-coated grafts and 56.58% (+/- 13.51) for gel-coated grafts. There was a slow, constant loss of activity during the first 90 minutes of imaging, and at 24 hours of observation the activity remaining on the fibronectin-coated graft was 13.2 +/- 3.98% of the initial graft activity. Although the basement membrane gel had a higher mean activity at 24 hours (18.9 +/- 7.22%), the difference was not statistically significant at any interval. In the second series of animals (n = 6), radiolabeled platelets were injected within 60 minutes following restoration of flow. Total platelet activity on the explanted grafts was 3.36 (+/- 1.35) x 10(5) counts per gram/0.2 minute for the fibronectin-coated grafts. The gel-coated grafts had 2.74 (+/- 1.33) x 10(5) counts per gram/0.2 minute, a difference that was not statistically significant. Thus, despite its theoretical appeal, basement membrane gel was no better than fibronectin in increasing endothelial cell adherence and retention, and the resulting flow surface of grafts treated with either compound appeared to attract platelets to an equal degree.

Milk Lipoprotein Lipase Distribution in the Major Fractions of Bovine Milk

Raw, bovine bulk tank milk and milks from selected cows were separated by ultracentrifugation into four major fractions: casein, sloughed membrane material, serum, and milk fat globule membrane. Milk lipoprotein lipase activity was measured by the pH stat method and protein determinations were made by the Lowry procedure for each of the four fractions in order to calculate specific activity (units per milligram of protein). In six farm-cooled bulk milk samples stored ⩽ 24h, casein had a significantly higher milk lipoprotein lipase total activity, 35.66 units/ml of milk, than all of the fractions. Serum had the next highest activity with 11.69 units/ml of milk. Fluff and milk fat globule membrane had activities of .80 and .41 units/ml of milk, respectively. The specific activity of the fluff was 3.3 milk lipoprotein lipase units/mg of protein, which was significantly higher than the casein and serum fractions in pooled milk. Milks from five cows in midlactation were assayed individually for milk lipoprotein lipase activity and protein content immediately after milking and after 12, 24, 48 and 72h of cold (4°C) storage. Fresh warm milk was characterized by the absence of fluff. Casein had the highest mean activity (29.91 units/ml), followed by serum (10.25 units/ml) and milk fat globule membrane (.26 units/ml) in the warm milk from the individual cows. Upon cooling to 4°C, significant increases in enzyme activity in the fluff and milk fat globule membrane fractions were observed at 12h. In the cooled milks, milk lipoprotein lipase units/mg of protein for casein, fluff, and milk fat globule membrane were not significantly different but were significantly higher than the serum fraction. The specific activity of the fluff following cooling and storage of fresh, raw individual cow's milk suggests an association of the enzyme with sloughed membrane material.

Stability of insecticide resistance in the peach‐potato aphid, Myzus persicae (Sulzer)

AbstractAnholocyclic Myzus persicae (Sulz.) from the glasshouse and field can be classified into six variants, each with a characteristic carboxylesterase activity and consequent resistance to carbamate and organophosphorus insecticides. Overlapping activity distributions prevent unequivocal identification of an individual from measurements of its enzyme activity, but this may be done by cloning and measuring the frequency distribution of the enzyme activity in its progeny. Although each of the four lowest esterase variants has a frequency distribution with a single peak, only the susceptible (USLL) is best described by a single Normal distribution. Those of the other three clones (MSIG, French R and T1V) correspond better with two Normally‐distributed components. However, these are not well separated and the lower component accounts for only 10‐25% of the individuals. The very resistant clones from glasshouses have higher mean activities but with very broad distributions covering the whole range observed in this aphid. These broad distributions have peaks corresponding to those of the less resistant variants and arise from the appearance at each generation of a small proportion of individuals with much less active enzyme than their parents. Careful monitoring of the changes in activity between parents and offspring of the most resistant variant (clone G6) showed that complete loss of resistance can occur either in a single step or over several generations, and that below a threshold value, reversion to higher levels is very rare. Such reversion could only be detected by selection, with insecticide, of large clonal populations from an individual that had lost activity. High esterase activity was not stabilised by breeding for 16 generations only from individuals with high esterase activity, and is probably maintained in glasshouses by continuous exposure to insecticides. Spontaneous loss of esterase activity and resistance was observed only in glasshouse populations.

RATIONAL CHOICE OF PENICILLINS AND CEPHALOSPORINS BASED ON PARALLEL IN-VITRO AND IN-VTVO TESTS

Because of the unavailability of strictly comparable data, seven representative penicillins and the five cephalosporins currently used in Britain were evaluated in parallel, both in vitro and in vivo. Penicillin sensitive and resistant strains of Staphylococcus aureus and Proteus mirabilis were the main test organisms. Minimum bacteriocidal concentrations of cloxacillin, flucloxacillin, cephalothin, and cephazolin in serum were much higher than conventional minimum inhibitory concentrations in the absence of serum, Cephalexin and cephradine showed the smallest divergence in these values. Staph. aureus β-lactamase caused least damage to methicillin and cephradine, whereas enzymes from Escherichia, Klebsiella, and Bacillus cereus had least effect against cephradine followed by cephalexin. In mouse protection experiments, highly protein-bound antibiotics had relatively low efficacy Cephradine had the highest mean activity followed closely by cephaloridine and cephalexin. From the data cephradine was the cephalosporin of choice, and firm decisions were also made about the choice of penicillins.

Glucose-6-phosphate dehydrogenase in the population of Northern Thailand: evidence for two common electrophoretic variants with deficient enzyme activity.

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency, identified by a dye decolorization test, was found in 101 (12.5 percent) of 811 male subjects from northern Tailand. Blood samples from 169 subjects with normal G-6-PD activity and from all 101 subjects with G-6-PD deficiency were examined by electrophoresis on cellulose acetate gel with the following results: In all samples with normal G-6-PD activity the enzyme had the electrophoretic mobility of type B G-6-PD. 73 of the 101 G-6-PD deficient samples had the same mobility and are therefore probably identical with the common Mediterranean variant B-. 16 of the 101 deficient samples contained an electrophoretically fast G-6-PD, and 1 sample a ‘slow’ variant. In 11 deficient samples the enzyme could not be made visible. Kinetic studies on crude hemolysates suggest that the ‘fast’ variant has a higher mean activity and heat stability in comparison to the B- variant.