The regulation of NADP-linked isocitrate dehydrogenase in Aspergillus nidulans

The regulation of NADP-linked isocitrate dehydrogenase (NADP-IDH) has been studied in wild-type and mutant strains of Aspergillus nidulans. In the wild-type strain studied, the levels of NADP-IDH vary in a similar way to those of acetamidase, acetyl-CoA synthase, isocitrate lyase and malate synthase under all growth conditions used. Similarly, fac mutants, which are altered in the regulation of these enzymes of acetate utilization, are affected in NADP-IDH levels in a parallel fashion, as are cre mutants, which show altered carbon catabolite repression of this group of enzymes. Possible functions of the NADP-IDH enzyme are considered.

Evidence on the conformation of HeLa-cell 5.8 S rRNA during interaction with 28 S rRNA

The sites and extents of bisulphite-mediated deamination of cytidine residues in HeLa-cell 5.8 S rRNA within the 5.8 S / 28 S rRNA complex have been determined. Comparison of these data with equivalent data for isolated ('unbound') 5.8 S rRNA suggests that the conformation of several cytidine residues, including inter alia those within the 5'- and 3'-terminal sequences, differs in the two forms of 5.8 S rRNA. We therefore conclude that the sequences comprising stem 'a' of the isolated 5.8 S rRNA are involved in hydrogen-bonding to 28 S rRNA in the 60 S ribosomal subunit, but that the interactions are more subtle and complex than those proposed in earlier models.

The regulation of phosphoenolpyruvate carboxykinase and the NADP-linked malic enzyme in Aspergillus nidulans

It has previously been suggested that the synthesis of phosphoenolpyruvate carboxykinase (EC 4.1.1.32) in Aspergillus nidulans is regulated by a repression-derepression mechanism involving a glycolytic intermediate, and not by induction. Results obtained using compounds that enter the tricarboxylic acid cycle via 2-oxoglutarate, and that can supply both a carbon and a nitrogen source for A. nidulans, suggest it is more likely that the synthesis of phosphoenolpyruvate carboxykinase is inducible, and only weakly regulated by carbon catabolite repression. a similar study of the regulation of the NADP-linked malic enzyme (EC 1.1.1.40) indicates that it too may be inducible.

The nucleotide sequence at the 3'-end of Neurospora crassa 25S-rRNA and the location of a 5.8S-rRNA binding site

The sequence of 110 nucleotides adjacent to the 3'-end of Neurospora crassa 25S-rRNA has been derived by chemical sequencing methods. Sequences present between 40 and 85 nucleotides of the 3'-end were found to complement sequences at the 3'- and 5'-ends of 5.8S-rRNA. Interaction was shown to occur between 5.8S-rRNA and a specific 3'-terminal fragment of 85 nucleotides derived from 25S-rRNA. We have also demonstrated that the nucleotide sequence at the 3'-end of N. crassa 5.8S-rRNA (-UCAUUOH) is different from the published sequence (-UUUUOH) which was derived from rDNA.

Chemical modification studies and the secondary structure of HeLa cell 5.8S rRNA

Various secondary structure models have been proposed for 5.8 S rRNA. In this paper HeLa cell 5.8 S rRNA is shown to possess several sites that are reactive to carbodiimide at 25 degrees, and other regions that are unreactive. Previous work has established the distribution of reactive and unreactive cytidine residues along the primary structure (11). The secondary structure model of Nazar et al. (7) is fully compatible with the chemical reactivity data whereas other models are partly incompatible. We conclude that the model of Nazar et al. provides the best approximation so far available to the conformation of isolated 5.8 S rRNA. Findings on the effect temperature on the chemical reactivity of different parts of the structure are summarized. The findings described in this paper should provide a basis for examining the specific interaction of 5.8 S rRNA with 28 s rRNA.

Sex preference in patient selection of a family physician

A Patient Panels Registry was developed to study patient identification with family physicians in a large health maintenance organization. There was a clear correlation between the sex of the patient and the sex of the physician. Female patients were 1.49 times as likely as males to select a female physician. Male patients were 1.14 times as likely as females to select a male physician. Women physicians were found to have panels consisting of 66.4 percent female patients, while panels of the male physicians were 53.8 percent female. In order to interact most effectively with both male and female patients, family physicians must be able to recognize their own sex biases as well as those of their patients.

Evidence on the conformation of HeLa-cell 5.8S ribosomal ribonucleic acid from the reaction of specific cytidine residues with sodium bisulphite

The reaction of HeLa-cell 5.8S rRNA with NaHSO3 under conditions in which exposed cytidine residues are deaminated to uridine was studied. It was possible to estimate the reactivities of most of the 46 cytidine residues in the nucleotide sequence by comparing 'fingerprints' of the bisulphite-treated RNA with those of untreated RNA. The findings were consistent with the main features of the secondary-structure model for mammalian 5.85S rRNA proposed by Nazar, Sitz, & Busch [J. Biol. Chem (1975) 250, 8591--8597]. Five out of six regions that are depicted in the model as single-stranded loops contain cytidine residues that are reactive towards bisulphite at 25 degrees C (the other loop contains no cytidine). The cytidine residue nearest to the 3'-terminus is also reactive. Several cytidines residues that are internally located within proposed double-helical regions show little or no reactivity towards bisulphite, but the cytidine residues of several C.G pairs at the ends of helical regions show some reactivity, and one of the proposed loops appears to contain six nucleotides, rather than the minimum of four suggested by the primary structure. Two cytidine residues that are thought to be 'looped out' by small helix imperfections also show some reactivity.

Changes in serum B hydroxybutyrate concentrations in dairy cows kept under commercial farm conditions

beta hydroxybutyrate (BHB) serum concentrations were measured at regular intervals throughout a lactation in groups of animals from three commercial dairy herds. The period of study covered all the major seasonal management changes. BHB levels changed significantly only when the dietary intake of the cows was altered either in quantity of quality. The changes in concentrations of serum BHB were of particular interest during the two grazing seasons when the deteriorating quality of the pasture was reflected in significantly higher concentrations. It is considered that serum BHB concentrations are worthy of further investigation as a parameter for inclusion in preventive medicine monitoring schemes for commercial dairy herds.

Increased and decreased sensitivity to carbon catabolite repression of enzymes of acetate metabolism in mutants of Aspergillus nidulans

The creA204, creB15 and creC27 mutations have been shown to cause carbon catabolite derepression of acetly CoA synthase and isocitrate lyase in Aspergillus nidulans. A recessive mutation, cre-34, which is linked to the creC gene, results in these enzymes being more sensitive than cre or wildtype strains to catabolite repression. The acetamidase levels of strains containing cre mutations have been investigated and provide support for the hypothesis that an acetate metabolite, rather than acetamide, induces this enzyme.

Pleiotropic mutants of Aspergillus nidulans altered in carbon metabolism

Mutants altered in carbon catabolite regulation have been isolated by selecting for mutants of the areA217 strain capable of using acetamide as the sole nitrogen source in the presence of sucrose. In addition to creA mutants described previously be Arst and Cove, strains with mutations in two new genes, creB and cre C, have been found. The creB and creC mutants grow poorly on some sole carbon sources and have low levels of some enzymes of carbon catabolism e.g. beta-galactosidase and D-quinate dehydrogenase. The creB and creC mutants are hypersensitive to fluoroacetate, fluoroacetamide and allyl alcohol in the presence of glucose or sucrose but not glycerol; and the enzymes, acetamidase and alcohol dehydrogenase, are less sensitive to carbon catabolite repression than the wild-type strain. Extracellular protease and alpha-glucosidase enzyme activities are elevated in creB and creC mutants, while L-proline and L-glutamate uptake capacities are lower in both the presence and absence of glucose. Interactions between creA, B and C mutations have been investigated in double mutants, and the dominance properties of creB and creC mutants determined. The results indicate that the creB and creC genes may have a regulatory role in the control of carbon catabolism.

Reconstruction of the oral cavity after obliterative surgery for cancer

Simple and reliable methods for reconstruction of the oral cavity after obliterative surgery for carcinoma include (1) nasolabial cheek flaps, (2) hemiforehead and total forehead flaps, and (3) temporal island flaps. In general, the nasolabial flap is sufficient for resurfacing areas of the oral cavity anterior to the second molar tooth, while the temporal island flap provides satisfactory coverage posterior to this area. The forehead flap, which is very durable and reliable, is reserved for reconstruction of the more massive defects. Technics and use of each reconstructive procedure are described.

Neuroelectric blocking factors in multiple sclerosis and normal human sera

Serum samples from 13 multiple sclerosis (MS) patients and ten normal human serum samples were applied to cerebral neocortex cultures and evaluated for their ability to block evoked electric activity. A high proportion of sera positive for neuroelectric blocking factors was found in both groups, and there was no substantial difference between serum samples from MS patients and those from normal human volunteers. Some of the neuroelectric blocking factors were thermolabile, others were thermostable, and still others may have been complement-dependent. It is concluded that the ability to block evoked electric responses in tissue cultures is a nonspecific serum property, and that it is not specifically related to the pathogenesis of demyelinating disease.

Early experience with the Boerema button for bleeding oesophageal varices

Early experience with the use of the Boerema button for bleeding oesophageal varices is reported. A simplified technique for its insertion is described, and of the 6 patients so treated, only 1 died. No patient has re-bled in the short follow-up period available, and oesophageal appearances suggest that prolonged relief from bleeding can be anticipated. Further exploration of the button ligation transection technique is suggested not only for control of acute bleeding, but also for patients unsuitable for shunt surgery.

Ultrastructure of mumps virus replication in organotypic cultures of hamster choroid plexus

Organotypic cultures of newborn hamster choroid plexus were inoculated with equal titre doses of newly isolated or hamster adapted strains of mumps virus. The ultrastructure of virus replication in choroid epithelial cells of the cultures was compared. No qualitative differences were observed; however, the adapted strain produced significantly greater numbers of virions and earlier destruction of the cultures. These findings are consistent with previous in vivo observations of the ultrastructure of the replication of these strains in the newborn hamster central nervous system. This in vitro study leads further support to the hypothesis that differences in the in vivo biological effects of the virus strains are primarily the result of virus-cell rather than virus-host interactions.