Protein C inhibitor (PCI)

PCI is a non-specific serpin that inhibits several proteases of the coagulation and fibrinolytic systems as well as plasma- and tissue kallikreins and the sperm protease acrosin. The precise physiological role of PCI has not been defined yet. Heparin stimulates most PCI/protease reactions, but interferes with the tissue kallikrein/PCI-interaction. Thereby heparin not only regulates PCI-activity but also its specificity in systems containing two or more of its target proteases. This effect is not restricted to heparin, but is also seen with other glycosaminoglycans (GAGs) and large, negatively charged molecules. PCI also binds to GAGs present on the surface of epithelial kidney cells, and GAGs isolated from these cells have a similar effect on PCI activity as heparin. Studies analyzing the role of PCI as an acrosin inhibitor revealed that endogenous PCI is immunocytochemically localized to disrupted acrosomal membranes of morphologically abnormal sperms, while intact sperms are negative for PCI-antigen. In a mouse in vitro fertilization model human PCI inhibited sperm/egg binding and decreased the fertilization rate. Northern blotting of human and mouse mRNA using human and mouse PCI-cDNA probes revealed that in the mouse PCI is exclusively synthesized in the genital tract (testis, seminal vesicle, ovary), while in humans PCI is additionally synthesized in many other organs (e.g., liver, pancreas, heart). Therefore PCI might regulate enzymes involved in fertilization (e.g. acrosin) in both species. Other proteases (e.g., tissue kallikrein) are possibly regulated in a species specific manner by different inhibitors.

Expression of transforming growth factor-alpha and epidermal growth factor receptor in middle ear cholesteatoma

To study the possible autocrine growth stimulation of cholesteatoma epithelium, the expression of transforming growth factor alpha (TGF-alpha) and epidermal growth factor receptor (EGFR) in middle ear cholesteatoma was investigated by immunohistochemical staining techniques. Twenty cholesteatoma samples obtained at operation and six normal skin specimens collected from the external ear canal were used in the study. Immunostaining for TGF-alpha showed a diffuse cytoplasmic staining pattern. It was weakly expressed in the basal layer of the normal epidermal epithelium but was more strongly expressed in all cholesteatoma specimens. EGFR showed a dot-like/diffuse cytoplasmic and cell membrane staining pattern. EGFR-positive cells were seen in the basal layer of normal epidermis. In the cholesteatoma specimens, expression of EGFR was not only confined to the basal layer but persisted into the upper layers of the epithelium. Our findings indicate that an autocrine growth stimulation by TGF-alpha and EGFR may contribute to the unrestrained growth of cholesteatoma epithelium in the middle ear cavity.

[The radiobiologic characteristics of DNA polymerase beta in hepatomas]

DNA polymerase beta activity, its content and gene transcription levels in SMMC-LTNM hepatoma were investigated, using 3H-TTP incorporation, immunocytochemistry and cytoplasmic dot hybridization, respectively. The relations between the biological properties of the enzyme and DNA repair synthesis induced by gamma-ray irradiation were also studied. It was found that DNA polymerase beta activity, its content and the amount of its mRNA were much higher in hepatoma than those in normal hepatocytes (P < 0.01). Following whole-body irradiation of the nude mouse bearing SMMC-LTNM with 2 Gy of gamma ray, the polymerase beta activity in hepatoma increased temporarily and the gene transcription of the enzyme seemed to be more active. DNA polymerase beta participated in DNA repair synthesis and this effect was different between hepatoma and hepatocyte because of the biological differences of DNA polymerase beta. The results presented here indicated that DNA polymerase beta could affect radiation damage and radiotherapy of cancer.

Bleomycin-induced pulmonary fibrosis in transgenic mice that either lack or overexpress the murine plasminogen activator inhibitor-1 gene

Impaired fibrinolytic activity within the lung is a common manifestation of acute and chronic inflammatory lung diseases. Because the fibrinolytic system is active during repair processes that restore injured tissues to normal, reduced fibrinolytic activity may contribute to the subsequent development of pulmonary fibrosis. To examine the relationship between the fibrinolytic system and pulmonary fibrosis, lung inflammation was induced by bleomycin in transgenic mice that either overexpressed or were completely deficient in murine plasminogen activator inhibitor-1 (PAI-1). 2 wk after 0.075 U of bleomycin, the lungs of transgenic mice overexpressing PAI-1 contained significantly more hydroxyproline (118 +/- 8 micrograms) than littermate controls (70.5 +/- 8 micrograms, P < 0.005). 3 wk after administration of a higher dose of bleomycin (0.15 U), the lung hydroxyproline content of mice completely deficient in PAI-1 (49 +/- 8 micrograms) was not significantly different (P = 0.63) than that of control animals receiving saline (37 +/- 1 micrograms), while hydroxyproline content was significantly increased in heterozygote (77 +/- 12 micrograms, P = 0.06) and wild-type (124 +/- 19 micrograms, P < 0.001) littermates. These data demonstrate a direct correlation between the genetically determined level of PAI-1 expression and the extent of collagen accumulation that follows inflammatory lung injury. These results strongly support the hypothesis that alterations in fibrinolytic activity influence the extent of pulmonary fibrosis that occurs after inflammatory injury.

Vitronectin is not essential for normal mammalian development and fertility

Vitronectin (VN) is an abundant glycoprotein present in plasma and the extracellular matrix of most tissues. Though the precise function of VN in vivo is unknown, it has been implicated as a participant in diverse biological processes, including cell attachment and spreading, complement activation, and regulation of hemostasis. The major site of synthesis appears to be the liver, though VN is also found in the brain at an early stage of mouse organogenesis, suggesting that it may play an important role in mouse development. Genetic deficiency of VN has not been reported in humans or in other higher organisms. To examine the biologic function of VN within the context of the intact animal, we have established a murine model for VN deficiency through targeted disruption of the murine VN gene. Southern blot analysis of DNA obtained from homozygous null mice demonstrates deletion of all VN coding sequences, and immunological analysis confirms the complete absence of VN protein expression in plasma. However, heterozygous mice carrying one normal and one null VN allele and homozygous null mice completely deficient in VN demonstrate normal development, fertility, and survival. Sera obtained from VN-deficient mice are completely deficient in "serum spreading factor" and plasminogen activator inhibitor 1 binding activities. These observations demonstrate that VN is not essential for cell adhesion and migration during normal mouse development and suggest that its role in these processes may partially overlap with other adhesive matrix components.

Plasma levels of beta-endorphin, leucine enkephalin and arginine vasopressin in patients with essential hypertension and the effects of clonidine

In order to investigate the changes of endogenous opiate systems in hypertension and their possible role in the pathogenesis in hypertension, we measured plasma concentrations of beta-endorphin, leucine-enkephalin, neurotension, arginine vasopressin, plasma renin activity and angiotensin II by radioimmunoassay in 60 normal persons and 120 patients with essential hypertension. The results showed that the patient group had lower levels of beta-endorphin and leucine enkephalin (P < 0.001), higher levels of arginine vasopressin, plasma renin activity and angiotensin II (P < 0.01, P < 0.05 and P < 0.05, respectively), and normal level of neurotensin, as compared with those in normal group. Plasma levels of leucine-enkephalin was correlated negatively to the mean artery pressure (r = -0.196, P < 0.05). Plasma level of arginine vasopressin was correlated to the duration of the hypertension (r = 0.216, P < 0.05). After 150 min and 14 days of treatment with clonidine, plasma levels of beta-endorphin, leucine-enkephalin increased significantly (< 0.01) and correlated negatively with the decrease of the mean artery pressure (r = -0.340 and r = -0.436 at 150 min, r = -0.369 and r = -0.441 on the 14th day, respectively, P < 0.01). Plasma renin activity and angiotensin II decreased significantly (P < 0.05 and P < 0.01). Arginine vasopressin and neurotensin did not change significantly. After intravenous administration of opiate antagonist-naloxone, the blood pressure and heart rate increased significantly (P < 0.01). The results suggested that the changes of endogenous opioids may be involved in the pathogenesis of hypertension and in the antihypertensive action of clonidine.

The reforms of the Chinese health care system: county level changes: the Jiangxi Study

A survey of the economic performance of county hospitals in middle income counties in Jiangxi province was undertaken in 1989. The survey considered the impact of health policy changes in the P.R.C., especially cost recovery, decentralization, managerial changes and the promotion of traditional medicine. The financial records of county level hospitals and traditional medicine hospitals for the period 1980-89 were examined, as were patient expenditures. Opinions of those responsible for policy execution were surveyed. The data showed that hospitals from which state subsidy had been removed had become dependent on medicine sales and increasing itemization of treatment to recover costs. The insurance status of patients influenced the length of stay and levels of payment. Uninsured peasants had a shorter stay and were charged more for items of treatment. Traditional Medicine hospitals saw more outpatients than County hospitals, but were more likely to have a deficit. They were also very dependent on medicine sales for income. Most officials questioned felt that the changing system caused problems, but at the same time were eager to invest in equipment as a source of revenue.

[beta]-Tubulin Accumulation and DNA Replication in Imbibing Tomato Seeds

The activation of the cell cycle in embryo root tips of imbibing tomato (Lycopersicon esculentum Mill. cv Lerica) seeds was studied by flow cytometric analyses of the nuclear DNA content and by immunodelection of [beta]-tubulin. With dry seeds, flow cytometric profiles indicated that the majority of the cells were arrested at the G1 phase of the cell cycle. In addition, [beta]-tubulin was not detectable on western blots. Upon imbibition of water, the number of cells in G2 started to increase after 24 h, and a 55-kD [beta]-tubulin signal was detected between 24 and 48 h. Two-dimensional immunoblots revealed at least three different [beta]-tubulin isotypes. Thus, [beta]-tubulin accumulation and DNA replication were induced during osmotic priming. These processes, as well as seed germination rate, were enhanced upon subsequent imbibition of water, compared with control seeds that imbibed but were not primed. By contrast, when aged seeds imbibed, DNA replication, [beta]-tubulin accumulation, and germination were delayed. In all cases studied, both DNA replication and [beta]-tubulin accumulation preceded visible germination. We suggest that activation of these cell-cycle-related processes is a prerequisite for tomato seed germination. Furthermore, [beta]-tubulin expression can be used as a parameter for following the initial processes that are activated during seed imbibition.

[The use of measuring serum soluble IL-2 receptor levels in cyclosporine-A treated lupus nephritis]

Twenty-one patients with Lupus Nephritis (LN) were treated with cyclosporine-A (CsA) for three months. Serum soluble interleukin-2 receptors (SIL-2R) were measured before and after treatment and correlated prospectively with serologic findings of LN activity. The patients had significantly higher IL-2R level before treatment (during LN flare) than after treatment (disease remission). A significant positive correlation was present between serum SIL-2R and proteinuria, and ANA as well, whereas the SIL-2R levels in LN patients were inversely correlated with serum levels of C3 and CH50. These observations suggest that serum SIL-2R level is an useful marker of disease activity in LN and may serve as a helpful adjunct in the management of this disorder.

Interest of argyrophilic proteins nucleolar organizer regions (AgNOR) to estimate the reactivity of T cell clones against autologous malignant B-NHL cells

The silver-stained acidic proteins of interphase nucleolar organizer regions (AgNOR) were studied to assess the reactivity of 11 T cell clones (Tcc) against autologous B-NHL cells. Tcc, derived from tumour-infiltrating T lymphocytes of seven patients, were cultured in the presence of irradiated autologous B-NHL cells with recombinant IL-2. Then the percentage of activated T cells expressing the CD25 antigen and their proliferating rate (measured by [3H]thymidine incorporation) were estimated. Simultaneously, at the end of this culture period, B-NHL cells were eliminated by using a cell-sorter, and the resulting purified T cells were studied for AgNOR expression. Tcc cultured without B-NHL cells served as controls. In eight out of the 11 Tcc, the increase in [3H]thymidine incorporation and CD25 expression paralleled the increase of AgNOR area and number. By contrast, in the three remaining Tcc, we observed a decrease (one Tcc) or an increase (two Tcc) of AgNOR parameters, whereas CD25 expression and/or [3H]thymidine incorporation remained unchanged in comparison to control cultures. We concluded that quantification of AgNOR should be a more sensitive technique than thymidine incorporation and CD25 expression for detecting the activation in vitro of T cells induced by autologous B-NHL cells.

HIV risk behaviors but absence of infection among drug users in detoxification centers outside Yunnan province, China, 1993

OBJECTIVES

To date, HIV spread in China has occurred principally among injecting drug users (IDU) in remote border regions of Yunnan province. We therefore sought to better understand the risks for and prevalence of HIV infection among drug users in parts of China outside Yunnan province.

METHODS

A behavioral survey of drug use and AIDS-related knowledge was conducted among all consenting drug users who entered treatment from 1 November to 31 December 1993 in seven provincial drug detoxification centers outside Yunnan province. After giving verbal informed consent, all drug users were tested for HIV.

RESULTS

Of the 1293 study participants, 207 (16%) reported injecting drugs. The proportion of IDU among all drug users varied widely by region, from 1% in Sha'anxi and Gansu provinces in the northwest region to 58% in Guangxi province in the south. IDU were more likely than non-IDU to be single and unemployed or self-employed, but did not differ in other demographic aspects. Among all drug users, 2% reported sharing needles without cleaning equipment, while 5% shared with some cleaning. Although 1060 (82%) drug users had heard of AIDS and most knew about its sexual (79%), parenteral (77%), and perinatal (60%) modes of transmission, many had misconceptions about its spread by casual contact. Of the 207 IDU tested for HIV, none were HIV-positive (95% confidence interval, 0--1.4).

CONCLUSION

The absence of HIV infections detected in this study suggests that the prevalence of HIV is currently low among IDU in China outside the Yunnan province. However, the behavior of these IDU puts them at high risk for HIV infection. Prevention efforts are needed to prevent the spread of HIV among IDU throughout China and to avoid the experience of neighboring countries in Asia.

N-nitrosodimethylamine and 7-methylguanine DNA adducts in tissues of rats fed Chinese salted fish

Previous studies have demonstrated that rats fed Chinese salted fish developed carcinomas of the nasopharynx and nasal cavity. In the present work the contents of nitrosamines in salted fish from the city of Guangzhou, southern China, and the contents of nitrosamines and possible nitrosamine-induced DNA adducts in organs of rats fed the fish were analysed. Similar levels of N-nitrosodimethylamine (NDMA) were detected in tough and soft salted fish. The NDMA content in steamed fish was higher than in raw fish. In vitro incubation of salted fish with gastric juice significantly increased the level of NDMA. NDMA was found in liver and kidney from rats fed salted fish for 2 years, but no dose-dependence was found between salted fish treatment and NDMA content. The level of 7-methylguanine in rat liver DNA was found to be slightly higher than in DNA from nasopharynx. However, there were no significant differences in the level of 7-methylguanine in DNA samples from rats fed salted fish and rats fed standard diet.

Isolation and some properties of glycated D-glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle

Glycated D-glyceraldehyde-3-phosphate dehydrogenases (GAPDH) from rabbit muscle and human erythrocytes have been investigated. The specific activity of the non-glycated GAPDH from rabbit muscle is approx. 180 units. (One unit is defined as the specific activity required to convert 1 microM of substrate/min per mg of enzyme.) The activity of the glycated enzyme, consisting of two sugars per tetramer, is lower than that of the non-glycated GAPDH. Non-enzymic transamination of the N-termini of glycated GAPDH (gGAPDH) indicates that they are not blocked by glycation. The rate of modification of thiols (Cys-149) with 5,5'-dithiobis-(2-nitrobenzoic acid) was greater for the glycated than the non-glycated enzymes. The rate of modification of amino groups of Lys residues of gGAPDH with o-phthalaldehyde was greater for the non-glycated enzyme. In 0.18 M guanidine-HC1 solution, the emission intensity at 410 nm of a fluorescent NAD+ derivative introduced into the active site decreased to 80%, whereas that of gGAPDH decreased to 50%. This suggests that the glycated sites are near the active site; glycation of the enzyme leads to a change of the microenvironment of Cys-149, alters the conformation of the active site and decreases the activity.

[Correlation of fetal umbilical artery velocity waveforms with placental pathology and biochemistry]

The ratio of peak systolic to least diastolic flow velocity (S/D) of the umbilical artery was measured in 119 pregnant women and its relation with placental pathology were studied. Results obtained indicated that S/D ratio decreased gradually with advanced gestational age and showed a negative correlation (r = -0.972 8, P < 0.01). A ratio of < 3 was defined as normal value. Patients were divided into 2 groups according to the S/D ratio and their placental histological findings were compared. The number of small arteries in the tertiary villi stem and syncytial vascular membranes were significantly less in group 2 (S/D > or = 3) than that in group 1 (S/D < 3, P < 0.01). The counts of villous syncytial knots and stroma fibrosis of villi were more significant in the placenta of group 2 as well. The mean value of molondialdehyde in placenta of group 2 was significantly higher (P < 0.01) than that of group 1, while superoxide dismutase value is to the contrary (P < 0.01). These indicated that there was a reduced circulation resistance in placenta during normal pregnancy and remained stable till term. When S/D > or = 3, it indicated that physiological and biochemical changes occurred in placenta and the outcome of pregnancy might be affected.

Inhibition of PAF-induced human platelet aggregation by antithrombotic nipecotomides

Nipecotamides (piperidine-3-carboxamides) are potent inhibitors of platelet aggregation induced by a variety of agonists in vitro and in vivo. The inhibitory effects of six structural types of nipecotamides on human platelet aggregation induced by platelet-activating factor (PAF) in vitro, are studied. Evaluation of 15 racemates and stereoisomers of two nipecotamides showed that bis-nipecotoyl alkanes were more active than their mono congeners. Mono- and bis-nipecotoyl decanes were more potent than the corresponding hexanes. Lipophilicity was found to play a significant role in the antiplatelet activity of these compounds. The stereoselectivity in the PAF-antagonist potential of nipecotamides was less pronounced than that resulting from their action on ADP- or collagen-induced aggregation. Oxidation of the two benzylic carbon atoms of alpha, alpha'-bis[3-(N,N-diethylcarbamoyl)piperidino]-p-xylene.2HBr (A-1) to form 1,4-bis[3-N,N-diethylcarbamoyl) piperidino]benzenedicarboxamide (A-40K), which has a second set of carbonyl oxygens but lacks basic N atoms, resulted in a remarkable loss of ADP-antagonist potency while retaining PAF-antagonist activity. It is suggested that in addition to their membrane effects, nipecotamides act at other sites, including the PAF receptor. Double reciprocal plots of PAF binding to gel-filtered platelets (GFP) in the presence and absence of a typical nipecotamide (A-1C) were indicative of competitive inhibition (Ki = 19.28 microM). Scatchard analysis of 3H-PAF binding to GFP suggested the presence of high, intermediate (I) and low affinity binding sites, of which the I site gave a KD/app of 0.332 nM with an estimated 564 sites/platelet. Key interactions of nipecotamides with the PAF receptor appear to be the following (i) electrostatic interactions of the two amide oxygens with a primary set of electropositive areas spaced at 5-7 A, (ii) in the case of appropriate compounds, electrostatic interactions of the two amide oxygens spaced at 10-12 A with corresponding secondary receptor sites carrying positive electrostatic potential, (iii) a hydrophobic moiety fitting into a hydrophobic pocket in the receptor, and (iv) the cationic piperidine N+ (at pH 7.4) interacting with a counterion, probably aspartic acid.

Small repeating units within the Ureaplasma urealyticum MB antigen gene encode serovar specificity and are associated with antigen size variation

Ureaplasma urealyticum is a common commensal of the female lower urogenital tract, yet it has been shown to be an important cause of chorioamnion infection, respiratory and central nervous system disease, and death in premature infants. It has been suggested that only certain serovars are capable of producing invasive disease. However, we previously showed that many serotypes are invasive and that perhaps antigen variability and host factors are more important determinants of ureaplasma infections than are different serotypes per se. The molecular characterization in this report describes a mechanism available to ureaplasmas for producing antigen variation. That antigen, designated MB and previously identified on U. urealyticum, contains serovar-specific and cross-reactive epitopes, is produced both in vitro and in vivo, is a predominant antigen recognized during ureaplasma infections of humans, undergoes a high rate of size variation in vitro, and is size variable on invasive ureaplasma isolates. In the present study, we cloned and sequenced the gene of the MB antigen from serovar 3, the serovar most commonly isolated from humans. The 3' two-thirds of the gene was shown to contain identical 18-nucleotide tandem repeats. PCR analysis and direct sequencing of two variants indicated that alterations within this repeat region are responsible for the size variation of the MB antigen. Intact recombinant serovar 3 MB antigen and truncated products, expressed by coupled in vitro transcription and translation of the cloned gene, were immunoprecipitated by both a serovar-specific monoclonal antibody and the serum of a U. urealyticum-infected patient, and these results identified the repeat region of the MB antigen as serovar defining. Resolution of the precise amino acids responsible for specific epitopes and characterization of similar genes in the other serovars should yield reagents useful in elucidating the role of antigen size variants in disease production and the role of specific antibody in protection from ureaplasma disease.

[Experimental observations of the quantitative changes of proteoglycan in homogenous cartilage graft in the guinea pig]

The present work was to study the quantitative change of proteoglycan (PG) in homogenous cartilage graft in the guinea pig. Histological, histochemical and biochemical studies were undertaken at different times after grafting. The results revealed that there was a marked reducing trend of matrix PG within four weeks after grafting. Four weeks afterwards all indexes except hexuronic acid restored slowly and approached the level of the control group. By the 20th week, the activity of neutromucopolysaccharide, hexosamine, acid-mucopolysaccharide and alkaline phosphatase restored to 73.6% -93.7% of the control group (P > 0.05). The changes probably were caused by immune reaction and operative trauma. PG in the cartilage matrix forms a barrier for the chondrocytes, protecting the host's immune system from contacting and reacting with the chondrocytes of the graft. Though the core protein of PG has antigenicity, it is surrounded by acidmucopolysaccharide that has no antigenicity. We concluded that it is very important to maintain a high level of PG in order to prolong the survival of a cartilage graft.

[Immunocomplexes in tuberculous lesions]

The immunohistochemical staining was used to detect the BCG antigen, IgG, IgM, IgA and the complement C3 in the tuberculous lesions. The results showed that the III type of allergic reaction induced by immunocomplexes (IC) was one of the pathogenesis of tuberculosis. Detection of specific IC in tuberculous lesions was helpful for pathologic diagnosis of tuberculoions.

Design and synthesis of piperidine-3-carboxamides as human platelet aggregation inhibitors

A detailed structure-activity analysis was carried out using eight 1-alkyl(aralkyl)nipecotamides (type 5), 33 bis-nipecotamidoalkanes and aralkanes (type 6), and 7 N,N'-bis(nipecotoyl)-piperazines (type 7) as inhibitors of human platelet aggregation. Steric factors played an important role in determining the activity of type 5 compounds possessing an an appropriate degree of hydrophobic character. Types 6 and 7 compounds were more potent than the corresponding type 5 molecules. Hydrophobic character appeared to influence the activity of type 6 compounds. A 3-substituent on the piperidine ring was necessary for antiplatelet activity; the substituent should be preferably an amide with its C attached directly to the ring. 3,5-Disubstitution and 2-substitution led to a decline in activity. Optimal activity was attained when the two nipecotoyl ring N atoms were connected by an aralkyl group, and separated by approximately 7 A. It is suggested that van der Waals forces and pi interactions may govern the inhibitor-platelet interaction. The most potent type 6 inhibitor was alpha,alpha'-bis[3-(N-ethyl-N-butylcarbamoyl)piperidino]-p-xylene (6i). The most potent type 5 compound was 1-decyl-3-(N,N-diethylcarbamoyl)piperidine (5a). Any substitution on the piperazine ring of type 7 compounds led to a decline in activity, the most active analog being N,N'-bis(1-decylnipecotoyl)piperazine (7a). It is suggested that nipecotamides interact with anionic platelet sites located 7 A from each other and connected by a hydrophobic well.

Synthesis of stereoisomers of antithrombotic nipecotamides

The stereoisomers of alpha,alpha'-bis[3-(N,N-diethylcarbamoyl)-piperidino]-p-xylene (1) were synthesized. Rac ethyl nipecotate was resolved by diastereomeric (-)-D- and (+)-L-tartrate salt formation. The enantiomeric esters were hydrolyzed to the corresponding nipecotic acids, which were then converted into t-BOC derivatives. Treatment of the latter with diethylamine/isobutyl chloroformate and removal of the t-BOC protecting group afforded (R)- and (S)-N,N-diethylnipecotamides. Condensation of the latter with alpha,alpha'-dibromo-p-xylene gave (R,R)- and (S,S)-1. The meso-diastereomer was obtained by stereospecific synthesis in addition to our earlier procedure involving fractional crystallization of the diastereomeric mixture obtained by synthesis. The latter was resolved earlier into 1A, 1B, and 1C using chiral high-performance liquid chromatography (HPLC). Based on the stereospecific synthesis now achieved, 1A and 1B are assigned the configurations, (R,R) and (S,S) respectively, and 1C is assigned the meso configuration. The (R,S) structure of the latter is also confirmed by X-ray crystallography.

[3H]-noradrenaline release from streptolysin-O permeated rat cortical synaptosomes: enhancement of the Ca(2+)-induced signal

We examined [3H]-noradrenaline ([3H]-NA) release from rat brain cortical synaptosomes permeated with streptolysin-O (SLO) under a variety of conditions. Three temperatures (20 degrees C, 25 degrees C, and 30 degrees C) were tested at different times of permeation. Lowering the incubation temperature to 20 degrees C decreased basal release, but Ca(2+)-induced [3H]-NA release increased slightly. Also, the incubation time to achieve the maximal ratio of Ca(2+)-induced release to basal release shifted to longer times with decreasing incubation temperature. If the synaptosomes were permeated with SLO before release was triggered, similar results were observed. Permeation at 20 degrees C allowed [gamma-32P] ATP and cAMP-dependent protein kinase (PKA) catalytic subunit to rapidly enter the synaptosomes to phosphorylate synapsins. Lactate dehydrogenase (LDH) efflux was time- and SLO-concentration dependent. The fact that 0.1 mM Cd2+ did not inhibit [3H]-NA release from permeabilized synaptosomes indicated that permeabilization by SLO was complete under these conditions. This also suggests that the release machinery involved after Ca2+ entry is not sensitive to Cd2+.

[Silicone oil removal in 31 cases]

Silicone oil removal was performed on 32 eyes of 31 cases after silicone oil injection for an average of 13.9 months. The reasons for the silicone oil removal are the complications such as cataract, glaucoma, emulsification of the silicone oil and so on. Complete retinal reattachment without any complications was found in 6 eyes of the 32 cases. Retinal reattachment remained in place in 24 eyes after the removal, and 24 eyes achieved postoperative visual acuities > or = 0.02. After the removal, in 7 of 8 eyes with complication, retinal detachment reoccurred. The significance and the timing of the silicone oil removal were discussed in this paper.

Differences in the growth pattern and clinical course of EBV-LMP1 expressing and non-expressing nasopharyngeal carcinomas

All low differentiated or anaplastic forms of nasopharyngeal carcinoma (NPC) carry multiple copies of EBV-DNA and express EBNA1. The major membrane protein, LMP1, is only expressed in 65% of the tumours. The physiological function of LMP1 in the viral life cycle is unknown, but it has been shown to transform established rodent fibroblasts and immortalised human keratinocytes in vitro, and to increase the likelihood of a malignant transformation. We studied 74 cases collected from the Shanghai and Guanzhou areas in China. LMP1 expression was assessed in tumour biopsies by immunoblotting. Clinical and follow-up data were evaluated according to the classification of WHO. The laboratory and the clinical data were assembled in a mutually independent double blind fashion. Our findings indicate that the LMP1-positive tumours grew faster and more expansively than LMP1-negative tumours, but nevertheless had a better prognosis. LMP1-negative tumours recurred at a higher frequency, and showed an increased tendency to metastasise.

Spermine potentiation of recombinant N-methyl-D-aspartate receptors is affected by subunit composition

The present study shows that both the NR1 and NR2 subunits critically affect spermine potentiation of heteromeric recombinant N-methyl-D-aspartate receptors. NR1(011), the most prominent NR1 splice variant in rat forebrain, and NR1(100), prominent in midbrain, were expressed in Xenopus oocytes singly and in combination with NR2A, NR2B, and NR2C subunits. As for NR1(011) homomers, NR1(011)/NR2B receptors exhibited spermine potentiation by two mechanisms: by increasing glycine affinity and by increasing current through receptors with bound N-methyl-D-aspartate and glycine. NR1(011)/NR2A receptors exhibited only the increase in glycine affinity, and NR1(011)/NR2C receptors exhibited neither. As for NR1(100) homomers, NR1(100)/NR2B and NR1(100)/NR2A receptors exhibited spermine potentiation only by increasing the glycine affinity. Spermine produced no potentiation of NR1(100)/NR2C receptors. Thus, the NR2B subunit "permits" both forms of spermine potentiation, the NR2A subunit permits spermine potentiation only by increasing the glycine affinity, and th NR2C subunit permits neither form of potentiation. Spermine actions on NR1/NR2 showed little voltage dependence. These observations are of interest because the NR1 and NR2 subunits are differentially distributed and developmentally regulated. At early postnatal ages, NR2B subunit mRNA was more highly expressed than NR2A and NR2C mRNAs in hippocampus, neocortex, and caudate-putamen. These findings account for many of the observed differences among neurons in polyamine actions and suggest that these actions will vary in a cell-specific and age-related manner.

Synergistic antiplatelet effects of a nipecotamide A-1C and low dose aspirin

1. The effects of an antithrombotic nipecotamide, A-1, and aspirin were examined separately and in combination, on human platelet aggregation in vitro and on collagen+epinephrine-induced thromboembolic death of mice in vivo. 2. Concurrent addition of the two agents to a platelet suspension resulted in a supraadditive inhibition. Racemic A-1 and its meso diastereomer A-1C behaved similarly in this respect. The IC50 value of rac. A-1 declined from 46.25 to 18.4 microM in the presence of aspirin. 3. In vivo, concurrent administration of A-1C and aspirin produced significant potentiation of antithrombotic activity. A 2-fold reduction in the ED50 of A-1C occurred when it was coadministered with aspirin to mice; also, the toxicity reduced slightly, increasing the therapeutic index by a factor of 2.2. 4. The design and synthesis of new compounds possessing the structural features of the two molecules appears to provide superior antithrombotic agents.

Cytokines and the Th1/Th2 paradigm in transplantation

With studies elucidating the cytokine programs associated with T-cell activation, allograft rejection and tolerance induction, the Th1/Th2 paradigm has become a unifying model to explain the observed cytokine profiles. The proof that these cytokines mediate allograft tolerance, however, is at best indirect. More recent studies highlighting the redundant and pleiotropic nature of cytokine networks suggest that the Th1/Th2 paradigm may not be sufficient to explain fully the mechanisms underlying allograft tolerance.

Expression of Ki67 antigen, epidermal growth factor receptor and Epstein-Barr virus-encoded latent membrane protein (LMP1) in nasopharyngeal carcinoma

The expression of Ki67 antigen, epidermal growth factor receptor (EGFR) and the Epstein-Barr virus (EBV)-encoded latent membrane protein (LMP1) in nasopharyngeal carcinoma (NPC) was immunohistochemically determined. In cases with sufficient material western blot analysis was applied to analyse the LMP1 expression. Biopsies from 20 Chinese and 3 Swedish patients with NPC were included in the study. Our results demonstrated a nuclear Ki67 staining, a membrane EGFR staining, and a dot-like cytoplasmic and/or membrane LMP1 staining pattern in tumour cells of NPC. The proportion of Ki67-positive cells correlated with tumour stage. A strong expression of EGFR was frequently seen in patients with tumour stages III and IV and was paralleled by a higher proportion of Ki67-positive cells. The majority of the LMP1-positive cases strongly expressed EGFR and had a higher proportion of Ki67-positive cells, indicating a possible effect of EBV LMP1 on the proliferation of tumour cells in NPC. The increased expression of EGFR and Ki67 in NPC at late tumour stage indicates their possible use in malignancy grading of NPC.

Injecting drug use and HIV infection in southwest China

OBJECTIVES

To determine the prevalence of drug injection among drug users, the seroprevalence of HIV and risk factors for HIV infection among injecting drug users (IDU), and to determine heterosexual transmission of HIV among IDU and their spouses in southwest China.

METHODS

Using a cross-sectional design, we conducted an HIV seroprevalence and behavioral survey in three rural counties of Yunnan province, Ruili, Longchuan and Luxi in southwest China, bordering Myanmar (Burma). A total of 860 drug users were recruited in randomly selected communities at the three study sites (response rate, 97%). In addition, a random sample of 62 wives of HIV-infected IDU were assembled from 460 known HIV-positive IDU in Ruili and Longchuan (response rate, 81%).

RESULTS

In the sample of 860 drug users, 33% reported injecting drugs. Among the 282 subjects who injected drugs, 82% began intravenous drug use after 1988; 64% injected drugs at least once every day. All subjects shared needles but none cleaned the injection equipment with alcohol or bleach. Overall, 49% tested HIV-positive. HIV seropositivity was independently correlated with a longer history of drug injecting, daily injecting, frequent needle-sharing, being younger, and living in Ruili county. Among the 62 wives of HIV-positive IDU, none used condoms during sex and 10% tested HIV-positive.

CONCLUSIONS

We conclude that the introduction of HIV into drug-using communities and the rapid increase in heroin injecting in this population appear to have triggered an explosive HIV epidemic among IDU in southwest China. We recommend that AIDS prevention efforts should begin immediately and focus on discouraging the shift from opium smoking to heroin injecting, needle-sharing, and unprotected sex among drug users and their partners.

Inhibition of acrosin by protein C inhibitor and localization of protein C inhibitor to spermatozoa

Protein C inhibitor (PCI) is synthesized by cells throughout the male reproductive tract and is present in high concentrations (220 micrograms/ml) in seminal plasma. Seminal plasma as well as the acrosome of spermatozoa are rich in possible target proteases for PCI. We analyzed the interaction of PCI with acrosin, a serine protease stored in its zymogen form in the acrosome of spermatozoa. Purified human PCI inhibited the amidolytic activity of purified boar acrosin with an apparent second-order rate constant of 3.7 x 10(4) M-1.s-1. Inhibition was paralleled by the degradation of PCI from its 57- to its 54-kDa form. Human PCI also inhibited the amidolytic activity of activated human sperm extracts and formed complexes with acrosin as determined by an enzyme-linked immunosorbent assay. Immunocytochemistry revealed that morphologically abnormal spermatozoa stained for PCI antigen, whereas morphologically normal spermatozoa were negative. In immunoelectron microscopy, PCI was exclusively localized in the immediate vicinity of disrupted acrosomal membranes of sperm heads. These data suggest that PCI might function as a scavenger of prematurely activated acrosin, thereby protecting intact surrounding cells and seminal plasma proteins from possible proteolytic damage.

Ureaplasma urealyticum biovar specificity and diversity are encoded in multiple-banded antigen gene

Ureaplasma urealyticum is a commensal organism of the lower genital tract of females, but in a subpopulation of individuals, it can invade the upper genital tract. It is a significant cause of chorioamnionitis and neonatal morbidity and mortality. There are 14 recognized serovars of U. urealyticum; these can be divided into two distinct clusters or biovars. Biovar 1 is composed of serovars 1, 3, 6, and 14, Biovar 2 is composed of serovars 2, 4, 5, 7, 8, 9, 10, 11, 12, and 13. We previously identified a surface antigen, the multiple-banded (MB) antigen, which contains both serovar-specific and cross-reactive epitopes. Genotypic characterization of the C-terminal region of the MB antigen of serovar 3 indicates that serovar specificity and MB antigen size variation reside in that domain. In the present study, we used PCR analysis with primers derived from the serovar 3 MB antigen gene DNA sequence to determine if the MB antigen gene was present in the remaining 13 reference serovars as well as in invasive clinical isolates. The results indicated that not only was the MB antigen gene present in all serovars but that the genes' 5' regions were markers of biovar specificity and diversity. Further analysis of this region should reveal the phylogenetic relationship among serovars of U. urealyticum and, possibly, their invasive potential.

Effect of beta-lymphocyte- and NPC-derived EBV-LMP1 gene expression on in vitro growth and differentiation of human epithelial cells

The effect of expression of the Epstein-Barr-virus (EBV) latent membrane protein (LMP1) derived from B-lymphocytes (B) and nasopharyngeal carcinoma (NPC) (C) on the in vitro growth and differentiation of a human keratinocyte line, Rhek-1, was analyzed in clonal growth and in in vitro differentiation assays. In contrast to the polygonal parental cells, the B-LMP1-expressing sublines were spindle-shaped while the C-LMP1-expressing cells were pleomorphic. Both B- and C-LMP1-expressing sublines showed increased proliferation as evidenced by: (1) higher colony-forming efficiency (CFE) and larger colony size at reduced serum levels; (2) an increased number of epithelial cell layers formed in the air-liquid-interface culture system and (3) increased expression of proliferative cell nuclear antigen (PCNA). At low serum concentration, the C-LMP1-expressing sublines formed larger colonies than those expressing B-LMP1. In the air-liquid-interface culture system, both B- and C-LMP1-expressing lines showed reduced epithelial differentiation resulting in reduced stratification and reduced involucrin expression similar to those of the cancer cell line, Siha. The results of the present study indicate that the expression of LMP1 in human keratinocytes is associated with morphological transformation and predisposes these cells to a more neoplastic phenotype. The structural difference between the 2 genes responsible for the functional differences and transforming ability will be pinpointed in further experiments.

Antigen expression of epithelial markers, collagen IV and Ki67 in middle ear cholesteatoma. An immunohistochemical Study

The expression of epithelial markers (cytokeratins, Filaggrin, BerEp4 and EMA), collagen IV and Ki67 was studied immunohistochemically in cholesteatoma and compared with that in epidermis of meatal skin, squamous epithelium of eardrum and simple epithelium of middle ear mucosa. MNF116 (cytokeratin 10, 17, 18) stained the full layer of normal epithelium and all cholesteatoma specimens. CK10 and Filaggrin were expressed in the upper layer of epidermis but more diffusely in cholesteatoma. BerEp4 was found in the basal layer of normal epithelium but was detected in most epithelial cells in cholesteatoma matrix. Variability was observed in EMA and CK14 immunostaining. Collagen IV was localized in the basement membrane of normal epithelium with a continuously staining pattern, an observation also made in the cholesteatomas studied. However, in one of these small areas the basement membrane was not stained with collagen IV. Ki67 was expressed in nuclei of the cells in the basal layer of normal epithelium but extended to epithelial cells in the upper layers of cholesteatoma matrix. The results of the present study indicate that the expression pattern of epithelial markers in cholesteatoma corresponds to that in normal epidermis. The increasing expression of BerEp4 and Ki67 confirms the hyperproliferative nature of cholesteatoma. Whether or not the lack of expression of collagen IV in one of the cholesteatomas reflects a true degradation of the basement membrane needs further investigation in extended materials.

[Prevalence of HIV and HCV among injecting drug users (IDUs) in Yunnan, China]

Prevalence of HIV and HCV was studied among 507 IDUs in Yunnan Province. The results reveal that sharing needles with other IDUs is one of the primary pathways to transmit both HIV and HCV. The rates of HIV and HCV infection in the IDU group is 66.5% and 94.9% respectively, which is significantly higher than those in the non-IDU group. There is a direct correlation between the rates of HIV and HCV antibody positive. 97.5% HCV (+) subjects are also HIV (+); and 57% HIV (+) subjects are HCV (+). It is suggested that all IDUs should be encouraged to stop using drugs to prevent HIV and HCV transmission.

B7(+)-transfectant tubular epithelial cells induce T cell anergy, ignorance or proliferation

We have previously established that interferon (IFN)-gamma stimulated, antigen-pulsed tubular epithelial cells (TEC) stimulate antigen (Ag) specific activation of T cell hybridomas to express IL-2. In contrast, these Ag pulsed TEC do not stimulate T helper 1 (Th1) clones to proliferate, but rather render them unresponsive, since Ag pulsed spleen cells cannot restore these cells to proliferate. The interaction of the T cell CD28 surface protein with its ligand B7 expressed on Ag presenting cells bearing Ia is a potent co-stimulatory signal capable of inducing T cell proliferation. Hence, the lack of B7 on TEC was hypothesized to be responsible for anergy in these Th1 cells. Therefore, the B7 gene was transfected into a SV40 transformed TEC or Chinese hamster ovary (CHO) cells, and created TEC and CHO cells expressing surface B7 protein. TEC-B7 (IFN-gamma stimulated, Ag pulsed) express Ia and induce IL-2 production by T cell hybridomas. In contrast, T cell proliferation was not induced by TEC-B7 or CHO-B7 cells; however, these Th1 cells were not anergic since they could be stimulated to proliferate to Ag pulsed spleen cells (immunological ignorance). However, co-cultivating TEC- B7 (IFN-gamma stimulated, Ag pulsed) with Th1 cells stimulated through the T cell receptor (TCR) using anti-CD3 monoclonal antibody (mAb) caused these Th1 cells to proliferate. Furthermore, anti-CD28 and anti-B7 mAbs blocked this response.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutagenesis rescues spermine and Zn2+ potentiation of recombinant NMDA receptors

Alternative splicing generates distinct forms of the NMDA receptor subunit NR1. NR1 subunits with an N-terminal insert (termed N1) form receptors in Xenopus oocytes with greatly reduced potentiation by spermine and Zn2+. Oocytes expressing NR1 receptors with N1 exhibited larger NMDA currents than oocytes expressing corresponding receptors without N1. In the present study, we used mutational analysis to investigate structural features of the N1 insert that control current amplitude and spermine and Zn2+ potentiation. Neutralization of positive charges in N1 rescued spermine and Zn2+ potentiation. Positive charges in N1 did not affect spermine or Zn2+ affinity. Neutralization of positive charges in N1 diminished the responses to the level of NR1 receptors lacking N1. The positively charged N1 may increase NMDA currents by causing a conformational change similar to that produced by spermine and Zn2+ in NR1 receptors lacking N1.

Endothelium dependent vasomotor responses to endogenous agonists are potentiated following ACE inhibition by a bradykinin dependent mechanism

OBJECTIVE

The aim was to investigate the effects of angiotensin converting enzyme inhibition on agonist induced endothelium dependent vasodilatation in vivo.

METHODS

Chronically instrumented conscious dogs (n = 8) were prepared for the measurement of coronary blood flow, diameter of the left circumflex coronary artery, mean arterial blood pressure, and heart rate. Intracoronary infusions of acetylcholine, adenosine, and bradykinin that induced dose dependent increases in coronary blood flow and diameter were performed with and without intracoronary administration of captopril (1 mg.kg-1) and enalapril (0.4 mg.kg-1). The effects were studied of concomitant inhibition of bradykinin actions by the specific B2 kinin antagonist HOE-140 (10(-7) M), NO-synthesis by NG-nitro-L-arginine-methyl ester (L-NAME, 2 x 10(-5) M), or cyclo-oxygenase by indomethacin (10(-7) M) (all intracoronary).

RESULTS

Neither captopril nor enalapril had significant vasodilating effect on the coronary vasculature when given alone. In contrast, both ACE inhibitors potentiated the agonist induced increases in coronary blood flow by bradykinin and acetylcholine (p < or = 0.01). HOE-140 strongly antagonised the effects of infused bradykinin and prevented the potentiation of acetylcholine responses by ACE inhibition. L-NAME caused hypertension and bradycardia and abolished the responses to acetylcholine and adenosine, but only partially attenuated the bradykinin induced increases in coronary blood flow. Simultaneous ACE inhibition reduced the hypertensive effect of L-NAME and partially restored the responses to bradykinin. Indomethacin reduced the responses to bradykinin but did not affect acetylcholine and adenosine induced coronary vasodilatation. The potentiation of the response to acetylcholine induced by ACE inhibition was, however, diminished by indomethacin.

CONCLUSIONS

In the coronary vasculature of the dog, ACE inhibitors enhance vasomotor responses to endothelium dependent agonists by facilitating the release of both NO and PGI2, a mechanism which is coupled to endogenously formed bradykinin. ACE inhibitors may thus mediate their effects in vivo partly by increasing the capacity of the endothelium to release autacoids.

[Cohort study of HIV infection among drug users in Ruili and other counties in Yunnan Province, China]

In 1993, a second survey was conducted in Ruili City and other two counties, where a cohort study field was established last year. Seven hundred and fifty five drug users and one hundred and two spouses of HIV infected IDUs were interviewed. Nine samples among 54 from 89 IDUs in cohort were tested as seroconversion. The seroconversion rate (incidence rate) in IDUs (per hundred person years) in Ruili, Longchuan, and Luxi as well were 40.0, 12.2 and 0, respectively in 1993, comparing to 43.2, 12.2 and 0 in 1992. Thirty eight were tested as positive among 108 samples from 116 newly recruited IDUs. The seroprevalence rates in this three counties were 85.7%, 40.0% and 0 in 1993, comparing to 81.8%, 44.6% and 5.1% in 1992. A coordination of the level between seroconversion and seroprevalence was observed. A increasing trend of seroprevalence among the spouses of HIV positive IDUs was found, the seroprevalence rate were 3.1% in 1990, 9.8% in 1992 and 7.4% in 1993. More attention should be paid to Luxi where the ratio of intravenous drug using increased rapidly, although fewer positives and later starting of drug using was found in this county.

The connexins and their family tree

The connexins, gap junction forming proteins, are encoded by a gene family. Sequence comparisons reveal regions of conservation with functional implications for voltage dependence of junctional conductance, junction formation and regulation by phosphorylation. The best connexin tree shows that most gene duplications giving rise to the family occurred early in or before vertebrate divergence. The topology of most deep branches of the tree is uncertain. Evolutionary rates vary for different paralogous connexin genes.

Induction of nasal and nasopharyngeal tumours in Sprague-Dawley rats fed with Chinese salted fish

Epidemiological studies have implied that Chinese salted fish is a human nasopharyngeal carcinogen. In the present study, 162 Sprague-Dawley rats were randomly assigned to one of four experimental groups. Rats in groups 1 (n = 41) and 3 (n = 40) were exposed to salted fish from birth through the breast feeding period by giving the maternal rats a diet containing 10% and 5% salted fish, respectively, later feeding the rats with pellets containing 10% and 5% of salted fish respectively. In group 2, the rats (n = 41) were given pellets containing 10% of salted fish from 6 weeks of age. Rats in group 4 (n = 40), serving as controls, were only given ordinary pellets. Three rats had nasopharyngeal tumours, 2 from group 1 had a poorly differentiated carcinoma and a squamous cell carcinoma. One rat from group 2 had a squamous cell carcinoma. Four rats had nasal tumours, one fibrosarcoma and one adenocarcinoma were found in rats from group 1. One rhabdomyosarcoma was found in group 2, and one soft tissue sarcoma was found in a rat in group 3. No nasal or nasopharyngeal tumours appeared in the control group. The difference in the occurrence of malignant nasal and nasopharyngeal tumours among the four experimental groups was statistically significant (one tailed p for trend = 0.041). The frequency of tumours appearing in other organs such as the breast, kidney, lung, liver and brain was not significantly different between the salted fish treated groups and the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Epstein-Barr virus infection, salted fish and nasopharyngeal carcinoma. A case-control study in southern China

Two hundred and five histologically confirmed cases of nasopharyngeal carcinoma (NPC) in southern China, and an equal number of matched controls, were investigated for their dietary habits, occupational exposure, use of tobacco and alcohol, history of relatives with NPC, and IgA against Epstein-Barr virus (EBV) capsid antigen (IgA/VCA). Positive IgA/VCA and intake of salted fish were associated with a strong excess risk of NPC. The association persisted after adjustment for other factors. The combination of salted fish and EBV was strongly associated with NPC, and more so than EBV or salted fish per se. Multivariate analyses showed that IgA/VCA was the most important predictor of NPC, and salted fish the second most important. These results suggest that EBV has a strong effect on the development of NPC. The exclusion of EBV and genetic factors in earlier epidemiological studies may have resulted in an overestimation of salted fish as important etiological factor causing NPC.

p53 gene mutations in Chinese human testicular seminoma

Genomic deoxyribonucleic acid from 17 primary human testicular seminomas was screened for the presence of mutations in exons 5 to 8 of gene p53, using the single strand conformation polymorphism assay, followed by direct deoxyribonucleic acid sequencing. The p53 mutations in 1 allele leading to an amino acid change but a normal (wild-type) sequence in the remaining allele were identified in 4 of 17 seminomas (23.5%). Sites of mutations were in exon 5 (codon 141), exon 7 (codon 238, codon 258) and exon 8 (codon 270). The present study suggested that mutation of the p53 gene is involved in the development of human testicular seminoma as in the case of several other types of human cancers.

Structural variations and phenotypic switching of mycoplasmal antigens

It is becoming apparent that a high rate of variability of surface structures is a ubiquitous property among mycoplasmas. The present study demonstrates how variations in the size of the V-1 antigen (a major surface antigen of Mycoplasma pulmonis thought to be associated with virulence) are reflected by phenotypic differences (cytadherence) that may play a role in virulence of the organism. Furthermore, a similar antigen is described for the human pathogen Urea-plasma urealyticum, and data are presented on the analysis of clinical isolates that demonstrate the potential for variation in the size of this antigen in vivo. Although no direct connection of antigen variation to natural disease has yet been presented, the data further document the tremendous potential for virulence-related diversity possessed by these organisms and emphasize the importance of a valid animal model for discerning the true relationship between variation and virulence.

Plasma levels of cyclic nucleotides in chronic congestive heart failure and their clinical implication

Plasma levels of cyclic nucleotides were determined by radioimmunoassay in 196 cardiac patients and 50 normal persons. Plasma levels of cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) increased with the deterioration of cardiac function. The level of cGMP was correlated with the cardiothoracic ratio, ratio of pre-ejection period and left ventricular ejection time, the intracardiac diameter, left ventricular ejection fraction and left ventricular short axis shortening (r = 0.55, r = 0.50, r = 0.55, r = -0.53 and r = -0.50, respectively; P < 0.001). There were only weak correlations between the level of cAMP and the cardiothoracic ratio, the ratio of pre-ejection period and the left ventricular ejection time, left ventricular ejection fraction, and left ventricular short axis shortening (r = 0.35, r = 0.38, r = -0.28 and r = -0.31, respectively; P < 0.01). The correlations between cGMP and mean pulmonary artery pressure (r = 0.48; P < 0.05) and mean left atrial pressure (r = 0.55; P < 0.01) were also significant. In patients who had received cardioversion and valve replacement the plasma cGMP level decreased significantly. During the follow-up period, 29 of 108 patients died (26.9%), the initial plasma levels of cAMP and cGMP in the dead group were significantly higher than those in the survival group (27.41 +/- 1.13 and 31.11 +/- 3.33 vs. 21.56 +/- 0.60 and 17.45 +/- 1.05 nmol/l, respectively; P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)