Search PubMed⌕ Search

Biomedical subjects

N Prasad

Publications and source records attributed to N Prasad.

At least 91 records · Page 5Linked to original sources
PubMed1988

Power spectral analyses of inspiratory activities in neonatal pigs.

In anesthetized neonatal pigs, spectral analyses were done for inspiratory nerve and neuronal activities. Peaks in power spectra of phrenic roots were observed at high frequencies and at medium frequencies. In contrast, peaks in recurrent laryngeal and hypoglossal nerve spectra were found only at medium frequencies. Significant coherence estimates were obtained only at medium frequencies, indicating that different motoneuron pools share inputs from a common neural oscillator.

Action Potentials↗
PubMed1988

Giardia duodenalis: enhanced growth in cell culture.

Growth of Giardia duodenalis in broth and in animals has been studied in considerable detail. In contrast, the kinetics of growth in cell culture have been little evaluated. In this study, in vitro growth of G. duodenalis was evaluated in cell culture, primarily using mouse McCoy cells in vials. The media used were Giardia broth (TYI-G), Trichomonas vaginalis broth (TYI-T), and standard cell culture media (CMGA) alone and in combination (2 parts by volume CMGA to one part of TYI broth). Addition of cell culture enhanced the sensitivity of the systems in detecting low numbers of G. duodenalis. Growth was identified consistently with inocula less than or equal to 10/ml, and often with a calculated 10-1/ml inoculum with CMGA/TYI-T and CMGA/TYI-G with cells, and with TYI-G with and without cells. The 2 preferred systems for sensitivity and growth were CMGA/TYI-G with cells and TYI-G with cells. The pH fell minimally in the growth systems and, if CMGA was in the media, cell monolayers remained intact and viable throughout the experiment. In preliminary experiments, cell cultures did not allow growth of one strain of G. muris. These cell culture systems may be useful for detection of low numbers of non-laboratory adapted trophozoites, and should be useful in evaluating the interaction of G. dudodenalis with cells in culture.

Animals↗
PubMed1988

Factors affecting central inspiratory modulation of hypoglossal motoneuron activity in newborn pigs.

In newborn pigs (4-6 days old), recordings of efferent whole hypoglossal and phrenic nerve discharges were obtained during hyperoxia (or normoxia) and during hypoxia, before and after bilateral vagotomy. With intact vagi, spontaneous hypoglossal inspiratory activity was not observed and was not elicited by either spontaneous changes of electroencephalogram (EEG) or hypoxic stimulation (15% O2 in N2). After bilateral vagotomy, some animals had episodes of spontaneous hypoglossal inspiratory activity; power spectral analysis of EEG demonstrated that this inspiratory activity appeared synchronously with shifts of major peaks in EEG spectra from the delta band (0.5-3.5 Hz) to the theta band (3.5-7.0 Hz). Hypoglossal inspiratory discharges were also elicited by hypoxic stimulation and usually had a decrementing discharge pattern; in some cases, this activity had an augmenting discharge pattern. Our results suggest that hypoglossal motoneurons are poorly modulated by central inspiratory drive, requiring additional facilitatory influences, i.e. corticobulbar, intra-bulbar, chemical drive, before such modulation is observed.

Animals↗
PubMed1987

Effects of MR imaging on murine natural killer cell cytotoxicity.

To determine the effect of MR imaging on the immune system, 21 male C57BL/6 X DBA/2 F1 mice were exposed to MR imaging at a field strength of 0.15 T for 2 hr. Another nine mice (controls) were sham exposed for the same amount of time. Mice were sacrificed and their spleens removed 24, 72, and 144 hr after the exposure (MR or sham). Spleen cell suspensions were passed over nylon wool columns and then used as effector cells in a short-term natural killer cell cytotoxicity assay with 51Cr-labeled YAC-1 cells as target cells. The results showed no evidence of decreased cytotoxicity due to exposure to MR. On the contrary, at all three times after exposure and for all target-to-effector cell ratios, mean cytotoxicity was greater for MR-exposed groups than for sham-exposed groups. The results show that MR exposure has no adverse effect on the immune system, as evidenced by natural killer cell activity.

Animals↗
PubMed1984

Effect of nuclear magnetic resonance on chromosomes of mouse bone marrow cells.

Three groups of six male Balb/c mice, subjected to 30 MHz continuous wave NMR exposure in a static magnetic field of 7.05 K Gauss for one hour, were each compared to another group of ten unexposed mice with respect to chromatid and chromosomal aberrations. The exposed groups were sacrificed at two hours, 24 hours and 48 hours following NMR exposure respectively. Control mice were sacrificed 24 hours after sham-exposure. All groups had approximately 0.02 apparent aberrations per cell. These apparent aberrations were in the form of metacentric chromosomes, possibly resulting from a union of chromosomes at their centromeres or possibly simply chromosomes in association. The results are consistent with earlier in vitro findings that NMR exposure causes no adverse cytogenetic effects.

Animals↗
PubMed1984

Crown area as an indicator of changing crown size in human pre-natal teeth.

This study deals with correlations of tooth size in human primary teeth. Traditionally, mesiodistal or buccolingual measurements have been used to express crown size. However, in this study, crown area was used as a reference parameter. Graphic reconstructions of 38 histologically prepared human fetuses with Crown-Rump Length (CRL) between 54 and 280 mm were used to obtain linear and area measurements. Based on clinical records and physical examinations, these fetuses were considered typical-for-age, or "normal". Correlation matrices indicated high levels of concordance among all developing deciduous tooth crowns and arch measurements. It was concluded that crown area is a statistically better trait to use in comparison of teeth rather than the traditional mesiodistal measurement.

Body Height↗
PubMed1983

Identification of accessory bile ducts at cholecystectomy.

The presence of accessory channels between the liver and extrahepatic bile ducts has long been recognised by anatomists and the division of such ducts may be a cause of bile leakage following cholecystectomy. However, visualisation of accessory bile ducts at operation is difficult as they are often small and sometimes less than 1 mm in diameter. Cholangiography has been used to help in the identification of accessory ducts in 50 patients included in a prospective trial. X-rays were taken after dissection of the gall bladder from its bed and extravasation of contrast was seen on five occasions (10%) suggesting leakage from divided accessory ducts. The identification of damage to accessory bile ducts in 10% of patients suggests that this may occur more frequently than previously supposed.

Bile Ducts↗
PubMed1982

Effect of nuclear magnetic resonance on early stages of amphibian development.

Frog spermatozoa, fertilized eggs (during second meiotic division), and embryos (during cleavage) were subjected separately to 30 MHz continuous wave NMR exposure in a static magnetic field of 7.05 kG for 20 min and were compared to unexposed groups, at similar stages, with respect to damage in genetic material, interference with meiotic cell division, and impairment in the development of embryos. No significant differences were observed following treatment suggesting that NMR exposure, at the dose used, does not cause detectable adverse effects in this amphibian.

Animals↗
PubMed1980

Lymphocyte replication in lung cancer patients undergoing radiotherapy.

In vivo and in vitro survival and response of lymphocytes were studied in 12 lung cancer patients before, during and following radiotherapy, and comparisons were made to data from 20 healthy control subjects. Lymphocyte counts of lung cancer patients prior to radiotherapy did not differ significantly from those of control subjects. Following radiotherapy, lymphocyte counts were significantly reduced. The in vitro survival of lymphocytes from lung cancer patients prior to radiotherapy was lower than that of normal controls. Radiation treatment had no effect on lymphocyte survival in vitro. PHA-stimulated lymphoblast formation in lung cancer patients prior to radiotherapy did not differ from that of normal controls, but decreased significantly during radiotherapy.

Cell Survival↗
PubMed1980

Effect of dimethyl sulfoxide on hematopoietic stem cells in mice.

The effects of dimethyl sulfoxide (DMSO) were studied in irradiated BALB/c mice to see if DMSO has a stimulatory effect on hematopoietic stem cells. The spleen colony forming technique was employed. DMSO given after a lethal dose of radiation enhanced post-irradiation recovery and survival. The erythroid to granuloid spleen colony ratio was higher in the DMSO treated group compared to the controls. There was some evidence of an increase in the endogenous formation of erythroid colonies after DMSO treatment (0.38%). However, DMSO had no effect on exogenous erythroid colony formation; rather, it inhibited granuloid differentiation.

Animals↗
PubMed1979

Aryl hydrocarbon hydroxylase inducibility in lung cancer patients undergoing radiotherapy.

Aryl hydrocarbon hydroxylase (AHH) inducibility was studied in cultured lymphocytes from 21 healthy control subjects and from 15 lung cancer patients selected for radiation therapy. AHH inducibility of the patients was measured prior to, during and at the end of radiation therapy. Four of 15 patients had values comparable to the healthy controls. Cellular DNA and protein measurements of cultured lymphocytes were the same for patients and healthy controls. There was no significant difference in the percentage of lymphoblast formation and percentage of cell survival between the two groups. Radiation therapy reduces the number of lymphocytes in vivo and the amount of lymphoblast formation in vitro. AHH inducibulity is signifcantly lowered by radiation in the patients who had very high inducibility at pre-treatment level. DNA and protein contents of cultured lymphocytes did not change during radiation therapy.

Aged↗
PubMed1979

Aryl hydrocarbon hydroxylase inducibility and lymphoblast formation in lung cancer patients.

Aryl hydrocarbon hydroxylase (AHH) inducibility and lymphoblast formation were studied in lymphocytes from healthy control subjects and from lung cancer patients undergoing radiotherapy. The relationship between AHH inducibility and percentage lymphoblasts was statistically significant only for the pre-treatment patients (r = 0.598; p less than 0.05). In the control group and in patients undergoing radiotherapy the correlation between AHH inducibility and lymphoblast formation was positive but statistically it was not significant. Our data do not suggest a linear relationship between AHH inducibility and lymphoblast formation.

Aryl Hydrocarbon Hydroxylases↗