Low delay rate adaptive pacemaker using FPGA embedded piezoelectric sensor

Abstract

This paper presents the hardware implementation of low delay, power-efficient, rate-adaptive dual-chamber pacemaker (RDPM) using a piezoelectric sensor. Rate adaptive pacemaker has the ability to sense the patient’s activity by means of some special sensors and it controls the pacing rate according to the patient’s activity. Ideally, there should be no delay between sensing and the subsequent pacing operation performed by the pacemaker. However, delay in the responses of various components in the circuitry produces an accumulative delay effect in any practical circuit. Physical activity and the physiological needs of the patient can be easily adapted by the rate-responsive pacemakers using a wide range of sensor information. The piezo-electric sensor recognises the pressure on human muscles because of physical activity and converts it to an electrical signal, which is received by the pulse generator of the pacemaker. When the patient is in the rest mode, the heart rate is the only parameter that is to be detected by the pacemaker. Thus, the heart rate and the physical activity both are the inevitable parameters for the design of RDPM. Performance analysis of the proposed RDPM shows a significant reduction in the delay between sensing and pacing. Device utility analysis shows that the proposed design not only requires lesser memory but also reduces the number of components on the chip. Therefore, it becomes very clear that the proposed pacemaker design will consume much lesser power.     

Evoked potential changes in ischaemic myelopathy

Somatosensory evoked potentials are employed in the intraoperative monitoring but there is paucity of information about the motor evoked potentials (MEP) in spinal cord ischaemia. Two patients aged 9 and 4 years developed paraplegia following surgery for coarctation of aorta. The aortic cross clamping time in these patients was 100 min and 30 min. respectively. The patient with longer clamping time had flaccid paraplegia and lower limb MEPs were not recordable; whereas the patient with shorter clamping time had spastic paraparesis and prolonged CMCT to right lower limb. The latter patient improved significantly. Tibial SEPs were normal in both the patients. Our results suggest that MEP may have a greater role than SEP in documenting and prognosticating ischaemic myelopathy.     

Molecular characterization of a carnation etched ring virus isolate from India

Incidence of the Carnation etched ring virus (CERV), the only DNA virus reported to date on carnation, was investigated by a bioassay using a partially purified virus as inoculum and then by a double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). Out of 61 carnation cultivars analyzed 41 (67%) were found positive. The virus positivity was verified by polymerase chain reaction (PCR) and nucleotide sequencing. The amplified 1349 bp fragment was by about 98% and 96% identical with respect to coat protein (CP) and enzymatic polyprotein genes, respectively, as compared to the sequences available in the database. In terms of amino acid sequence similarity, the homology values were 99% and 97%, respectively. Comparison with other caulimoviruses revealed that CERV is most closely related to the Cauliflower mosaic virus (CaMV). High genetic stability of CERV may be attributed to the fact that it has evolved from the same initial sequence in an original host. Because of global market of cut flowers and vegetative propagation it has been dispersed around the world.     

Genetic mapping of genes regulating the thymus size in back-cross rats between the laboratory BUF/Mna strain and the MITE strain derived from the wild rat, Rattus norvegicus

The thymoma prone BUF/Mna (B) rat is a useful model for Studying the genes responsible for thymus enlargement during the stage of young growth. Among the strains of rats, B rats have the largest thymuses at al stages of life. A locus, Ten-1 , which contributes to thymus enlargement in back-cross (BC) rats between the B and WKY/NCrj (W) strains, was mapped on chromosome 1. To determine the precise location of the bus, (B×(B×MITE)F1) BC rats were generated by crossing the B strain with the Inbred MITE (M) strain, which was established from captured, Japanese wild rats, and were examined by linkage study using polymerase chain reaction with 67 microsatellite markers. Linkages with thymus enlargements were found In genotypes of seven markers, BSIS, LSN, MYL2, IGF2, PBPC2, D1Mgh11 , and D1Mit6 , by X^2-test and Student's t -test, which confirmed the presence of the genetic locus associated with thymus enlargement, Ten-1 , in this region. Paradoxically, a suppressive locus, Tsu-1 , to thymus enlargement was also found on chromosome 3, showing linkages of phenotype of the small thymus with genotypes of SCN2A, CAT D3Mit16 , and D3Mit13 . By analyses of mapmaker/exp and mapmaker/qtl, Ten-1 was mapped at 4.6 cM proximal from IGF2 locus on chromosome 1 and Tsu-1 at 4.0 cM proximal from CAT locus on chromosome 3, respectively.     

Age-related changes in the total protein in the brain of Periplaneta americana (L.)

Quantitative changes in the total protein in the brain of aging male and female Periplaneta americana have been observed. A significant increase of total protein and neurosecretory cells in the brain up to 5 months, followed by a considerable decline in later age, points to a direct relationship between the neurosecretory cell number and reproductive phenomenon. Higher total protein concentration and cell number maintain reproduction up to 5 months while a decline after 6 months of adult life adversly affects reproduction. This suggests that neurosecretory cell number and protein concentration are related to reproduction and thereby aging.     

Role of diurnal variation and receptor specificity in the opioidergic regulation of food intake in free-fed and food-deprived rats.

The effects of opioid agonists, morphine (MOR) and ketocyclazocine (KCZ), and antagonists, naltrexone (NALTX) and Mr2266, were investigated on food intake under various conditions, i.e., during light and dark phases of diurnal cycle and free-fed and fasting states in rats. NALTX showed a greater anorexic effect during dark phase, whereas Mr2266 produced such effect during light phase. This suggests that mu-receptors play a major role during dark phase while kappa-receptors are more important in light phase. The comparison of effects of different opioidergic drugs in fasted and free-fed rats showed that NALTX and Mr2266 reduced the elevated basal food intake in 18-h fasted rats to free-fed control levels. Therefore, it appears that enhanced endogenous mu- and kappa-directed neural mechanisms are one of the factors responsible for enhancing food intake in fasted rats. Differential role of MOR and KCZ on food intake in free-fed and fasted rats is also indicated in our study. Both agonists produced a biphasic response in fasted rats, i.e., hyperphagia (0-1 h) followed by hypophagia (1-6 h). However, a generalized hyperphagic effect is observed in free-fed rats (except during 3-6 h by MOR). The initial hyperphagic effect is more prominent in fasted rats which may be due to additive effects of endopioid mechanisms. Specificity of the response at various intervals is confirmed by blockade with NALTX and Mr2266. NALTX appears more potent than Mr2266 in antagonising the effects of MOR but markedly less potent than Mr2266 in inhibiting the effects of KCZ. This suggests that both MOR and KCZ have a mu as well as kappa component in food intake response.     

Osmoregulation in a parasitic nematode, Setaria cervi

Studies on osmotic and ionic regulation in Setaria cervi indicate that it can osmoregulate in hypertonic solutions but not in hypotonic solutions. The depression of the freezing point (delta degrees C) of host's peritoneal fluid was -0.71 degrees C.