[Results of heterologous tracheal transplants in animal experiments (author's transl)]

In the present study, 7 x 15 mm Cialit-preserved human tracheal segments were grafted to the tracheas of five 3-month old piglets. 72-120 days later, the animals were sacrificed and the grafts with proximal and distal control areas were removed. Tissues were then examined macroscopically and by light and scanning electron microscopy. We found that: (1) all grafts had taken well; (2) no animal suffered from clinical signs of respiratory obstruction or inflammation; (3) although luminal diameters of the tracheas increased from 8 mm to 22 mm, the size of the grafts remained unchanged but the resulting tracheal stenosis did not cause respiratory obstruction; (4) the graftet areas showed re-epithelialization. The nature of the re-epithelialization as well as the fate of the submucosa and tracheal cartilage will be reported in a subsequent publication.

Effect of pyridoxine on plasma levels of HGH, PRL, and TSH in normal women

The effect of chronic administration of pyridoxine (vitamin B6) on HGH, basal and TRH stimulated PRL and TSH levels was studied in seven healthy female volunteers. HGH and TSH basal levels remained unaffected. Basal PRL and TRH stimulated PRL and TSH levels were slightly reduced without statistical significance (P greater than 0.05). The results indicate, that stimulation of the hypothalamic dopaminergic pathway by pyridoxine is highly variable and unpredictable. Therefore it seems meaningless to recommend vitamin B6 for the treatment of hyperprolactinaemia.

Purification and properties of spinach leaf cytoplasmic fructose-1,6-bisphosphatase

Cytoplasmic fructose-1,6-bisphosphatase has been purified from spinach leaves to apparent homogeneity. The enzyme is a tetramer of molecular weight about 130,000. At pH 7.5, the Km for fructose 1.6-bisphosphate was 2.5 micron, and for MgCl2 0.13 mM; the enzyme was specific for fructose 1,6-bisphosphate. Saturation with Mg2+ was achieved with lower concentrations at pH 8 than at pH 7. AMP and high concentrations of fructose 1,6-bisphosphate inhibited enzyme activity. Ammonium sulfate relieved the latter inhibition but was itself inhibitory when substrate concentrations were low. Acetylation studies demonstrated that the AMP regulatory site was distinct from the catalytic site. Cytoplasmic fructose-1,6-bisphosphatase may contribute to the regulation of sucrose biosynthesis in plant leaves.

[Acute solitary gastric erosion (Dieulafoy) (author's transl)]

Acute solitary gastric erosion (Dieulafoy) is one rare cause of fulminant, fatal acute gastric haemorrhage. Conservative treatment is usually lethal and elimination of the source of haemorrhage by active surgical intervention is the only possible form of therapy. The key to successful surgical treatment is early preoperative diagnosis by means of emergency gastroscopy.

Antagonism of morphine with naloxone in dogs: cardiovascular effects with special reference to the coronary circulation

The cardiovascular effects of naloxone 15 microgram/kg following morphine 2.0 mg/kg were studied in closed-chest dogs during light nitrous oxide-halothane anaesthesia. The bolus injection of naloxone caused an increase in heart rate (73%), cardiac output (20%) and mean arterial pressure (20%). Total peripheral resistance was unaffected. LV dP/dt max and LV dP/dt max/IP increased by 25% and 14% respectively, but positive inotropic effects could not be shown when load data, heart rate and the decrease in left ventricular ejection fraction (22%) were taken into consideration. The cardiovascular stimulation resulted in an increase in myocardial oxygen demand (66%) which was met by an increase in coronary blood flow (59%). The data suggest that the antagonism of narcotics with high doses of naloxone may impair the myocardial oxygen supply in patients suffering from coronary insufficiency. It is concluded that naloxone should be titrated for each patient to ensure adequate reversal of respiratory depression and to avoid circulatory stress.

[Effect of high dosages of morphine and meperidine on haemodynamics, coronary blood flow and myocardial oxygen consumption in comparison to fentanyl and piritramide (author's transl)]

Although morphine is one of the oldest drugs known to man, it has only recently been used in large doses as an anesthetic agent. The main advantage is the cardiovascular stability. The purpose of this investigation was to study the circulatory response to high equianalgesic doses of morphine and meperidine. In 10 closed chest dogs during normoventilation and light background-anaesthesia (0.5 Vol. % halthane; N2O:O2 = 2:1) 2.0 mg/kg morphine and 15.0 mg/kg meperidine were given at random. Morphine produced a decrease in mean arterial blood pressure by 28%, which was paralleled by an identical fall in total peripheral resistance. No negative inotropic effects were found. In contrast to this, the severe hypotension developing with meperidine (decrease in blood pressure by 54%) was the result of peripheral vasodilatation (46%) and of myocardial depression indicated by a sharp drop in dp/dtmax (59%), dp/dtmax/IP (14%) and in left ventricular ejection fraction (33%). Utilizing the thermodilution technique, the cardiac output remained largely unaffected with both narcotic analgesics, as the increase in heart rate (morphine 27%; meperidine 101%) compensated for the fall in stroke volume (morphine 19%; meperidine 55%). In spite of the altered haemodynamics there was no change in the myocardial energy demand, which was adequately met by the coronary blood flow measured with the pressure-difference technique. Both, morphine and meperidine, produced initially an increase in coronary blood flow and coronary venous oxygen saturation indicating coronary vasodilation. While the mechanism for the change in cardiovascular status with high doses of morphine is vasodilatation probably due to histamine release, the results of this study suggest a peripheral as well as a central (myocardial depression) site of action with meperidine. The results obtained from this study were compared with the data from a previous investigation on equianalgesic doses of fentanyl and piritramide and their clinical implications were discussed.

[The cardiovascular effects of the inspiratory N2O-concentration during piritramide anaesthesia in the dog (author's transl)]

Administration of nitrous oxide following large doses of narcotics has been reported to impair myocardial performance. In this investigation the effect of the inspiratory N2O-concentration (F1N2O = 0.0; 0.2; 0.4; 0.6; 0.8) upon haemodynamics, inotropism of the heart, coronary blood flow and myocardial oxygen consumption was studied in 8 dogs, which were normoventilated and narcotized with piritramide infused continuously (2.5 mg/kg-h). While 40% N2O(F1N2O = 0.4) decreased cardiac index (18%) and mean arterial pressure (5%) and increased total peripheral resistance (11%) significantly, the remaining inspiratory N2O-concentrations did not affect these parameters considerably. Load data, heart rate and the continuous decrease of LVdp/dtmax from 3170 mm Hg/s (F1N2O - 0.0) to 2175 mm Hg/s (F1N2O = 0.8) indicated negative inotropic properties of high concentrations of nitrous oxide. The myocardial oxygen demand, which was adequately met by the coronary blood flow, decreased with increasing N2O-concentrations initially by 18% (F1N2O = 0.4) due to bradycardia, slight hypotension and reduction in inotropism. Inhalation of 80% N2O, however, returned the energy demand of the heart to control levels (F1N2O = 0.0) resulting from increased myocardial wall-tension (increase in left ventricular end-diastolic pressure by 30%). The efficiency of left ventricular external work decreased from 18.6% (F1N2O = 0.0) to 14.7% (F1N2O - 0.8) indicating that myocardial performance was uneconomically influenced by high inspiratory N2O-concentrations and large doses of narcotics. The clinical implications of the results were discussed.

Efficient purification and molecular properties of spinach chloroplast fructose 1,6-bisphosphatase

A relatively straightforward procedure has been developed for the purification of chloroplast fructose bisphosphatase from spinach leaves to apparent homogeneity and with 80% yield. The molecular weight of the enzyme was about 160 000. Chloroplast fructosebisphosphatase consists of four possibly identical subunits and, at pH 8.8, EASILY DISSOCIATES INTO EQUAL HALVES WITH LOWered activity. Sigmoid saturation curves with Hill coefficients between 3.0 and 3.7 were obtained for fructose 1,6-bisphosphate and Mg2+. Incubation of the enzyme with 20 mM dithiothreitol slowly altered the response to pH from no activity measured at pH 7.5 and full activity at pH 8.8 to equal activity at each of these pH values; at the same time the number of freely available sulphydryl groups increased from four to twelve per molecule. These properties are considered in the context of the observed activation of this enzyme following illumination of chloroplasts.

[Combined radiomanometric and histological studies in the surgery of Vater's ampulla]

In 34 patients a transduodenal sphincteroplasty was performed for benign stenosis of the papilla of Vater or stones in the area of the papilla. The combined intraoperative radiomanometric investigations as well as the histological examinations of intraoperative biopsis of the liver and the papilla of Vater suggest that in most cases with elevated pressure values of the common duct pathological changes of the liver with signs of cholostasis as well as of the papilla of Vater either with pathohistological alterations or with stones in this area can be detected. Constantly, histological changes of the papilla of Vater lead to pathologically elevated pressures in the common duct. In these cases transduodenal sphincteroplasty is recommended instead of only treating with a bougie or dilating the papilla. The indication for this procedure can be objectified by intraoperative radiomanometry.

Self-association of human erythrocyte phosphofructokinase. Kinetic behaviour in dependence on enzyme concentration and mode of association

The kinetic behaviour of human erythrocyte phosphofructokinase has been analyzed over a relative wide range of enzyme concentration (0.01 -- 1.7 mug/ml). The kinetic cooperativity which becomes apparent when the enzymic reaction rate is plotted versus the fructose 6-phosphate concentration decreases with increasing enzyme concentration. Simultaneously, a decrease of the half-saturation concentration for fructose 6-phosphate [S]0.5 is observed. Maximum velocity passes through a maximum at increasing enzyme concentrations. Sets of curves representing specific enzymic activity of phosphofructokinase versus enzyme concentration obtained at various fixed concentrations of fructose 6-phosphate and ATP are analyzed. The shapes of these curves are interpreted in terms of an association model of human erythrocyte phosphofructokinase, in which an inactive dimer (Mr 190000) and active multimers of the dimeric form are involved. The conclusion is drawn that the sigmoidal shape of the plots of the enzymic reaction rate versus fructose 6-phosphate concentration is partially caused by a displacement of the equilibrium between different states of association of phosphofructokinase to multimers by this substrate. On the other hand, the inhibition of the enzyme by high concentrations of ATP may be partially caused by a shift of this equilibrium to the state of the inactive dimer.

[Pyrogen testing in vitro using the Limulus test]

The applicability of the Limulus test for the pyrogen test was checked in comparison to the pyrogen test in rabbits. In 6 out of 24 lots of raw materials and drugs pyrogens could be detected by means of the pyrogen test in rabbits. 2 of these 6 lots showed positive reaction in the Limulus test, there were no false positive results. Testing 7 bacterial strains in modified quantity of germs the Limulus test turned out to be more sensitive than the pyrogen test in rabbits. The application of this in vitro test as a complement to the pyrogen test in rabbits for a certain kind of problems is discussed.