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Regulation of sterol transport in human microvascular endothelial cells.

In cultured human dermal microvessel endothelial cells, the rate of efflux (about twofold greater than for fibroblasts under equivalent conditions) was coupled to an equivalent high rate of sterol net transport from the cells to the medium. This net transport was linked with esterification via lecithin:cholesterol acyltransferase. Since the use of free sterol by plasma transferase is constant, such increased net transport indicates that endothelial cells are highly efficient, in competition with plasma lipoproteins, in supplying free sterol for esterification. These results indicate the marked ability of endothelial cells to regulate and maintain their sterol balance in the face of high sterol levels to which these cells are uniquely exposed in human plasma.

Apolipoproteins↗

Role of the capsule in phagocytosis of Cryptococcus neoformans.

The capsule is closely associated with the virulence of Cryptococcus neoformans. The capsule inhibits phagocytosis by macrophages, monocytes, and neutrophils. Studies in our laboratory have shown that incubation of encapsulated cryptococci in normal human serum leads to deposition of large amounts of C3 fragments at the surface of the yeast and lesser amounts of IgG within the capsule. Thus, the capsule mediates two biologic activities with opposing effects. It is our current view that phagocytosis of the yeast is dependent on a balance between the antiphagocytic action of cryptococcal polysaccharide and the ability of the yeast to focus opsonically active complement fragments and the IgG at the capsular surface.

Animals↗

Workshop proceedings: managing conflict of interest in science. A little consensus and a lot of controversy.

There is no doubt that participants in the Conflict of Interest (COI) Workshop at the Society of Toxicology (SOT) 2005 Annual Meeting (New Orleans, 6-10 March 2005) engaged in a vigorous and useful exchange of diverse ideas and viewpoints. While there was consensus on the value and interest of this Workshop, there was less consensus and more controversy over many of the issues discussed during the Workshop, which included the distinction between bias and conflict, the success or failure of policies of disclosure, whether waivers should or should not be granted to conflicted individuals in order to seat a "balanced" committee with appropriate expertise, whether conflicted individuals retain the ability to recognize their own conflict, and more. The discussion left no doubt, however, that conflict of interest will remain an important and controversial issue in the scientific community for some time to come.

Bias↗

The management of immunosuppression: the art and the science.

The optimal use of immunosuppressant drugs requires an understanding of their mechanism of action as well as a basic understanding of the biology of transplant rejection and tolerance. The ability to tailor a drug regimen that strikes a fine balance between allograft maintenance and patient well-being demands a sensitivity to the patient's needs and expectations as well. The object of this article is to cover the basic biological principles involved in selecting an immunosuppressant protocol while sharing our experiences with these various regimen.

Anti-Inflammatory Agents↗

Foot position awareness in younger and older men: the influence of footwear sole properties.

OBJECTIVES: To test the hypotheses that foot position awareness is related positively to stability, positively to shoe sole hardness, and negatively to shoe sole thickness, and that foot position awareness declines with advancing years. SETTING: Older subjects were consecutive volunteers from a medical clinic; younger subjects were volunteers from the community. DESIGN: Randomized-order, cross-over, controlled comparison. PARTICIPANTS: Older subjects were a random sample of 13 healthy men, mean age 72.58 years, SD +/- 4.50. Younger subjects were a random sample of 13 male subjects from the general population, mean age 28.13 years, SD +/- 3.96. Additional selection criteria were absence of disabilities influencing ability to walk and no history of frequent falls. MEASUREMENTS: Balance failure frequency, defined as falls per 100 meters of beam walking; rearfoot angle in degrees, measured via an optical position measurement system; perceived maximum supination when walking, in degrees, estimated by subjects using a ratio scale; foot position error, in degrees, was defined as the rearfoot angle minus perceived maximum supination. RESULTS: Foot position error during walking: (1) increases with advancing years; footwear conditions absolute mean error for older sample of 15.48 degrees, SE +/- 1.56 degrees, and younger sample 5.44 degrees, SE +/- 1.03 degrees (P > .001); (2) is positively related to stability (r = .367, P < .001); (3) is positively related to midsole thickness (F(1,11) = 19.89, P < .001); (4) is negatively related to midsole hardness (F(2,22) = 29.80, P < .001); (5) correlates best with perceived maximum supination (r = .901, P < .001). CONCLUSION: Foot position awareness is related causally to stability; shoes with thin, hard soles provide better stability for men than those with thick, soft midsoles. Foot position awareness declines with advancing years.

Adult↗

Cationic liposomes enhance the rate of transduction by a recombinant retroviral vector in vitro and in vivo.

Cationic liposomes enhanced the rate of transduction of target cells with retroviral vectors. The greatest effect was seen with the formulation DC-Chol/DOPE, which gave a 20-fold increase in initial transduction rate. This allowed an efficiency of transduction after brief exposure of target cells to virus plus liposome that could be achieved only after extensive exposure to virus alone. Enhancement with DC-Chol/DOPE was optimal when stable virion-liposome complexes were preformed. The transduction rate for complexed virus, as for virus used alone or with the polycation Polybrene, showed first-order dependence on virus concentration. Cationic liposomes, but not Polybrene, were able to mediate envelope-independent transduction, but optimal efficiency required envelope-receptor interaction. When virus complexed with DC-Chol/DOPE was used to transduce human mesothelioma xenografts, transduction was enhanced four- to fivefold compared to that for virus alone. Since the efficacy of gene therapy is dependent on the number of cells modified, which is in turn dependent upon the balance between transduction and biological clearance of the vector, the ability of cationic liposomes to form stable complexes with retroviral vectors and enhance their rate of infection is likely to be important for in vivo application.

3T3 Cells↗

Does the Manchester triage system detect the critically ill?

BACKGROUND: The Manchester triage system (MTS) is now widely used in UK accident and emergency (A&E) departments. No clinical outcome studies have yet been published to validate the system. Safety of triage systems is related to the ability to detect the critically ill, which has to be balanced with resource implications of overtriage. OBJECTIVES: To determine whether the MTS can reliably detect those subsequently needing admission to critical care areas. METHODS: Analysis of emergency admissions to critical care areas and comparison with original A&E triage code by a nurse using the MTS at time of presentation. Retrospective coding of all cases according to the MTS by experts and case analysis to determine whether any non-urgent coding was due to the system or to incorrect coding. RESULTS: Sixty one (67%) of the patients admitted to a critical care area were given triage category 1 or 2 (that is, to be seen within 10 minutes of arrival). Eighteen cases given lower priority were due to incorrect coding by the triage nurse. Six cases were correctly coded by the MTS, of which five deteriorated after arrival in the A&E department. Only one case was critically ill on arrival and yet was coded as able to wait for up to one hour. CONCLUSIONS: The MTS is a sensitive tool for detecting those who subsequently need critical care and are ill on arrival in the A&E department. It did fail to detect some whom deteriorated after arrival in A&E. Most errors were due to training problems rather than the system of triage. Analysis of critically ill patients allows easy audit of sensitivity of the MTS but cannot be used to calculate specificity.

Critical Illness↗

Boehringer Mannheim award lecture 1995. La conference Boehringer Mannheim 1995. De novo design of alpha-helical proteins: basic research to medical applications.

The two-stranded alpha-helical coiled-coil is a universal dimerization domain used by nature in a diverse group of proteins. The simplicity of the coiled-coil structure makes it an ideal model system to use in understanding the fundamentals of protein folding and stability and in testing the principles of de novo design. The issues that must be addressed in the de novo design of coiled-coils for use in research and medical applications are (i) controlling parallel versus antiparallel orientation of the polypeptide chains, (ii) controlling the number of helical strands in the assembly (iii) maximizing stability of homodimers or heterodimers in the shortest possible chain length that may require the engineering of covalent constraints, and (iv) the ability to have selective heterodimerization without homodimerization, which requires a balancing of selectivity versus affinity of the dimerization strands. Examples of our initial inroads in using this de novo design motif in various applications include: heterodimer technology for the detection and purification of recombinant peptides and proteins; a universal dimerization domain for biosensors; a two-stage targeting and delivery system; and coiled-coils as templates for combinatorial helical libraries for basic research and drug discovery and as synthetic carrier molecules. The universality of this dimerization motif in nature suggests an endless number of possibilities for its use in de novo design, limited only by the creativity of peptide-protein engineers.

Amino Acid Sequence↗

Cardiac output and renal function during insulin hypertension in Sprague-Dawley rats.

Hyperinsulinemia has been reported to cause hypertension in rats; however, the renal and hemodynamic mechanisms are not known. In this study, changes in renal function, cardiac output (CO), and total peripheral resistance (TPR) were measured during chronic insulin infusion in eight rats (approximately 350 g). After a 4-day control period, a 7-day insulin infusion was begun (1.5 mU.kg-1.min-1 iv), together with glucose (22 mg.kg-1.min-1 iv) to prevent hypoglycemia. Mean arterial pressure (MAP), CO, TPR, and heart rate were measured 24 h/day. MAP increased from 92 +/- 1 to 100 +/- 2 mmHg on day 1 and was 108 +/- 4 mmHg by day 7 of insulin. CO tended to decrease during insulin infusion, although not significantly, averaging 94 +/- 4% of the control value of 121 +/- 7 ml/min. Heart rate did not change significantly from the control value of 384 +/- 8 beats/min. TPR increased significantly to 122 +/- 11% of control by day 7. In five rats, glomerular filtration rate and effective renal plasma flow decreased to 73 +/- 4 and 66 +/- 5% of control, respectively, during insulin. Urinary sodium excretion averaged 2.6 +/- 0.1 and 2.7 +/- 0.1 meq/day during the control and insulin-infusion periods, respectively. These results indicate that insulin hypertension in rats is initiated by an increase in TPR rather than by increased CO. Also, the fact that sodium balance was maintained at elevated arterial pressure suggests that the ability of the kidneys to excrete sodium was impaired chronically during insulin infusion.

Animals↗

Comparative analysis of the angiotensin-II receptor in placental vascular endothelial cells in preeclamptic and normotensive patients.

The aim of this study was to compare the immunoreactivity of angiotensin-II receptor type 1 (AT1R) in the vascular endothelial cells of human placental vessels in normal and preeclamptic pregnancies. Immunohistochemistry was used to examine the localization of AT1R in the vascular endothelium of human placental vessels. In preeclamptic patients without intrauterine growth retardation (IUGR) the mean histological index H score was significantly higher, but significantly decreased in patients with preeclampsia complicated by IUGR in comparison with the control group. Immunolocalization of AT1R in vascular endothelial cells in our study supports the view that angiotensin II may play a role in the regulation of vascular tone and vascular resistance and the actions of other vasoactive factors, vasodilators or vasoconstrictors. However, our results confirmed that AT1R immunoreactivity is elevated in vascular endothelial cells of human placenta from pregnancies complicated by preeclampsia, suggesting a higher activity of the renin-angiotensin-aldosterone system (RAAS) in women with preeclampsia. On the other hand reduced immunoreactivity of AT1R in placental vascular endothelial cells in pregnancy complicated by preeclampsia with IUGR may result from chronic higher RAAS activity and may suggest the decreased ability to compensate and the inability to restore the normal balance between vasodilators and vasoconstrictors. These results may also reflect destructive changes and dysfunction of the vascular endothelium in preeclamptic pregnancy with IUGR.

Aldosterone↗

Growth factors and pericellular components as a local signalling relay in the action of systemic hormones.

Recent years have shown that peptidic signals, originally identified as growth factors, may represent a local signalling system involved in the regulation of cell function under the dependence of systemic hormones. As an example, (i) adrenocortical cells are highly sensitive to transforming growth factor-beta (TGF beta) which is a powerful inhibitor of their differentiated functions; (ii) adrenocortical cells produce and secrete TGF beta, which is present in the adrenal cortex in situ; (iii) adrenocorticotropin (ACTH), which is the best known positive effector of adrenocortical functions induces an up-regulation of TGF beta receptors in adrenocortical cells. Altogether, these observations suggest that TGF beta may be a local signalling system acting in balance with the systemic hormone ACTH to eventually tune the ability of adrenocortical cells to produce corticosteroids.

Adrenal Cortex↗

A cetylated fatty acid topical cream with menthol reduces pain and improves functional performance in individuals with arthritis.

This investigation was an extension of a previous study conducted in our laboratory in which we showed that 1 month of treatment with a topical cream (Celadrin) consisting of cetylated fatty acids was effective for reducing pain and improving functional performance in individuals with osteoarthritis (OA) of the knee (Kraemer et al., Journal of Rheumatology, 2004). We wanted to verify that the addition of menthol to the compound would produce a similar percentage of improvement in therapeutic effects. We used a single treatment group with a pre-post experimental design to examine % treatment changes. Individuals diagnosed with OA of the knee (N = 10; age, 66.4 +/- 11.5 years) and severe pain (e.g., OA, rheumatoid arthritis) of the elbow (N = 8; age, 59.1 +/- 18.2 years) and wrist (N = 10; age, 60.3 +/- 16.8 years) were tested for pain and functional performance before and after 1 week of treatment with a topical cream consisting of cetylated fatty acids and menthol applied twice per day. In individuals with knee OA, significant improvements in stair-climbing ability (about 12%), "up-and-go" performance (about 12%), balance and strength (about 16.5%), and range of motion (about 3.5%) were observed, as were reductions in pain. In individuals with severe pain of the elbow and wrist, significant improvements in dynamic (about 22 and 24.5%, respectively) and isometric (about 33 and 42%, respectively) local muscular endurance were observed, as was a reduction in pain. Neither group demonstrated significant changes in maximal grip strength or maximal force production. One week of treatment with a topical cream consisting of cetylated fatty acids and menthol was similarly effective for reducing pain and improving functional performance in individuals with arthritis of the knee, elbow, and wrist. The % changes were consistent with our prior work on the compound without menthol. Further work is needed to determine the impact of menthol in such a cream. Nevertheless, our data support the use of a topical cream consisting of cetylated fatty acids (with or without menthol) for enhancing the potential for exercise training in this population.

Activities of Daily Living↗

The effect of postruminal amino acid flow on muscle cell proliferation and protein turnover.

An experiment was conducted to characterize the effects of postruminal administration of casein, glutamine, cornstarch, and water on protein turnover and in vitro muscle cell proliferation. Four MARC III steers (205 kg) were fed a protein-restricted bromegrass hay-based diet (2.86 Mcal of DE/kg and 13.6 g of N/kg). Using a 4 x 5 Latin square arrangement balanced for residual effects, casein and glutamine, equal to 50% of basal dietary nitrogen intake, cornstarch, isocaloric with casein infusion, or an equal volume of water was continuously infused into the abomasum of steers. Blood samples, collected every 2 h for 24 h after 7 d of infusion, were tested for the effect on cell cycle kinetics and myotube protein turnover. Urine and feces were also collected for 4 d after blood sampling for nitrogen balance and fractional skeletal muscle degradation. The mitogenic activity and ability of serum to influence rate of myoblast proliferation in a dose-dependent manner was influenced (P < .05) by infusate: casein > cornstarch > glutamine = water. Abomasal infusion of casein and cornstarch increased (P < .05) in vitro muscle protein synthesis and decreased (P < .05) in vitro muscle protein degradation, whereas abomasal glutamine infusion only increased (P < .05) in vitro muscle protein synthesis. Abomasal glutamine infusion decreased (P < .05) fractional skeletal muscle protein degradation and synthesis; however, fractional muscle protein accretion tended to increase due to a greater decline in fractional muscle protein degradation. In contrast, abomasal casein infusion increased (P < .05) fractional skeletal muscle protein synthesis, breakdown, and accretion. These results suggest that muscle hypertrophy may be regulated by serum constituents whose activity is affected by postruminal amino acid flow.

Amino Acids↗

Effect of carboxyl group in O-methacryloyl-N-acyl tyrosines on adhesiveness to unetched human dentin.

We have reported that the carboxylic group plays an important role in the adhesion of methacryloyl amino acid--2-hydroxyethyl methacrylate type restorative resin to dentin surfaces. However, our study so far has been limited to the methacryloyl amino acid that has only one carboxylic acid. In this investigation, three new O-methacryloyl-N-acyl tyrosines (MAATY) that have one or two carboxylic groups in the acyl group, and thus two or three carboxylic groups in MAATY, were prepared and evaluated for their bond strength to unetched dentine. Higher bond strength was observed when the MAATY contained larger number of carboxylic acid groups. Factor analysis of the bonding strength revealed that the hydrogen bond ability of the carboxylic acid and the hydrophile-lipophile balance (HLB) affected the bond strength.

Adhesiveness↗

Role of IL-12 in the induction and potentiation of IFN-gamma in response to bacillus Calmette-Guérin.

Although Mycobacterium bovis bacillus Calmette-Guérin (BCG) has been accepted as the most effective agent in clinical use against superficial bladder cancer, its mechanism of action remains incompletely understood. A kinetic analysis in assessing the potential role of cytokines from BCG-stimulated murine splenocytes showed that IL-12 expression preceded that of other cytokines. Experiments subtracting endogenous BCG-driven IL-12 using neutralizing Ab or augmenting its activity with supplemental rIL-12 revealed not only that IL-12 plays a dominant role in IFN-gamma induction but also that it is normally dose limiting. A striking increase in IFN-gamma production could be generated in both mouse and human immunocompetent cell culture by the addition of even a small amount of rIL-12. Moreover, this same synergistic effect could be replicated during in vivo administration of BCG plus rIL-12 into the mouse bladder and was observed in a patient receiving intravesical combination therapy. In costimulation cultures, this synergy appeared to partially rely on IL-18 and IL-2 and could be down-regulated by IL-10. This suggests that a dynamic interplay between Th1 and Th2 cytokines is responsible for net IFN-gamma production. The ability of supplemental exogenous IL-12 to strongly shift this balance toward Th1 provides an immunological basis for using it in conjunction with intravesical BCG for bladder cancer immunotherapy.

Adjuvants, Immunologic↗

Sex brings transposons and genomes into conflict.

Given that transposons are so abundant in mammalian genomes, it is natural to assume that through their maintenance the host gains some net benefit. This need not be true; sexual reproduction allows a transposon to go to fixation if the reduction in fitness of the host is anything less than two-fold. Obligate outcrossing sexual reproduction therefore favors the evolution of aggressive transposons, which in turn select for the evolution of host mechanisms that suppress transposon activity. Hosts that have asexual or self-fertilizing generations will select for transposons that are more benign and self-limiting than those of obligate sexuals, and obligate asexuals and uniparental organelle genomes will be free of active transposons if these impose any fitness penalty. We are interested in host mechanisms that suppress transposons in sexuals and have found that mammals (all of which are obligate sexuals) control their large populations of potentially active retroposons by methylating the five position of cytosine residues within promoter elements. This causes strong transcriptional repression and assembly of the affected sequences into the condensed state. Methylation also causes permanent inactivation in the germline by driving C-->T transition mutations at methylated sites. It is now known that methylation remains in place for the large majority of the life of germ cells and is essential for control of the very large transposon burden. There is pressure on transposons to evolve mechanisms that overcome host suppression, and over evolutionary time, the balance swings back and forth between parasite and host. The ability of the mammalian genome to absorb and accumulate additional transposons has caused the amount of reverse transcriptase coding sequence in the human genome to far exceed the sum total of all cellular coding sequence. While transposons could, in principle, contribute functions useful to the host, the fact that asexual species and uniparental organelle genomes lack transposons is strong evidence that transposons have a net deleterious effect even in genomes that might be thought to require an additional source of plasticity. The abundance of transposons in many genomes cannot be taken as evidence of a mutualistic relationship, and the conflict between transposons and genomes may have actually retarded rather than accelerated evolution. It is suggested that the relationship between sex and transposons is as follows: (i) Obligate sexuals will tend to harbor aggressive transposons limited largely by host suppressive mechanisms, which in mammals involve methylation of transposon promoters. (ii) The aggressiveness of transposons in facultative sexuals and self-fertilizing sexuals will be in part self-limited and will be proportional to the relative frequency of asexual and outcrossing sexual generations. (iii) Obligate asexuals arid organelles transmitted in a uniparental manner will have no active transposons if these have a net negative effect on host fitness.

Animals↗

[Effect of different fertilization system on soil nutrient budget].

A long-term experiment was carried out on a damp palm soil about ten years under the condition of nutrient recycling and reutilization. The quantity of crop nutrients transferred from the system, and the nutrient budget of N, P and K in soil were studied. The results of a ten-year field experiment indicated that the use of nutrients recycled in the farming systems with appropriate amount of fertilizers applied according to the soil nutrient supplying ability could not only produce high crop yield, but also balance the soil nutrient budget, so that, there were no significant surplus of nutrients (mainly inorganic nitrogen) which might emit or leach out of soil into environment.

Agriculture↗