Human parathyroid adenomas are aberrantly regulated by extracellular calcium. We tested pertussis toxin, which ADP-ribosylates and inactivates several guanine nucleotide regulatory proteins, to test the role of these proteins in the secretory control of adenomatous parathyroid tissue. Pertussis toxin did not affect basal cAMP accumulation in 12 adenomas and enhanced parathyroid hormone (PTH) release in 6 of 10 adenomas. Prostaglandin F2 alpha (PGF2 alpha) inhibited cAMP in three of six adenomas, and pertussis toxin pretreatment did not affect this result. PTH release in 7 of 10 adenomas was inhibited by PGF2 alpha, and pertussis toxin did not significantly alter PTH release. Pertussis toxin catalyzed ADP-ribosylation of a 40-kDa protein in all adenomas tested (n = 8). We conclude that cAMP accumulation was not affected by pertussis toxin but that in 6 of 10 adenomas, the toxin enhanced PTH release. We suggest that cAMP accumulation and PTH release may be uncoupled from negative control by inhibitory ligands in adenomatous tissue or that the G-proteins involved do not couple to regulatory receptors or to effector.

Adenoma↗

PubMed1988

Veratridine-induced high-frequency asynchronous release of inhibitory transmitter quanta in crayfish nerve-muscle synapses superfused with normal and low-calcium saline.

Crayfish fibres of opener muscles were voltage clamped to E = -80 mV membrane potential (T = 19-22 degrees C), and veratridine (10-100 mumol/l) was added to the superfusate. Within 30-60 s this caused large fluctuations of the clamp current due to vigorous asynchronous quantal release from the inhibitory nerve terminals along the muscle fibre. Excitatory postsynaptic receptors were previously desensitized by application of 5 mmol/l glutamate. Current fluctuations were evaluated by means of the noise analysis technique. Typically, 100 mumol/l veratridine increased instantaneously the quantal release rate n from n less than 1 quantum/s to n congruent to 10,000 quanta/s. Thereafter, n declined exponentially with a time constant of congruent to 70 s. On average, about 500,000 inhibitory quanta could be liberated in this way from the terminals on a single muscle fibre of congruent to 1 mm length. Serotonin (1 mumol/l) facilitated the effect of lower veratridine concentrations (1-10 mumol/l). In opener muscles veratridine-induced asynchronous quantal release showed little dependence on the bath concentration of Ca2+. The opposite was found for fibres of the superficial abdominal extensor muscle. Beside postsynaptic current fluctuations, veratridine elicited slowly changing average postsynaptic DC-currents which could be explained partly by superposition of individual inhibitory quantal currents. These DC-currents suggest that beside inhibitory quantal release another factor activates inhibitory postsynaptic receptors after application of veratridine.

Animals↗

PubMed1988

Effect of lithium on veratridine-induced quantal and non-quantal release from inhibitory nerve terminals in crayfish muscle.

Muscle fibres of small crayfish were voltage clamped and superfused for about 10 min with Li+ saline (Na+ replaced by Li+) which contained 5 mmol/l glutamate to desensitize excitatory postsynaptic receptors. Then 100 mumol/l veratridine were added to the superfusate which caused strong asynchronous quantal release of inhibitory transmitter. However, in the presence of Li+ strong inhibitory quantal release was only transient. It could be activated a second time by removal of Li+ and readministration of Na+. From the total of 0.7 to 1.1 million quanta released by veratridine only about 30-35% could be released in Li+ saline. The voltage clamp DC-currents recorded during veratridine-induced quantal release suggested that a non-quantal release component is additionally involved. This non-quantal release component was most prominent during the period of quantal release in Li+ superfusate while it was less obvious during the second enhancement of quantal release in normal saline. Together with previous results (Martin and Finger 1988) it may be concluded that quantal release, but not non-quantal release, is decreased by Li+ in the nerve terminals.

Animals↗

PubMed1988

Quantification of the glycolytic origin of plasma glycerol: implications for the use of the rate of appearance of plasma glycerol as an index of lipolysis in vivo.

To assess whether plasma glycerol could be directly derived from plasma glucose, nine postabsorptive dogs were infused with [U-14C] glucose and [2-3H] glycerol to measure the rates of appearance of plasma glucose and glycerol and the conversion of plasma glucose to glycerol before (basal) and after two hours of infusion of glucose (45 mumol/kg/min). Basally (plasma glucose 4.9 +/- 0.2 mmol/L; plasma insulin 5.9 +/- 0.2 microU/mL), rates of appearance of plasma glucose and glycerol were 20 +/- 2 and 5.9 +/- 1.3 mumol/kg/min, respectively, and 1.6 +/- 0.6% of plasma glycerol was derived from plasma glucose. After glucose infusion (plasma glucose 9.1 +/- 0.7 mmol/L; plasma insulin 21.1 +/- 1.9 microU/mL), the rate of appearance of plasma glycerol decreased 80% to 1.1 +/- 0.3 mumol/kg/min and the percent of plasma glycerol from glucose increased significantly to 6.9 +/- 2.9. However, the absolute rate of conversion of glucose to glycerol did not change (0.09 +/- 0.03 v 0.07 +/- 0.03 mumol/kg/min). We conclude that even under conditions of stimulated glycolysis and inhibited lipolysis, only a small amount of plasma glycerol is derived from plasma glucose. Thus, rates of appearance of plasma glycerol can be used as a measure of rates of overall lipolysis in vivo.

Animals↗

PubMed1988

Facial asymmetry while posing positive and negative emotions: support for the right hemisphere hypothesis.

The purpose of this report was to examine facial asymmetry during the expression of positive and negative emotions. In addition, methodological factors in the study of facial asymmetry were considered. Subjects were 16 neurologically-healthy right-handed adult males, videotaped while posing eight facial expressions (positive and negative) under two conditions (verbal command and visual imitation). Separate asymmetry ratings of the two sides of the face were made by judges viewing normal or mirror-reversed versions of the videotape. There were no effects of valence, condition, or videotape orientation on the asymmetry ratings, and, in general, expressions were produced significantly more intensely on the left than the right side of the face. This finding is consistent with the hypothesis that the right cerebral hemisphere is dominant for the expression of facial emotion of both valences.

Dominance, Cerebral↗

PubMed1988

Factors that affect transposition mediated by the Tn21 transposase.

The frequencies of one-ended transposition mediated by the Tn21 transposase acting on plasmids containing 38-bp inverted repeat sequences (IRs) of both Tn21 and of Tn501/Tn1721 and Tn2501 were measured. The enzyme acted on all these IRs, but more efficiently on the homologous sequences. These differences were magnified when the enzyme acted on plasmids containing two copies of the IRs, inverted with respect to each other. The Tn21 enzyme did not recognize the IR of Tn3. The Tn501 transposase did not mediate measurable one-ended transposition of any of the plasmids used, including those containing an IR of Tn501.

DNA Transposable Elements↗

PubMed1988

[Comparative study of sodium valproate and ketoprofen in the treatment of postoperative pain].

Experimental data has shown that sodium valproate has analgesic properties in animals, probably by way of the increase in cerebral and spinal gamma amino-butyric acid (GABA) it induces. A study was therefore designed to assess this analgesia in man in the postoperative period. A first open study was carried out on 12 consenting patients, who were each given 15 mg.kg-1 sodium valproate intravenously over 20 min. A significant decrease in pain intensity, measured by an analogic visual scale, was seen from the 20th min up to the 140th min. A controlled double-blind study was then carried out; it included three groups of 13 patients each. Patients in group 1 were given placebo (5% dextrose); group 2 patients were given 15 mg.kg-1 sodium valproate intravenously over 20 min, and group 3 patients 2 mg.kg-1 ketoprofen intravenously over 20 min also. There was no difference in the pain intensity profile of groups 1 and 2: sodium valproate was no more efficient than placebo in relieving postoperative pain. However, ketoprofen gave a prompt and effective analgesic effect. The clinical data obtained with sodium valproate in man during the postoperative period stand in contrast with the promising animal results. Sodium valproate cannot be recommended for the treatment of postoperative pain.

Adult↗

PubMed1988

Evaluation of an apparatus designed for the collection of sidestream tobacco smoke.

Explore the source record for details and available documents.

Chemical Phenomena↗

PubMed1988

Pefloxacin in the treatment of nosocomial lower respiratory tract infections in intensive care patients.

Pefloxacin was used to treat nosocomial pulmonary infections in 46 mechanically ventilated patients. All patients had one or more underlying diseases and were given pefloxacin at a dose of 800 mg or 1200 mg daily in two or three divided doses. The commonest bacterial isolates were Staphylococcus aureus, Pseudomonas aeruginosa and enterobacteria. Of these patients, 33 (72%) showed a favourable response, one patient relapsed and 12 (26%) were considered failures. Superinfections occurred in 10 (22%). Of the 62 isolated potential pathogens, 53 (85%) were completely eradicated. Side effects were mild and treatment was withdrawn in only three patients. Pefloxacin can be considered as a possible therapeutic agent for the treatment of nosocomial pulmonary infections.

Adolescent↗

PubMed1988

Tobramycin dosing in mechanically ventilated patients. Inaccuracy of a 'rule of thumb'.

The ability of a simple rule of thumb, based on creatinine clearance, to predict tobramycin serum concentrations was evaluated in mechanically ventilated patients. They were given tobramycin intravenously over 30 min at 8 h intervals. Creatinine clearance was estimated from the formula developed by Cockcroft & Gault (1976, Nephron 16, 31-41) or was calculated after urine collection for 24 h. The loading dose was 1.5 mg/kg and then dose adjustments were performed on a daily basis. Patients were studied on day 1 and day 3. Mean values of peak and trough levels were within the therapeutic range, but individual values were outside the therapeutic range in 30% to 70% of patients on both day 1 and day 3, most of the patients having subtherapeutic serum concentrations. This was mainly related to the high volume of distribution of tobramycin calculated in these patients. These results further emphasize the need to monitor serum concentrations and to use an individual pharmacokinetic method to make dose adjustment.

Adult↗

PubMed1988

Pseudomonas aeruginosa diaminopimelate decarboxylase: evolutionary relationship with other amino acid decarboxylases.

The lysA gene encodes meso-diaminopimelate (DAP) decarboxylase (E.C.4.1.1.20), the last enzyme of the lysine biosynthetic pathway in bacteria. We have determined the nucleotide sequence of the lysA gene from Pseudomonas aeruginosa. Comparison of the deduced amino acid sequence of the lysA gene product revealed extensive similarity with the sequences of the functionally equivalent enzymes from Escherichia coli and Corynebacterium glutamicum. Even though both P. aeruginosa and E. coli are Gram-negative bacteria, sequence comparisons indicate a greater similarity between enzymes of P. aeruginosa and the Gram-positive bacterium C. glutamicum than between those of P. aeruginosa and E. coli enzymes. Comparison of DAP decarboxylase with protein sequences present in data bases revealed that bacterial DAP decarboxylases are homologous to mouse (Mus musculus) ornithine decarboxylase (E.C.4.1.1.17), the key enzyme in polyamine biosynthesis in mammals. On the other hand, no similarity was detected between DAP decarboxylases and other bacterial amino acid decarboxylases.

Amino Acid Sequence↗

PubMed1988

Decompression and circumferential stabilization of unstable spinal fractures.

A technique of anterior decompression of the spinal canal with anterior strut grafts, followed by posterior instrumentation and local fusion, is described in a group of 18 patients with unstable thoracolumbar fractures. All patients were found to have greater than 50% encroachment of the spinal canal and a preoperative kyphosis of 21.8 degrees. At follow-up 81% of patients with incomplete neurological lesions improved at least one Frankel Grade. Residual encroachment on the spinal canal was 4.6% and at follow-up the kyphotic angle was 17.1 degrees. Complications included one anterior graft loosening (not requiring revision), three loosened rods, only one of which required revision, and one fractured Harrington rod which did not require revision. The authors conclude that this technique is an effective and safe method for treating unstable thoracolumbar injuries and is recommended if anterior instrumentation is unavailable.

Adult↗

PubMed1988

Effect of Hormone Treatment on Growth Bud Formation and Free Amine and Hydroxycinnamoyl Putrescine Levels in Leaf Explant of Nicotiana tabacum Cultivated in Vitro.

Foliar explants of Nicotiana tabacum cv Xanthi n.c. were cultured on four different media: a basal medium, basal medium plus benzyladenine, basal medium plus 2,4-dichlorophenoxyacetic acid (2,4-D), and the basal medium containing both hormones. No differentiation or cell division occurred in leaf explants cultured on the basal medium. Addition of benzyladenine caused the formation of buds on the explants, while 2,4-D caused callus formation and proliferation. Likewise, only callus was formed when explants were cultured on medium containing both hormones, but growth was significantly greater than that of callus grown on a medium containing 2,4-D alone. The levels of amines and hydroxycinnamoyl putrescines were determined in the four types of explants. In nongrowing explants, amines (except an aromatic amine, tyramine) and hydroxycinnamoyl putrescines were always at a low level and only small changes in their concentrations were observed. In callus cultures, amine (except an aromatic amine, phenethylamine) and hydroxycinnamoyl putrescine levels were higher than those found in bud cultures. In all the media, transitory accumulation of aromatic amines occurred after a few days of culture. Higher levels of hydroxycinnamoyl putrescines were attained in callus cultures with a slow growth rate (2,4-D alone) than in callus cultures with a fast growth rate (benzyladenine + 2,4-D). The formation of buds was accompanied by significant changes in putrescine and hydroxycinnamoyl putrescine levels. Increasing levels were found during the first 14 days in culture when cell multiplication was rapid, followed by a sharp decline after 20 days in culture as the rate of cell division decreased and differentiation took place. The relationship among amines, hydroxycinnamoyl putrescines, and cell division and bud formation is discussed.

Journal Article↗