Remote monitoring of vibrational information in spider webs.

Spiders are fascinating model species to study information-acquisition strategies, with the web acting as an extension of the animal's body. Here, we compare the strategies of two orb-weaving spiders that acquire information through vibrations transmitted and filtered in the web. Whereas Araneus diadematus monitors web vibration directly on the web, Zygiella x-notata uses a signal thread to remotely monitor web vibration from a retreat, which gives added protection. We assess the implications of these two information-acquisition strategies on the quality of vibration information transfer, using laser Doppler vibrometry to measure vibrations of real webs and finite element analysis in computer models of webs. We observed that the signal thread imposed no biologically relevant time penalty for vibration propagation. However, loss of energy (attenuation) was a cost associated with remote monitoring via a signal thread. The findings have implications for the biological use of vibrations by spiders, including the mechanisms to locate and discriminate between vibration sources. We show that orb-weaver spiders are fascinating examples of organisms that modify their physical environment to shape their information-acquisition strategy.

Herpes zoster infection, vaccination and immunocompromised rheumatology patients.

Varicella is a self-limiting and relatively mild disease of childhood, although it is frequently more severe and complicated among the immunocompromised rheumatology patients on immunomodulator therapies. In addition, future reactivation of the dormant virus in dorsal root ganglia may cause herpes zoster infection, which can be very debilitating. In this manuscript, we discuss the nature of this infection along with its potential vaccine especially among rheumatology patients.

The impact of HSV for inflammatory arthropathy patients.

Herpes simplex virus type 1 (HSV-1), also known as herpes labialis, is the etiologic agent of vesicular lesions of the oral mucosa commonly referred to as "cold sores". HSV-1 can also cause clinical disease in a wide variety of other anatomic locations including the genitalia, liver, lung, eye, and central nervous system. These infections can be severe, particularly in the setting of immunosuppression, such as inflammatory arthropathy patients on Methotrexate ± biological therapies. Here, we highlight the importance of physician awareness of HSV due to its potential impact for rheumatology patients.

Osteonecrosis following alcohol, cocaine, and steroid use.

Alcohol, steroids and cocaine have all been shown to be independent risk factors for osteonecrosis when taken in excess. Here we present a case of a young girl who developed debilitating osteonecrosis secondary to low doses of alcohol, steroids and cocaine. We feel it is important to highlight to those caring for such patients of the potential devastating complication of these three agents.

Adherence to anti-retroviral therapy among HIV patients in Bangalore, India.

INTRODUCTION: Human Immunodeficiency Virus (HIV) has an estimated prevalence of 0.9% in India (5.2 million). Anti-retroviral drugs (ARV) are the treatments of choice and non-adherence is an important factor in treatment failure and development of resistance, as well as being a powerful predictor of survival. This study assesses adherence to ARV in HIV positive patients in Bangalore, India, a country where only 10% of those who need therapy are receiving it. METHODS: A cross-sectional anonymous questionnaire survey of 60 HIV antibody positive patients was carried out with patients attending HIV outpatient services at two centres: The Chest and Maternity Centre, Rajajinagar, and Wockhardt Hospital and Heart Institute, Bangalore. Consent was obtained. Translation was done by a translator and doctors where required. Data was analysed using SPSS statistical analysis. RESULTS: A response rate of 88% (53/60) was achieved. The mean patient age was 39.98 years, with 50% aged 30-40, and 73.6% of participants being male. Mean family size was 4.8 (1-13). 21% lived less than 50 kms and 21% greater than 400 kms from clinic.60% reported they were fully adherent. Adherence was statistically significantly linked to regular follow-up attendance (70.5%, p = 0.002). No other results were statistically significant but trends were found. "100% adherence" trends were seen in older patients, male gender, those from larger families, those who had a previous AIDS defining illness, those taking fewer tablets, and without food restrictions. Commonest side-effects causing non-adherence were metabolic reasons (66%) and GI symptoms (50%). No trends were seen for education level, family income, distance travelled to clinic, time since diagnosis, or time on ART. CONCLUSION: Regular attendance for follow up was statistically significant for 100% lifetime adherence. Positive trends were seen in those in larger families, older, those who had AIDS defining illness, simple regimes, and without side-effects. Education, income, distance travelled and length of time diagnosed or treated had no effect on adherence.

A Spider's Vibration Landscape: Adaptations to Promote Vibrational Information Transfer in Orb Webs.

Spider orb webs are used not only for catching prey, but also for transmitting vibrational information to the spider. Vibrational information propagates from biological sources, such as potential prey or mates, but also abiotic sources, such as wind. Like other animals, the spider must cope with physical constraints acting on the propagation of vibrational information along surfaces and through materials-including loss of energy, distortion, and filtering. The spider mitigates these physical constraints by making its orb web from up to five different types of silks, closely controlling silk use and properties during web building. In particular, control of web geometry, silk tension, and silk stiffness allows spiders to adjust how vibrations spread throughout the web, as well as their amplitude and speed of propagation, which directly influences energy loss, distortion, and filtering. Turning to how spiders use this information, spiders use lyriform organs distributed across their eight legs as vibration sensors. Spiders can adjust coupling to the silk fibers and use posture to modify vibrational information as it moves from the web to the sensors. Spiders do not sense all vibrations equally-they are least sensitive to low frequencies (<30 Hz) and most sensitive to high frequencies (ca. 1 kHz). This sensitivity pattern cannot be explained purely by the frequency range of biological inputs. The role of physical and evolutionary constraints is discussed to explain spider vibration sensitivity and a role of vibration sensors to detect objects on the web as a form of echolocation is also discussed.

Decoding the locational information in the orb web vibrations of Araneus diadematus and Zygiella x-notata.

A spider's web is a multifunctional structure that captures prey and provides an information platform that transmits vibrational information. Many physical factors interact to influence web vibration and information content, from vibration source properties and input location, to web physical properties and geometry. The aim of the study was to test whether orb web vibration contains information about the location of the source of vibration. We used finite-element analysis model webs to control and vary major physical factors, investigating webs where spiders use a direct or remote monitoring strategy. When monitoring with eight sensors (legs) at the web centre, a comparison of longitudinal and transverse wave amplitude between the sensors gave sufficient information to determine source direction and distance, respectively. These localization cues were robust to changes in source amplitude, input angle and location, with increased accuracy at lower source amplitudes. When remotely monitoring the web using a single thread connected to the web's hub (a signal thread), we found that locational information was not available when the angle of the source input was unknown. Furthermore, a free sector and a stiff hub were physical mechanisms to aid information transfer, which provides insights for bioinspired fibre networks for sensing technologies.

Successful treatment of Takayasu arteritis with rituximab as a first-line immunosuppressant.

Takayasu arteritis is a rare large vessel vasculitis which has traditionally been treated with high-dose steroids. There have been a small number of publications where biological agents have been used to manage refractory cases. To the authors knowledge, there are no publications using biological agents in combination with steroids as a first-line treatment in Takayasu arteritis. In this publication, we document the case of Takayasu arteritis, in a 39-year-old woman, where rituximab was used in combination with steroids as a first-line agent in the setting of poorly controlled bipolar affective disorder.

Tuning the instrument: sonic properties in the spider's web.

Spider orb webs are multifunctional, acting to absorb prey impact energy and transmit vibratory information to the spider. This paper explores the links between silk material properties, propagation of vibrations within webs and the ability of the spider to control and balance web function. Combining experimental and modelling approaches, we contrast transverse and longitudinal wave propagation in the web. It emerged that both transverse and longitudinal wave amplitude in the web can be adjusted through changes in web tension and dragline silk stiffness, i.e. properties that can be controlled by the spider. In particular, we propose that dragline silk supercontraction may have evolved as a control mechanism for these multifunctional fibres. The various degrees of active influence on web engineering reveals the extraordinary ability of spiders to shape the physical properties of their self-made materials and architectures to affect biological functionality, balancing trade-offs between structural and sensory functions.

Effects of phospholipid composition on the metabolism of triacylglycerol, cholesteryl ester and phosphatidylcholine from lipid emulsions injected intravenously in rats.

Lipid emulsions were prepared with a similar size and lipid composition to natural lymph chylomicrons, but in which the surface phospholipid was either egg phosphatidylcholine, dioleoyl-, dimyristoyl-, dipalmitoyl- or 1-palmitoyl-2-oleoylphosphatidylcholine (EYPC, DOPC, DMPC, DPPC or POPC). When injected into the bloodstream of conscious rats, the emulsions containing EYPC or POPC were metabolized similarly to natural chylomicrons, consistent with rapid lipoprotein lipase-mediated hydrolysis of triacylglycerols, followed by hepatic uptake of the remnants derived from the emulsions. Phospholipids from the injected emulsions were removed more slowly and became associated with the high-density lipoprotein fractions of the plasma. Emulsions containing DPPC were metabolized differently. Triacylglycerols disappeared very slowly from plasma, indicating lack of hydrolysis by lipoprotein lipase, and phospholipid radioactivity did not transfer to high-density lipoprotein. With emulsions containing DMPC, the plasma removal rates for emulsion triacylglycerols and cholesteryl esters were fast, but phospholipid radioactivity failed to transfer to the high-density lipoprotein fractions of plasma. With DOPC emulsions, clearances were slower than EYPC or POPC emulsions, but transfer to high-density lipoproteins was efficient. Therefore, an unsaturated chain at the glycerol 2-position was necessary for rapid hydrolysis by lipoprotein lipase and for efficient transfer of phospholipids to high-density lipoproteins. With an unsaturated chain at the glycerol 2-position, a saturated chain at the glycerol 1-position optimized the rate of remnant removal from the plasma.

Effects of sphingomyelin and phosphatidylcholine acyl chains on the clearance of triacylglycerol-rich lipoproteins from plasma. Studies with lipid emulsions in rats.

Series of lipid emulsions were prepared as physical models of lymph chylomicrons. The emulsion phospholipid was systematically varied with respect to sphingomyelin, in 0-100% mixtures with egg yolk phosphatidylcholine (EYPC). In other emulsions, the phospholipid was systematically varied with respect to dipalmitoylphosphatidylcholine (DPPC) in 0-100% mixtures with 1-palmitoyl-2-oleoylphosphatidylcholine (POPC). All emulsions contained unlabeled free cholesterol, radiolabeled triolein (TO) and radiolabeled cholesteryl oleate (CO). The emulsions were injected into conscious rats to measure the clearances of emulsion TO and CO and the capture of lipid radioactivity by selected organs. The emulsions containing EYPC or POPC were metabolized similarly to lymph chylomicrons, consistent with rapid lipoprotein lipase-mediated hydrolysis of emulsion TO followed by hepatic uptake of the CO in the triglyceride-depleted emulsion remnants. Emulsions stabilized with either 1-oleoyl-2-stearoyl- or 1-stearoyl-2-oleoylphosphatidylcholine (OSPC or SOPC) were metabolized similarly. Increasing amounts of sphingomyelin in EYPC emulsions progressively slowed the removal of TO and CO labels from plasma. With 50% sphingomyelin clearance was very slow, while emulsion clearance was negligible with 100% sphingomyelin. Emulsions containing 20% of DPPC in POPC were metabolized similarly to 100% POPC, but 40% or more of DPPC progressively slowed the removal from plasma of both TO and CO. With 100% DPPC clearance was characterized by a rapid initial removal of about 30% of the injected material, followed by a second phase when removal was negligible, suggesting lack of hydrolysis of triacylglycerols by lipoprotein lipase. Changes in the apolipoproteins associated with the emulsions probably mediated the observed changes in clearance.

Effects of triacylglycerol-saturated acyl chains on the clearance of chylomicron-like emulsions from the plasma of the rat.

We previously found that a single saturated acyl chain at the glycerol 2-position affected the metabolism of chylomicrons. The explanation for the effect is not clear, but could be reproduced by saturated monoacylglycerols. In the present work we have extended our measurements to several different triacylglycerols containing one or two saturated chains in specific locations in an attempt to define structural features that affect chylomicron clearance. Lipid emulsions containing triacylglycerol, egg yolk phosphatidylcholine, free cholesterol, cholesteryl oleate (CO) and labelled with 3H-CO and [14C]triolein (OOO) were prepared as models of lymph chylomicrons. When injected intravenously into rats, the metabolism of the emulsions was influenced by the acyl chains of the constituent triacylglycerols. Compared with emulsions containing OOO as the only triacylglycerol, plasma clearances of emulsion [3H]CO were extremely slow in emulsions containing either 1,2-dioleoyl-3-stearoylglycerol (OOS) or 1-stearoyl-2,3-dioleoylglycerol (SOO). As little as 10% of SOO in mixture with OOO slowed the clearance, and increasing proportions of SOO in OOO emulsions progressively slowed the removal of OOO and CO labels from plasma. With 50% and 100% SOO in the emulsions clearance was negligible. In emulsions containing the triacyl-sn-glycerols, 1,3-dimyristoyl-2-oleoylglycerol (MOM), 1,3-dipalmitoyl-2-oleoylglycerol (POP), 1-oleoyl-2,3-distearoylglycerol (OSS) or 1-palmitoyl-2-oleoyl-3-stearoylglycerol (POS), clearance rates of CO and OOO labels from plasma were significantly decreased compared with control OOO emulsions. With emulsions prepared with the triacylglycerols, 1-oleoyl-2,3-dimyristoylglycerol (OMM) and 1-oleoyl-2,3-dipalmitoylglycerol (OPP), clearances of CO label were significantly slower than with control OOO emulsions, while the removal of OOO label was not significantly affected. The uptake of CO label in the liver was decreased in conjunction with the lower rates of clearance of emulsion CO from the plasma. The clearance from plasma of 1,3-distearoyl-2-oleoylglycerol (SOS) emulsions was similar to the control OOO emulsions, but significantly more emulsion OOO label was taken up by the liver. Emulsions made with the triacylglycerols extracted from natural cocoa butter, which contained a high proportion of saturated acyl chains, were cleared similarly to the control OOO emulsions. Our findings indicate that the plasma clearance of triacylglycerol-rich lipoprotein particles depends upon the specific arrangements of the acyl chains of the constituent triacylglycerols, and not necessarily on the overall saturation of the triacylglycerols.(ABSTRACT TRUNCATED AT 400 WORDS)

The effect of monostearoylglycerol on the metabolism of chylomicron-like lipid emulsions injected intravenously in rats.

In rats, remnant particles derived from chylomicron-like emulsions containing 1,3-dioleoyl-2-stearoylglycerol (OSO) are removed from plasma more slowly than remnants derived from triolein emulsions. The effect associated with a saturated acyl chain at the glycerol 2-position could be reproduced by incorporating 2-stearoylglycerol (MS) in a triolein emulsion. When MS solubilized with rat albumin or in plasma was injected before the injection of a triolein emulsion, clearance of the triolein emulsion was unchanged. The metabolic fate of MS, monitored with 14C-labelled MS, was similar whether incorporated in triacylglycerol emulsion or injected independently. More than 95% of MS had disappeared from the circulation by 5 min after the injection and the radioactivity was found in liver, spleen, muscle and adipose tissue. Some MS label appeared in plasma triacylglycerol. Remnants made in vitro by incubating triolein or OSO emulsions with post-heparin plasma showed no differences in their disappearance from plasma. With OSO emulsion, the in vitro remnants were found to contain more MS than remnants made in vivo in hepatectomized rats. Simultaneous injections of mixtures containing OSO and triolein emulsions, or triolein emulsions with and without MS, each labelled with either [3H]cholesteryl oleate or [14C]cholesteryl oleate showed consistently slower remnant removal and decreased liver uptake of the emulsions containing OSO or MS. Affinity columns and immunodiffusion all indicated that there was no difference in the amounts of apolipoprotein E associated with OSO or triolein particles. The protein spectra of in vivo remnants derived from OSO and triolein emulsion were also similar when examined by SDS-PAGE and isoelectric focusing gels. Our results show that the effects due to OSO or MS are mediated by the presence of MS in the emulsion particle surface, while indirect effects expressed in plasma or liver are excluded. The precise mechanism of the effect remains to be established, but it does not correlate with measurable changes in the spectra of apolipoproteins associated with the emulsion remnants.

The effect of added monoacylglycerols on the removal from plasma of chylomicron-like emulsions injected intravenously in rats.

Lipid emulsions were prepared with compositions similar to the triacylglycerol-rich plasma lipoproteins, but also incorporating added small amounts of monoacylglycerols. Control emulsions without monoacylglycerol were metabolized similarly to natural chylomicrons or very-low-density lipoproteins when injected intravenously in rats. The emulsion triacylglycerols and cholesteryl esters were both removed rapidly from the bloodstream, with the removal rates of triacylglycerols faster than those of cholesteryl esters. Much of the removed cholesteryl ester was found in the liver, but only a small fraction of the triacylglycerol, consistent with hepatic uptake of the triacylglycerol-depleted remnants of the injected emulsion. Emulsions incorporating added monooleoylglycerol or stearic acid were metabolized similarly. Added 1- or 2-monostearoylglycerol had no effect on triacylglycerol removal from plasma, but the removal rate of cholesteryl esters was decreased and less cholesteryl ester was found in the liver. These effects are similar to those recently described when emulsions and chylomicrons contained triacylglycerols with a saturated acyl chain at the glycerol 2-position, suggesting that saturated monoacylglycerol produced by the action of lipoprotein lipase may cause triacylglycerol-depleted remnant particles to remain in the plasma instead of being rapidly taken up by the liver.

Plasma clearance of model lipoproteins containing saturated and polyunsaturated monoacylglycerols injected intravenously in the rat.

Triacylglycerols, with a saturated long-chain fatty acid at the glycerol-2-position, slow the clearance from plasma of remnants derived from injected chylomicrons and chylomicron-like emulsions. Slowing of remnant clearance also occurs when about 1% of monostearoylglycerol is added to a triolein chylomicron-like emulsion. We have now found that addition of monoacylglycerols, containing a saturated acyl chain from 12 to 20 carbons, slowed the plasma clearance and decreased the liver uptake of the remnants. In contrast, monoacylglycerols with unsaturated acyl chains were inconsistent in their effects on the remnant clearance. Monoarachidonin (M20:4) slowed remnant clearance comparable to that of saturated monoacylglycerols, monolinolenin (M18:3) and monolinolein (M18:2) were less effective, while monoolein had the least effect on remnant clearance. We have confirmed the defective remnant clearance in rats of injected emulsions containing saturated acyl chain by the using the diester-2-ether analogues of triolein and 1,3-dioleoyl-2-stearoylglycerol (OSO). Chylomicron-like lipid emulsions made with the ether analogues had clearance rates similar to their triester counterparts. Preformed remnants derived from emulsions of OSO, its ether analogue, and triolein emulsions or emulsions of triolein with approximately 1% saturated monoacylglycerols were prepared in hepatectomized rats. After intravenous injection into conscious recipient rats, these remnants were cleared from plasma similar to remnants traced in situ by lipolysis of injected chylomicron-like emulsions.