Measure Of Reserve Research Articles

Optimal Approaches for Measuring Tongue-Pressure Functional Reserve

Tongue-palate pressure is a parameter of considerable interest in the field of dysphagia. Maximum isometric tongue-palate pressures (MIPs) decline in healthy aging and in dysphagia. Functional reserve (FR) is the difference between MIPs and swallowing pressures. Reduced FR is thought to constitute a risk for developing functional swallowing impairments. We compare different approaches for calculating FR and recommend an optimal approach. Tongue-palate pressure data were collected from 78 healthy adults (40 < age 40; 38 > 60) during anterior and posterior MIPs, regular (RESS) and effortful (ESS) saliva swallows, and water swallows (4 repetitions per task). Six different measures of reserve were calculated using maximum anterior MIPs or ESS pressures at the top, and mean or maximum RESS or water swallow pressures at the bottom of the range. Correlations with age and MIPs were explored to confirm suitability for measuring FR. The impact of normalization to maximum MIP range was explored. We conclude that an optimal measure of FR involves the comparison of maximum MIP with mean saliva swallowing pressures. This parameter declines with age, but when normalized to an individual's MIP range, the relationship is no longer evident. This suggests that FR does not necessarily decline in healthy aging.

Reproducibility of rest and exercise stress contrast-enhanced calf perfusion magnetic resonance imaging in peripheral arterial disease.

BackgroundThe purpose was to determine the reproducibility and utility of rest, exercise, and perfusion reserve (PR) measures by contrast-enhanced (CE) calf perfusion magnetic resonance imaging (MRI) of the calf in normal subjects (NL) and patients with peripheral arterial disease (PAD).MethodsEleven PAD patients with claudication (ankle-brachial index 0.67 ±0.14) and 16 age-matched NL underwent symptom-limited CE-MRI using a pedal ergometer. Tissue perfusion and arterial input were measured at rest and peak exercise after injection of 0.1 mM/kg of gadolinium-diethylnetriamine pentaacetic acid (Gd-DTPA). Tissue function (TF) and arterial input function (AIF) measurements were made from the slope of time-intensity curves in muscle and artery, respectively, and normalized to proton density signal to correct for coil inhomogeneity. Perfusion index (PI) = TF/AIF. Perfusion reserve (PR) = exercise TF/ rest TF. Intraclass correlation coefficient (ICC) was calculated from 11 NL and 10 PAD with repeated MRI on a different day.ResultsResting TF was low in NL and PAD (mean ± SD 0.25 ± 0.18 vs 0.35 ± 0.71, p = 0.59) but reproducible (ICC 0.76). Exercise TF was higher in NL than PAD (5.5 ± 3.2 vs. 3.4 ± 1.6, p = 0.04). Perfusion reserve was similar between groups and highly variable (28.6 ± 19.8 vs. 42.6 ± 41.0, p = 0.26). Exercise TF and PI were reproducible measures (ICC 0.63 and 0.60, respectively).ConclusionAlthough rest measures are reproducible, they are quite low, do not distinguish NL from PAD, and lead to variability in perfusion reserve measures. Exercise TF and PI are the most reproducible MRI perfusion measures in PAD for use in clinical trials.

Comparison of fully quantitative and semi-quantitative measure of women's myocardial perfusion reserve for detection of microvascular coronary dysfunction

Background Myocardial perfusion reserve (MPR) acquired using firstpass cardiac MRI is a measure of the severity of microvascular coronary dysfunction (MCD) in subjects with signs and symptoms of ischemia but no obstructive coronary artery disease (CAD) [Shufelt 2011]. Semiquantitative measures (upslopes) have been used to analyze MPR data in the previous work [Shufelt 2011]. In this work, we propose using a fully quantitative myocardial blood flow (MBF) analysis to evaluate whether MPR is different between subjects with MCD and normal controls.

ART outcome in young women with premature ovarian aging.

Background:Young women with signs of ovarian aging are a matter of concern as far as their reproductive performance is concerned. With more women approaching infertility centers with this problem, it becomes necessary to understand what reproductive outcomes are possible in such cases. Female age and basal Follicle stimulating hormone (FSH) level, both are strong independent predictors of In Vitro Fertilization (IVF) outcome.Objective:To correlate age-related basal FSH with IVF outcome in women with premature ovarian aging in gonadotropins-induced cycles.Materials and Methods:Between January 2011 and October 2012, a total of 135 women undergoing IVF and ICSI cycles with antagonist protocol were included in this retrospective cohort study. Basal FSH concentrations were measured and the women's ages were calculated before they were undergoing pituitary desensitization and its correlation with assisted reproduction technique (ART) outcome was evaluated.Results:Increasing FSH was associated significantly with reduced number of oocytes retrieved, and embryos obtained. Young women with high FSH up to 20 produced less but good quality embryo's resulting in sound pregnancy rate.Conclusion:FSH is a quantitative and age is a qualitative measure of ovarian reserve. Both are equally important in predicting IVF outcome. Basal FSH concentration should be restricted to counseling of patients on probability of achieving pregnancy, but should not be used to exclude them from fertility treatment.

Comparison of passive leg raising and hyperemia on macrovascular and microvascular responses

Passive leg raising is a simple diagnostic maneuver that has been proposed as a measure of arterial vasodilator reserve and possibly endothelial function. While passive leg raising has previously been shown to lower blood pressure, increase flow velocity and cause brachial artery dilation, its effects on microvascular flow has not been well studied. Also, passive leg raising has been directly compared previously to upper arm but never to lower arm occlusion of blood flow induced hyperemia responses. We compared changes in macrovascular indices measured by brachial artery ultrasound and microvascular perfusion measured by Laser Doppler Flowmetry induced by passive leg raising to those provoked by upper arm and lower arm induced hyperemia in healthy subjects. Upper arm induced hyperemia increased mean flow velocity by 398%, induced brachial artery dilatation by 16.3%, and increased microvascular perfusion by 246% (p<.05 for all). Lower arm induced hyperemia increased flow velocity by 227%, induced brachial artery dilatation by 10.8%, and increased microvascular perfusion by 281%. Passive leg raising increased flow velocity by 29% and brachial artery dilatation by 5.6% (p<.05 for all), but did not change microvascular perfusion (−5%, p=ns). In conclusion, passive leg raising increases flow velocity orders of magnitude less than does upper arm or lower arm induced hyperemia. Passive leg raising-induced brachial artery dilatation is less robust than either of these hyperemic techniques. Finally, although upper arm and lower arm hyperemia elicits macrovascular and microvascular responses, passive leg raising elicits only macrovascular responses.

MRI for the assessment of organ perfusion in patients with chronic kidney disease

Recent data have highlighted the importance of quantitative measures of organ perfusion and functional reserve. Magnetic resonance imaging allows the assessment of markers of perfusion without the use of contrast media. Techniques such as arterial spin labelling (ASL) and blood oxygen level-dependent (BOLD) imaging have been available for some time, but advances in the technology and concerns over the safety of contrast media in renal disease have spurred renewed interest and development. ASL measures perfusion, whereas BOLD imaging provides a marker of blood oxygenation, arising from the compound effect of a number of measures including perfusion, blood volume and oxygen consumption; thus, the techniques are complementary rather than analogous. They were initially confined to brain imaging as inherently low signal, susceptibility effects and motion limited their use in thoracic and abdominal organs. Advances in technology have led to robust sequences that can quantify clinically relevant changes and correlate well with reference standards. Novel approaches are likely to accelerate translation into clinical practice. The noninvasive and repeatable nature of ASL and BOLD imaging makes it likely that they will be increasingly used in clinical research. Using a developmental framework, we suggest that the application of these techniques to thoracic and abdominal organs requires validation before they are suitable for generalized clinical use. The demand for these techniques is likely to be driven by the incentive to avoid the use of contrast media.

Testing and interpreting measures of ovarian reserve: a committee opinion

Currently, there is no uniformly accepted definition of decreased ovarian reserve (DOR), as the term may refer to three related but distinctly different outcomes: oocyte quality, oocyte quantity, or reproductive potential. Available evidence concerning the performance of ovarian reserve tests is limited by small sample sizes, heterogeneity among study design, analyses and outcomes, and the lack of validated outcome measures.

Pretreatment antimüllerian hormone levels determine rate of posttherapy ovarian reserve recovery: acute changes in ovarian reserve during and after chemotherapy

To identify factors associated with ovarian reserve impairment during and immediately after chemotherapy. Prospective cohort study. Four university hospitals. Forty-six adolescent and young adult women with a new diagnosis of cancer requiring chemotherapy. None. Measurements of ovarian reserve via levels of serum follicle-stimulating hormone, luteinizing hormone, estradiol, inhibin B, and antimüllerian hormone (AMH) as well as antral follicle counts and mean ovarian volume at 3-month intervals. Changes in ovarian reserve were quantified for both the acute impact of treatment using linear regression and the longitudinal recovery after therapy using mixed-effects models adjusted for baseline ovarian reserve, use of alkylating agent, and hormone use. The women had at least one pretreatment and two posttreatment study visits (mean follow-up interval: 12 months). All measures of ovarian reserve demonstrated statistically significant changes during chemotherapy. Alkylating agent exposure and baseline ovarian reserve were acutely associated with the magnitude of impairment, and pretreatment AMH levels were associated with the rate of recovery of AMH after treatment. In adjusted models, participants with a pretreatment AMH level > 2 ng/mL recovered at a rate of 11.9% per month after chemotherapy, whereas participants with pretreatment AMH levels ≤ 2 ng/mL recovered at a rate of 2.6% per month after therapy. Baseline ovarian reserve and alkylating agent exposure effect the magnitude of acute changes in ovarian reserve from chemotherapy. The rate of recovery of AMH is impacted by pretreatment levels. This should be considered during pretreatment fertility preservation counseling.

Anti-mullerian hormone (AMH) is diminished in female lymphoma patients even before oncological treatment

Oncologic diseases present unique challenges for fertility preservation. There is some evidence that response to ovarian stimulation is impaired in patients with a new cancer diagnosis even before cancer therapy. However there is little data measuring early follicular phase hormones in this population. The aim of this study was to assess measures of ovarian reserve in female cancer patients before cancer therapy is initiated.

Young cancer survivors achieve unassisted pregnancies at a rate similar to healthy controls despite impaired measures of ovarian reserve

of Dundee Drug Discovery Unit library collections. Changes in fluorescence were measured using the FlexStation 3. RESULTS: Progesterone elicited a reproducible concentration dependent increase in [Ca]i with a calculated pEC50 of 6.9. A z’ value of >0.5 was routinely calculated for the assay using a maximally active concentration of progesterone (10mM). CONCLUSION: Following initial screening of a focussed ion channel compound library, a number of novel compounds were identified, with similar activity to progesterone, and now the subject of further evaluation. This may hold therapeutic options for male fertility. Supported by: This study was funded by Tenovus Scotland.

Susceptibility to Distraction During Reading in Young, Young-Old, and Old-Old Adults

Background/Study Context: Susceptibility to distraction during reading may increase with age, resulting in comprehension errors. Neurological integrity and cognitive reserve are possible covariates of age-related distraction susceptibility. The current study investigated distraction susceptibility in three age groups (young, young-old, and old-old), and examined the covariation patterns of variable sets associated with neurological integrity and cognitive reserve. Methods: Participants responded to comprehension questions after reading stories that included semantically related or semantically unrelated distractors. Neurological integrity measures consisted of Mini-Mental State Examination, Selective Reminding, and Category Fluency. Cognitive reserve measures consisted of education and vocabulary. Results: Old-old adults were more likely than young and young-old adults to select distractors when responding to comprehension questions (24.02%, 11.95%, 3.68%, respectively). Age-related distraction variance significantly overlapped neurological variance, and became more transparent after cognitive reserve variance was controlled. Conclusion: This study augments previous age-related distraction research by highlighting (a) the increase in distraction susceptibility in adults over 79, particularly when distractors are semantically related; (b) the influence of age-related neurological integrity on distraction; and (c) the possibility that education and verbal experience may decrease distraction susceptibility, consistent with cognitive reserve frameworks.

Comparación entre ancianos sanos con alta y baja reserva cognitiva y ancianos con deterioro cognitivo

Este trabajo presenta la comparación de las características de sujetos con alta y baja reserva cognitiva, y sujetos con baja reserva cognitiva y deterioro cognitivo, diferenciados a partir del desarrollo de una medida ponderada de reserva cognitiva. Mediante un diseño correlacional se evaluaron 200 personas con edad superior a 65 años, no institucionalizados. Los resultados mostraron, por un lado, que el grupo de alta reserva cognitiva obtuvo mejores puntuaciones tanto en el nivel de deterioro cognitivo como en la medida ponderada de reserva que el grupo de baja reserva cognitiva y, por otro lado, el grupo de baja reserva cognitiva mostró un perfil similar al del grupo de deterioro cognitivo, existiendo solamente diferencias en cuanto a la edad. Las diferencias observadas permiten plantear la medida como una variable que se debe tener en cuenta en el diagnóstico de enfermedades neurodegenerativas y su utilidad para establecer posibles tratamientos.

Quantification of anti-Mullerian hormone (AMH) in dried blood spots: validation of a minimally invasive method for assessing ovarian reserve

Biological markers of ovarian reserve have the potential to advance research on fecundability, infertility and reproductive aging. Anti-Müllerian hormone (AMH) has emerged as a clinically useful measure of ovarian reserve, but the requirement for venous blood is an obstacle to application in non-clinical settings. This paper validates a new method for quantifying AMH in dried blood spot (DBS) samples--drops of whole blood collected on filter paper following a simple finger stick. Matched serum and DBS samples were obtained from n=101 women of reproductive age, and AMH values were compared using regression analyses and scatter plots. The precision, reliability, linearity, recovery and lower detection limit of the DBS assay were evaluated, as well as the stability of AMH in DBS across a range of storage conditions. There was a strong agreement between AMH concentrations measured in DBS and serum samples across the entire assay range. Analysis of within-assay (percent coefficient of variation, 4.7-6.5%) and between-assay (3.5-7.2%) variability indicated a high level of assay precision and reliability, respectively. The minimum detectable dose of AMH was 0.065 ng/ml. Concentrations of AMH remained stable in DBS samples stored for 2 weeks at room temperature, and for 4 weeks when refrigerated. The DBS assay performs at a level that is comparable to serum-based methods, with the advantage of lower burdens and costs associated with blood collection that may be advantageous for research in clinical as well as non-clinical settings on the causes and consequences of variation in ovarian reserve.

Cognitive reserve and patient-reported outcomes in multiple sclerosis

Background: Adaptation and compensation in the face of changing pathology may be better understood by considering the concept of cognitive reserve, which may protect against disability in multiple sclerosis (MS). Objectives: The present work investigates the relationship between cognitive reserve and demographic characteristics, health behaviors, and patient-reported outcomes (PROs). Methods: Cross-sectional data (n=1142) were drawn from the North American Research Committee on MS (NARCOMS) Registry, from whom additional survey data were collected. Cognitive reserve was measured using the Stern and Sole-Padulles measures, the O*NET occupational classification system, and the Godin Leisure-Time Exercise Questionnaire. PROs were assessed using generic (SF -12v2, Perceived Deficits Questionnaire, Ryff Psychological Well-Being, Diener Satisfaction with Life Scale) and disease-specific (Patient-Determined Disease Steps, Performance Scales) measures. Psychometric analysis created unidimensional cognitive reserve subscales. Regression models examined relationships between cognitive reserve, demographic characteristics, and PROs. Results: The cognitive reserve measures assessed distinct but related constructs. Individuals with high cognitive reserve were more likely to report lower levels of perceived disability and perceived cognitive deficits, and higher levels of physical health, mental health, and well-being. Both active and passive reserve are associated with better outcomes, independent of demographic factors, and these associations apply to both generic and disease-specific outcomes. Conclusions: This expanded measurement of cognitive reserve captures both the passive and active aspects of the construct, and there is a consistent and substantial relationship with PROs. Individuals with high passive and/or active reserve are healthier and experience higher levels of well-being.

Objective Measures of Physical Functional Capacity Warrant Exploration to Complement or Replace the Subjective Physician Estimated Performance Status

Performance status, a measure of physical functioning, can be influenced by several undefined physician and patient-related factors, and is inherently subjective. Although disappointing results in phase 3 trials may reflect a lack of improved outcomes due to biological mechanisms, a confounding effect of imbalances of physical functioning cannot be excluded in the context of modest increments in antitumor activity. Therefore, performance status estimation may complicate drug development, and an objective measure of physical reserve is desirable and may complement or outperform performance status. We explore and discuss attractive candidates for objective measures of physical functioning.

MRI of Arterial Flow Reserve in Patients with Intermittent Claudication: Feasibility and Initial Experience

ObjectivesThe aim of this work was to develop a MRI method to determine arterial flow reserve in patients with intermittent claudication and to investigate whether this method can discriminate between patients and healthy control subjects.MethodsTen consecutive patients with intermittent claudication and 10 healthy control subjects were included. All subjects underwent vector cardiography triggered quantitative 2D cine MR phase-contrast imaging to obtain flow waveforms of the popliteal artery at rest and during reactive hyperemia. Resting flow, maximum hyperemic flow and absolute flow reserve were determined and compared between the two groups by two independent MRI readers. Also, interreader reproducibility of flow measures was reported.ResultsResting flow was lower in patients compared to controls (4.9±1.6 and 11.1±3.2 mL/s in patients and controls, respectively (p<0.01)). Maximum hyperemic flow was 7.3±2.9 and 16.4±3.2 mL/s (p<0.01) and the absolute flow reserve was 2.4±1.6 and 5.3±1.3 mL/s (p<0.01), respectively in patients and controls. The interreader coefficient of variation was below 10% for all measures in both patients and controls.ConclusionsQuantitative 2D MR cine phase-contrast imaging is a promising method to determine flow reserve measures in patients with peripheral arterial disease and can be helpful to discriminate patients with intermittent claudication from healthy controls.

Determinants and Functional Significance of Myocardial Perfusion Reserve in Severe Aortic Stenosis

The purpose of this study was to assess the functional significance of cardiac magnetic resonance (CMR) measures of left ventricular (LV) remodeling and myocardial perfusion reserve (MPR) in patients with severe aortic stenosis (AS), without obstructive coronary artery disease. Measures of stenosis severity do not correlate well with exercise intolerance in AS. LV remodeling in AS is associated with myocardial fibrosis and impaired MPR. The functional significance and determinants of MPR in AS are unclear. Forty-six patients with isolated severe AS were prospectively studied before aortic valve replacement. The following investigations were undertaken: cardiopulmonary exercise testing to measure aerobic exercise capacity (peak VO(2)); CMR to assess left ventricular mass index (LVMI), myocardial fibrosis with late gadolinium enhancement (LGE), myocardial blood flow (MBF), and MPR; and transthoracic echocardiography to assess stenosis severity and diastolic function. Peak VO(2) was associated with sex (β = -0.41), age (β = -0.32), MPR (β = 0.45), resting MBF (β = -0.53), and septal transmitral flow velocity to annular velocity ratio (E/E') (β = -0.34), but not with LVMI, LGE, or echocardiographic measures of AS severity. On stepwise regression analysis, only MPR was independently associated with age- and sex-corrected peak VO(2) (β = 0.46, p = 0.001). MPR was also inversely related to New York Heart Association functional class (p = 0.001). Univariate associations with MPR were sex (β = 0.38, p = 0.02), septal E/E' (β = -0.30, p = 0.03), peak aortic valve velocity (β = -0.34, p = 0.02), LVMI (β = -0.51, p < 0.001), and LGE category (β = -0.46, p = 0.002). On multivariate analysis, LVMI and LGE were independently associated with MPR. CMR-quantified MPR is independently associated with aerobic exercise capacity in severe AS. LV remodeling appears to be a more important determinant of impaired MPR than stenosis severity per se. Further work is required to determine how CMR assessment of MPR can aid clinical management of patients with AS.

Anti-Mullerian hormone: clairvoyance or crystal clear?

The clinical use of anti-Müllerian hormone (AMH) has increased exponentially due to its unique relationship with the ovarian reserve and ability to predict ovarian response, facilitate pretreatment counselling and individualize treatment strategies to minimize the risk of ovarian hyperstimulation syndrome. There is now a rapidly increasing literature examining additional possibilities for AMH, all of which suggest that its reach extends far beyond the assisted conception clinic. The recognition that it is a significantly more accurate and reliable measure of ovarian reserve than the antral follicle count or FSH has led to its adoption by physicians to counsel women on their reproductive lifespan, the impact of gonadotoxic chemotherapy, radiotherapy and surgery on the ovarian reserve and allow polycystic ovarian syndrome to be diagnosed by primary care physicians. We propose that there is an adequate literature base to embrace this technology while continuing to develop and refine how AMH can optimize patient care.

Ovarian Volume Correlates Strongly with the Number of Nongrowing Follicles in the Human Ovary

A reliable indirect measure of ovarian reserve for the individual woman remains a challenge for reproductive specialists. Using descriptive statistics from a large-scale study of ovarian volumes, we have developed a normative model for healthy females for ages 25 through 85. For average values, this model has a strong and positive correlation (r = 0.89) with our recent model of nongrowing follicles (NGFs) in the human ovary for ages 25 through 51. When both models are log-adjusted, the correlation increases to r = 0.99, over the full range of ovarian volume. Furthermore we can deduce that an ovary of 3 cm3 volume (or less) contains approximately 1000 NGF (or fewer). These strong correlations indicate that ovarian volume is a useful factor in the indirect estimation of human ovarian reserve for the individual woman.

Cerebral blood flow and neuropsychological functioning in elderly vascular disease patients

This study was designed to determine the relationships between positron emission tomography (PET)-based quantitative measures of cerebral blood flow and cerebrovascular reserve and neuropsychological functioning in elderly individuals with atherosclerotic vascular disease. It was hypothesized that cerebrovascular function would be significantly associated with neuropsychological functioning. Results showed that both baseline global cerebral blood flow and cerebrovascular reserve were significantly associated with global neuropsychological functioning, when controlling for age and sex. Cerebrovascular reserve was additionally associated with performance on measures of memory and attention. Additional research is needed to determine whether measures of cerebral blood flow can be used to predict cognitive decline.