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Biomedical subjects

M A Patterson

Publications and source records attributed to M A Patterson.

At least 19 recordsLinked to original sources
PubMed2001

Lessons learned in adopting endovascular techniques for treating abdominal aortic aneurysm.

HYPOTHESIS: Endovascular exclusion of abdominal aortic and common iliac aneurysms can be performed safely, and in the short term represents a feasible alternative to traditional, open aneurysm repair. PATIENTS AND METHODS: Forty-one patients were treated with endovascular grafts for 39 abdominal aortic and 2 common iliac artery aneurysms. RESULTS: All devices were successfully deployed. The size of the abdominal aortic aneurysms varied from 4.9 to 11.9 cm (average, 6.13 cm). The median procedure time was 195 minutes. There was one iliac artery rupture, which required celiotomy for repair. The hospital stay varied from 2 to 39 days (average, 6.7 days). The perioperative mortality rate was 2.4%. Sixteen patients (39%) had groin wound complications. Ten patients (24%) had evidence of contrast (endoleak) within the aneurysm sac on completion of the procedure. There were no obvious direct leaks from either the point of proximal or distal fixation. Seven of these endoleaks have resolved spontaneously. Two patients required additional procedures in the postoperative period to treat endoleak. The final patient has evidence of persistent endoleak on 3-month surveillance computed tomography scan. Major late problems occurred in 3 patients. CONCLUSION: Patients with large abdominal aortic aneurysms and considerable cardiac comorbidity can safely undergo endovascular aneurysm repair. Femoral groin wound complications resulting in prolonged hospitalization remain the major cause of perioperative morbidity. In contradistinction to open aneurysm repair, long-term surveillance is essential to detect migration of the device and identify flow within the residual aneurysm sac-complications that could lead to aneurysm rupture following endovascular repair.

Aged↗
PubMed2001

Shear force regulates matrix metalloproteinase activity in human saphenous vein organ culture.

BACKGROUND: Development of vein graft intimal hyperplasia has been related both to shear force and to the activity of matrix metalloproteinases (MMPs). Little data are available regarding the effects of shear on MMP expression and activity. The aim of this study was to examine the relationship among shear force, metalloproteinase activity, and intimal thickening in human saphenous vein segments maintained in organ culture. MATERIALS AND METHODS: Segments of human saphenous vein were cultured under static conditions, or perfused under low-flow and high-flow conditions in a perfusion apparatus for 7 days. Metalloproteinase levels and activities were measured using ELISA and substrate gel zymography, respectively. Intimal thickening was determined by morphometric analysis. Results were compared with control vein tissue, which was not subjected to organ culture, using a one-way ANOVA. RESULTS: A 13% increase in proteolytic activity was noted on substrate gel zymography at 68-72 kDa in high-flow vein tissue. The protein content of MMP-2, MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and TIMP-2 was increased in high-flow vein tissue by 21%, 126%, more than 100-fold, and 86%, respectively. In culture media bathing the outside of the vein, TIMP-2 was increased in high-flow specimens, while TIMP-1 was inversely related to flow rate. Intimal thickening was directly related to flow rates, and was progressively increased in the low-flow and high-flow groups by 3-fold and 4-fold, respectively. CONCLUSIONS: Metalloproteinase levels in human saphenous vein cultures are related to shear force. MMP levels and activity correlate with the degree of intimal thickening. This model may provide a valuable tool for the analysis of physical forces and their influence on intimal thickening in human saphenous vein.

Enzyme-Linked Immunosorbent Assay↗
PubMed2000

Transforming practice organizations to foster lifelong learning and commitment to medical professionalism.

Practice organizations will increasingly engage in activities that are the functional equivalents of continuing medical education. The authors maintain that if these activities are properly structured within practice organizations, they can become powerful engines of socialization to enhance physicians' lifelong learning and commitment to medical professionalism. They propose that this promise can be realized if new or reformed practice organizations combine education and service delivery and institutionalize processes of individual and collective reflection. The resulting "institutions of reflective practice" would be ones of collegial, experiential, reflective lifelong learning concerning the technical and normative aspects of medical work. They would extend recent methods of medical education such as problem-based learning into the practice setting and draw on extant methods used in complex organizations to maximize the advantages and minimize the disadvantages that practice organizations typically present for adult learning. As such, these institutions would balance the potentially conflicting organizational needs for, on the one hand, (1) self-direction, risk taking, and creativity; (2) specialization; and (3) collegiality; and, on the other hand, (4) organizational structure, (5) coordination of division of labor, and (6) hierarchy. Overall, this institutionalization of reflective practice would enrich practice with education and education with practice, and accomplish the ideals of what the authors call "responsive medical professionalism." The medical profession would both contribute and be responsive to social values, and medical work would be valued intrinsically and as central to practitioners' self-identity and as a contribution to the public good.

Adult↗
PubMed1999

Combined blunt cardiac and pericardial rupture: review of the literature and report of a new diagnostic algorithm.

The spectrum of blunt cardiac injury varies from the asymptomatic cardiac concussion to the immediately fatal cardiac rupture. Although the majority of victims sustaining blunt cardiac rupture die before receiving medical attention, some survive to evaluation. The diagnosis of cardiac rupture, if established, typically results from the signs and symptoms of pericardial tamponade. However, some patients may have remarkably few signs and symptoms suggestive of cardiac injury and represent a significant diagnostic challenge. We provide two cases of cardiac rupture in which the diagnosis was delayed by the presence of an associated pericardial tear with decompression into the mediastinum and pleural space. In neither of the cases did existing institutional algorithms for blunt cardiac injury assist in establishing the diagnosis before the acute demise of the patient. The presence of a coexisting pericardial injury in these patients with blunt cardiac rupture obscured the diagnosis, leading to the deaths of these patients. A discussion of these two cases and review of the literature is provided with recommendations for diagnostic algorithms in patients sustaining blunt thoracic trauma with possible cardiac and pericardial injury.

Accidents, Traffic↗
PubMed1998

Dengue surveillance in Texas, 1995.

Dengue epidemics have been occurring in the Caribbean and Central and South America, including Mexico. In 1995, the proximity of these epidemics increased the possibility of cases occurring in Texas. In response, medical and community educational materials were distributed and active surveillance for dengue cases was initiated. By the end of the year, sera from more than 360 patients were tested for anti-dengue antibody. Twenty-nine cases were detected statewide; seven cases in southern Texas were locally acquired.

Adolescent↗
PubMed1996

A monoclonal antibody to human macrophage gangliosides inhibits macrophage migration.

Gangliosides have diverse immunoregulatory properties. The gangliosides endogenous to macrophages may have immunoregulatory properties that distinguish them from other gangliosides. Gangliosides have been indirectly implicated in macrophage migration as putative cell surface receptors for migration inhibitory factor (MIF). In this study, a monoclonal antibody to human macrophage gangliosides (antibody 25F4) was developed and characterized. This is the first report of the development of monoclonal antibodies to gangliosides of macrophages of any species. Thin-layer chromatographic immunostaining indicated that antibody 25F4 recognized major gangliosides of human macrophages but did not recognized those previously identified as containing fucose. Immunofluorescent surface labeling of viable human macrophages indicated that antibody 25F4 recognized a surface-accessible epitope, present on all cells, and that this was abolished with lipid depletion of macrophage membranes. This epitope was not present on several human nonmacrophage cells. Finally, human macrophages pretreated with antibody 25F4 demonstrated striking inhibition of migration of an agarose droplet assay, whereas an irrelevant monoclonal antibody or monoclonal antibodies to nonganglioside surface epitopes of human macrophages had no effect on migration. Migration inhibition occurred even though antibody 25F4 was removed from the extracellular milieu and was not due to formation of cellular aggregates. These studies support a role for human macrophage gangliosides in macrophage migration.

Antibodies, Monoclonal↗
PubMed1996

Electrostimulation: addiction treatment for the coming millennium.

At a period of fundamental review of the health care system, it is timely to re-assess one of medicine's most intractable problems--the treatment of addictions. The apparently insoluble dilemmas posed by the acute and chronic withdrawal syndromes underlie universally high drop-out and relapse rates. In a decade of HIV and AIDS infection, poly-substance addiction, potent street drugs, and ossified treatment strategies, it is urgent that policy formulators investigate seriously a flexible system of non-pharmacological transcranial electrostimulation treatment, based on its record of rapid, safe, and cost-effective detoxification in several countries, as one innovative contribution to the challenges presented by addiction in the 1990s. This is a brief report of the introduction of NeuroElectric Therapy (NET) into Germany, describing the responses of the first 22 cases. The daily progress of a heroin addict and a methadone addict are detailed: both were treated as outpatients for 8 hours daily, for 7 and 10 days respectively.

Electric Stimulation Therapy↗
PubMed1996

Outcomes of residential treatment of substance abuse in hospital- and community-based programs.

OBJECTIVE: The study sought to determine whether inpatient readmission rates differed for patients with substance use disorders who were treated in either hospital-based or community-based transitional residential care. Length of residential care and intensity of outpatient mental health aftercare were examined as predictors of readmission. METHODS: Department of Veterans Affairs nationwide databases were used to document readmissions at one- and two-year intervals for male inpatients treated for substance use disorders who were discharged either to hospital-based (N = 2,190) or community-based (N = 4,490) residential care. Patients with and without concomitant psychiatric diagnoses were identified. RESULTS: Patients treated in community-based residential programs had lower one- and two-year readmission rates than patients who received hospital-based residential care. Longer episodes of residential care and more outpatient mental health care were also associated with lower readmission rates. Among patients with concomitant psychiatric disorders, those in hospital-based care benefited more from longer episodes of residential care and more intensive outpatient mental health aftercare. Residential care, longer episodes of care, and more outpatient mental health care were independent predictors of lower one- and two-year readmission rates after patient-based risk factors were controlled. CONCLUSIONS: The findings highlight the value of providing adequate amounts of residential and outpatient care for patients in substance abuse treatment, especially patients with concomitant psychiatric disorders.

Adult↗
PubMed1995

n-Butyrate mediation of ganglioside expression of human and murine cancer cells demonstrates relative cell specificity.

1. n-Butyrate, a short chain fatty acid produced by colonic fermentation, induces differentiation in human neoplastic cell lines, and reduces expression in vitro of a sialyltransferase that glycosylates N-linked glycoproteins in hepatoblastoma cells. Gangliosides are amphipathic, sialylated glycosphingolipids that undergo profound changes in many transformed cells and may protect neoplastic cells from host immune surveillance. Colonic mucosal cells are exposed to luminal short-chain fatty acid concentrations of up to 80 mmol/l, and there is some evidence that short-chain fatty acids may alter ganglioside expression in colon cancer cells. 2. Because of the importance of gangliosides in cancer pathogenesis, we investigated the effects of n-butyrate on ganglioside expression of colonic (human and murine) and non-colonic cancer cells. 3. Three separate colon cancer cell lines (LS174T, T84 and MCA-38), when butyrate treated, demonstrated striking amplification of specific individual gangliosides. However, the total lipid-bound sialic acid content of gangliosides of butyrate-treated LS174T cells diminished. In contrast to earlier reports, n-butyrate did not mediate expression of all gangliosides and specifically did not mediate expression of GM3. This effect persisted even after removal of butyrate. 4. In contrast, exposure of extracolonic cells to butyrate, including cervical cancer (HeLa) and laryngeal cancer (HEp-2) cell lines in this study and hepatoblastoma cells (Hep G2) in our previous work, caused no detectable changes in ganglioside expression. 5. In conclusion, our results indicate a relative tissue specificity of butyrate-mediated alterations in ganglioside expression that is not universal but is limited to specific gangliosides.

Animals↗
PubMed1989

Services for maintaining independence.

Providing a range of health-related services may be necessary for some elderly to remain in independent living environments. Wellness Centers can identify those at risk for disease, promote self-care techniques, and assess the need for other health services. Entrepreneural nurses have the opportunity to seek out congregate housing sites with large aging populations to create ways of promoting healthy lifestyles and a higher quality of life for older persons. A holistic approach to health care helps the elderly to manage chronic disease, maintain high levels of functioning, and promote self-responsibility.

Adult↗
PubMed1988

Hydrogen peroxide-mediated inhibition of T-cell response to mitogens is a result of direct action on T cells.

Hydrogen peroxide, a reactive oxygen intermediate produced by activated neutrophils, has been shown to inhibit the response of human T lymphocytes to mitogens and alloantigens. Since hydrogen peroxide is known to react with iron and to induce lipid peroxidation, we compared the effects of hydrogen peroxide and a lipid peroxidation product, malondialdehyde, on the response of human peripheral blood mononuclear cells to T-cell mitogens. Peripheral blood mononuclear cells pretreated with 1 mmol/L of malondialdehyde, washed, and resuspended in fresh medium exhibited no inhibition of phytohemagglutinin responsiveness. Peripheral blood mononuclear cells treated in the same manner but with 200 mumol/L of hydrogen peroxide were inhibited by more than 95%. The addition of ferric edetate did not alter the inhibitory effects of 50 to 100 mumol/L of hydrogen peroxide, nor did the addition of deferoxamine, an iron chelator. These studies suggest that exogenous lipid peroxidation does not affect lymphocyte activation but that hydrogen peroxide has a direct inhibitory effect. Although monocytes are necessary for T-cell mitogenic responses, the effect of hydrogen peroxide was found to be directed at T lymphocytes. Exposure of T cells to a single dose of 200 mumol/L of hydrogen peroxide resulted in more than 71% suppression of the proliferative response measured 48 hours later, but the effect was spontaneously reversed by 72 to 96 hours. Repeated exposure of the cells to hydrogen peroxide resulted in continued inhibition of the proliferative response. These findings suggest that hydrogen peroxide produced by inflammatory phagocytic cells might be capable of suppressing the immune response of nearby T lymphocytes.

Deferoxamine↗
PubMed1983

Free radical metabolism of hydralazine. Binding and degradation of nucleic acids.

The binding of hydralazine, a hydrazine-containing hypotensive drug, to nucleic acids has been studied. Binding of this drug to biopolymers was assayed using spin-trapping techniques in the presence of various metal ions, which produce free radical intermediates from hydralazine [B. K. Sinha and A. G. Motten, Biochem, biophys. Res. Commun. 105, 1044 (1982)]. Some interaction was detected with the single-stranded nucleic acids. Hydralazine binds strongly to the native DNA, most likely by intercalation of the drug into DNA bases. In the presence of nucleic acids and metal ions, hydralazine stimulated the production of OH(.) radicals which was inversely proportional to the degree of binding. Aldehyde formation in DNA was also induced by hydralazine which was stimulated by superoxide dismutase and inhibited by catalase.

Aldehydes↗
PubMed1982

Periplasmic enzymes in Bdellovibrio bacteriovorus and Bdellovibrio stolpii.

When cells of either Bdellovibrio bacteriovorus 109J or Bdellovibrio stolpii UKi2 were subjected to osmotic shock by treatment with sucrose-EDTA and MgCl2 solutions, only trace amounts of proteins or enzyme activities were released into the shock fluid. In contrast, when nongrowing cells were converted to motile, osmotically stable, peptidoglycan-free spheroplasts by penicillin treatment, numerous proteins were released into the suspending fluid. For both species, this suspending fluid contained substantial levels of 5'-nucleotidase, purine phosphorylase, and deoxyribose-phosphate aldolase. Penicillin treatment also released aminoendopeptidase N from B. bacteriovorus, but not from B. stolpii. Penicillin treatment did not cause release of cytoplasmic enzymes such as malate dehydrogenase. The data indicated that bdellovibrios possess periplasmic enzymes or peripheral enzymes associated with the cell wall complex. During intraperiplasmic bdellovibrio growth, periplasmic and cytoplasmic enzymes of the Escherichia coli substrate cell were not released upon formation of the spherical bdelloplast during bdellovibrio penetration. Most of the E. coli enzymes were retained within the bdelloplast until later in the growth cycle, when they became inactivated or released into the suspending buffer or both.

5'-Nucleotidase↗