Use of remote monitoring with continuous glucose monitoring in young children with Type 1 diabetes: the parents' perspective

AIM

Remote monitoring with continuous glucose monitoring (CGM) in children with Type 1 diabetes mellitus has recently become available, but little is known about caregivers' experiences of its use, particularly in younger children. The aim of this study was to explore parents' everyday experiences of using this technology.

METHODS

The parents of children with Type 1 diabetes diagnosed for > 1 year, aged 2-12 years were invited to participate in a semi-structured interview. Interviews were the second phase of a randomized cross-over study using standard insulin therapy with or without CGM and remote monitoring for two 3-month periods. Open-ended questions were used to explore parents' real-life experiences of the remote monitoring and CGM system. Interviews were analysed using thematic analysis.

RESULTS

Five themes related to remote monitoring emerged: (i) impact on sleep quality for the parents, (ii) peace of mind, (iii) impact on anxiety, (iv) freedom and confidence for the parents and children, and (v) impact on relationships. Furthermore, parents reported on themes related to CGM in general, such as better understanding of how to manage and control their child's diabetes and experiences related to physical or technical aspects.

CONCLUSION

Overall, parents of primary school children reported that using remote monitoring and CGM was a mostly beneficial experience. However, negative aspects within the themes were also reported. These findings will help to provide a structure to discuss parent and child expectations and provide targeted education at the start of using remote monitoring and CGM.

Safety and efficacy of the predictive low glucose management system in the prevention of hypoglycaemia: protocol for randomised controlled home trial to evaluate the Suspend before low function

INTRODUCTION

Innovations with sensor-augmented pump therapy (SAPT) to reduce hypoglycaemia in patients with type 1 diabetes are an ongoing area of research. The predictive low glucose management (PLGM) system incorporates continuous glucose sensor data into an algorithm and suspends basal insulin before the occurrence of hypoglycaemia. The system was evaluated in in-clinic studies, and has informed the parameters of a larger home trial to study its efficacy and safety in real life.

METHODS AND ANALYSIS

The aim of this report is to describe the study design and outcome measures for the trial. This is a 6-month, multicentre, randomised controlled home trial to test the PLGM system in children and adolescents with type 1 diabetes. The system is available in the Medtronic MiniMed 640G pump as the 'Suspend before low' feature. Following a run-in period, participants are randomised to either the control arm with SAPT alone or the intervention arm with SAPT and Suspend before low. The primary aim of this study is to evaluate the time spent hypoglycaemic (sensor glucose <3.5 mmol/L) with and without the system. The secondary aims are to determine the number of hypoglycaemic events, the time spent hyperglycaemic, and to evaluate safety with ketosis and changes in glycated haemoglobin. The study also aims to assess the changes in counter-regulatory hormone responses to hypoglycaemia evaluated by a hyperinsulinaemic hypoglycaemic clamp in a subgroup of patients with impaired awareness. Validated questionnaires are used to measure the fear of hypoglycaemia and the impact on the quality of life to assess burden of the disease.

ETHICS AND DISSEMINATION

Ethics committee permissions were gained from respective Institutional Review boards. The findings of the study will provide high quality evidence of the ability of the system in the prevention of hypoglycaemia in real life.

TRIAL REGISTRATION NUMBER

ACTRN12614000510640, Pre-results.

Basal Ganglia Iron in Patients with Multiple Sclerosis Measured with 7T Quantitative Susceptibility Mapping Correlates with Inhibitory Control

BACKGROUND AND PURPOSE

T2 hypointensity in the basal ganglia of patients with MS has been associated with clinical progression and cognitive decline. Our objectives were the following: 1) to compare signal in T2WI, R2 (ie, 1/T2), and R2* (ie, 1/T2*) relaxation rates and quantitative susceptibility mapping; and 2) to investigate the associations among MR imaging, clinical scores, and cognitive measures of inhibitory control linked to basal ganglia functioning.

MATERIALS AND METHODS

Twenty-nine patients with MS underwent a battery of neuropsychological tests including the Flanker and Stroop tasks. 7T MR imaging included 3D gradient-echo and single-echo multishot spin-echo EPI. Quantitative susceptibility mapping images were calculated by using a Wiener filter deconvolution algorithm. T2WI signal was normalized to CSF. R2 and R2* were calculated by log-linear regression. Average MR imaging metrics for the globus pallidus, putamen, and caudate were computed from manually traced ROIs including the largest central part of each structure.

RESULTS

Marked spatial variation was consistently visualized on quantitative susceptibility mapping and T2/T2*WI within each basal ganglia structure. MR imaging metrics correlated with each other for each basal ganglia structure individually. Notably, caudate and putamen quantitative susceptibility mapping metrics were similar, but the putamen R2 was larger than the caudate R2. This finding suggests that tissue features contribute differently to R2 and quantitative susceptibility mapping. Caudate and anterior putamen quantitative susceptibility mapping correlated with the Flanker but not Stroop measures; R2 did not correlate with inhibitory control measures. Putamen quantitative susceptibility mapping and caudate and putamen R2 correlated with the Expanded Disability Status Scale.

CONCLUSIONS

Our study showed that quantitative susceptibility mapping and R2 may be complementary indicators for basal ganglia tissue changes in MS. Our findings are consistent with the hypothesis that decreased performance of basal ganglia-reliant tasks involving inhibitory control is associated with increased quantitative susceptibility mapping.

Fragility non-hip fracture patients are at risk

INTRODUCTION

Fragility fractures are a growing worldwide health care problem. Hip fractures have been clearly associated with poor outcomes. Fragility fractures of other bones are common reasons for hospital admission and short-term disability, but specific long-term outcome studies of non-hip fragility fractures are rare. The aim of our trial was to evaluate the 1-year outcomes of non-hip fragility fracture patients.

METHODS

This study is a retrospective cohort review of 307 consecutive older inpatient non-hip fracture patients. Patient data for analysis included fracture location, comorbidity prevalence, pre-fracture functional status, osteoporosis treatments and sociodemographic characteristics. The main outcomes evaluated were 1-year mortality and post-fracture functional status.

RESULTS

As compared to the expected mortality, the observed 1-year mortality was increased in the study group (17.6 vs. 12.2 %, P = 0.005). After logistic regression, three variables remained as independent risk factors for 1-year mortality among non-hip fracture patients: malnutrition (OR 3.3, CI 1.5-7.1), Charlson comorbidity index (CCI) (OR 1.3, CI 1.1-1.5) and the Parker Mobility Score (PMS) (OR 0.85, CI 0.74-0.98). CCI and PMS were independent risk factors for a high grade of dependency after 1 year. Management of osteoporosis did not significantly improve after hospitalization due to a non-hip fragility fracture.

CONCLUSION

The outcomes of older non-hip fracture patients are comparable to the poor outcomes of older hip fracture patients, and appear to be primarily related to comorbidities, pre-fracture function and nutritional status. The low rate of patients on osteoporosis medications likely reflects the insufficient recognition of the importance of osteoporosis assessment and treatment in non-hip fracture patients. Increased clinical and academic attention to non-hip fracture patients is needed.

Urinary incontinence and poor functional status in fragility fracture patients: an underrecognized and underappreciated association

PURPOSE/INTRODUCTION

Urinary incontinence (UI) affects some 20 % of community-dwelling older people and 30-60 % of people in institutional care. UI is known as an independent predictor of falls, and likely impacts fracture rates. The aim of the study was to measure the prevalence of UI in a typical fragility fracture population, to evaluate the relationship of UI with functional disability in the post-acute setting.

METHODS

Our study is a retrospective cross-sectional study of patients admitted to rehabilitation setting after inpatient hospital management for a fragility fracture. We included all consecutively admitted fragility fracture patients aged over 65. All patients underwent standard clinical examination and Geriatric Assessment. We assessed UI using a two-stage process with a six-item UI screening questionnaire followed by an interview.

RESULTS

1,857 (80.7 % female) patients were available for analysis, mean age was 81.7 years. UI was identified in 59.2 % of all fragility fracture patients, and was more prevalent in females. Patients suffering from UI differed significantly in almost all measured functional and cognitive tests, with increased dependency/lower ADL scores, increased rates of immobility, and higher rates of cognitive dysfunction and depression.

CONCLUSION

This study confirms the high prevalence of UI in older fragility fracture patients, and the association between UI and functional impairments. The diagnostic work-up and treatment of patients should be focused on the special needs of these older patients. More efforts are needed to increase awareness about prevalence and consequences of UI among older fragility fracture patients.

Treatment of osteoporosis in older adults

Osteoporosis is characterized by low bone mineral density and associated with low impact skeletal fractures most often involving the spine, hip, pelvis, proximal humerus and forearm. It is predominantly a disease of ageing, affecting primarily postmenopausal women, but also older men. Both hip and non-hip fractures are associated with excess mortality post-fracture. Fragility fractures can be acutely and subacutely life threatening for many older patients. Postmenopausal osteoporosis has a big impact on health care expenses, with associated spending expected to double for osteoporosis by the year 2050. Despite the severe medical and socioeconomic consequences of fragility fractures, treatment and prevention efforts remain inadequate, particularly in the oldest and highest-risk patients. Osteoporosis is still viewed as an inevitable consequence of aging, rather than an opportunity for treatment and prevention. Multiple factors contribute to the failure of initiating appropriate treatment for osteoporosis, even in patients with fragility fractures. Our review offers an overview of the current literature and offers answers common issues in the management of osteoporosis in older adults.

Community-associated methicillin-resistant Staphylococcus aureus skin infections in a religious community

In September 2004, an outbreak of community-associated methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections (SSTI) was reported among members of a religious community. We conducted a retrospective cohort study on all 175 community members; performed a nasal carriage survey, and environmental swab testing. We identified 24 MRSA cases (attack rate 14%). In multivariate analysis, sauna use [odds ratio (OR) 19.1, 95% confidence interval (CI) 2.7-206.1] and antimicrobial use within 12 months before infection (OR 11.7, 95% CI 2.9-47.6) were risk factors for infection. MRSA nasal carriage rate was 0.6% (1/174). Nine of 10 clinical isolates and an isolate from an administrative office within the community had the pulsed-field gel electrophoresis type USA300. Targeted hygiene improvement, wound care, and environmental cleaning were implemented. We describe the first reported outbreak of MRSA SSTI in a religious community. Adherence to appropriate personal and environmental hygiene might be critical factors in controlling transmission.

Fluid balance and renal response following dehydrating exercise in well-trained men and women

We examined the recovery of plasma volume, plasma osmolality, renal water and sodium handling and fluid-regulating hormones to dehydrating exercise in well-trained women and compared them to men. Ten male and eight female athletes cycled at anaerobic threshold at an ambient temperature of 32 degrees C until dehydration by 3% of their body mass (mb). After exercise, they drank water equal to 1% mb and rested for 240 min. Plasma renin activity (PRA), serum aldosterone [ALDO]s, plasma arginine vasopressin [AVP]pl, norepinephrine concentrations and plasma osmolality (Osmpl) were determined at baseline, end of exercise, 30, 60, 120 and 240 min postexercise. Urine was collected at baseline, end of exercise, 60, 120 and 240 min postexercise. Renal free water and sodium handling were assessed. The recovery of OSMpl and plasma volume occurred within the first 60 min of recovery and at similar rates between the groups. However, women had lower PRA at the end of exercise (P = 0.05), an earlier recovery of [ALDO]s, and a slower [AVP]pl recovery. Overall fluid balance was similar between the men and women, as were the early recovery of renal free water clearance (CH2O). During the last 120 min of recovery CH2O was more negative (greater water reabsorption) and fractional sodium excretion was increased in the women compared to the men. Despite small differences in sodium and water reabsorption following dehydration, it appears from other study that recovery from dehydrating exercise in well-trained men and women is remarkably similar.

Systemic effects of ingesting varying amounts of a commercial carbohydrate beverage postexercise

OBJECTIVE

Although the role of postexercise carbohydrate intake in the replenishment of muscle glycogen is well established, large amounts of carbohydrate may affect other systems which are recovering from exercise as well.

METHODS

We varied the timing and amount of a commercial glucose polymer/fructose (CHO) beverage ingested postexercise in 2 groups of 8 normotensive men following 1 hour of cycling exercise. In Study A the subjects ingested 1 L of a 200 g CHO solution or 1 L of water (W) immediately postexercise. The participants in Study B consumed 1 L of a 1.5 g/kg CHO solution, or W, immediately and 2 hours postexercise.

RESULTS

Recovery systolic blood pressure was elevated after 200 g CHO as compared to water, but not after 1.5 g/kg CHO. Diastolic blood pressure was decreased, while heart rate, insulin and glucose increased following both doses of CHO. Despite the potassium (K) content of the beverages, serum K decreased in Study A and B, while a trend was noted following CHO for decreased urinary K excretion at 2 hours and for increased sodium excretion at 4 hours in Study B. Post CHO aldosterone declined more rapidly than after W, and urine volumes were decreased compared to W in both studies 2 hours after CHO.

CONCLUSIONS

We speculate that hyperinsulinemia contributed to the rapid decline in K and aldosterone by creating a flux of K to the intracellular space. It appears that CHO ingestion postexercise results in systemic effects that are related to the amount and timing of CHO consumed.

Shoulder weakness in professional baseball pitchers

The purposes of this study were to: 1) compare shoulder range of motion and strength in professional baseball pitchers (N = 47) compared with age-matched controls (N = 16), and 2) examine the relationship of injury history to strength and range of motion. Based on injury history pitchers were categorized as: 1) none (N = 26), 2) injury requiring conservative intervention (N = 9), or 3) injury requiring surgical intervention (N = 12). Range of motion was measured for internal rotation (IROM) and external rotation (EROM). Eccentric strength was measured by hand-held dynamometer for internal rotation (IR), external rotation (ER), abduction (ABD), and supraspinatus muscle (SUP) strength. Injury history had no effect on strength and range of motion. Dominant EROM was greater in pitchers, P < 0.0001, and controls, P < 0.05, with pitchers having greater EROM motion bilaterally, P < 0.0001. Pitchers were weaker in SUP on the dominant vs nondominant side, P < 0.0001, and on the dominant side for weight adjusted ER, ABD, P < 0.01, and SUP, P < 0.0001, compared with controls. In conclusion, dominance and pitching resulted in soft tissue adaptation. Pitchers displayed weakness in three of four tests by comparison with controls, suggesting that the demands of pitching are insufficient to produce eccentric strength gains and may in fact lead to weakness. Dominant-side SUP weakness in pitchers may reflect subclinical pathology or chronic fatigue.

The effect of stabilization on isokinetic knee extension and flexion torque production

The purpose of this study was to examine the effect of four methods of stabilization on maximal reciprocal isokinetic knee extension and flexion. Left knee extension/flexion was tested at 60 degrees /s in 20 subjects. Warm-up consisted of five submaximal and one maximal effort followed by three maximal efforts in each of four randomized stabilization conditions: 1) Hands and back stabilization; the trunk was strapped to the back rest and the hands grasped the seat. 2) Back stabilization; the trunk was strapped to the back rest and the hands were folded across the chest. 3) Hand stabilization; the hands grasped the seat and the back rest was removed. 4) No stabilization; the hands were folded across the chest and the back rest was removed. One-way repeated measures ANOVA showed a significant effect of stabilization for knee extension (F(3,57)=17.44, p=.0001) and knee flexion (F(3,57)= 5.37, p=.002). Paired, two-tailed student's t-tests with Bonferroni correction showed that, in knee extension, no stabilization was significantly less than all others, p<.001. In addition, back stabilization was less than hands and back stabilization, p<.005. In knee flexion, no stabilization was significantly less than all others, p<.01. In conclusion, the method of trunk stabilization significantly affected maximal reciprocal isokinetic knee extension/flexion strength measurements. Maximal knee extension/flexion torque production was achieved when the trunk was strapped to the back support and when the hands grasped the seat.

Viscoelastic stress relaxation in human skeletal muscle

Viscoelastic stress relaxation refers to the decrease in tensile stress over time that occurs when a body under tensile stress is held at a fixed length. The purpose of this study was to demonstrate viscoelastic stress relaxation in human skeletal muscle. Resistance to stretch (tensile force), hip flexion range of motion (ROM), and reflex contractile activity (IEMG) of the hamstring muscle group were measured during a passive straight leg raise. The testing protocol involved a first stretch to the maximum tolerated ROM with the lower extremity held at that point for 45 s (test 1). All 15 subjects tested (9 men, 6 women) had a stretch induced EMG response. The onset of a sustained EMG response occurred at a specific hip flexion angle in 10 subjects. These 10 subjects (6 men, 4 women) underwent a second straight leg raise stretch (test 2) to a ROM 5 degrees below the ROM at which the onset of EMG activity occurred in test 1. The stretch was held at this hip flexion angle for 45 s. There was a significant decrease in force at final ROM during the 45 s in test 1 (11.35 +/- 1.75 N, P < 0.0001) and in test 2 (4.2 +/- 1.55 N, P < 0.05). The percent decrease from the force at the respective final ROM was not significantly different between the tests (14.4 +/- 2.2% in test 1 and 13 +/- 2.3% in test 2). In test 1 there was a significant decrease over time in IEMG of 59.71 +/- 16.01 microV.s (P < 0.01) which was not significantly correlated to the decrease in force.(ABSTRACT TRUNCATED AT 250 WORDS)

Sucrose ingestion following exercise: selected cardiovascular, hormonal, renal, and metabolic effects

Carbohydrates, frequently consumed following exercise for glycogen resynthesis, have been shown to have other systemic effects in resting men. We examined the effects of postexercise sucrose (a disaccharide carbohydrate) ingestion on the renal, cardiovascular, and sympathetic nervous systems. Eight men consumed 1 l of water (W) or 1 l of a 200 g sucrose solution (S) following 1 hour of bicycle exercise at 70% heart rate reserve. Measurements were made during 2 hours of recovery. Heart rate and systolic blood pressure were elevated following S as compared to W (p < 0.009, p < 0.04, respectively). Diastolic blood pressure was lower after S (p < 0.04) and mean blood pressure did not differ between beverages. Plasma and urinary catecholamines decreased similarly after exercise regardless of treatment. After S insulin (p = 0.0019) and glucose (p = 0.0036) were increased but serum aldosterone (p = 0.0083) and potassium (p = 0.0285) responses were lower. No differences were observed for plasma renin activity. Urine volume and kaliuresis were less after S (p = 0.03, p = 0.03). A 24% increase in metabolic rate (p = 0.002) and increased respiratory exchange ratio (p = 0.02) after S were observed. Systemic effects of sucrose ingestion following exercise include cardiovascular, renal, endocrine, and metabolic changes.

A novel, spectrophotometric microneutralization assay for respiratory syncytial virus

We describe a simple and rapid microneutralization assay for respiratory syncytial virus (RSV) based on the colorimetric quantitation of the conversion of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) to a formazan product by the mitochondria of viable cells. Conditions for RSV infectivity were first optimized for sensitivity and reproducibility based on cell density and on RSV concentration as a function of multiplicity of infection (MOI) and time post-infection and the resulting optical densities were shown to be inversely proportional to MOI. For RSV neutralization, dilutions of heat-inactivated human plasma were preincubated with RSV and complement prior to infection of cells in microtiter plates. Following MTT dye conversion, 50% RSV neutralization titers were determined by linear regression analysis of the optical density values and endpoints were markedly influenced by MOI. The MTT-based assay was shown to be comparably sensitive to the plaque reduction assay for quantitation of neutralizing antibody, but more readily adaptable to the screening of a large number of samples. Finally, we demonstrated that the MTT microneutralization assay for RSV was useful for quantitation assay of neutralization activity in sera of mice and cotton rats.

Monitoring training status in professional ballet dancers

Methods of non-invasive monitoring of training status for prevention of staleness in athletes and dancers need to be developed and evaluated. In order to monitor physiologic and psychologic changes which may result from overstraining, we measured urinary excretion of free norepinephrine (NE) and epinephrine (E) and mood states over 5 weeks of an intensive ballet season in 12 (6 men, 6 women) professional dancers. First morning urine voids (AM) were collected at the start of the season and following the only off-day each week with final collection on the last day of the season. Additional urine samples were collected before (pre) and after (post) each dancer's subjectively-rated single most difficult performance. Profile of Mood States (POMS) was completed by and collected from each dancer at the same time as the AM urine samples. NE and E excretions (nanograms per mg creatinine) increased significantly with time (r = 0.91, p less than 0.02, and r = 0.94, p less than 0.01, respectively) from beginning to end of season, and pre to post (51.1 +/- 7.3 to 115.6 +/- 19.7, p less than 0.001 and 19.3 +/- 3.2 to 37.7 +/- 4.2, p less than 0.001, respectively). Women had a significantly higher excretion of NE than did men (F = 9.33, p = 0.014) and no gender differences existed in the excretion of E (F = 0.57, p = 0.484).(ABSTRACT TRUNCATED AT 250 WORDS)

Predictive accuracy of criteria used to assess maximal oxygen consumption

To evaluate criteria frequently used to designate an exercise test as maximal, 33 men and 18 women completed progressive incremental cycle ergometry to exhaustion with direct measurement of oxygen consumption (VO2). On a separate day, subjects exercised at 115% of the maximal work rate attained in the first test following a 5-minute warm-up. If VO2 exceeded that of the progressive test by greater than or equal to 150 ml/min, subjects returned on a third day and pedalled at 125% of the first day's work ratepeak. This procedure was repeated until VO2 increased less than 150 ml/min, and defined whether the progressive test was a maximal or nonmaximal test. There were 45 tests that met the criterion for maximum during the progressive test and six nonmaximal tests. Respiratory exchange ratio and 85% age-predicted maximal heart rate were sensitive criteria for a maximal test but were not specific. Attainment of age-predicted maximal heart rate and peak lactate greater than 8 mmol/L were highly specific but insensitive measures of a maximal test. In the absence of a VO2 plateau, age-predicted maximal heart rate and lactate greater than 8 mmol/L can be used as indicators of maximal tests with a high degree of confidence. When age-predicted maximal heart rate or lactate greater than 8 mmol/L are not attained, the test may still be maximal because negative predictive value is low.

Effects of a soluble CD4 and CD4-Pseudomonas exotoxin A chimeric protein on human peripheral blood lymphocytes: lymphocyte activation and anti-HIV activity in vitro

Recombinant sCD4-based proteins were evaluated for their effects on antigen-stimulated proliferation of human peripheral blood mononuclear cells (PBMC) and for antiviral activity against PBMC infected with human immunodeficiency virus (HIVD34). Two sCD4-based proteins were solubilized, refolded, and purified to homogeneity from recombinant E. coli and consisted of the 178 amino-terminal residues of CD4 fused with the translocating and catalytic domains of Pseudomonas exotoxin A (sCD4-PE40) or 183 amino-terminal residues of CD4 (sCD4-183); a third sCD4 consisting of 369 amino acids of CD4 was purified from recombinant mammalian cells for comparative purposes (sCD4-369). Increasing molar concentrations of these sCD4s were evaluated for inhibition of PBMC proliferation induced by alloantigen (MLR), by tetanus toxoid (TTOX), or in response to crosslinking with antibody to CD3 (OKT3). In addition, the concentrations of each protein required to inhibit replication of the HIVD34 isolate in primary PBMC was determined by quantitation of HIV p24 antigen released into supernatant fluids by infected cells. By comparing antiviral activity with anti-proliferative activity a relative estimate of the selectivity index for each recombinant sCD4 was determined. Proliferation of PBMC in response to alloantigen or OKT3 was less sensitive to inhibition than proliferation induced by TTOX, and the selectivity indices estimated for sCD4-PE40 were 170, 170 and 17, respectively. The selectivity index for sCD4-183 was greater than 350 under all assay conditions. Comparative evaluation of alloantigen-stimulated proliferation with antiviral activity of sCD4-183 versus sCD4-369 suggested that the E. coli-derived sCD4-183 may have a higher selectivity index under these conditions than its mammalian cell-derived counterpart.

Soluble CD4-PE40 is cytotoxic for a transfected mammalian cell line stably expressing the envelope protein of human immunodeficiency virus (HIV-1), and cytotoxicity is variably inhibited by the sera of HIV-1-infected patients

Sera were obtained from 50 individuals infected with human immunodeficiency virus type 1 or from HIV-1-uninfected individuals before or after vaccination with recombinant gp160. These sera were evaluated for activity antagonistic to the cell-killing activity of the chimeric Pseudomonas exotoxin hybrid protein, sCD4-PE40. For these studies, Chinese hamster ovary (CHO) cells were transfected with a chimeric plasmid encoding the tat, rev, and envelope genes of HIV-1 and a cell line was selected for stable expression of the envelope glycoproteins at the cell surface (CHO-env). Cytotoxicity of sCD4-PE40 for CHO-env in the presence or absence of added human serum was quantitated spectrophometrically following enzymatic reduction of a tetrazolium bromide within the mitochondria of viable cells (MTT assay). Several HIV+ sera inhibited the cytotoxic activity of sCD4-PE40; the antagonist had properties consistent with those of immunoglobulins in that it was heat stable, absorbed by protein A, and reversible by increasing the concentration of sCD4-PE40. Of 15 HIV+ sera which strongly reacted with gp120, 11 (73%) also potently inhibited sCD4-PE40 cytotoxicity, and cytotoxicity was inhibited by sera from some HIV- individuals after, but not before, immunization with gp160. These data suggested a role for antibody to gp120 in the antagonistic activity. However, not all sera with antibody to gp120 antagonized sCD4-PE40 cytotoxicity and high levels of antagonist activity were frequently (40%) found in HIV+ sera lacking immunoblot-detectable antibody to gp120, or antibody to either CD4 or PE40. Grouping of the HIV+ sera according to the patients' absolute number of CD4+ cells revealed that the degree of inhibition of sCD4-PE40 cytotoxicity approached a Gaussian distribution, suggesting that persons with CD4+ cell counts between 200 and 700/mm3 may be more likely to possess significant levels of serum antagonist. This data have implications for the clinical development of sCD4-PE40 or other sCD4-based therapeutics in the management of HIV-1 infection.

Immunodominant T-cell epitope on the F protein of respiratory syncytial virus recognized by human lymphocytes

The lymphocyte proliferative responses to respiratory syncytial virus (RSV) were evaluated for 10 healthy adult donors and compared with proliferative responses to a chimeric glycoprotein (FG glycoprotein) which consists of the extracellular domains of both the F and G proteins of RSV and which is produced from a recombinant baculovirus. The lymphocytes of all 10 donors responded to RSV, and the proliferative responses to the whole virus were highly correlated with the responses to the FG glycoprotein. These data suggested that one or both of these glycoproteins of RSV were major target structures for stimulation of the human lymphocyte proliferative response among virus-specific memory T cells. The lymphocytes of four donors were evaluated further for their proliferative responses to a nested set of overlapping peptides modeled on the extracellular and cytoplasmic domains of the F protein of RSV. Strikingly, the lymphocytes of all 4 donors responded primarily to a region defined by a single peptide spanning residues 338 to 355, and the lymphocytes of 2 donors responded to an overlapping peptide spanning residues 328 to 342 also, thus defining a region of the F1 subunit within residues 328 to 355 that may circumscribe an immunodominant site for stimulation of human T cells from a variety of individuals. This region of the F protein is highly conserved among A and B subgroup viruses. As revealed by monoclonal antibody blocking studies, the lymphocytes responding to this antigenic site had characteristics consistent with T helper cells. Similar epitope mapping studies were performed with BALB/c mice immunized with the FG protein in which a relatively hydrophobic peptide spanning residues 51 to 65 within the F2 subunit appeared to be the major T cell recognition determinant. The data are discussed with respect to an antigenic map of the F protein and the potential construction of a synthetic vaccine for RSV.

Cytotoxic T cell activity against the 22-kDa protein of human respiratory syncytial virus (RSV) is associated with a significant reduction in pulmonary RSV replication

Recombinant vaccinia viruses expressing the RSV F glycoprotein (Vac-F), or a previously described chimeric protein consisting of the extracellular domains of the F and G glycoproteins (Vac-FG), or the 22-kDa membrane protein (Vac-22 kDa) were evaluated for their ability to protect BALB/c mice against infection by RSV subgroup A or subgroup B viruses and for their ability to induce a humoral immune response or a cytolytic T lymphocyte (CTL) response. Immunization with Vac-F or Vac-FG fully protected mice against challenge with RSV of subgroup A or B and induced high levels of both humoral and CTL-mediated immunity. Immunization with Vac-22 kDa partially to fully protected mice against challenge with RSV of subgroup A or B, depending on the immunization and challenge conditions, and induced a potent CTL response in the apparent absence of a significant humoral response. These vectors fortuitously allowed us to evaluate the contribution of a protein-specific memory CTL response to subgroup-specific and subgroup-cross-reactive reductions in pulmonary RSV replication independently from a humoral response. Our data suggest that 22-kDa-specific CTL contribute significantly to the reduction of RSV within the lung, but that complete protection also requires a humoral component.

Gender differences in the systolic blood pressure response to exercise

Previous work has shown a gender difference in the normal cardiac response to exercise. Men had significantly higher absolute systolic blood pressure responses at 50%, 75%, and 100% peak heart rate on all modalities (p less than 0.05). This difference is absent when systolic blood pressure is adjusted for body surface area, is reduced when adjusted for body weights, and is reversed when systolic blood pressure is adjusted for lean body mass. The influence of gender on the systolic blood pressure response to dynamic exercise was independent of exercise modality. Men had a higher systolic blood pressure in spite of the fact that they had similar sympathetic nervous system response as indicated by urinary norepinephrine excretion. Gender differences in systolic blood pressure responses were altered when adjusted for body weight, body surface area, and lean body mass.

The influence of flexibility on the economy of walking and jogging

The relationship of 11 measures of trunk and lower limb flexibility to the economy of treadmill walking and jogging as measured by steady-state oxygen consumption (VO2) was studied. Subjects (38 women, 62 men, aged 20-62 years) were tested at six speeds between 53.6 and 187.7 m/min. By combining scores from all flexibility tests, and beginning at speeds of 107.3 m/min, the "tightest" third used significantly less O2/m/kg (9%, p less than 0.05) than the "loosest" third, with "normals" in between. Two tests, trunk rotation and lower limb turnout, gave the best separation for walking/jogging economy, with the "tightest" third differing significantly from the "loosest" (8-12%) at all speeds tested (ANOVA with Scheffe). We conclude that nonpathological musculoskeletal tightness was associated with a decreased steady-state VO2 for treadmill walking and jogging.

Cytolytic T-lymphocyte responses to respiratory syncytial virus: effector cell phenotype and target proteins

Cytolytic T-lymphocyte (CTL) activity specific for respiratory syncytial (RS) virus was investigated after intranasal infection of mice with RS virus, after intraperitoneal infection of mice with a recombinant vaccinia virus expressing the F glycoprotein, and after intramuscular vaccination of mice with Formalin-inactivated RS virus or a chimeric glycoprotein, FG, expressed from a recombinant baculovirus. Spleen cell cultures from mice previously infected with live RS virus or the F-protein recombinant vaccinia virus had significant CTL activity after one cycle of in vitro restimulation with RS virus, and lytic activity was derived from a major histocompatibility complex-restricted, Lyt2.2+ (CD8+) subset. CTL activity was not restimulated in spleen cells from mice that received either the Formalin-inactivated RS virus or the purified glycoprotein, FG. The protein target structures for recognition by murine CD8+ CTL were identified by using target cells infected with recombinant vaccinia viruses that individually express seven structural proteins of RS virus. Quantitation of cytolytic activity against cells expressing each target structure suggested that 22K was the major target protein for CD8+ CTL, equivalent to recognition of cells infected with RS virus, followed by intermediate recognition of F or N, slight recognition of P, and no recognition of G, SH, or M. Repeated stimulation of murine CTL with RS virus resulted in outgrowth of CD4+ CTL which, over time, became the exclusive subset in culture. Murine CD4+ CTL were highly cytolytic for RS virus-infected cells, but they did not recognize target cells infected with any of the recombinant vaccinia viruses expressing the seven RS virus structural proteins. Finally, the CTL response in peripheral blood mononuclear cells of adult human volunteers was investigated. The detection of significant levels of RS virus-specific cytolytic activity in these cells was dependent on at least two restimulations with RS virus in vitro, and cytolytic activity was derived primarily from the CD4+ subset.

Subject variability of shoulder abduction strength testing

To quantify normal biological variability of shoulder abduction strength testing with an isokinetic and a hand-held dynamometer, we tested nine healthy subjects over a clinically relevant period. One side was tested with a Cybex at 60 deg/sec and the other with a hand-held dynamometer. Six maximal trials, following warmup, were conducted on each of 5 days, separated by 1 to 2 weeks. Intraday correlations of individual trials ranged from 0.82 to 0.995 for hand-held dynamometer, and 0.88 to 0.996 for Cybex. Interday correlations ranged from 0.94 to 0.98 for hand-held dynamometer, and 0.88 to 0.97 for Cybex. The best values to use for Cybex interday variability were the average of the first three repetitions, and yielded standard errors of 8.6% to 19.2% of the sample mean. The average of the last three repetitions were the best for hand-held dynamometers, and yielded standard errors of 5.5% to 10.8%. There was a significant decline (P less than 0.05) in strength of the mean of the last three versus the mean of the first three daily repetitions on Day 1 and 4 for hand-held dynamometers, and a trend toward this on the other days, that was not seen with Cybex. Regression of average Day 1 values for Cybex and hand-held dynamometer yielded r = 0.86 (P less than 0.01) with a slope of 1.07 indicating good agreement between modalities. In conclusion, intraday/interday correlations were high for Cybex and hand-held dynamometer. Interday variability was minimized by using the mean score of the first three and last three repetitions for Cybex and hand-held dynamometer, respectively. Changes in Cybex and hand-held dynamometer strength of less than 19% and 11%, respectively, are within the area of "measurement error" and should therefore not be considered clinically significant.

Recombinant CD4-Pseudomonas exotoxin hybrid protein displays HIV-specific cytotoxicity without affecting MHC class II-dependent functions

The present study describes several in vitro activities of CD4(178)-PE40, a recombinant protein containing a portion of human CD4 linked to active regions of Pseudomonas aeruginosa exotoxin A. Using assays for cell viability, we demonstrate that the hybrid toxin displays highly selective cytotoxicity for HIV-infected T lymphocytes. In a latently infected human T-cell line which is inducible for HIV expression, toxin sensitivity is observed only upon virus induction. At concentrations which readily kill HIV-infected T cells, CD4(178)-PE40 has no observable cytotoxic effects on uninfected human cell lines expressing surface major histocompatibility complex (MHC) Class II molecules, and does not interfere with cellular responses known to be dependent on functional association between CD4 and MHC Class II molecules.

Synthetic immunogens constructed from T-cell and B-cell stimulating peptides (T:B chimeras): preferential stimulation of unique T- and B-cell specificities is influenced by immunogen configuration

In our effort to develop synthetic immunogens as vaccines, we have focused on the combination of a known T-cell stimulating peptide with putative B-cell stimulating peptide epitopes derived from the sequences of respiratory syncytial (RS) virus proteins. The T-cell stimulating peptide consists of residues 45 through 60 of the 1A protein of RS virus, and it also contains an overlapping antibody binding (B-cell) site. Herein, we have combined the 1A T-cell stimulating peptide with a putative B-cell peptide epitope derived from the viral G glycoprotein using linear synthesis or using chemical crosslinking. The chimeric immunogens were compared to each other and to free peptides for their T- and B-cell stimulating properties. Both chimeras had potent T-cell stimulating and antibody-inducing activity. However, T-cells primed to free peptide differentially recognized the two chimeras and immunization with the chimeras primed T-cells with different specificity. Most strikingly, the two chimeras had opposite antibody-inducing properties: The chimera constructed by linear synthesis overwhelmingly elicited antibody directed against the G peptide, whereas the chimera constructed by chemical crosslinking overwhelmingly elicited antibody directed against the 1A peptide. Competition blocking studies revealed that the chimeras adopted different configurations in solution. The resulting antibody response, and hence the B-cell clone elicited, was consistent with the antibody accessibility of the individual peptide epitope.

Musculoskeletal Risk Factors in the Young Athlete

In brief: Many children and adolescents participate in sports that put them at risk for musculoskeletal injuries. Underlying physical conditions, or risk factors, may predispose them to particular types of sports injuries. Research shows that these risk factors fall into five categories: body type, flexibility, muscle strength, inadequate rehabilitation of a previous injury, and skeletal malalignment and anomalies. Some findings show, for example, that youthful football players who are also heavy have an increased rate of injury, sprains and strains are less common in flexible athletes, and patellar pain or subluxation may be related to a variety of malalignment factors. The authors recommend using a systematic, integrated approach to risk assessment of the athlete, both for detecting risk factors and determining their potential for con tribu ting to a sports injury.

A 16-amino acid peptide of respiratory syncytial virus 1A protein contains two overlapping T cell-stimulating sites distinguishable by class II MHC restriction elements

The 1A protein of respiratory syncytial (RS) virus is a small, 64-amino acid hydrophobic protein expressed in infected cells. We previously showed that the C-terminal domain of 1A contained a site for stimulation of RS virus-reactive Th lymphocytes in BALB/c and SJL/J mice. In this report we modeled a series of overlapping synthetic peptides of the 1A protein and we present evidence to suggest that the C-terminal domain of the 1A protein contains not one, but two, Th lymphocyte-stimulating sites. Although these sites are extensively overlapping they can be distinguished on the basis of presentation by distinct class II restriction elements of the murine MHC. Additionally, we present evidence to suggest that a 16-amino acid synthetic peptide which contains both of these T cell sites can stimulate T cell activity in mice of multiple different class II MHC haplotypes, perhaps representing a potential lead for designing a "universal" T cell stimulator.

A 16-amino acid peptide of respiratory syncytial virus 1A protein contains two overlapping T cell-stimulating sites distinguishable by class II MHC restriction elements

The 1A protein of respiratory syncytial (RS) virus is a small, 64-amino acid hydrophobic protein expressed in infected cells. We previously showed that the C-terminal domain of 1A contained a site for stimulation of RS virus-reactive Th lymphocytes in BALB/c and SJL/J mice. In this report we modeled a series of overlapping synthetic peptides of the 1A protein and we present evidence to suggest that the C-terminal domain of the 1A protein contains not one, but two, Th lymphocyte-stimulating sites. Although these sites are extensively overlapping they can be distinguished on the basis of presentation by distinct class II restriction elements of the murine MHC. Additionally, we present evidence to suggest that a 16-amino acid synthetic peptide which contains both of these T cell sites can stimulate T cell activity in mice of multiple different class II MHC haplotypes, perhaps representing a potential lead for designing a "universal" T cell stimulator.

Monoclonal antibodies that cross-react with the E1 glycoprotein of different alphavirus serogroups: characterization including passive protection in vivo

A panel of four monoclonal antibodies (mAb) were produced that cross-react with representatives of two different togavirus serogroups, namely sindbis (SIN) and Semliki Forest (SF) viruses, by ELISA and ADCMC assays. Three of these mAb, IgG2a and IgG2b isotypes, passively protected C3H/Hej mice against 10 and 100 LD50 of SF challenge and one, IgM, did not protect against either challenge dose, or even at 1 LD50. All these mAb were cross-reactive with the E1 glycoprotein of the viruses by immunoblotting in which three different patterns of reactivity were evident, suggesting that three epitopes were involved. The patterns depended upon whether the mAb recognized E1 extracted from purified virions or infected cells and whether SDS-PAGE and immunoblotting were done in the presence or absence of beta-mercaptoethanol. One mAb (IgM) reacted with nonreduced or reduced E1 from either virions or cells suggesting recognition of a linear epitope. The other three mAb reacted with nonreduced but not reduced E1 from virions suggesting that recognition depends upon conformational epitopes. These three mAb reacted also with nonreduced E1 extracted from SF-infected cells whereas only one reacted with nonreduced E1 extracted from SIN-infected cells.

Exercise-related changes in serum catecholamines and potassium: effect of sustained exercise above and below lactate threshold

Plasma potassium and catecholamines exhibit rapid shifts during exercise testing, particularly when exercise intensity exceeds lactate threshold. To assess changes that may occur during sustained exercise, we studied 10 healthy men to determine the effect of 20 minutes of exercise at 25 W above lactate threshold (ALT) and 20 minutes of exercise at 25 W below lactate threshold (BLT). Both conditions showed elevation of catecholamines at end exercise compared to baseline, but catecholamine levels ALT were significantly higher than the levels BLT (2270 +/- 190 versus 900 +/- 230 pg/ml norepinephrine, p less than 0.001; 509 +/- 69 versus 150 +/- 18 pg/ml epinephrine, p less than 0.001). This difference persisted at 2 minutes of recovery (1620 +/- 130 versus 590 +/- 60 pg/ml norepinephrine, p less than 0.001; 216 +/- 31 versus 98 +/- 16 pg/ml epinephrine, p less than 0.001). Both conditions resulted in a significant elevation in potassium at end exercise compared to baseline, but the potassium levels ALT were significantly higher than the levels BLT (1.1 +/- 0.1 mEq/L versus 0.5 +/- 0.1 mEq/L, p less than 0.001. The fall in potassium in the immediate post-exercise period was significantly greater following exercise ALT (-0.8 +/- 0.1 mEq/L versus -0.2 +/- 0.1 mEq/L, p less than 0.001). Thus sustained exercise slightly ALT resulted in a significant potassium flux and very elevated catecholamine levels. Avoiding these metabolic stresses by exercising BLT may decrease chances for exercise-related arrhythmia or other cardiac dysfunction in susceptible patients.

Metabolic costs and heart rate responses to treadmill walking in water at different depths and temperatures

Treadmill walking/jogging in water is a potentially useful therapeutic modality. Since energy costs of this activity are unknown, we compared oxygen consumption (VO2) of treadmill walking/jogging in water to a dry treadmill at speeds of 40.23 to 160.9 meters/min (m/m) in 13.4 m/m increments in 11 subjects. At speeds greater than or equal to 53.6 m/m, ankle depth, below knee, midthigh, and waist depth walking/jogging in water significantly elevated VO2 and heart rate (HR) above dry treadmill walking (P less than 0.05). At speeds greater than or equal to 134.1 m/m, VO2 of waist depth jogging was not significantly greater than dry jogging. These findings showed no gender specificity. Treadmill walking/jogging in waist depth water at temperatures of 30.5 degrees C and 36.1 degrees C was compared to dry treadmill walking in five subjects. The rate of increase of HR compared to VO2 was significantly greater at 30.5 degrees C than dry walking, and greater at 36.1 degrees C than 30.5 degrees C (P less than 0.05). Treadmill walking in water can double the oxygen cost of movement depending on the depth and speed, and the response to increasing speed is nonlinear. Water temperature affects the relationship of HR to VO2 at waist depth, suggesting that water temperature can add a significant thermal load to the cardiovascular system. Metabolic and cardiovascular demands of treadmill walking/jogging in water must be considered when using this modality since greater external work results at much lower speeds than on land.

Mapping an antibody-binding site and a T-cell-stimulating site on the 1A protein of respiratory syncytial virus

A synthetic peptide modeled on residues 45 to 60 of the 1A protein of respiratory syncytial (RS) virus [1A(45-60)] was constructed and used for immunization of mice and rabbits. The immunoglobulin G fraction of the resulting rabbit antibody, purified on protein A-Sepharose, immunoprecipitated from RS-infected HEp-2 cells a protein with a molecular size of approximately 9.5 kilodaltons, which corresponds to the previously published molecular size of the 1A protein (Y. T. Huang, P. L. Collins, and G. W. Wertz, Virus Res. 2:157-173, 1985). To investigate the T-cell-inducing properties of 1A(45-60), six strains of mice were immunized and their popliteal lymph node cells were tested for proliferation upon restimulation with peptide in vitro. The lymph node cells of all six strains of mice were responsive to restimulation with 1A(45-60) and showed high- and low-responder strain variation. These peptide-primed lymph node cells also proliferated upon in vitro restimulation with RS virus-infected cells. Correlation of proliferation with interleukin 2 production suggested that the responding lymphocytes were T-helper cells. The antibody-binding and T-cell-stimulating sites of 1A were mapped by constructing a series of overlapping synthetic peptides and testing each for ability to react with antiserum prepared by immunization of BALB/C mice with free peptide 1A(45-60) or for ability to restimulate proliferation in 1A(45-60)-primed lymph node cells of BALB/C mice. Human antibody, obtained during confirmed RS virus infection, was similarly tested with the truncated peptides. Antibody-binding activity was reduced after truncation from the carboxy terminus, and a binding site was mapped to residues 51 through 60, the smallest peptide tested. T-cell-stimulating activity in mice was relatively resistant to truncation from the carboxy terminus and sensitive to truncation from the amino terminus. The smallest region which retained significant T-cell-stimulating activity mapped to residues 46 through 56. However, addition of the naturally occurring Cys at residue 45 and extension of the C terminus to residue 62 resulted in maximum T-cell-stimulating activity of the peptide. These data define both a T-cell epitope and a B-cell epitope of the 1A protein of RS virus and suggest that the carboxy terminus of 1A contains a B-cell epitope, involving residues 51 through 60, which is recognized during natural human infection.

A historical perspective of injuries in professional football. Twenty-six years of game-related events

A professional football franchise was studied consecutively from 1960 through 1985 for injuries incurred during regular-season games. A "significant" injury was defined as one requiring the player to miss at least two consecutive games (N = 331) and a "major" injury as one that caused the player to miss at least eight games or the equivalent time (N = 130). Significant injuries averaged 0.89 per game and major injuries 0.35 per game for the entire 26 years. Following a high injury rate prior to 1965, significant injury rates were episodic. Major injuries declined (rs = -.68; P less than .01). Since the team's first games on synthetic surfaces in 1968, there was no difference in the rates of significant injuries per game (0.57 vs 0.67) or major injuries per game (0.22 vs 0.33) between games played on grass or artificial turf, respectively. Since 1969 there has been a decline in major knee injuries (rs = -.51; P less than .05) and a decline in major injuries incurred during special-teams play (rs = -.55; P less than .05). The data indicate that this team suffered fewer injuries with the passing of time, primarily in injuries that caused a player to miss at least eight consecutive games. Observations of short duration do not lend themselves to current media perception that injury rates are higher and more serious today in professional football.

Injuries in youth football

The injury experience of 5,128 boys (8 to 15 years of age, weight 22.5 to 67.5 kg [50 to 150 lb]) participating in youth football revealed an overall rate of significant injury of 5%, with 61% classified as moderate and 38.9% as major injuries. No catastrophic injuries occurred, and it was rare for a permanent disability to result from any injury. The upper extremity was most likely to be injured, and fractures were the most common injury to occur. The rate, site, and type of injuries experienced by the pre- and early adolescent players differed from the pattern for older players at higher levels of competition. Variables related to an increased risk of injury included participation in the older and heavier divisions, heavier weight, and involvement in contact activities. Factors associated with the occurrence of an injury were evaluated and provided areas for future study for the prevention of injuries. The medical care received by youth football participants was appropriate, although improved sideline surveillance for injured players is required.

Comparison of arm and treadmill exercise at 85% predicted maximum heart rate

Both treadmill exercise and arm exercise are used for evaluating coronary artery disease, but arm exercise has lower diagnostic sensitivity. We compared the two exercise modalities with respect to the rate-pressure product at 85% predicted maximal heart rate, a parameter frequently used to denote performance of sufficient exercise to derive clinical conclusions. At this heart rate, treadmill exercise resulted in a significantly greater systemic oxygen consumption (2.7 +/- .8 vs. 2.1 +/- .6 l/min) and rate-pressure product (30.6 +/- 4.4 X 10(3) vs. 28 +/- 3.3 X 10(3)) than arm ergometry. An inability to generate sufficient imbalance of myocardial oxygen supply and demand may account for the relatively higher incidence of false negative exercise tests seen with arm ergometry, especially if the exercise test is stopped when the patient attains 85% predicted maximal heart rate.

The arthroscopic treatment of subacromial impingement

In order to effectively employ arthroscopic techniques for a subacromial decompression, a thorough understanding of the impingement syndrome and its clinical manifestations is necessary. The authors' preliminary experience with the arthroscopic subacromial decompression suggests excellent results with early return to competitive athletics.

Pyrimidinone (bropirimine) mediated alteration of T lymphocyte subsets during murine cytomegalovirus infection

Murine cytomegalovirus (MCMV) infection of mice resulted in suppression of mitogen induced proliferation and interleukin 2 (IL-2) responses of splenic cells. This suppression was also evident as a reduction in the number of cells expressing Thy-1 or L3T4 and a reduction in the ratio of T helper/T suppressor cells. The pyrimidinone compound, bropirimine, when administered to MCMV infected mice was able to restore mitogen-induced proliferative and IL-2 responses of splenic cells, to increase the number of cells expressing Thy-1 or L3T4, to restore the ratio of T helper/T suppressor cells and to increase the number of cells inducible for expression of IL-2 receptors.