Myocardial hemodynamics during induced hypotension: a comparison between sodium nitroprusside and adenosine triphosphate

Adenosine triphosphate (ATP) has been reported to be a hypotensive agent similar in effect to sodium nitroprusside (SNP). The purpose of this study was to examine and compare the effects of both SNP and ATP on general coronary hemodynamics, myocardial O2 consumption, and circulating catecholamines. Twelve dogs were anesthetized with 1.0% halothane and given either SNP or ATP by controlled infusion to reduce their systemic blood pressure by 50% for a 2-h period followed by a (blood pressure) recovery period. The ATP-induced hypotension was rapid, easily controlled, not accompanied by tachyphylaxis over the 120 min studied, and resulted in an increase in coronary sinus blood flow (CSBF), which plateaued at 260% above control. The increase in CSBF was almost immediate and remained at this elevated level for the duration of the induced hypotension. During the ATP-induced hypotension, there was no change in heart rate or circulating catecholamines. A 60% reduction in myocardial O2 uptake was observed, presumably from the cardiac unloading. In contrast, SNP-induced hypotension required a marked increase in dose over time, did not significantly increase CSBF, did increase heart rate, and resulted in large increases in circulating plasma catecholamines. Neither agent affected cardiac output. ATP-induced hypotension resulted in no change in cardiac lactic acid uptake, while SNP caused lactic acid production, indicating possible cardiac ischemia or cyanide toxicity.

Physical and genetic mapping of safflower chloroplast DNA : Location of psbA, rbcL, atpA and rrnA

A physical map of safflower (Carthamus tinctorius L.) chloroplast DNA has been generated using SalI, PstI, KpnI and HindIII restriction endonucleases. The circular plastid genome (151 kbp) has the usual inverted repeat. Heterologous probes containing psbA, rbcL, atpA or rrnA structural genes mapped colinearly with spinach and other chloroplast genomes.

The chloroplast genome of Carthamus tinctorius

A physical map of safflower (Carthamus tinctorius L.) chloroplast DNA has been generated using SalI, PstI, KpnI and HindIII restriction endonucleases. Southern blots to single and double digests by these enzymes were hybridized with 32P-dCTP nick-translated KpnI probes, which were individually isolated from agarose gels. The plastid genome was found to be circular (151 kbp), to contain a repeated sequence of about 25 kbp, and to have small and large single copy regions of approximately 20 and 81 kbp, respectively. Heterologous probes from spinach and Euglena containing psbA, rbcL, atpA or rrnA structural genes were also hybridized with such single and double restriction enzyme digests and mapped on this circular chloroplast genome. The genetic map was found to be co-linear with that of spinach and many other higher plants.

Construction and mapping of safflower chloroplast DNA recombinants and location of selected gene markers

DNA was isolated and purified from chloroplasts of safflower (Carthamus tinctorius L.), digested with HindIII restriction endonuclease, and ligated into the HindIII site of the plasmid pUC9. Recombinant DNAs were isolated from ampicillin resistant white colonies which grew in the presence of the appropriate indicator, digested with HindIII, and then identified by comparison of agarose gel electrophoretic mobilities. HindIII digests of chloroplast DNA were used as a standard. Such recombinants were radiolabeled and hybridized with Southern blots of PstI, SalI, KpnI, and HindIII single and double digests of safflower chloroplast DNA. A physical map was subsequently generated showing the location of each recombinant on the circular plastid genome. Recombinants containing heterologous chloroplast gene markers from spinach or Euglena were also radiolabeled and mapped. The relative mapping positions of these genes are in good agreement with those which have previously been published for spinach and several other higher plants.

Restriction endonuclease cleavage site map of safflower (Carthamus tinctorius L.) chloroplast DNA

The restriction endonucleases SalI, PstI, KpnI and HindIII have been used to construct a physical map of safflower (Carthamus tinctorius L.) chloroplast DNA. This was accomplished by hybridizing Southern blots of single and double digested chloroplast DNA with (32)P-dCTP nick-translated SalI, KpnI and HindIII probes which were individually isolated from agarose gels. The chloroplast DNA was found to be circular and to contain approximately 151 kbp. In common with many other higher plant chloroplast DNAs a sequence of about 25 kbp is repeated in an inverted orientation. The small and large single copy regions separating the two repeated segments contain about 20 kbp and 81 kbp, respectively. The rRNA structural genes were also mapped by Southern blot hybridization and are co-linear with several other plant species.

Effects of verapamil on uterine blood flow and maternal cardiovascular function in the awake pregnant ewe

Calcium entry blocking drugs may have a role in the treatment of maternal and fetal tachyarrhythmias, as well as for treatment of premature labor. This study was undertaken to assess the hemodynamic effects of verapamil in the awake pregnant ewe. Verapamil, 0.2 mg/kg administered intravenously over 3 min, resulted in the following maternal cardiovascular changes: transient (2 min) but significant decreases in systolic, diastolic, and mean blood pressures, and significant but equally transient increases in central venous pressure and mean pulmonary arterial pressure. Pulmonary capillary wedge pressure increased for 5 min. These results are consistent with the negative inotropic and peripheral vasodilating effects of verapamil. Cardiac output, systemic vascular resistance, and pulmonary vascular resistance were unaffected. Uterine blood flow decreased 25% at 2 min and remained significantly (7-18%) below control levels for 30 min after drug injection. The effects of verapamil on uterine blood flow suggest that it should be used with caution in cases where uteroplacental perfusion is compromised.

Isolation and characterization of safflower (Carthamus tinctorius L.) chloroplast DNA

Safflower (Carthamus tinctorius L.) chloroplasts were isolated and purified with the aid of commercially available nylon mesh, differential centrifugation, and DNase I treatment. These chloroplasts were free of nuclei as determined by light microscopy of aceto orcein stained preparations, and similar to those observed by electron microscopy in spinach and many other higher plants, being bounded by a double membrane layer and characterized by the presence of a lamellar system surrounded by embedding matrix, and stacked membranes or grana lamallae. DNA was isolated and purified from such chloroplasts, and characterized with respect to cesium chloride density gradient isopycnic centrifugation, denaturation, renaturation kinetics and restriction enzyme analysis. These studies show that safflower chloroplast DNA is similar to many other higher plant DNAs having a density of 1.700 g/cm3 (G + C = 40.8%), a Tm of 86 degrees C (G + C = 40.7%) and a molecular complexity and genome size of about 10(8) daltons.

Adverse behavioral effects of the anticholinesterase poisoning protector pralidoxime methanesulfonate

Pralidoxime methanesulfonate (P2S) has anticholinesterase protective properties, but it also has an array of gastrointestinal (GI) symptoms. Because such a symptom would be disadvantageous to occupational workers who handled and used organophosphorus anticholinesterase continuously, and to soldiers who have had oral pretreatment in a situation where anticholinesterase agent poisoning is a possibility, this question was investigated in rats using three behavioral paradigms to evaluate the feasibility of the oral prophylactic regimen. These are: (1) conditioned taste aversion (CTA), (2) operant behavior and (3) spontaneous locomotor activity (SMA); these three behavioral parameters are analogous to toxicant-induced gastrointestinal (GI) disturbances, performance of learned tasks and behavioral arousal, respectively. Dose-response studies of P2S in dose levels of 0.2, 0.4, 0.8 and 1.6 gm/kg (P.O.) were evaluated. The results consistently demonstrated that only the highest dose significantly produced marked decreases in consumption of flavored solution associated with its ingestion, suppressed keypress response maintained under a 20-response fixed-ratio schedule of water presentation, and inhibited SMA. By inference, if CTA, operant behavior and SMA are appropriate paradigms, P2S, on an acute single oral high dose level, would cause GI disturbances, impair task performance and induce sedation in man.

Empirical equation that can be used to determine genetic map distances from tetrad data

An empirical equation has been developed that can be used to calculate genetic map distances from tetrad data with good accuracy for distances of up to at least 120 centimorgans.

Quantitative structure-activity relationships and possible mechanisms of action of bispyridinium oximes as antidotes against pinacolyl methylphosphonofluoridate

The antidotal efficacy of bispyridinium oximes against the poisoning by pinacolyl methylphosphonofluoridate can be correlated well with their physicochemical parameters. Good correlation was observed between the efficacy of antagonism against pinacolyl methylphosphonofluoridate and antinicotinic action of these oximes. X-ray structural analysis showed that these oximes possessed structural similarity to nicotine and acetylcholine of nicotinic conformation. A new model of antidotal action, other than reactivation, against the poisoning by pinacolyl methylphosphonofluoridate was proposed for these bispyridinium oximes through nicotinic receptor binding. The antagonistic efficacy of these antidotes against pinacolyl methylphosphonofluoridate may be attributed to their direct antagonism at nicotinic receptor as well as reactivation of inhibited acetylcholinesterase.

Clinical and histological observations on the application of intermingled auto- and porcine-skin heterografts in third degree burns

Escharectomy and skin grafting with both homograft and porcine skin has become an effective method in treating massive third degree burns. Seventeen patients and 21 operations of intermingled transplantation of auto- and fresh porcine skin heterografts after escharectomy of the severe burn wounds have been carried out since March 1973. Clinical and histological data are summarized, among which we observed the 'fusing phenomena' of auto- and porcine skin heterografts in 6 patients. Vascularization, 'turning red', viability and rejection as well as ways to improve the results of the grafting method are discussed. No vascular communication between fresh porcine skin and the host wound has been observed during the early postoperative period. The cause of 'turning red' is a reddish transudation between the graft and the host wound seen through the thin porcine skin. Based on histological observations, porcine skin is viable after transplantation. With nutritional support apparently coming from the underlying plasma and tissue fluid. Eventually the process of rejection is similar to that of homograft Better results are found with porcine skin grafts 0.4-0.5 mm in thickness placed 0.5-0.75 cm apart. In order to avoid large sloughing wound surfaces less than 20 per cent area of porcine skin coverage is advisable.

Very-Long-Baseline Radio Interferometry: The Mark III System for Geodesy, Astrometry, and Aperture Synthesis

The Mark III very-long-baseline interferometry (VLBI) system allows recording and later processing of up to 112 megabits per second from each radio telescope of an interferometer array. For astrometric and geodetic measurements, signals from two radio-frequency bands (2.2 to 2.3 and 8.2 to 8.6 gigahertz) are sampled and recorded simultaneously at all antenna sites. From these dual-band recordings the relative group delays of signals arriving at each pair of sites can be corrected for the contributions due to the ionosphere. For many radio sources for which the signals are sufficiently intense, these group delays can be determined with uncertainties under 50 picoseconds. Relative positions of widely separated antennas and celestial coordinates of radio sources have been determined from such measurements with 1 standard deviation uncertainties of about 5 centimeters and 3 milliseconds of arc, respectively. Sample results are given for the lengths of baselines between three antennas in the United States and three in Europe as well as for the arc lengths between the positions of six extragalactic radio sources. There is no significant evidence of change in any of these quantities. For mapping the brightness distribution of such compact radio sources, signals of a given polarization, or of pairs of orthogonal polarizations, can be recorded in up to 28 contiguous bands each nearly 2 megahertz wide. The ability to record large bandwidths and to link together many large radio telescopes allows detection and study of compact sources with flux densities under 1 millijansky.