Safety and efficacy of percutaneous injection of polyurethane elastomer (MPU) plugs for vas occlusion in man.

This report describes the safety and efficacy of the procedure for percutaneous injection of medical-grade polyurethane elastomer (MPU) to form plugs in the vas deferens. The injection of 0.16-0.22 ml MPU in 53 men resulted in occlusion and azoospermia in 85% of the men after 12 months; 96% achieved azoospermia by 2 years. The success rate of the method and the rate of sperm suppression to azoospermia depended on the shapes of the plugs; this was determined by palpation after insertion. There were few complications and the results are discussed in terms of the reversibility potential of this method.

PIP: In China, physicians performed percutaneous injection of medical-grade polyurethane (MPU) in 53 men at the National Research Institute for Family Planning in Beijing and followed them for 2 years to evaluate the safety and efficacy of MPU vas occlusion. The injection of 1% procaine solution was used to kill residual spermatozoa in the distal reproductive tract. 1 year and within-subject fructose levels did not fluctuate greatly. 85% of the men reached azoospermia within 1 year after vas occlusion. 96% were azoospermic at 18 months. 2 men still had spermatozoa in the semen after 2 years (8-48 million ml-1). Both MPU plugs in most men (74%) had a regular shape. All of these men reached azoospermia by 18 months. 91% of the 11 men who had 1 regular and 1 irregular shaped MPU plug reached azoospermia by 18 months. This percentage fell to 67% for the 3 men whose MPU plugs were both irregular. The physicians had removed irregularly shaped MPU plugs in 5 men earlier and the elastomer filled the vas lumen and the surrounding vas surface. Recanalization did not occur in these 5 patients. 1 man with MPU vas occlusion developed a hematoma. 3 men experienced hemaspermia within 2 weeks after vas occlusion, but medication made it disappear within 4 weeks. Injection of 1% procaine solution may have damaged the seminal vesicles, resulting in the hemaspermia. Longterm complications did not occur.

Penicillinase Studies on L-Phase Variants, G-Phase Variants, and Reverted Strains of Staphylococcus aureus.

L-phase variants and small colony (G-phase) variants derived from penicillinase-producing Staphylococcus aureus strains were tested for penicillinase (beta lactamase) production. A refined variation of the modified Gots test for penicillinase was used to demonstrate penicillinase synthesis. Penicillinase synthesis was reduced in L-phase variants and G-phase variants when compared to parental strains. After reversion of variants to vegetative stages had been induced, revertants were tested for production of penicillinase, coagulase, and alpha hemolysin, mannitol fermentation, and pigment production, and comparisons were made between parent and reverted vegetative forms. All revertants of G-phase variants retained penicillinase activity. Most revertants of L-phase variants showed reduction or loss of penicillinase activity. Retention of coagulase activity, alpha hemolysin production, mannitol fermentation, pigmentation, and phage type varied among revertants.

Microbioassay of antimicrobial agents.

A previously described agar-diffusion technique for microbioassay of antimicrobial agents has been modified to increase sensitivity of the technique and to extend the range of antimicrobial agents to which it is applicable. This microtechnique requires only 0.02 ml of an unknown test sample for assay, and is capable of measuring minute concentrations of antibiotics in buffer, serum, and urine. In some cases, up to a 20-fold increase in sensitivity is gained relative to other published standardized methods and the error of this method is less than +/-5%. Buffer standard curves have been established for this technique, concurrently with serum standard curves, yielding information on antimicrobial serum-binding and demonstrating linearity of the data points compared to the estimated regression line for the microconcentration ranges covered by this technique. This microassay technique is particularly well suited for pediatric research and for other investigations where sample volumes are small and quantitative accuracy is desired. Dilution of clinical samples to attain concentrations falling with the range of this assay makes the technique readily adaptable and suitable for general clinical pharmacological studies. The microassay technique has been standardized in buffer solutions and in normal human serum pools for the following antimicrobials: ampicillin, methicillin, penicillin G, oxacillin, cloxacillin, dicloxacillin, cephaloglycin, cephalexin, cephaloridine, cephalothin, erythromycin, rifamycin amino methyl piperazine, kanamycin, neomycin, streptomycin, colistin, polymyxin B, doxycycline, minocycline, oxytetracycline, tetracycline, and chloramphenicol.