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Biomedical subjects

J McGuire

Publications and source records attributed to J McGuire.

At least 19 recordsLinked to original sources
PubMed2006

Protein concentration and adsorption time effects on fibrinogen adsorption at heparinized silica interfaces.

Heparin was modified with adipic dihydrazide and covalently linked to surface-activated silica wafers. X-ray photoelectron spectroscopy was used at each stage of derivatization and showed that successful immobilization had taken place. Surfaces were imaged with atomic force microscopy to determine the uniformity of the heparin layer as well as its thickness. In situ ellipsometry was used to estimate layer thickness as well, and to study protein concentration and adsorption time effects on the adsorption and elution kinetics exhibited by human plasma fibrinogen. The adsorbed amount of fibrinogen increased with time and concentration on each type of surface. Under all experimental conditions, fibrinogen adsorbed at a lower rate and to a lower extent on heparinized as compared to unheparinized silica. In addition, buffer elution experiments showed that fibrinogen was less tightly bound to heparinized silica. In order to examine behavior relative to fibrinogen mobility at these interfaces, the sequential adsorption of fibrinogen was recorded. The difference in adsorption rates between the first and second adsorption cycles, evaluated at identical mass density, indicated that post-adsorptive molecular rearrangements had taken place. In general, higher solution concentration and longer adsorption time in the first adsorption step led to more rearrangement, and these history dependent effects were more pronounced on the heparinized silica. These rearrangements are suggested to involve clustering of adsorbed fibrinogen, in this way increasing the amount of unoccupied area at the interface. These rearrangements were presumably facilitated on the heparinized silica by enhanced lateral mobility of fibrinogen at this negatively charged, highly hydrophilic interface.

Adipates↗
PubMed2005

An algorithm for locating the center of the ankle joint in knee navigation surgery.

The primary aim of computer-assisted knee arthroplasty is to improve the alignment of the implanted prostheses. Accurate component alignment is dependent on the establishment of accurate anatomical reference points. Current techniques for establishing the center of the ankle joint, especially in the coronal plane, rely solely on clinical judgment in relation to the position of the center of the ankle joint. The aim of this study was to determine if an algorithm could be developed, based on establishing the most prominent points on the medial and lateral malleoli on 3D CT scans, to accurately and reproducibly establish the position of the center of the ankle joint. To determine this, images of 20 ankles were obtained and axial, coronal, and sagittal 2D reconstructions were manipulated on a workstation. Two observers independently performed relevant measurements and calculations. The calculated data was found to be reproducible with a very small standard deviation in each plane. This algorithm is able to provide accurate measurements of the ankle joint in knee navigation surgery. Caution must be exercised in anatomically abnormal ankles, as the calculations of the ankle center were found to be significantly different.

Algorithms↗
PubMed2003

Effect sizes in the treatment of sexual offenders.

This article considers the benefits of sexual offender treatment in terms of the magnitude of the effect size produced by these interventions. Comparisons are made of the effect sizes with those generated by treatment of other offenders, by treatment for mental health problems, and by treatment for physical health problems. In all cases, effect sizes with sexual offenders are comparable to (and in some cases better than) effect sizes for the treatment of the other groups. As a final note, it is suggested that using a harm reduction index to estimate effect sizes for treatment with sexual offenders would produce more meaningful results.

Humans↗
PubMed2002

Comparison of acute toxicities of indolo[3,2-b]carbazole (ICZ) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in TCDD-sensitive rats.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and related halogenated aromatic hydrocarbons are environmental toxicants that act via the AH receptor (AHR). In vitro studies have demonstrated that some indole derivatives present in cruciferous vegetables also bind to the AHR. One of the highest AHR binding affinities is exhibited by indolo[3,2-b]carbazole (ICZ). Since exposure to these dietary indoles is quantitatively far larger than that to halogenated aromatic compounds, their potential toxic risks have raised concern. In the present study, we compared the effects of ICZ with those of a single dose of 20 microg/kg TCDD in the most TCDD-sensitive rat strain (Long-Evans [Turku AB]) (L-E). Whereas TCDD elicited the expected toxicity syndrome, ICZ, either as a single subcutaneous dose (63.5, 127 or 508 microg/kg) or with repeated sc dosing (508 microg/kg for 5 days) failed to reproduce any toxic impacts of TCDD. Furthermore, a simultaneous ICZ treatment (63.5 or 127 microg/kg for 10 days) did not interfere with TCDD (20 microg/kg; single exposure) action. A moderate hepatic induction of CYP1A1 could be triggered by repeated intragastric administration of ICZ (127 microg/kg for 4 days, the last treatment 2.5 h prior to termination). In control experiments in a reconstituted yeast system, ICZ potently and dose-dependently activated L-E rat AHR function demonstrating that it represents a bona fide high-affinity ligand for the rat receptor in vivo. Thus, the present study does not support the view that dietary exposure to ICZ would present a hazard of AHR-mediated adverse health effects to humans.

Animals↗
PubMed2001

Definition of a dioxin receptor mutant that is a constitutive activator of transcription: delineation of overlapping repression and ligand binding functions within the PAS domain.

The intracellular dioxin (aryl hydrocarbon) receptor is a ligand-activated transcription factor that mediates the adaptive and toxic responses to environmental pollutants such as 2,3,7,8-tetrachlorodibenzo-p-dioxin and structurally related congeners. Whereas the ligand-free receptor is characterized by its association with the molecular chaperone hsp90, exposure to ligand initiates a multistep activation process involving nuclear translocation, dissociation from the hsp90 complex, and dimerization with its partner protein Arnt. In this study, we have characterized a dioxin receptor deletion mutant lacking the minimal ligand-binding domain of the receptor. This mutant did not bind ligand and localized constitutively to the nucleus. However, this protein was functionally inert since it failed to dimerize with Arnt and to bind DNA. In contrast, a dioxin receptor deletion mutant lacking the minimal PAS B motif but maintaining the N-terminal half of the ligand-binding domain showed constitutive dimerization with Arnt, bound DNA, and activated transcription in a ligand-independent manner. Interestingly, this mutant showed a more potent functional activity than the dioxin-activated wild-type receptor in several different cell lines. In conclusion, the constitutively active dioxin receptor may provide an important mechanistic tool to investigate receptor-mediated regulatory pathways in closer detail.

Animals↗
PubMed2001

Social isolation predicts re-hospitalization in a group of older American veterans enrolled in the UPBEAT Program. Unified Psychogeriatric Biopsychosocial Evaluation and Treatment.

OBJECTIVES: Does social isolation predict re-hospitalization in a group of older men enrolled in Unified Psychogeriatric Biopsychosocial Evaluation and Treatment (UPBEAT), a mental health care-coordination project at nine Veterans Affairs Healthcare Centers nationwide? METHODS: The current study examined 123 UPBEAT patients located at West Los Angeles, whose ratings were available on the Lubben Social Network Scale (LSNS), the SF-36 scale, the Cumulative Illness Rating Scale (CIRS) and the Mental Health Index (MHI-38) Depression and Anxiety subscales. Within one year of enrollment, 55% of patients were re-hospitalized. Odds of re-hospitalization were calculated using two logistic regression models. Social isolation risk (LSNS) and demographic covariates were included. In addition, Model 1 contained depression and anxiety measures (MHI-38) and physician-rated medical burden (CIRS), while in Model 2, patient-perceived physical (PCS) and mental health (MCS) subscales from the SF-36 were included. RESULTS: The group of patients who were socially isolated or at high or moderate risk for isolation, were 4-5 times more likely to be re-hospitalized within the year, than low isolation risk patients. In both Models 1 (chi-square = 19.86; p = 0.031) and 2 (chi-square = 26.42; p = 0.002) demographic characteristics were not significant predictors of re-hospitalization, but social isolation risk was a significant predictor (Model 1: odds ratio (OR) = 5.31; 95% confidence intervals (CI) = 1.81-15.53; and Model 2: OR = 3.86; 95% CI = 1.39-10.73). In addition, MHI-Anxiety was a significant predictor (OR = 1.22; 95% CI = 1.05-1.43) in Model 1 and in Model 2, patient-perceived physical health significantly predicted re-hospitalization (OR = 0.91; 95% CI = 0.86-0.96). CONCLUSION: When controlling for other covariates, social isolation, physical health and mental health were significant risk factors for re-hospitalization. These findings underline the importance of assessing and addressing lack of social support, along with other factors, in the health care of older male veterans.

Aged↗
PubMed2001

An in vitro assessment of tissue compression damage during circular stapler approximation tests, measuring expulsion of intracellular fluid and force.

Circular staplers are among the many instruments used during minimally invasive or open surgery that should approximate soft tissue within safe compression limits. Previous in vivo suture-line blood flow measurement has suggested a safe thickness reduction limit of 25 per cent during circular stapling procedures. The present work investigates in vitro assessment of the maximum safe compression of large and small porcine intestines, measuring the required compressive force and the expelled intracellular fluid (measured as a potassium solution). A test-rig mounted on a materials testing machine allowed staplers of three sizes to compress tissue samples to thicknesses ranging from 90 to 45 per cent of original thickness. The expelled fluid was collected in 40 ml of 0.9 per cent NaCl and analysed in a flame photometer. The force measurements indicated that the small intestinal tissue samples underwent a sharp increase in stiffness over a strain range of 0.19-0.34. The large bowel tissue underwent a similar increase in stiffness over a planar compressive strain range of 0.19-0.40. The regularity of the potassium output results was limited, making it difficult to draw firm conclusions, although there was some indication that the potassium output from small intestinal tissue may change from erratic to approximately linear at a strain of approximately 0.19, while that of the large bowel tissue appeared to be approximately linear over the entire strain range tested. From the force measurements, it is concluded that strain-induced structural change may help provide a useful definition of safe tissue approximation. The possible implications for reduced dehiscence (wound disintegration) and stricture incidence in stapled anastomoses are discussed.

Animals↗
PubMed2001

Adsorption of Thermomonospora fusca E5 and Trichoderma reesei cellobiohydrolase I cellulases on synthetic surfaces.

The interfacial behavior of Thermomonosporafusca E5 and Trichoderma reesei cellobiohydrolase I (CBHI) cellulases were studied at synthetic surfaces. For this purpose, colloidal silica and polystyrene particles were used to prepare cellulase-particle suspensions that could be analyzed by solution-phase techniques. Circular dichroism spectroscopy of each cellulase, alone as well as in suspension with silica, was used to determine whether structural changes occurred on adsorption. Changes in spectra were observed for CBHI, but not for E5. Gel-permeation chromatography of the cellulase-particle suspensions showed that neither cellulase binds to silica, suggesting that changes in spectra for CBHI were a result of solution-phase phenomena. Microfiltration of cellulase-polystyrene suspensions showed that both cellulases bind to polystyrene. However, circular dichroism experiments with polysterene proved unworkable, owing to excessive light absorption by the polystyrene. Adsorption kinetics of each cellulase were recorded, in situ, at hydrophilic and silanized, hydrophobic silica surfaces using ellipsometry. Ellipsometric data recorded for each cellulase at hydrophilic silica showed insignificant adsorption. Binding did occur between each cellulase and silanized silica, most likely mediated through hydrophobic associations. Adsorption in this case was irreversible to dilution.

Actinomycetales↗
PubMed2000

Adsorption of Trichoderma reesei CBHI cellulase on silanized silica.

Adsorption kinetics and surfactant-mediated elution of Trichoderma reesei CBHI cellulase were recorded in situ, at hydrophobic, silanized silica. Experiments were performed at different solution concentrations, ranging from 0.001 to 0.98 mg/mL. Adsorbed enzyme was partially elutable upon rinsing, with the amount of adsorbed mass remaining being highest at intermediate concentrations. In addition, the resistance to elution with buffer was generally lower at higher concentrations, and the resistance to elution with surfactant was generally lower at intermediate concentrations. These observations are tentatively explained with reference to a mechanism allowing for adsorption of associated monomers of CBHI as well as free monomers.

Adsorption↗
PubMed2000

Adsorption of thermomonospora fusca E(5) cellulase on silanized silica.

The adsorption kinetics and dodeceyltrimethylammonium-bromide-mediated elution of Thermomonospora fusca E(5) cellulase were recorded in situ, at hydrophobic, silanized silica. Experiments were performed at different solution concentrations, ranging from 0.001 to 0.70 mg/mL. Plateau values of adsorbed mass generally increased with increasing solution concentration, with the adsorbed layer being only partially eluted by buffer. Treatment with surfactant removed more of the adsorbed enzyme in each case, with the remaining adsorbed mass varying little among experiments. Adsorption of E(5) into this nonremovable state was suggested to occur early in the adsorption process and continue until some critical surface concentration was reached. Beyond this critical value of adsorbed mass, adsorption progressed with the protein adopting more loosely bound states. Adsorption kinetic data were interpreted with reference to an adsorption mechanism allowing for irreversible adsorption into two dissimilar states. These states were distinguished by differences in occupied interfacial area, and binding strength, presumably a result of differences in structure. Comparison of the data to the kinetic model based on this mechanism showed that the fraction of adsorbed molecules present in the more tightly bound state decreased as adsorption occurred from solutions of increasing concentration. However, the absolute values of more tightly bound molecules were less dependent on adsorption conditions.

Actinomycetales↗
PubMed2000

Can the criminal law ever be therapeutic?

This paper addresses the question of whether criminal law, especially in its sentencing and penological aspects, can be adjusted in its workings to incorporate the perspective of therapeutic jurisprudence. A conceptual framework developed by Wexler, Winick, and their colleagues is employed to provide a basis for reflection on the operation and impact of sentencing processes. Of considerable importance in this exercise is a mounting volume of evidence concerning the outcomes of work with adjudicated offenders, which illustrates the potential of psycho-educational, behavioral-cognitive skills-training, and therapeutic programs for reduction of recidivism. Such intervention programs are currently offered within the limits set by, but are not intrinsic components of, judicial decisions. The psycho-legal implications of these findings are discussed and some possibilities surveyed for tentative exploration of actively therapeutic departures within crimino-legal decision-making.

Cognitive Behavioral Therapy↗
PubMed2000

Hoptel equalizes length of stay for homeless and domiciled inpatients.

BACKGROUND: There is growing evidence that homeless individuals have longer inpatient lengths of stay with significantly higher medical costs than domiciled individuals. We compared adjusted mean lengths of stay among domiciled patients and homeless patients discharged to a hospital hotel (hoptel). Because the hoptel allowed homeless patients to be discharged when medically indicated, we hypothesized no significant differences in lengths of stay between the 2 groups after adjustment for severity of illness. METHODS: Demographic, diagnosis, and length of stay data were obtained for all patients discharged from all inpatient wards at a large, urban Veterans Affairs Medical Center during the first 32 months of hoptel operation (1996 through 1998). Adjusted mean lengths of stay for domiciled patients and homeless patients discharged to the hoptel were compared. ANCOVA was used to adjust for demographic characteristics (age, income, race/ethnicity), diagnosis-related group (DRG), principal diagnosis, and substance abuse comorbidity. Three types of hospitalizations were analyzed on the basis of major DRG categories: general medical, psychiatric, and all hospitalizations. RESULTS: No significant differences were found in adjusted mean lengths of stay between domiciled patients and homeless patients discharged to the hoptel. Homeless hoptel patients stayed an average 0.7, 0.3, and 0.4 days longer than domiciled patients for all, general medical, and psychiatric hospitalizations (P = 0.504, 0.627, and 0.839), respectively. CONCLUSIONS: These data suggest that hoptels may help equalize inpatient lengths of stay among domiciled and homeless patients discharged to a hoptel. Public health care systems seeking innovative ways of reducing inpatient lengths of stay among homeless patients ought to consider establishing hoptels.

Aftercare↗
PubMed2000

Reducing psychiatric hospitalization among mentally ill veterans living in board-and-care homes.

OBJECTIVE: The effectiveness of a community-based case management program at the Veterans Affairs West Los Angeles Healthcare Center in reducing hospital readmission of mentally ill veterans living in privately operated board-and-care homes was evaluated. METHODS: A retrospective cohort design was used. The sample consisted of 321 patients identified by hospital records as living in one of 24 board-and-care homes in the Los Angeles area that were approved by the community residential care program. A total of 214 subjects who received monthly home visits from case managers (program group) were compared with 107 subjects who did not receive monthly home visits (comparison group). The median number of psychiatric bed-days used was calculated for the two years before and after follow-up. The number of days from the start of follow-up to the first psychiatric hospitalization was also calculated. RESULTS: Among subjects in the program group, the median number of psychiatric bed-days used decreased significantly, from 59 days to 50 days. No significant change in the median number was observed for comparison subjects. Comparison subjects were rehospitalized 1.7 times more often than program subjects. Overall, program subjects under age 62 (younger subjects) were rehospitalized 2.5 times more often than older subjects. In the program group, those who had received home visits for more than two years were hospitalized three times more often than those who had received visits for less than two years, and younger subjects were rehospitalized 1.8 times more often than older subjects. CONCLUSIONS: The findings suggest that home visits conducted by case managers in a community residential care program helped reduce psychiatric hospitalization among veteran patients living in privately operated board-and-care homes.

Female↗
PubMed2000

Sex steroids and the endothelium.

Gonadal steroids clearly influence the course of atherosclerotic cardiovascular disease in women. This observation has suggested that these hormones have beneficial effects on the physiology of the vascular wall. Increased arterial vascular caliber after estrogen treatment, decreased lipid levels in subjects receiving hormone replacement therapy, and the markedly decreased extent of atherosclerotic plaque formation in young women as compared with young men support a cardioprotective effect of ovarian steroids. Generally, it appears that the effects of 17beta-estradiol are particularly beneficial, and the mechanism of action is targeted largely to the endothelial cell. This review describes the evidence for positive effects of estrogens on endothelial cell biology and considers potential mechanisms for estrogen actions on endothelial cell signal transduction.

Animals↗
PubMed1999

Activity losses among T4 lysozyme charge variants after adsorption to colloidal silica.

Enzyme structure and function depend to some extent on enzyme net charge and charge location. Altering the charge of even a single residue may affect the interaction between enzyme and substrate such that all catalytic activity is lost. In this study we investigated the effect of net charge and charge location on the enzymatic activity of synthetic mutants of bacteriophage T4 lysozyme in the presence of colloidal silica. Enzymatic activity decreased upon adsorption, and these changes were variant-specific. Results were interpreted with reference to differences in adsorbed enzyme structure and orientation, and electrostatic effects. By exploring the effects of enzyme charge on adsorption, it may be possible to gain a better understanding of how enzyme structure influences adsorption and function at an interface.

Adsorption↗
PubMed1999

A Mechanistic Approach to Modeling Single Protein Adsorption at Solid-Water Interfaces.

A kinetic model for single component protein adsorption which can be readily extended to adsorption from multi-protein solutions was developed, and used to simulate adsorption of site-directed, structural stability mutants of bacteriophage T4 lysozyme. The model allows for two different adsorbed "states," distinguished by different binding strengths and different occupied areas. The presence of an increasing energy barrier to adsorption was incorporated into the model by formulating the adsorption rate constants as functions of time. Numerical analysis was performed using the Marquardt method. Estimated model parameters were consistent with the effect of structural stability on adsorption. In particular, kinetic parameters were such that adsorption into the more tightly bound, conformationally altered state was favored by less stable variants. Copyright 1999 Academic Press.

Journal Article↗