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At least 811 records · Page 45Linked to original sources
PubMed2006

Housing instability and food insecurity as barriers to health care among low-income Americans.

BACKGROUND: Homelessness and hunger are associated with poor health outcomes. Housing instability and food insecurity describe less severe problems securing housing and food. OBJECTIVE: To determine the association between housing instability and food insecurity and access to ambulatory health care and rates of acute health care utilization. DESIGN: Secondary data analysis of the National Survey of American Families. PARTICIPANTS: 16,651 low-income adults. MEASUREMENT: Self-reported measures of past-year access: (1) not having a usual source of care, (2) postponing needed medical care, or (3) postponing medication; and past-year utilization: (1) not having an ambulatory care visit, (2) having emergency department (ED) visits, or (3) inpatient hospitalization. RESULTS: 23.6% of subjects had housing instability and 42.7% had food insecurity. In multivariate logistic regression models, housing instability was independently associated with not having a usual source of care (adjusted odds ratio [AOR] 1.31, 95% confidence interval [CI] 1.08 to 1.59), postponing needed medical care (AOR 1.84, 95% CI 1.46 to 2.31) and postponing medications (AOR 2.16, 95% CI 1.70 to 2.74), increased ED use (AOR: 1.43, 95% CI 1.20 to 1.70), and hospitalizations (AOR 1.30, 95% CI 1.01 to 1.67). Food insecurity was independently associated with postponing needed medical care (AOR 1.74, 95% CI 1.38 to 2.21) and postponing medications (AOR 2.15, 95% CI 1.62 to 2.85), increased ED use (AOR 1.39, 95% CI 1.17 to 1.66), and hospitalizations (AOR 1.42, 95% CI 1.09 to 1.85). CONCLUSIONS: Housing instability and food insecurity are associated with poor access to ambulatory care and high rates of acute care. These competing life demands may lead to delays in seeking care and predispose to acute care.

Adult↗
PubMed2004

Dynamic instability in a DNA-segregating prokaryotic actin homolog.

Dynamic instability-the switching of a two-state polymer between phases of steady elongation and rapid shortening-is essential to the cellular function of eukaryotic microtubules, especially during chromosome segregation. Since the discovery of dynamic instability 20 years ago, no other biological polymer has been found to exhibit this behavior. Using total internal reflection fluorescence microscopy and fluorescence resonance energy transfer, we observe that the prokaryotic actin homolog ParM, whose assembly is required for the segregation of large, low-copy number plasmids, displays both dynamic instability and symmetrical, bidirectional polymerization. The dynamic instability of ParM is regulated by adenosine triphosphate (ATP) hydrolysis, and filaments are stabilized by a cap of ATP-bound monomers. ParM is not related to tubulin, so its dynamic instability must have arisen by convergent evolution driven by a set of common constraints on polymer-based segregation of DNA.

Actins↗
PubMed2006

Correlation of functional instability and community dynamics in denitrifying dispersed-growth reactors.

Understanding the relationship between microbial community dynamics and functional instability is an important step towards designing reliable biological water treatment systems. In this study, the community dynamics of two dispersed-growth denitrifying reactors were examined during periods of functional stability and instability. In both reactors during the period of functional instability, the effluent chemistry changed over time, with periods of high nitrate concentrations followed by periods of fluctuating nitrite concentrations. Community structure was examined by clone library analysis of the 16S rRNA gene. Community dynamics were investigated with terminal restriction fragment (T-RF) length polymorphism, and the functional diversity represented by T-RFs was assessed through nitrate reduction assays of representative isolates. During the period of functional instability, the community structure changed considerably, and the dynamics correlated significantly with effluent chemistry. The nitrite concentration was significantly correlated with the relative abundances of the nitrate-reducing Delftia- and Achromobacter-like T-RFs. The isolate representing the Acidovorax-like T-RF reduced nitrate directly to nitrogen in batch assays without the accumulation of any intermediates. The Acidovorax-like T-RF relative abundance was significantly negatively correlated with nitrite concentration, indicating that it was associated with good functional performance. The results of this study reveal a clear relationship between community dynamics and functional instability and the importance of diversity among nitrate-reducing populations within a denitrifying community.

Bacteria↗
PubMed1980

Structural instability of IncP-1 plasmids in Pseudomonas aeruginosa PAT involves interaction with plasmid pVS1.

The structural instability exhibited by IncP-1 plasmids in Pseudomonas aeruginosa strain PAT was shown to be Rec+ dependent and involved interaction with the resident plasmid pVS1. Structural instability resulted from deletion of plasmid deoxyribonucleic acid at a frequency of ca. 10(-2)/cell per generation. Deletants could be stabilized by transduction into P. aeruginosa strain PAO, but in strain PAT deletants had only a transient existence, as continued deletion led eventually to the loss of the entire plasmid. The patterns of markers lost in PAT were used to demonstrate a marker order for R68 similar to that published elsewhere for RP4 (Barth and Grinter, J. Mol. Biol. 113:455-474, 1977), except that only one Tra region was found. R68 also exhibited Rec+-dependent structural instability in PAO(pVS1) derivatives but, unlike the case in PAT, instability was not accompanied by chromosome mobilization. We isolated deletants of pVS1 which were unable to promote structural instability.

Genetic Markers↗
PubMed1996

Clonal analysis of delayed karyotypic abnormalities and gene mutations in radiation-induced genetic instability.

Many tumors exhibit extensive chromosomal instability, but karyotypic alterations will be significant in carcinogenesis only by influencing specific oncogenes or tumor suppressor loci within the affected chromosomal segments. In this investigation, the specificity of chromosomal rearrangements attributable to radiation-induced genomic instability is detailed, and a qualitative and quantitative correspondence with mutagenesis is demonstrated. Chromosomal abnormalities preferentially occurred near the site of prior rearrangements, resulting in complex abnormalities, or near the centromere, resulting in deletion or translocation of the entire chromosome arm, but no case of an interstitial chromosomal deletion was observed. Evidence for chromosomal instability in the progeny of irradiated cells also included clonal karyotypic heterogeneity. The persistence of instability was demonstrated for at least 80 generations by elevated mutation rates at the heterozygous, autosomal marker locus tk. Among those TK- mutants that showed a loss of heterozygosity, a statistically significant increase in mutation rate was observed only for those in which the loss of heterozygosity encompasses the telomeric region. This mutational specificity corresponds with the prevalence of terminal deletions, additions, and translocations, and the absence of interstitial deletions, in karyotypic analysis. Surprisingly, the elevated rate of TK- mutations is also partially attributable to intragenic base substitutions and small deletions, and DNA sequence analysis of some of these mutations is presented. Complex chromosomal abnormalities appear to be the most significant indicators of a high rate of persistent genetic instability which correlates with increased rates of both intragenic and chromosomal-scale mutations at tk.

B-Lymphocytes↗
PubMed2003

Energy cost of walking and gait instability in healthy 65- and 80-yr-olds.

This study tested whether the lower economy of walking in healthy elderly subjects is due to greater gait instability. We compared the energy cost of walking and gait instability (assessed by stride to stride changes in the stride time) in octogenarians (G80, n = 10), 65-yr-olds (G65, n = 10), and young controls (G25, n = 10) walking on a treadmill at six different speeds. The energy cost of walking was higher for G80 than for G25 across the different walking speeds (P < 0.05). Stride time variability at preferred walking speed was significantly greater in G80 (2.31 +/- 0.68%) and G65 (1.93 +/- 0.39%) compared with G25 (1.40 +/- 0.30%; P < 0.05). There was no significant correlation between gait instability and energy cost of walking at preferred walking speed. These findings demonstrated greater energy expenditure in healthy elderly subjects while walking and increased gait instability. However, no relationship was noted between these two variables. The increase in energy cost is probably multifactorial, and our results suggest that gait instability is probably not the main contributing factor in this population. We thus concluded that other mechanisms, such as the energy expenditure associated with walking movements and related to mechanical work, or neuromuscular factors, are more likely involved in the higher cost of walking in elderly people.

Adult↗
PubMed1998

Clinical aspects of detrusor instability and the value of urodynamics: a review of the evidence.

The term unstable bladder was introduced as a description of an observation not implying pathology. In some patients, special provocative maneuvers may be needed to demonstrate it. It is variable from one test to another. It is observed in some healthy volunteers. Therefore, detrusor instability observed during urodynamic testing is not a medical condition and may not necessarily be clinically relevant. In an individual patient the clinical relevance of the observation must be judged in relation to symptoms and signs of bladder dysfunction. In the field of female incontinence there is general agreement that, statistically, the pre-operative observation of detrusor instability implies poorer results of anti-incontinence surgery. However, some incontinent patients with detrusor instability are improved by surgery. Consequently, different authors draw different conclusions about the clinical relevance of detrusor instability, but no author considers that detrusor instability is an absolute contraindication to surgery for stress incontinence.

Female↗
PubMed1988

Combined detrusor instability and stress urinary incontinence: where is the primary pathology?

Thirty-nine patients (from a total of 307 women) with clinical and urodynamic diagnosis of stress urinary incontinence had cystometric findings consistent with detrusor instability. Detailed multichannel urethrocystometry of these 39 patients revealed that urethral relaxation preceded the bladder contraction by 2-5 s. These patients were randomly allocated to either medical treatment (n = 21) by Ditropan 5 mg t.i.d. for 6 weeks prior to the surgical procedure, or to surgical treatment (n = 18) with no attempt to treat the bladder instability prior to surgery. All patients had repeat clinical and urodynamic evaluation at 3-12 months postoperatively. Six of the 39 patients (15%) still had urethral relaxation and bladder contractions on postoperative urethrocystometry. Four of these 6 patients still had stress urinary incontinence and urethral funneling. These 4 were considered surgical failures. Two of the 39 (5%) had postoperative detrusor instability in spite of good surgical results. This series suggests that in women with combined stress urinary incontinence and bladder instability, where bladder contraction is preceded by urethral relaxation, there is a more than 90% chance that bladder instability will disappear after successful operation for stress urinary incontinence.

Adult↗
PubMed1988

Colposuspension in patients with combined stress incontinence and detrusor instability.

Thirty women with combined urinary stress incontinence and detrusor instability were treated by a colposuspension operation for urinary incontinence. Following surgery we found a significant reduction of symptoms regarding detrusor instability, from 22/30 patients preoperatively (73.3%) to 10/30 patients (33.3%). Urodynamically, 40% of the patients had detrusor instability following surgery. Only one surgical failure was encountered (3.3%). It is suggested that patients with combined detrusor instability and stress incontinence should be operated on. This group of patients was cured as far as stress incontinence is considered, and 60% of the patients presented normal cystometric findings and more than 50% of the patients (12/22) greatly improved clinically, regarding symptoms of detrusor instability, following surgery.

Adult↗
PubMed1996

Relationship of genetic instability with immunoreactivities for p53 protein and proliferating cell nuclear antigen in transitional cell carcinoma of the bladder.

OBJECTIVE: To elucidate the relationship between genetic instability and tumor development in transitional cell carcinoma (TCC) of the bladder. METHODS: The genetic instability as assessed by 2c deviation index (2cDI) and 5c exceeding rate (5cER) was compared with immunoreactivities for p53 protein and proliferating cell nuclear antigen (PCNA) in specimens obtained from 65 patients with primary untreated TCCs. RESULTS: Both p53 and PCNA immunoreactivities significantly correlated with histological grade as well as stage. The immunoreactivity of p53 significantly correlated with that of PCNA, while a dissociation of the positive correlation between p53 immunoreactivity and PCNA expression was noted in the TCCs with high 2cDI value (> or = 2.0) and/or high 5cER (> or = 10%). In addition, PCNA expression became higher as the genetic instability increased, however, the p53 immunoreactivity was not parallel with the change of genetic instability. Moreover, some TCCs with high genetic instability (2cDI > or = 2.0 and 5cER > or = 10%) showed concomitant expression of high PCNA and low p53 protein, whose clinical outcome was poor in general. CONCLUSIONS: The inactivation of p53 may represent a rather early event in the development of TCC of the bladder. However, the proliferative activity in itself rather than the effect due to a specific alteration in p53 plays an important role in the development and progression in TCC of the bladder.

Carcinoma, Transitional Cell↗
PubMed1983

The effects of reperfusion and retrograde coronary flow bleeding after coronary occlusion on induced electrical instability in the dog.

Reperfusion achieved by streptokinase infusion early after myocardial infarction (MI) is now being performed in patients, but the effect on electrical instability of increasing or decreasing perfusion in the region at risk for MI is unknown. Accordingly, 34 dogs were randomized to control (13 dogs), reperfusion (11 dogs) and retrograde bleeding (10 dogs) groups. All dogs underwent coronary artery occlusion (23 of the left anterior descending and 11 of the circumflex artery). In the control dogs, occlusion was permanent. In the reperfused dogs, the occlusion was released at 2 hours. In the retrograde bleeding dogs, retrograde flow bleeding distal to the occlusive tie was continued for 2 hours after coronary occlusion. Four days later, all dogs underwent a standard right ventricular pacing protocol. Induced arrhythmias were scored; ventricular fibrillation was assigned the highest score, followed by sustained ventricular tachycardia, nonsustained ventricular tachycardia and repetitive ventricular response. Arrhythmias provocable later in diastole were assigned higher scores than those provocable early in diastole. Infarct size was not different in the three groups (35%, 28% and 39% of the area at risk in control, reperfusion and retrograde bleeding groups, respectively). However, the electrical instability index was lower in the reperfusion group than in the other two groups (e.g., electrical instability index A at 200 beats/min: p less than 0.005 for reperfusion vs control; p less than 0.01 for reperfusion vs retrograde bleeding). Retrograde bleeding did not alter the electrical instability index from the control state. These results suggest that despite no significant reduction in infarct size, reperfusion after infarction may reduce electrical instability.

Animals↗
PubMed1999

Frequency and determinants of postprocedural hemodynamic instability after carotid angioplasty and stenting.

BACKGROUND AND PURPOSE: Hemodynamic instability can occur acutely after carotid angioplasty and stent placement (CAS). We performed this study to determine the frequency of hemodynamic instability in a series of patients who underwent CAS and to analyze factors associated with development of postprocedural hemodynamic events. METHODS: We reviewed medical records and angiograms in a series of 51 patients (mean age 68.3+/-8.9 years) who underwent CAS for symptomatic (n=29) or asymptomatic (n=22) carotid artery stenosis. Any episodes of hypotension (systolic blood pressure <90 mm Hg), hypertension (systolic blood pressure >160 mm Hg), or bradycardia (heart rate <60 bpm) that occurred in the acute postprocedural period were recorded. The effect of demographic, clinical, intraprocedural, and angiographic factors on subsequent development of hemodynamic instability was analyzed by logistic regression. RESULTS: The frequency of postprocedural hemodynamic complications in our patient series was as follows: hypotension, 22.4%; hypertension, 38.8%; and bradycardia, 27.5%. Intraprocedural hypotension (odds ratio [OR] 14.6, P=0.024) and history of myocardial infarction (OR 14.1, P=0.04) independently predicted postprocedural hypotension. Postprocedural hypertension was predicted by intraprocedural hypertension (OR 7.6, P=0.01) and previous ipsilateral carotid endarterectomy (OR 7.6, P=0.02). Postprocedural bradycardia was associated with intraprocedural hypotension (OR 74, P=0.001) and intraprocedural bradycardia (OR 12, P=0.008). All events had resolved at the conclusion of the intensive care unit monitoring period (mean 25.7 hours, range 18 to 43 hours). CONCLUSIONS: Postprocedural hemodynamic instability is frequent after CAS and supports the need for monitoring in settings suited to expeditious management of cardiovascular emergencies. Patients who have evidence of hemodynamic instability during the procedure are at highest risk.

Aged↗
PubMed2006

Neuroticism and affective instability: the same or different?

OBJECTIVE: The purpose of this study was to examine the correlates and consequences of two constructs related to affective experience: neuroticism and affective instability. METHOD: One hundred thirty-two patients were assessed at intake for axis I and II symptoms, general personality traits, and specific impairments, including impairments in interpersonal functioning. The data included responses to structured and semistructured interviews, self-reports of interpersonal problems, and reports of interpersonal problems from significant others. Clinical ratings of axis I and II symptoms and of impairment were made by using the LEAD (i.e., longitudinal, expert, all data) consensus approach. Ninety-one of the 132 patients were reassessed at 12-month follow-up. RESULTS: Neuroticism and affective instability manifested varied concurrent relations, with neuroticism being strongly related to an anxious, avoidant style and affective instability related to more externalizing personality styles. Prospectively, neuroticism predicted later symptoms, occupational impairment, and global dysfunction, whereas affective instability predicted romantic impairment. CONCLUSIONS: The findings suggest that neuroticism and affective instability--which are considered core aspects of personality pathology--are related but distinct constructs with unique correlates and different predictive abilities.

Adult↗
PubMed2002

Characterizing affective instability in borderline personality disorder.

OBJECTIVE: This study sought to understand affective instability among patients with borderline personality disorder by examining the degree of instability in six affective domains. The authors also examined the subjective intensity with which moods are experienced and the association between instability and intensity of affect. METHOD: In a group of 152 patients with personality disorders, subjective affective intensity and six dimensions of affective instability were measured. The mean scores for lability and intensity for each affective domain for patients with borderline personality disorder were compared with those of patients with other personality disorders through analyses that controlled for other axis I affective disorders, age, and sex. RESULTS: Greater lability in terms of anger and anxiety and oscillation between depression and anxiety, but not in terms of oscillation between depression and elation, was associated with borderline personality disorder. Contrary to expectation, the experience of an increase in subjective affective intensity was not more prominent in patients with borderline personality disorder than in those with other personality disorders. CONCLUSIONS: By applying a finer-grained perspective on affective instability than those of previous personality disorder studies, this study points to patterns of affective experience characteristic of patients with borderline personality disorder.

Adult↗
PubMed1977

Determination of sagittal instability of the knee joint.

For measuring sagittal instability in the knee joint a radiologic method has been developed which requires no complicated equipment, is easy to apply, and is relatively insensitive to the sources of error commonly associated with determination of sagittal instability, such as difference of flexion angle and changes in the projection. Measurements are made between reference points located in the femur and the tibia. The reproducibility of the method is high enough to make it suitable for testing instability before and after reconstructive surgery. By the use of constructed reference points sagittal instability can be distinguished from rotational instability.

Humans↗
PubMed2005

Self-gravity driven instabilities at accelerated interfaces.

Nonlinear hydrodynamic flows are ubiquitous in the interstellar medium (ISM). Such flows play an important role in shaping atomic and molecular clouds and determining the initial conditions for star formation. One mechanism by which nonlinear flows arise is the onset and growth of interfacial instabilities. Any interface of discontinuous density is subject to a host of instabilities, including Rayleigh-Taylor, Kelvin-Helmholtz, and Richtmyer-Meshkov. As part of an ongoing study of structure formation in the ISM, Hunter, Whitaker, and Lovelace discovered an additional density interface instability. This instability is driven by self-gravity and termed the self-gravity interfacial instability (SGI). The SGI causes any displacement of the interface to grow on roughly a free-fall time scale, even when the perturbation wavelength is much less than the Jeans length. Numerical simulations have confirmed the expectations of linear theory, including the near scale invariance of the growth rate. Here, we build upon previous work by considering an initial condition in which the acceleration due to self-gravity is non-zero at the interface.

Journal Article↗
PubMed2003

Family instability and young adolescent maladjustment: the mediating effects of parenting quality and adolescent appraisals of family security.

Examined relations among family instability and adolescent's psychological functioning using family models of children's emotional security in a sample of 220 young adolescents and their primary caregivers. Primary caregiver reports of family instability were associated with multiple informant measures of adolescent internalizing and externalizing symptoms. Findings from structural equation models supported the hypothesis that family instability increases adolescent risk for psychological problems by directly undermining their insecure appraisals of the family. Results also supported a pathway whereby family instability predicted parenting difficulties and parenting difficulties, in turn, indirectly predicted adolescents' internalizing and externalizing symptoms through its association with lower levels of perceived insecurity in the family. Results are discussed in relation to how they advance process-oriented conceptualizations of family instability.

Adaptation, Psychological↗
PubMed2006

Residual pump light as a probe of self-pulsing instability in an ytterbium-doped fiber laser.

Self-pulsing instability in the ytterbium-doped fiber (YDF) laser is investigated with the pump-bypassed cavity configuration. The residual pump light acts as a probe of the intracavity dynamics, and the temporal behavior of the light shows correlations with the self-mode locking instability in the original cavity and the sustained self-pulsing instability in the modified cavity of the YDF laser. The results suggest that the interactions among stimulated emission, pump absorption and/or reabsorption could account for self-pulsing instability in the YDF laser. The pump-bypassed laser cavity configuration can be used to investigate the instabilities of various kinds of fiber lasers.

Journal Article↗