Plasmodium berghei: quantitation of in vitro effects of antimalarial drugs on exoerythrocytic development by a ribosomal RNA probe

A stage-specific ribosomal RNA probe has been used to quantitate exoerythrocytic development of Plasmodium berghei in primary cultures of mouse hepatocytes. Parasite rRNA could be detected as soon as 6 hr after sporozoite invasion and was increased during schizogony to a maximum at 48 hr, when mature schizonts were identified by microscopy. As few as 10 exoerythrocytic schizonts could be detected by filter blot hybridization, followed by autoradiography and liquid scintillation counting. By hybridizing the culture rRNA samples with either parasite-specific or universal rRNA probes, the in vitro tissue schizonticidal activity and hepatotoxicity of primaquine, two of its analogues, and pyrimethamine, could be assessed. After a 48-hr exposure of the culture to serial dilutions of each drug, a quantitative relationship was demonstrated between the decrease of the parasite rRNA and the increase of the drug concentrations. No significant parasite-specific rRNA could be detected at the concentration achieving complete inhibition of schizont formation but causing no cytotoxic effects on host hepatocytes. In contrast to microscopic-based assays, this molecular approach provides an objective and quantitative in vitro method for rapid screening and evaluation of tissue schizonticidal antimalarials.

Evaluation of the mechanical properties of hot isostatically pressed titania and titania-calcium phosphate composites

A number of composites based on titania and calcium phosphates, hydroxyapatite, bone ash or beta-tricalcium phosphate, were sintered by glass-encapsulated hot isostatic pressing at 925 degrees C. The mechanical properties of the titania and titania-calcium phosphate composites--three-point bending strength, fracture toughness and Young's modulus--were 250-450 MPa, 2.5-2.9 MPa m1/2 and 230-270 GPa, respectively. Hardness and density were also measured. The results suggest that these composites have potential applications in medicine as implant materials.

In vitro replication competence of a cloned hepatitis B virus variant with a nonsense mutation in the distal pre-C region

Hepatitis B virus (HBV) variants with a nonsense mutation in the distal pre-C region have been detected in patients positive for anti-HBe, and the complete nucleotide sequence of one cloned pre-C variant has been determined. Transfection of this HBV variant clone into the human hepatoma cell line HepG2 resulted in the appearance of major HBV transcripts, replicative forms of viral DNA evidenced by both molecular hybridization and endogenous DNA polymerase assay, as well as the expression and secretion of HBsAg and HBcAg particles. Western blotting revealed only the 21-kDa HBcAg but not the 17-kDa HBeAg. These results demonstrate the replication capacity of the HBV variant with a nonfunctional pre-C region despite its inability to express HBeAg.

Amelioration of light-induced retinal degeneration by a calcium overload blocker. Flunarizine

Although free radical formation and lipid peroxidation have been implicated in photoreceptor degeneration following continuous light exposure, recent evidence led us to hypothesize that excessive stimulation of the photoreceptor cells in prolonged light exposure may cause intracellular calcium overload and consequent photoreceptor cell injury. To test this hypothesis, we studied the effects of flunarizine hydrochloride, a calcium overload blocker that inhibits the inositol 1,4,5-triphosphate-induced release of intracellular stores of calcium, in an established rat model of light-induced retinal degeneration. Light and electron microscopic examination of the flunarizine-treated retinas revealed remarkable preservation of the retinal pigment epithelium, rod inner and outer segments, nuclei, and synapses of the photoreceptor cells at all phases of the recovery period. This observation was further supported by morphometric evaluation of the outer nuclear layer thickness, which revealed a greater preservation of the photoreceptor nuclei in the drug-treated animals at 6 and 14 days after exposure. In addition, the rhodopsin levels in the flunarizine-treated retinas were also significantly higher than in the controls in all phases of recovery. The ability of flunarizine to ameliorate light-induced retinal degeneration in the rat supports our hypothesis that elevated intracellular calcium may indeed play a role in light-induced photoreceptor degeneration.

[Identification of tinglizi by derivative spectrum]

This paper reports a study on the application of derivative spectrum to the identification of tinglizi and its adulterants. The spectra of two normal species of tinglizi have been found identical, but those of six adulterants obviously different from the normal.

Association of proteases of Porphyromonas (Bacteroides) gingivalis with its adhesion to Actinomyces viscosus

P. gingivalis adheres to A. viscosus on mineral surfaces mimicking teeth. To study whether P. gingivalis proteases contribute to its binding, mutants of P. gingivalis deficient in proteases were compared with their parent strain and a P. gingivalis-type strain for their adherence to A. viscosus on saliva-coated hydroxyapatite by manipulating a radio-isotope binding assay. Adherence of P. gingivalis 2561 to A. viscosus was studied by tests of the effects of incubation temperature and known inhibitors or promoters of proteases. Controls were handled by the assay run in PBS buffer at 22 degrees C. Two mutants deficient in trypsin-like protease were found to be deficient in adherence (% attachment relative to control: 3.2 +/- 0.1% and 11.2 +/- 0.4%), while a collagenase-deficient mutant had an adherence score (51.6 +/- 8.4) closer to that of the parent strain (75.6 +/- 7.2%). Heating P. gingivalis at 70 degrees C decreased its subsequent adherence at 22 degrees C by 80%. Adherence decreased by 60% when the assay was run at 4 degrees C, but increased by 70% at 37 degrees C. Reducing agents (dithiothreitol, cysteine, and mercaptoethanol) enhanced P. gingivalis adherence by 50 to 60%. Protease inhibitors (BZMD, SBTI, TPCK, TLCK, CMPS, PMSF) decreased adherence by 10 to 50%. Also, Hg2+ and Zn2+ decreased adherence by 30 to 50%, and arginine decreased it by 50%. Most of these effects on P. gingivalis adherence were statistically significant (p less than 0.05). Analysis of these data suggests that P. gingivalis proteases may contribute to the cohesion of P. gingivalis and A. viscosus.

Mitochondrial metabolism of valproic acid

The beta-oxidation of valproic acid (2-propylpentanoic acid), an anticonvulsant drug with hepatotoxic side effects, was studied with subcellular fractions of rat liver and with purified enzymes of beta-oxidation. 2-Propyl-2-pentenoyl-CoA, a presumed intermediate in the beta-oxidation of valproic acid, was chemically synthesized and used to demonstrate that enoyl-CoA hydratase or crotonase catalyzes its hydration to 3-hydroxy-2-propylpentanoyl-CoA. The latter compound was not acted upon by soluble L-3-hydroxyacyl-CoA dehydrogenases from mitochondria or peroxisomes but was dehydrogenated by an NAD(+)-dependent dehydrogenase associated with a mitochondrial membrane fraction. The product of the dehydrogenation, presumably 3-keto-2-propylpentanoyl-CoA, was further characterized by fast bombardment mass spectrometry. 3-Keto-2-propylpentanoyl-CoA was not cleaved thiolytically by 3-ketoacyl-CoA thiolase or a mitochondrial extract but was slowly degraded, most likely by hydrolysis. The availability of 2-propylpentanoyl-CoA (valproyl-CoA) and its beta-oxidation metabolites facilitated a study of valproate metabolism in coupled rat liver mitochondria. Mitochondrial metabolites identified by high-performance liquid chromatography were 2-propylpentanoyl-CoA, 3-keto-2-propylpentanoyl-CoA, 2-propyl-2-pentenoyl- CoA, and trace amounts of 3-hydroxy-2-propylpentanoyl-CoA. It is concluded that valproic acid enters mitochondria where it is converted to 2-propylpentanoyl-CoA, dehydrogenated to 2-propyl-2-pentenoyl-CoA by 2-methyl-branched chain acyl-CoA dehydrogenase, and hydrated by enoyl-CoA hydratase to 3-hydroxy-2-propylpentanoyl-CoA.(ABSTRACT TRUNCATED AT 250 WORDS)

Hysteroscopic hydrotubation for treatment of tubal blockage

In order to increase the effectiveness of hydrotubation, a plastic cannula was inserted into the fallopian tube under hysteroscopic control. Fifty women with tubal blockage confirmed by HSG were selected for treatment. Hydrotubation solution consisted of hydrocortisone (20 mg), gentamicin (160,000 IU) and procaine (80 mg) in 20 ml distilled water. Repeat HSG was performed. After three treatments, tubal patency (one or both tubes) was achieved in 20 women (40%), and seven pregnancies resulted within 1-18 months. Hysteroscopic hydrotubation may be an alternative treatment for tubal blockage.

Activation of the double-stranded RNA-dependent eIF-2 alpha kinase by cellular RNA from 3T3-F442A cells

The interferon induced double-stranded-RNA-dependent eIF-2 alpha kinase has an established role in mediating part of interferons anti-viral effects. Several studies have suggested that it may have additional functions in cells not infected with virus. The mechanism of activation of the kinase and the consequences of its activity in uninfected cells remain to be determined. Our previous results have indicated that the activation (phosphorylation) of this kinase may be an important regulatory signal to the arrest of growth of mouse 3T3-F442A fibroblasts and their subsequent differentiation to adipocytes. We have found that the phosphorylation of the kinase occurred in vivo in the absence of viral infection and in vitro without the addition of dsRNA. We demonstrate here that total cytoplasmic RNA from 3T3-F442A cells contains a regulatory RNA(s) capable of activating dsRNA-dependent eIF-2 alpha kinase. Fractionation of the cytoplasmic RNA by oligo(dT)-cellulose indicated that the regulatory RNA eluted with the poly(A)-rich RNA fraction. It bound tightly to the dsRNA-dependent eIF-2 alpha kinase and was immune-precipitated with its antibodies as a complex of regulatory RNA and dsRNA-dependent eIF-2 alpha kinase. The regulatory RNA activity was further purified by phenol extraction of immune precipitates containing this complex. These findings indicated that the regulatory RNA forms a specific complex with the dsRNA-dependent eIF-2 alpha kinase. The activity of the regulatory RNA was sensitive to the dsRNA-specific RNase VI but not to proteinase K, DNase I or ssRNA-specific RNase T1. The activation of the dsRNA-dependent eIF-2 alpha kinase by regulatory RNA was prevented by addition of a high concentration of poly(I).poly(C). The regulatory RNA was also shown to activate partially purified dsRNA-dependent eIF-2 alpha kinase prepared from rabbit reticulocyte lysates and to inhibit protein synthesis in reticulocyte lysates. Our findings, that cellular RNAs can specifically activate the dsRNA-dependent eIF-2 alpha kinase, are consistent with a physiological role for the dsRNA-dependent eIF-2 alpha kinase and interferon during cell growth and differentiation. The relationship of the regulatory RNA activity to growth and differentiation of 3T3-F442A cells is discussed.

Synthesis, purification and stability of no carrier added radioiodinated 1,1-bis(4-hydroxyphenyl)-2-iodo-2-phenylethylene (IBHPE), a prototype triphenylethylene estrogen-receptor binding radiopharmaceutical

A triphenylethylene compound [1,1-bis(4-hydroxyphenyl)-2-iodo-2-phenylethylene; IBHPE] has been labeled by halodestannylation with 123I at a specific radioactivity of 13,200 Ci/mmol (by in vitro receptor assay) after HPLC purification. The corresponding 80mBr-labeled compound (BrBHPE), which has a 3-fold higher affinity for the estrogen receptor, was previously prepared and examined as a potential therapeutic radiopharmaceutical exploiting Auger electron toxicity. Stability of IBHPE was a concern because free iodide was generated when HPLC solvents were removed with a stream of nitrogen in a glass vial; however, decomposition was minimal when polypropylene vials were used, and ethanol solutions of [123I]IBHPE were stable for several days at 0-4 degrees C. Tissue distribution studies of IBHPE after intraperitoneal injection to mature female rats showed highest estradiol-inhibitable uptake in the peritoneal estrogen-receptor rich tissues (uterus, ovaries and vagina) at 30 min. Specific uptake (percent dose per gram) in the pituitary, and peritoneal target tissue-to-blood ratios were greater at 2 h than 30 min. In immature female rats, uterus-to-blood ratios of greater than 50, progressively lowered by increasing diethylstilbestrol levels, were obtained. These data demonstrate good binding of IBHPE to the estrogen receptor in vivo, in spite of extensive non specific binding in in vitro estrogen receptor assays. Most of the label in the uterus at 1 h after injection was still unchanged IBHPE. Our results suggest that IBHPE or related 123I-labeled iodovinyl triphenylethylenes could have diagnostic or therapeutic radiopharmaceutical utility.

[Experimental studies on the absorption of aconitine in the upper digestive tract]

This paper presents the experimental results of the absorption of orally administered aconitine in the upper digestive tract of rats. Taking the atrioventricular block in EKG as the main parameter, we have found that aconitine could be absorbed by the esophagus and stomach of the rat. Furthermore, the ability of the esophagus to absorb aconitine is stronger than that of the stomach.

[Activity of serum angiotensin converting enzyme in pregnancy-induced hypertension]

Activity of serum angiotensin converting enzyme (SACE) was measured in serum of 33 pregnant women with normal blood pressure or pregnancy induced hypertension (PIH), using sensitive Hippurate colorimetric micromethod. The mean level of SACE activity in 17 PIH patients (73.25 +/- 18.81 U/ml) was significantly higher than that in normotensive pregnant women (16 cases) ( 52.36 +/- 9.91 U/ml) (P less than 0.01). The mean arterial blood pressure showed a positive correlation with the level of SACE activity in all pregnant women (Y = 69.089 + 0.494x, r = 0.562, P less than 0.01). In PIH patients, the gestosis index and degree of edema also had statistically significant correlation with the level of SACE activity (Y = -0.560 + 0.056x, r = 0.549, P less than 0.01) (Y = -1.760 + 0.043x, r = 0.629, P less than 0.05). The amount of 24h urinary protein was independent of the level of SACE activity. It suggests that disturbance in regulation of ACE activity may be one of the factors responsible for the development of PIH.

Crystal structure of the RNA-binding domain of the U1 small nuclear ribonucleoprotein A

The crystal structure of the RNA binding domain of the U1 small nuclear ribonucleoprotein A, which forms part of the ribonucleoprotein complex involved in the excision of introns, has been solved. It contains a four-stranded beta sheet and two alpha helices. The highly conserved segments designated RNP1 and RNP2 lie side by side on the middle two beta strands. U1 RNA binding studies of mutant proteins suggest that the RNA binds to the four-stranded beta sheet and to the flexible loops on one end.

Identification of individual human immunodeficiency virus type 1 gp120 amino acids important for CD4 receptor binding

The binding of the CD4 receptor by the human immunodeficiency virus type 1 gp120 exterior envelope glycoprotein is important for virus entry and cytopathic effect. To investigate the CD4-binding region of the gp120 glycoprotein, we altered gp120 amino acids, excluding cysteines, that are conserved among the primate immunodeficiency viruses utilizing the CD4 receptor. Changes in two hydrophobic regions (Thr-257 in conserved region 2 and Trp-427 in conserved region 4) and two hydrophilic regions (Asp-368 and Glu-370 in conserved region 3 and Asp-457 in conserved region 4) resulted in significant reductions in CD4 binding. For most of the mutations affecting these residues, the observed effects on CD4 binding did not apparently result from global conformational disruption of the gp120 molecule, as assessed by measurements of precursor processing, subunit association, and monoclonal antibody recognition. The two hydrophilic regions exhibit a strong propensity for beta-turn formation, are predicted to act as efficient B-cell epitopes, and are located adjacent to hypervariable, glycosylated regions. This study defines a small number of gp120 residues important for CD4 binding, some of which might constitute attractive targets for immunologic intervention.

[Computed tomography and magnetic resonance imaging of choroidal melanoma]

Ten choroidal melanomas studied were with computed tomography (CT, nine cases) and magnetic resonance imaging (MRI, one case). Both techniques detected all the intraocular tumors with localization and determination of the extent of the lesions. Three of them were found to have extraocular extension. Because both T1 and T2 were relatively shortened in melanoma, on T-weighted MR image, the tumor was seen as an area of moderately high signal and on T weighted image, melanoma appeared as an area of low signal. MRI can provide a histological diagnosis of this tumor.

Effect of radix Salviae miltiorrhizae extract injection on survival of allogeneic heart transplantation

The effect of Radix Salviae Miltiorrhizae (RSM), a commonly used herbal blood circulation invigorator for the treatment of blood stasis in traditional Chinese medicine, on the duration of allograft survival following heterotopic heart transplantation in experimental animals was observed. The results in three heart transplantation models--auricular free graft in mice, abdominal graft in rats and cervical graft in rabbits--suggested that RSM injection in an appropriate dosage prolonged the survival time of cardiac allograft. The herb showed no significant toxicity. It was also found that RSM injection had a synergic effect with corticosteroids against graft rejection.

A seral epidemiological study of HIV transmitted through human seral gamma-globulin preparations

In order to study the potential risk of transferring HIV through human seral gamma-globulin preparations (immunoglobulin), indirect immunofluorescent antibody test (IFA) and Western Blot (WB) assay were applied to 343 random samples (sera) with previous injection of imported human seral gamma-globulins (Ig) positive for Human Immunodeficiency Virus (HIV) antibodies between 1981-1987 for the detection of HIV antibodies. All results were negative and tests on all 23 controls who had previously received Ig made in China also gave negative results. However all 12 batches of imported Ig collected from the above-mentioned users, were positive for HIV antibodies when tested by WB and IFA. This study shows that under normal conditions, human seral gamma-globulin does not transmit HIV.

Subtypes of alpha 1-adrenoceptors in rat blood vessels

Two alpha 1-adrenoceptor subtypes (alpha 1A and alpha 1B) have been distinguished by competitive antagonists and the alkylating agent chloroethylclonidine. The chloroethylclonidine-insensitive subtype (alpha 1A) has been suggested to selectively activate Ca2+ influx through dihydropyridine-sensitive channels in smooth muscle. We compared the effects of chloroethylclonidine and nifedipine on contractile responses to norepinephrine (NE) in rat blood vessels. Pretreatment with chloroethylclonidine caused a large shift to the right and decrease in maximum for NE-induced contractions of rat aorta, however, nifedipine had no effect in this tissue. Chloroethylclonidine had no effect on NE-induced contractions of rat renal arteries, which were almost completely abolished by nifedipine. Both chloroethylclonidine and nifedipine partially attenuated NE-induced contractions in rat mesenteric artery and portal vein. Addition of nifedipine abolished residual contractions remaining after chloroethylclonidine pretreatment in all four types of vessels. The pA2 for the competitive antagonist WB 4101 was highest in renal artery and lowest in aorta. These results suggest that the sensitivity of rat blood vessels to chloroethylclonidine is inversely related to their sensitivity to nifedipine, and support the existence of two alpha 1-adrenoceptor subtypes in rat blood vessels. Rat aorta appears to contain primarily alpha 1B receptors, renal artery primarily alpha 1A, and mesenteric artery and portal vein mixtures alpha 1A of and alpha 1B.

Geographic association of Helicobacter pylori antibody prevalence and gastric cancer mortality in rural China

To examine the geographic association between Helicobacter pylori infection and gastric cancer, we have assessed the prevalence of IgG antibodies to H. pylori in plasma samples taken in 1983 from 1882 men, aged 35-64 years, in 46 rural counties of the People's Republic of China. The gastric cancer mortality rates in these countries in 1973-75 varied from 3 per 1,000 (cumulative rate, 0-64 years) to 69 per 1,000, while the proportions of the population positive for H. pylori antibodies (based on an average of about 41 men per county) varied from 28% to 96%. After correction for the limited number of blood samples per county, the estimated correlation between H. pylori antibody prevalence and gastric cancer mortality was 40% (p = 0.02). No other type of cancer showed a significant association with H. pylori.

[A study on the dental adhesive containing phosphate diesters]

Although a lot of kinds of dental adhesives have been applied recently, all of them cannot meet clinical requirement completely. This paper reports a new dental adhesive containing partial phosphate diesters developed by us. We synthesized aryl phosphorodichloridates (APDC), nine kinds of phosphate diester (PDE) adhesive monomers, sodium p-toluenesulfinate (TSS) and p-toluenesulfinic acid (TSA) accelerators, polymethyl methacrylate (PMMA) powder and the other compounds. The chemical structures of PDE adhesive monomers were confirmed by IR, 1HNMR, 31PNMR, refractive index and elementary analysis etc. The results showed that the tensile bond strength (TBS) between PDE dental adhesive and human tooth was better than others reported in China and some others reported in literature.