A non-T: Non-B cell bears I-A,I-E,I-J,and Tla (Qa-1?) determinants

A non-T:non-B accessory cell in peritoneal washout or spleen-cell suspensions facilitates T-cell proliferative responses to the mitogen, concanavalin A. Utilizing monoclonal antibody, we show that this accessory cell bears the same I-A- and I-E-subregion controlled determinants as found on B cells. In addition, the same accessory cell bears a Tla (Qa-1?)-region and an I-J-subregion controlled determinant. This I-J determinant is also present on splenic accessory cells involved in in vitro antibody responses to sheep red blood cells. Data in a companion paper show that not all anti-I-J sera contain antibody reactive with the accessory cell, and suggest that T cells involved in the generation of suppressor activity and accessory cells bear different I-J-subregion controlled determinants.     

Sidedness of membrane structures in Rhodopseudomonas sphaeroides. Electrochemical titration of the spectrum changes of carotenoid in spheroplasts,spheroplast membrane vesicles and chromatophores

The shift of the carotenoid absorption spectrum induced by illumination and valinomycin-K⁺ addition was investigated in membrane structures with different characteristics and opposite sidednesses isolated from Rhodopseudomonas sphaeroides. Right-side-out membrane structures were prepared by isotonic lysozyme-EDTA treatment of the cells (spheroplasts) and by hypotonic treatment of spheroplasts (spheroplast membrane vesicles). Inside-out membrane structures (“chromatophores”) were obtained by treating spheroplast membrane vesicles by French press or sonication.The membrane structures with either sidedness showed the same light-induced change of the “red shift” type. However, the absorbance change by K⁺ addition in the presence of valinomycin in the right-side-out membrane structures were opposite to that in the inverted vesicles, “blue shift” in the former and “red shift” in the latter. The carotenoid absorbance change was linear to membrane potential, calculated from the concentration of KCl added, with a reference on the cytoplasmic side, through positive and negative ranges.     

Metronidazole-induced susceptibility of adult mice to intestinalClostridium botulinum colonization

Clostridium botulinum type A spore challenges were given orogastrically to adult mice that had been treated with metronidazole. The organism multiplied in the intestinal tract for up to five days if it was administered 9–48 h after the last dose of metronidazole. The known antibacterial spectrum of metronidazole indicated that obligate anaerobic bacteria are important in the natural resistance of adult mice to colonization byC. botulinum, but treatment with the antimicrobial agent did not reduce the number of these bacteria in the cecum and colon.     

Effects of an inhibitor of glucosylceramide synthase on glycosphingolipid synthesis and neurite outgrowth in murine neuroblastoma cell lines.

1-Phenyl-2-decanolyamino-3-morpholino-1-propanol (PDMP), an effective inhibitor of UDP-glucose:ceramide glucosyltransferase, caused inhibition of cell growth in murine neuroblastoma cell lines. Metabolic labeling of glycosphingolipids with [14C]galactose in NS-20Y, Neuro2a, and N1E-115 cells showed reduced incorporation of radioactivity into gangliosides and neutral glycosphingolipids when threo-PDMP was present in the medium. Treatment of NS-20Y cells with threo-PDMP resulted in a time-dependent decrease in mass levels of gangliosides and neutral glycosphingolipids. After 24 h in the presence of 50 microM threo-PDMP, neutral glycosphingolipid mass was reduced to 32%, where glucosylceramide was the most affected (90% decrease). The ganglioside mass was reduced to 57% of the original content. Neurite outgrowth from neuroblastoma cells in serum-free medium was significantly inhibited by threo-PDMP in a dose-dependent manner. Threo-PDMP also caused retraction of neurites which had been induced to extend in serum-free medium. Pretreatment of cells with GM1 partially restored the ability of NS-20Y cells for neurite outgrowth in the medium containing threo-PDMP. These results suggest a possible role for glycosphingolipids in neurite outgrowth of murine neuroblastoma cells.     

Ejaculations induced by p-chloroamphetamine (PCA) in rats, hamsters and mice.

The ejaculatory response induced by p-chloroamphetamine (PCA) in male rats, hamsters and mice was observed during 2 hours after the injection. The animals were treated intraperitoneally with PCA at doses ranging from 0.78125 to 160 mg/kg. The ED50 (effective dose in 50% of animals) values of PCA for the initiation of ejaculation in rats and hamsters were 1.3397 (1.0732-1.6725) and 0.1105 (0.0802-0.1522) mg/kg, respectively. On the other hand, no ejaculation was observed in any mice at any doses examined. So we concluded that there are species differences in the ejaculatory response, induced by PCA, among rats, hamsters and mice.     

Pre- and post-implantation losses of embryos in aging female IVCS mice

Mated female mice of the IVCS strain, aged 90 (control group), 180, 210, 240, 270, 300, 330, 360 and 420 days old, were studied for pre- and post-implantation loss of embryos. The percentage of pre-implantation loss in mice aged 90 to 210 days was 1.7/11.8 (14.4%) to 2.7/11.7 (23.1%). In mice aged 240 to 300 days it increased significantly as compared to the controls (46.5-90.2% versus 14.4%). It reached 100% in 300-days-old mice. The post-implantation loss of embryos and/or fetuses in mice aged 90 to 240 days was 1.0/10.2 (9.8%) to 2.5/9.0 (27.8%). In mice aged 270 to 300 days it increased significantly compared to the controls (100% versus 9.8%). The decrease in reproductive activity appeared first in a decrease in litter size, followed by a decrease in the number of blastocyst and implantation sites, and finally by anovulation during the process of aging in IVCS mice.     

Central effects of yohimbine on copulatory behavior in aged male rats

It is well known that yohimbine has a history of popular use because of its supposed aphrodisiac properties. The present study was done to determine whether yohimbine can modify the copulatory behavior of aged male rats. Adult male rats of the Wistar-Imamichi strain, 52 weeks of age and weighing 600-650g, were injected intracerebroventricularly with yohimbine hydrochloride (5, 10 micrograms/10 microliters/rat) or vehicle. Each male was then given the opportunity to mate with a receptive female for 30 min after administration of yohimbine or vehicle. Yohimbine produced significant decreases in the latency to initial mounting and significant increases in the number of mountings. However, there was no ejaculation in the yohimbine-and vehicle-treated males. This study is the first to clearly establish an important modulator of sexual arousal for yohimbine in aged male rats.