Post-operative analgesia following thoracotomy in the dog: an evaluation of the effects of bupivacaine intercostal nerve block and nalbuphine on respiratory function.

Pain following thoracotomy reduces pulmonary ventilation in man and a similar effect is believed to occur in animals. The effects of two analgesic regimens on arterial blood gas parameters were studied in dogs following thoracotomy. Post-Operative analgesia was provided with intermittent nalbuphine, either alone or in combination with an intercostal nerve block using bupivacaine. Arterial blood gas analysis was carried out at 4, 8 and 16 h post-operatively, both before the administration of nalbuphine and again 30 min later. Animals which received nalbuphine alone had a significant rise in arterial oxygenation following administration of this analgesic. This effect was not observed at 4 and 8 h post-operatively in dogs which had an intercostal block with bupivacaine, but was seen at 16 h post-operatively when it could be anticipated that the effects of bupivacaine would have waned. These results suggest that intercostal block with bupivacaine can provide analgesia for over 8 h, and that the duration of action of nalbuphine in controlling post-operative pain in the dog is probably less than 4 h.

Cystine-rich type II antifreeze protein precursor is initiated from the third AUG codon of its mRNA.

The primary translation product encoded by sea raven antifreeze protein mRNA was labeled during cell-free synthesis with [3H]leucine. N-terminal sequencing of the immunoselected translation product showed that the third AUG in the mRNA is used as the initiating methionine codon. The antifreeze protein precursor is therefore 163 amino acids long. Amino acid analysis and sequencing of the deblocked N-terminal peptide from the mature circulating form of the antifreeze indicated that glutamine at position 35 is the N-terminal residue. The most likely site of signal peptide cleavage is after alanine at position 17, suggesting that the sea raven antifreeze protein is produced as a preproprotein. Analysis of slot blots indicates that the gene for the antifreeze protein is present in 12-15 copies in the sea raven genome. A representative gene copy was sequenced. It is split into six exons spanning 2.2 kilobase pairs and, based on composite maps of genomic clones, is not accompanied by a second copy within at least 25 kilobase pairs of flanking DNA. The transcription start site was determined by primer extension. Ninety base pairs upstream from this point, beyond the CAAT and TATA boxes, is a putative cis-acting regulatory element in the form of a triplicated 21-base pair tandem repeat.

Wolffish antifreeze protein genes are primarily organized as tandem repeats that each contain two genes in inverted orientation.

The antifreeze protein genes of the wolffish (Anarhichas lupus) constitute a large multigene family of 80 to 85 copies, which can be classified into two sets. One-third of the genes were linked but irregularly spaced. The other two-thirds were organized as 8-kilobase-pair (kbp) tandem direct repeats that each contained two genes in inverted orientation; DNA sequence analysis suggests that both genes are functional. Except for a single region specific to each gene, the genes and their immediate flanking sequences were 99.2% identical. This degree of identity ended soon after a putative transcription termination sequence; as the 3' ends of the genes were only 1.3 kbp apart, these sequences might confer mutual protection from interference by transcriptional runoff. A Southern blot of wolffish DNA restricted with enzymes that do not cut within the tandem repeats indicated that the repeats were clustered in groups of six or more. The organization of antifreeze protein genes in the wolffish was very similar to that in the unrelated winter flounder, which produces a completely different antifreeze. This similarity might reflect common dynamics by which their progenitors adapted to life in ice-laden sea water.

Multiple genes provide the basis for antifreeze protein diversity and dosage in the ocean pout, Macrozoarces americanus.

The ocean pout (Macrozoarces americanus) produces a set of antifreeze proteins that depresses the freezing point of its blood by binding to, and inhibiting the growth of, ice crystals. The amino acid sequences of all the major components of the ocean pout antifreeze proteins, including the immunologically distinct QAE component, have been derived by Edman degradation. In addition, sequences of several minor components were deduced from DNA sequencing of cDNA and genomic clones. Fifty percent of the amino acids are perfectly conserved in all these proteins as well as in two homologous sequences from the distantly related wolffish. Several of the conserved residues are threonines and asparagines, amino acids that have been implicated in ice binding in the structurally unrelated antifreeze protein of the righteye flounders. Aside from minor differences in post-translational modifications, heterogeneity in antifreeze protein components stems from amino acid differences encoded by multiple genes. Based on genomic Southern blots and library cloning statistics there are 150 copies of the 0.7-kilobase-long antifreeze protein gene in the Newfoundland ocean pout, the majority of which are closely linked but irregularly spaced. A more southerly population of ocean pout from New Brunswick in which the circulating antifreeze protein levels are considerably lower has approximately one-quater as many antifreeze protein genes. Thus, there appears to be a correlation between gene dosage and antifreeze protein levels, and hence the ability to survive in ice-laden seawater. Southern blot comparison of the two populations indicates that the differences in gene dosage were not generated by a simple set of deletions/duplications. They are more likely to be the result of differential amplification.

Homoeosis in Drosophila: the ultrabithorax larval syndrome.

Recent results [Morata, G. & Kerridge, S. (1981) Nature (London) 290, 778-781] have shown that early Ultrabithorax- clones transform the posterior compartments of the adult meso- and metathoracic legs to prothorax. These transformations have not been seen in Ultrabithorax homozygous larvae, which are reported to show only transformations of the metathorax and the first abdominal segment to mesothorax [Lewis, E. B. (1978) Nature (London) 276, 565-570]. However, as the ventral surface of the larva does not exhibit sufficient markers to distinguish the posterior regions of these segments, cryptic larval transformations similar to those in the adult have been suggested (by Morata and Kerridge). We have further examined larvae of wild-type and various Ultrabithorax mutant genotypes, with particular attention to the dorsal surface. We find that Ultrabithorax homozygous larvae exhibit dorsal abnormalities consistent with transformations of the anterior metathorax and anterior first abdominal segment to mesothorax and of the posterior meso- and metathorax to prothorax as predicted by Morata and Kerridge; however, the posterior of the first abdominal segment remains untransformed. We suggest that in both larvae and adults the posterior first abdominal segment remains untransformed by Ultrabithorax mutations and that the unit of development with regard to the proximal bithorax complex consists of adjoining posterior and anterior compartments from neighboring segments rather than of segments themselves.