In vivo testing of crosslinked polyethers. II. Weight loss, IR analysis, and swelling behavior after implantation

As reported in Part I (In vivo testing of crosslinked polyethers. I. Tissue reactions and biodegradation, J. Biomed. Mater. Res., this issue, pp. 307-320), microscopical evaluation after implantation of crosslinked (co)polyethers in rats showed differences in the rate of biodegradation, depending on the presence of tertiary hydrogen atoms in the main chain and the hydrophilicity of the polyether system. In this article (Part II) the biostability will be discussed in terms of weight loss, the swelling behavior, and changes in the chemical structure of the crosslinked polyethers after implantation. The biostability increased in the order poly(POx) < poly(THF-co-OX) < poly(THF) for the relatively hydrophobic polyethers. This confirmed our hypothesis that the absence of tertiary hydrogen atoms would improve the biostability. On the other hand, signs of biodegradation were observed for all polyether system studied. Infrared surface analysis showed that biodegradation was triggered by oxidative attack on the polymeric chain, leading to the formation of carboxylic ester and acid groups. It also was found that in the THF-based (co)polyethers, α-methylene groups were more sensitive than β-methylene groups. For a hydrophilic poly(THF)/PEO blend, an increase in surface PEO content was found, which might be due to preferential degradation of the PEO domains

Knowledge, attitudes and practices of health professionals in management of pain in aids patients at Polokwane/ Mankweng Hospital complex, Limpopo Province

Includes bibliographical references.This study was initiated as part of a quality improvement project on pain management at Polokwane/Mankweng Hospital Complex (PMHC). This is the first part of the project, which involved a baseline study to assess the knowledge, attitude and practice of doctors working in the two hospitals in managing pain in HIV/AIDS patients. Admissions due to the AIDS epidemic have continued to rise over the years, with a quarter of admission in medical wards being attributed to AIDS related diseases1. The survey was conducted at Polokwane/Mankweng Hospital Complex. One hundred and twenty questionnaires were distributed, and 52% of the doctors returned the completed questionnaires. The objectives of the study were as follows: 1. To determine the level of knowledge of doctors in PMHC about pain in AIDS patients. 2. To determine the attitudes of doctors in PMHC regarding pain management in AIDS patients. 3. To determine their practice regarding prescribing analgesics for pain in AIDS patients. 4. To determine whether the level of knowledge and their attitudes affect their prescribing practice. The level of knowledge of doctors at PMHC is low compared to previous studies 2,3,4 with a mean of 46.92%. The level of knowledge for Oncologists is not better than other specialties. The oncologists do however have better knowledge of the WHO pain ladder compared to other specialties. The doctors (56.9%) are not familiar with the WHO pain ladder, which has been in existence for over 20 years. The doctors are aware that pain management is major problem (69.2%), and that one has to aim for complete pain relief (83.1%). Community Service doctors have been found to have the lowest mean score for level of knowledge (33.92%, SD=9.44) and level of attitude (52.39%, SD=17.81). Interns on the other hand had the highest mean score for the level of attitude (80.55%, SD=19.47) and knowledge (58.33; SD=17.07). 7 Most doctors still believe that the likelihood of patients developing addiction to morphine when given for chronic pain is moderate to high (67.7%). The demographic variables had no influence on the level of knowledge, level of attitude and the practice pattern. There was a positive correlation in the level of knowledge and the level of attitude (p=0.014), as well as the practice pattern (p=0.001), which is different from what other studies obtained. The level of attitude also correlated with practice pattern (p=0.0004). Although the study has limitations, important and interesting findings have come to the fore, and have to be acted upon. Management of chronic pain and palliative care has not been part of medical training in South Africa until recently, and is still a small part of the curriculum, if at all. The need for training of doctors in pain management and palliative is evident. The Limpopo Provincial Government and PMHC have to develop a strategy on how to address the identified gaps in the knowledge, attitude and practices of doctors

Simultaneous Analysis of Bioactive Markers from Orthosiphon Stamineus Benth Leaves Extracts by Reverse Phase High Performance Liquid Chromatography

Purpose: To develop a reverse phase high performance liquid chromatography (RP-HPLC) method for the analysis of the crude extracts of Orthosiphon stamineus.Methods: A simple and facile analytical method was developed using RP- HPLC with UV detection for the identification and quantitation of bioactive markers present in O. stamineus extracts. Four different bioactive markers were used for the analysis, namely, rosmarinic acid, orthosiphol-A, 3’-hydroxy-5, 6, 7,4’-tetramethoxyflavone (TMF) and 5, 6, 7, 3’, 4’-pentamethoxyflavone (sinensetin), using an isocratic mobile phase methanol: tetrahydrofuran: water (0.1% H3PO4) (55:5:40) on Nucleosil C-18 column (250 mm x 4.6 mm i.d., 5 ìm particle size) at a flow rate of 0.7 ml/min and detection at 330 nm with 30 min separation time.Results: The bioactive marker orthosiphol A was identified and isolated from the water extract of O. stamineus leaves. The standard calibration curves for the marker were linear in the range 0.01 - 500 ìg/ml with a regression coefficient (r2) > 0.9996. The recoveries of the four markers were in the range 83.2 to 106.4 % at relative standard deviation (RSD) values < 5 %. The limit of detection (LOD) and of quantification (LOQ) were 2 and 20 ng/ml, respectively.Conclusion: The developed method is simple, sensitive and specific for simultaneous determination of the indicated marker compounds either qualitatively or quantitatively, and may be used as a fingerprintprofile for the standardization of extractives or herbal medicines from O. stamineus

CAPITEL: Design and Implementation of a wireless 6 channel EMG measurement system for permanent in vivo use: in vitro results

Introduction Surface Electromyography of partial limb amputees is used to control prostheses. Implantable EMG systems offer a higher Signal to Noise Ratio (SNR) as well as improved muscle specificity, and a more convenient daily use. Material and methods We present a design for an implantable device (“implant”) with 6 channels, each suitable for an electrode array with 3 electrodes. The implant uses an ADS1298 analog front end with ADG2188 multiplexers for versatile electrode array configuration. The analog input is filtered with a balanced analog bandpass filter with corner frequencies of 30 and 800 Hz. The ADC sample rate is 2 KHz per channel, with 9 bits resolution. The dimensions of the PCB implant are 17.2 x 14.1x2.15 mm. To measure the SNR a sinusoidal signal with a peak to peak amplitude of 7 mV and a frequency of 200 Hz was applied to each input. To simulate muscle impedance, an equivalent muscle impedance model (Figure 1) was placed between the generator and each channel of the implant [1]. We have implemented two data transmission methods: wired duplex communication and wireless inductive link. The wired link is used to transfer raw data, while only the 6 EMG envelopes, with an update rate of 20 Hz, are sent via the wireless link. Results Each analog input channel performed with a SNR better than 52 dB, both for wired and wireless operation. Wired data was received successfully at 115200 bps and wireless data at 1080 bps. Discussion Our design achieves a high SNR and data rate. These early results are promising and we are packaging the PCBs for in-vivo testing. Conclusion We have demonstrated a very compact design suitable for the monitoring of 6 EMG channels, with options for raw data or EMG envelope transmission. [1] Kalvoy, H, 2009, doi: 10.1088/0967-3334/30/2/002

Clinical challenges in the co-management of diabetes mellitus and tuberculosis in southern Africa

Over the past 20 years, tuberculosis incidence in southern Africa has increased at an alarming rate, fuelled primarily by the human immunodeficiency virus epidemic. The emerging prevalence of diabetes mellitus in the region represents a new threat to tuberculosis control. The intersecting double burden is a cause for concern since diabetes mellitus increases the risk of tuberculosis and results in poor treatment outcomes. This review article discusses the evidence of a causal association between these two conditions, and examines the numerous clinical challenges that relate to tuberculosis and diabetes mellitus co-management. Diabetes is associated with a more advanced age and body weight in patients with tuberculosis, although not with a specific clinical presentation of tuberculosis. Rifampicin adversely alters glycaemic control by lowering the concentrations of most oral antidiabetic drugs. Poor glycaemic control, possibly exacerbated by tuberculosis and anti-tuberculous therapy, is an important contributing factor to tuberculosis case fatality and relapse. Clinicians need to be aware of these clinical and pharmacological challenges when co-managing these complex diseases.Keywords: diabetes, tuberculosis, rifampicin, co-management, southern Afric

Effect of Ascorbic Acid on Lipoprotein Lipase Activity

Baboons kept on hypovitaminotic C diets, but without clinical signs of scurvy, had significantly higher heart muscle lipoprotein lipase activity than baboons on vitamin C 34 mg/kg body mass/day. When the serum vitamin C levels were above 0,35 mg/100 ml the heart muscle lipoprotein lipase was repressed. Serum vitamin C levels below 0,35 mg/100 ml stimulated lipoprotein lipase to between 2 and 3 times the repressed value. Heart muscle lipoprotein lipase from baboons receiving dietary vitamin C was inhibited by 0,34 mM vitamin C in vitro, whereas heart muscle lipoprotein lipase from baboons on scorbutogenic diets were stimulated by addition of vitamin C in vitro.S. Afr. Med. J., 48, 511 (1974

On the Wiener-Hopf solution of water-wave interaction with a submerged elastic or poroelastic plate.

A solution to the problem of water-wave scattering by a semi-infinite submerged thin elastic plate, which is either porous or non-porous, is presented using the Wiener-Hopf technique. The derivation of the Wiener-Hopf equation is rather different from that which is used traditionally in water-waves problems, and it leads to the required equations directly. It is also shown how the solution can be computed straightforwardly using Cauchy-type integrals, which avoids the need to find the roots of the highly non-trivial dispersion equations. We illustrate the method with some numerical computations, focusing on the evolution of an incident wave pulse which illustrates the existence of two transmitted waves in the submerged plate system. The effect of the porosity is studied, and it is shown to influence the shorter-wavelength pulse much more strongly than the longer-wavelength pulse

Neodymium isotopic composition and concentration in the western North Atlantic Ocean: results from the GEOTRACES GA02 section

The neodymium (Nd) isotopic composition of seawater is commonly used as a proxy to study past changes in the thermohaline circulation. The modern database for such reconstructions is however poor and the understanding of the underlying processes is incomplete. Here we present new observational data for Nd isotopes and concentrations from twelve seawater depth profiles, which follow the flow path of North Atlantic Deep Water (NADW) from its formation region in the North Atlantic to the northern equatorial Atlantic. Samples were collected during two cruises constituting the northern part of the Dutch GEOTRACES transect GA02 in 2010. The results show that the different water masses in the subpolar North Atlantic Ocean, which ultimately constitute NADW, have the following Nd isotope characteristics: Upper Labrador Sea Water (ULSW), εNd = -14.2 ± 0.3; Labrador Sea Water (LSW), εNd = -13.7 ± 0.9; Northeast Atlantic Deep Water (NEADW), εNd = -12.5 ± 0.6; Northwest Atlantic Bottom Water (NWABW), εNd = -11.8 ± 1.4. In the subtropics, where these source water masses have mixed to form NADW, which is exported to the global ocean, upper-NADW is characterised by εNd values of -13.2 ± 1.0 (2sd) and lower-NADW exhibits values of εNd = -12.4 ± 0.4 (2sd). While both signatures overlap within error, the signature for lower-NADW is significantly more radiogenic than the traditionally used value for NADW (εNd = -13.5) due to the dominance of source waters from the Nordic Seas (NWABW and NEADW). Comparison between the concentration profiles and the corresponding Nd isotope profiles with other water mass properties such as salinity, silicate concentrations, neutral densities and chlorofluorocarbon (CFC) concentration provides novel insights into the geochemical cycle of Nd and reveals that different processes are necessary to account for the observed Nd characteristics in the subpolar and subtropical gyres and throughout the vertical water column. While our data set provides additional insights into the contribution of boundary exchange in areas of sediment resuspension, the results for open ocean seawater demonstrate, at an unprecedented level, the suitability of Nd isotopes to trace modern water masses in the strongly advecting western Atlantic Ocean