Dengue overview: An updated systemic review

Dengue is caused by the dengue virus (DENVs) infection and clinical manifestations include dengue fever (DF), dengue hemorrhagic fever (DHF), or dengue shock syndrome (DSS). Due to a lack of antiviral drugs and effective vaccines, several therapeutic and control strategies have been proposed. A systemic literature review was conducted according to PRISMA guidelines to select proper references to give an overview of DENV infection. Results indicate that understanding the virus characteristics and epidemiology are essential to gain the basic and clinical knowledge as well as dengue disseminated pattern and status. Different factors and mechanisms are thought to be involved in the presentation of DHF and DSS, including antibody-dependent enhancement, immune dysregulation, viral virulence, host genetic susceptibility, and preexisting dengue antibodies. This study suggests that dissecting pathogenesis and risk factors as well as developing different types of therapeutic and control strategies against DENV infection are urgently needed.

Understanding the role of galectins toward influenza A virus infection

INTRODUCTION

Influenza A virus (IAV) is highly contagious and causes respiratory diseases in birds, mammals, and humans. Some strains of IAV, whether from human or avian sources, have developed resistance to existing antiviral drugs. Therefore, the discovery of new influenza antiviral drugs and therapeutic approaches is crucial. Recent studies have shown that galectins (Gal), a group of β-galactose-binding lectins, play a role in regulating various viral infections, including IAVs.

AREAS COVERED

This review provides an overview of the roles of different galectins in IAV infection. We discuss the characteristics of galectins, their impact on IAV infection and spread, and highlight their positive or negative regulatory functions and potential mechanisms during IAV infection. Furthermore, we explore the potential application of galectins in IAV therapy.

EXPERT OPINION

Galectins were first identified in the mid-1970s, and currently, 15 mammalian galectins have been identified. While all galectin members possess the carbohydrate recognition domain (CRD) that interacts with β-galactoside, their regulatory functions vary in different DNA or RNA virus infections. Certain galectin members have been found to regulate IAV infection through diverse mechanisms. Therefore, a comprehensive understanding of their roles in IAV infection is essential, as it may pave the way for novel therapeutic strategies.

Underlying mechanism of regulatory actions of diclofenac, a nonsteroidal anti-inflammatory agent, on neuronal potassium channels and firing: an experimental and theoretical study

Diclofenac (DIC), a nonsteroidal anti-inflammatory drug, is known to exert anti-nociceptive and anti-convulsant actions; however, its effects on ion currents, in neurons remain debatable. We aimed to investigate (1) potential effects of diclofenac on membrane potential and potassium currents in differentiated NSC-34 neuronal cells and dorsal root ganglion (DRG) neurons with whole-cell patch-clamp technology, and (2) firing of action potentials (APs), using a simulation model from hippocampal CA1 pyramidal neurons based on diclofenac's effects on potassium currents. In the NSC-34 cells, diclofenac exerted an inhibitory effect on delayed-rectifier K⁺ current (I(KDR)) with an IC₅₀ value of 73 μM. Diclofenac not merely inhibited the I(KDR) amplitude in response to membrane depolarization, but also accelerated the process of current inactivation. The inhibition by diclofenac of IK(DR) was not reversed by subsequent application of either naloxone. Importantly, diclofenac (300 μM) increased the amplitude of M-type K⁺ current (I)(KM)), while flupirtine (10 μM) or meclofenamic acid (10 μM) enhanced it effectively. Consistently, diclofenac (100 μM) increased the amplitude of I(KM) and diminished the I(KDR) amplitude, with a shortening of inactivation time constant in DRG neurons. Furthermore, by using the simulation modeling, we demonstrated the potential electrophysiological mechanisms underlying changes in AP firing caused by diclofenac. During the exposure to diclofenac, the actions on both I(KM) and I(KDR) could be potential mechanism through which it influences the excitability of fast-spiking neurons. Caution needs to be made in attributing the effects of diclofenac primarily to those produced by the activation of I(KM).

Human antibody and antigen response to IncA antibody of Chlamydia trachomatis

The high prevalence of C. trachomatis worldwide has underscored the importance of identifying specific immunogenic antigens in facilitating diagnosis as well as vaccine development. The aim of this study is to evaluate IncA antibody and antigen production in natural human infections. Our temporal expression study showed that IncA transcription and protein expression could be detected as early as 4 hours after the start of infection. Antibody responses could be detected in urine and genital swab samples from C. trachomatis-positive patients. It is especially interesting to note that the IncA antigen could be detected in urine. In conclusion, we have identified IncA as an important antigen in human. The potential applicability of the IncA antibody or antigen in the diagnosis as well as to vaccine development for C. trachomatis is also discussed.

15-Deoxy-Δ12,14-prostaglandin J2 suppresses IL-6-induced STAT3 phosphorylation via electrophilic reactivity in endothelial cells

In this study, the effects of 15d-PGJ(2) were investigated in IL-6-activated endothelial cells (ECs). 15d-PGJ(2) was found to abrogate phosphorylation on tyr705 of STAT3 in IL-6-treated ECs, in a dose- and time-dependent manner, but did not inhibit serine phosphorylation of STAT3 and the upperstream JAK2 phosphorylation. Other PPAR activators, such as WY1643 or ciglitazone, had no effect upon IL-6-induced STAT3 phosphorylation. Additionally, neither orthovanadate nor l-NAME treatment reverses the inhibition of STAT3 phosphorylation by 15d-PGJ(2). Otherwise, the effect of 15d-PGJ(2) requires the alpha,beta-unsaturated carbonyl group in the cyclopentane ring. A 15d-PGJ(2) analog, 9,10-Dihydro-15d-PGJ(2), which lack alpha,beta-unsaturated carbonyl group showed no increase in ROS production and no effect in inhibition of IL-6-induced STAT3 phosphorylation. The electrophilic compound, acrolein, mimics the inhibition effect of 15d-PGJ(2). Among the antioxidants, only NAC and glutathione reversed the effects of 15d-PGJ(2). NAC, glutathione and DTT all reversed the inhibition of STAT3 phosphorylation when preincubated with 15d-PGJ(2). The inhibition of ICAM-1 gene expression by 15d-PGJ(2) was abrogated by NAC and glutathione in IL-6-treated ECs. Taken together, these results suggest that 15d-PGJ(2) inhibits IL-6-stimulated phosphorylation on tyr705 of STAT3 dependent on its own electrophilic reactivity in ECs.

Upregulation of heme oxygenase-1 by Epigallocatechin-3-gallate via the phosphatidylinositol 3-kinase/Akt and ERK pathways

Heme oxygenase-1 (HO-1) is a cytoprotective enzyme activated by various phytochemicals and we examined the ability of Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, to upregulate HO-1 expression in endothelial cells (ECs). We demonstrate that EGCG induces HO-1 expression in a concentration- and time-dependent manner. Furthermore, EGCG-mediated HO-1 induction was abrogated in the presence of actinomycin D and cycloheximide, indicating that this upregulation of HO-1 occurred at the transcriptional level. EGCG also upregulates Nrf2 levels in nuclear extracts and increases ARE-luciferase activity. Furthermore, EGCG is the most potent inducer of HO-1 expression of the different green tea constituents that we analyzed, but had no detectable cytotoxic effects over the 25-100 microM dosage range. The inhibition of intracellular ROS production by N-acetylcysteine (NAC), glutathione (GSH), superoxide dismutase (SOD), catalase and the mitochondrial complex I inhibitor, rotenone, results in a decrease in EGCG-dependent HO-1 expression. In addition, we determined that tyrosine kinase is involved in EGCG induction of HO-1 as this is abrogated by genistein. ECs treated with EGCG exhibit activation of Akt and ERK1/2. In addition, pharmacological inhibitors of phosphatidylinositol 3-kinase and MEK1/2, which are upstream of Akt and ERK1/2, respectively, attenuate EGCG-induced HO-1 expression. On the other hand, pretreatment of these cells with EGCG exerts significant cytoprotective effects against H2O2, suggesting that the induction of HO-1 is an important component in the protection against oxidative stress. Hence, EGCG is a novel phytochemical inducer of HO-1 expression and we further identify the principal underlying mechanisms involved in this process.

Resveratrol suppresses IL-6-induced ICAM-1 gene expression in endothelial cells: effects on the inhibition of STAT3 phosphorylation

Resveratrol, a polyphenolic phytoaxelin present in red wine, has been suggested to protect against atherosclerosis and cardiovascular disease because of its antioxidant effects. Intercellular adhesion molecule (ICAM-1), induced by cytokines, has been hypothesized to play a role in the early events during atherosclerosis. In this study we tested the effects of resveratrol upon both IL-6-induced ICAM-1 gene expression and its underlying signaling pathways in endothelial cells (ECs). Resveratrol was found to inhibit both TNFalpha- and IL-6-induced ICAM-1 gene expression at the promoter, transcriptional and protein levels. Resveratrol also abrogates the tyr705 phosphorylation of STAT3 in IL-6-treated ECs, in a dose- and time-dependent manner. Although quercetin had similar effects, resveratrol showed higher inhibitory properties following 2-4 h pretreatments. Resveratrol has been shown to induce the activity of endothelial nitric oxide synthase (eNOS) and increase NO production. Consistent with this, the treatment of ECs with a NO donor (SNAP) reduces IL-6-induced STAT3 phosphorylation. Conversely, exposure of ECs to a NOS inhibitor reversed the effects of resveratrol upon IL-6-induced STAT3 phosphorylation. Furthermore, ECs transfected with constitutively active Rac1 (RacV12) showed increases in ICAM-1 promoter activity, intracellular reactive oxygen species (ROS) levels and STAT3 phosphorylation, and these increases were attenuated by resveratrol treatment. In summary, we demonstrate for the first time that resveratrol inhibits IL-6-induced ICAM-1 gene expression, in part, by interfering with Rac-mediated pathways via the attenuation of STAT3 phosphorylation. This study therefore provides important new insights that may contribute to the proposed beneficial effects of resveratrol in endothelial responses to cytokines during inflammation.

Stress fracture at the junction of the middle and distal third of the ulnar diaphysis in a spinner bowler: a case report and a review of the literature

Stress fractures of the ulnar shaft are uncommon injuries, which have been documented in a variety of sports. The location of the fracture is influenced by the activity and mechanism of injury with which it is associated. The combined traditional approach of clinical history, physical examination, plain radiographs and nuclear scintigraphy for unusual stress fracture may be troublesome. This report is the first to describe a stress fracture at the junction of the middle and distal third of the ulnar diaphysis in a bowler due to chronic torsional stress. We discuss the possible mechanism of injury and describe the diagnostic imaging. A review of the literature is also given and compared with the findings and data of this case.

Expression changes of gelatinases in human osteoarthritic knees and arthroscopic debridement

PURPOSE

The purpose of this study was to quantify the expression changes of gelatinase-A and -B (matrix metalloproteinase [MMP]-2 and MMP-9) in a series of chondral, meniscal, and synovial cultures of knee osteoarthritis (OA) for investigation of the possible roles of the cartilage, menisci, and synovia and the efficacy of arthroscopic debridement.

TYPE OF STUDY

A biochemical study.

METHODS

In 43 consecutive patients with knee OA undergoing arthroscopic debridement, we examined the amount of MMP-2 and MMP-9 in a series of chondral, meniscal, and synovial cultures. We also compared the gene expressions of MMP-2 and MMP-9 and membrane-type 1 MMP (MT1-MMP) in the chondral, meniscal, and synovial cultures using reverse transcription polymerase chain reaction (RT-PCR).

RESULTS

Latent and activated forms of MMP-2 were produced in all series of chondral, meniscal, and synovial cultures, and the levels in lesional cultures were significantly higher than those in paralesional ones (P <.001). Moreover, the latent form of MMP-9 (proMMP-9) appeared in 29 of 37 series of synovial cultures and in 13 of 40 series of meniscal cultures. In meniscal cultures after 24 hours of incubation and synovial cultures after 3 and 24 hours of incubation, the level of proMMP-9 in lesional cultures was significantly higher than that in paralesional ones (P <.001). The activated form of MMP-9 appeared in 10 of 37 series of synovial cultures, and the level in lesional cultures was significantly higher than that in paralesional ones (P <.05). Furthermore, MMP-2, -9, and MT1-MMP mRNA levels of lesional areas also showed the increased expression in RT-PCR.

CONCLUSIONS

Our data confirm that tissue repair of OA is ascribable to enzymic digestion of the extracellular matrix ex vivo. When technically appropriate, arthroscopic debridement for the pathologic lesions of OA, such as meniscal tears, chondral lesions, and hypertrophic villi, may be beneficial to the process of early cases. Still, it should be carefully studied for its overall effect and mechanism in vivo.

CLINICAL RELEVANCE

The effectiveness of arthroscopic debridement for the treatment of knee OA is controversial. The present study provides the possible mechanism of the positive effects of arthroscopic debridement in basic science.

The validity of eye blink rate in Chinese adults for the diagnosis of Parkinson's disease

We evaluated the eye blink rate (EBR) in healthy Chinese adults and Parkinson's disease (PD) patients. In healthy subjects, the EBR declined with age, was lower in women than men younger than 50 years of age, and did not differ from male PD patients older than 60 years or female PD patients older than 50 years. Accordingly, EBR is not a good indicator for bradykinesia in Chinese individual older than 50 years that is prevalent for PD onset also.

Nasal schwannoma: a case report and clinicopathologic analysis

According to the literature, half of the schwannoma cases occur in the head and neck areas and only less than 4% occur in the sinonasal tract. In this case, a 39-year-old male patient, with a-year-long progressive left side nasal obstruction and purulent rhinorrhea, is presented. The CT reveals a mass filling the left nasal cavity and nasopharyngeal space, with bony erosion of the inferior turbinate and medial maxillary bone. During surgical intervention, the mass is found to originate from the medial side of the left middle turbinate with maxillary sinusitis and inferior turbinate atrophy. The pathological examination reveals a noncapsulated tumor with palisading cellular arrangement and high cellular density. The pathological findings and nervous origin of the tumor are discussed after an extensive review of the literature.

Prevalence and relationship between allergic diseases and infectious diseases

In order to determine the prevalence of childhood allergic diseases, infectious diseases, and the relationship between them, 8723 children from three junior high schools in Tou-Cheng City, Taipei County, were studied using questionnaires developed according to the International Study of Asthma and Allergies in Childhood (ISAAC) criteria combined with supplementary questions about infectious diseases. Students and their parents completed the questionnaires at home. The age of the children ranged from 10 to 18 years old (14.12 +/- 0.89 years), the majority (96.03%) was aged from 13 to 15 years old. The 12-month prevalences of self-reported allergic disease symptoms were: asthma symptom 8.2%, allergic rhinitis symptom 39.6%, and atopic dermatitis symptom 5.9%. The prevalences of diagnosis of the allergic diseases were: asthma 8.7%, allergic rhinitis 24.1%, and atopic dermatitis 3.9%. The 12-month prevalences of diagnosis of infectious diseases were: pneumonia 0.6%, bronchitis 7.2%, sinusitis 7.2%, purulent conjunctivitis 2.5%, otitis media 4.3%, encephalitis or meningitis 0.4%, gastroenteritis 14.5%, acne 23.9%, purulent dermatitis 1.3%, and other infectious diseases 1.2%. Lifetime admission rates of children due to infectious diseases were: pneumonia 1%, bronchitis 1.8%, sinusitis 0.3%, purulent conjunctivitis 0.2%, otitis media 0.3%, encephalitis or meningitis 0.3%, gastroenteritis 2.1%, and other infectious diseases 0.6%. The prevalence of infectious diseases was significantly higher in children with allergic disease symptoms (defined as asthma, allergic rhinitis, or atopic dermatitis). These results demonstrated the presence of a link between allergic diseases and infectious diseases, which may have some important clinical implications.

Cytotoxic constituents of Polyalthia longifolia var. pendula

A new halimane diterpene, 3beta,5beta, 16alpha-trihydroxyhalima-13(14)-en-15,16-olide (1), and a new oxoprotoberberine alkaloid, (-)-8-oxopolyalthiaine (2), along with 20 known compounds, were isolated from a methanolic extract of Polyalthia longifolia var. pendula. The structures of compounds 1 and 2 were established by spectroscopic analysis. Several of these compounds were evaluated for cytotoxicity toward a small panel of human cell lines.

Investigation into the presence of insulin-degrading enzyme in cultured type II alveolar cells and the effects of enzyme inhibitors on pulmonary bioavailability of insulin in rats

The purpose of this study was to investigate the role of insulin-degrading enzyme (IDE, EC 3.4.22.11) in insulin degradation in alveolar epithelium. The primary culture of isolated rat type-II pneumocytes was used for the in-vitro characterization of IDE. Insulin was then administered intratracheally with various inhibitors to assess the improvement in its pulmonary bioavailability. In cultured type-II pneumocytes, the cytosolic insulin-degrading activity contributed 81% of total insulin degradation, reached a maximum at pH 7.5 and had an apparent Michaelis-Menten constant (Km) of 135 nM. N-Ethylmaleimide, p-chloromercuribenzoic acid and 1,10-phenanthroline inhibited insulin-degrading activity almost completely in both crude homogenate and cytosol. An immunoprecipitation study showed that IDE contributed 74% of cytosolic insulin-degrading activity. Western blot analysis showing a single band of 110 kDa on reduced SDS (sodium dodecylsulphate) gels confirmed the presence of IDE in cultured type-II cells. When given intratracheally with insulin, inhibitors including N-ethylmaleimide, p-chloromercuribenzoic acid, and 1,10-phenanthroline significantly enhanced the absolute bioavailability of insulin and the compound's hypoglycaemic effects. These results suggest that IDE is present in alveolar epithelium and might be involved in limiting insulin absorption in the lung.

Effect of cAMP elevating agents on carbachol-induced phosphoinositide hydrolysis and calcium mobilization in cultured canine tracheal smooth muscle cells

The effects of increases in intracellular adenosine 3',5'-cyclic monophosphate (cAMP) on carbachol-induced generation of inositol phosphates (IPs) and increases in intracellular Ca2+ ([Ca2+]i) were investigated in canine cultured tracheal smooth muscle cells (TSMCs). The cAMP elevating agents, cholera toxin (CTX) and forskolin, induced concentration- and time-dependent cAMP formation with half-maximal effects (-logEC50) at concentrations of 7.6 +/- 1.3 g/ml and 4.8 +/- 0.9 M, respectively. Forskolin caused a concentration-dependent inhibition of carbachol-induced increase in [Ca2+]i with half-maximal inhibition (-logEC50) at 5.2 +/- 0.7 M. Pretreatment of TSMCs with either CTX (10 micrograms/ml, 4 h), forskolin (10-100 microM, 30 min), or dibutyryl cAMP (1 mM, 30 min) inhibited carbachol-stimulated Ca2+ mobilization and IPs accumulation. The inhibitory effects of these agents produced both depression of the maximal response and a shift to the right of the concentration-response curve of carbachol without changing the EC50 values. After treatment with forskolin for 24 h, carbachol-induced IPs accumulation and Ca2+ mobilization were close to those of control group. SQ-22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine, 10 microM], an inhibitor of adenylate cyclase, and HA-1004 [N-(2-guanidinoethyl)-5-isoquinolinesulfonamide hydrochloride, 50 microM], an inhibitor of cAMP-dependent protein kinase (PKA), attenuated the ability of forskolin to inhibit carbachol-induced IPs accumulation. Moreover, the inactive analogue of forskolin, 1,9-dideoxy forskolin, did not inhibit these responses evoked by carbachol, suggesting that activation of cAMP/PKA was involved in these inhibitory effects of forskolin. The KD and Bmax values of the muscarinic receptor (mAChR) for [3H]-N-methyl scopolamine binding were not significantly changed by forskolin treatment for 30 min and 24 h, suggesting that the inhibitory effect of forskolin is distal to the mAChR. The locus of this inhibition was further investigated by examining the effect of forskolin treatment on AIF4(-)-stimulated IPs accumulation in canine TSMCs. The AIF4(-)-induced response was inhibited by forskolin, supporting the notion that G protein(s) are directly activated by AIF4- and uncoupled to phospholipase C by forskolin treatment. We conclude that cAMP elevating agents inhibit carbachol-stimulated generation of IPs and Ca2+ mobilization in canine cultured TSMCs. Since generation of IPs and increases in [Ca2+]i are very early events in the activation of mAChRs, attenuation of these events by cAMP elevating agents might well contribute to the inhibitory effect of cAMP on tracheal smooth muscle formation.

The human immunodeficiency virus type 1 Tat antagonist, Ro 5-3335, predominantly inhibits transcription initiation from the viral promoter

Tat, the transcriptional transactivator protein of the human immunodeficiency virus type 1 (HIV-1), is required for viral replication in vitro. The Tat antagonist, Ro 5-3335, and its analog, Ro 24-7429, have been shown to inhibit replication of HIV-1 and to reduce steady-state viral RNA in infected cells (M.-C. Hsu et al., Science 254:1799-1802, 1991, and M.-C. Hsu et al., Proc. Natl. Acad. Sci. USA 90:6395-6399, 1993). Analysis of HIV-1 long terminal repeat-driven reporter gene transcription in a recombinant adenovirus by nuclear run-on assay indicated that the drug predominantly inhibits Tat-dependent initiation and also exerts a measurable effect on elongation. This result may imply a common mechanism for Tat-mediated transcription initiation and elongation.

Combinative interactions of a human immunodeficiency virus (HIV) Tat antagonist with HIV reverse transcriptase inhibitors and an HIV protease inhibitor

Combinations of the human immunodeficiency virus (HIV) Tat protein antagonist Ro 24-7429 with either the HIV protease inhibitor Ro 31-8959 or the HIV reverse transcriptase inhibitors AZT (3'-azido-3'-deoxythymidine), ddC (2',3'-dideoxycytidine), ddI (2',3'-dideoxyinosine), and nevirapine were synergistic or additive in reducing HIV type 1 p24 antigen production in CEM cells or inhibiting HIV type 1-induced syncytium formation in HT4-6C cells.

Inhibition of type 1 human immunodeficiency virus replication by a tat antagonist to which the virus remains sensitive after prolonged exposure in vitro

The transactivator of transcription, Tat, of human immunodeficiency virus type 1 (HIV-1) is required for viral replication. Inhibition of Tat function could have the potential to keep integrated provirus in dormancy. In the presence of Tat, Ro 24-7429, an analog of Ro 5-3335, inhibited expression of indicator genes controlled by the HIV-1 long terminal repeat promoter in transient transfection assays and in a constitutive cell line at noncytotoxic concentrations. Reduction of steady-state mRNA of the indicator gene by the compound correlated with reduction of the gene product in the constitutive cell line. Ro 24-7429 has broad activity against several strains of HIV-1 in different cell lines, peripheral blood lymphocytes, and macrophages (IC90 = 1-3 microM). Importantly, Ro 24-7429 inhibited viral replication in both acute and chronic infection in vitro, a characteristic expected of a Tat antagonist and not shared by viral reverse transcriptase inhibitors. Consistent with this, the compound reduced cell-associated viral RNA and proteins and partially restored cell-surface CD4 in chronically infected cells. After 2 years of continued weekly passage of the virus in fresh CEM cells grown in the presence of the compound at 1 or 10 microM, the virus did not develop resistance to the drug. These results indicate that the compound's action might involve a cellular factor.

Norplant-2 subdermal contraceptive system: experience in Taiwan

Subdermal Norplant-2 implantation, developed for contraception based on sustained release of levonorgestrel, has already been conducted in many countries around the world. From October 1986 to November 1988, a total of 267 female volunteers were enrolled in Norplant studies at the National Taiwan University Hospital. After a follow-up of 36 months, only one of the 231 evaluable cases (0.4%) became pregnant. The continuation rate was 84.5%, 61.3%, and 52.0% at the end of 12, 24 and 36 months after insertion, respectively. Menstrual problems were the most common adverse effects and were also the main reason for discontinuation. In the 23 patients who wished to become pregnant, fertility occurred soon after removal of the Norplant implant. After insertion, serum total cholesterol and triglyceride levels significantly decreased and the hemoglobin concentrations were increased. No liver or renal toxicities were detected. The data suggest that Norplant-2 is a highly effective, safe and long-acting method of reversible contraception. It would be worthwhile to introduce this contraceptive system into Taiwan's family planning program.

Characterization of recombinant HIV-1 Tat and its interaction with TAR RNA

Recombinant HIV-1 Tat (Tat 1-86) has been purified from the cytoplasmic fraction of Escherichia coli without the use of protein denaturants or chaotropic agents. Chloroquine-mediated uptake of the purified protein into cells resulted in transactivation of the HIV LTR promoter. Tat retains 1.64 mol of Zn2+/mol of protein by atomic absorption spectroscopy. Circular dichroism measurements indicated that the structure of recombinant Tat contains 15-20% alpha-helix. Filter binding assays showed that Tat binds to a 63-nucleotide target TAR RNA with a dissociation constant (Kd) of 10 nM at 25 degrees C, 0.05 M ionic strength, pH 7.5, in a 1:1 Tat-TAR RNA stoichiometry. Nonelectrostatic interactions provide the principal source of free energy of association. While the pH optimum occurs over a wide H+ concentration, the salt dependence of Kd indicates formation of a single ion pair. UV-induced protein-RNA cross-linking produced a labeled Tat-TAR RNA adduct, indicating that direct contact occurred between the Tat protein and TAR RNA.

Restoration of cell surface CD4 expression in human immunodeficiency virus type 1-infected cells by treatment with a Tat antagonist

Productive infection of T lymphocytes with human immunodeficiency virus type 1 (HIV-1) is accompanied by a diminution of surface CD4 receptors. Treatment of chronically HIV-1-infected CD4-negative T cells in vitro with the Tat antagonist Ro 5-3335 resulted in a drug dose-dependent decrease in virus protein production and a reciprocal increase in surface CD4 display. The drug-treated cells remained viable, showed significantly reduced levels of the full-length and spliced HIV-1 mRNAs as detected by Northern (RNA) blot hybridization, and maintained integrated HIV-1 DNA. In immunoprecipitation studies with drug-treated cells, the levels of free 55-kDa CD4 protein increased and gp160 complexed with CD4 decreased in amount. These results show for the first time that certain cytopathogenic effects of chronic HIV-1 infection can be reversed by suppressing virus expression.

Column liquid chromatography and microbiological assay compared for determination of cefadroxil preparations

A reversed-phase column liquid chromatographic method was developed for the assay of cefadroxil in bulk drugs and pharmaceutical preparations. An equation was derived showing a linear relationship between peak-area ratios of cefadroxil to dimethylphthalate (internal standard) and the cefadroxil concentration over a range of 0.02-0.8 mg/ml (r = 0.9999). Standard addition recoveries were generally greater than 97.7%. The coefficients of variation in the within-day assay were between 0.36 and 0.65, and in the between-day assay was 0.71%. The column liquid chromatographic assay results were compared with those obtained from a microbiological assay, which indicated that the proposed method is a suitable substitute for the microbiological method for potency assays and stability studies of cefadroxil preparations.

High-performance liquid chromatographic method for potency determination of amoxicillin in commercial preparations and for stability studies

A reversed-phase column liquid chromatographic method was developed for the assay of amoxicillin and its preparations. The linear calibration range was 0.2 to 2.0 mg/ml (r = 0.9998), and recoveries were generally greater than 99%. The high-performance liquid chromatographic assay results were compared with those obtained from a microbiological assay of bulk drug substance and capsule, injection, and granule formulations containing amoxicillin and degraded amoxicillin. At the 99% confidence level, no significant intermethod differences were noted for the paired results. Commercial formulations were also analyzed, and the results obtained by the proposed method closely agreed with those found by the microbiological method. The results indicated that the proposed method is a suitable substitute for the microbiological method for assays and stability studies of amoxicillin preparations.

Discovery and characterization of an HIV-1 Tat antagonist

Ro 5-3335, 7-chloro-5-(2-pyrryl)-3H-1,4-benzo-diazepin-2-(H)-one, has been shown to inhibit gene expression controlled by the human immunodeficiency virus-1 (HIV-1) LTR promoter. The inhibition was specific for the viral transcriptional transactivator Tat. The compound did not inhibit the basal activity of the HIV-1 LTR or the activity of promoters not responsive to Tat. Consistent with its mode of action, Ro 5-3335 inhibited HIV-1 replication (IC50 = 0.1-1 microM) by reducing viral RNA synthesis in acutely, as well as chronically, infected cells in vitro. The compound was active against HIV-1 and HIV-2, and AZT-resistant clinical isolates.

Inhibition of HIV replication in acute and chronic infections in vitro by a Tat antagonist

The human immunodeficiency virus-1 (HIV-1) trans-activator Tat is an attractive target for the development of antiviral drugs because inhibition of Tat would arrest the virus at an early stage. The drug Ro 5-3335 [7-chloro-5-(2-pyrryl)-3H-1,4-benzodiazepine-2(H)-one], inhibited gene expression by HIV-1 at the level of transcriptional trans-activation by Tat. The compound did not inhibit the basal activity of the promoter. Both Tat and its target sequence TAR were required for the observed inhibitory activity. Ro 5-3335 reduced the amount of cell-associated viral RNA and antigen in acutely, as well as in chronically infected cells in vitro (median inhibition concentration 0.1 to 1 micromolar). Effective inhibition of viral replication was also observed 24 hours after cells were transfected with infectious recombinant HIV-1 DNA. The compound was active against both HIV-1 and HIV-2 and against 3'-azido-3'-deoxythymidine (AZT)-resistant clinical isolates.

Purification and characterization of recombinant Rev protein of human immunodeficiency virus type 1

Recombinant Rev protein of human immunodeficiency virus type 1 has been expressed in Escherichia coli and purified by ion-exchange and gel-filtration chromatography. Specific binding of the purified protein to the Rev-responsive element of the viral RNA is demonstrated. Physical characterization of the purified protein by circular dichroism and intrinsic fluorescence spectroscopy indicate that the protein preparation is suitable for structural analysis. Circular dichroism measurements show that the protein is approximately 40-45% alpha-helix. Tryptophan fluorescence measurements suggest that the single tryptophan residue is located near the surface of the protein. Gel-filtration chromatography of the protein indicates that it has an apparent molecular mass of 33,000 daltons. This suggests that the protein in solution forms a stable tetramer consisting of monomers having molecular mass of 13,000 daltons.

Hypertensive disorders in pregnancy: analysis of 110 cases

One hundred and ten cases of hypertensive disorders in pregnancy were analyzed retrospectively. There were 16 cases of gestational hypertension, 36 cases of mild preeclampsia, 43 cases of severe preeclampsia, 6 cases of eclampsia, and 9 cases of chronic hypertension with superimposed severe preeclampsia. The principle of management was conservative in order to prolong pregnancy for patients remote from term. Corticosteroids were used to accelerate fetal lung maturity for patients with gestations of less than 36 weeks and magnesium sulfate was administered to prevent seizures. Fetal heart rate monitoring was done routinely and doppler blood flow velocity time wave form study of uterine and umbilical arteries was also performed in the latter part of the study. The cesarean section rate in gestational hypertension and mild preeclampsia was comparable to the general obstetric population in our institute (26.9% vs. 21.2%), but the rate of severe forms of the disease including severe preeclampsia, eclampsia, and chronic hypertension with superimposed severe preeclampsia was as high as 77.6%. Fetal distress was the main indication of section. There were 2 cases (6.9%) of mild respiratory distress syndrome, and all recovered uneventfully. The patients with severe forms of the disease had a higher incidence of small infants for gestational age (72%) and delivery at less than 36 weeks' gestation (48.2%). The corrected perinatal mortality rate was 5.4%. No maternal death was encountered. It was concluded that pregnancy could be prolonged in the interest of fetal lung maturity under meticulous maternal-fetal monitoring without endangering the mother.

Photoaffinity labeling of human placental monoamine oxidase-A by 4-fluoro-3-nitrophenyl azide

Our previous work has shown that low concentrations of 4-fluoro-3-nitrophenyl azide (FNPA) (0.01-1 microM) photodependently inhibited only the type B monoamine oxidase in rat brain [Biochem. Pharmacol. 34:781-785 (1985)]. Evidence is presented in this paper indicating that higher concentrations of FNPA (15 microM) photodependently inhibit type A monoamine oxidase (MAO-A) from human placenta. FNPA acted as a competitive inhibitor for human placental MAO-A in the dark (Ki = 10 microM) when [14C]serotonin was used as the substrate. The inhibition of MAO-A activity by FNPA was concentration dependent and also irradiation time dependent. The specificity of the photodependent incorporation of FNPA to MAO-A was shown by the protective effect of serotonin during the irradiation. The kinetic analysis showed that the Vmax was decreased whereas the Km was not changed after FNPA was photolyzed with MAO-A. Furthermore, there was no recovery of MAO-A activity upon washing of the photolyzed FNPA-enzyme mixture. These results suggest that FNPA may be covalently bound to the substrate-binding site. Thus, under the present experimental conditions, FNPA is a suitable photoaffinity labeling probe for human placental MAO-A. This is the first photoaffinity label for MAO-A, which may be useful for characterizing the substrate-binding site of this enzyme.

Assessment of the pathogenetic role of physical exercise in renal stone formation

The effects of moderate physical exercise (performed on a bicycle ergometer to 70-75% of maximum oxygen consumption) without fluid replenishment on urinary chemistries and crystallization of kidney stone-forming substances were compared to those of rest in six normal subjects. Moderate physical exercise significantly decreased urinary pH [from 6.35 +/- 0.32 (+/-SD) to 5.79 +/- 0.33; P less than 0.05] and citrate [from 121.1 +/- 63.5 to 88.2 +/- 44.4 mg/6-h period from initiation of physical exercise; P less than 0.05 (630 +/- 331 to 459 +/- 231 mumol/6 h)], owing to induced metabolic acidosis. The total renal excretion of stone-forming constituents decreased [for example, calcium from 31.2 +/- 15.8 to 21.4 +/- 6.5 mg/6 h (0.8 +/- 0.4 to 0.5 +/- 0.2 mmol/6 h), phosphorus from 155 +/- 42 to 127 +/- 27 mg/6 h (5.01 +/- 1.4 to 4.1 +/- 0.9 mmol/6 h), and uric acid from 172 +/- 60 to 117 +/- 13 mg/6 h (1.0 +/- 0.4 to 0.7 +/- 0.1 mmol/6 h), each P less than 0.05], probably due to extracellular volume contraction (from sweating) and enhanced renal tubular reabsorption. However, the urinary concentration of stone-forming constituents significantly increased during and after moderate exercise because of the fall in urinary volume from 847 +/- 312 to 290 +/- 36 ml/6 h (P less than 0.01). Thus, urinary calcium oxalate saturation increased significantly from 2.62- to 6.68-fold saturation (P less than 0.01). The urinary undissociated uric acid concentration significantly rose [from 31.6 +/- 24.8 to 125.7 +/- 60.3 mg/L (0.19 +/- 0.15 to 0.76 +/- 0.36 mmol/L; P less than 0.01)], due to higher total uric acid concentration and reduced urinary pH. The saturation of calcium phosphate (brushite) did not change significantly, because the rise in urinary calcium concentration was compensated for by reduced phosphate dissociation (from lower urinary pH). The propensity for spontaneous precipitation of calcium oxalate was greater after exercise, as less soluble oxalate was required to elicit nucleation of calcium oxalate [58.0 +/- 21.2 to 49.0 +/- 16.4 mg/L (644 +/- 236 to 544 +/- 182 mumol/L); P less than 0.05]. The results suggest that moderate physical exercise, without increased fluid intake to compensate for excessive sweating, may cause the crystallization of uric acid and calcium oxalate in urine and may enhance the risk of the formation of renal stones composed of these salts.

Enhanced calcium bioavailability from a solubilized form of calcium citrate

An improved formulation of calcium citrate with higher aqueous solubility and bioavailability was sought. Mixtures of calcium hydroxide and citric acid, with a calcium to citrate molar ratio ranging from 0.67-1.5, dissolved rapidly in water, creating a metastably supersaturated solution. The presence of an excess of citrate in the mixture delayed the precipitation of calcium citrate and kept calcium in solution longer. Thus, the mixture with a calcium to citrate molar ratio of 1.25, containing 500 mg elemental calcium, dissolved in 300 mL water within 2 min and could be kept in solution for 1 h at a wide pH range between 2 and 7. Intestinal calcium absorption, measured from the increment in urinary calcium during the second 2 h following an oral calcium load (500 mg) in 15 normal subjects was significantly higher from the mixtures (calcium to citrate molar ratios of 1.5 and 1.25) than from tricalcium dicitrate. The fractional calcium absorption, obtained from fecal recovery of radiocalcium after oral administration of 500 mg calcium prelabeled with 47Ca in 11 normal subjects, was also higher for the mixture with a calcium to citrate molar ratio of 1.25. The most efficient calcium absorption was obtained with the mixture of calcium hydroxide and citric acid with a calcium to citrate molar ratio of 1.25. The increment in urinary calcium after an oral load with this mixture was 62.4% greater than that obtained with tricalcium dicitrate [0.138 +/- 0.056 (+/- SD) vs. 0.085 +/- 0.086 mg/dL glomerular filtrate; P less than 0.05]. The fractional calcium absorption was 88.4% higher (0.324 +/- 0.107 vs. 0.172 +/- 0.061; P less than 0.05). This mixture provided the highest concentration of ionic calcium, indicating that calcium (rather than calcium-citrate complex) is the fraction absorbed from the intestinal tract. This study, therefore, suggests that a liquid calcium preparation formulated from the mixture of calcium hydroxide and citric acid is more effective than a solid preparation of tricalcium dicitrate in providing soluble and bioavailable calcium.

Variability of tobramycin pharmacokinetics in cystic fibrosis

This study determined the extent and impact of tobramycin pharmacokinetic variability in cystic fibrosis patients. Twenty patients were hospitalized twice and the tobramycin half-life, volume of distribution and clearance were determined during Weeks 1 and 2 of both admissions. A difference (P less than 0.05) existed between Weeks 1 and 2 of each admission, but not between admissions, for the clearance and half-life. No difference existed between weeks or admissions for the volume of distribution. No significant correlations existed between weeks within an admission for the half-life and clearance. There was a significant correlation for the volume of distribution between Weeks 1 and 2 of the second admission but not for the first admission. The percents of coefficient of variation and ranges were large. With dosing regimens derived from previously determined factors, "within admission" predicted peaks and troughs would result in 60 and 35% of patients outside the therapeutic range for Admissions 1 and 2, respectively. "Between admission" predictions would result in 65 and 75% of patients outside the therapeutic range. We conclude that considerable variability exists and recommend weekly determinations of serum concentrations and dosing adjustments.

The preservation of urine samples for determination of renal stone risk factors

A preservation technique for urine specimens before determination of stone risk factors was evaluated. The purpose of these experiments was to prove the effectiveness of the preservatives used to prevent changes in the concentrations of those constituents measured. Measured concentrations in fresh specimens were compared with those in the same specimens after storage with the preservatives. Refrigeration at 4 degrees C up to five days was appropriate in a laboratory setting, as no significant changes in urinary concentrations occurred. Refrigeration, however, did not offer a convenient method for shipping. Chemical preservation was found to be an effective alternative to refrigeration. Thymol prevented changes in concentration of pH, citrate, uric acid, sulfate, sodium, potassium, and cyclic AMP, while a mixture of hydrochloric (HCl) acid and boric acid prevented changes in calcium, magnesium, phosphorus, oxalate, ammonium, and creatinine. Thus, the addition of thymol or HCl/boric acid to urine specimens will prevent significant changes in the concentrations of stone risk factors.

Photoaffinity labeling of beef liver monoamine oxidase-B by 4-fluoro-3-nitrophenyl azide

4-Fluoro-3-nitrophenyl azide (FNPA) competitively inhibited beef liver monoamine oxidase-B (MAO-B) in the dark (Ki = 2.8 microM). Upon irradiation in the presence of FNPA, a concentration-dependent photoinactivation of MAO-B was observed. The kinetic analysis showed that the photoinactivation of MAO-B resulted in a decrease in Vmax but no change in Km. This result suggests that an irreversible linkage may be formed between the enzyme and the photolyzed FNPA. When [3H]FNPA was photoirradiated with the purified MAO-B, a single radioactive band associated with MAO-B was observed by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The photo-dependent incorporation could be protected by phenylethylamine, the substrate for MAO-B, in a concentration-dependent manner. Complete tryptic-chymotryptic digestion of [3H]FNPA-labeled MAO-B resulted in three radioactive peaks on Sephadex G-25 column chromatography. With the same digestion and separation procedures, only one major radioactive peak was observed for the [3H]pargyline-labeled MAO-B, and its elution volume was different from that of [3H]FNPA-labeled peptides. These results suggest that, upon photolysis, FNPA may incorporate into a region in the active site of MAO-B which may be different from the pargyline binding site--the FAD prosthetic group of the enzyme.

Protease activation mutants of Sendai virus: sequence analysis of the mRNA of the fusion protein (F) gene and direct identification of the cleavage-activation site

Trypsin cleaves the fusion protein (F) of wild-type Sendai virus into two disulfide-linked polypeptides, F1 and F2, and thereby activates the membrane fusion activity of the virus. A. Scheid and P.W. Choppin [1976). Virology, 265-277) selected mutant viruses of which the F protein could be activated by different proteases, either elastase, chymotrypsin, or plasmin. Herein, we have further characterized five of these mutants. Sequencing of each mutant mRNA encoding the 60-70 amino acids surrounding the cleavage site revealed one or two amino acid changes near or at the cleavage sites. Virions cleaved in vitro by the appropriate proteases were assayed of their fusion activity by hemolysis, and the cleavage sites were determined by amino acid sequencing. In three cases, the change of protease specificity can be accounted for by changed amino acids right at the cleavage site, whereas several other mutations that potentiate cleavage at new sites by new proteases are somewhat removed from the actual cleavage site. We surmise that such mutations might alter local polypeptide conformation, thereby allowing the proteases access to existing sites. Cleavage at new sites produced fusion proteins with novel F1 NH-termini. We found that a mutant with a charged residue at the third position of this normally hydrophobic NH-terminal sequence retains activity in the hemolysis assay, whereas a mutant with a charged residue at the first position does not.

Attainment of therapeutic fluoride levels in serum without major side effects using a slow-release preparation of sodium fluoride in postmenopausal osteoporosis

The bioavailability, biochemical effects, and safety of a slow-release preparation of sodium fluoride were examined. In 8 normal volunteers, a single administration of slow-release sodium fluoride (25 mg) caused a slow rise and gradual decline in serum fluoride concentration, thus avoiding sharp peaks produced by a rapid-release preparation. In 37 patients with postmenopausal osteoporosis, serum fluoride concentration was kept within the "therapeutic window" (95-100 ng/ml) during long-term intermittent sodium fluoride (slow-release) therapy (25 mg twice/day, given for 3 months in each 5-month cycle over five cycles). Serum fluoride was also kept within the therapeutic window in 64 patients who took sodium fluoride (slow release) continuously over 12 months. Serum osteocalcin concentration increased progressively during fluoride treatment (correlation coefficient of 0.88, p less than .001 for the relationship between serum osteocalcin and duration of therapy). Side effects to slow-release sodium fluoride therapy, assessed in 101 patients at two study sites, were minor and included diarrhea in 2 patients, nausea in 2 patients, abdominal pain and cramping in 2 patients, foot pain in 2 patients, and joint pain in 6 patients. Thus, slow-release sodium fluoride confers desired level of fluoride in serum, while providing safety of usage.

The fusion-related hydrophobic domain of Sendai F protein can be moved through the cytoplasmic membrane of Escherichia coli

Recent work on a prokaryotic membrane protein, gene III protein (pIII) of coliphage f1, showed that polypeptide segments of sufficient hydrophobicity functioned to stop transfer of the polypeptide across the cell membrane: strings of 16 or more hydrophobic amino acids sufficed. A fusion-related hydrophobic domain (FRHD) of Sendai F protein, a sequence of 26 consecutive uncharged residues, has been implicated in the fusion of the viral membrane envelope and the target-cell membrane through a hydrophobic interaction. As it is located on the exterior of the viral membrane, this sequence must be transferred across the host-cell membrane during synthesis. We have inserted either the FRHD or the F protein membrane anchor (the COOH-terminal region of the F protein) into an internal site of a secreted pIII, which lacks its natural membrane anchor. These two hydrophobic sequences behave in the bacteria just as they do in their natural eukaryotic cell host. The F protein membrane anchor functions to stop transfer, conferring a membrane-spanning topology to the F-pIII hybrid protein; however, the FRHD is moved through the cytoplasmic membrane and derivatives carrying this sequence are secreted to the periplasm. We discuss how the FRHD is compatible with passage through the membrane and yet is still able to mediate membrane fusion through a presumed hydrophobic interaction.

Studies on taeniasis in Taiwan. V. Field trial on evaluation of therapeutic efficacy of mebendazole and praziquantel against taeniasis

Taeniasis is a major public health problem among the aboriginal populations on Taiwan, and is highly prevalent and wide spread in the mountain areas of 10 Counties. Over 27,000 cases of tapeworm infection are estimated influencing the health and economy in the endemic areas. A treatment of taeniasis with mebendazole and praziquantel followed by a re-treatment with atabrine has been done in the field trial, and confirmed that praziquantel is highly effective agent against tapeworm infection, but mebendazole is not. Based upon experiments reported here praziquantel in a single dose of 150 mg, and 450 mg are highly effective against taeniasis and hymenolepiasis respectively.

Individualization of tobramycin dosage in patients with cystic fibrosis

Tobramycin was administered to 52 patients, ages 2 months to 27 years, with cystic fibrosis during acute exacerbation of Pseudomonas-related pulmonary infection. Elimination pharmacokinetics of tobramycin was characterized for each patient after intravenous administration using a standardized infusion technique. The minimal inhibitory concentration was determined for Pseudomonas strains isolated from 26 of the 52 patients. The pharmacokinetic parameters of individual patient were used to adjust the dose and dosing interval to maintain the serum concentration of tobramycin above the minimal inhibitory concentration for the infecting organism for at least 75% of the dosing interval without exceeding the maximum concentration of 12 micrograms/ml or a minimum concentration of 2.0 micrograms/ml. This resulted in an increase of the mean daily dose of tobramycin to 12 mg/kg from an initial mean dose of 5.5 mg/kg and a reduction of the dosing interval from 8 hours to 4 or 6 hours for patients greater than 1 year of age. Significant differences between the pharmacokinetic profiles of the infants and older patients were observed.

Fusion of Sendai virus with liposomes: dependence on the viral fusion protein (F) and the lipid composition of liposomes

The characteristics of fusion of the membrane of Sendai virus with that of liposomes has been investigated using two different methods to monitor the fusion reaction. The first method, which permits quantitation of lipid fused with virus, depends on separation by centrifugation of unfused liposomes from those fused with virus. The second involves the digestion after fusion of internal viral proteins by trypsin contained in liposomes; this assay is completely independent of exchange of lipid between liposomal and viral membranes in the absence of fusion. A fusion-inactive mutant virus, pa-cl, with an uncleaved F protein served as the appropriate control in these experiments. It was found that fusion of the virus with liposomes that contained no protein required cleavage of the F protein; such cleavage was previously shown to be required for fusion of the virus with cell membranes. This indicates the relevance of this model system for studies of fusion. Kinetic studies indicated that at neutral pH fusion was 88% complete in 10 min at 37 degrees. Investigation of the effects of liposomal lipid composition indicated that the presence of cholesterol in the liposomal membrane was required for fusion; a 0.3-0.4-mole fraction of cholesterol was optimal. The presence of neuraminic acid in the membrane was not essential for fusion. The results obtained are compatible with previous evidence suggesting a hydrophobic interaction between the cleaved F protein and the target membrane during fusion.

Enhancement of membrane-fusing activity of sendai virus by exposure of the virus to basic pH is correlated with a conformational change in the fusion protein

The effect of pH on the membrane-fusion activity of Sendai virus was examined (pH 5.0-9.5) by using, as assays of activity, hemolysis of chicken erythrocytes and the fusion of baby hamster kidney (BHK-21) cells. Exposure of virus to basic pH increased fusion activity; the optimum pH was found to be approximately equal to 9.0. All assays were carried out at pH 7.0, and the virus retained enhanced fusion activity after it was exposed to basic pH and returned to neutral pH. The enhanced fusion activity was correlated with an irreversible conformational change in the fusion protein (F protein) of the virus, as demonstrated by a change in the circular dichroism spectrum of the protein.

Influence of cerebral embolism on brain monoamines

In baboons the right cerebral hemisphere was embolised by a shower of microemboli, immediately followed by one large embolus designed to occlude the middle cerebral artery (MCA). One hour after embolism a significant, though small, reduction in blood flow and oxygen consumption of the embolised hemisphere was recorded, at which time the animals were killed and brain monoamines measured. Dopamine was reduced in the ipsilateral caudate nucleus, the reported site of maximal ischaemic damage in this model. Dopamine levels were increased in frontal and occipital grey matter sampled from areas surrounding the occluded MCA territory and in similar brain areas of the opposite non-embolised hemisphere. Noradrenaline was increased in grey matter from both cerebral hemispheres, as well as subcortical structures bilaterally. Brain 5-hydroxytryptamine levels were unaltered, but increased 5-hydroxyindoleacetic acid in cisternal cerebrospinal fluid suggested transient alteration in 5-hydroxytryptamine metabolism after embolism. The effects of cerebral embolism on brain monoamine metabolism appear to be different from the effects of permanent surgical occlusion of major cerebral vessels. The bilaterality of effects after unilateral hemispheric embolism might be related to diaschisis. The mechanisms of the observed changes, as well as their relevance to the progression of cerebral ischaemia and the complications associated with cerebral embolism, still require to be established.