R(-)2-fluoro-N-n-propylnorapomorphine: a very potent and D2-selective dopamine agonist

A series of 2-substituted N-n-propylnorapomorphine (NPA) derivatives were synthesized and compared with other DA agonists for affinity to D1 and D2 dopamine (DA) receptors in rat brain corpus striatum tissue. The 2-substituents tested reduced D1 affinity similarly, but enhanced D2 affinity in the rank order: F greater than OH greater than Br greater than OCH3 greater than H greater than or equal to NH2. The extraordinarily high D2 affinity (Ki = 12 pM) and D2 vs. D1 selectivity (57,500) of 2-F-NPA far-exceeded that of all other DA agonists tested, and it was about 10-times more potent than NPA in vivo.

A systematic approach towards the complete assignment of 13C resonances for horse ferrocytochrome c

The complete 1H-NMR assignments for horse ferrocytochrome c have been reported by Wand and colleagues and by our group at Oxford. Using these 1H assignments, we now report chemical shift assignment for 205 13C resonances arising from horse ferrocytochrome c. This is from a total of 437 13C nuclei with covalently attached protons. These chemical shift assignments have been achieved using 1H-detected two-dimensional heteronuclear 1H-13C correlation techniques. The data have been collected from samples of horse ferrocytochrome c without isotopic enrichment. The complete 13C assignments for all carbons with covalently linked protons are reported for the amino acids Ala, Thr, Val and Gly. Specific assignments are tabulated for all 49 methyl groups, for 52 of 92 alpha-carbon resonances, for 10 resonances associated with the heme group, for all aromatic side-chain 13C resonances which have covalent protons and give rise to observable cross peaks under the experimental conditions used, as well as for a number of other side chains of aliphatic amino acids.

Characterization of 58-kilodalton human neutrophil collagenase: comparison with human fibroblast collagenase

A series of experiments has been carried out to characterize 58-kDa human neutrophil collagenase (HNC) and compare it with human fibroblast collagenase (HFC). N-Terminal sequencing of latent and spontaneously activated HNC shows that it is a distinct collagenase that is homologous to HFC and other members of the matrix metalloproteinase gene family. Activation occurs autolytically by hydrolysis of an M-L bond at a locus homologous to the Q80-F81-V82-L83 autolytic activation site of HFC. This releases a 16-residue propeptide believed to contain the "cysteine switch" residue required for latency. Polyclonal antibody raised against HNC cross-reacts with HFC but with none of the other major human matrix metalloproteinases examined. Treatment of HNC with endoglycosidase F or N-glycosidase F indicates that it is glycosylated at multiple sites. The deglycosylated latent and spontaneously activated enzymes have molecular weights of approximately 44K and 42K, respectively. Differences in the carbohydrate processing of HFC and HNC may determine why HFC is a secreted protein while HNC is stored in intracellular granules. The kinetic parameters kcat and KM for the hydrolysis of the interstitial collagen types I, II, and III in solution by both collagenases have been determined. The strong preferences of HNC for type I collagen and of HFC for type III collagen found in earlier studies have been confirmed. The preference of HNC for type I over type III collagen is almost abolished when fibrillar collagens are used as substrates, but the preference for HFC for type III over type I collagen is only partially decreased.(ABSTRACT TRUNCATED AT 250 WORDS)

[In vitro transformation induced by carcinogens in rat tracheal epithelial cells]

An in vitro transformation system was established using primary rat tracheal epithelial (RTE) cells cultured in medium with or without feeder layer cells. About 24-48 hours after plating, RTE cells were exposed to N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0-0.6 microgram/ml), benzo (a) pyrene (BaP, 0-20 micrograms/ml), or 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK,0-2.0mg/ml). One or two weeks after exposure, enhanced growth variants (EGV) among the RTE cells were selected in serum containing medium by removing either the feeder layer or bovine pituitary extract (BPE) and epidermal growth factor (EGF). The results showed that EGV transformation was induced by MNNG, BaP and NNK, and a dose dependent EGV transformation was observed in the MNNG and NNK experiments. Our experimental results suggest that for the selection of EGV's from among RTE cells exposed to chemical carcinogens, the use of BPE- and EGF-free medium is more sensitive and convenient than is removing the feeder layers.

Assignment of proton resonances, identification of secondary structural elements, and analysis of backbone chemical shifts for the C102T variant of yeast iso-1-cytochrome c and horse cytochrome c

Resonance assignments for the main-chain, side-chain, exchangeable side chain, and heme protons of the C102T variant of Saccharomyces cerevisiae iso-1-cytochrome c in both oxidation states (with the exception of Gly-83) are reported. (We have also independently assigned horse cytochrome c.) Some additional assignments for the horse protein extend those of Wand and co-workers [Wand, A. J., Di Stefano, D. L., Feng, Y., Roder, H., & Englander, S. W. (1989) Biochemistry 28, 186-194; Feng, Y., Roder, H., Englander, S. W., Wand, A. J., & Di Stefano, D. L. (1989) Biochemistry 28, 195-203]. Qualitative interpretation of nuclear Overhauser enhancement data allows the secondary structure of these two proteins to be described relative to crystal structures. Comparison of the chemical shift of the backbone protons of the C102T variant and horse protein reveals significant differences resulting from amino acid substitution at positions 56 and 57 and further substitutions between residue 60 and residue 69. Although the overall folding of yeast iso-1-cytochrome c and horse cytochrome c is very similar, there can be large differences in chemical shift for structurally equivalent residues. Chemical shift differences of amide protons (and to a lesser extent alpha protons) represent minute changes in hydrogen bonding. Therefore, great care must be taken in the use of differences in chemical shift as evidence for structural changes even between highly homologous proteins.

Presynaptic inhibition of dopamine synthesis in rat striatal tissue by enantiomeric mono- and dihydroxyaporphines

Presynaptic autoreceptor-mediated modulation of dopamine (DA) synthesis was evaluated as the inhibition of tyrosine hydroxylase activity by enantiomeric mono- and dihydroxyaporphines with minced striatal tissue from rat brain. The isomers of N-n-propylnorapomorphine (NPA) both inhibited tyrosine hydroxylase activity [IC50 = 0.3 and 1.0 microM for (R)-(-)- and (S)-(+)-NPA, respectively; R/S potency = 3.6]. Their effects were fully blocked by the nonselective DA receptor antagonist fluphenazine, as well as by the D2-selective antagonist spiperone, but not by the D1 antagonist SCH-23390. These results suggest a D2-type autoreceptor-mediated inhibition of DA synthesis, with limited enantiomeric selectivity of this catechol-aporphine. The corresponding monohydroxy analogs, (R)-(-)- and (S)-(+)-11-hydroxy-N-n-propylnoraporphine (11-OH-NPa) were about 100 times less potent (IC50 = 42 and 87 microM, respectively) than the NPA isomers in fully inhibiting the enzyme activity in normal tissue but, after depletion of endogenous DA by acute in vivo pretreatment with reserpine (which did not alter the number of D1 or D2 specific binding sites), (R)-(-)-11-OH-NPa was a highly potent but partial agonist (IC25 = 7 nM). Fluphenazine and spiperone fully antagonized the inhibition of tyrosine hydroxylase by (R)-(-)-11-OH-NPa in reserpinized tissue, but SCH-23390 was ineffective. Actions mediated by endogenous DA probably contribute to the effect of high concentrations of (R)-(-)-11-Oh-NPa to evoke a full inhibition of DA synthesis, but its high potency partial agonist effects appear to be mediated by D2-autoreceptors. (S)-(+)-11-OH-NPa was a very weak partial agonist in reserpinized tissue, with an IC25 = 30 microM (essentially the same as normal tissue); thus, (R)-(-)-11-OH-NPa was greater than 4,000 times more potent than its S-(+)-enantiomer in the absence of endogenous DA. These results demonstrate that NPA, which contains a catechol moiety, acts as a full agonist to inhibit striatal DA synthesis via a presynaptic autoreceptor of the D2 type, with only slight stereoselectivity, and that its monohydroxy analog is a very potent but partial D2 autoreceptor agonist, with very high stereoselectivity.

[Assay of myelin basic protein (MBP) antibody in the cerebrospinal fluid and serum of rabbits with experimental allergic encephalomyelitis (EAE) before and after sensitization]

The level of MBP antibody in the cerebrospinal fluid (CSF) and serum of 20 rabbits with EAE was determined with ELISA respectively before and after sensitization with MBP. The results showed that after sensitization the level of the antibody in CSF increased in accordance with the degree of severity of the EAE. While the increase of the serum was not parallel while the state of the disease. This study suggested that the determination of the level of MBP antibody might be of help in the diagnosis of demyelinative disease of the central nervous system and in monitoring the course and estimating the prognosis of the disease.

R(-) and S(+) stereoisomers of 11-hydroxy- and 11-methoxy-N-n-propylnoraporphine: central dopaminergic behavioral activity in the rat

R(-)11-Hydroxy-N-n-propylnoraporphine (11-OH-NPa) induced stereotyped behavior in the rat as potently (ED50 = 0.80 mg/kg, i.p.) as R(-)apomorphine (APO) and this effect was blocked by haloperidol; the 11-methoxy congener, R(-)11-MeO-NPa, had a weak effect (ED50 greater than 10 mg/kg) and the S(+) isomers had none. The isomer R(-)11-OH-NPa potentiated locomotion stimulated by apomorphine; S(+)11-OH-NPa inhibited it and the isomers of 11-MeO-NPa were inactive. Catecholaporphines usually are inactive orally, but both R(-) and S(+)11-OH-NPa were similarly potent after oral or parenteral administration. The isomer S(+)11-OH-NPa inhibited spontaneous and apomorphine-induced locomotion (ID50 = 1.8-2.7 mg/kg, p.o. and i.p.) and stereotyped behavior (ID50 = 3 mg/kg, p.o. or i.p.), all without inducing catalepsy. While apomorphine was short-acting (1-2 hr), the effects of R(-)11-OH-NPa persisted up to 6-7 hr and those of the S(+) isomer for at least 2.5 hr; moreover, the efficacy of R(-)11-OH-NPa increased markedly up to 3-4 hr, although its ED50 was independent of time (ED50 = 1.7-1.9 mg/kg, i.p. from 1-3 hr). The total effect of R(-)11-OH-NPa (p.o. or i.p.) over time was more than 10-times greater than that of injected apomorphine. These observations accord with the reported high (nM) affinity of 11-OH-NPa at cerebral DA receptor sites (D2 greater than D1) and weak interactions of the 11-methoxy congener. They support the conclusion that the R(-) and S(+) stereoisomers are neuropharmacologically active, respectively, as DA agonist and apparent antagonist, as was found with the enantiomers of N-n-propylnorapomorphine, perhaps due to the low intrinsic postsynaptic agonist activity of the S(+) isomers. Moreover, 11-OH-NPa was highly bioavailable orally and unusually long-acting; it may be absorbed slowly or have active metabolites. Hydroxy-substitution of aporphines at the 11-position, homologous to the 3-OH of DA, evidently is critical for affinity and activity at the DA receptor. These or other monohydroxyaporphines may represent leads to potentially useful DA agonist or antagonist drugs.

Epithelial modulation of airway smooth muscle

The responsiveness of airway smooth muscle is influenced by the functional integrity of the respiratory epithelium. The nature of this regulatory action by the epithelium remains largely unresolved. Several explanations may account for the epithelium-dependent responses induced by numerous stimuli. This review will present and discuss the evidence suggesting that the epithelium generates an inhibitory signal or signals that function to modulate the responsiveness of the underlying smooth muscle. In addition, the possible candidates for the identity of this epithelium-derived relaxing factor or factors will be assessed. Finally, the mechanisms by which the epithelium-derived relaxing factors may act to modulate bronchomotor tone will be discussed.

[Application of cluster analysis of the study of commodity bulbus Lilii (I)]

Cluster analysis has been applied to the classification of various commodities of Bulbus Lilii in order to sort out the main one. The stomatic index of the commodity has been determined.

[Chemical constituents of Bupleurum Longicaule Wall. ex DC. var. giraldii Wolff]

Five crystalline compounds were isolated from the whole plant of B. longicaule var. giraldii for the first time. Four of them were identified as rutin (I), narcissin (II, quercetin (II) and isorhamnetin (IV) respectively by means of chemical studies and spectrometric analysis.

[Plasma leucine enkephalin and beta-endorphin levels in patients with essential hypertension and the effects of captopril]

To further study the relationship between endogenous opioid peptides and essential hypertension, we measured the concentrations of plasma leucine-enkephalin (LEK) and beta-endorphin (beta-EP) in 50 patients with essential hypertension by radioimmunoassay and investigated the effects of captopril on them. It was shown that the concentrations of plasma LEK and beta-EP in patients with essential hypertension were lower than those in normotensive subjects. No effects of age and sex were found on the concentrations of plasma LEK and beta-EP, and there was no difference in plasma LEK and beta-EP levels between patients with Stage I essential hypertension and those with Stage II essential hypertension. After a single dose of captopril, blood pressure and plasma angiotensin II decreased, plasma renin activity increased; and plasma LEK and beta-EP levels increased. Plasma LEK and beta-EP levels in patients with essential hypertension increased after one month of captopril treatment. In conclusion, the lower plasma LEK and beta-EP levels in patients with essential hypertension indicate that LEK and beta-EP may play a role in the pathogenesis of essential hypertension, and the depressor effects of captopril may act through LEK and beta-EP, besides blocking formation of angiotension II.

[EEG analysis of healthy adults in the highlands of Xining]

An EEG analysis of 400 healthy adults in Xining, Qinghai Province, about 2260 meters above the sea level was made. A comparison of the data with those obtained from a healthy group of adults in the Beijing flatlands was carried out. It was found that (1) the incidence of abnormal EEG of the examinees in Xining was higher (32.25%) than that in Beijing, (2) the index in Xining was lower than that in Beijing, (3) the slow waves occurred more frequently in the Xining group, (4) the spikes were seen in 9.25% of the examined subjects and the sharp waves in 3.0% of the examined subjects in Xining, and (5) the physiological reactions were not so sensitive in the Xining group.

[The biological effect of sodium butyrate (NaBT) on SGC-7901 cells]

Changes of (Na+-K+)-ATPase activity, cAMP and fibronectin (FN) content and cell surface microvilli were studied cytochemically, immunocytochemically and scanning electron microscopically on human stomach Glandular carcinoma (SGC-7901) cells treated with NaBT(2.5 mM). It was found that NaBT not only inhibited cell growth but also remarkably decreased the activity of cell surface (Na+-K+)-ATPase of SGC-7901 cells. Note worthy was that, in comparison with the untreated tumor cells, the increase of the intensity of intracellular cAMP and FN immunofluorescence in NaBT-treated tumor cells was striking. Moreover, in contrast to untreated tumor cells, the cell surface of NaBT-treated tumor cells showed more smooth and fewer microvilli under SEM. That NaBT may induce differentiation of SGC-7901 cells through inhibition of (Na+-K+)-ATPase activity and modulation of cellular cAMP and FN content was discussed.

The effects of multiple amino acid substitutions on the polypeptide backbone of tuna and horse cytochromes c

The cytochromes c provide a wide range of natural and mutant homologous proteins which may be used to study structure/function relationships in biological electron-transfer reactions. A description of the cytochrome c structure has been provided by high-resolution X-ray crystallography for the cytochromes from tuna, bonito, rice and yeast (Saccharomyces iso-1). Correlation of these structures with NMR parameters is necessary to confirm the structure of the protein in solution and to permit the routine characterisation of cytochromes c with novel sequences. We have previously reported a method based on the analysis of pseudocontact shifts which allowed us to compare the conformations of some amino acid side chains of tuna cytochrome c in solution and in the crystalline state. Here we report a comparison of the conformations of the polypeptide backbone of cytochromes c in proteins from tuna and horse, using the chemical shifts of the amide NH and C alpha H protons. It is found that the backbone conformation and hydrogen-bond network is closely conserved between these proteins, despite 19 amino acid substitutions. Appreciable differences occur in two regions, around Asn 31 and at the beginning of the 60s helix. Evidence for some rotational or translational motion of the C-terminal helix is also presented.

[An analytical study of optical conditions of the elderly]

The visual acuity, refraction and related factors in 471 eyes 60-90 years of age were analyzed with the authors's statistical method for refractive data. The mean logarithmic visual acuity (Lv) of all eyes naked was 4.66 (equivalent to 20/44, or 6/13), and with corrections 5.03 (equivalent to 20/18.7, or 6/5.6). There was significant negative linear correlation between Lv and age (r = -0.9684), Lv = 5.7183-0.0095 x age. The percentages of hyperopia and myopia in the series were 47.8% and 39.7%, the mean refraction being +0.96 DS +0.78 DC and -1.29 DS -0.95 DC respectively. The percentage of mixed astigmatism was 7.86%, averaging +0.71 DC -0.74 DC. The mean refraction of all the patients was -0.05 +/- 2.90 DS -0.04 +/- 1.14 DC.