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.     

Visual evoked responses in ethambutol induced optic neuritis

Pattern evoked responses were recorded in 46 patients of tuberculosis on ethambutol and 16 healthy subjects. Deterioration in visual acuity was documented in two patients (4.3%). P100 latency was delayed in 16 cases (34.8%), while in 12 patients (26.1%) both latency and amplitude were affected. A cut off latency value of > or = 140 ms was associated with ophthalmological findings. The incidence of subclinical toxicity as detected by visual evoked response (VER) was higher in older subjects, patients on higher doses of ethambutol (> or = 20 mg/kg/day) and longer duration of treatment. Of two cases with objective ocular signs, one who reported for follow up after two months had recovered completely after stopping ethambutol. Recording of VER is an extremely useful objective test for subclinical optic nerve damage.     

Outcomes of unrelated umbilical cord blood transplantation for X-linked adrenoleukodystrophy.

Adrenoleukodystrophy (ALD) is an X-linked disorder caused by a defect in the metabolism of long chain fatty acids leading to demyelination, neurodegeneration, and death. The disease typically presents in young boys and adolescent boys. Allogeneic bone marrow transplantation has been used to halt progression of the disease. However, many patients lack suitable HLA- matched related donors and must rely on unmatched donors for a source of stem cells. The purpose of this study was to evaluate outcomes of unrelated donor umbilical cord blood transplantation after chemotherapy-based myeloablative conditioning and retrospectively determine if baseline studies correlate and help predict outcome. Between November 22, 1996, and November 3, 2005, 12 boys with X-linked ALD who lacked HL- matched related donors were referred to Duke University Medical Center for transplantation. These children were conditioned with myeloablative therapy including busulfan, cyclophosphamide, and antithymocyte globulin before receiving umbilical cord-blood transplants from unrelated donors. Baseline studies of neurophysiologic, neuroimaging, and neurodevelopmental status were performed and patients were subsequently evaluated for survival, engraftment, graft-versus-host disease, and neurodevelopmental outcomes. A substudy evaluated whether baseline neuroimaging and neurophysiologic studies correlated with cognitive and motor function and if these studies were predictive of posttransplantation outcomes. The umbilical cord blood grafts had normal levels of very long chain fatty acids. They delivered a median of 6.98 x 10(7) nucleated cells per kilogram of recipient body weight and were discordant for up to 4 of 6 HLA markers. Neutrophil engraftment occurred at a median of 22.9 days after transplantation. Three patients had grade II-IV acute graft-versus-host disease; 2 had extensive chronic graft-versus-host disease. Cumulative incidence of overall survival of the group at 6 months is 66.7% (95% confidence interval 39.9-93.3%). Median follow-up was 3.3 years (range 12 days to 6.3 years). As previously reported with bone marrow transplantation, symptomatic patients faired poorly with lower survival and rapid deterioration of neurologic function. This study included 3 patients transplanted at a very young age (2.6-3.5 years) before the onset of clinical symptoms who continue to develop at a normal rate for 3-5 years posttransplant. Although baseline Loes scores correlated with cognitive and motor outcome, neurophysiologic studies failed to show statistically significant differences. Transplantation of boys with X-linked ALD using partial HLA-matched umbilical cord blood yields similar results to those previously reported after bone marrow transplantation. Superior outcomes were seen in neurologically asymptomatic boys less than 3.5 years of age at the time of transplantation. Baseline Loes scores were a strong predictor of cognitive and motor outcome.     

Spiracular indices in Anopheles stephensi: a taxonomic tool to identify ecological variants

Thoracic spiracle length and its index was examined for their ability to discriminate two ecological variants, type form and mysorensis, of Anopheles stephensi in the adult stage. The type form is exclusively domestic in all seasons, whereas the mysorensis variant occupies the outdoor niche during monsoon and postmonsoon seasons, with spillover into domestic sites during summer ecological stress periods. A statistically significant co-relation was established between the ridge count of the egg and two adult measurements, the thoracic spiracle length, and the spiracular index. In An. stephensi type form, average spiracle length was 0.11-0.12 mm and average spiracular index was 8.09-9.23, whereas in mysorensis, the corresponding figures were 0.09-0.10 mm and 6.82-7.60. These parameters showed consistent variations in population of mosquitoes that emerged during monsoon and summer season. The thoracic lengths in both variants remained constant, and only spiracular lengths showed fluctuations in three seasonal populations. These measures provide discrimination of adult variants--identifications that are essential in malaria control programs.     

Recombinant human parvovirus B19 vectors

In an attempt to exploit the remarkable tissue-tropism of the human parvovirus B19 to target human hematopoietic cells of the erythroid lineage, recombinant human adeno-associated virus 2 genomes were encapsidated in parvovirus B19 capsids. Although efficient transduction of primary human hematopoietic cells in the erythroid lineage occurred, a low-level of transgene expression in non-erythroid cells was also detected. These studies suggest that cell surface expression of P antigen, the primary receptor for parvovirus B19, is necessary but not sufficient for parvovirus B19 vector-mediated transduction of human hematopoietic cells. These studies also suggest the existence of a putative cell surface co-receptor, which is required for successful infection of human hematopoietic cells by parvovirus B19.     

Fever-like temperature induces maturation of dendritic cells through induction of hsp90

Fever is a phylogenetically conserved biological phenomenon and a common consequence of infection. Here, we examine in vitro and in vivo the effect of febrile temperature on dendritic cells (DC), a key antigen-presenting cell in the immune system. Elevated temperatures are observed to cause immature DC to mature, specifically through elevation of intracellular levels of hsp90. Surprisingly, even brief exposure to elevated temperatures has a powerful effect on the immunostimulatory capacity of DC. These results bear on the mechanisms of the salutary effects of fever as well as of behavioral elevations of temperature such as saunas and warm blankets.     

Food Allergy Herbal Formula-1 (FAHF-1) blocks peanut-induced anaphylaxis in a murine model

BACKGROUND: Peanut allergy is a major cause of fatal and near-fatal anaphylactic reactions to foods. There is no curative therapy for this condition. Traditional Chinese medicines have been reported to have antiallergic properties, which might be useful for treating peanut allergy. OBJECTIVE: The purpose of this study was to investigate the effects of a Chinese herbal formula, FAHF-1, on peanut anaphylactic reactions in a mouse model of peanut allergy. METHODS: Mice were sensitized with freshly ground whole peanut in the presence of cholera toxin and boosted 1 and 3 weeks later. FAHF-1 treatment was initiated 1 week later and continued for 7 weeks. After treatment, mice were challenged with peanut, and anaphylactic symptoms, body temperatures, and plasma histamine and IgE levels were measured. T-cell proliferative responses and cytokine production were also determined. RESULTS: FAHF-1 completely blocked peanut-induced anaphylactic symptoms and markedly reduced mast cell degranulation and histamine release. Peanut-specific serum IgE levels were significantly reduced by 2 weeks of treatment at the time of challenge, and they remained lower 4 weeks after discontinuation of treatment. FAHF-1 significantly reduced peanut-induced lymphocyte proliferation as well as IL-4, IL-5, and IL-13 synthesis but not IFN-gamma synthesis. No toxic effects on liver or kidney functions were observed, nor was there any overall immune suppression. CONCLUSION: FAHF-1 protected peanut-sensitized mice from anaphylactic reactions and significantly reversed established IgE-mediated peanut allergy. This suggests that FAHF-1 might prove valuable for the treatment of peanut allergy.