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Biomedical subjects

D Adam

Publications and source records attributed to D Adam.

At least 181 records · Page 10Linked to original sources
PubMed1987

3-D ventricular myocardial electrical excitation: a minimal orthogonal pathways model.

This study is part of our attempt to develop a fast-responding interactive computer simulator of the left ventricle (LV) which describes the spatial and temporal myocardial characteristics and the global performance of the LV, accounting for the continuous interactions between the electrical activation sequence, fiber mechanics, blood perfusion and transmural metabolism and oxygen demand. Here, the activation propagation front throughout the healthy 3-dimensional LV myocardium is simulated in a macro global level by utilizing an analytical model based on the principle of the propagation of the electric activation signal along minimal pathways in an elliptically assumed LV geometry. The Purkinje network dominates the propagation at the endocardial layer while three orthogonal directions of propagation are assumed within the myocardium. The shortest path consists of the geodetic line at the endocardial layer and the normal that connects the endocardium with the point considered. The generated three-dimensional propagation front maps are in fair agreement with reported experimental data. The study thus presents a new approach that permits a quick reconstruction of the 3-D isochrons in a relatively simple but useful model of the normal heart.

Computer Simulation↗
PubMed1987

Concentrations of ticarcillin and clavulanic acid in human bone after prophylactic administration of 5.2 g of timentin.

The penetration of ticarcillin and clavulanate into their distribution space within human bone was determined after prophylactic administration of 5.2 g of timentin (5 g of ticarcillin plus 0.2 g of clavulanic acid) to 20 patients undergoing hip surgery. All samples were taken 45 to 85 min postadministration. The mean concentrations of ticarcillin in spongiosa and corticalis bone were 57.1 and 70.5 mg/kg, respectively; those of clavulanic acid were 17.8 and 32.5 mg/kg, respectively. No infections occurred in these patients.

Aged↗
PubMed1987

In vitro activity and concentrations in serum, urine, prostatic secretion and adenoma tissue of ofloxacin in urological patients.

Studies in vitro showed that at concentrations of 1 and 4 mg/L ofloxacin inhibited 94 and 99% of the Gram-negative pathogens in isolates cultured from the urine of patients with complicated urinary tract infections (UTI). Against Gram-positive bacteria, 60 and 100% were inhibited at the corresponding concentrations. Comparisons of the MIC90 values of 8 quinolones showed the decreasing order of in vitro antibacterial activity to be ciprofloxacin, ofloxacin, norfloxacin, pefloxacin, enoxacin, pipemidic acid, nalidixic acid and cinoxacin. After an oral dose of ofloxacin 400mg, the mean peak serum concentration in 10 elderly patients was 5.5 mg/L and mean renal excretion during 24 hours was 41%. In 17 patients undergoing transurethral resection of the prostate, ofloxacin 400mg was given for perioperative prophylaxis. Two to 4.5 hours after administration, the median concentrations in prostatic secretion (5 patients) and prostatic adenoma tissue were 4.0 mg/L and 4.1 mg/kg, respectively. The corresponding serum concentrations of ofloxacin were 3.4 and 3.9 mg/L, respectively. In a group of 10 patients, 14.5 to 19.5 hours after oral administration of ofloxacin 400mg the median serum and prostatic adenoma tissue concentrations of ofloxacin were 1.9 mg/L and 1.2 mg/kg, respectively. The in vitro activity of ofloxacin concentrations attained in serum, urine, prostatic secretion and adenoma tissue show that it appears to be well suited for the treatment of complicated UTI.

Adenoma↗
PubMed1986

[In vitro activity, serum, urine and prostatic adenoma concentrations of ofloxacin in urologic patients with complicated urinary tract infections].

The minimal inhibitory concentrations (MIC) of ofloxacin against 400 isolates cultured from the urine of urological patients with complicated urinary tract infections (UTI) resulted in an inhibition of 94% (99%) of the gram-negative strains at a concentration of 1 mg/l (2 mg/l) and an inhibition of 59% (100%) of the gram-positive strains at a concentration of 1 mg/l (4 mg/l). According to the MIC 90% values, the corresponding grade of activity was as follows: ciprofloxacin, ofloxacin, norfloxacin, pefloxacin, enoxacin, pipemidic acid, enoxacin and nalidixic acid. After an oral dose of 400 mg of ofloxacin, the mean peak serum concentration of ten patients was 5.5 mg/l. The mean renal excretion during 24 hours was 41%. In ten patients undergoing transurethral resection of the prostate, the median serum concentration was 1.87 mg/l and the median prostatic adenoma tissue concentration 1.20 mg/kg 14.5 to 19 hours after oral administration of 400 mg ofloxacin. Due to the in vitro activity and the concentrations obtained in serum, urine and tissue, ofloxacin appears to be well suited for treatment of complicated UTI.

Aged↗
PubMed1986

[Imipenem/cilastatin: in vitro activity, concentrations in plasma and prostatic adenoma and therapeutic results in patients with complicated urinary tract infections].

Minimal inhibitory concentrations (MICs) of imipenem, ceftazidime, piperacillin, tobramycin, azthreonam and carumonam were assessed for 400 urinary isolates from hospitalized patients with complicated and/or nosocomial urinary tract infections yielding greater than or equal to 10(5) colony forming units (cfu). More than 90% of the gram-negative pathogens were sensitive to all the antibiotics tested. However, only imipenem and piperacillin exhibited MIC90 values in the therapeutic range for gram-positive pathogens (approximately half of which were staphylococci and enterococci). Perioperative prophylaxis with 0.5 g imipenem/cilastatin administered at different time intervals before the operation (up to six hours) was performed in patients undergoing resection (n = 31), respectively enucleation (n = 1) of a prostatic adenoma or lithotriptic treatment (n = 4). Imipenem yielded peak plasma concentrations of 12.2 to 134.8 mg/l (mean 49.4 mg/l). The estimated half life time in these patients was approximately three hours. Considerable intra as well as interindividual variations were found for imipenem concentrations in prostatic adenoma. However, they were sufficiently high to reach sensitive pathogens (MICs up to 1 mg/l) for up to two-and-a-half hours. Up to six hours after dosing the concentrations in prostatic secretions ranged between 1 and 2 mg/l. A total of 20 urological patients suffering from complicated urinary tract infections (15 men, five women) received a short-term i.v. infusion of 0.5 mg imipenem/cilastatin t.i.d. for seven to 16 days (median seven days). In all these patients urines were sterile during therapy as well as one to two days after therapy. Follow-up examinations performed seven to ten days after the end of treatment in 19 of these patients showed ten patients to be free of infection (55%); these patients were classified as success. Seven patients (37%) presented a relapse (same pathogen) and two patients (10%) a re-infection (different pathogen). Imipenem/cilastatin was well tolerated locally and systemically.

Adult↗
PubMed1986

Clinical perspective of antibacterial usage.

Under clinical conditions there are two main aspects of antibacterial usage: community or hospital acquired infection. If there is not any severe underlying disease in general it is not difficult to treat a community acquired infection for example a pneumonia successfully with any of the available antiinfective drugs if the strain is sensitive. In case of nosocomial infections when ever possible the causative organism should be identified and antimicrobial testing must be performed. It must be considered that the host response is variable at the extremes of life for example infancy and old age but also in immunocompromised patients and patients under stress conditions like polytrauma and difficult and long time operations. Diffusion into the site of infection may be achieved more readily with one agent than with another. Resistance that emerges clinically usually does so through either selection of resistant strains in the environment or the genetic exchange of material between species. Most clinically important resistant species are selected, as clearly shown by the differences in antibiotic sensitivity patterns of hospital--versus community-acquired organisms.

Age Factors↗
PubMed1985

Assessment of autonomic function in humans by heart rate spectral analysis.

Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.

Adult↗
PubMed1985

Therapeutic results and tissue concentrations of temocillin in surgical patients.

Temocillin, a new beta-lactamase-stable penicillin, was administered in a dosage of 2g twice daily to 25 biliary surgery patients in whom potential septic complications were a concern. Clinical efficacy was assessed as 'very good' in 23 patients. In one patient there was a disorder of wound healing and in another a staphylococcal bronchial pneumonia developed postoperatively. Temocillin was tolerated very well, and no side effects were observed. 12 hours after administration of temocillin 2g intravenously to surgical patients the mean serum concentration was 22.44 (+/- 10.26) mg/L. The median half-life was 3.86 hours (+/- 1.84) hours. Mean concentrations of 12.44 and 38.59 mg/L were measured up to the twelfth hour in the wound secretions and peritoneal secretions, respectively. In skin, fat, fascia, muscle and gallbladder wall, temocillin concentrations greater than the inhibitory concentrations of most Gram-negative bacteria were demonstrated after 1 and 2 hours.

Adult↗
PubMed1985

[The effect of infusion rate on pharmacokinetic parameters of azlocillin and mezlocillin].

Azlocillin (Securopen) and mezlocillin (Baypen) were given to 3 healthy subjects as intravenous infusion. The dose of 4 g was administered to each person within 5, 15, and 30 min in a randomized crossover design. Using HPLC the unchanged penicillin antibiotics were determined quantitatively, their metabolites were assessed qualitatively. The same specimens were also studied by means of a bioassay (agar diffusion technique). Both methods yielded similar serum and urine concentrations besides the urinary excretion of azlocillin. Here the bioassay measured higher amounts indicating an antibacterially active metabolite being excreted in the urine. No dependence upon infusion time was found. Since both drugs were tested with the same dosis in the same subjects, their pharmacokinetic parameters could be compared: mezlocillin, being more lipophilic than azlocillin, showed a higher volume of distribution and therefore lower serum concentrations. Renal clearance was the same for both drugs, but mezlocillin was excreted to a smaller extent in the urine. Higher total clearance and shorter elimination half-life of mezlocillin indicate a greater extrarenal elimination. The results suggest fast application of both penicillins. There is no pharmacokinetic reason for a prolongation of infusion times.

Adult↗
PubMed1984

Cefmenoxime in surgical infections: treatment and penetration into peritoneal fluid and wound secretions.

Sixty patients (23 men and 37 women) with a median age of 56.7 years (range 20 to 80) and a median weight of 69 kg were treated with cefmenoxime as short-term perioperative prophylaxis. Patients were undergoing surgery for an infected gallbladder, bile duct, or colon or were being treated for local or diffuse peritonitis and soft tissue infections. Overall clinical efficacy including very good and good results could be achieved in 88.3 percent. Moderate clinical efficacy was achieved in six cases, two of which were due to Pseudomonas aeruginosa. In 38 of 60 patients an antibiogram could be performed before and after therapy. Of the isolated 46 strains, 40 pathogens (86.95 percent) were eradicated during cefmenoxime treatment and in two cases a replacement was observed. After one hour, peak concentrations in serum could be reached with over 70 micrograms/ml.

Adult↗