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Biomedical subjects

E Kirchner

Publications and source records attributed to E Kirchner.

At least 37 records · Page 2Linked to original sources

[2-Amino-oxazoles as potential H-bonding agents in virostatic research. 4. Pharmacokinetics and pharmacologic-toxicologic profile of 2-guanidino-4,5-dipropyloxazole hydrochloride].

Out of the group of 2-amino-oxazoles 1 was found to be the most potent antiviral compound. Following p.o. or s.c. administration to rats, the 14C-labeled 1 was quickly and completely absorbed. The TRA was eliminated mainly via the kidneys and the liver with half-lives between 32 and 42 h. The acute pharmacodynamic effects of 1 were decrease of blood pressure, bradycardia, and inhibition of both gastric emptying and acid secretion. On smooth muscles spasmolytic and alpha-anti-adrenergic actions were predominant. After single administration the following MTD's were determined: 30 (mouse), 20 (rat), 10 mg/kg i.v. (pig), and 500 (mouse, rat), greater than 100 mg/kg p.o. (pig), respectively. In a subchronic toxicity study in rats, oral doses of 1 between 15 and 240 mg/kg given daily for 4 weeks were tolerated without any severe alterations related to the drug.

Administration, Oral↗

[Determination of oxygen content: a comparison between the new Oxystat-Photometer and the Lex-O2-Con].

The Oxystat-photometer (Fa. Andos) is a new instrument for measuring of oxygen content and haemoglobin of blood. Using specific agents oxygen and haemoglobin can be registered in small cuvettes. The principle of measurement is photometry. Additionally O2-saturation can be calculated. In 139 experiments we checked the reliability of the Oxystat-photometer in comparison to the Lex-O2-Con (Lexington Instruments Corporation). High significance could be demonstrated (r = 0.96). There was a range from the control value below 5%. Following investigations using calculation, results could be confirmed.

Adult↗

[The effect of clonidine on the intrapulmonary right-to-left shunt in one-lung ventilation in the dog].

Many vasoactive drugs--vasoconstrictors as well as vasodilators--impair the efficiency of hypoxic pulmonary vasoconstriction (HPV) and may cause dangerous hypoxemia during one-lung ventilation (1-LV). The effect of clonidine, a widely used alpha 2-agonistic antihypertensive agent, on intrapulmonary right-to-left shunt (Qs/Qt) during 1-LV has not yet been studied. METHODS. Twenty anesthetized beagle dogs were instrumented with a 7F Swan-Ganz catheter and an arterial line. A left thoracotomy in the lateral position was performed and the left main bronchus was prepared for clamping. Intravenous clonidine (5 micrograms/kg) was administered to 10 dogs. Anesthesia was maintained with either thiopental and fentanyl or halothane (0.8 insp. vol%) and fentanyl. The ventilatory frequency (100% O2, tidal volume 150 ml/kg) was adjusted to obtain an end-expiratory CO2 of 4.5%. Each dog underwent the following experimental sequence: (1) baseline measurements with 2-LV; (2) 20 min 1-LV (left lung atelectasis was achieved by clamping the left main bronchus); and (3) 20 min 2-LV. After allowing 30 min for conversion from i.v. to halothane anesthesia or vice versa, the procedure was repeated (5 dogs in each group received first i.v. and 5 dogs first halothane anesthesia). RESULTS. Qs/Qt was slightly but not significantly higher under halothane anesthesia in both groups during 1-LV as well as 2-LV (Table 1). No differences existed between the halothane and i.v. groups with regard to arterial pO2 and cardiac index. In the control group (i.v. or halothane, n = 20) Qs/Qt increased during 1-LV from 10.8 +/- 2.8% (mean +/- S.D.) to 26.6 +/- 5.5%, and in the clonidine group (i.v. or halothane, n = 20) from 7.2 +/- 2.3% to 18.3 +/- 5.4%. These differences between the control and clonidine groups are significant (P less than 0.001) for 1-LV as well as 2-LV. Arterial pO2 during 1-LV was reduced less in the clonidine group (573 +/- 48 to 390 +/- 99 mmHg) than in the control group (550 +/- 44 to 323 +/- 94 mmHg) (P less than 0.05). During 1-LV no significant differences between the two groups could be detected with regard to pulmonary artery pressure, mixed-venous pO2, pCO2, and pH. Heart rate, cardiac index, and oxygen uptake were significantly lower and arteriovenous O2 difference was significantly greater in the clonidine group, indicating better control of sympathoadrenergic activity under clonidine. CONCLUSIONS. We conclude that pretreatment with clonidine improves HPV during 1-LV. This effect of clonidine is probably due to reduced sympathetic nervous system activity.

Anesthesia, Inhalation↗

[Propofol for induction and maintenance of anesthesia during heart surgery. Results of pharmacological studies in man].

Numerous reports have concluded that propofol is suitable for maintenance of anesthesia by continuous infusion. The aim of this study was to evaluate the use of propofol and fentanyl for coronary bypass surgery in patients with good left ventricular function. The effects of this anesthetic combination on quality of anesthesia, hemodynamic status, and endocrine and metabolic responses were assessed. Postoperative recovery and side effects were also noted. The effects were compared with those of a standard method using etomidate, midazolam, and fentanyl. METHODS. Twenty patients who presented for aortocoronary bypass surgery (NYHA class II-III) were randomly allocated to one of two groups: propofol-fentanyl (group A) or etomidate-midazolam-fentanyl (group B). In each patient the dosage of the drugs was adjusted to obtain the optimum responses during induction and maintenance. RESULTS. Propofol in combination with fentanyl diminished mean arterial pressure (-28.7%) and heart rate (-17.3%) when used for induction in patients with ischemic heart disease, even in low doses and with slow administration. In 5 of the 10 patients it was impossible to prevent a critical fall in coronary perfusion without active intervention. However, during maintenance anesthesia, stable circulatory parameters were obtained with both drug regimens. Clinical signs thought to reflect myocardial ischemia were not observed. In both groups reductions in basal and stimulated catecholamine secretion were demonstrated. Similarly, perioperative cortisol secretion was reduced with both techniques. Despite all the complicated metabolic inhibitory effects seen, preoperative hormonal levels were restored within 1 h of the end of anesthesia. The magnitude and duration of the metabolic changes were found to be related to the duration of surgery. There was no evidence of non-homogeneous tissue perfusion as assessed by increases in lactate concentration, cardiac ischemia, or liver dysfunction in any of the patients. There were no postoperative complications in either group, but the return of consciousness, adequate spontaneous ventilation, and psychomotor activity was more rapid in the propofol patients. CONCLUSION. In summary, it can be concluded that a propofol infusion technique positively enhances the recovery period after cardiac surgery and provides good control during anesthesia. However, the use of propofolfentanyl for induction of anesthesia in patients with limited coronary perfusion is not recommended because of its hypotensive effect.

Anesthesia, Intravenous↗

Anaesthetic problems in ex situ resection of the liver.

Ex-situ resection of the liver is a new surgical technique for treatment of liver tumours not amenable to conventional surgery. This paper describes the cardiovascular and metabolic changes that occurred in nine consecutive such patients. No severe haemodynamic or pulmonary complications occurred. Specific problems were encountered during the prolonged anhepatic period, which lasted an average of 5.96 (SD 1.46) hours. Significant metabolic and coagulation disorders occurred 2 to 3 hours after hepatectomy because of complete loss of hepatic function. The predominant findings during the anhepatic period were hypoglycaemia and severe metabolic acidosis, mainly from increased levels of lactic acid. Exogenous administration of dextrose 5% at an average rate of 188 ml/hour was necessary to maintain normoglycaemia, while correction of metabolic acidosis required 403 (SD 159.79) mmol of sodium bicarbonate, supplemented by hyperventilation. Tris-hydroxymethylaminomethane was used when sodium overload was thought to be a problem. There was a marked decrease of Factor V and fibrinogen, a moderate thrombocytopenia and fibrinolysis. The severity of these alterations was dependent on the duration of the anhepatic period and the primary function of the re-implanted liver.

Acidosis, Lactic↗

[Use of calcium carbonate (CaCO3) as phosphate binder in dialysis patients in long-term follow-up over 3 years].

In 26 dialysis patients (age 46 +/- 47.8 years, dialysis 20.1 +/- 57 months) calcium carbonate was introduced to phosphate reduction for 3 years. The use of CaCO3 (4.4-9 g/d) for 9 months did reduce the phosphate level from 2.51 to 1.51 mmol/l in 77% of the patients and increase the calcium from 2.23 to 2.47 mmol/l. The long-term use use up to 3 years did'nt reduce the phosphate level effectively (mean value 2.24 mmol/l). In 77% of the patients a progression and in 42% new calcifications could be observed. The percentage of patients with soft tissue calcification within the 3-year CaCO3 therapy was increased from 43% to 67%. Therefore, CaCO3 alone in unsuitable for long-term use as phosphate binder in dialysis patients.

Aluminum↗

[Ex situ surgery of the liver--anesthesiologic management].

In a 40-year old patient multiple liver tumours that were otherwise regarded as irresectable were removed in an ex situ operation--according to the authors' knowledge for the first time in a human. After protective perfusion with a hypothermic HTK solution hepatectomy was performed. After extirpation of the tumours ex situ, the residual liver was re-implanted. The total operation time was 13 h 50 min, the anhepatic period lasted for 6 h 9 min. During the anhepatic period a venous bypass shunted the blood from the a femoral and the portal vein to an axillary vein. Considerable blood loss was balanced by the transfusion of 26 units of banked blood. Severe disturbances of blood coagulation could be avoided by early substitution with fresh frozen plasma, platelets and fresh blood. The long anhepatic phase caused an acidosis that required the application of 330 mVal NaHCC3. In the discussion the necessity for an aggressive intraoperative monitoring of haemodynamic and laboratory parameters is emphasized.

Adult↗

[Stabilization of the cardiovascular system in organ donors].

Every intensive care patient is a potential organ donor. For preserving organs, an aggressive shock therapy and controlled volume adaptation using the alpha-blocker hydergine is necessary. Minimal therapy is not allowed until it is decided whether the patient will survive or will become an organ donor. A vasopressor therapy for normalisation of blood pressure must not be carried out. Renal function (30 ml per hour are sufficient) must be achieved by improving perfusion with alternating infusions of dextran or hydroxyethyl starch and Ringer solution. Dopamine should not be used. The application of hyperosmolar/hyperoncotic solution (250 ml 7.5% sodium chloride in 6% dextran 70) gives a new chance for rapid restoration of perfusion in all vascular districts. This solution will also be prized by those who until now believed a vasopressor was indispensable. The number of organ donors will increase according to the reduction of vasopressor therapy.

Blood Circulation↗

[Ex situ operation on the liver. A new possibility in liver surgery].

A method for an ex situ operation of the liver is presented with the example of such an operation in a 40-year-old patient. With this operation bilateral liver metastases of a leiomyosarcoma--which were otherwise regarded as irresectable--were resected. Function of the liver after reimplantation was good. Liver protection was performed by perfusion with cardioplegic HTK-solution (Bretschneider). The techniques of liver ex- and implantation are based on the methods of liver transplantation. Extracorporal femoro-porto-axillary bypass for decompression of the inferior caval vein and portal vein was used throughout the anhepatic period of 6 h. It is supposed that the method described here--which according to the authors' knowledge has been performed for the first time in a patient--will open up new perspectives for the surgery of malignant and occasionally of benign tumors, if necessary also for other surgical liver diseases. As an additional possibility, in situ protection of the liver with consecutive operation of the bloodless liver in situ is discussed. This procedure will correspond for the most part to the ex situ technique described here.

Adult↗

[Dynamics of amino acid and protein metabolism of laying hens after administration of 15N-labeled wheat protein. 6. 15N incorporation into the contents and tissue of segments of the gastrointestinal tract and into the pancreas].

12 colostomized laying hens received, together with a conventional feed ration, 15N labelled wheat with a 15N excess (15N') of 14.37 atom-% over 4 days. 3 animals each were butchered after 12 h, 36 h, 60 h and 108 h after the last 15N' application and, apart from various organs, the contents and the tissue of the gastro-intestinal tract of each hen was divided into 3 fractions. TCA precipitation was carried out with the contents and the tissue of the 3 fractions. Nitrogen and its atom-% 15N' were determined in the supernatant and the precipitate. The 15N' amount in the contents of the crop and the stomachs, the small and large intestines is still considerable 12 h after the last 15N wheat feeding and still clearly detectable 108 h after it. The TCA precipitable amounts of 14N and 15N' of the contents of crop and stomach and that of the small intestine agree well; they are 75% and 50% resp. of the total N. The amount of atom-% 15N' of the contents of the small and large intestines remains the same up to 36 h after the last 15N' application and is higher at the following measuring points in the contents of the large intestine. A close correlation could be ascertained between the atom-% 15N' in the contents and tissue of the small and large intestines. The TCA soluble N quotas of both 14N and 15N' in the pancreas are higher than 50%.

Amino Acids↗

[Dynamics of amino acid and protein metabolism of laying hens after the administration of 15N-labeled wheat protein. 8. 15N-labeling of nitrogen and 15N incorporation into the amino acids of the liver].

Over 4 days 12 colostomized laying hens received, together with the ration, 36 g wheat with 14.37 atom-% 15N excess (15N'), The basic amino acids were nearly equally labelled. Three animals each were butchered after 12 h, 36 h, 60 h, and 108 h after the last 15N' application. Emission spectrometric determination of 15N' in the liver and in the amino acids was carried out. In addition, atom-% 15N' was determined in the free amino acids and the peptides. The labelling in the liver 12 h after the last 15N' application amounted to 1.75 atom-% 15N' and decreased after 108 h to 0.81 atom-% 15N'. The average TCA precipitable 15N' quota in the total 15N' amounted to 81.4% and was nearly identical at all measuring times. The arginine 15N' amount in the liver was twice as high as that of lysine 15N'. In dependence on the period of time after the last 15N' application the decrease in the labelling of the free arginine is considerable in comparison to free lysine. At the first measuring time (12 h) it was 1.69 atom-% 15N' and at the last one (108 h) 0.57 atom-% 15N'. Based on the results of 15N' labelling of the peptides in the liver further, more detailed series of experiments for studies of the peptide metabolism in the liver should be carried out.

Amino Acids↗

[Dynamics of amino acid and protein metabolism of laying hens after the administration of 15N-labeled wheat protein. 1.Problems, research program and 15N-labeling of urine].

In a 6-day preliminary period with a pelleted ration 12 colostomized laying hybrids received 15N labelled wheat protein over 4 days. The labelling of the wheat was 14.37 atom-% 15N excess (15N'). During the 4-day application of 15N wheat protein each hen consumed 12.08 g nitrogen, 3.52 g lysine, 2.12 g histidine, 4.41 g arginine, of which were 540 mg 15N', 18.1 mg lysine 15N', 21.5 mg histidine 15N' and 47.9 mg arginine 15N'. Heavy nitrogen was determined in urine and its uric acid-N in the daily urine samples of the individual animals. The average daily urine N excretion was 54% of the total nitrogen consumed with the ration. The labelling of the urine N reached a plateau on the fourth day of the experiment with 3.2 atom-% 15N'. On an average of the total experiment the quota of heavy nitrogen of the uric acid in the total 15N' of the urine was 83.4% and that of uric acid nitrogen in the total urine nitrogen 80.8%.

Amino Acids↗

[Dynamics of amino acid and protein metabolism of laying hens after administration of 15N-labeled wheat protein. 5. Incorporation of 15N into the blood fraction and its amino acids].

12 colostomized laying hens which received 15N labelled wheat over 4 days were butchered 12 h, 36 h, 60 h and 108 h (3 animals each) after the last 15N application. The intake of 15N excess (15N') from the wheat amounted to 540 mg 15N' during the application period. The 15N' in the blood plasma decreased after the last 15N' application from 0.76 atom-% to 0.55 atom-% after 108 h, the labelling of the corpuscular components at the same measuring points increased from 0.28 to 0.50 atom-% 15N'. 96.6% of the plasma 15N' and 93.8% of that in the corpuscles is precipitable in trichloric acetic acid. The atom-% 15N' of histidine in the total blood remained unchanged in dependence on the butchering time. The 15N amount in lysine and arginine and that in the non-basic amino acids decreased inconsiderably in the period between 12 h and 108 h after the last 15N' wheat feeding.

Amino Acids↗

A comparison of two types of anaesthesia on the endocrine and metabolic responses to anaesthesia and surgery.

The influence of halothane-nitrous oxide anaesthesia and normotensive epidural analgesia (level of sensory block T8-T10), respectively, on the plasma concentrations of adrenocorticotrophic hormone (ACTH), beta-lipotropin (beta-LPH), cortisol, dehydroepiandrosterone (DHA) and aldosterone as well as on the metabolites glucose, lactate and free fatty acids (FFA) was studied in 20 healthy patients who underwent elective orthopaedic procedures on the lower limbs. ACTH and beta-LPH concentrations in plasma rose significantly (P less than 0.001) during halothane-nitrous oxide anaesthesia. DHA secretion closely followed the secretory profile of cortisol. Increased renin levels and increased ACTH release seemed to be responsible for increased aldosterone secretion, intra-operatively. The hormonally induced rise of glycogenolysis and lipolysis did not produce important intra-operative increases in metabolite concentrations in the blood. In normotensive epidural analgesia no significant increase in stress response could be demonstrated, even with low levels of sensory block.

Adrenocorticotropic Hormone↗