Permeability of the blood-brain and blood-spinal cord barriers to interferons

Interferons (IFNs) are cytokines that produce effects in the CNS even though their production occurs mainly in the periphery. Direct passage of IFNs from blood to CNS could be an important route by which circulating IFNs exert their central effects. In this report, we characterize the pharmacokinetics of the passage of IFNs through the blood-brain and blood-spinal cord barriers in four separate regions: whole brain and the cervical, thoracic and lumbosacral segments of the spinal cord. We found that the spinal cord had greater permeability to IFNs than did the brain. For each corresponding region, the permeability to IFN alpha was higher than that to IFN gamma. Capillary depletion after cardiac perfusion showed that most of the injected IFN was not entrapped by the vasculature but entered the parenchyma of the brain. HPLC showed that most of the IFN gamma entered in intact form. The passage of radioactively labeled IFN gamma into the brain and cervical spinal cord was saturated by a low dose of unlabeled IFN gamma, while passage into the thoracic and lumbosacral spinal cord was not saturated. In contrast, for another cytokine, tumor necrosis factor alpha (TNF alpha), a saturable transport system was present in distal spinal cord as well as the brain. The results show that IFNs and TNF alpha can enter the CNS from the periphery but with regional differences.

Study of structure-activity correlation in destruxins, a class of cyclodepsipeptides possessing suppressive effect on the generation of hepatitis B virus surface antigen in human hepatoma cells

A new destruxin [destruxin E2 chlorohydrin] was isolated from the culture medium of Metarrhizium anisopliae and its structure was determined by NMR spectroscopy and mass spectrometry. As compared with other destruxins, the new destruxin showed a lower suppressive activity on the production of hepatitis B virus surface antigen in human hepatoma Hep3B cells. NMR study coupled with molecular modeling by computer graphics has revealed that the hydrophobicity nature of the convex surface characteristic of all destruxin molecules plays an important role in their biological activity.

The relationship between surface dust lead loadings on carpets and the blood lead of young children

The final clean-up of residential lead abatement projects in federally-supported housing, as well as in other housing in a number of states, must meet surface dust lead clearance levels expressed as μg of lead per square foot. These clearance levels were established because hand-to-mouth ingestion of lead-contaminated dust is recognised as a major pathway through which many children are exposed. A dilemma exists because many floors in housing undergoing abatement are carpeted and the established clearance levels are generally not recommended for use on carpets. These clearance levels are also used as 'action levels' to determine whether exposure reduction activities are needed. The US Environmental Protection Agency is currently in the process of issuing standards for hazardous levels of lead in interior dust and bare soil under Title X of the Housing and Community Development Act of 1992, 'The Residential Lead-Based Paint Hazard Reduction Act of 1992'. An effort to develop a potential surface dust lead clearance level for carpets was made using an existing vacuum dust collection method that has previously been shown to be a reliable indicator of childhood lead exposure. This method was designed for use on carpeted and non-carpeted surfaces. Using data from the Cincinnati Soil Lead Abatement Demonstration Project, the suggested floor-dust lead level where an estimated 95% of the population of children would be expected to have blood lead values below the national goal of 10 μg dL(-1), was more than an order of magnitude lower than the current floor-dust lead clearance level of 1080 μg m(-2) (100 μg ft(-2)). Further comparisons of blood lead and carpet lead levels in other parts of the country should be performed before a risk-based lead loading clearance level is established.

Regulation of rat liver glucose-6-phosphatase gene expression in different nutritional and hormonal states: gene structure and 5'-flanking sequence

The mRNA level of the catalytic subunit of rat liver glucose-6-phosphatase (Glu-6-Pase) was regulated by hormones commensurate with activity changes in vivo. Insulin exerts a dominant negative effect on the mRNA levels of Glu-6-Pase. Both mRNA levels and activities of the enzyme are low in the fed and refed state where insulin levels are elevated. Insulin administration to diabetic rats also decreases levels of mRNA and Glu-6-Pase activity. Insulin at a concentration of 1 nmol/l completely overcomes the stimulatory effect of glucocorticoids on Glu-6-Pase message levels in FAO hepatoma cells. The stimulatory response to glucocorticoid in FAO cells is biphasic, with maxima seen at 3 and 18 h after hormone addition (respectively 1.6- and 3.3-fold). 8-(4-chlorophenylthio)-cAMP (CPT-cAMP) causes a fourfold increase in Glu-6-Pase mRNA at 3 h in FAO cells. The gene of rat liver Glu-6-Pase is 13 kilobases in length and comprised of 5 exons. The exon-intron structure is completely conserved when compared with the mouse and human genes. A 0.5-kb 3'-untranslated region, which is present in rat and mouse liver Glu-6-Pase cDNA, is absent in the Glu-6-Pase gene reported here, indicating the possible duplication of either the terminal fifth exon or the entire gene. The promoter region contains a consensus core CCAAT element at position -207 and a TATAAA at position -31. Several possible response elements have been identified in the 5'-flanking region (from a HindIII site at position -1641). A consensus glucocorticoid response element is located at base pair -1552, a 9/10 match of the insulin response sequence is located at position -1449, and a 7/8 match of the cAMP response element is located at position -164.

Renal gluconeogenesis and blood flow during endotoxic shock

OBJECTIVES

To determine whether endotoxic shock decreases the renal gluconeogenic capacity and the renal artery blood flow.

METHODS

An in-vivo, murine, nonrecirculating kidney perfusion model was studied in a trauma research laboratory. Each of 12 fasted, male Holtzman rats (shock n = 6, control n = 6) was injected with 1 mL of normal saline or endotoxin (20 mg/kg). Five hours after the injection, all the rats were anesthetized and blood samples were obtained for the determination of the plasma glucose. Right renal artery blood flow was measured by an ultrasonic small-animal flow meter. The kidney was then perfused via the renal artery with 37 degrees C, oxygenated, glucose-free Krebs-Henseleit solution in the presence of 100 mumol of phloridzin to inhibit the cellular uptake of glucose. Renal glucose production was determined by measuring glucose in both renal vein effluent and urine. After 30 minutes of equilibration, 5 mmol of lactate and 0.5 mmol of pyruvate were added to the perfusate as a gluconeogenic substrate. Renal vein and ureteral effluent samples were collected after 5, 10, and 15 minutes.

RESULTS

The endotoxic shock group showed hypoglycemia (p < 0.05) as well as a decrease in renal artery blood flow (p < 0.05). Gluconeogenic stimulation was demonstrable in both the control and the endotoxic shock groups after 15 minutes of perfusion with substrate (p < 0.05). However, renal gluconeogenesis was significantly attenuated in the endotoxic shock group compared with the control.

CONCLUSIONS

Renal glucose production in response to a gluconeogenic substrate is significantly attenuated during the hypoglycemic phase of endotoxic shock. Endotoxic shock also causes a significant decrease of renal artery blood flow.

Differential permeability of the BBB in acute EAE: enhanced transport of TNT-alpha

Impairment of the blood-brain barrier (BBB) in experimental autoimmune encephalomyelitis (EAE) has been frequently attributed to disruption, without much consideration of saturable transport processes. In mice with EAE, we studied the permeability of the BBB to radioactively labeled albumin and sucrose, markers of BBB disruption, and tumor necrosis factor-alpha (TNF-alpha), a cytokine transported across the BBB by a saturable system and thought to play a role in the pathogenesis of EAE. Permeation of the BBB was increased to all three substances during the acutely ill stage, was greatest in the lumbar spine, and returned to normal with recovery. The change in BBB permeability to sucrose was greater than to the larger albumin and is consistent with a partial disruption of the BBB. The enhanced permeability to TNF-alpha was comparable to that for sucrose, even though TNF-alpha is similar in size to albumin. This paradoxically high uptake of TNF-alpha could be explained by an enhancement of its endogenous saturable transport system. Thus the changes in BBB function during EAE extend beyond disruption to include changes in the saturable transport systems for substances involved in the disease process.

DNA segments sensitive to single-strand-specific nucleases are present in chromatin of mitotic cells

It was observed before that DNA in situ in chromatin of mitotic cells is more sensitive to denaturation than DNA in chromatin of interphase cells. DNA sensitivity to denaturation, in these studies, was analyzed by exposing cells to heat or acid and using acridine orange (AO), the metachromatic fluorochrome which can differentially stain double-stranded (ds) vs single-stranded (ss) nucleic acids, as a marker of the degree of DNA denaturation. However, without prior cell treatment with heat or acid no presence of single-stranded DNA in either mitotic or interphase cells was detected by this assay. In the present experiments we demonstrate that DNA in situ in mitotic cells, without any prior treatment that can induce DNA denaturation, is sensitive to ss-specific S1 and mung bean nucleases. Incubation of permeabilized human T cell leukemic MOLT-4, promyelocytic HL-60, histiomonocytic lymphoma U937 cells, or normal PHA-stimulated lymphocytes with S1 or mung bean nucleases generated extensive DNA breakage in mitotic cells. DNA strand breaks were detected using fluorochrome-labeled triphosphonucleotides in the reaction catalyzed by exogenous terminal deoxynucleotidyl transferase. Under identical conditions of the cells' exposure to ss-specific nucleases, DNA breakage in interphase cells was of an order of magnitude less extensive compared to mitotic cells. The data indicate that segments of DNA in mitotic chromosomes, in contrast to interphase cells, may be in a conformation which is sensitive to ss nucleases. This may be a reflection of the differences in the torsional stress of DNA loops between interphase and mitotic chromatin. Namely, greater stress in mitotic loops may lead to formation of the hairpin-loop structures by inverted repeats; such structures are sensitive to ss nucleases. The present method of detection of such segments appears to be more sensitive than the use of AO. The identification of mitotic cells based on sensitivity of their DNA to ss nucleases provides an additional method for their quantification by flow cytometry.

Isolation of virus-neutralizing RNAs from a large pool of random sequences

RNA and ribonuclease-resistant RNA analogs that bound and neutralized Rous sarcoma virus (RSV) were isolated from a large pool of random sequences by multiple cycles of in vitro selection using infectious viral particles. The selected RNA pool of RSV-binding sequences at a concentration of 0.16 microM completely neutralized the virus. Of 19 sequences cloned from the selected pool, 5 inhibited RSV infection. The selected RNA and RNA analogs were shown to neutralize RSV by interacting with the virus, rather than by adversely affecting the host cells. The selection of the anti-RSV RNA and RNA analogs by intact virions immediately suggests the potential application of this approach to develop RNA and RNA analogs as inhibitors of other viruses such as human immunodeficiency virus.

Phosphorylation of F1F0 ATPase delta-subunit is regulated by platelet-derived growth factor in mouse cortical neurons in vitro

The delta subunit of F1F0 ATPase (ATP synthase complex) is part of the stalk connecting the F1 and F0 moieties. Studies in Escherichia coli suggest that the analogous bacterial subunit, called epsilon, is essential for the ATPase assembly energy coupling. Platelet-derived growth factor (PDGF) is an important growth factor for various cell types, including neurons of the CNS. Using two-dimensional gel electrophoresis, microsequencing, western blot analysis, and immunoprecipitation techniques, we have found that PDGF induces phosphorylation of the delta subunit or a closely related peptide in cultured mouse cortical neurons.

Synthesis and application of hepatitis E virus peptides to diagnosis

Based on computer analysis of hydrophobicity and prediction of secondary structures for the full-length putative proteins encoded by open reading frame-1 (ORF-1), ORF-2 and ORF-3 of hepatitis E virus (HEV), we selected antigenic regions with hydrophilicity, beta-turn, and beta-sheet, and synthesized 7 peptides of possible epitope-containing regions of the polypeptide encoded by all 3 ORFs of HEV genomic RNA by Merrifield's method of solid-phase synthesis. The synthetic peptides were screened and identified by solid-phase enzyme-linked immunosorbent assay (ELISA). Three of the peptides (EH174 from ORF-1, EH286 from ORF-2 and EH362 from ORF-3) showed antigenic activity and possible application for the development of anti-HEV test kits (the peptide-based ELISA). The laboratory experiments and clinical trials showed that the kits, using a set of 3 synthetic HEV peptides as coating antigens, were of high specificity and exhibited good reproducibility. The small-scale seroepidemiological survey indicated high seroprevalence (14.3%) of anti-HEV in Tibetan populations. Additionally, the results also demonstrated good agreement with clinical findings, suggesting that the test kits will be of major use for immunodiagnosis and seroepidemiological surveys of HEV infection.

Recommendations for initial antibiotic treatment of extracavitary arterial graft infections

BACKGROUND

Initial antibiotic treatment of extracavitary arterial graft infections is usually empiric or based on Gram's stain findings. Increasing virulence of bacteria causing extracavitary arterial graft infections may render previous choices of antibiotics obsolete. The purposes of this study were to correlate Gram's stain findings of gram-positive bacteria and gram-negative bacteria with wound cultures and provide a microbiologic basis for appropriate initial antibiotic therapy.

METHODS

Between July 1, 1979 and June 30, 1994, specimens obtained on the day of admission from purulent wounds involving 113 extracavitary arterial graft infections were retrospectively reviewed for Gram's stain and culture and sensitivity results.

RESULTS

Gram's stain findings correlated with final cultures on only 28 of 113 cases (25%), including 20 of 48 pure gram-positive, 2 of 24 pure gram-negative, and 6 of 41 mixed bacterial cultures. Staphylococcus aureus was the most common gram-positive bacteria cultured (43 isolates) and Pseudomonas species was the most common gram-negative bacteria (25 isolates). Bacteria were sensitive to a first-generation cephalosporin in only 32% (36 of 113) of infections. A combination of vancomycin and either ticarcillin-clavulanic acid or ceftazidime, which have minimal toxicity and provide excellent coverage against staphylococci, Pseudomonas, and other gram-negative bacteria, would have covered 96% (109) and 95% (107) of cultured organisms, respectively.

CONCLUSIONS

Regardless of Gram's stain findings, current recommendations for initial treatment of extracavitary arterial graft infections should include vancomycin and ceftazidime or ticarcillin-clavulanic acid until final culture and sensitivity results dictate the use of more selective antibiotics.

Alterations in hepatic production and peripheral clearance of IGF-I after endotoxin

Lipopolysaccharide (LPS) produces a rapid and sustained reduction in the circulating concentration of insulin-like growth factor I (IGF-I), which may be responsible, in part, for the alterations in protein metabolism observed in these animals. The purpose of the present study was to determine whether this drop was due to a decreased hepatic production of IGF-I and/or an increased clearance of the peptide from the blood. Four hours after intravenous injection of LPS the plasma IGF-I concentration was decreased 50%. IGF-I release by in situ perfused livers from control rats was constant throughout the 60-min perfusion period and averaged 111 +/- 3 ng/min. In contrast, hepatic IGF-I output was decreased 46% by in vivo LPS. In contrast, livers from LPS-injected rats released more IGF binding proteins-1, -2 and -4 than did control livers. Hepatic cell isolation indicated that LPS decreased the IGF-I content in Kupffer and parenchymal cells, but not endothelial cells, by approximately 45%. Pharmacokinetic analysis of blood 125I-IGF-I decay curves indicated that the half-life for whole body clearance of 125I-IGF-I from the circulation was not altered by LPS. However, LPS increased 125I-IGF-I uptake by spleen, liver, lung, and kidney while decreasing uptake by the pancreas and gastrointestinal tract. These results indicate that the LPS-induced decrease in blood IGF-I concentration is primarily due to a reduction in hepatic production, not a change in whole body peptide clearance, and that a decreased production by both parenchymal and Kupffer cells contributes to this alteration.

Time of symptom onset of eight common medical emergencies

Specific time periods of the day may be associated with different frequencies of symptom onset in different diseases. The purpose of the current study was to examine times of symptom onset in eight commonly encountered emergent conditions--cerebral infarction, cerebral hemorrhage, transient ischemic attacks, cardiac dysrhythmias, angina pectoris, acute myocardial infarction, gastrointestinal bleeding, and acute asthma. Data from 4554 cases were retrospectively reviewed. Symptom onset frequency curve diagrams were derived, illustrating peak hours of symptom presentation for each of the eight emergent conditions. Hormonal and metabolic factors that may be related to diurnal variations in symptom onset of the eight diseases are briefly discussed.

Serological survey of nasopharyngeal carcinoma in 21 cities of south China

This paper reports the results of serological survey of 318,912 persons for nasopharyngeal carcinoma (NPC) in 21 cities and counties of south China. There were 8,441 persons with positive VCA-IgA antibody (single item positive) of EB virus (EBV), with a rate of 2.65%. In these VCA-IgA positive persons, 287 persons also had positive EA-IgA (double items positive) of EBV. The overall positive rate was 0.09%. 100 cases of NPC were found and 87 of them (87.0%) were in early stage. NPC found in the group with single item positive accounts for 1.19%, but the rate in the group with double items positive was 19.16% (55 cases). In NPC patients with double items positive, 49 cases were in early stage (89.1%). In 100 cases of NPC found, 45 cases appeared with negative EA-IgA, only with positive VCA-IgA, which indicated that for diagnosis of NPC, sensitivity of EA-IgA was lower than that of VCA-IgA, but its specificity was higher. Therefore, both can increase the detecting rate and early diagnosis rate of NPC. The age of people checked varied with different antibody positive rate and NPC detecting rate. The three items showed a positive correlation. The results are compatible with those of the prospective study for NPC in Wuzhou City, Guangxi, China. The method for NPC serological diagnosis can be extended and applied to raise the NPC detecting rate and early diagnosis rate at secondary prevention. And, it is further proved that there is a close relationship between NPC and EBV.

Resistance of Neisseria gonorrhoeae to antimicrobial hydrophobic agents is modulated by the mtrRCDE efflux system

The mtr (multiple transferable resistance) system of Neisseria gonorrhoeae determines levels of gonococcal resistance to hydrophobic agents (HAs), including detergent-like fatty acids and bile salts that bathe certain mucosal surfaces. The genetic organization of the mtr system was determined and found to consist of the mtrR gene, which encodes a transcriptional regulator (MtrR), and three tandemly linked genes termed mtrCDE. The mtrCDE genes were organized in the same apparent transcriptional unit, upstream and divergent from the mtrR gene. The mtrCDE-encoded proteins of N. gonorrhoeae were analogous to a family of bacterial efflux/transport proteins, notably the MexABOprK proteins of Pseudomonas aeruginosa and the AcrAE and EnvCD proteins of Escherichia coli, that mediate resistance to drugs, dyes, and detergents. Inactivation of the mtrC gene resulted in loss of the MtrC lipoprotein and rendered gonococci hypersusceptible to structurally diverse HAs; this revealed the importance of the mtr system in determining HAR in gonococci. Further support for a role of the mtrCDE gene complex in determining levels of HAR in gonococci was evident when transformants bearing mutations in the mtrR gene were analysed. In this respect, missense and null mutations in the mtrR gene were found to result in increased levels of MtrC and HAR. However, high levels of MtrC and HAR, similar to those observed for clinical isolates, were associated with a single bp deletion in a 13 bp inverted repeat sequence that intervened the divergent mtrR and mtrC genes. We propose that the 13 bp inverted-repeat sequence represents a transcriptional control element that regulates expression of the mtrRCDE gene complex, thereby modulating levels of gonococcal susceptibility to HAs.

[Genotyping of hepatitis C virus in patients with hepatocellular carcinoma]

Forty-two patients with hepatocellular carcinoma (HCC) were examined for hepatitis C virus (HCV) RNA in liver tissues by reverse transcription-polymerase chain reaction (RT PCR). Typing of HCV liver samples of 18 patients was dependent on the amplification of NS5 region by PCR using type-specific primers. Type-II was found in 14 of the 18 patients (78%), 7 of the 18 patients (39%) and 4 of the 18 patients (22%) were positive for type-II and I and for type-II and III or IV (III/IV), respectively. Type V or VI (V/VI) infection was not observed. These data indicate that HCV type-II may be the major type in HCC patients with HCV infection in China, and some patients can be coinfected with type-II and I or III/IV.

Glucose-6-phosphatase gene expression and activity are modulated in hemorrhagic shock: evidence for a new heat-sensitive activator

Decreased hepatic fructose 2,6-bisphosphate levels were observed in the early phase of hemorrhagic shock. The lower sugar bisphosphatae level was a result of increased phosphoenolpyruvate levels and decreased glucose-6-phosphate and fructose-6-phosphate levels. The decreased glucose-6-phosphate levels correlated with increased activity of liver glucose-6-phosphatase and a concomitant 2.5-fold increase in glucose-6-phosphatase mRNA abundance. In addition, protein-free filtrate from hemorrhagic shock rats, but not from control rats, increased glucose-6-phosphatase activity. However, when control and hemorrhagic shock protein-free filtrates were heated, they both increased the glucose-6-phosphatase activity of the respective microsomes to the same extent. It is concluded that the early hyperglycemic phase of hemorrhagic shock is due to enhanced glucose-6-phosphatase gene expression and activity and the generation of a heat sensitive activator of the enzyme.

The difference in EEG theta waves between concentrative and non-concentrative qigong states--a power spectrum and topographic mapping study

The differences in EEG theta waves between concentrative and non-concentrative Qigong states were studied by means of power spectrum analysis and EEG mapping. The adult subjects included 20 practitioners of concentrative Qigong, 30 practitioners of non-concentrative Qigong and 23 control subjects. The results showed frontal mid-line theta rhythm was related to concentrative Qigong state. As the theta rhythm has been suggested to be one of the normal EEG patterns occurring in mental concentration, it is concluded that the theta rhythm is an indicator of mental concentration during Qigong state. This finding clarifies the implication of the theta rhythms appearing in Qigong and other meditation.

Isolation of a cDNA for the catalytic subunit of rat liver glucose-6-phosphatase: regulation of gene expression in FAO hepatoma cells by insulin, dexamethasone and cAMP

cDNA clones coding for the catalytic subunit of rat liver glucose-6-phosphatase (EC 3.1.3.9) were isolated from a rat liver cDNA library in lambda gt11 phage. The sequence of the cDNA and the amino acid sequence derived from it were greater than 90% identical to the corresponding sequences for the mouse and human forms of liver glucose-6-phosphatase. Northern blot analysis of RNA from FAO hepatoma cells revealed that dexamethasone induced the glucose-6-phosphatase mRNA while insulin suppressed its expression. When both hormones were added together insulin completely suppressed the effect of glucocorticoid. cAMP addition alone decreased the abundance of glucose-6-phosphatase mRNA. The results demonstrate multihormonal regulation of gene expression of hepatic glucose-6-phosphatase and support a dominant role for insulin.

Pandas, people and policy

Panda conservation in China has been plagued by controversy and cultural and political differences. But international cooperation, together with new studies identifying the main threats, offer renewed hope for the species' survival.

Regulation of the permeability of the gonococcal cell envelope by the mtr system

The mtrR gene of Neisseria gonorrhoeae controls the level of susceptibility to hydrophobic antibiotics and detergents. The mtrR gene was cloned and shown to encode a putative transcriptional repressor. The mtr region was homologous to the envCD and acrAB regions of Escherichia coli, which are also involved in susceptibility to hydrophobic compounds. A homologous repressor protein was encoded by a previously unrecognized open reading frame within both the envCD and acrAB regions. Deletion of mtrR resulted in increased resistance to antibiotics and detergents: the mtrR mutations in two penicillin-resistant clinical isolates resulted in a change of His-105 to Tyr. We propose that the mtrR repressor allows gonococci to regulate the permeability of its cell envelope in response to environmental signals, so that they can grow in the presence of toxic faecal lipids in the rectum as well as in the genital tract.