Non-invasive detection of endothelial dysfunction in patients with essential hypertension

The endothelium regulates vascular tone through the release of vasoactive agents that act on the underlying vascular smooth muscle. This endothelial function is impaired in certain cardiovascular conditions including atherosclerosis, and hypercholesterolemia. However, in patients with essential hypertension it is unclear whether endothelium-dependent vasodilation is impaired. Using high-resolution ultrasound, we measured the diameter of the brachial arteries at rest, during reactive hyperaemia (with increase flow causing endothelium-dependent dilatation), and after sublingual glyceryl trinitrate (GTN; causing endothelium-independent dilatation) in 42 subjects, consisted of 21 controls with normal blood pressure [mean(SD) arterial blood pressure, 92+/-7 mmHg] and 21 patients with established essential hypertension (mean arterial blood pressure, 123+/-12 mmHg). The results showed that in patients with essential hypertension, flow-mediated dilatation in arteries was much reduced in comparison with the control group (4.6%+/-2.8% vs. 12.4%+/-2.9%, P<0.001). However, there was no significant difference in response to GTN between the two groups (19.8%+/-6.0% vs. 24.5%+/-10.2%, P=0.186). This indicates that endothelium-dependent vasodilation is impaired in patients with essential hypertension.

Adenylyl cyclase and G protein receptor kinase expression during development of heart failure

We examined alterations in left ventricular (LV) G protein receptor kinase (GRK) and adenylyl cyclase (AC) isoform expression during the development of pacing-induced congestive heart failure (CHF). AC isoform and GRK expression were assessed 4 (mild CHF) and 28 (severe CHF) days after initiation of pacing. LV beta-adrenergic receptor (beta-AR) number and G protein content were unchanged by mild CHF. LV AC isoform mRNA content was unaltered by mild CHF, but there were increases in total GRK activity (P < 0.01), total GRK5 protein content (P < 0.04), and GRK5 mRNA (P = 0.003); total GRK2 protein content and GRK2 mRNA were unchanged. Mild CHF was associated with decreased beta-AR coupling (P < 0.01) and reduced beta-AR stimulation of AC (P < 0.05). Severe CHF was associated with LV beta-AR downregulation (P = 0.0001) and uncoupling (P < 0.001) and marked generalized reduction of AC activity (mean P = 0.01). LV ACVI isoform mRNA content was reduced (P = 0.002), but ACII and ACV isoform mRNA contents were unaffected. Persistent elevations in LV total GRK activity (P < 0.01), total GRK5 protein content (P < 0.001), and GRK5 mRNA (P = 0.01) were found; in contrast, total GRK2 protein content was unchanged and GRK2 mRNA was reduced (P = 0.02). These studies indicate that increased GRK activity is an early charge in heart failure that predates alterations in AC isoform expression. Impaired hormonal stimulation of AC, associated with beta-AR uncoupling, may result from increased GRK5 expression. AC downregulation is isoform specific and accompanies severe but not mild CHF.

CDO: an oncogene-, serum-, and anchorage-regulated member of the Ig/fibronectin type III repeat family

Cell adhesion molecules of the Ig superfamily are implicated in a wide variety of biological processes, including cell migration, axon guidance and fasciculation, and growth control and tumorigenesis. Expression of these proteins can be highly dynamic and cell type specific, but little is known of the signals that regulate such specificity. Reported here is the molecular cloning and characterization of rat CDO, a novel cell surface glycoprotein of the Ig superfamily that contains five Ig-like repeats, followed by three fibronectin type III-like repeats in its extracellular region, and a 256-amino acid intracellular region that does not resemble other known proteins. In rat embryo fibroblasts, cdo mRNA expression is maximal in confluent, quiescent cells. It is rapidly and transiently down-regulated by serum stimulation of such cells, and is constitutively down-regulated in oncogene-transformed derivatives of these cells. CDO protein levels are also dramatically regulated by cell-substratum adhesion, via a mechanism that is independent of cdo mRNA expression. The amount of CDO produced at the surface of a cell may therefore be governed by a complex balance of signals, including mitogenic stimuli that regulate cdo mRNA levels, and substratum-derived signals that regulate CDO protein production. cdo mRNA is expressed at low levels in most adult rat tissues. A closely related human gene maps to chromosome 11q23-24, a region that displays frequent loss of heterozygosity in human lung, breast, and ovarian tumors. Taken together, these data suggest that loss of CDO function could play a role in oncogenesis.

Capillary geometry in the soleus muscle of rats cold-acclimatized for 68 generations

The effects of chronic cold exposure on soleus muscle capillarity were examined, particularly in terms of the distribution of arteriolar and venular capillaries and their capillary domain area (CDA) in adult rats exposed to cold for 68 generations (CG; n = 6). These parameters were compared with those obtained from control rats (CON; n = 5) and deacclimatized rats (DCG; n = 4), reared in thermoneutral temperature after being reared for 11 generations in cold. Morphometric data were obtained from muscle cross sections exposed to a double-staining method that stained the arteriolar and venular portions of capillaries blue and red, respectively. In CG, the capillary densities of arteriolar and venular capillaries were significantly greater than that of both CON and DCG (P < 0.05). The CDA of arteriolar, intermediate and venular portions in CG was significantly smaller by 15, 14 and 13%, respectively, than those of respective portions in CON (P < 0.05). Although CDA of arteriolar and venular capillary portions was also smaller in DCG than in CON, the degree of reduction was less in DCG than in CG. The succinate dehydrogenase activity of soleus muscle was significantly greater in CG than in both CON and DCG (P < 0.05). These results suggest that adaptive changes in the oxygen transport system, identified as an increase in the number of arteriolar capillaries and a reduction in the diffusion distance for oxygen, were observed in the soleus muscle after chronic cold exposure. These changes may improve the effective oxygen supply to muscle tissues and enable muscle tissues to promote thermogenesis in the cold atmosphere.

Remodeling of capillary network in left ventricular subendocardial tissues induced by intravenous vasopressin administration

OBJECTIVE

The question of whether the coronary vasospasm induced by intravenous administration of vasopressin produces any remodeling of the capillary network in the left ventricle was investigated. To this end, cardiac tissues obtained from vasopressin-injected rats were stained to allow capillary counting and for basic fibroblast growth factor (bFGF).

METHODS

Nine male Donryu rats were divided into three groups that received, respectively, 0.25 ml of saline containing 0, 0.5, or 1.0 U/kg vasopressin injected into the tail vein once daily for 4 days. Rats were killed 30 days after the last injection. Two additional rats each received a single intravenous injection of 1.0 U/kg vasopressin and were killed 24 hours later. The left ventricles were removed and 16- or 10-micron frozen sections were cut for differential staining and distribution of bFGF, respectively. Differential staining was used to classify the capillary portions, and bFGF was identified by immunohistological staining.

RESULTS

Compared with the control group, total capillary density was increased in both vasopressin-treated groups, capillary to myocyte ratio was increased, and the capillary domain areas decreased in the three capillary portions. Arteriolar and intermediate capillary portions increased, while the venular capillary portion decreased. In rats killed 24 hours after vasopressin injection, a considerable amount of bFGF could be demonstrated immunohistochemically in the ventricular tissues, and the punctate distribution of bFGF was still found in rats killed 30 days after treatment.

CONCLUSIONS

A remodeling of capillary network which would increase the oxygen transport capacity to cardiac tissues was produced in left ventricular tissues by intravenous injection of vasopressin. bFGF located around capillaries and in the interstitial space may have been involved in the capillary remodeling.

Independent genetic control of maize starch-branching enzymes IIa and IIb. Isolation and characterization of a Sbe2a cDNA

In maize (Zea mays L.) three isoforms of starch-branching enzyme (SBEI, SBEIIa, and SBEIIb) are involved in the synthesis of amylopectin, the branched component of starch. To isolate a cDNA encoding SBEIIa, degenerate oligonucleotides based on domains highly conserved in Sbe2 family members were used to amplify Sbe2-family cDNA from tissues lacking SBEIIb activity. The predicted amino acid sequence of Sbe2a cDNA matches the N-terminal sequence of SBEIIa protein purified from maize endosperm. The size of the mature protein deduced from the cDNA also matches that of SBEIIa. Features of the predicted protein are most similar to members of the SBEII family; however, it differs from maize SBEIIb in having a 49-amino acid N-terminal extension and a region of substantial sequence divergence. Sbe2a mRNA levels are 10-fold higher in embryonic than in endosperm tissue, and are much lower than Sbe2b in both tissues. Unlike Sbe2b, Sbe2a-hybridizing mRNA accumulates in leaf and other vegetative tissues, consistent with the known distribution of SBEIIa and SBEIIb activities.

The capillarity of the subendocardium of left ventricle in rats reared at a low temperature for many generations

The cardiac capillarity in adult rats reared at 5 degrees C for 68 generations was studied with a double staining method of alkaline phosphatase and dipeptidylpeptidase IV. Capillary density, proportions of arteriolar, intermediate and venular capillary portions and capillary domain area were measured in the left ventricular wall. Compared with the control rats which had been brought back from the low temperature at the 12th generation and reared at 25 degrees C since then, the heart and the cardiac cells were hypertrophied, total capillary density increased and the capillary domain areas were reduced along the capillary path from the arteriolar to venular capillary portions. The number of the venular capillary portions showed no significant change but the arteriolar and intermediate capillary portions significantly increased. All these changes suggest that the cardiac capillary network was better developed in the cold-reared rats than in control rats. In the cold-adapted rats the hypertrophic changes in cardiac cells are thus accompanied by improvements in the oxygen delivery capacity. This adaptation provides a basis for the maintenance of increased thermogenesis in many organs. The changes cannot be established by several weeks exposure to low temperature, but only after rats have been bred in a cold room for generations.

A functional polymorphism in the promoter region of the dopamine D2 receptor gene is associated with schizophrenia

An excess dopaminergic activity may be implicated in the etiology of schizophrenia. Our objective was to identify nucleotide variants in the 5' region of the dopamine D2 receptor gene (DRD2) and to clarify their effects on schizophrenia. We identified two polymorphisms, the A-241G and -141C Ins/Del, by examination of 259 bp in the 5'-flanking region and 249 bp of exon 1 of DRD2. Reporter constructs containing the -141C Del allele cloned into a luciferase reporter plasmid drove 21% (Y-79 cells) and 43% (293 cells) expression compared with the -141C Ins allele. In a case-control study, the -141C Del allele frequency was significantly lower in 260 schizophrenic patients than in 312 controls (OR = 0.60, 95%CI 0.44-0.81, P < 0.001). No significant association was found between the A-241G polymorphism and in vitro luciferase activity, or in allele frequency between the patients versus controls. These findings show that the -141C Ins/Del may be a functional polymorphism in the 5'-promoter region of DRD2 and may affect the susceptibility to schizophrenia.

[Mechanical ventilation therapy with permissive hypercapnia on ARDS]

OBJECTIVE

Study of mechanical ventilation (MV) therapy of ARDS (acute respiratory distress syndrome).

METHODS

Ten cases of ARDS were observed. Depending on patients' kidney compensation for respiratory acidosis, low tidal volume (VT, mean = 6.5 ml/kg) was used and certain respiratory acidosis was permitted in order to decrease airway plateau pressure and lung barotrauma. On the premise of keeping patients' PaO2 about 7.3 kPa (1 kPa = 7.5 mmHg), lowest possible FiO2 (mean = 0.51) and PEEP (mean = 0.92 kPa, 1 kPa = 10.2 cmH2O) were used.

RESULTS

Seven of the ten survived. Three of them had respiratory acidosis and two had lung barotrauma during MV.

CONCLUSION

Using lower VT and permitting certain respiratory acidosis are worthy to be considered in MV therapy of ARDS.

[Arterialization of the capillary network in the left ventricular subendocardium in young rats subjected to exercise training]

The increase in cardiac activity requires an increase in oxygen supply to the ventricular tissues. Two adaptational changes in the capillary network seem to increase the oxygen supply; one is the increase in capillary density and the other may be the increase in arteriolar capillaries. To test this hypothesis, double staining method, which was validated by microsphere injection, was used for differentiation of arteriolar and venular capillaries in exercise-trained rats in the present study. Male Wistar rats after weaning (3 weeks old) were subjected to treadmill running 1 hour/day in the evening, 6 days/week. The running speed was increased from 10 m/min without gradient to 25 m/min with a 7% gradient for 6 weeks. The total capillary density and capillary to myocyte ratio increased significantly. Capillary domain area decreased, suggesting neoformation of capillaries. In support of the capillary increase two stimulators for angiogenesis, vascular endothelial growth factor and basic fibroblast growth factor were immunohistochemically stained in the ventricular tissues from exercise-trained rats. Capillary of arteriolar type increased with a decrease in the venular capillary. The arteriolar portion of capillaries became significantly longer and the venular portion shorter than in resting control rats. Branching of capillaries increased both in the arteriolar and venular portions. These results suggest that the arterialization of capillary network proceeded with the increase in the capillary density to facilitate the oxygen transport to cardiac tissues.

The capillarity of left ventricular tissue of rats subjected to coronary artery occlusion

OBJECTIVE

The effects of chronic coronary occlusion on the capillarity of left ventricular tissue in rat heart.

METHODS

The heart was exposed through a left-sided thoracotomy in ethylether-anesthetized and ventilated rats. The left coronary artery was occluded with a thin suture and the thorax was closed. Thirty days after the surgery the heart was removed and cross-sections were made for morphometric analyses.

RESULTS

The cross-sectional area of cardiomyocytes increased markedly in the subepi- and subendocardia with a concomitant increase in the capillary to myocyte ratio. The total capillary density increased in the non-ischemic zone. The balance between the increase in capillary density and myocyte hypertrophy was assessed from the capillary domain area (CDA). CDAs were significantly smaller for the venular capillary portion in the subendocardial non-ischemic zone. However, CDAs in the transition zone around the necrosis were significantly increased in the venular capillary portion in the subendocardium and in all capillary portions in the subepicardium compared with those in the non-ischemic zone. Immunohistological staining for basic fibroblast growth factor (bFGF) revealed punctate bFGF distribution in both the non-ischemic and transition zones of ventricular tissues 30 days after occlusion, suggesting a persistent stimulation for capillary angiogenesis.

CONCLUSION

The remodelling of the capillary bed is not uniform throughout the cardiac tissue in coronary-occluded rat hearts. CDAs decreased in the non-ischemic zone but increased in the transition zone. The rate of capillary angiogenesis failed to parallel the development of hypertrophy in the transition zone over 30 days, as could be seen from the significant reduction in the percentage of venular capillary portions.

Effects of treadmill training on the arteriolar and venular portions of capillary in soleus muscle of young and middle-aged rats

The effects of a 6-week programme of endurance training on soleus muscle capillarity were examined, in terms particularly of the proportions of arteriolar and venular capillaries and their capillary domain area, in young (3-week-old) and middle-aged (54-week-old) Wistar rats. Exercise protocols for the young training group were: 10-22.5 m min-1 60 min day-1 for 6 days a week, with a gradient of 7 degrees during the final 2 weeks; for the middle-aged training group, the protocols were: 10-20 m min-1. 50 min day-1 for 6 days a week. In both young and middle-aged training groups, the density of arteriolar capillaries was significantly increased (P < 0.05), but that of venular and intermediate capillaries was decreased slightly. The proportion of arteriolar capillaries therefore was significantly (P < 0.05) increased, from 63.9 to 73.1% in young rats and from 33.0 to 48.4%, in middle-aged rats after training. The increase in the proportion of arteriolar capillaries is an advantageous adaptation to exercise-induced increases in oxygen demand. In both young and middle-aged rats, capillary domain area and Krogh's tissue cylinder radii in all capillary portions decreased after training. These results suggest that adaptive changes in oxygen transport system, identified as an increase in the arteriolar capillary and a reduction in diffusion distance for oxygen, were observed in middle-aged as well as in young rats. However, capillary angiogenesis induced by exercise appeared to be greater in young than in middle-aged rats.

Na, an autoproteolytic product of the herpes simplex virus type 1 protease, can functionally substitute for the assembly protein ICP35

The herpes simplex virus type 1 (HSV-1) protease and its substrate, the assembly protein ICP35, are involved in virion maturation. Both proteins are encoded by a single open reading frame but are translated independently from 3'-coterminal mRNAs of different sizes and are in frame. The herpesvirus shell assembles around an internal scaffold which is subsequently lost during packaging of the viral genome. The scaffold is composed of ICP35, which is the major component, and autoproteolytically processed forms of the viral protease containing sequences common to ICP35 (Nb). In the baculovirus system, HSV-1 intact capsids can be formed in the presence of the protease or ICP35, indicating that the protease may substitute for ICP35 (Thomsen et al., J. Virol. 68:2442-2457, 1994). This is further supported by the fact that ICP35, in contrast to the protease, is not absolutely essential for viral growth. The processed intermediate of the protease analogous to ICP35 is the 388-amino-acid (aa) protein, Na, which is an N-terminal 59-aa extension of the 329-aa ICP35. To directly examine whether Na can functionally substitute for ICP35 during viral replication, we first constructed a mutant virus, Na delta35, in which 35 aa from the N terminus of Na were deleted. Phenotypic analysis of the mutant showed that this deletion had no effect on protease function. The function of Na was further examined by construction of a plasmid expressing Na alone and testing its ability to complement the growth of the mutant Prb virus in the absence of ICP35. Our results demonstrate that Na can functionally substitute for ICP35 during viral replication.

Contribution to the regulation of virus replication in cells latently infected with human immunodeficiency virus 1

Monocytes/macrophages have been known to play an important role in the initiation and propagation of human immunodeficiency virus 1 (HIV-1) infection. To analyze the function of these cells during the clinical asymptomatic period of infection, we examined the effect of murine peritoneal macrophages and human peripheral blood macrophages on two cell lines latently infected with HIV-1, a promonocytic cell line, U1, and a T-cell line, ACH-2. Monokines of the murine peritoneal macrophages induced significant viral expression in U1, but not in ACH-2 cells. Experiments employing transient transfection of U937 and CEM cells with HIV long terminal repeat (LTR)-chloramphenicol acetyl transferase (CAT) plasmids indicated that the effect of these monokines was due to specific activation of the HIV LTR. In contrast, supernatants of human macrophages induced viral expression in both ACH-2 and U1 cells. These results suggest that several monokines are active in regulating the transition from the clinical asymptomatic period of HIV infection to progression to acquired immunodeficiency syndrome (AIDS).

Different enzyme activities in coronary capillary endothelial cells

Differential distributions of alkaline phosphatase (AP) and dipeptydylpeptidase IV (DPPIV) were studied in coronary microvascular endothelial cells. Endothelial cells were obtained by the perfusion of coronary vessels with 0.1% trypsin PBS solution and cultured in uncoated culture dishes. Staining of cultured endothelial cells with AP- and DPPIV-sensitive reagents revealed blue or red staining, respectively. Most colonies showed cells of only one color, blue or red, even at the fifth passage. AP-sensitive cells, which were originally elongated, shortened and widened, proliferating to form monolayer colonies of cobble stone-like cells. AP-stainability became weak with repeated passages. DPPIV-sensitive endothelial cells remained elongated even after repeated passages. The cell shape and stainability seemed to be coupled and maintained through the five passages studied.

Myocyte hypertrophy and capillarization in spontaneously hypertensive stroke-prone rats

Stroke-prone spontaneously hypertensive rats (SHRSP) are liable to suffer a stroke between 25 and 40 weeks of age. Left ventricular capillarity was studied in 40-week-old SHRSP to clarify the effects of hypertrophic changes in cardiomyocytes on oxygen transport capacity within the tissue. The innermost region of the left ventricular subendocardium at the level of the maximum diameter of the heart was investigated. Methods for sectioning and differential staining of arteriolar, intermediate and venular capillaries, and measurements for determining capillarity parameters were as previously described. Total capillary density decreased, while capillary domain areas increased along the whole capillary pathway. These changes in SHRSP seemed unfavorable for oxygen supply to ventricular tissues. To minimize the effects of the adverse changes, the ratio of the capillary to myocyte number increased markedly. The proportion of arteriolar capillaries increased and the venular proportion decreased.

Reconstitution of ATP-dependent leukotriene C4 transport by Co-expression of both half-molecules of human multidrug resistance protein in insect cells

Multidrug resistance protein (MRP) confers a multidrug resistance phenotype similar to that associated with overexpression of P-glycoprotein. Unlike P-glycoprotein, MRP has also been shown to be a primary active ATP-dependent transporter of conjugated organic anions. The mechanism(s) by which MRP transports these compounds and increases resistance to natural product drugs is unknown. To facilitate studies on the structure and function of MRP, we have determined whether a baculovirus expression system can be used to produce active protein. Full-length MRP as well as molecules corresponding to either the NH2- or COOH-proximal halves of the protein were expressed individually and in combination in Spodoptera frugiperda Sf21 cells. High levels of intact and half-length proteins were detected in membrane vesicles from infected cells. Although underglycosylated, the full-length protein transported leukotriene C4 (LTC4) with kinetic parameters very similar to those of MRP produced in transfected HeLa cells. Neither half-molecule was able to transport LTC4. However, a functional transporter with characteristics similar to those of intact protein could be reconstituted when both half-molecules were co-expressed. Transport of LTC4 by Sf21 membrane vesicles containing either intact or reconstituted MRP was competitively inhibited by both S-decylglutathione and 17beta-estradiol 17-(beta-D-glucuronide), with Ki values similar to those reported previously for MRP expressed in HeLa cells (Loe, D. W., Almquist, K. C., Deeley, R. G., and Cole, S. P. C. (1996) J. Biol. Chem. 271, 9675-9682; Loe, D. W., Almquist, K. C., Cole, S. P. C., and Deeley, R. G. (1996) J. Biol. Chem. 271, 9683-9689). These studies demonstrate that human MRP produced in insect cells can function as an active transporter of LTC4 and that the NH2- and COOH-proximal halves of the protein can assemble efficiently to form a transporter with functional characteristics similar to those of the intact protein.

Differential and antagonistic effects of v-Jun and c-Jun

We compared the ability of cellular and viral Jun (c-Jun and v-Jun) to transactivate target genes. c-Jun and v-Jun bind specifically to 12-O-tetradecanoylphorbol-13-acetate responsive elements [TREs, also called activator protein 1 (AP-1) motifs]. However, whereas c-Jun activates TRE-controlled promoters, v-Jun represses them. Cotransfection of the two Jun proteins reduces c-Jun-dependent transactivation. The expression of the endogenous c-jun gene, regulated through a promoter-proximal AP-1-binding site, is repressed in v-Jun-transformed chicken embryo fibroblasts. It is suggested that an M(r) 18,000 v-Jun peptide prominent in v-Jun-transformed cells acts as a transdominant-negative regulator of AP-1 activity and of c-jun expression. In contrast to the results with TRE sites, both v-Jun and c-Jun activate transcription through the human T-cell leukemia virus type I 21-bp repeat which contains a sequence homologous to the cyclic AMP responsive element. However, full-length Jun proteins bind to this site only with low affinity, and binding of the truncated v-Jun was barely detectable. These observations show that the oncogenic viral form of Jun differs from the cellular version in promoter preference and on certain promoters acts as an antagonist to c-Jun.

Neutralization of human immunodeficiency virus type 1 (HIV-1) with antibody from carriers' plasma against HIV-1 protein p17

It was investigated whether human antibody against HIV-1 protein p17 (anti-p17) in HIV carriers' plasma has the ability to neutralize the infectivity of HIV. By the pretreatment of HIV-1 with anti-p17 from HIV carriers, progeny HIV-1 production from cells infected with virus pretreated with anti-p17 was suppressed and/or delayed. The neutralizing activity of anti-p17 was decreased in the presence of recombinant p17. The latter obviously masked the neutralizing activity of anti-p17. The relevant epitope(s) on p17 is located apparently on the surface of HIV virions and the binding of anti-p17 to p17 impairs the infectivity of HIV. This implies that anti-p17, if stably present in HIV carriers' plasma, may also play an important role in reducing the infectivity of HIV-1 in vivo.