Scoring of nonmetric cranial traits: a methodological approach.

The purpose of the present study was to analyse the replicability of the scoring of discontinuous traits. This was assessed on a sample of 100 skulls from the Frassetto collection (Dipartimento di Biologia Evoluzionistica Sperimentale of Bologna University) analysed through intraobserver comparisons: the discontinuous traits were determined on the same skulls and by the same observer on 3 separate occasions. The scoring was also assessed through interobserver comparisons: 3 different observers performed an independent survey on the same skulls. The results show that there were no significant differences in the discontinuous trait frequencies between the 3 different scorings by the same observer, but there were sometimes significant differences between different observers. Caution should thus be taken in applying the frequencies of these traits to population research. After an indispensable control of material conditions (subject age included), consideration must be given to standardisation procedures between observers, otherwise this may be an additional source of variability in cranial discontinuous trait scoring.

Interaction of the insecticidal crystal protein CryIA from Bacillus thuringiensis with amino acid transport into brush border membranes from Bombyx mori larval midgut.

The activities of three related Bacillus thuringiensis delta-endotoxins, designated CryIA(a), CryIA(b), and CryIA(c), as inhibitors of K(+)-dependent amino acid transport into membrane vesicles prepared from the anterior and posterior portions of Bombyx mori larval midgut were measured. Under experimental conditions similar to those occurring in vivo (membrane potential approximately -100 mV, inside negative; pH 7.2in/8.8out; an inwardly directed K+ gradient) CryIA(a) toxin produced a clear dose-dependent inhibitory effect on leucine uptake by both the anterior and the posterior gut membrane vesicles, giving half-maximal inhibition constants (IC50) of 2.6 +/- 0.3 and 2.1 +/- 0.2 microgram toxin/mg membrane protein, respectively. The other two delta-endotoxins were practically inactive. A dose-dependent inhibition of amino acid transport by CryIA(a) toxin was also observed on the carrier-mediated K(+)-independent component, i.e., the leucine-only form. This result strongly indicates that the activity of the K+/amino acid cotransporter is directly affected after binding of delta-endotoxin to the brush border membrane. When the extravesicular pH was lowered to pH 7.2, the interaction of CryIA(a) toxin with the brush border appeared more complex, as suggested by the Hill coefficient of the dose-response curves higher than 1. In conclusion, our data indicate that (i) CryIA(a) toxin specifically inhibited K+/leucine symport along the length of the midgut; (ii) the interaction between cotransporters and toxin is affected by the pH of the medium; and (iii) the K+/leucine cotransporter or a strictly associated protein may serve as membrane receptor for CryIA(a) delta-endotoxin in the B. mori larval midgut.

A rapid and sensitive in vitro assay for the activity of Bacillus thuringiensis delta-endotoxins.

1. Activated delta-endotoxins from Bacillus thuringiensis strains toxic to lepidopteran larvae inhibit K(+)-dependent accumulation of amino acids into brush border membrane vesicles (BBMV) from the midgut of the susceptible species Bombyx mori. 2. The activated toxins interfere with the K(+)-dependent uptake of histidine into BBMV only if they are effectively active in vivo. 3. To calculate IC50 values (the toxin concentration which determines 50% of the effect), dose-response curves were performed for each toxin. The values obtained correlate well with the LD50 determined by bioassay. 4. This amino acid inhibition test could represent a rapid (3-6 hr, compared to 3-4 days for bioassay) and sensitive method for the screening of larvicidal activity of known or new recombinant delta-endotoxins.

[The advantages of agglutination and precipitation tests used in the serological diagnosis of meningitis due to H. influenza type B]. / Avantajele unor teste de aglutinare si precipitare folosite în diagnosticul serologic al meningitei cu H. influenzae tip B.

During the period January 1985-July 1988, 532 purulent CSF taken from patients with meningitis, aged between 3 weeks and 91 years, were studied by microscopic examination, cultivation and for H. influenzae type B (HITB) also by coagglutination (COA), counterimmunoelectrophoresis (CIE) and double immunodiffusion (DID) in agarose gel. Positive CSFs were taken from the patients aged 1 month-24 years old, of which 76% from children under 5 years old, and 42% from children under one year. 65.9% of the patients were males; the disease was more frequent in the first and last 4 months of the year, with the highest incidence in April. 12 bacterial spectra were found: N. meningitidis--62.97%, Str. pneumoniae--9.77%, H. influenzae type B--8.27%, and also Salmonella, E. coli, Staphylococcus, Klebsiella, Acinetobacter, beta-hemolytic Streptococcus, Alcaligenes, Proteus and Enterobacter in 4.70; the rest of 14.28% had indefinite etiology. H. influenzae was evidenced in CSF by microscopic examination in 3.38%, by cultivation in 3.94%, and the soluble antigen of HITB by COA in 8.27%, by CIE in 8.08% and by DID in 7.33%. The sensibility order of the tests was: COA, CIE, DID, cultivation and microscopic examination. The COA and CIE techniques are recommended for the current use in examination of the purulent CSF due to their simplicity, rapidity, sensibility, specificity and possibility of establishing the diagnosis when the bacteriologic techniques are negative.