Step-counting accuracy of activity monitors in persons with Down syndrome.

BACKGROUND: Accelerometers and pedometers have been used to monitor the number of steps. However, the evidence on the step-counting accuracy of these devices - especially accelerometers - is limited in persons with Down syndrome (DS). This study therefore examined the accuracy of accelerometers placed on the hip or wrist and of a pedometer with a uni-axial accelerometer mechanism in measuring steps in persons with DS and whether device error is associated with walking speed, height, weight, body mass index, waist circumference, leg length, age or sex. METHOD: Seventeen persons with DS (eight women and nine men; age 33 ± 15 years) walked over-ground for 6 min at their preferred speed. The steps were measured with a hip-worn and a wrist-worn ActiGraph accelerometer using the manufacturer's default (DF) and low-frequency extension (LFE) filters, and with the NL-1000 New Lifestyles pedometer on the hip. Steps were also measured with hand tally which served as the criterion. RESULTS: Absolute percent error was considerable and differed statistically between devices (P = 0.001); however, error improved for accelerometers when LFE was applied (Hip-DF: 31.6 ± 18.8%; Hip-LFE: 9.7 ± 12.8%; Wrist-DF: 32.7 ± 14.2%; Wrist-LFE: 13.6 ± 10.2%; Pedometer: 23.2 ± 22.8%). Bland-Altman plots indicated underestimation of steps for accelerometers and the pedometer. Application of LFE, however, improved the prediction of the accelerometers. The number of steps measured by the hip accelerometer with LFE and by the pedometer did not differ statistically from actual steps. Steps by the remaining methods were significantly lower than hand tally (P ≤ 0.001). Correlations between percent error for each device and walking speed, anthropometry, age or sex ranged between -0.28 and +0.48, and were non-significant, except for age. CONCLUSIONS: The results demonstrated that the pedometer and ActiGraph accelerometers have considerable error in measuring steps of persons with DS. Application of LFE, however, significantly improved the step-counting performance of the Actigraph accelerometers.

The effect of physical activity and fitness on specific antibody production in college students.

BACKGROUND: The purpose of this study was to determine the effect of moderate physical activity/fitness on the immune response to a defined antigen, in particular, the hemagglutinin-inhibition response to the H1 (A/Texas/36/91) and H3 (A/Johannesburg/33/94) components of the 1995-96 Influenza virus vaccine. METHODS: Sixty-seven volunteers 18-30 years of age (mean 21.1 + 2.3) participated in the study. Physical activity was assessed using the Stanford 7-Day Recall Questionnaire, physical fitness (VO2max) was predicted based on graded submaximal cycle ergometry. Participants were divided into six groups (lower-active/fit, moderate active/fit, and higher active/fit), based on their scores on the 7-Day Recall Questionnaire or predicted VO2max, respectively. Plasma samples were collected prior to, one, two, four, and six weeks post vaccination. A total of four separate repeated measures ANOVA were utilized to evaluate the effect of physical fitness and physical activity on the immune response to the H1 and H3 components of the vaccine. RESULTS: As expected, for both antigens, titers significantly increased after vaccination, with the highest titers found on week four (H1) and week six (H3), respectively. However, for both antigens, there was no difference between groups and no significant interaction. CONCLUSIONS: The results of this study showed no significant effect of physical fitness or physical activity on the production of specific antibody in the range of physical fitness and physical activity found within this group of college students.

Lactate production in response to maximal and submaximal StairMaster PT4000 and treadmill exercise.

BACKGROUND: The purpose of this study was to measure the amount of lactate produced, as an indication of fatigue, in response to maximal and submaximal stairstepper (SM) and treadmill (TM) exercise. METHODS: Thirty volunteers (15 males, mean age 23 yrs; 15 females, mean age 22 yrs) completed maximal and submaximal SM and TM protocols on four separate visits to the laboratory to determine maximal oxygen consumption (VO2max), and blood lactate concentrations. Maximal TM testing consisted of the Bruce protocol, while the maximal SM protocol involved progressing in increments of 2 levels every 2 minutes. Eight minutes of submaximal TM and SM exercise was performed at an intensity of 65% of VO2max, as measured during maximal TM and SM testing. Fifty microliters of blood was collected via fingerprick of the index finger prior to, and immediately post maximal and submaximal TM and SM exercise, and during minutes 3, 5, and 7 of active recovery. Red blood cells were lysed and analyzed immediately using the YSI # 1500 Sport lactate analyzer. RESULTS: TM-VO2max, was significantly higher for both, males and females, compared to SM-VO2max. Repeated measured analyses of variance revealed significantly higher blood lactate levels during the same relative submaximal workloads for SM compared to TM exercise. CONCLUSIONS: These findings suggest that an increased lactate production during submaximal SM exercise may result in early fatigue and, thereby, limit maximal performance on the SM.

Perception of body shape in elderly white and black men.

In assessing the effects of age, physical activity and ethnic identity on perception of body shape in a group of 110 elderly men, the difference was significant for perception of current and ideal body shape, with the greatest difference for the 49 physically active black elderly men.

Viewing music videotapes during exercise and ratings of perceived exertion.

30 men 18 to 25 years of age participated in two treatments presented in counterbalanced order. They exercised for 6 min. on a Monarch cycle ergometer at a workload of 122.5 W while viewing and listening to music videotapes or exercised in a quiet environment. External stimuli in the viewing and listening to music videotapes did not distract subjects from assessing their exertion during exercise.

Effect of viewing the RPE scale on the ability to make ratings of perceived exertion.

7 subjects exercised while viewing and not viewing the Rating of Perceived Exertion scale during exercise to assess whether ratings of perceived exertion are influenced by viewing the scale itself. Analysis suggested that monitoring moderate to high intensity exercise without viewing the RPE scale may result in an underestimation of exertion.

Role of alpha v beta 5 and alpha v beta 6 integrin glycosylation in the adhesion of a colonic adenocarcinoma cell line (HT29-D4).

We have previously characterized the expression of the alpha nu beta 5 and alpha nu beta 6 integrins as major receptors for the human colonic adenocarcinoma cell line (HT29-D4), on vitronectin and fibronectin, respectively [Lehmann et al. (1994): Cancer Res 54:2102-2107]. In the present work we investigated the glycosylation role of these integrins in their adhesive functions. To this end, we used glycohydrolases to show that cell surface integrins were N-glycosylated and sialylated, and that only the alpha v subunit carried some immature oligosaccharide side chains. To alter the glycosylation state of the cell surface alpha v beta 5 and alpha v beta 6 integrins, we used two oligosaccharide-processing inhibitors: 1-deoxymannojirimycin (dMNJ) and tunicamycin (TM). Following treatment of HT29-D4 cells with dMNJ, cell surface alpha v beta 5 and alpha v beta 6 carried only high-mannose-type sugar chains, while TM-treated cells expressed de-N-glycosylated integrins. Neither alpha/beta heterodimers assembly nor cell surface expression were impaired in the presence of the drugs. Finally, we established that adhesion of dMNJ- or TM-treated cells was altered on both vitronectin and fibronectin substrata, whereas the adhesion of these cells on laminin or collagen type I was virtually unchanged.

Structural and functional analysis of the human vasoactive intestinal peptide receptor glycosylation. Alteration of receptor function by wheat germ agglutinin.

The vasoactive intestinal peptide (VIP) receptor from the human melanoma cell line IGR39 has been shown to be a 60-kDa glycoprotein. Using serial lectin affinity chromatography, as well as specific glycosidases, we demonstrate that VIP receptor-linked carbohydrates are predominantly tri- or tetraantennary sialylated N-linked oligosaccharides, 27% of which are fucosylated, and some may have terminal galactose residues. Treatment of 125I-VIP receptor complexes with peptide-N4-(N-acetyl-beta-D-glucosaminyl)asparagine amidase revealed the presence of at least three N-linked carbohydrate chains/receptor polypeptide. To investigate the functional role of the carbohydrate moiety, 125I-VIP binding to IGR39 cell membranes was tested in the presence of soluble lectins. Among the lectins tested, only wheat germ agglutinin (WGA) was found to markedly inhibit VIP binding in a dose-dependent manner. Binding data indicated that the presence of the lectin led to a 3-fold increase in Kd value, from 0.15 to 0.44 nM, without any change in the number of available binding sites. The potent inhibitor of WGA binding, N,N',N"-triacetylchitotriose, completely reversed the effect of the lectin. On the other hand, VIP binding inhibition persisted even after neuraminidase treatment, suggesting that sialic acids were not directly involved. Furthermore, WGA inhibition was not abolished although most, if not all, VIP receptor oligosaccharides were converted to high mannose type structures by treating IGR39 cells with deoxymannojirimycin. Finally, whereas the pharmacological profile of VIP receptor was virtually identical, the presence of WGA greatly reduced the VIP-stimulated cAMP in IGR39 cells, indicating that the lectin alters the ability of the receptor to interact with the adenylate cyclase system.

Posterior rotator cuff strengthening using theraband(r) in a functional diagonal pattern in collegiate baseball pitchers.

The deceleration phase of the pitching mechanism requires forceful eccentric contraction of the posterior rotator cuff. Because traditional isotonic strengthening may not be specific to this eccentric pattern, a more effective and functional means of strengthening the posterior rotator cuff is needed. Twelve collegiate baseball pitchers performed a moderate intensity isotonic dumbbell strengthening routine for 6 weeks. Six of the 12 subjects were randomly assigned to an experimental group and placed on a Theraband(R) Elastic Band strengthening routine in a functional-diagonal pattern to emphasize the eccentric contraction of the posterior rotator cuff, in addition to the isotonic routine. The control group (n = 6) performed only the isotonic exercises. Both groups were evaluated on a KIN-COM(R) isokinetic dynamometer in a functional diagonal pattern. Pretest and posttest average eccentric force production of the posterior rotator cuff was compared at two speeds, 60 and 180 degrees /s. Data were analyzed with an analysis of covariance at the .05 level with significance at 60 degrees /s. Values at 180 degrees /s, however, were not significant. Eccentric force production at 60 degrees /s increased more during training in the experimental group (+19.8%) than in the control group (-1.6%). There was no difference in the two groups at 180 degrees /s; both decreased (8 to 15%). Theraband was effective at 60 degrees /s in functional eccentric strengthening of the posterior rotator cuff in the pitching shoulder.

Retinal damage thresholds from single-pulse laser exposures in the visible spectrum.

The risks of using lasers, particularly ocular hazards, have called for the definition of exposure limits. Our investigations involved the retinal effects of the laser beam in the visible spectrum and were directed toward verifying the limit values by defining the thresholds of retinal damage in experiments carried out on the rabbit and the monkey. The wavelengths emitted by the experimental set-ups were 593 and 532 nm, the pulse durations were 600 and 40 ns, and the retinal image diameter varied from approximately 30 to 570 microns. A direct ophthalmoscopic observation and a method using fluorescein angiography were employed to detect a pathologic change in the retina. The energy correlates of retinal lesions were statistically analyzed by a method of probit analysis. The results showed that determining funduscopic thresholds is chiefly a function of the investigation technique used and the delay in observation after the exposure. Our results obtained with fluorescein angiography extrapolated to the human eye support the exposure limit established for intrabeam viewing, but not for an extended source laser which corresponds to a probability of damage increasing with the retinal image diameter. The exposure limit related to the experimental retinal spot size of 285 and 570 microns corresponds to damage probabilities of 7% and 32%, respectively.

Hair mineral analysis: biochemical imbalances and violent criminal behavior.

Trace mineral analysis of human hair was utilized to determine whether violent and nonviolent criminals could be differentiated on the basis of concentrations of levels of major and trace minerals. 40 violent and 40 nonviolent inmates from a prison population were selected for study. 27 mineral levels were analyzed and a discriminant function analysis correctly classified 86% of the violent and 78% of the nonviolent inmates. The results lent support to the hypothesis that significantly different levels of trace minerals could be found between the two groups.

Construction and validation of a perceived physical fitness scale.

Numerous researchers have demonstrated that improvements in physical conditioning can influence one's psychological functioning. Heaps proposed in 1978 that physical improvement does not improve psychological functioning. Heaps contended that only when an individual is cognitively aware of the physical improvement can one expect psychological functioning to be enhanced through physical activity. The purpose of this study was to construct a valid and reliable instrument to assess an individual's perception of his physical fitness.

Relating trait anxiety to perceived physical fitness.

This study was designed to determine the relation of actual cardiovascular physical fitness and perceived physical fitness to trait anxiety. 32 older adult (M age = 68.19 yr.) subjects completed a voluntary maximal graded exercise stress test on a motor driven treadmill to determine their actual cardiovascular physical fitness. Subjects also completed Abadie's Perceived Physical Fitness Scale along with Spielberger's Trait Anxiety Inventory. The partial correlation between actual cardiovascular physical fitness and trait anxiety with the influence of perceived physical fitness removed indicated a nonsignificant relation. The partial correlation between perceived physical fitness and trait anxiety with the influence of actual cardiovascular physical fitness removed indicated a significant inverse relation. Present results suggest that trait anxiety is correlated better with an individual's self-perception of his physical fitness than the actual cardiovascular physical fitness.

Growth in serum-free medium of human colonic adenocarcinoma cell lines on microcarriers: a two-step method allowing optimal cell spreading and growth.

Human colonic adenocarcinoma cells have been successfully grown on polystyrene microcarriers by modifying the culture conditions used in monolayer culture. The method can be divided into two culture phases: a) a phase of spreading, wherein cells were seeded in presence of serum-supplemented medium; b) a phase of active growth wherein spread cells on the beads were allowed to grow in a serum-free medium. Under these conditions, optimal spreading and growth of HT 29 and HRT 18 cells on the microcarriers were obtained. A differential propagation was observed between HT 29-D4 and HT 29-D9 cells (both clonal populations derived from HT 29 cells) on the microcarriers that is tentatively related to the discrepancy observed in the spreading efficiency of these clonal cells on serum-coated culture flasks. An index of spreading efficiency (IS index) has been defined to quantify the efficiency of spreading of each cell line on microcarriers. These data gave the opportunity to develop serum-free, scale-up methods to culture cells like HT 29 which release potentially useful products.

Evidence for an ectophosvitin kinase activity that phosphorylates a 123 kDa endogenous substrate on a human colonic adenocarcinoma cell (HT 29).

When HT 29 cells grown as a monolayer were incubated in a synthetic medium in presence of 0.1 microM [gamma 32P]-ATP, the radioactivity was incorporated predominantly into three major endogenous polypeptides of 123 kDa, 50 kDa and 46 kDa. The radioactive proteins could be detected as soon as 30 s after the addition of the labelled ATP. When exogenous substrates such as casein or phosvitin were added in the synthetic medium, these proteins became phosphorylated. The phosvitin-kinase activity was released in the culture medium following an incubation of the cells with phosvitin. Depletion of the enzymatic activity from the cell surface as well as competition between phosvitin and endogenous substrates led specifically to the inhibition of the 123 kDa polypeptide phosphorylation. At low density, endogenous phosphorylation increased with the cell number, whereas on the contrary it decreased at high cell density. We concluded that the surface of HT 29 cells expressed several protein kinase activities. We have characterized one of them as an ectophosvitin kinase which phosphorylated specifically a 123 kDa polypeptide and whose expression or accessibility varied according to cell density.

Spontaneous and induced dome formation by two clonal cell populations derived from a human adenocarcinoma cell line, HT29.

The replacement of glucose by galactose in the culture medium resulted in partial structural and functional enterocytic differentiation of HT29 cells. In order to characterize populations of homogeneously differentiated HT29 cells we have selected two clonal cell lines HT29-D4 and HT29-D9 with the following functional and structural characteristics when grown in a galactose-containing medium: the two clonal cell populations were permanently morphologically differentiated as shown by the presence of mature junctional complexes and a well-organized brush border (especially for HT29-D4 cells); HT29-D4 and HT29-D9 cells were able to form domes early in confluency, which indicated a functional state of differentiation; the process of differentiation was fully reversible when glucose was added to the culture medium. The induction of domes was investigated in these two cell populations and we demonstrated for the first time that proteolytic enzymes are potent inducers of dome formation. The architecture of domes either obtained spontaneously or induced by proteolytic enzymes was not maintained in the presence of ouabain (a specific inhibitor of the Na+/K+-ATPase). In conclusion, HT29-D4 and HT29-D9 cells can be maintained permanently in a differentiated state in a glucose-free medium and were able to form domes at confluency. The observation that proteolytic enzymes were able to induce dome formation can help in the comprehension of the mechanism involved in the establishment of the differentiated state.

Cycle of the vasoactive intestinal peptide and its binding site in a human adenocarcinoma cell line (HT 29).

The disappearance of vasoactive-intestinal-peptide (VIP) binding sites at the cell surface of a cultured target cell, originating from a human colonic adenocarcinoma (HT 29 cell line), was studied, after preexposition of the cell to the peptide, as a function of time, VIP concentration and temperature. Maximum effect (60-80% loss of binding capacity) was obtained after a 5-10 min exposure of the cells at 37 degrees C with a VIP concentration of 100 nM. The t1/2 of maximum disappearance was less than 2 min and the concentration of native VIP giving half-maximum decrease in 125I-VIP binding was 6 nM. The affinity of remaining binding sites for VIP was not affected compared to that of control cells (Kd = 0.3 nM). Disappearance of VIP binding sites was specific since, with the same conditions of preincubation, the specific binding of 125I-labeled epidermal growth factor to HT 29 cells was not modified. The phenomenon was reversible and 90% of binding capacity could be restored in less than 60 min by incubating cells in VIP-free medium. Correlatively we showed, by two independent experimental procedures, that 125I-VIP, initially bound to HT 29 cells, was maximally internalized after 10 min of incubation at 37 degrees C. All the data strongly suggest that: internalization of VIP is receptor-mediated; upon exposure to native VIP, VIP receptors are down-regulated or at least sequestered within HT 29 cells.

Complete amino acid sequence and location of the five disulfide bridges in porcine pancreatic alpha-amylase.

Porcine pancreatic alpha-amylase (1,4-alpha-D-glucan glucanohydrolase EC 3.2.1.1), a single polypeptide chain, contains nine residues of methionine. Eight different fragments resulting from cleavage of this molecule by cyanogen bromide were characterized. The sequences of six of them have previously been reported. Two missing fragments, CN2 (82 residues) and CN3b1 (76 residues) were purified after breaking of the interpeptidic disulfide bridge and their complete sequence as well as that of the previously purified CN1 peptide (102 residues) are reported here. The location of the three disulfide bridges present in these peptides was determined. Ordering of the carboxymethylated cyanogen bromide fragments was carried out by pulse labeling the amylase chain in vivo. The complete sequence of the porcine pancreatic amylase chain (496 residues) and the location of its five disulfide bridges is presented. Comparison with human and mouse pancreatic and salivary alpha-amylases and with rat pancreatic amylase obtained from the corresponding cDNA nucleotidic sequences shows a high degree of homology between mammalian alpha-amylases.

Characterization of the vasoactive intestinal peptide (VIP) binding sites: a biochemical and an immunological approach.

The initial event of VIP action is its interaction with a specific receptor at the surface of a target cell. The understanding of the fine mechanism of action of VIP requires the characterization and of course the purification of the receptor. The understanding of the mechanism which regulates the number of receptor sites at the cell surface, if it occurs, is also a way to characterize the properties of VIP receptor. In this paper we report a number of data which represent several attempts to characterize VIP receptor in a human colonic adenocarcinoma cell (HT 29 cells). We have characterized a monoclonal antibody which partially inhibits 125I-VIP binding to HT 29 cells. We have specifically cross-linked, on intact HT 29 cells, a major polypeptide of Mr-64,000 with 125I-VIP using DTSP or DSS as cross-linking reagents. This polypeptide behaves like a high affinity binding site for VIP. We have demonstrated that VIP is rapidly internalized in HT 29 cells (in less than 10 minutes) and that simultaneously VIP receptors were no more detectable on the cell surface by cross-linking experiments. This suggests that VIP is internalized together with its receptor.