White-gray matter differentiation in computed tomography

A numerical analysis has been performed on six regions of interest within the brain for a total of 60 patients. Three areas of white matter and three of gray matter were included. A difference of 7.1 +/- 1.3 Hounsfeld units (HU: 1,000 scale) was found between white and gray matter. For eight patients who were under 15 years of age, the difference was 5.1 +/- 0.6 HU. Contrast injection resulted in a general increase of values, with gray matter showing a greater elevation by 0.5 HU. The numerical evaluation of white and gray matter has proven to be useful in the diagnosis of leukoencephalopathy.

Prevalence of venereal disease in indigent pregnant adolescents

The prevalence of venereal disease in an indigent adolescent maternity population was determined. Of 740 teenagers examined for gonorrhea and syphilis, 2,4% were found to have gonorrhea, whereas 0.6% had primary syphilis. A concomitant study of 740 adult maternity cases at the same hospital revealed a somewhate higher incidence. Some factors in venereal disease prevalence in pregnant teenagers are discussed briefly.

Isolation and characterization of the surface membranes of fast and slow mammalian skeletal muscle

Fast (extensor digitorum longus) and slow (soleus) rat skeletal muscles served as the source for isolation and biochemical comparison of two distinct surface membrane fractions with properties of the sarcolemma and transverse tubular system. Enriched sarcolemmal membrane from soleus demonstrated a lighter density after sucrose density centrifugation. Sialic acid content was 1.5-fold higher in soleus (62 nmol/mg) than extensor (40 nmol/mg). The specific activity of (Na+ + K+ + Mg2+)-ATPase was similar (1.40 and 1.65 micronmol Pi/mg per 5 min) with the soleus enzyme displaying a (1) greater resistance to inhibition by ouabain, and (2) broader ionic ratio (Na+/K+) requirement than extensor enzyme. The polypeptide and phospholipid composition showed no major differences between the two muscle types. The second surface membrane fraction, tentatively identified as transverse tubule, differed in membrane composition. The major polypeptide of extensor was of 95 000 molecular weight whereas for soleus a Mr=28 000 species was dominant. Total phospholipid content of soleus was 1.5-fold greater than extensor due mostly to increased levels of phosphatidylcholine and phosphatidylethanolamine. Endogenous membrane protein kinase for the 28 000 molecular weight polypeptide was found exclusively in this membrane. The reaction conditions were identical for extensor and soleus since both required divalent cations (Ca2+ and Mg2+) and neither was affected by cyclic AMP. Soleus showed a 2-fold higher capacity for phosphate incorporation than extensor. These studies show that surface membrane fractions derived from fast and slow muscles differ in terms of functional and compositional properties. These differences are specific not only for the surface membrane but for the muscle type and may relate to the known physiological differences observed between fast and slow mammalian muscle.

Social influence processes and the outcome of sensitivity training

Prediction were tested as to the persistence of change after sensitivity training. Using concepts derived from kelman, it was predicted that internalizers will show most durable benefit from training, whereas externalizers (compliants and identifiers) will show less. Questionnaire measures were used based on sociometric rankings of influence sources during training. The subjects were 199 professionals of mixed sex and age attending 5-day sensitivity training programs in England. As predicted, at the close of training internalizers did not differ from externalizers on ratings of benefit by self or by other trainees. Trainers rated internalizers higher (p less than .05). Five months later, internalizers were rated higher than externalizers on benefit by self (p less than .01), and there was a trend in the same direction for ratings by others. Between the two testings of externalizers' benefit there were significant decreases for self-benefit rating (p less than .01) and other-benefit rating (p less than .01), whereas internalizers showed no significant decrease. The findings support typological approaches to the study of social influence and underline the need for caution in selecting the criterion measures to be used immediately after sensitivity training.

The gram positive cocci

Recent changes in taxonomy of the gram positive cocci are discussed. Views on these changes and practical methods of differentiating the staphylococci, micrococci, streptococci, and aerococci are presented. Simplified schemes, using acceptable clinical laboratory techniques, are presented that either differentiate or categorize the pathologically important gram positive coccal species.

Separation of phenylalanine transport events by using selective inhibitors, and identification of a specific uncoupler activity in Yersinia pestis

Phenylalanine transport in Yersinia pestis TJW was differentially inhibited by sulfhydryl blocking reagents, uncoupling agents, and respiratory inhibitors. Kinetic studies with potassium cyanide and sodium azide showed that these compounds have no immediate effect on the initial rate of phenylalanine transport, but have an immediate and severe inhibitory effect on the rate of oxygen uptake. Identical studies with p-chloromercuribenzoate (pCMB) and 2,4-dinitrophenol (DNP) showed that these compounds have an instantaneous and total inhibitory effect on phenylalanine transport. DNP stimulated oxygen uptake, and pCMB caused only a sluggish inhibiton of oxygen uptake. pCMB acted as a competitive inhibitor of phenylalanine transport, whereas DNP inhibitied noncompetitively. Arrenius plots of the initial rate of phenylalanine transport in pCMB- and DNP-treated cells showed that DNP alters the transition temperature of the phenylalanine transport system from 17 C for control cells to 12 C. DNP did not inhibit transport when cells were treated at temperatures of 2 to 10 C. PCMB did not alter the normal transition temperature and inhibited phenylalanine transport over a 2 to 30 C temperature range. Efflux induced by both pCMB and DNP were blocked by placing cells at low temperatures (2 to 20 C). Inhibition of adenosine 5'-triphosphate synthesis by DNP did not show any temperature sensitivity as did phenylalanine transport. These data indicate that: (i) respiration is not obligatory for active transport of phenylalanine in Y. pestis TJW; and (ii) pCMB inhibits transport activity by reacting with the sulfhydryl group(s) at the carrier binding site. The data show that the uncoupler, DNP, selectively alters a temperature-dependent property of phenylalanine transport, that is not related to uncoupling activity of DNP , and probably involves membrane lipid alterations.

Aromatic amino acid transport in Yersinia pestis

The uptake and concentration of aromatic amino acids by Yersinia pestis TJW was investigated using endogenously metabolizing cells. Transport activity did not depend on either protein synthesis or exogenously added energy sources such as glucose. Aromatic amino acids remained as the free, unaltered amino acid in the pool fraction. Phenylalanine and tryptophan transport obeyed Michaelis-Menten-like kinetics with apparent Km values of 6 x 10(-7) to 7.5 x 10(-7) and 2 x 10(-6) M, respectively. Tyrosine transport showed biphasic concentration-dependent kinetics that indicated a diffusion-like process above external tyrosine concentrations of 2 x 10(-6) M. Transport of each aromatic amino acid showed different pH and temperature optima. The pH (7.5 TO8) and temperature (27 C) optima for phenylalanine transport were similar to those for growth. Transport of each aromatic amino acid was characterized by Q10 values of approximately 2. Cross inhibition and exchange experiments between the aromatic amino acids and selected aromatic amino acid analogues revealed the existence of three transport systems: (i) tryptophan specific, (ii) phenylalanine specific with limited transport activity for tyrosine and tryptophan, and (iii) general aromatic system with some specificity for tyrosine. Analogue studies also showed that the minimal stereo and structural features for phenylalanine recognition were: (i) the L isomer, (ii) intact alpha amino and carboxy group, and (iii) unsubstituted aromatic ring. Aromatic amino acid transport was differentially inhibited by various sulfhydryl blocking reagents and energy inhibitors. Phenylalanine and tyrosine transport was inhibited by 2,4-dinitrophenol, potassium cyanide, and sodium azide. Phenylalanine transport showed greater sensitivity to inhibition by sulfhydryl blocking reagents, particularly N-ethylmaleimide, than did tyrosine transport. Tryptophan transport was not inhibited by either sulfhydryl reagents or sodium azide. The results on the selective inhibition of aromatic amino acid transport provide additional evidence for multiple transport systems . These results further suggest both specific mechanisms for carrier-mediated active transport and coupling to metabolic energy.

Selected aspects of adolescent postpartum behavior

Contraceptive, educational, and vocational behavior patterns of postpartum adolescents were examined. Eight months after delivery 269 teenage girls who participated in a comprehensive antepartum psycho-social program were mailed follow-up questionnaires. Eighty-three percent of teenage mothers who responded reported using birth control pills as a form of contraception. We found that single girls were more actively involved in vocational and educational training. This and other observations indicate that marital status of teenage participants is important to their postpartum actions.

Evaluation of the pathotec Rapid I-D system for identification of Enterobacteriaceae

The PathoTec Rapid I-D System for identifying Enterobacteriaceae was evaluated with 471 cultures. In 4,910 individual test comparisons, 95.5% of the results agreed, with results of only two test strips, those for esculin hydrolysis and urease production, agreeing with conventional tests in less than 94% of the trials. The PathoTec system exhibited 94.3% accuracy in identifying these cultures in a double-blind study with conventional media and procedures as the alternate system. Two newly developed test strips, for 0-nitrophenyl-beta-D-galactopyranoside and ornithine decarboxylase, were found to be highly reliable.

Evaluation of the Bactrol Disks, a set of quality control cultures

A set of commercially available quality control cultures was evaluated. These cultures were found to be an acceptable alternate to lyophilized or continuously subcultured cultures for a quality control program.

Plasma emission sources in analytical spectroscopy-I

A critical survey of plasma emission sources used in analytical spectroscopy, excluding conventional arc and spark sources, has been made. In Part I the concept of temperature applied to high-temperature excitation sources is considered, as are arc plasma jets. Part II will be concerned with microwave and capacitively coupled sources and in Part III inductively coupled sources will be dealt with. In the last part a comparison will also be made of all the sources reviewed, from the point of view of sensitivity, precision and freedom from matrix effects.

New system for cultivation of Neisseria gonorrhoeae

A modified Thayer-Martin medium, containing 2.0% agar, 0.25% dextrose, and 5.0 mug of trimethoprim per ml was compared to Thayer-Martin medium for growth of stock cultures of Neisseria gonorrhoeae and for isolation of N. gonorrhoeae from clinical specimens. Stock cultures and male urethral cultures grew equally well on both media, but the modified Thayer-Martin medium detected 10% more female patients positive for gonococci. A description is given of the use of a citric acid-sodium bicarbonate tablet for generating carbon dioxide in a sealed plastic bag containing a culture plate. Equivalent results were obtained on duplicate plates of 336 cultures and specimens when this procedure was compared with the standard candle jar extinction method of incubation. The tablet and plastic bag system has the advantages of economy, ease of use, and safety.

r-b Expanders: their use in identifying routinely and unusually reacting members of Enterobacteriaceae

This cooperative study between a large clinical laboratory and a reference laboratory evaluated the performance of the expanded r/b system for identifying Enterobacteriaceae. The 2,200 cultures isolated in the normal hospital routine presented no problem of identification to the r/b system. About 250 "atypical" cultures which were exchanged between the collaborating laboratories were also identified accurately. The expanded r/b system was found to perform as well as most biochemical-physiological identification systems, and when used appropriately was highly satisfactory as a system for identification of Enterobacteriaceae.

Evaluation of the improved Auxotab 1 System for identifying Enterobacteriaceae

The improved Auxotab Enteric 1 System is more accurate in identifying Enterobacteriaceae than is the original product, and results correlate better with those obtained with conventional tests.

Auxotab--a device for identifying enteric bacteria

A multitest system called the Auxotab that uses ten dehydrated reagents on a paper card has been evaluated with 417 known stock cultures of Enterobacteriaceae. In double-blind studies with the Auxotab, 87% of the strains tested were correctly identified. Results of this study indicate that there is a need for modification of the product in regard to ease of handling, time required for use, and accuracy of identification of enteric bacteria.

Evaluation of the redesigned enterotube--a system for the identification of Enterobacteriaceae

The redesigned Enterotube has been evaluated with 414 unknown Enterobacteriaceae cultures from the stock culture collection of the Center for Disease Control. When the Enterotube was used as recommended by the manufacturer, an average of 96.4% of these cultures were correctly identified. Only two groups (Salmonella and Edwardsiella) were identified with less than 90% accuracy (89.2 and 87.5%, respectively). The Enterotube now provides a convenient, rapid, and accurate test system for the identification of typically reacting enteric bacteria.

In-use evaluation of a commercially available set of quality control cultures

Increasing awareness of the need for a uniform quality control program prompted an evaluation of a commercially available set (Bact-Chek) of eight organisms. A protocol was designed in which this set of control cultures was tested simultaneously in the clinical microbiology laboratory of a 400-bed hospital (the Berkshire Medical Center) and in the reference laboratories of the Bacteriology Section of the Center for Disease Control. The results indicate that the Bact-Chek organisms are essentially as advertised: they constitute a basic set of cultures for a quality control program in clinical microbiology. Ninety per cent of the media and reagents (excluding mycobacterial media and reagents) in the clinical laboratory were checked with this set of eight cultures. Additional cultures not in the set were used to check the remaining 10% of the media and reagents.

API system: a multitube micromethod for identification of Enterobacteriaceae

The API system for identification of Enterobacteriaceae was evaluated with 366 cultures. Overall accuracy of identification was 96.4%; of the 13 cultures misidentified, 7 were atypical strains.