A bioacoustic method for timing of respiration at cardiac investigations

At cardiac investigations Doppler echocardiography is an established technique for the recording of intracardial and intravascular flow velocities. Transvalvular and venous flows are, however, markedly influenced by respiration. Since the start of inspiration is the important time of reference, accurate recording of the respiratory phase is important when analysing these flow velocities. A bioacoustic technique was therefore adopted to meet this demand and was tested in 10 normal subjects. Oesophageal balloon technique was used as a reference, and the bioacoustic technique was compared with a respiratory inductive plethysmograph. The average delay for the acoustic sensor signal compared to the oesophageal pressure changes was 205 +/- 46 (SD) ms, ranging from 160 to 320 ms for normal breathing, and is comparable to that of the respiratory inductive plethysmograph (210 +/- 90 ms). The bioacoustic technique is easier to apply than the respiratory inductive plethysmograph. The sensitivity to disturbances can be further reduced by signal processing and the method has clinical potential for the future.

The shape of the proximal isovelocity surface area varies with regurgitant orifice size and distance from orifice: computer simulation and model experiments with color M-mode technique

The hemispheric proximal isovelocity surface area method for quantification of mitral regurgitant flow (i.e., Qc = 2 pi r2v), where 2 pi r2 is the surface area and v is the velocity at radius r, was investigated as distance from the orifice was increased. Computer simulations and steady flow model experiments were performed for orifices of 4, 6, and 8 mm. Flow rates derived from the centerline velocity and hemispheric assumption were compared with true flow rates. Proximal isovelocity surface area shape varied as distance from each orifice was increased and could only be approximated from the hemispheric equation when a certain distance was exceeded: > 7, > 10, and > 12 mm for the 4, 6, and 8 mm orifices, respectively. Prediction of relative error showed that the best radial zone at which to make measurements was 5 to 9, 6 to 14 and 7 to 17 mm for the 4, 6, and 8 mm orifices, respectively. Although effects of a nonhemispheric shape could be compensated for by use of a correction factor, a radius of 8 to 9 mm can be recommended without the use of a correction factor over all orifices studied if a deviation in calculated as compared with true flow of 15% is considered acceptable. These measurements therefore have implications for the technique in clinical practice.

Problems in timing of respiration with the nasal thermistor technique

When one analyzes transvalvular and venous flow velocity patterns, it is important to relate them to respiration. For this reason a nasal thermistor technique is often used, although it is known that this signal is delayed in relation to intrathoracic pressure changes. The magnitude and variation in delay have not been investigated previously and were, therefore, studied in a model experiment in 10 normal subjects, in 10 patients with obstructive, and in 10 patients with restrictive pulmonary disease. Esophageal pressure variations measured with an air-filled balloon served as a gold standard for intrathoracic pressure changes. During basal conditions there was, for both patient groups and normal subjects, a considerable delay of the thermistor signal. The average delay for all subjects was 370 msec with a wide variation (from 120 to 720 msec). At higher breathing frequencies the delay shortened to 310 msec (P < 0.01) but there was still a wide variation (ranging from 200 to 470 msec). Theoretic calculations show that the delay caused by the respiratory system accounts for only a minor portion of the total delay. Model experiments confirmed that the response characteristics of the thermistor probes limit the accuracy in timing of respiration. The total delay with the investigated thermistor technique is too long and variable to fulfil clinical demands.

[Effects of Panax notoginseng saponins on monophasic action potentials of heart and automaticity and contractility of isolated atria]

The effects of Panax notoginseng saponins (PNS) on monophasic action potentials (MAP) recorded from the myocardial surface by means of contact electrode were studied in 30 open-chest rabbits. The MAPA was increased and MAPD50, MAPD90 were prolonged with PNS (100, 200 mg.kg-1, iv), while the Vmax remained unchanged. PNS (300-1200 micrograms.ml-1) inhibited the automaticity of isolated guinea pig right atria and the contractility of the left atria. The positive inotropic action of ouabain (0.2 mumol.L-1) on isolated guinea pig left atria was decreased in the presence of PNS 300 micrograms.ml-1.

[Pharmacological studies on the comparison between the drainage and certified Fel Ursi]

A comparison between the drainage and certified Fel Ursi was studied by pharmacological methods. The results demonstrated that the drainage Fel Ursi was similar to the certified products in anti-inflammatory, antipyretic, sedative, anticonvulsive, antispasmodic and bacteriostatic actions.

Sindbis virus: an efficient, broad host range vector for gene expression in animal cells

Sindbis virus, an enveloped virus with a single-stranded RNA genome, was engineered to express a bacterial protein, chloramphenicol acetyltransferase (CAT), in cultured insect, avian, and mammalian cells. The vectors were self-replicating and gene expression was efficient and rapid; up to 10(8) CAT polypeptides were produced per infected cell in 16 to 20 hours. CAT expression could be made temperature-sensitive by means of a derivative that incorporated a temperature-sensitive mutation in viral RNA synthesis. Vector genomic RNAs were packaged into infectious particles when Sindbis helper virus was used to supply virion structural proteins. The vector RNAs were stable to at least seven cycles of infection. The expression of CAT increased about 10(3)-fold, despite a 10(15)-fold dilution during the passaging. Sindbis virus vectors should prove useful for expressing large quantities of gene products in a variety of animal cells.

Expression of a putative plant viral gene in Escherichia coli

A recombinant plasmid, pCB300, was constructed which carries a cauliflower mosaic virus (CaMV) DNA insert corresponding to nucleotides 1825-2280, including the coding sequence (1830-2219) of open reading frame III (ORF III). This CaMV DNA insert was fused with the amino-terminal portion of the beta-galactosidase gene. Transcription of the hybrid gene is controlled by the lac promoter, which is repressed in Escherichia coli strain JM103 and can be induced by isopropylthio-beta-D-galactoside (IPTG). When the promoter is derepressed, cells harboring the chimeric plasmid produce an Mr 16 000 fusion protein. This protein is immunodetected by antibodies raised against an amino terminal synthetic peptide of 19 amino acids corresponding to a sequence predicted from the nucleotide sequence of ORF III.

A second cauliflower mosaic virus gene product influences the structure of the viral inclusion body

We have used electron microscopy of thin sections and experiments on isolated viroplasms to compare the properties of four strains of cauliflower mosaic virus (CaMV), three of which were partially or completely deleted in open reading frame (ORF) II. Our results confirm that this gene is required for aphid transmissibility and show that the product of ORF II influences the firmness with which virions are held within the viroplasm. Analysis of the proteins in the viroplasms showed that a mutant with a partial deletion in ORF II produced a protein smaller than the normal ORF product. This smaller protein was non-functional with respect both to aphid transmissibility and properties of the viroplasms.

Identification by immunoprecipitation of cauliflower mosaic virus in vitro major translation product with a specific serum against viroplasm protein

A highly specific antiserum was prepared against purified cauliflower mosaic virus viroplasm-protein (VmP). A virus specific in vitro major translation product (TPmaj), encoded by the 19S poly(A) RNA fraction from cauliflower mosaic virus infected turnip leaves, was recognized by this antiserum. The N-terminal sequence of TPmaj corresponds to the sequence following the first in-phase initiation codon in gene VI of the cauliflower mosaic virus genome. Both VmP and TPmaj have blocked termini and probably start from the same AUG codon.