Biomedical subjects

C Miller

Publications and source records attributed to C Miller.

At least 91 records · Page 5Linked to original sources

PubMed2000

Tethered blockers as molecular 'tape measures' for a voltage-gated K+ channel.

The propagation of electrical signals in excitable cells is orchestrated by a molecular family of voltage-dependent ion channel proteins. These K+, Na+, and Ca++ channels are all composed of four identical or similar units, each containing six transmembrane segments (S1-S6) in a roughly four-fold symmetric structure. The S5-S6 sequences fold into a central pore unit, which is surrounded by a voltage-gating module composed of S1-S4. The recent structure of KcsA, a two-transmembrane bacterial K+ channel, illuminates the physical character of the pore unit, but little is known about the arrangement of the surrounding S1-S4 sequences. To locate regions of this gating module in space, we synthesized a series of compounds of varying length that function as molecular 'tape measures': quaternary ammonium (QA) pore blockers that can be tethered to specific test residues. We show that in a Shaker K+ channel, the extracellular ends of S1 and S3 are approximately 30 ¿ from the tetraethylammonium (TEA) blocking site at the external opening of the pore. A portion of the S3-S4 loop is, at 17-18 ¿, considerably closer.

Amino Acid Substitution↗

PubMed2000

The lipid-protein interface of a Shaker K(+) channel.

Tryptophan-substitution mutagenesis was applied to the first and third transmembrane segments (S1 and S3) of a Shaker-type K(+) channel for the purpose of ascertaining whether these sequences are alpha-helical. Point mutants were examined for significant functional changes, indicated by the voltage-activation curves and gating kinetics. Helical periodicity of functional alteration was observed throughout the entire S1 segment. A similar result was obtained with the first 14 residues of S3, but this periodicity disappeared towards the extracellular side of this transmembrane sequence. In both helical stretches, tryptophan-tolerant positions are clustered on approximately half the alpha-helix surface, as if the sidechains are exposed to the hydrocarbon region of the lipid bilayer. These results, combined with an analogous study of S2 (Monks, S., D.J. Needleman, and C. Miller. 1999. J. Gen. Physiol. 113:415-423), locate S1, S2, and S3 on the lipid-facing periphery of K(v) channels.

Animals↗

PubMed2000

Consequences of reducing nonresponse in a national telephone survey.

Critics of public opinion polls often claim that methodological shortcuts taken to collect timely data produce biased results. This study compares two random digit dial national telephone surveys that used identical questionnaires but very different levels of effort: a "Standard" survey conducted over a 5-day period that used a sample of adults who were home when the interviewer called, and a "Rigorous" survey conducted over an 8-week period that used random selection from among all adult household members. Response rates, computed according to AAPOR guidelines, were 60.6 percent for the Rigorous and 36.0 percent for the Standard study. Nonetheless, the two surveys produced similar results. Across 91 comparisons, no difference exceeded 9 percentage points, and the average difference was about 2 percentage points. Most of the statistically significant differences were among demographic items. Very few significant differences were found on attention to media and engagement in politics, social trust and connectedness, and most social and political attitudes, including even those toward surveys.

Journal Article↗

PubMed2000

Wrapping and interoperating bioinformatics resources using CORBA.

Bioinformaticians seeking to provide services to working biologists are faced with the twin problems of distribution and diversity of resources. Bioinformatics databases are distributed around the world and exist in many kinds of storage forms, platforms and access paradigms. To provide adequate services to biologists, these distributed and diverse resources have to interoperate seamlessly within single applications. The Common Object Request Broker Architecture (CORBA) offers one technical solution to these problems. The key component of CORBA is its use of object orientation as an intermediate form to translate between different representations. This paper concentrates on an explanation of object orientation and how it can be used to overcome the problems of distribution and diversity by describing the interfaces between objects.

Amino Acid Sequence↗

PubMed2000

Inhibition of neutrophil apoptosis after severe trauma is NFkappabeta dependent.

BACKGROUND: Systemic inflammation may inhibit neutrophil (PMN) apoptosis and promote multiple organ dysfunction syndrome. We hypothesize that severe trauma causes dysregulation of PMN apoptosis. METHODS: Neutrophils were isolated from trauma patients (24-72 hours after injury; n = 16) and controls (healthy volunteers) and incubated for 18 hours. In separate experiments, control cells were treated +/- the nuclear factor kappa beta (NFkappabeta) inhibitor pyrrolidinithiocarbamate then incubated with 25% patient or control plasma. Apoptosis was quantified by enzyme-linked immunosorbent assay for histone-associated DNA and annexin V fluorescence-activated cell sorter. NFkappabeta activation was determined by Western blot for phosphorylated I kappabeta. RESULTS: Apoptosis was inhibited in trauma patient PMN. Neutrophil apoptosis correlated with multiple organ dysfunction syndrome score, Acute Physiology and Chronic Health Evaluation II, and platelet count. Patient plasma inhibited apoptosis and induced phosphorylation of I kappabeta in control cells. Inhibition of PMN apoptosis by patient plasma was blocked by pretreatment with pyrrolidinithiocarbamate. CONCLUSION: NFkappabeta-dependent inhibition of neutrophil apoptosis occurs after trauma. Early inhibition of PMN apoptosis is dependent on the magnitude of injury.

Apoptosis↗

PubMed2000

Inhibited neutrophil apoptosis: proteasome dependent NF-kappaB translocation is required for TRAF-1 synthesis.

Neutrophil (PMN) apoptosis regulates local and systemic inflammation during sepsis. Tumor necrosis factor receptor-associated factors (TRAFs) have been implicated as mediators of apoptosis; however, the signaling pathways for their production in stimulated PMN are unclear. We hypothesize that NF-kappaB translocation is necessary for the induction of TRAF-1 in PMNs with prolonged survival. Neutrophils were isolated from the blood of healthy volunteers by Ficoll gradient centrifugation and red blood cell sedimentation. Neutrophil NF-kappaB was inhibited with a proteasome inhibitor, PSI-I. Cells were treated with PSI-I (30 microM) or vehicle (DMSO 0.2%) for 50 min then incubated over an 18-h time course with LPS (10 to 1000 ng/mL), tumor necrosis factor alpha (TNFalpha) (2 to 20 ng/mL) or control media. In vitro apoptosis was quantified by propidium iodide FACS analysis. Total cellular TRAF-1 was detected by Western blot analysis of cell lysates. Steady state TRAF-1 mRNA was detected by RPA. NF-kappaB activity was determined by Western blot analysis for nuclear p65. Means and standard errors were calculated; data were analyzed by ANOVA. Lipopolysaccharide (LPS) and TNFalpha increased PMN nuclear p65 and steady state TRAF-1 mRNA. Apoptosis was inhibited by TNFalpha and LPS at 12 and 18 h (P < 0.01). Incubation of cells in the NF-kappaB inhibitor PSI-I blocked LPS and TNFalpha-induced inhibition of apoptosis (P < 0.05) and the induction of both nuclear p65 and TRAF-1 mRNA. These data demonstrate that inhibition of PMN apoptosis and TRAF-1 induction by LPS and TNFalpha is NF-kappaB dependent.

Apoptosis↗

PubMed2000

Effect of a cellulose acetate phthalate topical cream on vaginal transmission of simian immunodeficiency virus in rhesus monkeys.

Human immunodeficiency virus type 1 (HIV-1) infection continues to spread in developing countries, mostly through heterosexual transmission. The development of a safe and cost-effective topical microbicide, effective against a range of STDs including HIV-1, would greatly impact the ongoing epidemic. When formulated in a vehicle, a micronized form of cellulose acetate phthalate (CAP), which is an inactive pharmaceutical excipient, has been shown to inactivate HIV-1, herpes simplex virus types 1 and 2, cytomegalovirus, Neisseria gonorrhoeae, Trichomonas vaginalis, Haemophilus ducreyi, and Chlamydia trachomatis in vitro. Formulated CAP was also shown to be effective against herpes simplex virus type 2 in vivo. Here we show that a formulation of CAP protected four of six rhesus monkeys from vaginal infection with simian immunodeficiency virus. Thus, CAP may be a candidate for use as a topical microbicide for preventing HIV-1 infection in humans.

Administration, Topical↗

PubMed2000

Host resistance and immune deviation in pigeon cytochrome c T-cell receptor transgenic mice infected with Toxoplasma gondii.

Resistance to Toxoplasma gondii has been shown to be mediated by gamma interferon (IFN-gamma) produced by NK, CD4(+), and CD8(+) T cells. While studies of SCID mice have implicated NK cells as the source of the cytokine in acute infection, several lines of evidence suggest that IFN-gamma production by CD4(+) T lymphocytes also plays an important role in controlling early parasite growth. To evaluate whether this function is due to nonspecific as opposed to T-cell receptor (TCR)-dependent stimulation by the parasite, we have examined the resistance to T. gondii infection of pigeon cytochrome c transgenic (PCC-Tg) Rag-2(-/-) mice in which all CD4(+) T lymphocytes are unreactive with the protozoan. When inoculated with the ME49 strain, PCC-Tg animals exhibited only temporary control of acute infection and succumbed by day 17. Intracellular cytokine staining by flow cytometry revealed that, in contrast to infected nontransgenic controls, infected PCC-Tg animals failed to develop IFN-gamma-producing CD4(+) T cells. Moreover, the CD4(+) lymphocytes from these mice showed no evidence of activation as judged by lack of upregulated expression of CD44 or CD69. Nevertheless, when acutely infected transgenic mice were primed by PCC injection, the lymphokine responses measured after in vitro antigen restimulation displayed a strong Th1 bias which was shown to be dependent on endogenous interleukin 12 (IL-12). The above findings argue that, while T. gondii-induced IL-12 cannot trigger IFN-gamma production by CD4(+) T cells in the absence of TCR ligation, the pathogen is able to nonspecifically promote Th1 responses against nonparasite antigens, an effect that may explain the immunostimulatory properties of T. gondii infection.

Acute Disease↗

PubMed2000

A decade of CLC chloride channels: structure, mechanism, and many unsettled questions.

ClC-type chloride channels are ubiquitous throughout the biological world. Expressed in nearly every cell type, these proteins have a host of biological functions. With nine distinct homologues known in eukaryotes, the ClCs represent the only molecularly defined family of chloride channels. ClC channels exhibit features of molecular architecture and gating mechanisms unprecedented in other types of ion channels. They form two-pore homodimers, and their voltage-dependence arises not from charged residues in the protein, but rather via coupling of gating to the movement of chloride ions within the pore. Because the functional characteristics of only a few ClC channels have been studied in detail, we are still learning which properties are general to the whole family. New approaches, including structural analyses, will be crucial to an understanding of ClC architecture and function.

Animals↗

PubMed2000

Thoracoabdominal asynchrony failed to grade airway obstructions in foals.

Respiratory inductive plethysmography (RIP) can be used to obtain a valid measure of tidal volume in humans. This device also compares the contributions to ventilation of the thorax and abdomen. Although thoracoabdominal asynchrony is a prominent clinical feature for patients with airway obstruction, the accuracy of the RIP device to assess the severity of obstruction is unclear. This study analyzes how well RIP variables reflect the degree of a fixed external inspiratory plus expiratory resistive load in foals. Foals were employed because the species and age group are commonly afflicted with respiratory disease. Eight conscious, sedated (xylazine 1.25 mg/kg body wt) foals were subjected to randomly ordered resistive loads at the airway opening and, on a separate day, to histamine aerosol challenge. During resistive loading, phase angle changed significantly, as did phase relation (P < or = 0.05). However, no significant correlation was found between the degree of change in resistive load and the degree to which phase angle or relation was altered (r(s) = 0.41 and 0.25, respectively). In addition, neither phase angle nor relation changed significantly with histamine challenge. We conclude that, although RIP variables changed markedly with fixed upper airway resistive loading, the degree to which they changed was erratic and therefore not useful for grading these obstructions. Furthermore, RIP variables were insensitive measures of histamine-induced bronchoconstriction.

Abdomen↗

PubMed2000

A comparison of patterns of tranquiliser intake, anxiety and health locus of control between short- and long-term benzodiazepine users.

This study investigates the impact of physical illness, health locus of control and anxiety level on long- and short-term benzodiazepine (BZD) use in patients of an internal medicine department. There was no significant difference observed between the continuing and discontinuing group after hospital admission in terms of average daily dose of BZD. However, the continuing patients rated the condition of their somatic illness significantly higher than the discontinuing group, although this difference was not confirmed by the objective assessment of the treating physician. The non-continuing group displayed significantly higher control over health- and sickness-related events. The somatic and physical anxiety factor was significantly higher in the continuing group at initial investigation as well as at follow-up. On the basis of these results, we conclude that an increased focus on the psychosomatic element might reduce the risk of long-term tranquiliser use in patients with physical illness.

Anti-Anxiety Agents↗

PubMed2000

Pediatric fiberoptic endoscopic evaluation of swallowing.

Pediatric dysphagia is the presenting feature of many underlying diagnoses. Between July 1993 and July 1999, 643 fiberoptic endoscopic evaluations of swallowing (FEES) were performed on 568 patients. The median age of the population was 2.5 years (range, 3 days to 21 years). The principal medical and surgical diagnoses of the patients at the time of presentation to the FEES clinic were prospectively recorded: 36% of the patients presented with a diagnosis of structural abnormalities of the upper aerodigestive tract or airway; 26% with neurologic diagnoses; 12% with gastroenterological disorders; 8% with genetic syndromes; 7% with pulmonary dysfunction; 5% with prematurity; 3% with cardiovascular anomalies; and 2% with metabolic problems. The patients were classified according to the following feeding regimens: 9% normally fed; 38% orally fed with limitations; 13% orally fed, but with required supplemental tube feedings; and 40% prohibited from taking nutrition orally. The FEES enabled the following classification of feeding abnormalities: 15% had normal feeding; 56% exhibited behavioral abnormalities, including sensory-based feeding disorders; 15% exhibited structural abnormalities; 16% exhibited neurologic abnormalities; 1.5% exhibited metabolic abnormalities; and 0.5% exhibited cardiorespiratory abnormalities. The unique aspects of pediatric dysphagia are highlighted, and the role of FEES in the workup of this challenging aspect of pediatric otolaryngology is discussed.

Abnormalities, Multiple↗

PubMed2000

Neuropsychological counseling improves social behavior in cognitively-impaired multiple sclerosis patients.

We studied the effectiveness of a newly-developed cognitive-behavioral intervention in 15 patients with marked cognitive impairment and behavior disorder. The design was a single-blind test of a neuropsychological intervention, with pre- and post-treatment assessments of personality and social behavior. MS patients underwent neurological examination and neuropsychological testing at baseline. The patients were then randomly assigned to neuropsychological counseling or standard, non-specific supportive psychotherapy. The active 12-week treatment emphasized enhancement of insight through education, social skills training, and behavior modification. All patients were re-examined within 2 weeks of the termination of treatment. Neuropsychological technicians were blind to treatment condition. Both groups showed evidence of cognitive impairment and personality/behavior disorder prior to treatment and were well matched on demographic, disability, and cognitive measures. Patients who underwent neuropsychological counseling showed significant positive response on measures of social behavior (e.g. excessive ego-centric speech) compared to those who underwent standard counseling. We conclude that these data support the use of non-pharmacological, neuropsychological counseling in patients with acquired, MS-associated behavior disorder.

Adult↗

PubMed2000

Image restoration with the Viterbi algorithm.

The Viterbi algorithm (VA) is known to given an optimal solution to the problem of estimating one-dimensional sequences of discrete-valued pixels corrupted by finite-support blur and memoryless noise. A row-by-row estimation along with decision feedback and vector quantization is used to reduce the computational complexity of the VA and allow the estimation of two-dimensional images. This reduced-complexity VA (RCVA) is shown to produce near-optimal estimation of random binary images. In addition, simulated restorations of gray-scale images show the RCVA estimates to be an improvement over the estimates obtained by the conventional Wiener filter (WF). Unlike the WF, the RCVA is capable of superresolution and is adaptable for use in restoring data from signal-dependent Poisson noise corruption. Experimental restorations of random binary data gathered from an optical imaging system support the simulations and show that the RCVA estimate has fewer than one third of the errors of the WF estimate.

Algorithms↗

PubMed2000

Decreased natural killer cell responses and altered interleukin-6 and interleukin-10 production in alcoholism: an interaction between alcohol dependence and African-American ethnicity.

BACKGROUND: Epidemiological data indicate that among alcoholics African-American men have higher rates of infections compared with white alcoholics. Alcohol is thought to reduce natural killer (NK) cell responses and to alter cellular immunity by changing the relative balance of Th1 versus Th2 cytokine response profiles. However, translation of these basic immunological observations into the clinical setting is limited, and what clinical data are available are contradictory, in part, because of heterogeneity within the alcoholic patient population. Whether ethnic characteristics contribute to variation in the immunological effects of alcohol is not known. METHODS: This study compared NK activity, interleukin (IL)-2-stimulated NK activity, and concanavalin A-stimulated peripheral blood mononuclear cell production of Th1 (IL-12 and IL-2), Th2 (IL-10), and proinflammatory (IL-6) cytokines in 31 hospitalized chronic alcoholic patients and 31 age-matched controls who were stratified on the basis of ethnicity. RESULTS: NK-cell responses were significantly different across the four groups, and African-American alcoholics showed the lowest levels of NK activity (F = 9.5;p < 0.001) and IL-2-stimulated NK activity (F = 2.9; p < 0.05). Compared with the other three groups, African-American alcoholics also showed lower levels of IL-6 (F = 7.2;p < 0.01) and higher levels of IL-10 (F = 4.9;p < 0.05). Stimulated production of IL-2 and IL-12 were similar in the four groups. Regression analyses showed that alcohol dependence and ethnicity predicted NK activity, whereas the interaction between alcohol dependence and ethnicity predicted levels of IL-6 and IL-10. CONCLUSIONS: In summary, the immunological effects of alcohol dependence are modified by ethnicity status, consistent with the increased health risks found in African-American alcoholics.

Adult↗

PubMed2000

Sleep and mood during a winter in Antarctica.

Seasonal variations in sleep characteristics and their association with changes in mood were examined in 91 American men and women who spent the 1991 austral winter at three different research stations in Antarctica. Measures of total hours of sleep over a 24-hr period, duration of longest (i.e., "nighttime") sleep event, number of sleep events, time of sleep onset, and quality of sleep remained unchanged over the course of the austral winter (March through October). However, exposure to total darkness based on station latitude was significantly associated with total hours of sleep, duration of longest sleep event, time of sleep onset, and quality of sleep. Reported vigor the previous month was a significant independent predictor of changes in all five sleep measures; previous month's measures of all six POMS subscales were significant independent predictors of sleep quality. Sleep characteristics were significant independent predictors of vigor and confusion the following month; total sleep, longest sleep event, sleep onset and sleep quality were significant independent predictors of tension-anxiety and depression. Changes in mood during the austral winter are preceded by changes in sleep characteristics, but prolonged exposure to the photo-periodicity characteristic of the high latitudes appears to be associated with improved sleep. In turn, mood changes appear to affect certain sleep characteristics, especially sleep quality.

Adult↗

PubMed2000

Predictors of behavior and performance in extreme environments: the Antarctic space analogue program.

BACKGROUND: To determine which, if any, characteristics should be incorporated into a select-in approach to screening personnel for long-duration spaceflight, we examined the influence of crewmember social/ demographic characteristics, personality traits, interpersonal needs, and characteristics of station physical environments on performance measures in 657 American men who spent an austral winter in Antarctica between 1963 and 1974. METHODS: During screening, subjects completed a Personal History Questionnaire which obtained information on social and demographic characteristics, the Deep Freeze Opinion Survey which assessed 5 different personality traits, and the Fundamental Interpersonal Relations Orientation-Behavior (FIRO-B) Scale which measured 6 dimensions of interpersonal needs. Station environment included measures of crew size and severity of physical environment. Performance was assessed on the basis of combined peer-supervisor evaluations of overall performance, peer nominations of fellow crew-members who made ideal winter-over candidates, and self-reported depressive symptoms. RESULTS: Social/demographic characteristics, personality traits, interpersonal needs, and characteristics of station environments collectively accounted for 9-17% of the variance in performance measures. The following characteristics were significant independent predictors of more than one performance measure: military service, low levels of neuroticism, extraversion and conscientiousness, and a low desire for affection from others. CONCLUSIONS: These results represent an important first step in the development of select-in criteria for personnel on long-duration missions in space and other extreme environments. These criteria must take into consideration the characteristics of the environment and the limitations they place on meeting needs for interpersonal relations and task performance, as well as the characteristics of the individuals and groups who live and work in these environments.

Adult↗

PubMed2000

Detection of cytochrome P450 and other drug-metabolizing enzyme mRNAs in peripheral blood mononuclear cells using DNA arrays.

The purpose of this study was to determine whether the expression of cytochrome P450 (CYP) enzyme mRNAs, other drug-metabolizing enzyme mRNAs, and transporter mRNAs can be detected using DNA arrays. Total RNA was isolated from peripheral blood mononuclear cells of 10 multiple sclerosis patients and 10 age- and sex-matched controls. The mRNA was reverse transcribed to radiolabeled cDNA, and the resultant cDNA was used to probe a DNA array containing several thousand known human genes. The signals corresponding to several CYPs, drug-metabolizing, and transporter mRNAs was substantially above background. The results demonstrate that the DNA array technique has the sensitivity and the selectivity for applications in the pharmaceutical sciences. The mean values for mRNAs of specific CYPs and drug-metabolizing enzymes in peripheral blood cells were compared with reported values for liver. The capabilities of DNA arrays may prove useful for characterizing CYP expression in a variety of clinical samples.

ATP Binding Cassette Transporter, Subfamily B, Mem↗