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Biomedical subjects

W Dick

Publications and source records attributed to W Dick.

At least 235 records · Page 13Linked to original sources
PubMed1983

Influence of methoxy-substitution of beta-lactam compounds on the interaction with various beta-lactamases.

The interaction of 6 alpha-(temocillin) and 7 alpha-methoxy substituted (cefoxitin) beta-lactam compounds with various beta-lactamases was studied employing enzyme kinetics and compared to that of unsubstituted compounds. Both chromosomally mediated enzymes from Enterobacter cloacae and Citrobacter freundii were competitively inhibited by the methoxy-substituted compounds. Higher concentrations of cefoxitin caused a competitive inhibition of the plasmid-mediated Tem-1 enzyme, whereas temocillin led to a non-competitive inhibition of the Tem-1 enzyme. These results indicate that the discrepancies in the interaction on the above mentioned compounds have to be attributed to the different molecular structure of the beta-lactam nucleus. Moreover, no predictions can be made on the basis of an analogy between 6 alpha-methoxy-penams and 7 alpha-methoxy cephems.

Binding, Competitive↗
PubMed1983

Investigations on beta-lactamase stability of recently developed beta-lactam compounds: study of enzyme kinetics.

The plasmid-mediated TEM-1 enzyme (E. coli K12 R6K) and chromosomally mediated enzymes from Enterobacter cloacae (IEP 8.5) and Citrobacter freundii (IEP 9.5) were highly purified. Enzyme kinetics were studied with various therapeutic compounds as substrates and lamoxactam, azthreonam, and N-formimidoyl thienamycin as inhibitors. Lamoxactam and azthreonam failed to inhibit the TEM-1 enzyme, whereas N-formimidoyl thienamycin was a competitive inhibitor. KI was 5 mumol/l--thus corresponding to KM--and independent of the substrate. With respect to chromosomally mediated enzymes, there was a time-dependent inhibition of beta-lactam hydrolysis. KI ranged from 0.06 to 0.2 mumol/l in dependence of the inhibitor. Enzyme kinetics suggested a non-competitive type of inhibition thus indicating that binding of these compounds to both chromosomally mediated enzymes must be followed by a further reaction step. It is evident that the stability against beta-lactamases of recently developed compounds is based on different mechanisms--characteristic for the enzyme being considered.

Anti-Bacterial Agents↗
PubMed1983

[Clinical experimental studies of postoperative infusion analgesia].

30 postoperative patients, who had undergone abdominal gynaecological surgery with standard general anaesthesia were randomly divided into three groups and received, in the recovery ward, a continuous infusion of either pentazocine, piritramid, or ketamine. The patients rated their pain on a 15 cm pain analogue score. Group I pentazocine: Mean dosage on the day of operation 0.12 mg/kg/h, 0.1 mg/kg/h on the first and only 0.07 mg/kg/h on the second postoperative day. Pentazocine blood levels were on average 50 micrograms/l. Group II piritramid: Mean dosage on the day of operation 0.038 mg/kg/h, 0.024 mg/kg/h on the first and 0.019 mg/kg/h on the second postoperative day. Blood levels of piritramid were not determined because there is no satisfactory assay available. Group III ketamine: mean dosage on the day of operation 0.32 mg/kg/h, 0.28 mg/kg/h on the first and 0.29 mg/kg/h on the second postoperative day. Ketamine blood levels lay between 120 and 180 micrograms/l. The three analgesics did not cause any important haemodynamic or respiratory side effects. Pentazocine and piritramid were the most effective analgesics, ketamine was the least effective with a high incidence of side effects.

Adult↗
PubMed1983

[Peridural morphine analgesia: effects and pharmacokinetics. A double-blind study in vaginal hysterectomy patients].

In a controlled prospective double-blind-study we were able to show that the analgesic duration of epidurally applied morphine is more than four fold longer lasting than intravenous morphine. We found similar pharmacokinetics in both groups, suggesting a rapid absorption of epidurally applied morphine into the vascular system. The identical pharmacokinetics of intravenous and epidurally applied morphine suggest that only small amounts of morphine diffuse across the dura to the spinal cord, where it produces a long lasting analgesia at the opiate receptors. The comparison of serum morphine levels in patients who reported a very short lasting and very long lasting analgesia gave us no pharmacokinetic explanation for this difference.

Adult↗
PubMed1983

[Intramuscular ketamine analgesia in emergency patients. I. Clinico--pharmacokinetic study].

Effective analgesia under conditions of emergency and disaster is still a problem which can be considered as unsolved. The i.m. administration of ketamine in subanaesthetic doses could be one step forward, particularly in regard to a possible application by paramedical personnel. In order to evaluate this hypothesis, we compared 2 groups of 6 patients each, who received either 0.5 mg/kg or 1 mg/kg ketamine respectively i.m. for p.o. pain relief after tonsillectomies. The analgesic efficacy, the levels of consciousness, the blood pressure values and the ketamine plasma levels demonstrated, that effective analgesia can be obtained within 10 min following either dose. The dosage of 1 mg/kg however was followed by a transient impairment of the levels of consciousness. The pharmacokinetic data may lead to the conclusion that analgesia starts above plasma levels of 100 ng/ml. Important side effects were not be observed in these few cases. A further study, which has almost been completed, will demonstrate whether the same results apply to emergency out-patients suffering from fractures, burns etc.

Emergencies↗
PubMed1983

Clinical experimental studies of postoperative infusion analgesia.

Thirty postoperative patients, after undergoing abdominal hysterectomy and standard general anesthesia, were randomly allocated to three groups and received, in the recovery ward, a continuous infusion of either pentazocine, piritramide, or ketamine. The patients rated their pain on a 15-cm visual analog scale. Patients in group 1 received pentazocine. Mean dosage was 0.12 mg/kg/hr on the day of operation, 0.1 mg/kg/hr on the first postoperative day, and only 0.07 mg/kg/hr on the second postoperative day. Pentazocine blood levels averaged 50 micrograms/L. Patients in group 2 received piritramide. Mean dosage was 0.038 mg/kg/hr on the day of operation, 0.024 mg/kg/hr on the first postoperative day, and 0.019 mg/kg/hr on the second postoperative day. Blood levels of piritramide were not determined because no satisfactory assay is available. Patients in group 3 received ketamine. Mean dosage was 0.32 mg/kg/hr on the day of operation, 0.28 mg/kg/hr on the first postoperative day, and 0.29 mg/kg/hr on the second postoperative day. Ketamine blood levels ranged between 120 and 180 micrograms/L. None of the three analgesics caused any important hemodynamic or respiratory side effects. Pentazocine and piritramide were more effective analgesics than ketamine was. Ketamine also had a higher incidence of side effects.

Adult↗
PubMed1983

[Clinical studies on the effect of various drugs on cardiocirculatory behavior during the induction phase of intubation anesthesia].

In a randomized study on 150 patients (ASA 1) undergoing induction of anaesthesia, the effects of Fentanyl (0.1 mg), the combination of Fentanyl (0.1 mg) and Droperidol (5 mg) (Innovar, Thalamonal) and Atropine (0.01 mg/kg b.w.) alone on cardiocirculatory parameters were studied. Induction and intubation were carried out with Thiopentone and Succinylcholine. All patients were aged between 18 and 50 years. In addition to continuous ECG recording of standard leads I-III, blood pressure measurements (Riva-Rocci), capillary blood gases and serum potassium were estimated at regular intervals. Prior to intubation Atropine caused arrhythmias in 10% and during intubation in 40%, half of which occurred repeatedly. In comparison, the control group showed arrhythmias in only 28% at intubation time. The median value of the rate pressure products rose before intubation time to levels of almost 20,000 units whereas the control group reached the same high product only during intubation. Cardiac rhythm proved most stable using Fentanyl, the systolic, diastolic and mean blood pressure changes were significantly lower than in those groups without an additional analgesic. With Fentanyl and Atropine the increase of all haemodynamic parameters was less pronounced than in the control group given Atropine only. Comparison of the Fentanyl groups showed only a significantly lower arterial mean pressure when Atropine was given, the other parameters were similar. Using Innovar alone, 4 cases of severe and 1 of mild rhythm disturbances appeared, while with Innovar plus Atropine only 2 cases of mild and 1 of repeated extrasystoles occurred. In the Atropine-free groups, the addition of Innovar only caused a lesser increase in the heart rate, while the remaining parameters did not differ.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1983

Cementless fixation of "isoelastic" hip endoprostheses manufactured from plastic materials.

Nine years of clinical experience with an "isoelastic" shaft prosthesis manufactured using polyacetal resin reveal that for the transmission of forces from the pelvis through the femoral head and neck into the femoral shaft, some rigidity of the proximal part of the prosthesis is necessary. The object is to eliminate micromovements, which lead to bone resorption and implant loosening. However, elasticity greater than that present in metallic implants prevents stress concentrations and disuse stress protection atrophy of the bone. Greater elasticity of the prosthesis, which can be achieved by plastic materials, makes possible a more even, harmonious distribution of the forces transmitted from the implant to the bone and vice versa. A more elastic implant can also act as a better shock absorber than a rigid one. The results in 627 cementless polyethylene cups after a maximum observation period of 5.5 years reveal good incorporation and no aseptic loosening. Especially favorable results occurred in 61 cases by replacing loosened cemented cups with bone grafts and cementless polyethylene cups. On the femoral shaft side too high an elasticity in the proximal part of the prosthesis led to bone resorption and loosening with the first model of the prosthesis. By reinforcing the proximal part of the femoral component, much better results were obtained. The isoelastic femoral shaft, however, is in an early stage of experimentation.

Acetabulum↗
PubMed1982

[Lysozyme: basic facts and diagnostic importance].

The determination of lysozyme has been shown to be more relevant than assumed until now. It can be used as a marker in the therapy of acute and chronic urinary tract infections. The determination of lysozyme in cerebro spinal fluid and blood serum are helpful to differentiate between bacterial and aseptic meningitides or infections. Elevated fecal lysozyme excretion in adolescents are an indicator for a chronic inflammatory bowel disease. Control of fecal lysozyme excretion can be used as a marker for a relapse and to monitor therapeutic efficiency in patients with inflammatory bowel disease. A consistent high level of fecal lysozyme excretion in adults over the age of 40 is an indicator for possible colorectal tumors and warrants further thorough investigation.

Adolescent↗
PubMed1982

A rapid method for functional determination of C1 esterase inhibitor in plasma.

A functional determination of C1 esterase inhibitor (C1 INH) can be easily performed with an amidolytic assay by monitoring the inactivation of plasma kallikrein. In patients with urticaria as well as in healthy donors kallikrein inactivation, determined as the ratio of kallikrein activity at t60/t15, was found to be 0.47 +/- 0.06; in patients with hereditary angioneurotic edema (HANE). However, it amounted to 0.80 +/- 0.06. There was a good correlation between the inactivation rate of kallikrein and the protein levels of C1 INH (r = -0.93, p less than 0.001). In patients with HANE, levels of plasma kallikrein were slightly decreased (mean = 0.37 +/- 0.11 U/ml, normal mean = 0.47 +/- 0.09 U/ml), but still sufficient for monitoring kallikrein inactivation. In the case of one patient with functionally inactive C1 INH protein, the inactivation of kallikrein was impaired as in the conventional form of the disease.

Angioedema↗
PubMed1982

Cementless fixation of polyethylene acetabular component in total hip arthroplasty.

A new concept of cementless fixation of a polyethylene acetabular component for total hip arthroplasty is presented. The spherical cup is fixed directly to the subchondral bone of the acetabulum by means of two pegs and screws. The polyethylene in direct contact to the bone adjusts to the deformation of the pelvis (Isoelasticity). Bone grows into the indentations of the outer surface of the implant. The elastic cup does not interfere with the physiological stress patterns of the hip joint so that a stable "biomechanical incorporation" of the implant is achieved. A follow-up of the first 250 cementless fixed polyethylene cups with an observation period of six months to four years with an average of 19 months is reported. So far no aseptic loosening of the implant has occurred.

Acetabulum↗
PubMed1982

[The effect of fenoterol on the incidence of arrhythmias during Caesarean section (author's transl)].

Beta-sympathomimetic tocolysis is an important part of modern obstetric therapy. Severe cardio-vascular complications have been described however, when inhalational anaesthesia was given following fenoterol-verapamil therapy. Alterations in clinical; cardiovascular parameters were measured in a prospective study on healthy women who had to undergo caesarean section and who had been treated with fenoterol-verapamil until the time of anaesthesia. The patients were given either halothane or enflurane as inhalational anaesthetic, and either an atropine premedication or none at all. Severe cardiovascular disturbances such as frequent extrasystole, arrhythmias or marked falls in blood pressure were not noted either during induction, whether following atropine or not, or during the course of anaesthesia with either 0.5 vol% halothane or 1.0 vol% enflurane.

Anesthesia, General↗
PubMed1982

An amidolytic assay for determination of alpha 1-antitrypsin in serum and in cerebrospinal fluid.

An amidolytic assay using the chromogenic substrate tosyl-glycyl-prolyl-lysine-4-nitranilide acetate (Chromozym PL) has been studied for the determination of alpha 1-antitrypsin in serum and in cerebrospinal fluid (CSF). It was found that binding of trypsin to alpha 2-macroglobulin has to be taken into consideration when alpha 1-antitrypsin is determined by an amidolytic assay. In serum this accounts for 7.4 +/- 3.2% and in CSF 2.8 +/- 1.8% of the total antitrypsin capacity. The reference range of alpha 1-antitrypsin in sera was found to be x = 60.3 +/- 20.8 kIU/l, and in CSF mean = 186 +/- 99 IU/l. Within-run precision showed a C.V. of 1.36% in sera, and a C.V. of 1.86% in CSF. There was a good correlation with immunochemical methods: r = 0.946 in 65 sera (p less than 0.001) and r = 0.986 in 55 samples of CSF (p less than 0.001).

Chromogenic Compounds↗