The mixed kidney cell-lymphocyte reaction in rats

Optimal conditions for obtaining the proliverative response in mixed kidney cell-lymphocyte culture (MKLC) have been determined in rats. The addition of 2-mercaptoethanol to the culture medium was essential for successful stimulation of lymphocytes by allogeneic kidney cells. Proliferative responses by standard MLC and MKLC were compared in rats with the same or a different Ag-B locus. In most strain combinations, there was a significant correlation between MLC and MKLC reactions, However, the DA-ACI combination, compatible at the Ag-B locus, consistently showed negative MLC and positive MKLC reactions. This suggested the possibility that this technique allowed the expression of kidney specific antigens.     

Transnasal hypophysectomy

A transnasal trans-sphenoidal surgical approach to the pituitary gland is described. The operative and post-operative experiences with the use of this technique on 21 patients with hormone-dependent malignant disease are reported. In 2 patients the procedure was abandoned because of intrasellar haemorrhage and in 1 an empty sella was found. Fifteen patients developed diabetes insipidus and 1 patient died in the postoperative period.     

Biogenesis of cellulolytic enzymes by Trichoderma ligorum on media with "inductor"

Identical distribution of C2- and Cx-cellulase activities of enzyme complexes produced by Trichoderma lignorum on a medium with lactose, a soluble "inductor", and on a medium with cellulose was found by means of disc elestrophoresis in polyacrylamide gel. The maximum rate of synthesis of cellulases on the medium with lactose was registered during the highest deceleration, and even complete cessation, of the fungal growth. During this phase, only one electrophoretically homogeneous cellulase component with Rf of 0.44 possessing all types of the cellulase activity is present in the cultural broth. In the course of growth of the fungus on cellulose after 48 hours, also only one electrophoretically homogeneous component with Rf of 0.44 was found in the cultural broth when the rate of the substrate degradation was highest. The appearance of minor protein components with the activity of cellulase at later stages of cultivation after cessation of the fungal growth is supposed to be caused by modification of the main cellulase component with Rf of 0.44 by the growth medium.     

Response plasticity in hamster olfactory bulb: peripheral and central processes

It is a well-established fact that prolonged odor stimulation leads to marked sensory adaptation. This study demonstrates comparable electrophysiological phenomena occurring at the level of the olfactory receptor and at more central olfactory structures. Recordings of overall receptor response and of olfactory bulb unit responses were made during repeated odor stimulation. During the course of a single, continuous odor presentation response decrements were seen in the EOG (at the olfactory receptors) and were mirrored at the mitral cell layer of the bulb. When brief periods without stimulation were introduced between such odor presentations, receptor responsiveness rebounded to its original level, but mitral cell responses did not. On the basis of this dissociation it is suggested that the pattern of response decrement within the bulb represents a case of stimulus-specific habituation in a simple cortical subsystem and is well worth future investigation as a model of neural plasticity. Surgical disconnection of the olfactory bulb from one or more of its centrifugal inputs results in hyperactive, hyperresponsive mitral cells, which habituate more rapidly and show longer recovery times than do those in the intact bulb. In addition, the synchronization of such units to the inhalation cycle is markedly reduced as compared with normal preparations. These facts together suggest that the habituation of mitral cell activity does not depend on centrifugal inputs, although one or more of such inputs act indirectly in an inhibitory fashion to modulate and tune mitral cell response characteristics.     

A comparative study of several methods for recording spontaneous motor activity in mice under drug effects

Various existing methods of recording motor activity in animals are briefly reviewed. An electronic adaptation of an old one, the Jiggle cage, is described. The relative advantages and demerits in recording behaviour of mice under drug effects are compared with those of the traditional Jiggle cage, an electromagnetic activity counter and observational ratings.     

The human serum paraoxonase/arylesterase gene (PON1) is one member of a multigene family

A physiological role for paraoxonase (PON1) is still uncertain, but it catalyzes the hydrolysis of toxic organophosphates. Evidence that the human genome contains two PON1-like genes, designated PON2 and PON3, is presented here. Human PON1 and PON2 each have nine exons, and the exon/intron junctions occur at equivalent positions. PON1 and PON2 genes are both on chromosome 7 in human and on chromosome 6 in the mouse. Turkey and chicken, like most birds, lack paraoxonase activity and are very susceptible to organophosphates. However, they have a PON-like gene with approximately 70% identity with human PON1, PON2, and PON3. Another unexpected finding is that the deduced amino acid sequences of PON2 in human, mouse, dog, turkey, and chicken and of human PON3 are all missing the amino acid residue 105, which is lysine in human PON1. The expanded number of PON genes will have important implications for future experiments designed to discover the individual functions, catalytic properties, and physiological roles of the paraoxonases.     

Fission yeast pak1+ encodes a protein kinase that interacts with Cdc42p and is involved in the control of cell polarity and mating

A STE20/p65pak homolog was isolated from fission yeast by PCR. The pak1+ gene encodes a 72 kDa protein containing a putative p21-binding domain near its amino-terminus and a serine/threonine kinase domain near its carboxyl-terminus. The Pak1 protein autophosphorylates on serine residues and preferentially binds to activated Cdc42p both in vitro and in vivo. This binding is mediated through the p21 binding domain on Pak1p and the effector domain on Cdc42p. Overexpression of an inactive mutant form of pak1 gives rise to cells with markedly abnormal shape with mislocalized actin staining. Pak1 overexpression does not, however, suppress lethality associated with cdc42-null cells or the morphologic defeat caused by overexpression of mutant cdc42 alleles. Gene disruption of pak1+ establishes that, like cdc42+, pak1+ function is required for cell viability. In budding yeast, pak1+ expression restores mating function to STE20-null cells and, in fission yeast, overexpression of an inactive form of Pak inhibits mating. These results indicate that the Pak1 protein is likely to be an effector for Cdc42p or a related GTPase, and suggest that Pak1p is involved in the maintenance of cell polarity and in mating.