Repeated Measures General Linear Model Research Articles

The PTPN22 1858T Gene Variant in Type 1 Diabetes Is Associated With Reduced Residual β-Cell Function and Worse Metabolic Control

Evidence has been reported for a new susceptible locus for type 1 diabetes, the protein tyrosine phosphatase nonreceptor type 2 (PTPN22), which encodes a lymphoid-specific phosphatase. The aim of the study was to evaluate the influence of the C1858T variant of the PTPN22 gene on beta-cell function as measured by C-peptide levels from time of disease diagnosis through 12 months follow-up in a prospective series of 120 consecutive type 1 diabetic subjects. The C1858T polymorphism was genotyped using TaqMan. Fasting C-peptide, A1C, and insulin requirements were determined at diagnosis and every 3 months for 12 months; their change during follow-up was analyzed using the general linear model repeated-measures procedure. Fasting C-peptide levels were significantly lower and A1C levels were significantly higher in subjects carrying the PTPN22 1858T variant than in subjects homozygous for C1858 from time of disease diagnosis through 12 months of intensive insulin therapy follow-up (P = 0.008 and P = 0.01, respectively). These findings were independent of age at onset, sex, and HLA risk groups. The trend in C-peptide and A1C levels in the 12-month period did not differ significantly between subjects with or without the 1858T variant. Insulin dose was similar in the 1858T carriers and noncarriers. Type 1 diabetic subjects carrying the 1858T variant show significantly lower beta-cell function and worse metabolic control at diagnosis and throughout the study period than subjects homozygous for C1858; these differences remain unchanged over the course of the first year after diagnosis.

Statins Blunt HAART-Induced CD4 T-Cell Gains but Have No Long-Term Effect on Virologic Response to HAART

Statins are increasingly used in HIV-infected patients, but the effect of their immunomodulatory properties on antiretroviral-induced immune reconstitution is unknown. The authors compared 6-month and 1-year changes in CD4 T-cell count, plasma HIV ribonucleic acid (RNA), and serum lipids in 69 HIV-infected patients receiving statins and 127 controls matched by age, nadir CD4 T-cell count, and hepatitis C serostatus. All patients were receiving highly active antiretroviral therapy (HAART). The authors used standard statistical tests for univariate comparisons and estimated average change in outcome measurements through repeated measures general linear models. Patients receiving statins had significantly higher median CD4 T-cell counts (430 vs 225 cells/microL, P < .001) and lower HIV RNA levels (2.3 vs 2.9 log10 copies/mL, P < .001) than controls. Statin-treated patients had diminished CD4 T-cell gain at 6 months, but this difference was not statistically significant at 12 months, despite similar 12-month virologic success rates. Patients receiving statins gained, on average, an estimated 60 fewer CD4 T-cells in the first 6 months than controls. Exposure to statins was associated with decreased CD4 T-cell gains during HAART in a cohort of HIV-infected patients, despite adequate virologic response. Studies with longer follow-up and detailed metabolic and immunologic monitoring are needed to confirm these findings and assess their significance and mechanisms.

Litter fall and decomposition in primary, secondary and plantation forests in the Brazilian Amazon

Litter fall and leaf decomposition represent important functional processes, yet we have a limited understanding of these processes in disturbed and regenerating tropical habitats. Litter production, litterfall phenology and leaf decomposition were examined in primary forests, 14–19-year-old secondary forests and 4–5-year-old Eucalyptus urophylla plantations in the north-east Brazilian Amazon. Total annual litter fall was similar in primary and secondary forests, and lower in plantations. Leaf fall in primary and secondary forests was negatively associated with rainfall, and was highest in the dry season. Leaf fall in Eucalyptus plantations showed an opposite response, and peaked during the wet season. Decomposition experiments were carried out in the three habitats using 1200 litter bags (1 mm mesh) filled separately with leaves from four different species of tree, including an exotic plantation species ( E. urophylla) and trees typical of secondary ( Bellucia spp. and Vismia spp.) and primary forests ( Bertholettia excelsa). Litter bags were re-weighed at 3-month intervals 3, 6, 9 and 12 months after being placed on the forest floor. A repeated measures General Linear Model showed that litter decomposition was similar in the primary and secondary forest, and slowest in the Eucalyptus plantations. Leaves decomposed, from fastest to slowest, in the following order: E. urophylla > B. excelsa > Vismia spp. > Bellucia spp. There was no significant interaction between leaf species and habitat type. Our results indicate that secondary forests regenerating on abandoned and degraded Amazonian lands can be effective at restoring ecosystem processes such as litterfall and decomposition.

Affective Responses to Treadmill Running with Distraction and Stratified by Preference

Acute bouts of exercise have been associated with significant affective changes. Exercising with distractions may redirect an individual's attention away from feelings of fatigue and discomfort that are common during exercise. PURPOSE: The purpose of this study was to compare individuals' affective responses to exercise with video (VID), music (MUS) and no distraction (ND). METHODS: 25 individuals (16 females, 9 males; Mean age = 21.0 ± 1.5 years; Mean BMI = 24.0 ± 3.2) participated in this investigation. This study included 3, thirty-five min runs on a treadmill. One of the three conditions (VID, MUS, or ND) was randomly administered at each session. Each exercise session began with a 5 minute warm-up where the treadmill speed was increased until 80% of max heart rate (HR) was reached. The participants were then restricted to changing speed only at the completion of each subsequent 5 min stage. Affect was assessed using the Feeling Scale (FS) and the Felt-Arousal Scale (FAS). The FS and FAS were given prior to, every 5 min during, immediately following, and 10 min post exercise. In addition, participants were also asked to assess the distraction conditions and rank order them from most preferred to least preferred (most preferred: 14 MUS, 11 VID, 0 ND; moderately preferred: 11 MUS, 11 VID, 3 ND; least preferred: 0 MUS, 3 VID, 22 ND). Separate repeated measures general linear models were run for condition, as well as, preference. RESULTS: When stratified by distraction condition, analyses of the FS and FAS demonstrated a significant effect for time (p<.01). A significant condition effect was seen for FS (p=.02) with both VID and MUS being more pleasant than ND. When organized by preference, a significant time effect was also seen for FS (p<.001) and FAS (p=.01). A significant condition effect was also seen for FS (p=.03) with the most and moderately preferred conditions more pleasant than the least preferred condition. A time x preference condition interaction demonstrated a trend toward significance (p=.07). CONCLUSION: The use of distraction may be a desirable technique to employ when prescribing exercise. When doing so, it may be pertinent to allow the participant to select their own distraction. This strategy may have a positive influence on future exercise adherence.

Relationships between Self-Efficacy and Exercise Performance during Treadmill Running

Self-efficacy (SE) is the perception of one's ability to complete a specific course of action. It is believed that individuals high in SE are more likely to select more challenging tasks such as exercising at higher intensities. Research has also shown SE to be negatively related to ratings of perceived exertion (RPE) during exercise. PURPOSE: The purpose of this study was to identify relationships between SE and exercise intensity and RPE during bouts of exercise with video (VID), music (MUS) and no distraction (ND). METHODS: 25 individuals (16 females, 9 males; Mean age = 21.0 ± 1.5 years; Mean BMI = 24.0 ± 3.2) participated in this investigation. This study included 3, thirty-five min runs on a treadmill each with a randomly administered condition (VID, MUS, or ND). Each exercise session began with a 5 minute warm-up where the treadmill speed was increased until 80% of max heart rate (HR) was reached. The participants were then permitted to self-select treadmill speed at the completion of each subsequent 5 min stage. Self-efficacy was assessed prior to each exercise session. Exercise measures such as RPE, heart rate (HR), speed (MPH), and calories expended (CAL) were recorded every 5 min through out the exercise. One-tailed Pearson's correlations were done to assess the degree of relationship between self-efficacy and the exercise measures. RESULTS: Significant positive relationships were seen between SE and MPH (VID: r=.524, p=.004; MUS: r=.562, p=.002; ND: r=.679, p<.001), HR (VID: r=.354, p=.041; MUS: r=.372, p=.034; ND: r=.515, p=.004), and CAL (VID: r=.356, p=.040; MUS: r=.494, p=.006; ND: r=.400, p=.024) during all distraction conditions. During the ND condition SE was also significantly related to RPE (r=.514, p=.004). There were no significant relationships between SE and RPE for the other conditions (VID: r=.020, p=.462; MUS: r=.016, p=.469). A repeated measures general linear model revealed no condition effects for SE, MPH, HR, and CAL. CONCLUSIONS: These data confirm the belief that individuals with higher SE will select more challenging tasks as indicated by higher MPH, HR, and CAL. Interestingly, SE was positively related to RPE in the ND condition. This may be a result of self-selected rather than fixed intensity. These findings may also indicate that distraction may obfuscate the mediation of SE and RPE.

Near-infrared spectroscopy to define cognitive frontal lobe functions

Near-infrared spectroscopy (NIRS) monitors changes in the regional cerebral oxygenation (rSO 2 ) and has been used to study cerebral physiologic functions in normal states and during epileptic seizures. Yet, the limitations and pitfalls of the technique are not fully understood. The authors evaluated NIRS changes over the frontal lobes during language tasks known to be associated with the integrity of the dominant frontal lobe in 17 normal adults (handedness: 14 right, 3 left). Recording protocol involved a baseline (3 minutes) with the subject relaxed and thinking of a blue sky and a second baseline during voluntary mouth movements mimicking speech. Two standardized neuropsychological word-generation tasks (controlled word-association tests: CFL and Animals) were then administered (4 minutes total) followed again by the two baseline procedures. Mouth movement without verbalization increased rSO 2 values in excess of 2 SD of baseline fluctuations in 70% of the subjects. A t-test comparison of these baseline measurements was statistically significant (P < 0.0001). A general linear model repeated-measures procedure was then used to statistically examine NIRS increments during the cognitive tasks above and beyond the contribution produced by mouth movements during the second baseline. Compared to the second baseline, rSO 2 further increased significantly during the word generation tasks (left frontal F value = 21.4, P < 0.0001; right frontal F value = 15.2, P < 0.001), confirming the utility of the technique. There was no apparent difference related to handedness. These findings corroborate the usefulness of NIRS to demonstrate focal cerebral activation during an executive language task. However, interpretation of changes can be confounded by extracerebral factors such as mouth movement, a finding of particular relevance in NIRS clinical applications.

Prospective monitoring of lipid profiles in children receiving pravastatin preemptively after renal transplantation

Hyperlipidemia is common after renal transplantation (Tx) and contributes to the increased cardiovascular morbidity seen in the post-transplant period. Limited data are available on the utility of the statins in children after renal Tx. This 12-month prospective study was undertaken to determine the efficacy of pravastatin in reducing dyslipidemia after renal Tx in children and to determine predictors of dyslipidemia after Tx. From August 2001 to April 2004, all 17 newly transplanted pediatric renal transplant recipients at our center were preemptively treated with pravastatin from the immediate post-transplant period. Fasting lipid profiles were obtained at 1, 3, 6 and 12 months after Tx. Trends in the lipid profile were analyzed using the repeated measures general linear model (GLM). A historical cohort of pediatric renal-transplant recipients not treated with pravastatin was used as the control population. The mixed effects GLM was used for multivariable logistic regression analyses to determine the independent effect of age, pretransplant cholesterol (Chol), body mass index (BMI), creatinine clearance (CrCl), and corticosteroid and tacrolimus doses on the development of dyslipidemia. The mean age of the children at Tx was 8.7 yr. The GLM analysis showed that with time, there was a significant decline in the total Chol, serum triglyceride (TG), LDL and also HDL-Chol (p-value <0.05 for each). Compared with the controls, the mean serum Chol was lower at all time points post-transplant in the treated patients. However, despite treatment, the prevalence of hypercholesterolemia increased from 31% pretransplant to 53% at 1-month, but declined thereafter to 6% at 3 and 6 months and 0% at 1 yr. Multivariable regression analyses showed the prednisone dose, pretransplant Chol and age to be the most important risk factors for the development of dyslipidemia. No child developed complications related to therapy. In summary, pravastatin is safe in the post-transplant period in children and reduces serum Chol, LDL-Chol and TG. An unexpected finding in our study was the decline in HDL-Chol after Tx. Whether the preemptive use of the statins will result in lower cardiovascular morbidity, especially considering the concomitant reduction in HDL-Chol remains to be determined.

Women's personal and indoor exposures to PM2.5 in Mysore, India: Impact of domestic fuel usage

In traditional societies, women are more likely to be adversely affected by exposures to fine particulates from domestic fuel combustion due to their role in the family as the primary cooks. In this study, 24-h gravimetric personal and indoor PM2.5 exposures were measured for 15 women using kerosene and another 15 women using liquefied petroleum gas (LPG) as their main cooking fuel in Mysore, India. The women also answered a detailed questionnaire regarding their residential housing characteristics, health status, cooking practices and socioeconomic status. Repeated measurements were obtained during two seasons. The main objective of this study was to determine whether exposures to PM2.5 differed according to fuel usage patterns. A repeated-measures general linear model (GLM) was used to analyze the data. Women using kerosene as their primary cooking fuel had significantly higher exposures. During summer, the arithmetic mean ( standard error) for kerosene users personal exposure was 111 +/- 13 and 71 +/- 15 mu g m(-3) for LPG users. Kerosene users had higher exposures in winter (177 +/- 21 mu g m-3) compared to summer exposures. However, for LPG users there was no difference in their seasonal geometric mean exposures at 71 +/- 13 mu g m(-3). Indoor concentrations followed similar patterns. In summer, kerosene-using households had an arithmetic mean concentration of 98 +/- 9 mu g m(-3) and LPG-using households had an arithmetic mean concentration of 71 +/- 9 mu g m(-3). Winter concentrations were significantly higher than summer concentrations for kerosene users (155 +/- 13 mu g m(-3)) Again, LPG users showed only slightly higher indoor concentrations (73 +/- 6 mu g m(-3)) than kerosene users. Socioeconomic status, age, season and income were significant predictors of cooking fuel choice. (c) 2005 Elsevier Ltd. All rights reserved.

Acupuncture in haemodialysis patients at the Quchi (LI11) acupoint for refractory uraemic pruritus

Uraemic pruritus is a common problem in end-stage renal failure patients. Traditional therapies produce marginal or no results. Acupuncture has been reported to be effective. The aim of this randomized, controlled study was to validate a single acupoint for relieving uraemic pruritus. We randomized 40 patients with refractory uraemic pruritus into two groups. In group 1 (n = 20), acupuncture was applied unilaterally at the Quchi (LI11) acupoint thrice weekly for 1 month. In group 2 (controls, n = 20), acupuncture was applied at a non-acupoint 2 cm lateral to Quchi (LI11) thrice weekly for 1 month. Subjects responded to a pruritus score questionnaire given before and at the end of the 1 month treatment and at a 3 months follow-up. The results of the pruritus scores were analysed with the repeated measures general linear model to examine the effect of acupuncture on pruritus scores. In group 1, pruritus scores before and after acupuncture and at the 3 month follow-up were 38.3+/-4.3, 17.3+/-5.5 and 16.5+/-4.9, and in group 2 (controls) they were 38.3+/-4.3, 37.5+/-3.2 and 37.1+/-5, respectively. Laboratory tests showed no significant differences between the two groups. Pruritus scores were significantly lower after acupuncture and at the 3 month follow-up, P<0.001. Acupuncture at the Quchi (LI11) acupoint is an easy, safe and effective means of relieving uraemic pruritus.

The Effect of Solar-Simulated Radiation on the Elicitation Phase of Contact Hypersensitivity does not Differ Between Controls and Patients with Polymorphic Light Eruption

It has been suggested that polymorphic light eruption (PLE) is characterized by a failure of ultraviolet radiation (UVR)-induced immunosuppression, resulting in a type-IV hypersensitivity response to photoinduced antigens. We measured the effect of solar-simulated radiation (SSR) on the elicitation phase of contact hypersensitivity to 2,4-dinitrochlorobenzene (DNCB), in ten PLE patients and 11 controls. Subjects were given a sensitizing dose of DNCB, and 3 wk later were exposed to 0.75 and 2 minimum erythema doses (MED) of SSR on the upper inner arm. Immediately and 24 h later these sites, and a non-irradiated control site, were challenged with DNCB. The resulting increase in skin thickness was measured with high-frequency ultrasound. Overall, 2 MED caused 17%-20% suppression of elicitation responses (compared with 93% suppression of sensitization reported previously), but the effect of SSR varied greatly between subjects, with some subjects showing potentiated responses, which may be of relevance to false-positive reactions in photopatch testing. In a repeated measures general linear model, SSR overall caused significant suppression of responses (p<0.001); there was less suppression in older subjects (p=0.009) but there was no significant difference between PLE patients and age-matched normal controls. These results contrast with our previous finding of a resistance to UVR-induced suppression of sensitization to DNCB in PLE. This difference may reflect the greater importance of Langerhans cells in the sensitization phase, and is consistent with the hypothesis that PLE arises from impaired suppression of Langerhans cell activation or migration.

Determination of arterial compliance using blood pressure waveform analysis with the CR-2000 system: Reliability, repeatability, and establishment of normal values for healthy European population—the seven European sites study (SESS)

We determined the reliability and repeatability of measurements of arterial compliance (AC) and gender- and age-specific normal ranges for a healthy European population. Three hundred eight healthy volunteers from seven sites were evaluated. Two measurements were taken during the first visit, repeated on a second visit 1 to 4 weeks later. We used the HDI/PulseWave CR-2000 for measurements of AC. Intravisit measurements, taken 5 min apart, differed by less than 3% (range, 0.36% to 2.97%). All intervisit measures differed by less than 4% (range, 0.24% to 3.67%); none of these differences was statistically significant. All correlation coefficients for pairs of AC parameters measured 5 min apart at the same visit were significant at P < .0001. Paired AC parameters at visit 1 and 2 were highly correlated (P < .0001). Repeated measures GLM (general linear model) failed to detect a significant association between either of the AC parameters and visit (first or second), time (first or second measure at the same visit), and visit-by-time (the interaction of the two preceding factors), suggesting that order of measure had no effect on the final value. Analysis of reliability was used to develop a strictly parallel model estimate of unbiased reliability. Both intravisit and intervisit estimates of reliability indicate good repeatability of measure and were significant (P < .0001). The AC values were found to differ significantly by age group, with an inverse association between each of the AC parameters and age group. Measurement of the arterial waveform with the CR-2000 system is highly reproducible in healthy subjects.

Investigation of Pediatric Renal Transplant Recipients with Heavy Proteinuria after Sirolimus Rescue

Little is known about the incidence and evolution of proteinuria as a complication of sirolimus rescue in children. This study describes pediatric renal transplant (Tx) recipients who were treated with sirolimus and who developed heavy proteinuria. Risk factors for the development of proteinuria and its time course are explored. Data at various time points after sirolimus introduction were abstracted from the records of children treated at the author's center. The repeated measures general linear model and the Student's paired t test were used to analyze changes in laboratory values over time. Of the 13 children on sirolimus, 12 developed heavy proteinuria after a mean interval of 1 month. The mean urine protein (Up)-to-creatinine (c) ratio increased from 1.1 to a peak value of 3.9 (P=0.003) at 4.6 months after the start of sirolimus. Although not statistically significant, children on no calcineurin inhibitor (CNI) had a greater increase in the Up/c than those on low-dose CNI. At last follow-up, with the use of angiotensin receptor blockers (ARB), the Up/c declined to 2.2. No predictors could be identified for the development of proteinuria. Heavy proteinuria is common after the use of sirolimus as rescue therapy in children with renal Tx. Whether this is attributable to a toxic effect of the sirolimus itself or to lower CNI exposure is uncertain. Early detection of proteinuria is important to enable prompt intervention. Most children have a reduction in their Up/c with the use of ARB and can therefore be continued on sirolimus.

Stability of oral health-related behaviour in a Norwegian cohort between the ages of 15 and 23 years.

To assess the stability in self-reported oral health behaviour in a Norwegian cohort between the ages of 15 and 23 years. Self-administered questionnaires were used as part of a longitudinal cohort study. In 1992, a representative sample of 963 15-year-old adolescents participated, of which 676 (70%) and 567 (58%) remained in the study at ages 18 and 23 years. A total of 389 (40% of baseline) participated at each data collection, i.e. at ages 15, 18, 19, 21 and 23 years. General linear model (GLM) repeated-measures anova revealed statistically significant main effect of time with respect to soft drink and sweet consumption (F = 22.4, P < 0.001 and F = 4.3, P < 0.05, respectively). Adjusted mean scale scores of soft drink intake increased from 2.3 at age 15 years to 3.4 at age 23 years. The corresponding figures for consumption of sweets were 2.6 and 2.8. Two-way interactions achieved statistical significance with gender for soft drink consumption and toothbrushing. GLM repeated-measures with each gender revealed that soft drink consumption increased with time more extensively in boys (from 2.9 to 4.2, F = 13.5, P < 0.001) than in girls (from 1.9 to 2.6, F = 8.1, P < 0.001). Tracking or maintenance across time of the relative ranking at age 15 years occurred with all the four behaviours investigated. A total of 68-92% remained active and inactive regarding soft drink and sweet consumption, flossing and toothbrushing. The results provide evidence of tracking and early consolidation of oral health behaviour. This adds support for the assumption given for early intervention to prevent oral diseases.

The availability of psychiatric programs in private substance abuse treatment centers, 1995 to 2001.

The high rate of co-occurrence of substance abuse and mental disorders renders the availability of psychiatric programs, or integrated service delivery, a vital quality-of-care issue for substance abuse clients. This article describes the availability of psychiatric programs and integrated care for clients with severe mental illness in the private substance abuse treatment sector and examines these patterns of service delivery by profit status and hospital status. S: Survey data from the National Treatment Center Study, which is based on a nationally representative sample of privately funded substance abuse treatment centers, were used to identify the proportion of centers that offered psychiatric programs in 1995-1996, 1997-1998, and 2000-2001. Centers reported whether they treated clients with severe mental illness on-site or referred them to external providers. Repeated-measures general linear models were used to test for significant changes over time and to assess mean differences in service availability by profit status and hospital status. About 59 percent of private centers offered a psychiatric program, and this proportion did not significantly change over time. The proportion of centers that referred clients with severe mental illness to external providers increased significantly from 57 percent to 67 percent. For-profit centers and hospital-based centers were significantly more likely to offer psychiatric programs and were less likely to refer severe cases to other providers. S: Although the importance of integrated care for clients with dual diagnoses is widely accepted, data from the private substance abuse treatment sector suggest that this pattern of service delivery is becoming less available.

A behavioral comparison of New Zealand White rabbits ( Oryctolagus cuniculus) housed individually or in pairs in conventional laboratory cages

Despite their gregarious nature, rabbits used for research are often housed individually due to concerns about aggression and disease transmission. However, conventional laboratory cages restrict movement, and rabbits housed singly in these cages often perform abnormal behaviors, an indication of compromised welfare. Pairing rabbits in double-sized cages could potentially improve welfare by providing both increased space and social stimulation. We compared the behavior of female New Zealand White rabbits ( Oryctolagus cuniculus) housed either individually ( N=4) in cages measuring 61 cm×76 cm×41 cm or in non-littermate pairs (four pairs) in double-wide cages measuring 122 cm×76 cm×41 cm. The rabbits were kept under a reversed photoperiod (lights on 22:00–12:00 h). Each rabbit was observed five times per week for 5 months, using 15-min focal animal samples taken between 08:00–09:00, 12:00–13:00, and 16:00–17:00 h. Data were analyzed using a repeated measures General Linear Model (GLM). Over the 5 months, individually housed rabbits showed an increase in the proportion of the total behavioral time budget spent engaged in abnormal behaviors (digging, floor chewing, bar biting), from 0.25 to 1.77%, while pairs remained unchanged at 0.95% (treatment×time interaction, F 1,24=4.60; P≤0.0422). Paired rabbits engaged in more locomotor behavior ( F 1,6=16.49; P≤0.0066) than individual rabbits (average proportions of time budget: 2.71 and 0.70% for paired and individual rabbits, respectively), which may be important because caged rabbits are susceptible to osteoporosis and other bone abnormalities due to the restricted ability to move. Time spent feeding and body weights of dominant and subordinate rabbits in a pair did not differ, indicating that food competition was not a problem, and paired rabbits were often observed in physical contact (26.7% of data records) although the size of the cages allowed physical separation. Aggression between pairmates did not increase significantly during the study. However, one pair did have to be separated at the end of the study due to bite wounds from persistent aggression. Thus, although methods for decreasing injurious aggression require further investigation, the beneficial effects of pair housing in decreasing abnormal behaviors and increasing locomotion suggest that pair housing should be considered as an alternative to individual housing for caged laboratory rabbits.

Comparisons of vegetarian and beef-containing diets on hematological indexes and iron stores during a period of resistive training in older men

Objective To test the hypothesis that older men who consumed a vegetarian (lacto-ovo) diet would develop a lower iron status compared with older men who consumed a beef-containing diet during a period of resistive training (RT). Design Experimental, repeated measures study. Subjects Twenty-one healthy men aged 59 to 78 years, with a BMI range of 24 to 33 kg/m2, completed the study. Intervention All men consumed a vegetarian diet for 2 weeks (baseline). After this, the men were randomly assigned to one of two dietary groups. Eleven men consumed a beef-containing diet, and 10 men continued to consume a vegetarian diet for 12 weeks. During this time all subjects participated in RT three days per week, designated as RT1 to RT12. Main outcome measures Serum ferritin and serum iron concentrations, transferrin saturation, transferrin receptor, total iron binding capacity, and selected hematological variables, as well as selected nutrient intakes and estimated iron bioavailability from three-day diet records, were determined at baseline, RT5, and RT12. Statistical analyses A general linear model repeated-measures ANOVA was used to examine the effects of group, time, and group×time interactions for iron status and dietary data. Results Total iron intake was not different between the two groups; however, the beef group had a three to four times greater intake of bioavailable iron (P<.01) than the vegetarian group. Serum iron, total iron binding capacity, transferrin saturation, and transferrin receptor were not significantly different between the beef and vegetarian groups, or changed over time with RT. Serum ferritin decreased over time in both the beef and vegetarian groups during RT (P<.01). Re-introduction of beef into the diets of the beef group increased hemoglobin concentration and hematocrit compared with the vegetarian group during the 12 weeks of RT (group×time, P<.05). These changes were within clinically normal limits. Applications/Conclusions Older men who consume a beef-containing, higher-bioavailable-iron diet, compared with a vegetarian, lower-bioavailable-iron diet, have an increased hematological profile during a 12-week period of RT. Older men who consume either a beef-containing or a vegetarian diet maintain a hematological profile within clinically normal limits during 12 weeks of RT. J Am Diet Assoc. 2003;103:594-601.

Rabbits fed on β-carotene have higher serum levels of all-transretinoic acid than those receiving no β-carotene

The aim of the present work was to determine the effect of giving increasing doses of supplements of beta-carotene on serum retinoic acid levels in rabbits. Four groups of 7-week-old female rabbits were fed for 9 weeks on a pelleted diet containing 1.72 mg vitamin A as retinyl acetate/kg and including control gelatin beadlets devoid of beta-carotene or 1, 2 or 4 mg beta-carotene/kg body-weight per d. Serum was collected at 3, 6 and 9 weeks after the beginning of the experiment and the concentration of all-trans retinoic acid was determined by a gradient reverse-phase high-performance liquid chromatography system following a double-phase extraction. The average concentration of retinoic acid in serum of the combined control and 1 mg beta-carotene/kg groups was 3.80, 3.06 and 2.40 nM at 3, 6 and 9 weeks respectively. The concentrations of retinoic acid in serum of the combined 2 and 4 mg beta-carotene/kg groups were 4.80 nM (P less than 0.05), 3.76 nM (not significant) and 4.90 nM (P less than 0.005) at 3, 6 and 9 weeks respectively. A SAS (SAS Institute Inc., 1985) general linear model repeated-measures analysis of variance revealed that the effects of treatment (P less than 0.01), time (P less than 0.05) and treatment x time interaction (P less than 0.05) were statistically significant. It is concluded that giving beta-carotene is associated with higher concentrations of all-trans retinoic acid in the serum of rabbits than in those receiving no beta-carotene.