[Effect of endothelin on rat mesenteric microvessels]

By video microscope, it was observed that endothelin (ET) caused constriction of the mesenteric microvessels of pentobarbital-anesthetized Wistar rats in a dose-dependent manner. With the consequence of causing a decrease of rate of blood flow and even some microcirculation disorder, the action was long lasting. The constrictive effect of ET on microvessel was much stronger than norepinephrine. The results suggest that ET is a potent vasoconstrictor for microvessel and may play an important role in causing microcirculatory disorder.

Effect of FK-506 on heart allograft survival in the highly sensitized recipient rats as compared with ciclosporin and 15-deoxyspergualin

The effect of FK-506 on allograft survival in unsensitized recipients has been established in several animal experimental models. In this present study, we investigated the immunosuppressive capacity of FK-506, in comparison with ciclosporin (Cs) and 15-deoxyspergualin (DSG), on heart allograft in presensitized rats. Heart grafts from male ACI rats were heterotopically transplanted to male LEW rats. All recipient rats were sensitized with donor-type whole blood admixed with immunoadjuvant (adjuvant complete Freund) 7 days prior to transplantation. FK-506, Cs and DSG were administered from day 0 to day 14 posttransplantation. The results showed that both FK-506 and Cs significantly prolonged heart allograft survival of presensitized recipients in a dose-dependent manner. The minimum effective dose in the treatment was less for FK-506 than for Cs. However, DSG showed almost no effect of prolongation in this experiment.

In vitro immunosuppressive effect: a comparative study between deoxymethylspergualin and cyclosporin A, on human lymphocyte responses

The immunosuppressive mechanism of Deoxymethylspergualin (MeDSG) on human lymphocyte responses in vitro was assessed in comparison with Cyclosporin A (CyA). Peripheral blood mononuclear cells from normal human volunteers were used for assay of mixed lymphocyte reaction (MLR), cell-mediated lympholysis (CML) and blastogenesis by PHA and OKT3. MeDSG suppressed only allogenic stimulation (MLR and CML), however, CyA showed a suppressive effect for all assays. Kinetic study of MLR showed that the suppressive activity did not decrease even when MeDSG was added at day 3 or day 4. CyA, however, showed a weak suppressive effect when added at a later phase of MLR. The results suggest that MeDSG is a useful immunosuppressive agent and, in vitro, its immunosuppressive mechanism on human lymphocyte responses is quite different from CyA.

The carriage of Escherichia coli resistant to antimicrobial agents by healthy children in Boston, in Caracas, Venezuela, and in Qin Pu, China

BACKGROUND AND METHODS

The healthy members of a community represent its largest reservoir of bacteria resistant to antimicrobial agents. We compared the resistance to eight agents of Escherichia coli in stool samples from untreated, healthy children in cities on three continents.

RESULTS

When screened by a selective method that detected 1 resistant colony in 10,000 colonies, nearly half the children in Boston (18 of 39) had no resistant colonies--a finding consistent with the findings of other surveys performed in developed countries. However, all but 1 of 41 children screened in Caracas, Venezuela, and all but 2 of 53 in Qin Pu, China, carried resistant strains. Only 1 child in Boston but 25 in Caracas and 34 in Qin Pu carried strains resistant to trimethoprim. None of the children in Boston or Caracas but 17 in Qin Pu carried strains resistant to gentamicin. Among 10 colonies selected randomly from each stool sample, the average frequency of resistance in Caracas was 3.6 times greater than in Boston, and that in Qin Pu was 5.3 times greater. There was resistance to five or more antimicrobial agents in 20 percent of the Qin Pu strains and in 6 percent of the Caracas strains but in none of the Boston strains.

CONCLUSIONS

In addition to clinical isolates, as reported previously, the bacteria that colonize health children in the community may be resistant far more often in some regions than in others. A low rate of carriage of antimicrobial resistance in the community should become a public health goal.

Contractile properties of bronchial smooth muscle with and without cartilage

The majority of in vitro studies on airway smooth muscle have used the trachealis (TSM) as a convenient substitute for muscle from airways that constitute the flow-limiting segment. The latter are technically difficult to work with. However, because the site of maximum resistance to airflow is at the third to seventh generations of the bronchial tree, the trachealis preparation is of limited value. Length-tension and force-velocity properties were therefore studied at optimal length (lo) of canine bronchial smooth muscle (BSM) from which cartilage had been carefully removed. Normalized maximum isometric tension or stress (Po x 10(4) N/m2) for BSM was 7.1 +/- 0.19 (SE), which was similar to that of BSM with cartilage (BSM+C, 6.8 +/- 0.21) but lower than for TSM (18.2 +/- 0.81). At length greater than lo, the BSM+C was stiffer than the BSM. The values of maximum shortening capacity (delta Lmax), obtained directly from isotonic shortening at a load equal to the resting tension at lo, were 0.76 lo +/- 0.03, 0.41 lo +/- 0.02, and 0.24 +/- 0.02 lo for TSM, BSM, and BSM+C, respectively. The BSM and BSM+C delta Lmaxs were different (P less than 0.05). Maximal shortening velocities (Vo) for BSM, elicited at 2, 4, and 8 s by quick release in the course of an isometric contraction were significantly higher than for the BSM+C. Vos showed gradual decreases in all three groups in the later phase of contraction, suggesting the operation of latch bridges.(ABSTRACT TRUNCATED AT 250 WORDS)

Possible mechanism in rat with surviving heart allograft after short course of 15-deoxyspergualin treatment

15-Deoxyspergualin has been reported to be a useful immunosuppressive agent, that is already used to inhibit acute rejection, in clinical transplantation. In the present study, the survival of heart allograft in rats after a short course of DSG treatment and the mechanism underlying induction of DSG-induced heart allograft survival, in the early phase, were studied. Male LEW rats were used as recipients. Male ACI and Wistar rats were used as donors and third party donors, respectively. Survival of ACI heart grafts in LEW recipients, treated with a short course of DSG, beginning from day 4 of grafting, were markedly prolonged, with a mean survival time of 16.6 +/- 5.8 days and 29.8 +/- 3.0 days at the dose of 2.5 mg/kg/day and 5 mg/kg/day, respectively. The mechanism of inducing allograft survival in the early phase, after a short course of DSG treatment, was further analyzed by testing the ability of splenic lymphocytes or serum in MLR assays and transfer experiments. The addition of various concentrations of splenic lymphocytes or serum from DSG treated LEW rat with surviving ACI heart allograft to MLR showed a strong suppression in a cell-dose-dependent manner and serum-dose-dependent manner, both in donor strain and third party MLR. An interesting finding was that there was a constant differential suppressive rate between donor strain party MLR and third party MLR. Moreover, transfer of 2.0 x 10(8) splenic lymphocytes or 2 ml serum from DSG-treated LEW rat with surviving ACI heart allograft, to sublethally irradiated grafted host, did not prolong survival both in ACI heart grafts and third party Wistar grafts. These results suggest that the strong suppresser cells and the suppressor humoral factor(s) play, at least, a partial role in the early phase of rats bearing allograft after a short course of DSG treatment.

[Clinical electrophysiologic effects of lorcainide in patients and its effect on the conduction of accessory pathway in Wolff-Parkinson-White syndrome]

The electrophysiologic effects of the intravenous administration of a new antiarrhythmic drug, lorcainide, were evaluated by programmed electrical stimulation of the heart in 20 patients with and without Wolff-Parkinson-White (WPW) syndromes. Lorcainide shortened the sinus cycle length from 721.0 +/- 125.9 to 649.5 +/- 100.1 ms (P less than 0.001), but did not influence sinus node function and AV node conduction and refractoriness, slightly increased atrial effective period (ERP) (P less than 0.02) and did not change ventricular ERP (P less than 0.2), obviously lengthened atrial conduction time, H, H-V interval and the width of V wave. Lorcainide caused complete antegrade block of the accessory pathway (AP) in six of 9 WPW patients and resulted in exclusive conduction over the AV nodal. His conduction in two patients with atrial flutter. It also prolonged the retrograde conduction time and refractoriness of AP, and prevented initiation of orthodromic atrioventricular tachycardia (O-AVRT) in six of 12 patients by blocking of the retrograde conduction of the AP, increased the cycle length of tachycardia from 321.7 +/- 43.6 to 361.7 +/- 54.9 ms (P less than 0.005) by marked prolongation of retrograde AP conduction time in 6 patients in whom O-AVRT could still be induced. It is concluded that intravenous lorcainide does not affect sinus node and AV node function, slightly influences atrial and ventricular refractoriness, obviously suppresses atrial, His bundle and intraventricular conduction, and is an effective antiarrhythmic drug for patients with WPW by blocking both the antegrade and retrograde conduction of the AP.

A New Synthesis of Xanthones. 2,4,7-Trichloronorlichexanthone and 4,5,7-Trichloronorlichexanthone, Two New Lichen Xanthones

A new synthetic route to norlichexanthone (1,3,6-trihydroxy-8-methyl- 9H-xanthen-9-one) derivatives has been developed by using a Smiles rearrangement of an appropriately substituted depside in the key step. 2,4,7-Trichloronorlichexanthone (22) and 4,5,7- trichloronorlichexanthone (29) have been prepared by this method. The former xanthone (22) was shown to be a constituent of the lichens Lecanora sulphurata and L. flavo-pallescens and the latter (29) a constituent of Micarea austroternaria var. isabellina.

Structure and Synthesis of the Lichen Xanthone Isoarthothelin (2,5,7-Trichloronorlichexanthone)

The structure of isoarthothelin (2,5,7-trichloro-1,3,6-trihydroxy-8-methyl-9H-xanthen-9-one or 2,5,7-trichloronorlichexanthone)(2), a metabolite of an Australian Buellia species and Lecanora broccha, was confirmed by total synthesis. Previous reports of the natural occurrence of (2) refer for the most part to an isomeric compound.

5,7-Dichloro-3-O-methylnorliche-xanthone, a New Xanthone From the Lichen Lecanora broccha

5,7-Dichloro-1,6-dihydroxy-3-methoxy-8-methyl-9H-xanthen-9-one (7) (5,7-dichloro-3-O-methylnorlichexanthone) has been synthesized and shown to cooccur with 2,5,7-trichloro-3-O-methylnorlichexanthone (6) in the lichen Lecanora broccha.

[Influence of finger pressing massage on cAMP and cGMP in the cerebrospinal fluid in prolapsed intervertebral disc]

This paper used RIA method to observe 11 cases of prolapsed intervertebral disc patients, detect the change of cAMP and cGMP in the cerebrospinal fluid before and after finger pressing massage in acupuncture point Weizhong and Chengshan in order to discuss the mechanism of analgesia of finger pressing massage. The results showed that the pain was relieved after finger pressing massage. cAMP of the cerebrospinal fluid increased from 0.51 +/- 0.19 to 0.63 +/- 0.13 pm/ml, in average 32% higher than that before the therapy (P less than 0.05). Since cGMP decreased from 30.52 +/- 26.42 to 23.20 +/- 16.91 pm/ml, it showed that the mechanism of analgesia of finger pressing massage might be due to the fact that the therapy excited selectively endogenous analgesia system, caused the increase of endorphin releasing, and was accompanied by the regulation of cAMP and cGMP.

Elucidation of a protease-sensitive site involved in the binding of calcium to C-reactive protein

C-reactive protein (CRP) is a Ca2+-binding protein composed of five identical 23-kDa subunits arranged as a cyclic pentamer, present in greatly elevated concentration in the blood during the acute phase of processes involving tissue injury and necrosis. In the present work, it was found that treatment of human CRP with Pronase or Nagarse protease produces two major fragments which remain associated in physiological buffers but are separable under denaturing conditions. To localize the cleavage site(s), the fragments were characterized according to molecular mass, amino acid composition, partial amino acid sequence, and reactivity with monoclonal antibodies specific for the fragments and for defined CRP epitopes including residues 147-152 and 199-206. Nagarse protease cleaves the CRP subunit between residues 145 and 146, producing two fragments, 16 and 6.5 kDa (calculated molecular mass). Pronase cleaves the CRP subunit between residues 146 and 147, producing a 16-kDa fragment (A1) and a 6.5-kDa fragment (B); an additional fragment (A2) approximately 1 kDa smaller than fragment A1 is also apparently produced due to a secondary cleavage site in fragment A1. Cleavage appears to be completely inhibited in the presence of 1 mM CaCl2. Ca2+ does not protect cleaved CRP from heat-induced aggregation (i.e., precipitation) as it does the intact protein. Protease-cleaved CRP loses the ability to bind to the Ca2+-dependent ligand phosphorylcholine but remains the ability to bind to the Ca2+-independent ligand arginine-rich histone. Equilibrium dialysis indicates that intact CRP binds 2 mol of Ca2+/mol of subunit with a Kd of 6 X 10(-5) M.(ABSTRACT TRUNCATED AT 250 WORDS)

[Preservation of cytomegalovirus by lyophilization]

The preservation of cytomegalovirus (CMV) by lyophilization was first developed in China. In 4 to 10 days the typical CPE was up to + in the HEL cell line which was inoculated only 0.2 ml suspension of lyophilized strain AD169 or CMV isolated from milk breast. After preserved for 1 year the lyophilized cytomegalovirus strain still contained 1.5-2.0 lgTCID50/0.1 ml in titer of viral infection. The lyophilized strains have been used in the preparation of diagnostic antigen of cytomegalovirus in our department, also the strains were supplied to the whole country.

The discrete dynamics of symmetric competition in the plane

We consider the generalized Lotka-Volterra two-species system xn + 1 = xn exp(r1(1 - xn) - s1yn) yn + 1 = yn exp(r2(1 - yn) - s2xn) originally proposed by R. M. May as a model for competitive interaction. In the symmetric case that r1 = r2 and s1 = s2, a region of ultimate confinement is found and the dynamics therein are described in some detail. The bifurcations of periodic points of low period are studied, and a cascade of period-doubling bifurcations is indicated. Within the confinement region, a parameter region is determined for the stable Hopf bifurcation of a pair of symmetrically placed period-two points, which imposes a second component of oscillation near the stable cycles. It is suggested that the symmetric competitive model contains much of the dynamical complexity to be expected in any discrete two-dimensional competitive model.