Agglutination reactions of spontaneous canine tumour cells, induced by concanavalin A, demonstrated by an isotopic assay

Quantitative assessment of the agglutination of 51Cr labelled canine cell suspensions to canine kidney cell monolayers has been performed over a range of concanavalin A concentrations. Agglutination was observed with all cell cultures tested, comprising four spontaneous canine melanomas, two canine mammary carcinomas, a benign mammary tumour and a contact-inhibited kidney cell line. The melanomas tested showed strong specific inhibition of concanavalin A agglutination by 10(-2)M alpha-methyl-D-glucopyranoside. Inhibition of agglutination of mammary tumour and kidney cells was weaker and less specific. Agglutination was inhibited at 4degrees C. Reduced agglutination to glutaraldehyde-fixed mono-layers was observed in the case of mammary tumours but was absent when contact-inhibited kidney cells were tested. The specificity of the reaction for transformed cells and the parameters involved are discussed.     

Insanity and adultery: forensic implications of a divorce case

Legal responsibility for acts presumes that a person's behavior is rationally intentional and under voluntary control. Automatism, a type of insanity defense, contends that the person's conscious, voluntary control of behavior has been impaired by a mental disorder. In a recent case in South Carolina, automatism was offered as a defense to adultery, an at-fault grounds to divorce. On appeal, the State Supreme Court recognized the novel application of mental impairment defenses in domestic litigation and remanded the case for rehearing. Implications of the ruling for clinical and forensic practice in family court are discussed.     

Biologic and serologic characterization of the 161A strain of Naegleria fowleri

The 161A strain of Naegleria isolated from the nasal swab of a boy (9) was grown axenically in Nelson's medium. When 10,000 amoebae from the axenic medium were inoculated onto each monkey kidney cell (Vero) culture, characteristic cytopathic effects (CPE) were noticed in 4 to 5 days. The CPE consisted of granulation of the host cell cytoplasm, cell shrinkage, nuclear pycnosis, and discontinuity of cell sheet. When 10,000 amoebae were instilled intranasally into a group of ten 2- to 3-week-old mice, 8 of the 10 mice exhibited characteristic symptoms of primary amoebic meningoencephalitis and died within 10 to 12 days. Histopathology of the brain revealed necrotic tissue and an acute inflammatory reaction in the superficial regions of the brain. In the gel diffusion and immunoelectrophoresis tests the sonically disrupted antigens of 161A amoebae reacted extensively with the hyper-immune sera against 3 strains (CA, CJ, HB-1) of pathogenic N. fowleri and produced patterns very similar to those produced by the homologous systems. Further, anti-HB-1 serum absorbed with the 161A antigens failed to react with the antigens of HB-1, CA, CJ, and 161A strains thus indicating antigenic identity of 161A strain with N. fowleri. In view of these observations it was concluded that the strain 161A is pathogenic and should be reclassified as N. fowleri.     

Establishing generalized verb-noun instruction-following skills in retarded children

Diazotized (125I)-diiodosulfanilic acid (DD125ISA) binds specifically to the exposed proteins on the surface of the rabbit platelet plasma membrane. This was demonstrated by the following observations with the use of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of whole platelets and the isolated plasma membrane fraction: (1) the specific activity of isolated membrane protein was sevenfold that of whole platelet protein, (2) no proteins of intact platelets were labeled which were not represented in the isolated plasma membrane, (3) DD125ISA-labeled proteins were altered by trypsin treatment of intact, labeled platelets, and (4) the pattern of labeling produced by reaction of isolated membranes with DD125ISA differed from that produced by the labeling of intact platelets. Reaction of DD125ISA with intact platelets produced labeling of only the three membrane glycoproteins (molecular weights: 180,000, 125,000, and 92,000 daltons) with greatest labeling of the largest glycoprotein and least labeling of the smallest glycoprotein. When rabbit platelets were labeled simultaneously with DD125ISA and 51Cr, the two isotopes were similarly distributed in various density populations of platelets. Some DD125ISA was solubilized from labeled and washed platelets by sonication, but all platelet DD125ISA was recovered in the plasma membrane fraction after 30 minutes' circulation in vivo. In vivo 51Cr recovery and survival were not altered by simultaneous labeling of platelets with DD125ISA. The disappearance of DD125ISA from circulating platelets (T 1/2 = 17 hours) was more rapid than 51Cr (T 1/2 = 30 hours) and appeared exponential in contrast to the linear 51Cr disappearance. On the other hand, DD125ISA did not disappear from platelets faster than 51Cr when doubly labeled platelets were harvested after 3 hours' circulation and incubated in autologous plasma (T 1/2 of DD125ISA elution = 43 hours, 51Cr = 33 hours). SDS-PAGE analysis of DD125ISA-labeled platelets after 14 to 20 hours' circulation in vivo demonstrated the same pattern of DD125ISA distribution on membrane glycoproteins as on the platelets prior to infusion. We interpret this symmetrical loss of the membrane label to indicate symmetrical loss of membrane proteins, suggesting that the platelet may lose pieces of membrane and not specific surface proteins during circulation. This could occur during reversible adhesion encounters during the process of hemostasis and cause the smaller size and decreased effectiveness of older platelets.     

Inhibition of in vitro replication of the oyster parasite Perkinsus marinus by the natural iron chelators transferrin, lactoferrin, and desferrioxamine

The mammalian iron-binding proteins transferrin and lactoferrin, the bactericidal peptide lactoferricin B, and the bacterial siderophore desferrioxamine were tested for their ability to inhibit the in vitro replication of the oyster parasite Perkinsus marinus. All three chelators were effective in reducing the parasite proliferation in a dose-dependent manner. Lactoferricin B, a peptide of lactoferrin that exhibits bactericidal properties unrelated to iron chelation, had no inhibitory activity on the parasite. When the chelators were partially or completely saturated with the appropriate iron equivalents, their inhibitory effects on the parasite proliferation were diminished or abolished accordingly, confirming that this activity was related to the chelator's capacity for iron sequestration. Our results indicate that the parasite has a strong requirement for soluble iron and its growth rates are correlated with iron availability. We propose that excess iron accumulation in the host Crassostrea virginica promotes parasite proliferation. P. marinus may avoid oxidative damage that would compromise its intracellular survival by exhaustion the host's intracellular selected iron pools required for superoxide and hydroxyl radical production.