Simulation of chaotic EEG patterns with a dynamic model of the olfactory system

The main parts of the central olfactory system are the bulb (OB), anterior nucleus (AON), and prepyriform cortex (PC). Each part consists of a mass of excitatory or inhibitory neurons that is modelled in its noninteractive state by a 2nd order ordinary differential equation (ODE) having a static nonlinearity. The model is called a KO_e or a KO_t set respectively; it is evaluated in the open loop state under deep anesthesia. Interactions in waking states are represented by coupled KO sets, respectivelyKI _e (mutual excitation) andKI _i (mutual inhibition). The coupledKI _e andKI _i sets form aKII set, which suffices to represent the dynamics of theOB, AON, andPC separately. The coupling of these three structures by both excitatory and inhibitory feedback loops forms aKIII set. The solutions to this high-dimensional system ofODEs suffice to simulate the chaotic patterns of the EEG, including the normal low-level background activity, the high-level relatively coherent bursts of oscillation that accompany reception of input to the bulb, and a degenerate state of an epileptic seizure determined by a toroidal chaotic attractor. An example is given of the Ruelle-Takens-Newhouse route to chaos in the olfactory system. Due to the simplicity and generality of the elements of the model and their interconnections, the model can serve as the starting point for other neural systems that generate deterministic chaotic activity.Supported by a grant MH06686 from the National Institute of Mental Health     

Transforming mutant v-mos protein kinases that are deficient in in vitro autophosphorylation.

We investigated the importance of specific serine residues for autophosphorylation and transformation by serine-threonine protein kinase p37mos. When either serine 326 or 358 was replaced with alanine, the resulting mutant protein retained the ability to transform NIH 3T3 cells but failed to autophosphorylate in vitro. These studies represent the first functional uncoupling of these two activities for p37mos.     

Identification of a novel metabolite in phenanthrene metabolism by the fungus Cunninghamella elegans

The metabolism of phenanthrene by the fungus Cunninghamella elegans was investigated. Kinetic experiments using [9-14C]phenanthrene showed that after 72 h, 53% of the total radioactivity was associated with a glucoside conjugate of 1-hydroxyphenanthrene (phenanthrene 1-O-beta-glucose). This metabolite was isolated by reversed-phase high-performance liquid chromatography and characterized by the application of UV absorption, 1H nuclear magnetic resonance, and mass spectral techniques. The results show that aromatic ring oxidation followed by glucosylation is a predominant pathway in the metabolism of the polycyclic aromatic hydrocarbon phenanthrene by C. elegans.     

Comparison of a new inorganic membrane filter (Anopore) with a track-etched polycarbonate membrane filter (Nuclepore) for direct counting of bacteria.

Bacterial counts obtained by using a new Anopore inorganic membrane filter were 21 to 33% higher than those obtained by using a Nuclepore polycarbonate membrane filter. In addition, the inorganic filter had higher flow rates, permitting lower vacuum pressures to be used, while the intrinsically flat, rigid surface resulted in easier focusing and sharp definition of bacteria across the whole field of view.     

Cytogenetic analysis of 400 sperm from three translocation heterozygotes

Summary Sperm chromosome complements were studied in three men who carried reciprocal translocations. A total of 400 sperm were karyotyped after in vitro penetration of hamster eggs: 217 sperm from t(2;9) (q21;p22), 164 from t(4;6) (q28;p23) and 19 from t(7;14) (q21;q13). All possible 22 and 31 meiotic segregations were observed for t(2;9) and t(4;6); for t(7;14) only 22 segregations were observed. For alternate segregations, the number of normal sperm was not significantly different from the number of sperm carrying a balanced form of the translocation in any of the translocations, as theoretically expected. The percentage of sperm with an unbalanced form of the translocation was 57% for t(2;9), 54% for t(4;6) and 47% for t(7;14). There was no evidence for an interchromosomal effect in any of the translocations since the frequencies of numerical abnormalities (unrelated to the translocation) were within the normal range of control donors. The frequencies of X- and Y-bearing sperm did not differ significantly from 50%. Results from a total of 17 reciprocal translocations studied by sperm chromosomal analysis were reviewed.     

Regulation of gene expression in rat prostate by androgen and beta-adrenergic receptor pathways

Denervation of rat ventral prostate has been accomplished by excising prostatic tissue fragments and implanting them under the renal capsules of intact syngeneic rats. This resulted in a substantial reduction of expression of a major organ-specific secretory protein, prostatic binding protein (PBP). The depressed level of PBP and its subunits and mRNAs could be restored, however, to as much as 80% of control levels by the administration of a pharmacological dose of exogenous androgen, testosterone propionate (TP), and/or a beta-adrenergic agonist, isoproterenol (ISO). Furthermore, compared to ascorbate-treated controls, TP and ISO increased the synthesis of total cellular protein and PBP by the prostatic renal implants. TP and/or ISO also remodelled the luminal epithelial structure and elevated secretory functions. ISO alone had no effect, however, in castrated animals, indicating that androgen plays a dominant role in the restoration of tissue PBP content. Concomitant to increased PBP content and remodelling of prostatic histomorphology, androgen was also found to raise the depressed levels of beta 2-adrenergic and androgen receptors in the prostatic isografts maintained in intact hosts. In contrast, although an established rat prostatic epithelial cell line (NbE-1) contains high affinity androgen receptor, androgen failed to restore beta-adrenergic receptor as well as PBP content in this cultured cell line. These results, taken together, suggest that a tight coupling between androgen receptor and beta 2-adrenergic receptor pathways may be a prerequisite for PBP expression and functional differentiation in the rat ventral prostate gland.     

Continuous non-aerated Δ1-dehydrogenation of hydrocortisone by PAAH-bead entrapped Arthrobacter simplex

Summary A continuous non-aerated process for the ¹ of hydrocortisone by gel-entrapped Arthrobacter simplex was developed. The process employs PAAH-bead entrapped cells for the continuous conversion of up to 1.6 g/l hydrocortisone solutions in cosolvent containing buffer. Employing ethyleneglycol (10–20% (v/v)) as the cosolvent of choice and menadione sodium bisulfite as effective, non-toxic, sole electron acceptor, efficient non-aerated continuous production of prednisolone in a packed bed conlumn could be maintained, at least for the 30–40 day period of continuous operation tested. The high operational stability observed was made possible by the combined effect of immobilization technique (PAAH bead entrapment), wisely selected cosolvent and artificial electron acceptor, and elimination of aeration and vigorous mixing.     

Should colonoscopy be the first investigation for colonic disease?

Many patients with suspected colonic disease undergo rigid sigmoidoscopy, barium enema examination, and ultimately total colonoscopy, but the need for preliminary radiology has not been formally assessed. A total of 168 patients requiring large bowel investigation were therefore randomised to undergo either rigid sigmoidoscopy plus double contrast barium enema examination or total colonoscopy. Disease was found in 56 patients, including 14 with a carcinoma, 11 with polyps, and 16 with inflammatory bowel disease, the remainder having diverticular disease alone. Of the 89 patients allocated to double contrast barium enema examination, nine required a subsequent colonoscopy for suspected tumour or polyps, three because of incomplete radiological examination, and 12 for rectal bleeding for which no cause was found at the radiological examination. In 16 patients this yielded further information or altered treatment. Of the 79 patients undergoing total colonoscopy, only six required subsequent radiology.As both procedures were well tolerated with no major complications total colonoscopy may be the preferred initial investigation where facilities allow.     

Isolation and mapping of polymorphic cosmid clones used for sublocalization of the multiple endocrine neoplasia type 1 (MEN1) locus

Summary Multiple endocrine neoplasia type 1 (MEN1) is characterized by neoplasia of the parathyroids, the pancreas, and the pituitary. Tumorigenesis involves unmasking of a recessive mutation at the MEN1 locus, which has been mapped to the centromeric part of chromosomal region 11q. In order to localize the MEN1 gene further and to make its isolation possible, a number of new markers were isolated. Two radiation-reduced somatic cell hybrids were identified that only contained markers close to and flanking the MEN1 region. DNA from these hybrids was used for the construction of a cosmid library, and clones containing human inserts were isolated. In addition, cosmid clones were isolated for locus expansion of 7 other markers that were mapped to the 11q12–13.2 region. The 33 newly isolated clones together with 25 previously published markers from this region were analyzed in a panel of radiation-reduced somatic cell hybrids. From the hybridization pattern, the region was divided into 11 parts. New restriction fragment length polymorphisms were identified in 7 of the newly isolated cosmid clones and in one plasmid. These were then used to sublocalize meiotic cross-overs more precisely in two MEN1 families, thus refining the mapping of the disease gene.