Evaluation of quality of lateral full spine radiographs: a statistical study.

OBJECTIVE: This study examines the effects of filtration on X-ray quality in 287 lateral full spine radiographs of human subjects. The impact of the subject's sex and age on the effects of filtration was also examined. DESIGN: X rays obtained with and without filtration were selected at random from various chiropractic clinics in North America. Five college instructors from various clinical backgrounds classified each film as adequate film quality, or as over- or underexposed in each of the cervical, thoracic, lumbar and sacral spinal regions. RESULTS: Log linear analyses showed that the use of filtration produced the best overall film quality, and that film quality decreased as age increased in all spinal regions, regardless of filtration usage. A higher percentage of films of subjects less than 54 yr of age were judged to be of adequate quality when filtration was used. Films of male subjects had better quality in the lower spinal regions; films of females were better in the upper regions. CONCLUSIONS: By the evidence supported by the statistical analyses, it is suggested that lateral full spine films may only be used as a means for postural screenings if filtration is always used, and to take the sex and age of the patient into account in deciding whether to change technique exposure factors or to use sectional views, which would increase the probability of better quality films.

Pharmacokinetic determinants of penicillin cure of gonococcal urethritis.

In a 1964 study of the pharmacokinetic determinants of penicillin cure of gonococcal urethritis, 45 male prisoner volunteers were experimentally infected with strains of Neisseria gonorrhoeae having known in vitro penicillin susceptibility. After developing urethritis, subjects received intramuscular penicillin G and had serum samples obtained serially to determine penicillin concentration. Using a multiple regression technique, we studied patient-associated parameters and parameters of the serum penicillin curves to determine the best predictors of treatment results. Cure was best predicted by the time the serum penicillin concentration remained above three to four times the penicillin minimum inhibitory concentration of the infecting strain (probability of correct classification, >0.80). Those cured had serum penicillin concentrations which remained in this range for means of 7 to 10 h. Our findings confirm principles of antimicrobial therapy derived from animal models and may have application in studying therapy of gonorrhea and other infectious diseases.

Cellular fatty acids of pathogenic Neisseria.

The cellular fatty acid composition of 20 isolates of Neisseria gonorrhoeae and 21 isolates of N. meningitidis was examined by gas-liquid chromatography. Each isolate of the two species possessed similar fatty acid profiles which were characterized by five major acids, accounting for 80 to 85% of the total. The three most abundant acids in each species were palmitic, palmitoleic, and beta-hydroxylauric acids; lauric and myristic acids were the next most abundant. The presence of large amounts of beta-hydroxylauric acid (20% or greater) and the relative concentrations of the other four major acids appear to be useful markers for distinguishing N. gonorrhoeae and N. meningitidis fatty acids from those of other bacteria.

Separation of Treponema pallidum from tissue debris through continuous-particle electrophoresis.

Treponema pallidum can only be cultured in living animal tissue, such as rabbit testes. However, the extract of these organisms from the testicular material leaves the T. pallidum contaminated with tissue debris. This paper describes the separation of T. pallidum from the debris by continuous-particle electrophoresis. The importance of equilibration time before electrophoresis is discussed.

Reactivity of two selected antigens of Neisseria gonorrhoeae.

Two antigen preparations, the soluble antigen and a fraction 1 thereof, isolated in the course of a systematic study of the various antigens of the virulent gonococcus, have been investigated for their ability to serve as antigens for the detection of antibody in patients infected with the gonococcus. The soluble antigen was reactive with 88.2% of the sera from infected females, and fraction 1 was reactive with 71.6% of the sera. Of sera from infected males, only 27.6% reacted with the soluble antigen and only 20.4% with fraction 1. Of sera from individuals presumed free of gonococcal infection, approximately 4% reacted with the soluble antigen; none reacted with fraction 1. This study suggests that these antigens might be adaptable to the detection of human gonococcal antibody, especially in the female.

In vitro susceptibility of Neisseria gonorrhoeae to nine antimicrobial agents.

The in vitro action of nine antibiotics was tested by the agar streak method against 45 gonococcal strains isolated from penicillin-therapy failures. The penicillin susceptibility range of these strains was 0.003 to 1.32 mug/ml, and the tetracycline susceptibility range was 0.125 to 2.0 mug/ml. Minimal inhibitory concentrations of minocycline and doxycycline paralleled the activity of tetracycline and ranged from 0.125 to 1.0 mug/ml and 0.125 to 2.0 mug/ml, respectively. Rifampicin, with a narrow range of 0.5 to 1.0 mug/ml, inhibited 75% of the strains at 0.5 mug/ml. The range for cephaloridine and cephaloglycine was 0.5 to 20.0 mug/ml, but another cephalosporium derivative, cephalexin, exhibited greater activity in its range of 0.25 to 20.0 mug/ml. A semisynthetic penicillin, carbenicillin, with a range of 0.025 to 0.75 mug/ml, displayed more activity against the lower susceptible penicillin G gonococcal strains.

Preparation of cell walls and protoplasm of Neisseria with the Ribi cell fractionator.

The varied pressures required for disruption of Neisseria gonorrhoeae and other species of Neisseria when the Sorvall-Ribi refrigerated cell fractionator is used in the preparation of cell walls and cellular protoplasm are reported. Optimal disruption pressure for the gonococcus was considerably less than that required for other members of the genus Neisseria. Pressures varied from 8,000 psi for N. gonorrhoeae F62, colony type 4, to 22,000 psi for the nonpathogenic Neisseria-N. sicca, N. flava, and N. catarrhalis. Representative electron photomicrographs are shown.

Antigens of Neisseria gonorrhoeae: characterization by gel filtration, complement fixation, and agar-gel diffusion of antigens of gonococcal protoplasm.

With the use of the agar-gel-diffusion and complement-fixation techniques, it was shown that protoplasm from different gonococcal isolates reacted with sera from some humans with a history of gonorrhea but did not react with "normal" human sera. The reactive antigen(s) could be partially separated from the other antigens by passing the gonococcal protoplasm through Sephadex G-200. The antigen(s) reacting in the gel-diffusion and complement-fixation tests appeared in the same fraction. On the basis of Sephadex gel filtration, the molecular weight of this antigen(s) is probably greater than 200,000.