Biomedical subjects

Clifford Qualls

Publications and source records attributed to Clifford Qualls.

At least 19 recordsLinked to original sources

PubMed2006

Estimating absolute glomerular filtration rate in children.

Normal values of glomerular filtration rate (GFR) in children are often expressed in a value adjusted to adult ideal body surface area. These values work well for many clinical situations, but in infants and children, especially those with atypical body mass, they may not accurately reflect renal function. Most body composition values in children are expressed in developmentally appropriate ranges. Absolute GFR (ml/min) also changes during childhood increasing rapidly in infancy and then gradually with age and body size. Previously, we developed a bedside equation for estimating GFR (ml/min) in children that accounted for changes with age and body size, and which correlated well with steady-state cold iothalamate GFR (ml/min) measurements: GFR (ml/min) = k(*)sqrt[(age(months) + 6)*wt (kg)/serum Cr (mg/dl)], where k=0.95 for females and 1.05 for males. In the present study GFR (ml/min) measured by iothalamate infusion was compared by correlation analysis with estimates calculated from the above equation in 566 children. This equation provides clinicians with a simple bedside method to estimate absolute GFR (ml/min).

Adolescent↗

PubMed2006

Conformity with current guidelines on oral contraceptive prescribing for breastfeeding women: a New Mexico survey.

BACKGROUND: National and international contraceptive guidelines reflect expert opinion that recommends against the use of estrogen-containing hormonal contraception in the early postpartum period. This study was undertaken to estimate providers' practices in prescribing hormonal contraception to breastfeeding women. METHODS: A 19-item survey was mailed to 397 obstetrician gynecologists, midwives and family physicians in the state of New Mexico. The survey included items covering attitudes about the impact of hormonal contraception on breastfeeding and prescribing practices. One hundred ninety-nine (50%) providers completed the survey. RESULTS: The majority (70%) of providers prescribe progestin-only contraceptive methods to breastfeeding women within the first 6 weeks. Despite these recommendations, a sizable minority of providers prescribe combined pills in the early postpartum period: 27% of providers have prescribed combined pills and 13% of providers, mostly those in a university setting, routinely recommend them within the first 6 weeks postpartum. CONCLUSION: Most providers follow expert recommendations regarding the initiation of hormonal contraception for breastfeeding women.

Adult↗

PubMed2006

Aging: compensation or maturation?

Neuroimaging studies of healthy aging often reveal differences in neural activation patterns between young and elderly groups for episodic memory tasks, even though there are no differences in behavioral performance. One explanation typically offered is that the elderly compensate for their memory deficiencies through the recruitment of additional prefrontal regions. The present study of healthy aging compared magnetoencephalographic (MEG) time-courses localized to specific cortical regions in two groups of subjects (20-29 years and >or=65 years) during a visual delayed-match-to-sample (DMS) task. MR morphometrics and neuropsychological test results were also examined with the hope of providing insight into the nature of the age-related differences. The behavioral results indicated no differences in performance between young and elderly groups. Although there was a main effect of age on the latency of the initial peak in primary/secondary visual cortex, these longer latencies were not correlated with the performance of elderly on the DMS task. The lateral occipital gyrus (LOG) revealed qualitatively different patterns of activity for the two age groups corroborated by neuropsychological test results. Morphometric results for the young versus elderly groups revealed less white (WM) and gray matter (GM) volumes in the frontal lobes of the elderly. When a group of middle-aged subjects (33-43 years) was included in the morphometric analyses, the middle-aged subjects revealed statistically greater WM volumes in frontal and parietal cortex suggesting immature WM tracts in the young. Perhaps our elderly utilized a different strategy compared to the young due to the different brain maturation levels of these groups.

Adult↗

PubMed2006

Cerebral vasodilatation to exogenous NO is a measure of fitness for life at altitude.

BACKGROUND AND PURPOSE: Andean highlanders, unlike Ethiopians, develop chronic mountain sickness (CMS), a maladaptation to their native land. Ambient hypoxia induces NO-mediated vasodilatation. Fitness for life at altitude might be revealed by cerebrovascular responses to NO. METHODS: Nine altitude-native men were examined at 3622 and 794 m in Ethiopia and compared with 9 altitude-native Andean men tested at 4338 and 150 m in Peru. We assessed CMS scores, hematocrits, end-tidal pressure of carbon dioxide (P(ET)co2), oxygen saturations, and cerebral blood flow velocity (CBV). We evaluated fitness for life at altitude from the cerebrovascular response to an exogenous NO donor. RESULTS: At high altitude, CMS scores and hematocrits were higher in Andeans, and they had lower oxygen saturations. Ethiopians had higher P(ET)co2 at all study sites. At low altitude, saturations were similar in both groups. Responsiveness of the cerebral circulation to NO was minimal in Ethiopians at low altitude, whereas Andeans had a large response. In contrast, at high altitude, Ethiopians showed large responses, and Peruvians had minimal responses. CONCLUSIONS: By our measure, high altitude-native Peruvians were well-adapted lowlanders, whereas Ethiopian highlanders were well adapted to altitude life. Environmental pressures were sufficient for human adaptation to chronic hypoxia in Africa but not South America. The mechanisms underlying these differences are unknown, although studies of neurovascular diseases suggest that this may be related to a NO receptor polymorphism.

Acclimatization↗

PubMed2006

Chronic hypoxia in Andeans; are there lessons for neurology at sea level?

Hypoxia is implicated in aging and neurodegenerative diseases. We posited that changes in gene expression induced by ambient hypoxia at altitude may be neuroprotective to natives of these regions. We studied 30 men. Twenty natives of Cerro de Pasco (CP), altitude 4,338 m were examined in CP; then transported within 6 h to Lima (150 m-sea level) and examined 1 h after arrival. They were assessed by a Chronic Mountain Sickness-score (CMS-sc) in CP, 10 were normal Andeans and 10 had chronic mountain sickness (CMS), a sudden inexplicable loss of adaptation to their native environment. RNA was extracted from venous blood white cells. The Andeans were compared to 10 normal US men living at 1500 m using RT-PCR. We focused on the cyto-neuro-protective genes, Ataxia telangiectasia mutated (ATM), heme-oxygenase-1 (HMOX 1), heat shock protein-70 (HSP-70), heat shock protein-90 (HSP-90), and the neuroprotective enzyme, nicotinamide mononucleotide adenylyl transferase 1 (Nnmat 1). CMS patients had significantly higher levels of gene expression (HMOX-1, HSP-70, ATM) than Andean controls in CP. HSP-90 and Nmnat 1, however, were higher in Andean controls in all locations. Significant reductions of all gene products, within an hour of arriving in normoxia in Lima, were found. In Andean controls, the gene products in Lima fell to levels approaching US controls. Correlation and regression methods showed men with high expression of all gene products had an average CMS-sc=19.8; those with low expression a normal score (9.4, P=0.02). ATM expression was related to age (P<0.001). The natural experiment that unfolds in the mountainous regions of the world provides opportunities to study neuroprotection in intact humans.

Adaptation, Physiological↗

PubMed2006

Gene expression, autonomic function and chronic hypoxia:lessons from the Andes.

Autonomic function is altered by altitude in sojourners and natives. We hypothesized that these physiologic responses are modulated by changes in gene expression. We compared gene product levels in 20 natives of Cerro de Pasco (CP), (4338 m), 10 of which had chronic mountain sickness (CMS) established by a CMS-scoring system, with gene products in the same men after 1 h at sea level. We further compared the results with those obtained from 10 US men residing at 1500 m. We measured gene products in white cells by reverse transcription polymerase chain reaction (RT-PCR). We focused on genes important in vascular autonomic physiology, and/or activated by hypoxia; hypoxia inducible factor 1-alpha (HIF 1-alpha), 2 splicing variants of vascular endothelial growth factor (VEGF); VEGF-121, VEGF-165, and phosphoglycerate kinase 1 (PGK 1). Normal CP natives showed high expression of all genes in CP, compared to US controls. Within 1 h of arrival at sea level, they had comparable levels to US residents. In CMS, the gene products were higher in CP. Although gene products decreased in Lima in this group, they never reached US values. VEGF 121 and 165 were correlated (P<0.001). VEGF 165 was higher in CMS in CP (P=0.006), and was positively correlated with CMS-score (R=0.86, P<0.001), and negatively correlated with arterial saturation (R=-0.79, P<0.001). Our findings underscore the changes in gene expression levels in intact humans in response to environmental stress. These changes may support the physiologic alterations induced by the ambient hypoxia at altitude and impact organism survival. They also suggest therapeutic strategies for autonomic and neurodegenerative diseases at sea level.

Adaptation, Physiological↗

PubMed2006

A comparison of periurethral blood flow resistive indices and urethral closure pressure of incontinent women.

This study correlated Doppler resistive indices (RIs) with maximum urethral closure pressures (MUCPs) in women with stress urinary incontinence. We hypothesized that urethral blood flow would be inversely correlated to urethral closure pressures. Fifty-three women underwent spectral Doppler waveform analyses of periurethral vasculature to calculate RI. Urethral morphology including pubovesicular length (PVL) with and without cough was measured. MUCPs were obtained according to International Continence Society guidelines. Physical exam and history were also obtained. Correlation coefficients were calculated for comparisons of Doppler measurements and closure pressures. Fifty patients were required to detect a difference between no correlation and a modest correlation of 0.38 with 80% power and alpha of 0.05. Significance is set at p<0.05. Measurements were reproducible between Doppler waveforms and MUCP measurements (all p=NS). RI was not correlated with age, parity, MUCP, Incontinence Impact Questionnaire-7 scores, urethral length, or urethral width (all p=NS). RI and MUCP were likewise not associated with history of diabetes, hypertension, or anterior vaginal prolapse to or beyond the hymen (all p=NS). MUCP was negatively correlated with age (r=-0.33, p=0.01) even when controlled for hormonal status (ANCOVA, p=0.003) and positively correlated with urethral/bladder neck diameter (r=27, p=0.05), PVL (r=0.30, p=0.03), and PVL with cough (r=0.36, p=0.009).

Female↗

PubMed2006

Does sexual function change after surgery for stress urinary incontinence and/or pelvic organ prolapse? A multicenter prospective study.

OBJECTIVE: The purpose of this study was to assess sexual function in women after surgery for stress urinary incontinence and/or pelvic organ prolapse (UI/POP) at 3 and 6 months with the Pelvic Organ Prolapse Urinary Incontinence Sexual Questionnaire (PISQ). STUDY DESIGN: Of 269 eligible women participating in a trial of prophylactic antibiotic use with suprapubic catheters, 102 (37.9%) agreed to participate in a sexual function study. Women underwent a variety of anti-incontinence and reconstructive surgeries. Sexual function and urinary incontinence were assessed preoperatively and at 3 and 6 months, postoperatively, with the PISQ and Incontinence Impact Questionnaires (IIQ-7). Paired t tests compared changes over time. Logistic regression compared worsening PISQ versus other variables. Generalized McNemar test compared individual questions preoperatively and postoperatively. Significance was set at P < .05. RESULTS: Mean age was 47.1 (23-85) years, and 64% of women were premenopausal. Seventy-five (74%) women completed questionnaires at 3 or 6 months. Sexual function scores improved after surgery as did IIQ-7 scores (PISQ 89 vs 95, P < .001; IIQ-7 = 52 vs 13, P < .001). The Behavioral Emotive domain scores did not change at 3 to 6 months compared with preoperative scores P = .57), whereas the Physical domain improved (P < .001). Worsening PISQ scores were independent of age, type of surgery, hysterectomy, complications, or hormonal status (logistic regression, all P < .05). CONCLUSION: Sexual function scores in women improve after surgery for UI/POP as did improvement of incontinence at 3 to 6 months after surgery.

Adult↗

PubMed2006

Relationship between central corneal thickness and severity of glaucomatous visual field loss in a primary care population.

BACKGROUND: Although the ability of central corneal thickness (CCT) to predict development of primary open-angle glaucoma has become increasingly well recognized, the ability of CCT to predict severity of glaucoma remains uncertain. This study was designed to expand the available knowledge about the relationship between CCT and glaucoma severity. METHODS: Retrospective identification of all patients with a clinical diagnosis of either primary open angle glaucoma (POAG) or ocular hypertension who were seen from September 2002 through May 2003 at the Albuquerque VA Medical Center eye clinic was completed. Eligible subjects were segregated into no, mild, moderate, or advanced visual field loss groups based on Advanced Glaucoma Intervention Study (AGIS) visual field scoring criteria. Following statistical analyses comparing the visual field groups, the sample was divided into thin, intermediate, and thick CCT groups, and further analysis was performed. RESULTS: Mean CCT was significantly higher in the no field loss group compared with all 3 groups with glaucomatous visual field loss. Mean CCT was not statistically different, however, between the mild, moderate, and advanced visual field loss groups. In linear regression analyses, no significant relationship was found between CCT and severity of visual field loss. CONCLUSIONS: Although CCT was associated strongly with development of POAG-related visual field loss, CCT was not associated with severity of visual field loss in this study. These findings suggest that glaucoma patients with thinner corneas are just as likely to have advanced levels of field loss as glaucoma patients with thicker corneas. Prospective studies are needed to validate these findings.

Aged↗

PubMed2006

Central corneal thickness and normal tension glaucoma: a cross-sectional study.

BACKGROUND: Recently published evidence has identified thinner central corneal thickness (CCT) as a strong predictive factor for the conversion from ocular hypertension (OHT) to primary open-angle glaucoma (POAG). The association between CCT and development of normal-tension glaucoma (NTG), however, is less clear. Accordingly, we designed this cross-sectional study to further explore the relationship between CCT and NTG. PATIENTS AND METHODS: All patients with a clinical diagnosis of NTG and NTG suspect (NTGS) who were seen from September 2002 through May 2003 at the Albuquerque VA Medical Center eye clinic were identified retrospectively. After eligible subjects were categorized into no, mild, moderate, and advanced visual field loss groups, analysis of variance (ANOVA) and regression analyses were used to determine group differences for several IOP variables, several systemic variables, and CCT. Additional analyses were completed after eligible subjects were recategorized into thin, intermediate, and thick CCT groups. RESULTS: Eighty-four eyes in 84 NTGS subjects and 56 eyes in 56 NTG subjects were studied. Mean CCT was significantly thicker in the no field loss group (NTGS) when compared with all 3 groups with glaucomatous visual field loss (NTG). In multivariate regression analysis, the association between CCT and the presence of NTG-related visual field loss was robust and independent. Conversely, no relationship was found between CCT and severity of NTG-related visual field loss. CONCLUSIONS: In eyes characterized by statistically normal intraocular pressure (IOP) measurements as measured by Goldmann applanation tonometry, we found a significant relationship between CCT and the presence, but not severity, of glaucomatous visual field loss. A prospective study is required to further explore and confirm these relationships.

Aged↗

PubMed2006

Abrupt discontinuation of alprazolam and cognitive style in patients with panic disorder: early effects on mood, performance, and vital signs.

The objective of this study was to ascertain the relationship of alprazolam plasma levels and an anxiety-prone cognitive style to the characteristics and severity of early withdrawal after abrupt discontinuation of alprazolam in 26 patients with panic disorder. After 8 and 9 weeks of fixed-dose treatment, patients were hospitalized for 24 hours. On 1 admission, ordered at random, treatment was maintained; on the other, placebo was substituted double blind. The Anxious Thoughts and Tendencies questionnaire was administered before treatment. Alprazolam plasma levels were measured 7 times on the day after each admission. Before each blood sampling, the Profile of Mood States and performance tasks were administered, and vital signs were recorded. On the day after abrupt discontinuation of alprazolam, Profile of Mood States anxiety, depression, fatigue, and confusion increased; vigor and elation decreased; speed on the digit symbol substitution task improved; and systolic blood pressure increased substantially over time. High Anxious Thoughts and Tendencies scores were related specifically to more anxiety. Our findings (1) confirm that dysphoric mood, fatigue, low energy, confusion, and elevated systolic blood pressure are part of the early syndrome of withdrawal from alprazolam in patients with panic disorder, notably as the drop in plasma levels approaches 50%; (2) indicate a psychomotor deficit persisting beyond dose stabilization; (3) suggest that an anxiety-prone cognitive style measurable before undertaking treatment may be a risk factor for more severe anxiety upon discontinuation; and (4) provide a rationale for applying cognitive behavior therapy during benzodiazepine taper.

Adolescent↗

PubMed2006

Relationship between asymmetric central corneal thickness and glaucomatous visual field loss within the same patient.

PURPOSE: Considering that thinner central corneal thickness (CCT) has been identified as a significant glaucoma risk factor, this study was designed to determine whether patients with glaucoma with asymmetric CCT demonstrate greater visual field loss in their thinner CCT eye compared with their thicker CCT eye. METHODS: Patient logs were used to retrospectively identify patients with primary open-angle glaucoma (POAG) and patients with normal-tension glaucoma (NTG) with CCT asymmetry of 10 microm or greater. Severity of glaucoma was determined using Advanced Glaucoma Intervention Study (AGIS) visual field scoring criteria. After statistical analysis was used to compare all thinner CCT eyes vs. corresponding thicker CCT eyes, subjects with worse visual field loss in the thinner CCT eye were compared with subjects with worse visual field loss in the thicker CCT eye. Subanalysis was then completed using only subjects with CCT asymmetry of 15 microm or greater. RESULTS: In the 52 subjects who met all criteria for study inclusion, mean AGIS score was significantly higher in the thinner CCT eyes compared with the thicker CCT eyes. Subjects with higher AGIS score in their thinner CCT eye outnumbered subjects with higher AGIS score in their thicker CCT eye, with the differences approaching statistical significance in the full sample (p = 0.06) and achieving significance when analysis was limited to subjects with CCT asymmetry of 15 microm or greater (p = 0.001). Multivariate logistic regression analysis identified thinner CCT as the primary risk factor associated with higher AGIS score in subjects with CCT asymmetry of 15 microm or greater. CONCLUSION: These results correspond to prior reports implicating CCT as an independent risk factor for glaucomatous visual field loss. When significant CCT asymmetry is present in patients with glaucoma, the thinner CCT eye is at greater risk for more advanced visual field loss. The underlying nature of this increased risk is unknown, but further study into structural vulnerabilities associated with thinner CCT seems justified.

Aged↗

PubMed2006

The Trauma Symptom Inventory: factors associated with invalid profiles in a sample of combat veterans with post-traumatic stress disorder.

The assessment of combat-related post-traumatic stress disorder (PTSD) relies upon self-reported symptoms and the need for indicators of valid reporting is critical. The Trauma Symptom Inventory (TSI) is a testing instrument specific to PTSD which includes validity scales. In a pilot study examining the use of the TSI with combat veterans, 50 male veterans diagnosed with PTSD were administered the TSI. Nineteen percent of the profiles were invalid, all but one based on the Atypical Response Scale. Differences between veterans with valid and invalid TSI profiles are examined in terms of demographic and historical factors, TSI profiles, and individual scale items. The model best able to predict invalid profiles included high scores on subscales measuring dissociative experiences and tension reduction behaviors. Implications for the interpretation of TSI validity scales in assessing combat-related PTSD are discussed.

Adult↗

PubMed2005

Age-related effects on superior temporal gyrus activity during an auditory oddball task.

We used magnetoencephalography in combination with magnetic resonance imaging to investigate the effects of aging on the temporal dynamics of activity localized to several brain regions during an auditory oddball task. The most interesting effects were noted in the superior temporal gyrus as follows: (1) responses were generally stronger to rare than to frequent tones throughout the entire 600-ms time interval, and (2) increases in the amplitude of the 40-ms peak and the latency of the maximum late response were evident in the elderly. Although superior temporal gyrus activity has traditionally been associated with early sensory processing, these results suggest that superior temporal gyrus activity is also important for later decision-related processing.

Acoustic Stimulation↗

PubMed2005

Temporal dynamics of age-related differences in auditory incidental verbal learning.

Auditory response profiles for a group of ten healthy young and ten healthy elderly subjects, evoked by implicit memory and delayed verbal recognition tasks, were evaluated to determine if effects of stimulus repetition could be identified in the superior temporal gyrus (STG) and prefrontal cortical regions. We hypothesized that effects of stimulus repetition should occur both early in time and at early levels of the nervous system (STG) followed by later effects in prefrontal regions. Magnetoencephalographic (MEG) responses were recorded using a whole-head MEG system and automated, multi-start analysis methods were applied to the data in order to characterize the temporal response profiles from distributed but focal, cortical regions engaged in memory-related tasks. The findings revealed a main effect of age for early activity ( approximately 50 ms) in STG which appeared to be nonspecific for Old/New words and an Age x Task interaction for late activity ( approximately 100-800 ms) in STG which was specific to Old/New words. Although the behavioral performance measures did not reveal traditional effects of response priming, the MEG measures did reveal a reduction in amplitude with stimulus repetition in young subjects. The elderly did not reveal a reduction in amplitude concomitant with stimulus repetition for either the global attributes of words or for specific Old/New words. Long duration effects of stimulus repetition noted in the present study raise the possibility that results from sensory gating, mismatch negativity and P300 paradigms may represent a continuum of stimulus repetition effects. Two of these paradigms evoke greater enhancement to novel or infrequent stimuli, or rather, greater reduction of amplitude with repetition.

Adult↗

PubMed2005

Characterization of a spatial gradient of nitrogen dioxide across a United States-Mexico border city during winter.

A gradient of ambient nitrogen dioxide (NO(2)) concentration is demonstrated across metropolitan El Paso, Texas (USA), a city located on the international border between the United States and Mexico. Integrated measurements of NO(2) were collected over 7 days at 20 elementary schools and 4 air quality monitoring stations located throughout the city during typical winter atmospheric conditions. Replicate passive monitors were co-located with chemiluminescence analyzers at the monitoring stations for two consecutive 7-day periods. The passive measurements correlated with the analyzer measurements (R(2)=0.74) with precision of 2.5+/-2.2 ppb. Nitrogen dioxide concentrations ranged from 11.0 to 37.5 ppb (mean 20.6+/-7.1 ppb). In a multivariate regression model, the site elevation and distances to a main highway and to an international port of entry from Mexico explained 81% of the variance in the passive measurements. The results of this pilot study indicate that proximity to vehicle-related sources of NO(2) and site elevation are key predictors for future, more detailed assessments of vehicle-related air pollution exposure in the El Paso region.

Air Pollutants↗

PubMed2005

Randomized, placebo-controlled trial of albuterol and epinephrine at equipotent beta-2 agonist doses in acute bronchiolitis.

Our objective was to determine if nebulized racemic epinephrine is more efficacious than nebulized albuterol or saline placebo in the treatment of bronchiolitis in the outpatient setting when dosing is equivalent in terms of beta-2 agonist potency. Sixty-five patients between ages 6 weeks and 24 months with a diagnosis of bronchiolitis, defined as first-time wheezing, upper respiratory symptoms and/or fever, and a Respiratory Distress Assessment Instrument score of at least 4, were randomized to receive 5 mg nebulized albuterol, 5 mg nebulized racemic epinephrine, or an equivalent volume of placebo at 0, 30, and 60 min. The primary outcome measure was need for hospital admission or home oxygen. Secondary outcome measures were changes in clinical scores and oxygen saturations. There were no significant statistical differences between groups in terms of need for hospital admission or outpatient management with home oxygen therapy. There were no differences between groups in terms of changes in clinical scores or oxygen saturations. Racemic epinephrine and albuterol at equivalent doses had no effect on the need for hospitalization or supplemental oxygen in bronchiolitis in the outpatient setting compared to nebulized saline placebo, though this study may have missed less dramatic clinical effects due to small sample size.

Acute Disease↗

PubMed2005

Emotional responses to APO E genotype disclosure for Alzheimer disease.

The purpose of our study is to assess the emotional responses to disclosing APO E genotype to asymptomatic older adults at increased risk for Alzheimer disease (AD). This is a longitudinal cohort study of volunteer subjects who were aged 50 years or over, asymptomatic for (AD), had a family history of AD, passed a psychological assessment, and participated in pre- and post-test genetic counseling and three follow-up visits over 10 months. We analyzed responses by three emotional constructs: depressed, worried, and relieved. Three hundred and twenty-eight subjects were screened, 76 received their APO E genotype. When emotional responses occurred it was immediate, between baseline and the 1 month follow-up. Emotional reactions did not change significantly past 1 month. Our results suggest that for emotionally stable persons, disclosing results of their APO E genotype, high risk subjects did not report more depression or worry and low risk subjects felt relieved by knowing the results. Future studies should evaluate the risks of disclosure to family members involved in the diagnostic work-up of a relative and include subjects from a broader range of emotional stability and socioeconomic background.

Affect↗