[Two-dimensional diffusion method for determining antimicrobial agents (author's transl)]

Intending to improve the accuracy of determination of antibiotics, a two-dimensional diffusion method using large agar plate was introduced. Three antimicrobial agents, ampicillin, PC-904, and tobramycin, were used. Inhibition zones of B. subtilis on the agar plate were measured which were formed as a result of diffusion of these agents. The relationship between the concentration of antimicrobials and the size of inhibition zones was studied. Plotting the data-points on the graph, it was predicted that there might be a relationship of quadratic equation between the diameter of inhibition zone and the logarithm of concentration of the agents. On the other hand, mathematical considerations were taken to find out a physical principle or an equation which governs the diffusion of antibiotics in the agar. Assuming that antibiotics spreads in the agar after the principle of simple diffusion, an equation was lead which shows how the antibiotics distributes in the agar in relation to time. The equation was written as, (formula: see text) where, S is amount of antibiotics, D diffusion constant, r distance from the center of diffusion, t period during which the diffusion proceeds. As a result of the mathematical calculations mentioned, it was confirmed that the relation between the size of zones and the logarithm of concentration of antibiotics is described by a quadratic equation as predicted on the basis of experimental data.

Kinetic analysis of plasma TSH dynamics after TRH stimulation

Kinetic analysis of the time course of plasma TSH after TRH stimulation was performed by means of a single compartment model with first order input. This kinetic model showed satisfactory fit to the data, and was found to be useful enough for the characterization of plasma TSH dynamics. In endocrinologically normal short children, the amount of TSH release per unit volume of distribution space (Q0/V), the rate constant for the TSH release (alpha), and the rate constant for TSH elimination (beta) were averaged 23.4 microU/ml, 6.981 hr-1 and 0.813 hr-1, respectively. Elevated Q0/V values with lowered alpha and beta were obtained in the hypothyroid children. Variable results, with the exception of low alpha values, were obtained in the children with pituitary dwarfism.

[Pharmacokinetics and results of clinical administration of CS-1170. I. Pharmacokinetics of CS-1170 (author's transl)]

(1) When 20.8 approximately 34.7 mg/kg body weight of CS-1170 were instilled intravenously for 30 minutes to one hour, peak levels were obtained on completion of the intravenous drip in the range 85.7 approximately 1,117.3 microgram/ml. (2) The half life was 22 approximately 49 minutes which is very rapid. (3) The kidney clearance was 6.8 approximately 104.8 ml/min. (4) The total clearance was 5.9 approximately 111.5 ml/min, showing correlation with the kidney clearance. (5) The apparent distributional capacity was 0.3 approximately 4.3 liters, showing a strong correlation with body weight.

Pharmacokinetics of intramuscular carbenicillin

A 500 mg intramuscular dose of carbenicillin produced peak levels averaging 147 microgram/ml after three hours in the first day full-term newborn infants, and 172 microgram/ml after one to two hours in infants five days of age. The fall of blood levels thereafter was delayed and serum half-life averaged 4.2 and 2.2 hours in both groups, almost four times and twice as long, respectively, as that reported in adults. Absorption from the injected site was also delayed in young newborns, as was shown by the delayed serum peak and small estimated absorption rate constant. This must be taken into consideration if the intramuscular route is chosen in young newborn infants. On the basis of serum half-life, an administration interval of 12 hours was recommended for newborns younger than four days, and eight hours for those five days of age or more.

[Pharmacokinetics and results of clinical administration of CS-1170. II. Results of clinical administration of CS-1170 (author's transl)]

The intravenous preparation of CS-1170 was administered in 9 cases of pediatric disease and was excellent or good in 5 cases (55.6%). It was poor in 3 of 4 cases of Mycoplasma pneumonia. We think that the dose of 50 mg/kg/day can exert an effect regardless of the intensity of symptoms. Through our present experiences with the excellent or good cases, an intravenous drip or intratracheal injection for 3 approximately 5 days is effective. Although there was no abnormality in the biochemistry or electrolyte findings before or after administration, eruption developed in one of the cases in which the drug was administered for 6 days.

Surveillance and follow-up of patients with implanted cardiac pacemaker by telephone transmission

A follow-up study on pacemaker function in 15 patients with implanted cardiac pacemaker has been performed by telephone transmission. The transmitting set consisting of electrocardiograph, pacemaker pulse modulator and acoustic coupler was manipulated by the patients themselves. ECG, pacemaker pulse, and pulse rate were simultaneously transmitted through 1 channel to the receiver in our clinic. Of 56 patients with pacemaker, 15 patients were surveyed by telephone transmission. In these patients battery exhaustion was detected in 3, competition in 2, and lead fracture in 1. The fact that surveillance and follow-up of the patients with implanted cardiac pacemaker could be carried out by telephone transmission as well as by clinic visitation tells us that the telephone transmission is a useful method and plays an important role in a pacemaker clinic. Moreover our study established its further usefulness in the patient's preference due to difficulties in travelling to the pacemaker clinic and in reducing patient's anxiety.

Dosage schedule of gentamicin for chronic renal insufficiency in children

Gentamicin was given to paediatric patients with chronic renal disease complicated by infections by Gram-negative organisms, in which renal function varied from normal to severely insufficient. Peak serum levels after an intramuscular dose of 1 mg/kg body weight ranged from 3.1 to 9.4 microgram/ml, which appeared adequate for therapy. The peak value was not related to the renal function of the individual patients. The serum half-life of gentamicin correlated inversely with the value for endogenous creatinine clearance. A diagram for the estimation of the serum half-life of gentamicin using the creatinine clearance value is presented. As a practical guide, it is recommended that the dose of gentamicin in children with renal function impairment be 1 mg/kg given intramuscularly and that the interval between doses be almost three times as long as the serum half-life, which can be estimated by means of the diagram for individual patients. The accuracy and safety of this method were confirmed by treating children with this adjusted dosage schedule.

Pharmacokinetic model for serum concentrations of ampicillin in the newborn infant

The time course of ampicillin concentrations in the sera of three newborn infants during and upon termination of intravenous infusion at a constant rate can be described by a two-compartment pharmacokinetic model. The parameters of the model were determined by simultaneously fitting the serum concentration data obtained during and after the infusion by means of a nonlinear regression program with the aid of a digital computer. The half-life of ampicillin in the infants ranged from 2.1 to 2.9 hr; these values are more than twice those observed in adults with normal renal function.