左旋四氢巴马汀加强电针对兔大脑皮层牙髓诱发电位的...

Cortical potentials evoked by stimulation of the contralateral tooth-pulp were recorded epidurally from the SI cortex of rabbits anesthetized with urethane and chloralose. It was found that nociceptive components of the evoked potential consisted of P1 and P2 wavelets with a relative stable peak latency of 22.5 +/- 1.2 ms and 66.1 +/- 1.9 ms respectively. Higher intensity of tooth pulp stimulation was required for appearance of P2 than P1. Diazepam, a non-analgesic sedative, reduced P1 but not P2 amplitude. On the contrary, dolantin, an analgesic, suppressed P2 but showed no significant influence on P1. The results suggest that P2, but not P1 might be related to pain. The effects of l-tetrahydropalmatine (1-THP) and electroacupuncture on P2 were observed on 12 animals. The results showed that both iv l-THP 8mg/kg and electroacupuncture brought forth a decrease in P2 amplitude by 40.3 +/- 14% and 59.3 +/- 10% respectively, while electroacupuncture combined with l-THP produce a further decrease in P2 amplitude by 92.8 +/- 7%. Furthermore, the inhibitory periods of P2 amplitude were significantly prolonged after electroacupuncture combined with l-THP. The results indicated that l-THP enhanced the suppression of P2 by electroacupuncture.     

烟青虫人工饲料的研究

本文报道烟青虫Heliothis assulta的一种人工饲料,其主要成分是麦胚、酵母粉、番茄酱和辣椒粉.与自然食料相比,用这种人工饲料饲养的烟青虫生长快、发育整齐、存活率高,得到的蛹大,成虫繁殖力强.饲料中含0.1—0.2%的NaCI对幼虫的生长发育有促进作用.6龄幼虫对该饲料中干物质、能量和氮的同化效率分别是38.5%、43.9%和48.5%.在连续12代饲养期间,幼虫期存活率在57—92%之间,平均76%.     

The effect of methyl lidocaine on lysophospholipid metabolism in hamster heart

An important feature in the remodelling of fatty acyl chains in cellular phospholipids is the acylation of lysophospholipids. Since lysophospholipids are cytolytic at high concentrations, the acylation reaction may provide an alternate pathway for the removal of cellular lysophospholipids. However, the physiological role of the acylation process in the maintenance of lysophospholipid levels in mammalian tissues has not been clearly defined. In this study, methyl lidocaine was found to inhibit both lysophosphatidylcholine:acyl-CoA and lysophosphatidylethanolamine:acyl-CoA acyltransferase activities in the hamster heart, but the drug had no effect on the other lysophospholipid metabolic enzymes. When the heart was perfused with 0.5 mg methyl lidocaine/mL, acyltransferase activities were attenuated, but there was no change in the activities of phospholipase A or lysophospholipase. The levels of the major lysophospholipids in the heart were not altered by methyl lidocaine perfusion. When the hearts were perfused with labelled lysophospholipid in the presence of methyl lidocaine, there was a reduction in the formation of the phospholipid and an increase in the release of the free fatty acid. However, the labelling of lysophospholipid in the heart was not altered by methyl lidocaine. We postulate that the acylation reaction has no direct contribution to the maintenance of the lysophospholipid levels in the heart.     

A refined linkage map for DNA markers around the pericentromeric region of chromosome 10

A refined genetic linkage map for the pericentromeric region of human chromosome 10 has been constructed from data on 12 distinct polymorphic DNA loci as well as the locus for multiple endocrine neoplasia type 2A (MEN 2A), a dominantly inherited cancer syndrome. The map extends from D10S24 (at 10p13-p12.2) to D10S3 (at 10q21-q23) and is about 70 cM long. Overall, higher female than male recombination frequencies were observed for this region, with the most remarkable female excess in the immediate vicinity of the centromere, as previously reported. Most of the DNA markers in this map are highly informative for linkage and the majority of the interlocus intervals are no more than 6 cM apart. Thus this map should provide a fine framework for future efforts in more detailed mapping studies around the centromeric area. A set of ordered cross-overs identified in this work is a valuable resource for rapidly and accurately localizing new DNA clones isolated from the pericentromeric region.     

Hormonal regulation of gonadotropin-releasing hormone receptors and messenger RNA activity in ovine pituitary culture

Previous studies demonstrate that gonadotroph responsiveness to GnRH, GnRH binding, and the apparent number of GnRH receptors are all increased by 17 beta-estradiol (E) or inhibin (IN) in ovine pituitary cultures. Progesterone (P) attenuates these effects. To explore differences between the effects of IN and E on GnRH binding, a detailed time-course study was performed. The results indicate that after 48 h, IN had a greater effect on binding of a GnRH agonist (5-fold increase) than E (3-fold increase), but was slower to act initially. A combined treatment of IN and E gave a partially additive effect at 48 h (6.5-fold increase). The mechanism of receptor regulation in this system is not known, but could involve synthesis, recycling, or modification of GnRH receptors. To investigate the contribution of altered receptor biosynthesis to the regulation of receptor levels, a functional Xenopus oocyte-based assay for GnRH receptor mRNA activity was employed. After 48 h of treatment, IN or E each led to a 7- to 8-fold increase in GnRH receptor mRNA activity. Treatment with both hormones led to a 19-fold increase. The increase in mRNA activity induced by either hormone was greatly attenuated by P. Modulation of GnRH receptor mRNA levels suggests that IN, E, and P regulate responsiveness to GnRH in the ovine pituitary at least in part by altering de novo synthesis of GnRH receptors. The differing time courses of action, as assayed by GnRH binding, and the additivity of effects at the mRNA level suggest that IN and E alter mRNA levels via different mechanisms.     

DXS28 (C7) maps centromeric to DXS68 (L1-4) and DXS67 (B24) by deletion analysis

Complex glycerol kinase deficiency (CGKD) is a contiguous gene syndrome consisting of glycerol kinase deficiency together with Duchenne muscular dystrophy (DMD), congenital adrenal hypoplasia, and/or Aland Island eye disease. Deletion mapping of genomic DNA from patients with CGKD was carried out and allowed definitive ordering of loci DXS28 (C7), DXS68 (L1-4), and DXS67 (B24). Most reports have placed DXS68 centromeric to DXS28 and DXS67 on the basis of the initial mapping of the Iowa patient 3, but others have presented evidence consistent with the placement of DXS28 telomeric to DXS68 and DXS67. Through the use of DNA from CGKD patients with a variety of genomic deletions, this controversy is resolved and the order Xcen...DMD-DXS28-DXS68-DXS67...pter is definitively demonstrated.     

Sex determination in the dioecious Melandrium

Summary Melandrium album (2n=24), a dioecious species with heteromorphic sex chromosomes (XY, males and XX, females), has a strong genetic commitment for sex determination. We report here a procedure for obtaining haploid plants from cultured anthers and show that genotype, pollen stage, cold treatment and certain culture media components are essential for a reproducible yield of embryos. Our procedure increased the number of responsive anthers and not the number of responsive microspores per anther. Most likely, our experimental system allows the recovery of competent microspores, and this on a medium containing either an auxin or a cytokinin. All of the 36 anther-derived plants tested expressed a female phenotypic sex instead of the theoretical one male one female ratio. When analysed cytologically, the plants exhibited the corresponding female genetic sex (one or two X chromosomes).     

Corrected sequence of the mannitol (mtl) operon in Escherichia coli

The previously published sequences of the operator-promoter region of the mannitol operon of Escherichia coli and of the mtlD gene have been found to contain a number of errors. The major conclusions reported previously were correct, but additionally it is now clear that a C-terminal portion of mannitol-1-phosphate dehydrogenase (the mtlD gene product) exhibits significant sequence identity with an amino-terminal region of human liver fructose-6-phosphate-2-kinase:fructose-2,6-bisphosphatase.     

Prolonged blood pressure reduction by orally active renin inhibitor RO 42-5892 in essential hypertension.

OBJECTIVE--To investigate the effects of a novel specific renin inhibitor, RO 42-5892, with high affinity for human renin (Ki = 0.5 x 10(-9) mol/l), on plasma renin activity and angiotensin II concentration and on 24 hour ambulatory blood pressure in essential hypertension. DESIGN--Exploratory study in which active treatment was preceded by placebo. SETTING--Inpatient unit of teaching hospital. PATIENTS--Nine men with uncomplicated essential hypertension who had a normal sodium intake. INTERVENTIONS--Two single intravenous doses of RO 42-5892 (100 and 1,000 micrograms/kg in 10 minutes) given to six patients and one single oral dose (600 mg) given to the three others as well as to three of the patients who also received the two intravenous doses. RESULTS--With both intravenous and oral doses renin activity fell in 10 minutes to undetectably low values, while angiotensin II concentration fell overall by 80-90% with intravenous dosing and by 30-40% after the oral dose. Angiotensin II concentration was back to baseline four hours after the low and six hours after the high intravenous dose and remained low for at least eight hours after the oral dose. Blood pressure fell rapidly both after low and high intravenous doses and after the oral dose and remained low for hours. With the high intravenous dose the daytime (0900-2230), night time (2300-0600), and next morning (0630-0830) systolic blood pressures were significantly (p less than 0.05) lowered by 12.5 (95% confidence interval 5.6 to 19.7), 12.2 (5.4 to 19.3), and 10.7 (3.2 to 18.5) mm Hg respectively, and daytime diastolic pressure was lowered by 9.3 (2.2 to 16.8) mmHg. With the oral dose daytime, night time, and next morning systolic blood pressures were lowered by 10.3 (5.5 to 15.4), 10.5 (4.2 to 17.2), and 9.7 (4.0 to 15.6) mm Hg, and daytime and night time diastolic pressures were lowered by 5.8 (0.9 to 11.0) and 6.0 (0.3-12) mm Hg respectively. CONCLUSIONS--The effect of the inhibitor on blood pressure was maintained over a longer period than its effect on angiotensin II. RO 42-5892 is orally active and has a prolonged antihypertensive effect in patients who did not have sodium depletion. This prolonged effect seems to be independent, at least in part, of the suppression of circulating angiotensin II.