Morphine mydriasis in mice.

In mice, morphine produces dose-dependent mydriasis. The mydriatic effect does not depend upon the integrity of the sympathetic system, and interference with central catecholamines or serotonin also does not abolish the response. Ro 4-1284, a neurotransmitter depletor, causes miosis and inhibits completely the response to morphine. This effect may possibly be related to depletion of histamine, GABA, or other neurotransmitter.     

Effects of propranolol and pindolol on platelet aggregation and serotonin release

The aggregation of human platelets by adrenaline and adenosine di-phosphate (ADP) and its inhibition by β-blockers was studied by measuring the light transmission of plateletrich plasma (PRP) and suspensions of washed platelets exposed to these agents. Inhibition of aggregation of PRP and washed platelets was dose related in the two β-blockers tested: propranolol and pindolol. The potent β-blockers pindolol was less inhibitory than propranolol when adrenaline and ADP were used to induce platelet aggregation. The aggregation of platelets by adrenaline has two phases. With low doses of the blockers only the second phase was inhibited whereas higher doses blocked both phases. Preincubation of human platelets (PRP and washed platelets) with both blockers per se resulted in release of ¹⁴C-labelled serotonin. Propranolol released more serotonin than pindolol. There was no concomitant release of lactic dehydrogenase. It is concluded that the effects of propranolol and pindolol on platelets do not correlate with the β-blocking activity of these agents. Rather, the more lypophilic agent, propranolol, is more active both in inhibition of aggregation and in releasing platelet serotonin. It is suggested that these actions of the drugs are related to their non-specific membrane effects.     

An efficient code searching for sequence homology and DNA duplication

This paper presents a very simple and efficient algorithm that searches for sequence homology and gene duplication. The code finds the best alignment of two, short or long, sequences without having to specify how many unmatched bases are allowed to be looped out. Following Needleman & Wunsch (1970), Sellers (1974), Sankoff (1972) and Smith, Waterman & Fitch (1981) gap constraints are incorporated into the program and may be employed. The availability of such a fast computer code enables detection of homologous genes which may fulfill a different function at present, but have arisen from a common gene-ancestor. The code is extremely fast and runs in O(n3/2) units of time. It was applied to the phi X174 sequence.     

Structural and combinatorial constraints on base pairing in large nucleotide sequences

In this paper we discuss the constraints and combinatorial problems of folding long RNA and single stranded DNA molecules into base paired structures. A computer code FOLD-A was designed to perform base pairing foldings of very long sequence chains and search for low energy configurations. The logic of the FOLD-A algorithm is described in some detail. The applications of FOLD-A to the A-protein gene of MS2 and the whole genome of the phi X 174 phage with over 5300 bases are discussed in the accompanying paper.     

Folding of two large nucleotide chains

We have already described the FOLD-A code designed for folding mRNA's and single stranded DNA molecules (Nussinov & Pieczenik, 1984). In this paper we describe its application to two long polynucleotide chains: the A protein gene of the MS2 RNA and the whole genome of the phi X 174 phage. The folded form of the single stranded DNA of the phi X 174 is a six armed star with the origin of replication in its center.     

The synthesis of oxalate from hydroxypyruvate by isolated perfused rat liver the mechanism of hyperoxaluria in L-lyceric aciduria

Hydroxypyruvate and glycolate inhibited the oxidation of [U-¹⁴C]glyoxylate to [¹⁴C]oxalate in isolated perfused rat liver, but stimulated total oxalate and glycolate synthesis. [¹⁴C]Oxalate synthesis from [¹⁴C]glycine similarly inhibited by hydroxypyruvate, but conversion of [¹⁴C₁]glycolate to [⁴C]oxalate was increased three-fold. Pyruvate had no effect on the synthesis of [¹⁴C]oxalate or total oxalate. The inhibition studies suggest that hydroxypyruvate is a precursor of glycolate and oxalate and that the conversion of glycolate to oxalate does not involve free glyoxylate as an intermediate. [¹⁴C₃]Hydroxypyruvate, but not [¹⁴C₁]hydroxypyruvate, was oxidized to [¹⁴C]oxalate in isolated perfused rat liver. Isotope dilution studies indicate the major pathway involves the decarboxylation of hydroxypyruvate forming glycolaldehyde which is subsequently oxidized to oxalate via glycolate. The oxidation of serine to oxalate appears to proceed predominantly via hydroxypyruvate rather than glycine or ethanolamine. The hyperoxaluria of L-glyceric aciduria, primary hyperoxaluria type II, is induced by the oxidation of the hydroxypyruvate, which accumulates because of the deficiency of D-glyceric dehydrogenase, to oxalate.     

Regulation of lipogenesis in adipose tissue: the significance of the activation of pyruvate dehydrogenase by insulin

Simultaneous measurements were made of lipogenesis and pyruvate dehydrogenase activity in segments of rat epididymal adipose tissue incubated with saturating amounts of [U-¹⁴C]glucose and insulin. Glucose was converted to fatty acids at a rate only 64–79% of that permitted by the tissue's content of the active form of pyruvate dehydrogenase (PDH_a). Addition of either of the electron acceptors, phenazine methosulfate (10 μm) or N,N,N′,N′-tetramethyl-p-phenylenediamine (50 μm), increased lipogenesis until it equalled the PDH_a activity of the tissue. Pyruvate release was increased 2-fold or more by the electron acceptors, suggesting that the increase in lipogenesis might have resulted from an increase in the intracellular pyruvate levels such that PDH_a became saturated with substrate. Higher levels of the electron acceptors decreased PDH_a activity, and reduced lipogenesis correspondingly. The data suggest that the maximal rate of lipogenesis in the presence of glucose and insulin is limited by the inability of the tissue to elevate pyruvate levels sufficiently to saturate PDH_a. Although glycerol release was increased by either electron acceptor and insulin partially overcame this effect, the effects of the electron acceptors on PDH_a activity could not be attributed to an increase in lipolysis.     

The role of plastoquinone and β-carotene in the primary reaction of plant Photosystem II

Extraction of Triton Photosystem II chloroplast fragments with 0.2% methanol in hexane for 3 h results in the removal of 90 to 95% of the plastoquinone in the original preparation. The extracted fragments (chlorophyll : plastoquinone ratio, 900 : 1) showed no P-680 photooxidation at 15 K after a single laser flash. The extracted fragments also showed no light-induced C-550 absorbance change at 77 K. Reconstitution of the primary reaction of Photosystem II, as evidenced by restoration of low-temperature photooxidation of P-680, could be obtained by the addition of plastoquinone A but not by the addition of β-carotene. The addition of β-carotene plus plastoquinone A restored the C-550 absorbance change. These results indicate that plastoquinone functions as the primary electron acceptor of Photosystem II and that β-carotene does not play a direct role in the primary photochemistry but is required for the C-550 absorbance change.     

Target size analysis of serotonin 5-HT1 and 5-HT2 receptors in bovine brain membranes

Freeze-dried crude synaptic membranes prepared from bovine cerebral cortex and striatum were exposed to high energy gamma ray from the source of 60Co. The size of serotonin 5-HT1 receptors labeled by [3H]serotonin and that of 5-HT2 receptors labeled by [3H]spiperone or [3H]ketanserin was determined by target size analyses. The values were 57,000 daltons, 145,000 daltons and 152,000 daltons for the cerebral cortex and 56,000 daltons, 141,000 daltons and 150,000 daltons for the striatum, respectively. The estimated sizes were deduced by reference to enzyme standards with known molecular masses and which were irradiated in parallel. Our results demonstrate that the molecular entities in situ for 5-HT1 receptors are distinct from those for 5-HT2 receptors, thus supporting data on the existence of two distinct populations of serotonin receptors, hitherto evidenced physiopharmacologically.     

Effects of the umuC36 mutation on ultraviolet-radiation-induced base-change and frameshift mutations in Escherichia coli

The effects of the umuC36 mutation on the induction of base-change and frameshift mutations were studied. An active umuC gene was necessary in either the uvr⁺ or uvr^? strains of Escherichia coli K12 for UV- and X-ray-induced mutations to His⁺, ColE^R and Spc^R, which are presumably base-change mutations, but it was not essential for ethyl methanesulphonate or N-methyl-N′-nitro-N-nitrosoguanidine-induced His⁺ mutations. In contrast, only 1 out of 13 trp^? frameshift mutations examined was UV reversible, and the process of mutagenesis was umuC⁺-dependent, whereas a potent frameshift mutagen, ICR191, effectively induced Trp⁺ mutations in most of the strains regardless of the umu⁺ or umuC genetic background. These results suggest that base substitutions are a major mutational type derived from the umuC⁺-dependent pathway of error-prone repair.     

Fatty acid and complex lipid composition of a Saccharomyces cerevisiae mutant unable to synthesize delta-aminolevulinic acid.

The lipid composition of a Saccharomyces cerevisiae mutant (GL 1–38) lacking δ-aminolevulinic acid synthase (EC 2.3.1.37) was investigated. This mutant is unable to synthesize heme compounds and, as a consequence, cannot make unsaturated fatty acids or ergosterol. The mutant cells were grown (i) in medium supplemented with δ-aminolevulinic acid or (ii) in medium supplemented with Tween 80 (as a source of oleate) and ergosterol. After growth in the presence of δ-aminolevulinic acid, the fatty acid composition of total lipids and mitochondrial lipids was the same as that of the corresponding wild-type strain. After growth in the presence of Tween 80 and ergosterol, the mutant cells contained increased levels of oleate and greatly decreased levels of palmitoleate. The ratio of unsaturated to saturated fatty acids in these cells was still close to that of the wild type but much lower than that of the medium. The sphingolipids accounted for 5.2% of the lipid phosphate in the wild type and, after growth in Tween 80 and ergosterol, for 12.7% in the mutant. Changes in other phospholipids were too small to be considered significant.     

Role of transmethylation in the elicitation of an oxidative burst in macrophages

Elicited guinea pig peritoneal macrophages (MPs) respond by an oxidative burst (OB) to a variety of membrane stimulants. Evidence has recently accumulated, indicating that phospholipase A₂ activation resulting in unsaturated fatty acid liberation is a prerequisite for the induction of an OB by some stimulants. We examined the effect of inhibiting adenosylmethionine-dependent phospholipid methylation on the capacity of MPs to produce superoxide (O₂^?) in response to membrane stimulation. We found that preincubation of MPs with the transmethylation inhibitor, 3-deazaadenosine (DZAdo), totally eliminated the induction of an OB by concanavalin A, wheat germ agglutinin, and N-formyl-l-methionyl-l-leucyl-l-phenylalanine and partially blocked O₂^? production in response to NaF, phospholipase C, digitonin, the ionophore A23187, and phorbol myristate acetate (PMA). The PMA-elicited OB was the most resistant to inhibition by DZAdo. Homocysteine thiolactone enhanced the blocking effect of DZAdo. These findings suggest that stimulated O₂^? production by guinea pig peritoneal MPs requires enzymatic methylation of an unknown substrate, most likely a membrane phospholipid.     

An easy and rapid method for the measurement of [γ-32P]ATP specific radioactivity in tissue extracts obtained from in vitro rat heart preparations labeled with 32Pi

A rapid method for the measurement of [γ-³²P]ATP specific radioactivity in tissue extracts containing other ³²P-labeled compounds is described. The neutralized acid extract is incubated with cyclic AMP-dependent protein kinase, cyclic AMP and casein. The incorporation of ³²P into casein from [γ-³²P]ATP is measured by perchloric acid precipitation of the protein on filter paper. ³²P-Casein formation is linearly related to the specific radioactivity of the [γ-³²P]ATP. Separation of ATP from other ³²P-labeled compounds is not required for the assay. Application of this method in the evaluation of [γ-³²P]ATP specific radioactivity in two rat cardiac muscle preparations exposed to ³²P_i is demonstrated.     

Measurement of gamma-aminobutyric acid (GABA) in blood.

Blood GABA levels can be readily determined using a radioreceptor assay or gas chromatography-mass spectrometry. After withdrawal of blood, GABA levels remain stable with 25–50% of the GABA in whole blood found in the plasma fraction. Whole blood GABA concentrations range from 500 pmoles/ml to 1200 pmoles/ml in 8 mammalian species with human values being about 900 pmoles/ml. $\text{in vivo}$ administration of aminooxyacetic acid increases both blood and brain GABA levels to a similar extent.     

A study of Sertoli-spermatid tubulobulbar complexes in selected mammals

Tubulobulbar complexes (TBCs) were found in nine mammalian species (opossum, vole, guinea-pig, mouse, hamster, rabbit, dog, monkey and human) primarily originating from the plasma membrane overlying the acrosome of late spermatids. Fewer complexes (4–10) were noted in these species than has been previously reported for the rat (up to 24). TBCs were not seen emanating from round spermatids or those elongated spermatids located within the deep recesses of the Sertoli cell, but they appeared as the spermatids came to reside much closer to the tubular lumen in preparation for release. TBCs developed in areas deficient or lacking in Sertoli filaments and endoplasmic reticulum (ectoplasmic specialization). In general their structural configuration was similar to that shown in the rat, although minor differences were noted. Fine fibrils were observed connecting the distal portion of the spermatid tube with the Sertoli plasma membrane forming a bristle-coated pit. The length of TBCs from most species studied was 1–2 μm, whereas those of the opossum extended 6–8 μm into an apical Sertoli process. TBCs were degraded within the Sertoli cell by its lysosomes prior to sperm release, and for most species there was evidence indicating that formation of more than one generation of TBCs occurred. As sperm release approached, TBCs formed preferentially from the leading edge of spermatids with spatulate heads. The Sertoli cell gradually withdrew from around the spermatid head until only the tip of the head was embedded within the Sertoli cell. This region of contact frequently demonstrated TBCs. The proposed functions of TBCs are reviewed and discussed in light of these findings from other species.     

Diurnal variation in the feeding pattern of rabbits

Laboratory rabbits maintained under controlled lighting and fed $\text{ad libitum}$ exhibit a weak but consistent diurnal fluctuation in feed intake. There are two major periods of eating; at the beginning and the end of the light period. This results in similar feed consumption for the light and dark periods. Water intake shows a similar diurnal variation to that of feed intake. If the normal lighting cycle is retarded by 6 hours, the animals adjust their diurnal rhythm of feeding behaviour to the new lighting cycle within 8 to 15 days. Comparative studies on rats are included.     

Frequency and intensity of chick distress calls: Effects on maternal foodcalling in chickens

The food call of broody domestic hens was used to measure maternal response to four frequency components found in chick distress calls (2,3,4 and 5 kHz) and to variations in distress call intensity (0—86 dB). Foodcalling increased significantly with frequency of the pure-tone test pulse; response to a taped distress call occurred between 40 dB and 86 dB intensity with a maximum at 60–65 dB. The results suggest that the mother uses the higher frequency components in recognizing the distress call, but responds maximally within a specific intensity range. The selective advantage of such behaviour is discussed.     

Depressed T-cell reactivity and suppressor activity of lymphoid cells from cyclophosphamide-treated mice

A study was made of the in vitro proliferative activity of thymus-derived lymphoid cells from cyclophosphamide-treated mice (Cy-mice) and the relationship between this and some in vivo immunological responses. The proliferative response to phytohaemagglutinin (PHA) and allogeneic cells was depressed for up to 3 weeks after drug treatment in spleen and lymph node cells, responsiveness recovering more rapidly in lymph node cells. Cell concentration in culture was shown to be important in such measurements as cells from some Cy-mice were able to inhibit their own proliferation and that of normal lymph node cells. No stable soluble factor responsible for this effect could be isolated. It was shown that in vitro proliferative activity is not a good indicator of in vivo T-cell capability as indicated by the very rapid recovery of ability to reject skin grafts and the fairly rapid recovery of ability to produce cytotoxic cells compared to the slower recovery of in vitro T-cell activities.     

Aspirin and exercise-induced asthma

In four subjects with exercise-induced asthma, aspirin and placebo were administered prior to exercise in a double blind study. Pulmonary function tests did not reveal any difference between the response after aspirin or placebo. We conclude that in these four subjects aspirin did not prevent the bronchoconstrictor response. This might suggest that prostaglandins have no significant role in exercise-induced asthma.