Cardiac signal estimation based on the arterial and venous pressure signals of a hemodialysis machine.

Continuous cardiac monitoring is usually not performed during hemodialysis treatment, although a majority of patients with kidney failure suffer from cardiovascular disease. In the present paper, a method is proposed for estimating a cardiac pressure signal by combining the arterial and the venous pressure sensor signals of the hemodialysis machine. The estimation is complicated by the periodic pressure disturbance caused by the peristaltic blood pump, with an amplitude much larger than that of the cardiac pressure signal. Using different techniques for combining the arterial and venous pressure signals, the performance is evaluated and compared to that of an earlier method which made use of the venous pressure only. The heart rate and the heartbeat occurrence times, determined from the estimated cardiac pressure signal, are compared to the corresponding quantities determined from a photoplethysmographic reference signal. Signals from 9 complete hemodialysis treatments were analyzed. For a heartbeat amplitude of 0.5 mmHg, the median absolute deviation between estimated and reference heart rate was 1.3 bpm when using the venous pressure signal only, but dropped to 0.6 bpm when combining the pressure signals. The results show that the proposed method offers superior estimation at low heartbeat amplitudes. Consequently, more patients can be successfully monitored during treatment without the need of extra sensors. The results are preliminary, and need to be verified on a separate dataset.

Identification of patients prone to hypotension during hemodialysis based on the analysis of cardiovascular signals.

Intradialytic hypotension (IDH) is a major complication during hemodialysis treatment, and therefore it is highly desirable to identify, at an early stage during treatment, whether the patient is prone to IDH. Heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity (BRS) were analyzed during the first 30 min of treatment to assess information on the autonomic nervous system. Using the sequential floating forward selection method and linear classification, the set of features with the best discriminative power was selected, resulting in an accuracy of 92.1%. Using a classifier based on the HRV features only, thereby avoiding that continuous blood pressure has to be recorded, accuracy decreased to 90.2%. The results suggest that an HRV-based classifier is useful for determining whether a patient is prone to IDH at the beginning of the treatment.

The effects of pathogen challenges on the performance of naïve and immune animals: the problem of prediction.

Predictive frameworks for performance under both physical and social stressors are available, but no general framework yet exists for predicting the performance of animals exposed to pathogens. The aim of this paper was to identify the key problems that would need to be solved to achieve this. Challenges of a range of hosts by a range of pathogens were reviewed to consider reductions in growth beyond those associated with reductions in voluntary food intake (VFI). Pair-feeding and marginal response studies identified the extent and mechanisms of how further reductions in growth occur beyond those caused by reduced VFI. Further reductions in growth depended on the pathogen, the host and the dose and were time dependent. In some instances the reduction in VFI fully explained the reduction in growth. Marginal response experiments showed increased maintenance requirements during exposure to pathogens, but these were different for specific amino acids. There were no clear effects on marginal efficiency. Innate immune functions, repair of damaged tissue and expression of acquired immunity caused significant but variable increases in protein (amino acid) requirements. More resistant genotypes had greater requirements for mounting immune responses. The partitioning of protein (amino acids) was found to be different during pathogen challenges. Prediction of the requirements and partitioning of amino acids between growth and immune functions appears to be a crucial problem to solve in order to predict performance during pathogen challenges of different kinds and doses. The problems of accounting for reductions in performance during pathogen challenges that are described here provide a useful starting point for future modelling and experimental solutions.

A model for predicting feed intake of growing animals during exposure to pathogens.

A general model is proposed for predicting the effects of subclinical pathogen challenges of different doses and virulence on the relative feed intake (RFI) of animals. The RFI is defined as the feed intake (FI, kg/d) of the animal challenged by a pathogen divided by its FI in the same state had it not been challenged. Actual FI can be predicted from the RFI and the animal's state. The RFI was assumed to be affected only when animals were naïve to a particular pathogen (i.e., had not previously experienced it) and when the challenge dose was above a predetermined threshold. The model is for the period from recognition of a pathogen through acquisition and subsequent expression of immunity. The way in which RFI changes with time is described by 5 main parameters and is based on data for RFI during different pathogen challenges of a range of hosts. Lag time (L, d) is the delay from a pathogen challenge until any effects on RFI are seen. Reduction time (R, d) describes the time it takes for the lowest value of RFI (lambda) to be achieved. The duration time (D, d) describes the time that lambda is maintained for, and rho (RFI/d) describes the rate of recovery of RFI until RFI = 1. There is no compensatory intake, and RFI is always < or = 1. The effects of host resistance on the values of the model parameters are proposed. Attempts were made to parameterize the model; when data were scarce, initial parameter values were derived on conceptual grounds. Predictions of the effects of pathogen dose, virulence, and host resistance are described and discussed. When comparing the responses in RFI for different genotypes, it is crucial to define the pathogen challenge (in terms of dose and virulence) and the degree of resistance of different hosts. Possible interactions between dose, virulence, and resistance were explored. Feed intake of healthy and challenged animals, at a time, may be different once the challenged animal has recovered (RFI = 1). The issue of reductions in FI during pathogen challenges is important for nutritionist and animal breeders. The large variation that has been observed for reductions in FI during pathogen challenges may be a viable point of selection. The points highlighted will aid selection strategies by quantifying the effects of pathogen dose and virulence, and time, on the FI of challenged animals. The proposed model may be integrated with other models of growth to predict animal performance during exposure to pathogens.

Oldenlandia affinis (R&S) DC. A plant containing uteroactive peptides used in African traditional medicine.

A review of the geographical distribution, clinical use, biological activity and phytochemistry of Oldenlandia affinis (R&S) DC. is presented. During an inventory of medicinal plants in northern Congo/Brazzaville and south-western Central African Republic in 1962, 196 different species were registered, one of which was O. affinis used for the facilitation of childbirth. A medical team working in Luluabourg (Kananga) in Congo during the troubled period in 1960, discovered also the traditional use of the same plant as an oxitocic agent during labour. The plant was collected and the uterotonic substances isolated. Cyclic peptides (called Kalata-peptides) were described, and the main peptide, B1, was subjected to pharmacological and chemical investigations. Later the three-dimensional structure of the peptide was determined. Similar cyclic peptides have been isolated also from other plants in the Rubiaceae family like Chassalia pasvifoloia and Psychotria longipes, and from Viola species: Viola tricolor L. and Viola arvensis Murray. Some of these peptides, included Kalata-peptide B1, have been shown to hold antimicrobial activity. They have recently been synthesized, and they may represent a starting point for the design of new peptide antibiotics.

Use of visual analogue scale measurements (VAS) to asses the effectiveness of standardized Andrographis paniculata extract SHA-10 in reducing the symptoms of common cold. A randomized double blind-placebo study.

The objective of our study was to measure the effectiveness of Andrographis paniculata SHA-10 extract in reducing the prevalence and intensity of symptoms and signs of common cold as compared with a placebo. A group of 158 adult patients of both sexes completed the randomized double blind study in Valdivia, Chile. The patients were divided in two equal size groups, one of which received Andrographis paniculata dried extract (1200 mg/day) and the other a placebo during a period of 5 days. Evaluations for efficacy were performed by the patient at day 0, 2, and 4 of the treatment; each completed a self-evaluation (VAS) sheet with the following parameters: headache, tiredness, earache, sleeplessness, sore throat, nasal secretion, phlegm, frequency and intensity of cough. In order to quantify the magnitude of the reduction in the prevalence and intensity of the signs and symptoms of common cold, the risk (Odds Ratio = OR) was calculated using a logistic regression model. At day 2 of treatment a significant decrease in the intensity of the symptoms of tiredness (OR = 1.28; 95% CI 1.07-1.53), sleeplessness (OR = 1.71; 95% CI 1.38-2.11), sore throat (OR = 2.3; 95% CI 1.69-3.14) and nasal secretion (OR = 2.51; 95% CI 1.82-3.46) was observed in the Andrographis SHA-10 group as compared with the placebo group. At day 4, a significant decrease in the intensity of all symptoms was observed for the Andrographis paniculata group. The higher OR values were for the following parameters: sore throat (OR = 3.59; 95% CI 2.04-5.35), nasal secretion (OR = 3.27; 95% CI 2.31-4.62) and earache (OR = 3.11; 95% CI 2.01-4.80) for Andrographis paniculata treatment over placebo, respectively. It is concluded that Andrographis paniculata had a high degree of effectiveness in reducing the prevalence and intensity of the symptoms in uncomplicated common cold beginning at day two of treatment. No adverse effects were observed or reported.

Ethnobotanical inventory of medicinal plants used by the Guaymi Indians in western Panama. Part II.

A list of newly identified plants is presented to supplement Part I (Joly et al. (1987) Journal of Ethnopharmacology 20, 145-171). A comparative analysis is made between our work and two other recent inventories of plants used by the Guaymi Indians of Panama and Costa Rica. As in Part I, the results of a literature survey are also provided, including medicinal uses, known constituents and pharmacological effects.

Inhibitory effect of extract of Ipomoea pes-caprae on guinea-pig ileal smooth muscle.

An extract of the plant Ipomoea pes-caprae, used in Thailand as a folk remedy for treating dermatitis caused by jellyfish and Portuguese man-of-war, has been tested for antagonistic activity against histamine, acetylcholine, bradykinin and barium chloride on the isolated guinea-pig ileum. The extract reversibly inhibited the contraction induced by all the spasmogens in a concentration-dependent manner and decreased both the slope and the maximal response of the concentration response curves. It is not likely that the extract specifically interferes at the receptor level. It may be due to the direct action of the extract on the ileal smooth muscle.

Ethnobotanical inventory of medicinal plants used by the Guaymi Indians in western Panama. Part I.

Plants used by Guaymi "Curanderos" in Western Panama (Bocas del Toro and Chiriquí) are listed. Results of a literature survey are also reported, including medical use, known constituents and pharmacological effects.

Muscle relaxant activity and hypotensive activity of some Tabernaemontana alkaloids.

Stemmadenine, the major alkaloid from the seeds of Tabernaemontana dichotoma, showed hypotensive activity and weak muscle relaxant activity. Perivine, vobasine, coronaridine and dichomine, some of the alkaloids found in the leaves, fruits and bark of T. dichotoma, also showed hypotensive and muscle relaxant activity.