Anti-HBs antibody. A new immunoenzymatic detection. Preliminary results (author's transl)]

The detection of anti-HBs antibody has been carried out using a new technique where a system for the detection of HBs antigen in the solid phase is adopted to demonstrate the presence of anti HBs antibody by inhibition of the immunoenzymatic reaction. The sensitivity of the method has been compared: with that of passive haemagglutination and with that of radioimmunoassay in liquid phase, for human serum obtained from 10 chronic antibody carriers and also serum from 1 rabbit, with that of solid phase radioimmunoassay for 91 positives serums. The method appears: in the range of sensitivity of passive haemagglutination and radioimmunoassay in the liquid phase, less sensitive than that of solid phase radioimmunoassay, far superior to that of electrosyneresis.     

C3 binds with similar efficiency to Fab and Fc regions of IgG immune aggregates

The covalent binding reaction of the third component of complement (C3) with rabbit IgG immune aggregates has been studied by enzymic digestion of C3b-IgG adducts. In these adducts C3b was radioactively labeled in the free thiol group generated during activation of the internal thioester of C3. Trypsin digestion of ¹⁴C-labeled C3b-IgG adducts degrades C3b to a small antibody-bound ¹⁴C-labeled C3 fragment (¹⁴C-C3frg), whereas the antibody remains unaltered. Papain digestion of trypsin-treated ¹⁴C-C3frg-IgG complexes generated Fc and Fab fragments bearing equivalent amounts of covalently bound ¹⁴C-C3frg (43% and 40%, of the total C3 present in the aggregates, respectively). Hydroxylamine treatment of the ¹⁴C-C3frg-Fab and ¹⁴C-C3frg-Fc complexes released a ¹⁴C-C3frg of similar size (about 3–4 kDa) in which the N-terminal residue was the radiolabeled Cys¹⁰¹⁰. A fragment with the same radioactive N terminus and characteristics was obtained by sequential trypsin and papain digestion of purified C3 labeled with iodo–[¹⁴C] acetamide. Affinity-purified ¹⁴C-C3frg-Fc complexes digested with pepsin generated a mixture of radioactive peptides, most probably complexes formed by ¹⁴C-C3frg and Cγ2 or the hinge digestion products, and ¹⁴C-C3frg-pFc' complexes. The latter was also immunoprecipitated with anti-Fc-Sepharose from the pepsin digestion supernatants of ¹⁴C-labeled-C3b-IgG complexes. Taken together these data indicate that, during complement activation through the alternative pathway by IgG immune aggregates, C3 is not bound to a single site on the antibody molecule. Both Fab and Fc regions of IgG are equally efficient targets for C3 anchorage. In addition, the data confirm the pFc' as a region of C3 attachment within the Fc portion, and strongly suggest that C3b is bound either to the Cγ2 domain or the hinge or both.     

Performance of six culture media for isolation ofSalmonella species from stool samples

The relative performance of five plating media [Rambach agar; salmonella-shigella (SS) agar, novobiocin-brilliant green-glycerol-lactose (NBGL), modified semisolid Rappaport-Vassiliadis medium (MSRV), andSalmonella Detection and Identification-2 (SM2)] and selenite broth (SB) subcultured in SS agar in the recovery ofSalmonella spp. from 500 human stool specimens was evaluated. On Rambach agar and SS agar, the C₈-esterase test was also used for selection of suspicious colonies. Eighty-one samples were positive for salmonellae on at least one of the six media. Sensitivities and specificities of MSRV, SB, NBGL, SS, Rambach agar, and SM2 were 95.1 and 98.1%, 87.6 and 99.8%, 79 and 91.9%, 69.1 and 99.3%, 56.8 and 96.9%, and 54.3 and 92.4%, respectively. There were statistically significant differences between MSRV and NBGL, Rambach agar, SS agar, and SM2 (p < 0.005), between SB and SS agar, Rambach agar, and SM2 (p < 0.05), and between NBGL and SM2 and Rambach agar (p < 0.005). The greatest number of isolates was recovered with MSRV, whose performance surpassed that of enrichment in selenite broth, probably because the subcultures were not repeated on MSRV. This hypothesis is now under investigation. The specificity of each of the five solid media was greater than 90%.     

Electric activity in the neocortex of freely moving young and aged rats

Electroencephalographic activity of the neocortex was evaluated in young (5-7 months) and aged (26-28 months) rats. All animals in the aged group showed behavioral impairment in a spatial task (water maze). A neocortical electroencephalogram was derived simultaneously from 16 different neocortical locations and was subjected to spectral analysis. The frequency of occurrence and duration of high-voltage spindles was determined in two sessions, each involving a total of 30 min alert immobility. Changes in spectral characteristics and high-voltage spindles in response to scopolamine administration were also evaluated. The power of high-frequency activity (8-20 Hz) was significantly reduced in the aged subjects. This was greatest in the temporo-occipital regions, while no significant changes were seen in the mediofrontal region. Scopolamine resulted in a large power increase in all frequency bands, but the increase in the higher-frequency range (8-20 Hz) was significantly less in the aged group. The incidence of high-voltage spindles was 6 times higher and their total duration was 9 times longer in aged rats, with virtually no overlap with the young group. In young rats, scopolamine increased the incidence and total duration of high-voltage spindles, while it decreased both parameters in the aged subjects. Cholinergic neurons in the nucleus basalis appeared shrunken in the aged animals. These findings demonstrate that reliable electroencephalographic changes are present in the neocortex of the aged rat, and that some of the physiological alterations may be due to the pathological changes in the cholinergic nucleus basalis.     

α6 integrins participate in pro-T cell homing to the thymus

During embryogenesis, colonization of the thymic rudiment by hemopoietic progenitor cells depends on the adhesion of these cells to the jugular endothelium. Previously, we showed that progenitor T cells (pro-T cells) interact with α₆ integrins present on vascular endothelium. Here, we demonstrate that anti-α₆ integrin antibodies reduced the number of thymocytes up to 80 % in a congenic mouse model for thymus colonization by pro-T cells. In organotypic thymus cultures, the anti-α₆ integrin antibodies did not influence T cell development and proliferation. From this, we conclude that α₆ integrin participates in thymus homing. During mouse thymus ontogeny, α₆ integrin mRNA and protein expression was found as early as day 10 of development; at day 11, perithymic endothelial cells were α₆ integrin positive. Two α₆ integrin mRNA exist which are produced by alternative exon usage. The longer form, α₆, integrin, predominates during early embryonic stages, while the shorter α_6A form was present later during development. Although α₆, integrins can be displayed by immature thymocytes, strongest expression was found on intra- and perithymic vascular endothelium. These data suggest that α₆ integrins are involved in the homing of pro-T cells to the developing thymus by mediating adhesion of pro-T cells to the vascular endothelium.     

Apoptosis in breast carcinoma

Apoptosis may play a major role in determining tumor growth and aggressiveness. The aim of this study was to examine the relationship between apoptosis, expression of bcl-2 and p53 proteins, proliferation index, and other clinicopathological features of breast carcinoma. Sixty-five formalin-fixed paraffin-embedded tissue sections from invasive ductal breast carcinomas were studied for the presence of apoptosis by the terminaldeoxynucleotidyl-transferase-mediated dUTP-FITC nick end-labeling (TUNEL) method. Immunohistochemical methods were also used to determine the expression of estrogen receptor, Ki67, bcl-2 and p53 proteins. The number of apoptotic cells ranged from 2.0 to 236.0/10HPF (mean 36.26, median 28.0). The observation of 30 apoptotic cells/10HPF was more common in tumors > 3 cm, of histological grade III, with a high mitotic index, Ki67 index > or = 300, and p53 positivity; however, statistical significance was found only for the histological grade. Grade I and III tumors displayed an inverse association between the apoptotic index and bcl-2 and p53 protein expressions; grade I tumors frequently expressed bcl-2 (19/28), lacked p53 (20/28), and presented a low number of apoptotic cells (18/28), whereas grade III tumors tended to express p53 (12/17), lacked bcl-2 (13/17), and displayed a high number of apoptotic cells/10HPF (12/17). Multivariate analysis for survival revealed that estrogen receptors and apoptosis were independent variables. These data suggest that apoptosis, rather than proliferation index or expression of bcl-2 or p53 proteins, is an independent factor for the prognosis of survival.     

The orientation of horizontal cell dendrites in the superior colliculus of the hamster: an analysis based on three-dimensional reconstruction of intracellularly injected neurons

Summary We have employed intracellular injection of horseradish peroxidase (HRP) and 3-dimensional, computer-assisted reconstruction to delineate the organization of the dendrites of horizontal cells in the superficial laminae (the stratum griseum superficiale-SGS, and stratum opticum-SO) of the hamster's superior colliculus. Fifteen well-filled cells were analyzed. The dendrites of these cells were generally parallel to the frontal plane. An average of 74.8±13.0% of the total dendritic arbor of the recovered horizontal cells was located within 30° of this plane. The long axis of horizontal cell dendritic trees deviated an average (mean ± s.d.) of 21.7±13.2° from the frontal plane and the average extent of the dendritic tree in this plane was 637±216 m. This differed significantly from the average dendritic extent in the rostrocaudal axis (358±146 m, p<0.001). In some cases, portions of the dendritic arbors of horizontal cells appeared to be oriented along lines of isoelevation or isoazimuth of the visual field representation in the superficial laminae. For other cells, there was no clear relationship between dendritic orientation and the visual field map.     

Silent ovulation in rhesus monkeys (M. mulatta): dissociation of hormonal and behavioral states

Ovarian hormone levels were monitored in rhesus monkeys during the breeding and non-breeding seasons. Ovulation (as inferred from progesterone levels in blood serum in excess of 1.5 ng/ml) was most frequent in the breeding season but was absent only during the month of August. Summer (non-breeding season) ovulations were more frequently "silent," or without heterosexual behavior, than were winter ovulations. This finding suggested that estradiol stimulation may cause different behavioral responses at different times of the year. To test this hypothesis, ovariectomized females were treated with subcutaneously implanted estradiol capsules at different times within and outside the normal breeding season. In either season, treatment with estradiol resulted in increased female-to-female sexual behavior. Only during the breeding season, however, did the estradiol-treated ovariectomized females interact sexually with males. Although males copulated with both estradiol-treated and gonadally intact, untreated females during the breeding season, their rate of copulation with the intact females was higher. The results suggest that: (1) Some female rhesus monkeys displaying strictly seasonal breeding behavior continue to have luteal activity indicative of ovulation in May, June and July, (2) Summer ovulatory cycles are rarely accompanied by sexual behavior, (3) Estradiol treatment of ovariectomized females induces female-to-female sexual behavior both in the breeding and non-breeding seasons, and (4) Males are less responsive to the presence of estrogen-stimulated females in the non-breeding season than in the breeding season.