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At least 397 records · Page 22Linked to original sources
PubMed2004

The decrease in plasma ghrelin concentrations following bariatric surgery depends on the functional integrity of the fundus.

BACKGROUND: Gastric bypass surgery, which involves the production of a reduced stomach pouch,has been shown to markedly suppress circulating ghrelin concentrations. Since bypassing the ghrelin-producing cell population may be relevant to the disruption of fundic-derived factors participating in food intake signaling, the effect of weight loss induced by either adjustable gastric banding (AGB), Roux-en-Y gastric bypass (RYGBP) or biliopancreatic diversion (BPD) was studied. METHODS: 16 matched obese patients [35.0 + 2.4 years; initial body weight 124.8 +/- 5.7 kg; body mass index (BMI) 47.1 +/- 2.2 kg/m(2)] in whom similar weight loss had been achieved by either AGB (n=7), RYGBP (n=6) or BPD (n=3) were studied. Blood was obtained for biochemical and hormonal analyses. Body composition was assessed by air-displacement-plethysmography. RESULTS: Comparable weight loss (AGB: 26.1 +/- 5.1 kg; RYGBP: 32.1 +/- 5.0; BPD: 31.7 +/- 6.1; P=NS) and decrease in percentage body fat (AGB: 10.0 +/- 1.5%; RYGBP: 14.2 +/- 2.8; BPD: 10.3 +/- 1.0; P=NS) induced by bariatric surgery exerted significantly different (P=0.004) effects on plasma ghrelin concentrations, depending on the surgical procedure applied (AGB: 480 +/- 78 pg/ml; RYGBP: 117 +/- 34; BPD: 406 +/- 86). Without significant differences in BMI, body fat, glucose, triglycerides, cholesterol, insulin and leptin levels, patients who had undergone the RYGBP exhibited statistically significant diminished circulating fasting plasma ghrelin concentrations compared with the other two bariatric techniques which conserve direct contact of the fundus with ingested food (P=0.003 vs AGB and P=0.020 vs BPD). CONCLUSION: Fasting circulating ghrelin concentrations in patients undergoing diverse bariatric operations depend on the degree of dysfunctionality of the fundus.

Adult↗
PubMedDate not supplied

Studies on the nature of the primary reactions of photosystem II in photosynthesis. II. The modification of the functional integrity of the photochemical active centers of system II by a alpha-bromo-benzyl-malodinitril and accompyaning effects on chloroplasts.

The effect of alpha-bromo-alpha-benzylmalodinitril (BBMD) on the oxygen evolution and on the absorption changes at 515 nm and 704 nm has been investigated in spinach chloroplasts. It has been found: 1. Under repetitive flash excitation conditions, where the back reaction around system II is practically excluded for kinetical reasons, BBMD does not resotre the 515 nm absorption change in DCMU poisoned chloroplasts. 2. Under single flash excitation conditions, where the back reaction around system II becomes prominent in the presence of DCMU, BBMD moderately inhibits this back reaction. The deleterious effect is pronounced by preillumination with short flashes during the BBMD incubation period of the chloroplasts in the absence of DCMU. 3. Incubation of the chloroplasts with BBMD leads to an activity loss of oxygen evolution which increases with the time td between the repetitive short excitation flashes and with the dark incubation time. Preillumination during the incubation period with tbbmd significantly enhances the effect. 4. In the absence of artificial electron acceptors BBMD suppresses in DCMU poisoned chloroplasts the 704 nm absorption change reflecting an internal cyclic electron flow around system I. On the other hand the linear electron transport at system I mediated by DCIP plus ascorbate as electron donor couple and benzylviologen as electron acceptor is not distrubed by BBMD. 5. BBMD incubation of chloroplasts accelerates the decay rate of the field indicating 515 nm absorption change. Based on these experimental findings the conclusion has been drawn, that -- in contrast to the assumption of Brandon and Elgersma (Biochim. Biophys. Acta 292, 753--762 [1973]) -- BBMD does not accept electrons from the primary electron acceptor X 320 of system II in DCMU poisoned chloroplasts. BBMD rather acts as a system I electron acceptor. Furthermore, BBMD exerts deleterious effects on the center of photosystem II, accompanied by a weak ADRY-effect on the water-splitting enzyme system Y. As a tentative explanation of the BBMD-action on system II it is assumed that BBMD transforms the photochemical centers of system II into dissipative energy sinks.

Benzyl Compounds↗
PubMed1985

Functional integrity of anterior pituitary cells separated by a density gradient.

Using a continuous Percoll density gradient, endocrine cells of the anterior pituitary were separated. The cells were obtained from adult female Sprague-Dawley rats which had been ovariectomized for 7 days. The gradient revealed two equally sized populations of cells with densities of about 1.02 and 1.09 g/ml. Ninety-two per cent of the cellular GH content, 64% of LH, and 60% of TSH were found in the high density peak. Sixty-one per cent of the cellular Prl appeared in the low density peak. Immunocytochemical staining of the LH containing cells showed that 74% of the gonadotrophs were in the high density peak. After separation, the cells retained their responsiveness to LRH, TRH and GRF. Culture conditions influenced stimulated hormone release. Before stimulation, the cells were cultured either in tissue culture flasks (attached cells) or in Petri dishes (cells in suspension) for 3 days. After TRH-stimulation, suspended thyrotrophs released more TSH than attached thyrotrophs. Comparing the cells of both peaks, attached thyrotrophs of the high density peak showed higher stimulated TSH-release than those of the low density peak. The response of the gonadotrophs and somatotrophs to stimulation did not differ when culture conditions were changed. The present results demonstrate that the secretory activity of endocrine cells is influenced by culture conditions and should be evaluated fore each cell type.

Animals↗
PubMed1991

Growth of mouse endometrial luminal epithelial cells in vitro: functional integrity of the oestrogen receptor system and failure of oestrogen to induce proliferation.

Normal endometrial luminal epithelial cells isolated from ovariectomized approximately 40-day-old BALB/cCrgl mice were purified by Percoll density gradient centrifugation and grown as primary cultures in collagen gel matrix and serum-free medium. Cells increased threefold in number during the 9-day culture period. Deletion of insulin, epidermal growth factor or bovine serum albumin resulted in decreased growth. Addition of any single factor to the unsupplemented medium had no effect. Relatively high levels of cytosolic oestrogen receptors and progestin receptors were demonstrable in the cultures. Addition of oestrogen did not enhance epithelial cell proliferation. On the contrary, all doses of oestrogen (180 fmol/l to 218 nmol/l) were inhibitory. Continuous exposure to oestradiol-17 beta (1.8 nmol/l) for 9 days in serum-free medium resulted in a decrease in cytosolic oestrogen receptors with an associated nuclear accumulation of oestrogen receptors. A corresponding increase in cytosolic progestin receptors was also observed, indicating that no qualitative modification of the oestrogen receptor system had occurred. Thus, as previously reported for vaginal epithelial cells, oestrogen, despite its stimulation of specific product synthesis (progestin receptors), did not increase proliferation of endometrial luminal epithelial cells in this culture system.

Animals↗
PubMed1993

Functional integrity of proximal tubule cells: effects of temperature and preservation solutions.

Electrophysiologic and morphologic changes during cooling and perfusion with preservation solutions in isolated perfused proximal straight tubules from Swiss white mice were investigated. In standard Ringer-substrate solution, cooling from 37 degrees C to 22 and 4 degrees C depolarized both transepithelial potential and basolateral cell membrane potential. Basolateral k+ transference number and cell membrane conductances were also significantly reduced. An increase in intracellular Na+ activity was observed only during cooling from 37 to 4 degrees C. No cell swelling was detected when tubules were perfused with Ringer-substrate solution at all three temperatures up to 1 h. Perfusion with Euro-Collins' (EC) solution at 37 degrees C resulted in rapid cell swelling, associated with rapid deterioration of transepithelial potential. Substitution of glucose with mannitol abolished the damaging effect of EC solution at 37 degrees C. EC perfusion at 22 degrees C also led to cell swelling and deterioration of transepithelial potential, but after a 10-min delay. In comparison, perfusion with University of Wisconsin (UW) solution at 22 or 37 degrees C had no effect on cell volume. Less damage to transepithelial potential was observed after the UW perfusion. It was concluded that EC solution is more damaging than UW solution to kidney tubules at 22 and 37 degrees C. The presence of EC solution in the renal interstitium during the rewarming phase may contribute significantly to reperfusion injuries in kidney transplantation.

Adenosine↗
PubMed1992

Functional integrity of proximal tubule cells. Effects of hypoxia and ischemia.

Effects of warm hypoxia and ischemia on electrophysiologic properties of isolated perfused mouse proximal straight tubules were studied. Oxyrase (5 to 10 microliters/mL) was added to the hypoxic and ischemic solutions to lower the oxygen tension to 5 mm Hg. The ischemic solution also simulated acidosis, K+ and lactate accumulation, and substrate deprivation. Twenty-minute tubular perfusion with the hypoxic and ischemic solutions (lumen and bath) at 37 degrees C did not significantly alter basolateral membrane potential, basolateral K+ transference number, or intracellular Na+ activity from control values of -69 +/- 1 mV (N = 91), 0.71 +/- 0.01 (N = 15), and 15.2 +/- 0.8 mM (N = 12), respectively. However, the hypoxic and ischemic perfusions decreased transepithelial potential by 40% (hypoxia: -1.7 +/- 0.1 to -1.1 +/- 0.1 mV [N = 30; P < 0.001]; ischemia: -1.4 +/- 0.1 to -0.82 +/- 0.05 mV [N = 17; P < 0.001]). A similar extent of reduction in transepithelial resistance was observed (hypoxia: 14.3 +/- 1.0 to 9.2 +/- 1.1 omega.cm2 [N = 7; P < 0.005]; ischemia: 12.6 +/- 1.2 to 8.1 +/- 1.0 omega.cm2 [N = 6; P < 0.03]). In addition, neither apical (R(ap)) nor basolateral (Rbl) cell membrane resistances were significantly altered after the ischemic perfusion (control: R(ap) = 369 +/- 48 omega.cm2; Rbl = 92 +/- 11 omega.cm2 [N = 63]; reperfusion: R(ap) = 454 +/- 88 omega.cm2; Rbl = 101 +/- 16 omega.cm2 [N = 21]). It was concluded that tubular cells are able to maintain their electrogenic ionic transport after short-term exposure to hypoxic or ischemic conditions. However, cell-to-cell junctions are damaged by these insults, which could possibly increase leakage and decrease the efficiency of the active transport.

Animals↗
PubMed2006

Integrative functional assays, chemical genomics and high throughput screening: harnessing signal transduction pathways to a common HTS readout.

Chemical genomics is a drug discovery strategy that relies heavily on high-throughput screening (HTS) and therefore benefits from functional assay platforms that allow HTS against all relevant genomic targets. Receptor Selection and Amplification Technology (R-SAT) is a cell-based, high-throughput functional assay where the receptor stimulus is translated into a measurable cellular response through an extensive signaling cascade occurring over several days. The large biological and chronological separation of stimulus from response provides numerous opportunities for enabling assays and increasing assay sensitivity. Here we review strategies for building homogeneous assay platforms across large gene families by redirecting and/or amplifying signal transduction pathways.

Animals↗
PubMed2000

Non-invasive evaluation of the location, the functional integrity and the oxygen supply of implants: 19F nuclear magnetic resonance imaging of perfluorocarbon-loaded Ba2+-alginate beads.

19F nuclear magnetic resonance imaging (MRI) can be used as a non-invasive tool to simultaneously determine the location, the integrity and the oxygen supply of Ba2+-alginate implants. This requires that the beads (implants) are pre-loaded with the perfluorocarbon compound F-44E. Implantation of solid 19F-labelled beads into the peritoneum, below the kidney capsule or into the muscle of Wistar WU rats demonstrated that these beads could be detected by 19F-MRI for up to 18 months after implantation. This indicated that F-44E is not considerably released from the beads during implantation. The signal to noise ratio of liquid-core beads was higher by a factor of 4 than the signal to noise ratio of solid beads, but liquid-core beads were more fragile and also too large for implantation under the kidney capsule and into the intramuscular tissue. Quantitative 2-dimensional 19F-T1 maps (resolution 0.5 x 0.5 mm) could be deduced from 19F-MRI measurements. These T1-maps correlated to the local pO2-values. The partial oxygen pressure estimated in F-44E-loaded Ba2+-alginate beads showed that the oxygen supply inside the beads was very poor when they were implanted below the kidney capsule or into the peritoneal cavity. These low pO2-values obtained for the renal subcapsular site and the peritoneum may explain the failure of previous immunoisolated islet transplantation studies using these locations.

Alginates↗
PubMed2006

Molecular basis of TCR selectivity, cross-reactivity, and allelic discrimination by a bacterial superantigen: integrative functional and energetic mapping of the SpeC-Vbeta2.1 molecular interface.

Superantigens activate large fractions of T cells through unconventional interactions with both TCR beta-chain V domains (Vbetas) and MHC class II molecules. The bacterial superantigen streptococcal pyrogenic exotoxin C (SpeC) primarily stimulates human Vbeta2(+) T cells. Herein, we have analyzed the SpeC-Vbeta2.1 interaction by mutating all SpeC residues that make contact with Vbeta2.1 and have determined the energetic and functional consequences of these mutations. Our comprehensive approach, including mutagenesis, functional readouts from both bulk T cell populations, and an engineered Vbeta2.1(+) Jurkat T cell, as well as surface plasmon resonance binding analysis, has defined the SpeC "functional epitope" for TCR engagement. Although only two SpeC residues (Tyr(15) and Arg(181)) are critical for activation of virtually all human CD3(+) T cells, a larger cluster of four hot spot residues are required for interaction with Vbeta2.1. Three of these residues (Tyr(15), Phe(75), and Arg(181)) concentrate their binding energy on the CDR2 loop residue Ser(52a), a noncanonical residue insertion found only in Vbeta2 and Vbeta4 chains. Plasticity of this loop is important for recognition by SpeC. Although SpeC interacts with the Vbeta2.1 hypervariable CDR3 loop, our data indicate these contacts have little to no influence on the functional interaction with Vbeta2.1. These studies also provide a molecular basis for selectivity and cross-reactivity of SpeC-TCR recognition and reveal a degree of fine specificity in these interactions, whereby certain SpeC mutants are capable of distinguishing between different alleles of the same Vbeta domain subfamily.

Alleles↗
PubMed1990

Techniques for integrating functions of hospital administration and medical staff.

To be successful in today's competitive market, hospital/medical staff relations must evolve to the point where the two entities work together within the health care institution in a combined effort to help people achieve their life goals by minimizing the effects of illness and maximizing physical and mental health. This article sets forth simple, practical techniques for moving a health care institution toward this goal.

Hospital Administration↗
PubMed1999

The functional integrity and fate of cryopreserved ram spermatozoa in the female tract.

Cryopreservation advances capacitation-like changes in ram spermatozoa. These changes are reflected in an increased fertilizing ability compared with fresh spermatozoa, followed by an accelerated decline in fertilizing ability after incubation in vitro or in vivo. Furthermore, frozen-thawed spermatozoa are released earlier than fresh spermatozoa after binding to oviduct cells in vitro, confirming their physiological readiness to participate in fertilization despite their short lifespan. After insemination large numbers of spermatozoa are lost from the female reproductive tract of the ewe via the vagina. Frozen-thawed spermatozoa are expelled faster than fresh spermatozoa. The advanced membrane status of frozen-thawed spermatozoa may provoke their rapid loss and possibly makes them more vulnerable to attack by uterine leucocytes, or by some other mechanism, as a high proportion of spermatozoa lost from the tract are decapitated. The observed destabilization of the membranes of cryopreserved spermatozoa is accompanied by impaired sperm transport, associated with mitochondrial injury, necessitating intrauterine deposition of frozen-thawed semen to obtain satisfactory fertility after artificial insemination. However, the frozen-thawed spermatozoa that can participate in fertilization may contribute to increased embryonic loss by the advancement of cleavage or through a direct effect of cryopreservation on the male genome.

Animals↗