Effects of acute AT1 receptor blockade by candesartan on arterial pressure and renal function in rats

Experiments were performed on normal anesthetized rats to determine the effects of candesartan, a novel AT1 receptor antagonist, on the arterial pressure and renal hemodynamic responses to bolus doses of angiotensin II (ANG II) and on renal hemodynamics and sodium excretion. Control arterial pressure responses to bolus ANG II doses of 10, 50, 100 and 1,000 ng were 26 +/- 6, 54 +/- 7, 57 +/- 7, and 79 +/- 7 mmHg; the decreases in cortical renal blood flow (CRBF), measured with laser-Doppler flowmetry, were 47 +/- 9, 64 +/- 8, 71 +/- 6, and 82 +/- 6%. The vasoconstrictor responses to ANG II up to 1,000 ng were completely blocked by candesartan doses of 1 and 0.1 mg/kg, whereas treatment with 0.01 mg/kg candesartan attenuated the arterial pressure and CRBF responses. The higher doses of candesartan (1 and 0.1 mg/kg) elicited rapid decreases in arterial pressure, leading to associated decreases in sodium excretion. Renal blood flow (RBF), glomerular filtration rate (GFR), and urine flow also decreased following treatment with candesartan at 1 mg/kg. In contrast, when candesartan was given at 0.01 mg/kg, which did not decrease arterial pressure significantly, there were significant increases in GFR (16 +/- 4), RBF (9 +/- 2), urine flow (11 +/- 2), sodium excretion (35 +/- 7), and fractional sodium excretion (39 +/- 8%). The inability to overcome blockade, even with very high ANG II doses, indicates that candesartan is a potent noncompetitive blocker of ANG II pressor and renal vasoconstrictor effects. The lower candesartan dose that did not cause significant hypotension elicited substantial increases in RBF, GFR, and sodium excretion, revealing the direct renal vasodilator and natriuretic effects of AT1 receptor blockade.

Renoprotective effects of nitric oxide in angiotensin II-induced hypertension in the rat

Experiments were performed in anesthetized male Sprague-Dawley rats to determine whether increased nitric oxide (NO) activity during the development of hypertension exerts a protective effect on renal cortical blood flow (CBF) and medullary blood flow (MBF). The effects of acute NO synthase inhibition on renal function and on CBF and MBF, measured by laser-Doppler flow probes, were evaluated in control and ANG II-infused hypertensive rats, prepared by the infusion of ANG II at a rate of 65 ng/min via osmotic minipumps implanted subcutaneously for 13 days. In normotensive rats (n = 8), intravenous infusion of N omega-nitro-L-arginine (NLA; 20 micrograms.100 g-1.min-1) decreased CBF by 21 +/- 4% and MBF by 49 +/- 8% and increased blood pressure from 118 +/- 1 to 140 +/- 2 mmHg. In ANG II-infused rats (n = 7), CBF and MBF decreased by 46 +/- 5% and 25 +/- 6%, respectively, during infusion of NLA. Arterial pressure increased from 160 +/- 5 to 197 +/- 7 mmHg, which was a greater absolute increase than in normotensive controls. Basal renal blood flow (RBF), estimated from p-aminohippurate clearance and hematocrit, was similar in both the control (6.0 +/- 0.5 ml.min-1.g-1) and hypertensive (6.0 +/- 0.6 ml.min-1.g-1) rats. However, NLA-induced reductions in RBF averaged 60 +/- 5% in the hypertensive rats, compared with 31 +/- 9% observed in control rats. GFR in control (0.97 +/- 0.03 ml.min-1.g-1) and hypertensive rats (0.78 +/- 0.12 ml.min-1.g-1) decreased to a similar extent during the first 30-min period of NLA infusion. GFR returned toward control levels in control rats; in contrast, GFR remained significantly decreased in the ANG II-infused rats (0.58 +/- 0.11 ml.min-1.g-1). Basal urinary sodium excretion (0.2 +/- 0.08 mueq.min-1.g-1), fractional excretion of sodium (0.3 +/- 0.13%), and urine flow (4.9 +/- 0.39 microliters.min-1.g-1) in hypertensive rats did not increase significantly after NLA treatment as occurred in normotensive controls. These data suggest that a compensatory increase in nitric oxide activity partially counteracts the vasoconstrictor influence of elevated ANG II levels to regulate renal hemodynamics and maintain cortical perfusion in the renal circulation.

Survey of Theileria parasite infection in cattle in Taiwan

An survey of Theileria parasite infection in cattle in Taiwan was carried out by polymerase chain reaction (PCR). A total of 491 blood samples, 105 from southern area and 386 from northern area, were collected from bovine in 16 different farms. From northern area, Theileria piroplasms could be seen in only 4 of 105 blood samples microscopically. However, when p32/34 genes (encoding immunodominant piroplasm surface proteins) were amplified by PCR, 15 blood samples were detected positive. They were analyzed by using allele-specific primers of 3 allelic forms of p32/34 and all contained C type of T. sergenti. Four blood samples were found infected with both C and B (T. buffeli) type parasites. Examination of 386 blood samples from southern area of Taiwan did not reveal any Theileria parasite microscopically, as well as by PCR amplification.

Two tandemly repeated telomere-associated sequences in Nicotiana plumbaginifolia

Two tandemly repeated telomere-associated sequences, NP3R and NP4R, have been isolated from Nicotiana plumbaginifolia. The length of a repeating unit for NP3R and NP4R is 165 and 180 nucleotides respectively. The abundance of NP3R, NP4R and telomeric repeats is, respectively, 8.4 x 10(4), 6 x 10(3) and 1.5 x 10(6) copies per haploid genome of N. plumbaginifolia. Fluorescence in situ hybridization revealed that NP3R is located at the ends and/or in interstitial regions of all 10 chromosomes and NP4R on the terminal regions of three chromosomes in the haploid genome of N. plumbaginifolia. Sequence homology search revealed that not only are NP3R and NP4R homologous to HRS60 and GRS, respectively, two tandem repeats isolated from N. tabacum, but that NP3R and NP4R are also related to each other, suggesting that they originated from a common ancestral sequence. The role of these repeated sequences in chromosome healing is discussed based on the observation that two to three copies of a telomere-similar sequence were present in each repeating unit of NP3R and NP4R.

Generation of infectious virus particles by transient co-expression of human immunodeficiency virus type 1 gag mutants

We have demonstrated that COS7 cells transiently co-expressing myristylation-defective (Myr-) and protease-defective (PR-) human immunodeficiency virus (HIV) mutants can release infectious virions when co-transfected with an amphotropic murine leukaemia virus envelope protein expression plasmid (SV-A-MLV-env). In contrast, no infectious virions were detected when a PR-, noninfectious HIV gag mutant was co-expressed with the Myr- mutant, although the Myr- mutant could still process the immature core particles in trans. This result indicates that generation of functionally normal Gag proteins is required for virus infectivity in our complementation system. A mutant with a 56-amino-acid deletion in the N-terminal region of the capsid (CA) domain could still complement the PR- mutant to generate infectious virions, suggesting that the deletion mutant could provide a functional protease for processing in the PR- mutant. This result is consistent with the concept that mutations within the N-terminal region of the CA domain have no major effects on Gag-Pol incorporation into particles.

Intrarenal production of angiotensin II

The intrarenal renin-angiotensin system plays a critical role in the paracrine regulation of renal hemodynamics and tubular transport function. Much of the intrarenal angiotensin II (ANG II) is formed locally as evidenced by intrarenal ANG II contents that are much greater than can be explained from the circulating ANG II concentration. Intrarenal ANG II is formed from systemically delivered ANG I and from intrarenally formed ANG I derived from systemically delivered angiotensinogen as well as locally synthesized angiotensionogen. There is a regional distribution of intrarenal ANG II in that the medullary content per gram of tissue is four to five times higher than the cortical content. In addition, most of the cortical ANG II is compartmentalized in the renal interstitial fluid and in the tubular fluid. Proximal tubule cells contain all the components of the renin-angiotensin system necessary for synthesis and secretion of ANG II. Proximal tubule concentrations of ANG II as well as ANG I and angiotensinogen support the concept that the proximal tubule cells secrete ANG II or precursors of ANG II into the tubular fluid. The intratubular concentrations of ANG II are in the nanomolar range, indicating a substantial capability to influence luminal ANG II receptors on the tubule cell membranes. Thus, much of the ANG II-dependent actions on tubular transport functions could be due to specific effects of locally synthesized ANG II on luminal ANG II receptors. Experimental evidence shows that the intratubular ANG II concentrations are regulated independently of the circulating concentrations, but the specific mechanisms responsible remain to be delineated.

Renal responses to AT1 blockade in angiotensin II-induced hypertensive rats

Previous studies have shown that uninephrectomized rats infused chronically with low doses of angiotensin II (Ang II) develop progressive hypertension that is prevented by coadministration of losartan in the drinking water. The present study was performed to contrast the effects of chronic and acute losartan treatment in reversing the Ang II-mediated actions on arterial pressure and renal function. Ang II was infused subcutaneously via osmotic minipumps (40 ng/min) for 13 days in two groups (N = 10 and N = 6); one group also received losartan in the drinking water (30 mg/kg.day) throughout this period. Untreated rats (N = 6) and rats (N = 6) receiving only losartan served as control groups. Ang II-infused rats had higher mean arterial pressures (153 +/- 7 versus 107 +/- 3 mm Hg) and lower GFR (0.7 +/- 0.04 versus 0.98 +/- 0.06 mL/min.g) than Ang II-infused rats receiving losartan chronically. The Ang II-infused rats responded to acute doses of losartan (10 mg/kg) with progressive reductions in arterial pressure and significant increases in cortical blood flow (34 +/- 12% increase), renal plasma flow, GFR, and sodium excretion; however, the increases in renal blood flow and GFR were not sustained as systemic arterial pressure decreased. Because Ang II-infused rats receiving losartan chronically still exhibited decreases in RBF in response to a bolus dose of Ang II, further studies evaluated the effects of acute losartan treatment in rats treated chronically with losartan. Although arterial pressure decreased only slightly, demonstrating adequate systemic vascular blockade, there were still substantial and sustained increases in renal plasma flow, cortical blood flow (20 +/- 4% increase), GFR, and sodium excretion. In summary, the modest responses to acute losartan in Ang II-infused rats indicate that chronic Ang II infusions lead to alterations in renal function that are only partially reversible by acute losartan treatment. In contrast, chronic treatment with losartan prevents the Ang II-induced decrease in GFR. The renal responses to acute losartan in the Ang II-infused rats treated chronically with losartan suggest that substantive intrarenal actions of Ang II can be maintained even when the systemic vascular AT1 receptors are effectively blocked.

Sequences and comparisons of duck mitochondrial DNA control regions

In this study, the nucleotide sequences of the displacement loop (D-loop) and the ribosomal RNA genes of mitochondrial DNA (mtDNA) were determined from a representative each of two genera of ducks, Cainina muschata and Anas platyrhynchos. The duck mtDNA shows a specific gene order at 5' upstream of D-loop (5'ND6-tRNA(Glu)-D-loop3') that is identical to chick mtDNA but is different from that of mammalian or amphibian (5' cytochrome b-tRNA(Thr)-tRNA(Pro)-D-loop3'). Nucleotide diversity is greatest in the D-loop while being most conserved in the 12S rRNA gene, as indicated from a sequence comparison between duck and chick mtDNA. A consensus sequence in the D-loop region, which may play influential roles in the regulation of transcription and replication of mtDNA, was found in both CSB-1 and repeated sequences of birds. Sequences of four tRNA genes in this region are also reported. Among them, tRNA(Glu) shows the greatest sequence divergence when different order of birds are compared.

Clinical and hematological characteristics of hepatosplenic T gamma/delta lymphoma with isochromosome for long arm of chromosome 7

Hepatosplenic T gamma/delta lymphoma is a rare entity of peripheral T cell lymphoma. Three of 386 patients with non-Hodgkin's lymphoma in our institute were found to have this subtype of lymphoma. All had chromosomal abnormalities of isochromosome 7q and trisomy 8. The clinical and hematological features of these three patients are reported. All were males with ages ranging from 23 to 29 years. Initial presentation comprised purpura and variable degree of hepatosplenomegaly. None had superficial lymphadenopathy. Hematologically, they showed pictures resembling immune related thrombocytopenia and/or hemolytic anemia. Examination of the bone marrows revealed hypercellularity with increased number of megakaryocytes and erythroid cells and various degrees of abnormal lymphoid cell infiltration. The histopathologic section of the spleen from one patient who underwent splenectomy revealed abnormal cell infiltration in the sinusoids of the red pulp. Lymphoma cells showed T gamma/delta lymphoid immunophenotype (CD3+ CD2+ CD4- CD8-, TCR delta-1+, and beta F1-). The platelet counts were elevated transiently after initial treatment with corticosteroids, but the condition soon deteriorated. All died of refractory lymphoma five to nine months after diagnosis. Review of the literature, showed that only four other cases have been reported until now and although no cytogenetic data were available for these patients, they had very similar clinical pictures as those in this series. It is suggested that hepatosplenic T gamma/delta lymphoma represents a rare, but distinct, clinicopathological and cytogenetic entity.

Concentration of arsenic, selenium, zinc, iron and copper in the urine of blackfoot disease patients at different clinical stages

Atomic absorption spectrophotometric methods were developed for the determination of arsenic, selenium, iron, zinc, and copper in the urine samples. Data collected from blackfoot disease patients at five clinical stages were compared with those from healthy controls. Spectrophotometry was also used to compare the concentrations and detection levels of these elements in blood and hair samples. The copper concentration in urine changed slightly for all clinical stages, whereas the concentrations in blood and hair showed less correlation with the stages of blackfoot disease. The zinc concentration in urine increased with the clinical stage, the fourth stage having the highest concentration. The zinc concentrations in urine were not correlated with those of blood and hair samples. Zinc appears to be associated with the occurrence of scaling and cracking of the skin of the fingers or feet, and is even closely correlated with the degree of ulceration and gangrene of blackfoot disease patients. The more advanced degrees of blackfoot disease patients were associated with a greater zinc concentration in the urine. Arsenic, which is claimed to be a major causative agent of blackfoot disease, increased from the zero stage and showed a particularly high concentration in the second stage. The arsenic concentration in urine showed a positive correlation with that in the blood and the hair. Arsenic is indicated as major causative agent of blackfoot disease. The selenium concentration decreased from the zero stage, showing its lowest value during the second stage, then increased in the later stages. Changes in the selenium concentration in the urine were the inverse of those observed for the arsenic concentration in blood and hair. The decrease of selenium is attributed to the antagonistic effect of arsenic; selenium is retained during the initial stages. Iron increased from the zero stage to the second stage and showed the highest concentration of all the measured elements. It then decreased in the advanced stages of the disease. Iron may have an interactive effect with arsenic in the initial stages, resulting in loss of haemoglobin during the advanced stages. The antagonistic effect of selenium and the interactive effect of iron on arsenic warrant further study.

Platelet lysis and functional perturbation by 13-methyl myristate. The major fatty acid in Flavobacterium ranacida

Flavobacterium ranacida consisted of 75% of 13-methyl myristate in total fatty acids. The acid at > 60 microM caused the lysis of gel-filtered platelets (GFP) in both time- and concentration-dependent manners. Scanning electron microscopy showed that: 1). GFP in 40 microM of the acid changed the morphology to speculate discoid shape at 15 sec, and to ellipsoids after 30 sec; and 2), the cells gradually swelled to spherical forms as the concentration of the acid increased. At nonlytic concentration, the acid inhibited platelet responses to various agonists with differential concentrations. The order of inhibitory potency was U46619 > low dose collagen > ADP-fibrinogen > phorbol ester > high dose collagen. The results demonstrated that 13-methyl myristate exhibited both cell lytic activity and perturbation on membrane function.

Dopamine release in the nucleus accumbens during sexual behavior in prenatally stressed adult male rats

In vivo microdialysis experiments were performed on the nucleus accumbens (NAc) during observation of sexual behavior (including motivation and copulation) to determine if there were any changes in NAc dopamine (DA) transmission in prenatally stressed (PS) adult male rats. Approximate 37% of control males and 83% of PS males did not exhibit copulation during the sexual behavior tests and no significant changes in NAc DA release were seen during exposure to estrous females. In contrast, both control and PS males that displayed copulatory behavior showed a marked increase in NAc DA release when presented with a sexually receptive female behind a screen and this increased further during actual copulation. The increase in DA release in copulatory PS males was not significantly different from that in sexually active control males. In addition, a similar extent in DA release induced by high potassium perfusate was observed in all rats. These results suggest that prenatal stress may result in a deficit in DA neurotransmission in the NAc and this deficit may possibly cause impaired male sexual behavior in rats.

Effects of age on dopamine release in the nucleus accumbens and amphetamine-induced locomotor activity in rats

The effects of age on dopamine (DA) release in the nucleus accumbens (NAc) and on amphetamine (AMPH)-induced locomotor activity were studied by microdialysis in freely-moving young (5 month) and old (24 month) rats. Both basal extracellular DA and 3,4-dihydroxyphenylacetic acid (DOPAC) release and that following intra-accumbens perfusion of AMPH (1-10 microM) were significantly lower in old rats. After intraperitoneal injection of AMPH (1.5 mg/kg), no age-related change in DA release was seen in the NAc, but locomotor activity was found to increase much more in young rats than in old ones. These results indicate that (1) old rats show decreased extracellular DA and DOPAC release, both in the basal state and following intra-accumbens infusion of AMPH, and (2) the age-related locomotor activity induced by systemic injection of AMPH is not paralleled by changes in DA release in the NAc.

[Hyperdynamic status in a partial portal vein ligated (PVL) rat's portal hypertension model]

The splanchnic and systemic hemodynamics were measured by radioactive microsphere techniques in a PVL rat's model with portal hypertension. The portal-hypertensive rats (1.75 +/- 0.24 vs. 1.23 +/- 0.13 kPa, P < 0.001) with greater than 93% portal-systemic shunting had an increase in portal venous inflow by 50% (8.97 +/- 0.8 vs. 6.03 +/- 0.28 ml.min-1.100gBW-1; P < 0.001) and a concomitant decrease by 40% in splanchnic arteriolar resistance (0.27 +/- 0.05 vs. 0.42 +/- 0.05kPa.ml-1.min-1.100gBW-1; P < 0.01) compared with control rats. Cardiac index (54.6 +/- 4.4 vs. 36.5 +/- 3.0 ml.min-1.100gBW-1) was elevated by 50% (P < 0.001), and total peripheral resistance (0.052 +/- 0.006 vs. 0.084 +/- 0.009 kPa.ml-1.min-1.100gBW-1) was decreased by 40% (P < 0.001). The resistance to portal blood flow in portal vein-stenotic rats (0.087 +/- 0.011kPa.ml-1.min-1) was similar to that in control rats (0.076 +/- 0.01kPa.ml-1.min-1), indicating that the hyperdynamic portal venous inflow, not resistance, was the mainstay of the elevated portal venous pressure. Which is in favor of the forward flow theory of portal hypertension. The systemic hemodynamic parameters were secondary to the splanchnic hemodynamic changes.

Separation of Chinese Leishmania isolates into five genotypes by kinetoplast and chromosomal DNA heterogeneity

Leishmaniasis remains endemic in China, especially in the west and northwest frontier regions in central Asia. Epidemic outbreaks of both visceral and cutaneous forms of the disease have become a serious concern in view of such events occurring in neighboring countries. In the present study, we have begun to characterize available parasites as an initial step in understanding the epidemiology of leishmaniasis in central Asia. Nineteen Leishmania isolates collected since the 1950s from epidemiologically different foci in China were separated into five genotypes (Groups I-V) based on their polymorphisms in both kinetoplast (kDNA) and nuclear (nDNA) DNAs. Both kDNA and nDNA are conserved in Group I, which consists of six isolates, i.e., five cases of human kala-azar and one case of canine leishmaniasis isolated from three distant foci more than 30 years apart. In contrast, both kDNA and nDNA are heterogeneous in Group II, consisting of 10 isolates scattered in the plain area from the eastern coast to the western desert. This group includes five kala-azar cases, one post-kala-azar dermal leishmaniasis case, two sand fly isolates, and two canine isolates. The remaining three groups (III-V), two from great gerbils (Rhombomys opimus) and one from a kala-azar case, differ among themselves and from the aforementioned groups. Groups I, II/III, IV, and V contain isolates that have been recognized epidemiologically or typed isoenzymatically as L. donovani s.l., L. infantum s.l., L. turinica, and L. gerbilli, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Assembly of HIV GAG-B-galactosidase fusion proteins into virus particles

We have studied the assembly of human immunodeficiency virus (HIV-1) Gag-B-galactosidase (Gag-B-gal; GBG) fusion proteins into HIV particles in the presence of HIV Gag proteins. Release of fusion proteins from cells was measured by assay of media versus cellular B-gal activities and was dependent on co-expression of unfused Gag proteins. Gag-B-gal incorporation into virus particles was demonstrated by detergent treatment and density gradient fractionation studies and was dependent on protein-protein interactions requiring the C-terminal two-thirds of the HIV CA domain. The central MA domain appeared unimportant for fusion protein incorporation; a nonmyristylated GBG protein was incorporated but at a relatively reduced level, while the NC and p6 domains slightly affected the assembly of fusion proteins into particles. Subcellular fractionation studies showed that all fusion proteins including the nonmyristylated one were enriched in the cytoplasmic pellet fraction. However, assembly into particles did not correlate with subcellular fractionation patterns. Similarly, virion incorporation levels of Gag-B-gal proteins did not correlate with their immunofluorescence localization patterns. However, we observed that while most fusion proteins displayed a perinuclear ring with heterogeneous staining throughout cells, short fusion proteins appeared enriched on the intracellular membranes, and fusion proteins with intact MA but deleted NC domains showed an enhanced surface staining without a clear perinuclear ring. Altogether, our data suggest that the CA domain is the primary determinant for assembly of HIV fusion proteins into virus particles.

Activation of human platelet phospholipases C and A2 by various oxygenated triterpenes

Eight structural analogues of oxygenated triterpenes exerted striking differences in activation of human platelets. They are four pairs of stereoisomers and two pairs of positional isomers with varying: 1) acetoxyl/hydroxyl substituents; 2) the position of the substituents at C-3 and C-15; and 3) the stereochemistry of a substituent at C-3. It required a threshold concentration for each agent to cause the concentration-dependent activation. These triterpenes were hydrophobic with < 20% difference in the partition coefficients between 1-octanol and water. They caused differential effects on: inositol triphosphate production; the increase in [Ca2+]i; diacylglycerol formation; phosphatidic acid accumulation, protein phosphorylations and arachidonate release. These agents activated both phospholipases C and A2. The trend of activating phospholipase C was triterpenes with two acetoxyl substituents > one acetoxyl/one hydroxyl substituents > two hydroxyl substituents. In activating phospholipase A2, triterpenes with two acetoxyl substituents were most effective, whereas the paired isomers with a hydroxyl group at C-15 alpha and an acetoxyl substituent at C-3 failed the activation. The results enable one to discuss the possible structure-activity relationship of various oxygenated triterpenes in the activation of both phospholipases C and A2.

Studies on the concentrations of arsenic, selenium, copper, zinc and iron in the hair of blackfoot disease patients in different clinical stages

Flame atomic absorption spectrophotometric methods were developed for, arsenic, selenium, copper, zinc and iron in hair samples. Data from blackfoot disease patients at five clinical stages were compared with those from healthy controls. The copper and zinc concentrations showed only slight differences in all clinical stages, which indicated the less relation to blackfoot disease. The decrease of selenium and iron in all stages was attributed to the antagonistic effect of arsenic; arsenic increased in the first and second stages, but decreased in the later stages. The decrease of selenium and iron during the progression of the disease is thought to be due to persistence of the antagonistic effect of arsenic in the initial stages, so that very low concentrations of selenium are found in the advanced stages, despite the later decrease of arsenic. There was also a progressive decrease of iron with advance of the disease, and the later stages also showed a decrease in haemoglobin. It was shown that arsenic is a major cause of blackfoot disease, and that it antagonises selenium and iron, which decreased in the advanced clinical stages of the disease.

Conditional infectivity of a human immunodeficiency virus matrix domain deletion mutant

We constructed a human immunodeficiency virus (HIV) matrix (MA) deletion mutant by deletion of about 80% of the HIV type 1 Gag MA domain but retaining myristylation and proteolytic processing signals. The effects of this deletion matrix (dl.MA) mutant on HIV particle assembly, processing, and infectivity were analyzed. Surprisingly, the dl.MA mutant still could assemble and process virus particles, had a wild-type (wt) retrovirus particle density, and possessed wt reverse transcriptase activity. RNase protection experiments showed that dl.MA mutant particles preferentially packaged viral genomic RNA. When both mutant and wt particles were pseudotyped with an amphotropic murine leukemia virus envelope protein, mutant infectivity was about 10% of wt level. In contrast, infectivity of the dl.MA mutant was 1,000-fold less than that of wild-type when mutant and wt particles were pseudotyped with the HIV envelope protein. Protein analyses of pseudotyped virions indicated that there were no major differences between mutant and wt viruses in the efficiency of amphotropic murine leukemia virus envelope protein incorporation. In contrast, there was a reduction in the amount of mutant particle-associated HIV envelope protein gp120. Our results suggest that an intact HIV matrix domain is not absolutely required for reverse transcription, nuclear localization, or integration but is necessary for appropriate HIV envelope protein function.

Studies on the concentration of arsenic, selenium, copper, zinc and iron in the blood of blackfoot disease patients in different clinical stages

Flame atomic absorption spectrophotometric methods were developed for the determination of zinc, copper, arsenic, iron and selenium in blood samples. Data from blackfoot disease patients in five clinical stages were compared with those from healthy controls. Copper concentrations were the same for all clinical stages. Arsenic increased in the initial three stages but decreased thereafter, although arsenic was previously considered to be the major causative agent of the disease. The decrease of arsenic in the later stages was attributed to the antagonistic effect of selenium, and the decrease of iron during the progress of the disease is thought to be due to the antagonistic effect of arsenic in the initial stages and the loose of haemoglobin in the later stages.

Treatment of filarial lymphoedema and elephantiasis with 5,6-benzo-alpha-pyrone (coumarin)

OBJECTIVE

To study efficacy of treatment of filarial lymphoedema and elephantiasis with 5,6-benzo-alpha-pyrone.

DESIGN

Randomised, double blind, placebo controlled study with matching for grade and duration of disease, age, and sex. Treatment was given for 367 days, and subjects were followed up for another year.

SETTING

A town in Shandong Province, China.

SUBJECTS

104 men and women with chronic unilateral filarial lymphoedema or elephantiasis of the leg: 64 were randomised to benzopyrone and 40 to placebo. By the end of the study 19 patients had dropped out of the treatment group and two out of the placebo group.

INTERVENTIONS

Two 200 mg tablets of 5,6-benzo-alpha-pyrone or two placebo tablets given daily.

MAIN OUTCOME MEASURES

Volumes of the affected and normal legs estimated every three months, and daily listing of any side effects.

RESULTS

Benzopyrone reduced oedema for all grades of lymphoedema during the year of treatment (pW0.001) and the follow up year (p = 0.026). During treatment the mean monthly reductions in leg volume were 0.62% (95% confidence intervals 0.4% to 0.85%), 1.1% (0.71% to 1.6%), and 1.6% (0.89% to 2.3%) of the volume of the normal leg for grades 1, 2, and 3-5 (elephantiasis) of lymphoedema respectively. During follow up the mean monthly reductions were 0.18% (0.01% to 0.35%), 0.54% (0.27% to 0.82%), and 0.87% (0.51% to 1.2%). At the end of the trial the total reduction in oedema was 100%, 95%, and 45% for grades 1, 2, and 3-5. Symptoms and complications were considerably reduced, including attacks of secondary acute inflammation, while side effects were minor and disappeared after one month. In the placebo group there were no changes in the severity of lymphoedema.

CONCLUSIONS

5,6-benzo-alpha-pyrone reduces the oedema and many symptoms of filarial lymphoedema and elephantiasis. It has few side effects, and its relatively slow action makes it ideal for use without compression garments.

Assembly, processing, and infectivity of human immunodeficiency virus type 1 gag mutants

We studied the effects of gag mutations on human immunodeficiency virus type 1 (HIV-1) assembly, processing, and infectivity by using a replication-defective HIV expression system. HIV mutants were screened for infectivity by transduction of a selectable marker and were examined for assembly by monitoring particle release from transfected cells. Gag protein processing and reverse transcriptase activities of mutant particles were also assayed. Surprisingly, most Gag protein mutants were assembled and processed. The two exceptions to this rule were a myristylation-minus mutant, and one gag matrix domain mutant which expressed proteins that were trapped intracellularly. Interestingly, a mutant with a 56-amino-acid deletion within the HIV gag capsid domain still could assemble and process virus particles, exhibited a wild-type retrovirus particle density, and had wild-type reverse transcriptase activity. Indeed, although most HIV-1 gag mutants were noninfectious or poorly infectious, they produced apparently normal particles which possessed significant reverse transcriptase activities. These results strongly support the notion that the HIV-1 Gag proteins are functionally involved in post-assembly, postprocessing stages of virus infectivity.

The mode of action of primary bile salts on human platelets

Cholate and its conjugated amide derivatives glycocholate and taurocholate solubilized human platelets differently as studied by the observations on: (1) the change in optical absorbance of platelet suspension, (2) marker leakiness and (3) component solubility. Cholate ruptures the membrane in an all-or-none process, while both conjugated derivatives shed off both proteins and lipids. The shed lipids formed vesicles and could be separated from the proteins. The conjugated salts gradually chop off the cell membrane into pieces causing the cells to become small spheres (1.5 microns in diameter) as revealed by scanning electron microscopy, which also revealed that morphological change of platelet in these bile salts depended on both concentration and incubation period. Platelets at the prelytic-stage concentration of these three salts deformed initially to spiculate disc and finally to a stretched-out flat form. Also, in the prelytic stage of these bile salts, platelets showed inhibited responses to thrombin which did not happen to platelets in deoxycholate (Shiao et al. (1989) Biochim. Biophys. Acta 980, 56-68.).

Activation of human platelets by the rabbit anticardiolipin antibodies

Affinity purified anticardiolipin antibodies (ACLA) raised in rabbits showed cross-reactivities with various negatively charged phospholipids as shown by both the solid phase enzyme-linked immunosorbent assay (ELISA) and inhibition studies. In ELISA, ACLA showed strong cross-reactivity to both sphingomyelin (SM) and phosphatidylethanolamine (PE), but the inhibition studies showed that ACLA failed to bind the aqueous suspensions of SM, PE, and PE/PC (1:1). ACLA bound to resting gel-filtered human platelets (GFP) as shown by both inhibition study and flow cytofluorometric analysis. Western blotting procedure showed that ACLA strongly cross-reacted to an 80-Kd plasma membrane protein. ACLA activated platelet response in a concentration-dependent manner. At less than 10 micrograms/mL, ACLA induced both platelet shape change to spiculate irregular forms as shown by scanning electron microscopy and the phosphorylation of 20-Kd protein. ACLA at more than 10 micrograms/mL caused platelet aggregation and secretion. The aggregation was inhibited by EDTA; aspirin; antimycin A plus 2-deoxyglucose; PGE1; and the F(ab')2 fragment of ACLA. It was not inhibited by monoclonal antibody to Fc receptor (MoAb FcR2). The biochemical events of ACLA-induced platelet response involved the elevation of (1) thromboxane A2 formation, (2) cytosolic free calcium ion concentration ([Ca2+]i), and (3) 47-Kd protein phosphorylation. In addition, the subaggregatory concentration of ACLA showed synergistic platelet activation with that concentration of thrombin, collagen, and epinephrine. The study showed the mechanism involved in ACLA-induced platelet responses.