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Biomedical subjects

K Schumacher

Publications and source records attributed to K Schumacher.

At least 19 recordsLinked to original sources
PubMed2005

[Effects of distress and coping on quality of life in HIV-positive patients: results of a longitudinal study].

Preserving health-related quality of life (QOL) is an important approach with HIV-positive patients. In a longitudinal study over 3 years, with three measurements each 18 months, we examined 56 of these patients for the influence of distress and coping (assessed by interviews) on physical, cognitive-emotional, and social QOL (using the SEL questionnaire). The patients were 32.9 years old on average, with 28.3 months since diagnosis. Seventy percent were male, 82% asymptomatic, 14% with ARC, and 4% with AIDS. Forty-five percent had been infected by homosexual intercourse, 14% by heterosexual intercourse, and 41% by iv drug abuse. The patients reported significantly worse physical and cognitive-emotional QOL than healthy subjects. Those HIV-positive persons with great distress showed significantly lower QOL scores. Multiple analyses of regression showed evasive-regressive coping at the T1, T2, and T3 levels as negative predictors, vs active, problem-focused coping as a positive predictor for nearly all QOL parameters at T3. HIV-positive patients with ARC or AIDS reported more physical complaints and lower physical QOL than asymptomatic persons. Physicians should suggest psychosocial support to patients with poor QOL scores.

Adaptation, Psychological↗
PubMed2004

Cocaine- and amphetamine-regulated transcript stimulates colonic motility via central CRF receptor activation and peripheral cholinergic pathways in fed, conscious rats.

Many neuropeptides participating in the hypothalamic control of feeding behaviour and satiety have been shown to be additionally involved in the autonomic control of gastrointestinal (GI) functions. Recently, the neuropeptide cocaine- and amphetamine-regulated transcript (CART) has been indicated to function as an anorectic substance in the brain. In the present study we examine the hypothesis that CART is involved in the modulation of GI motility. Colonic transit time was measured after peripheral and central injection of CART in fed and freely moving Sprague-Dawley rats. Intracerebroventricular injection of synthetic CART (55-102) (190 pmol and 1.9 nmol per 10 microL and saline controls) decreased the colonic transit time of conscious rats up to 46%. In contrast, i.p. injection of CART (55-102) (1.9 nmol and 19 nmol kg(-1) BW and saline controls) had no effect on colonic motility. Central administration of a CRF receptor antagonist (2.8 nmol) prior to central CART administration antagonized the CART-induced stimulation of colonic transit. Pretreatment with the peripherally acting cholinergic antagonist atropin methyl nitrate (0.1 mg kg(-1) i.p.) blocked the stimulatory CART effect on colonic motor function. The results suggest that CART acts in the central nervous system to modulate behavioural motor function via a central CRF receptor-dependent mechanism and peripheral cholinergic pathways.

Animals↗
PubMed2003

Characterization of micro-fibers at the interface between the renal collecting duct ampulla and the cap condensate.

The development of renal histo-architecture substantially depends on the three-dimensional extension of the collecting duct (CD) ampulla, since under its influence, nephron induction takes place in the surrounding mesenchyme. Recently, micro-fibers were detected by soybean agglutinin (SBA), which line from the basal aspect of each CD ampulla through the mesenchyme towards the organ capsule in embryonic kidney. Their unique distribution suggests that they may play an important role in the control of CD ampulla growth and in forming the renal stem cell niche. A profound analysis of interstitial proteins between the CD ampulla and the nephrogenic mesenchyme is lacking. Consequently, the goal of the current investigation was to colocalize the micro-fibers detected by SBA with interstitial proteins. For this reason a detailed cell biological analysis of extracellular molecules at this site was carried out. Double labeling showed that the micro-fibers do not correspond to known collagens and other extracellular matrix molecules such as agrin, versican or MMP-9. In addition, it could be demonstrated that the micro-fibers do not contain epithelial or mesenchymal cell elements. Furthermore, two-dimensional electrophoresis with subsequent Western blotting yielded two different amino acid sequences (1: GHYADPTSPR; 2: NNGCCSSDYHA) obtained from SBA-labeled protein spots. Both amino acid sequences could not be assigned to known rodent proteins. The findings suggest that the SBA-labeled micro-fibers represent a new type of extracellular structure between the CD ampulla, the mesenchyme and the organ capsule.

Animals↗
PubMed2001

Lack of adherence with the analgesic regimen: a significant barrier to effective cancer pain management.

PURPOSE: To evaluate oncology outpatients' level of adherence to their analgesic regimen during a 5-week period. PATIENTS AND METHODS: A random sample of 65 adult oncology outpatients with a Karnofsky performance status score of >or= 50, an average pain intensity score of >or= 2.5, and radiographic evidence of bone metastasis were recruited for this longitudinal study from seven outpatient settings. On a daily basis, patients rated their level of pain intensity and recorded pain medication intake. Adherence rates for opioid analgesics prescribed on an around-the-clock (ATC) and on an as-needed (PRN) basis were calculated on a weekly basis. RESULTS: Overall adherence rates for ATC opioid analgesics ranged from 84.5% to 90.8% and, for PRN analgesics, from 22.2% to 26.6%. No significant differences over time were found in either of these adherence rates. CONCLUSION: One factor that seems to contribute to ineffective cancer pain management is poor adherence to the analgesic regimen.

Analgesics↗
PubMed2001

Extremozymes for improving wool properties.

The project 'EXTRETEX' funded by the German Federal Foundation Environment (DBU, Osnabrück, Germany) aims at the improvement of wool properties dyeability, handle, felting behaviour and degree of whiteness by means of enzymes derived from extremophilic micro-organisms. In this paper the effects of a commercial thermo- and alkalistable protease on wool with regard to the degree of whiteness, the dyeability and the felting behaviour are presented. A method to treat wool top and wool fabric was developed on a laboratory scale in which the protease was integrated into the pre-washing step of a dyeing process. This treatment method was than scaled up and tested on an industrial winch beck for fabric. With this method-the addition of enzyme in the pre-washing step-the degree of whiteness is generally enhanced. Dyeing untreated and the enzyme-treated wool with Lanasol Blue 8G leads to an improved dyestuff uptake and a distinctive difference in the colour shade for the latter. Microscopy pictures of fibre cross-sections of these samples display a more even distribution of the dyestuff and a better penetration in the enzyme-treated wool fibres but the colour fastness of the enzyme-treated wool is decreased. Though the felting behaviour of the protease treated wool is significantly improved the felting tendency is still too high for an antifelting finish. An increased damage of the enzyme-treated wool in comparison with the untreated one was not observed.

Animals↗
PubMed2001

A defined range of guard cell calcium oscillation parameters encodes stomatal movements.

Oscillations in cytosolic calcium concentration ([Ca2+]cyt) are central regulators of signal transduction cascades, although the roles of individual [Ca2+]cyt oscillation parameters in regulating downstream physiological responses remain largely unknown. In plants, guard cells integrate environmental and endogenous signals to regulate the aperture of stomatal pores and [Ca2+]cyt oscillations are a fundamental component of stomatal closure. Here we systematically vary [Ca2+]cyt oscillation parameters in Arabidopsis guard cells using a 'calcium clamp' and show that [Ca2+]cyt controls stomatal closure by two mechanisms. Short-term 'calcium-reactive' closure occurred rapidly when [Ca2+]cyt was elevated, whereas the degree of long-term steady-state closure was 'calcium programmed' by [Ca2+]cyt oscillations within a defined range of frequency, transient number, duration and amplitude. Furthermore, in guard cells of the gca2 mutant, [Ca2+]cyt oscillations induced by abscisic acid and extracellular calcium had increased frequencies and reduced transient duration, and steady-state stomatal closure was abolished. Experimentally imposing [Ca2+]cyt oscillations with parameters that elicited closure in the wild type restored long-term closure in gca2 stomata. These data show that a defined window of guard cell [Ca2+]cyt oscillation parameters programs changes in steady-state stomatal aperture.

Abscisic Acid↗
PubMed2001

Prognostic significance of activated CD8(+) T cell infiltrations within esophageal carcinomas.

The purpose of this study was to explore whether there is a linkage between the infiltration of CD8(+) T cells and the risk of death from esophageal cancer. Cases of 70 consecutive patients in whom esophageal squamous cell carcinomas ( n = 33) or adenocarcinomas (n = 37) were R0-resected between 1993 and 1999 were reviewed. The presence of activated CD8(+) T cells was evaluated by quantitative real-time PCR and immunohistochemistry and compared to clinical and pathological stages. The primary end point analyzed was overall survival, and a multivariate analysis was performed to distinguish any factors conferring an improved survivorship. Intratumoral (i.t.) CD8(+) T cells accumulating within the epithelial complexes were detected in 11 of all (16%) cases: in 9 of 25 (36%) patients with Union Internationale Contrele Cancer stage I or II versus 2 of 45 (4%) patients with Union Internationale Contrele Cancer stage III or IV (P = 0.001). Intratumoral CD8(+) T cell infiltrations showed proliferative activity and also IFN-gamma secretion. The presence of i.t. CD8(+) T cell infiltration more than peritumoral infiltration was associated with a good prognosis in both squamous cell and adenocarcinomas. Multivariate analysis showed that i.t. CD8(+) T cell infiltration was an independent prognostic factor (hazard ratio, 0.5; P = 0.0004) indicating favorable outcome. In conclusion, the presence of CD8(+) T cell infiltration in esophageal carcinomas is a favorable prognostic factor that should have diagnostic and therapeutic implications.

Adenocarcinoma↗
PubMed2001

Moderate hypothermia during cardiopulmonary bypass reduces myocardial cell damage and myocardial cell death related to cardiac surgery.

OBJECTIVES: The goal of this study was to test the hypothesis that moderate hypothermia during cardiopulmonary bypass (CPB) provides myocardial protection by enhancing intra-myocardial anti-inflammatory cytokine balance. BACKGROUND: Moderate hypothermia during experimental CPB stimulates production of interleukin-10 (IL10) and blunts release of tumor necrosis factor-alpha (TNFalpha). METHODS: Twelve young pigs were assigned to a temperature (T degrees ) regimen during CPB: moderate hypothermia (T degrees : 28 degrees C; n = 6) and normothermia (T degrees : 37 degrees C; n = 6). Intra-myocardial TNFalpha- and IL10-messenger RNA were detected by competitive reverse transcriptase polymerase chain reaction and quantification of cytokine synthesis by Western blot. Levels of cardiac troponin I (cTnI) in cardiac lymph and in arterial and coronary venous blood were examined during and after CPB. Myocardial cell damage was assessed by histologic and ultrastructural anomalies of tissue probes taken 6 h after CPB. RESULTS: Synthesis of IL10 was significantly higher, while that of TNFalpha was significantly lower, in pigs that were in moderate hypothermia during surgery than in the others. In contrast with normothermia, moderate hypothermia was also associated with significantly lower cumulative cardiac lymphatic flow during and after CPB, significantly lower lymphatic cTnI concentrations after CPB, significantly lower percentages of myocardial cell necrosis and a significantly lower score of ultrastructural anomalies of myocardial cells. While the percentage of apoptotic cells was not different between groups, the apoptosis/necrosis ratio tended to be higher in animals that were in moderate hypothermia during surgery. In all animals, TNFalpha synthesis correlated positively while IL10 production correlated negatively with necrosis and total cell death, respectively. CONCLUSIONS: Our results suggest that moderate hypothermia during CPB provides myocardial protection by enhancing intra-myocardial anti-inflammatory cytokine balance.

Animals↗
PubMed2001

Influence of temperature during cardiopulmonary bypass on leukocyte activation, cytokine balance, and post-operative organ damage.

This study examined the hypothesis that core temperature (T(o)) during cardiopulmonary bypass (CPB) influences the perioperative systemic inflammatory response and post-operative organ damage. Twenty-four pigs were assigned to a T(o) regimen during CPB: normothermia (T(o) 37 degrees C; n = 8), moderate hypothermia (T(o) 28 degrees C; n = 8), or deep hypothermia (T(o) 20 degrees C; n = 8). Perioperative leukocyte activation, endotoxin release, and production of tumor necrosis factor-alpha (TNFalpha) and interleukin-10 (IL10) were examined with regard to post-operative organ damage, which was scored at histological examination of tissue probes of heart, lungs, liver, kidney, and ileum, taken 6 h after CPB. Total blood leukocyte count and TNFalpha plasma levels during CPB were significantly lower and IL10 levels were significantly higher in the moderate hypothermic group than in both other groups. Elastase activity, leukotriene B4-, and endotoxin levels were not affected by T(o) regimen. Moderate hypothermia was associated with the lowest histological organ damage score and normothermia with the highest. In all animals organ damage score for heart, lungs, and kidneys correlated significantly with TNFalpha levels at the end of CPB. Our data demonstrate a clear relationship between TNFalpha production during cardiac operations and post-operative multiple-organ damage. Moderate hypothermia, by stimulating IL10 synthesis and suppressing TNFalpha production during CPB, might provide organ protection.

Animals↗
PubMed2001

Comparative sequence analysis reveals extensive microcolinearity in the lateral suppressor regions of the tomato, Arabidopsis, and Capsella genomes.

A 57-kb region of tomato chromosome 7 harboring five different genes was compared with the sequence of the Arabidopsis genome to search for microsynteny between the genomes of these two species. For all five genes, homologous sequences could be identified in a 30-kb region located on Arabidopsis chromosome 1. Only two inversion events distinguish the arrangement of the five genes in tomato from that in Arabidopsis. Inversions were not detected when the arrangement of the five Arabidopsis genes was compared with the arrangement in the orthologous region of Capsella, a plant closely related to Arabidopsis. These results provide evidence for microcolinearity between closely and distantly related dicotyledonous species. The degree of microcolinearity found can be exploited to localize orthologous genes in Arabidopsis and tomato in an unambiguous way.

Brassicaceae↗
PubMed2001

Long term culture of epithelia in a continuous fluid gradient for biomaterial testing and tissue engineering.

Epithelia perform barrier functions being exposed to different fluids on the luminal and basal side. For long-term testing of new biomaterials as artificial basement membrane substitutes, it is important to simulate this fluid gradient. Individually-selected biomaterials can be placed in tissue carriers and in gradient containers, where different media are superfused. Epithelia growing on the tissue carriers form a physiological barrier during the whole culture period. Frequently however, pressure differences between the luminal and basal compartments occur. This is caused by a unilateral accumulation of gas bubbles in the container compartments resulting in tissue damage. Consequently, the occurence of gas bubbles has to be minimized. Air bubbles in the perfusion culture medium preferentially accumulate at sites where different materials come into contact. The first development is new screw caps for media bottles, specifically designed to allow fluid contact with only the tube and not the cap material. The second development is the separation of remaining gas bubbles from the liquid phase in the medium using newly-developed gas expander modules. By the application of these new tools, the yield of embryonic renal collecting duct epithelia with intact barrier function on a fragile natural support material can be significantly increased compared to earlier experiments.

Air↗
PubMed2000

High concentration of soluble HLA-DR in the synovial fluid: generation and significance in "rheumatoid-like" inflammatory joint diseases.

In the search for its role in inflammatory joint diseases, soluble HLA-DR (sHLA-DR) was quantitated in 72 synovial fluids (SF) by a newly established immunoenzyme assay. Unlike other soluble receptors which accumulated only moderately (sCD25, sCD4) or negligibly (sHLA class I, sCD8) in the SF, SF sHLA-DR levels exceeded serum levels by up to 3 orders of magnitude and varied disease dependently from "control" values (traumatic synovitis and osteoarthritis: 9.9 +/- 6.1 ng/ml). Clear-cut different SF sHLA-DR values in HLA-DR-associated "rheumatoid-like" (136.5 +/- 130.0 ng/ml) vs HLA-B27-associated "spondylarthropathy-like" arthritic forms (28.4 +/- 29.1 ng/ml) were most significant comparing oligoarticular juvenile chronic arthritis type I (147.6 +/- 112.6 ng/ml) and type II (3.3 +/- 1.1 ng/ml), thus offering a new classification marker. Also ex vivo, large amounts of sHLA-DR were released spontaneously by SF mononuclear cells and found to be related to the T-cell activation state. SF sHLA-DR may be shed in large complexes or micelles, as it eluted mainly at >450 kDa on gel filtration. Western blotting revealed that the majority of SF sHLA-DR consisted of full-length alpha- and beta-chains. Minor fractions of smaller sized antigens seemed to be generated by proteolytic cleavage rather than by alternative splicing, since only minute amounts of HLA-DRB mRNA lacking the transmembrane exon could be amplified by RT-PCR. Distinct forms of high-dose sHLA-DR, able to provoke rather than to suppress T-cell responses, are discussed as contributing to some HLA-DR disease association.

Adolescent↗
PubMed2000

Alteration of stimulus-specific guard cell calcium oscillations and stomatal closing in Arabidopsis det3 mutant.

Cytosolic calcium oscillations control signaling in animal cells, whereas in plants their importance remains largely unknown. In wild-type Arabidopsis guard cells abscisic acid, oxidative stress, cold, and external calcium elicited cytosolic calcium oscillations of differing amplitudes and frequencies and induced stomatal closure. In guard cells of the V-ATPase mutant det3, external calcium and oxidative stress elicited prolonged calcium increases, which did not oscillate, and stomatal closure was abolished. Conversely, cold and abscisic acid elicited calcium oscillations in det3, and stomatal closure occurred normally. Moreover, in det3 guard cells, experimentally imposing external calcium-induced oscillations rescued stomatal closure. These data provide genetic evidence that stimulus-specific calcium oscillations are necessary for stomatal closure.

Abscisic Acid↗
PubMed2000

Synthesis of spherical porous silicas in the micron and submicron size range: challenges and opportunities for miniaturized high-resolution chromatographic and electrokinetic separations.

Classical silica technology has reached its limit with respect to an ultimate minimum particle size of about 2 microm in diameter. Here, a novel process is presented which allows one to synthesize porous silica beads and control their particle diameter in situ, within the range of 0.2-2.0 microm. As a result, no sizing is required and losses of silica are avoided. Furthermore, the process enables one to control in situ the pore structural parameters and the surface chemistry of the silica beads. Even though surface funtionalized silicas made according to this process can principally be applied in fast HPLC the column pressure drop will be high even for short columns. In addition, the column efficiency, expressed in terms of the theoretical plate height is about H-2d(p) in the best case and limited by the A and C term of the Van Deemter equation. In other words the gain in total plate number when using 1-2 microm silica beads in short columns is minimal as compared to longer columns packed with 5 microm particles. Capillary electrochromatography (CEC) as a hybrid method enables the application of micron size as well as submicron size particles. This consequently enhances column efficiency by a factor of 5-10 when compared to HPLC. The use of short CEC columns packed with submicron size silicas provides the basis for fast and efficient miniaturized systems. The most significant feature of CEC as compared to HPLC is that the former allows one to resolve polar and ionic analytes in a single run. An alternative method for miniaturization is capillary electrophoresis (CE) which generates extremely high efficiencies combined with fast analysis. Its application, however, is limited to ionic substances.

Chromatography, Liquid↗
PubMed2000

Brassinosteroid signal transduction: still casting the actors.

Significant advances in the genetic dissection of brassinosteroid biosynthesis and signaling have been made during the past few years. Genetic and biochemical data have helped to elucidate the pathways of biosynthesis of brassinolide, the most active brassinosteroid. In addition, several models have been put forward for the perception of brassinolide by its putative receptor, BRI1, a ubiquitously expressed plasma membrane localized protein kinase. These studies provide the basic framework for future analysis of brassinosteroid signaling.

Brassinosteroids↗
PubMed2000

Experiencing transitions: an emerging middle-range theory.

Changes in health and illness of individuals create a process of transition, and clients in transition tend to be more vulnerable to risks that may in turn affect their health. Uncovering these risks may be enhanced by understanding the transition process. As a central concept of nursing, transition has been analyzed, its components identified, and a framework to articulate and to reflect the relationship between these components has been defined. In this article, the previous conceptual analysis of transitions is extended and refined by drawing on the results of five different research studies that have examined transitions using an integrative approach to theory development. The emerging middle-range theory of transitions consists of types and patterns of transitions, properties of transition experiences, facilitating and inhibiting conditions, process indicators, outcome indicators, and nursing therapeutics. The diversity, complexity, and multiple dimensionality of transition experiences need to be further explored and incorporated in future research and nursing practice related to transitions.

Adaptation, Psychological↗