The importance of the helix 2 region for the cis-cleaving and trans-cleaving activities of hepatitis delta virus ribozymes

The sequence, secondary structure, and size requirements of the helix 2 region (H2) of a cis-acting hepatitis delta virus ribozyme Rz 1 were examined in this study. Mutational analysis was performed, and the cleavage rate of each H2 mutant of Rz 1 was assayed. We found that H2 could be elongated to twice its original size without affecting ribozyme folding while the shortening of H2 by one base pair severely decreased autolytic activity. In addition, the maintenance of the Watson-Crick base-pairing interactions of the last base pair of H2 (A16U58) was not critical for cis-cleavage reaction. Nevertheless, mutants with an AA, an AG, an AC, or a GG pair at the bottom of H2 were less active, and the sequence of the H2/H3 interface might affect the stability of the catalytic core. The negative effects on ribozyme folding, such as the destabilization of H2, the unfavorable sequences at the last base pair of H2 as well as the disruption of the continuity of H2 and H3, could be compensated for by elongating the H2 region of the corresponding mutants. The extension of H2 may alter the conformation of ribozyme molecules; in addition, it stabilized the catalytic core and enhanced the resistance to formamide. Finally, for a trans-acting ribozyme and its substrate that require the formation of H1, H2, and H4 to reconstitute the autocatalytic domain of HDV RNA, the extension of H2 stabilized the substrate/ribozyme complex and speeded up the cleavage rate but hindered the product release process.

Probing the Domain Structure of Abrin-a by Tryptic Digestion

Abrin-a is a potent plant toxin that consists of A and B chains linked by a disulfide bond. The abrin-a A chain (AaTA) has N-glycosidase activity while the abrin-a B chain (AaTB) has galactose-binding activity. By partial tryptic digestion, the domain structure of abrin-a was investigated. Seven tryptic fragments with molecular masses greater than 3500 Da were isolated and characterized. One fragment, designated T-21 and consisting of 153 amino acid residues, contained the major part of the second domain of AaTB and, after cross-linking of T-21 with glutaraldehyde, the reaction product had the same level of hemagglutinating activity as native abrin. When the T-21 fragment was conjugated with AaTA, the conjugate inhibited protein biosynthesis in HeLa cells. This suggests that the T-21 fragment is able to bind specifically to cells; its conjugate facilitates membrane translocation of AaTA into cells and consequently inhibits protein biosynthesis. T-21, with a molecular mass less than AaTB, is therefore a potentially useful substance for the preparation of immunotoxins.

Minimally invasive surgery: video endoscopic thoracic sympathectomy for palmar hyperhidrosis

Palmar hyperhidrosis (PH) is a common disorder in Taiwan. It often causes social embarrassment and occupational handicaps. So far, there has been no satisfactory treatment for PH. In 1990, we first developed a minimally invasive technique: video endoscopic sympathectomy to treat PH. The procedure has subsequently proven to be a standard treatment for PH. In this study, a survey of 9988 cases of PH patients from 17 hospitals in Taiwan treated by this method during the past 5 years is presented. Although there were some variations in the model of anaesthesia, technique and extent of sympathectomy, the postoperative results were generally satisfactory. Both sides of sympathectomy were mostly accomplished within half an hour in one stage. The operative scars were tiny and concealed in the axillary region. The patients were discharged from the hospital after an overnight stay. Complications such as pneumothorax, haemothorax (0.3%) or Horner's syndrome (0.1%) were rare. There was no surgical mortality in this series. The most common complication was compensatory hyperhidrosis which was usually mild to moderate and tolerable after reassurance. The recurrence rate of PH was approximately 1% in the first year and less than 3% during the 3 years of follow up. Intraoperative monitoring of palmar skin temperature (PST) was advocated to confirm an adequate sympathectomy warranting a definite result. En bloc ablation of T2 segment invariably resulted in a rise of PST to about 2 degrees C and was considered as an adequate extent of sympathectomy for PH. The refined technique was extended to treat young children with PH and patients with craniofacial hyperhidrosis. The therapeutic results were generally excellent with minimal morbidity and rare recurrence. It is concluded that video endoscopic en bloc T2 sympathectomy is a simple, minimally invasive and effective treatment for both adults and children with PH and also for patients with craniofacial hyperhidrosis.

Prolonged pertussis toxin treatment affects morphine's action on tuberoinfundibular dopaminergic neuron activity and on prolactin secretion

The effects of pertussis toxin (PTX) pretreatment on basal and morphine-affected changes of tuberoinfundibular dopaminergic (TIDA) neuron activity and serum prolactin level were tested in this study. Adult female Sprague-Dawley rats, ovariectomized and treated with a long-acting estrogen (polyestradiol phosphate, 0.1 mg/rat, s.c.), were used. The activity of TIDA neurons was determined by measuring the turnover rate of dopamine (DA), and the concentrations of 3,4-dihydroxyphenylacetic acid (DOPAC) or 3,4-dihydroxyphenylalanine (DOPA) in the median eminence. Acute (30-90 min) treatment of PTX had no significant effect on any of the parameters measured. Prolonged (24 h) treatment of PTX significantly reduced morphine's inhibitory effect on TIDA neuron activity (using DOPA, but not DOPAC as the index), and stimulatory effect on PRL release. Basal TIDA neuron activity as determined by median eminence DOPAC concentration, DOPA accumulation, or DA rate constant was not significantly altered by PTX. Median eminence DA level, however, was significantly reduced. These results suggest that a pertussis toxin-sensitive GTP-binding protein may be responsible for the maintenance of TIDA neurons, and for mediation of the inhibitory effect of morphine on TIDA neuron activity, and in turn, the stimulation of prolactin secretion.

Epicutaneous exposure of protein antigen induces a predominant Th2-like response with high IgE production in mice

Hapten-induced contact hypersensitivity has been well-characterized in humans as well as in animal models. However, it is not clear whether or not protein Ag can directly sensitize epicutaneously and induce a primary immune response. We demonstrated in this study, for the first time, that through epicutaneous exposure protein Ag in the absence of adjuvant sensitizes animals and induces a predominant Th2-like response. Furthermore, mice receiving repeated protein Ag sustained elevated levels of specific IgE. This animal model can be used to investigate the molecular mechanism controlling the differential Th1/Th2 development in skin diseases.

Epicutaneous exposure of protein antigen induces a predominant Th2-like response with high IgE production in mice

Hapten-induced contact hypersensitivity has been well-characterized in humans as well as in animal models. However, it is not clear whether or not protein Ag can directly sensitize epicutaneously and induce a primary immune response. We demonstrated in this study, for the first time, that through epicutaneous exposure protein Ag in the absence of adjuvant sensitizes animals and induces a predominant Th2-like response. Furthermore, mice receiving repeated protein Ag sustained elevated levels of specific IgE. This animal model can be used to investigate the molecular mechanism controlling the differential Th1/Th2 development in skin diseases.

The association between lung innate immunity and differential airway antigen-specific immune responses

The mechanisms involved in the differential regulation of airway immune responses in atopic versus non-atopic individuals are poorly understood. In this study, the association between non-specific immunity and the differential airway antigen-specific immune responses was examined in a murine model. The disparity in antigen-specific IgE and IgG2a productions between the two strains of mice was observed to be significant. C57BL/6J mice were much more efficient than BALB/cJ mice in making IgE antibody to inhaled ovalbumin (OVA) antigen. On the contrary, BALB/cJ mice did make more IgG2a antibodies than C57BL/6J mice to inhaled OVA. These findings suggest that in C57BL/6J mouse strain a predominant Th2 type of immune response develops in response to inhaled OVA antigen. In contrast, BALB/cJ mice mount a Th1 type of immune response to aerosolized OVA antigen. Furthermore, after lipopolysaccharide (LPS) stimulation, the IL-12 mRNA expression of lung-derived cells from BALB/cJ mice was higher than that from C57BL/6J cells. However, the lung-derived cells of C57BL/6J mice stimulated by LPS produced higher levels of IL-10 and prostaglandin E2 than BALB/cJ lung-derived cells did. Therefore, our study demonstrated that the difference of lung-derived cells in their ability to produce cytokine and prostaglandin between BALB/cJ and C57BL/6J mice correlates well with the type of the airway antigen-specific immune effector functions.

Effects of circular permutation on the cis-cleavage reaction of a hepatitis delta virus ribozyme: application to trans-acting ribozyme design

In this study we investigated the effects of the relocation of the wild type termini on the folding of a cis-cleaving RNA Rz 1 that was modified from the autolytic domains of hepatitis delta virus (HDV) RNA. Ten circularly permuted (CP) isomers of this ribozyme were synthesized. The structure homogeneity of RNA molecules, the molar ratio of the active species that undergoes cis-cleavage, and the rate of cis-cleavage were examined for each construct. CP isomers with new termini in H1 or at the junction of H2-H3, H1-J1/4, J1/4-H4, or H4-J4/2 of the proposed pseudoknot-like structure were inactive. The single breaks of phosphodiester bond in H2, J1/2, Lp4, and at the 3'-end of Lp3 decreased but did not abolish autolytic activity. The structural heterogeneity of RNA molecules may account for the limited cis-cleavage of the latter three isomers. The findings of circular permutation analysis were used as the basis for designing an active trans-cleaving ribozyme by dividing the cis-cleaving ribozyme into two subdomains at J1/2 and Lp4. The ribozyme subdomain catalyzed the site-specific cleavage of the circularly permuted composite substrate RNA in trans. Thus, the structure of HDV autolytic domain could be re-formed after two subdomains were associated through the base-pairing interactions of H1, H2, and H4.

Crystallization and preliminary x-ray analysis of volvatoxin A2 from Volvariella volvacea

Volvatoxin A2, an ion channel disturbed cardiotoxic and hemolytic protein from the edible mushroom, Volvarilla volvacea, has been crystallized by the vapor diffusion method using polyethylene glycol 4000 and ammonium sulfate in sodium acetate buffer pH 4.6. The best crystals belong to the monoclinic space group C2 with unit cell dimensions a = 155.25 angstroms, b = 58.06 angstroms, c = 116.92 angstroms, and beta = 119.5 degrees. These crystals diffract to at least 2.2 angstroms and there are four molecules of molecular weight 24 kDa per asymmetric unit with a solvent content of 48%.

Home care for the urban chronically ill elderly in the People's Republic of China

This study examines the home care situation of seventy-five urban chronically ill men and women and their caregivers in three cities in the People's Republic of China. It documents the type of home care provided, the severity of illness, and the dependency in activities of daily living in order to appreciate the complexity of these care situations. The findings reveal that women serve as the caregivers in the majority of the cases and often they are elderly spouses with health problems of their own. The physical, social, psychological, and financial problems experienced by these patients create an enormous burden for the caregivers whether spouses or younger family members coming home from work to a second shift. If alternatives to home care, such as nursing homes, were available, 54 percent of these caregivers would be willing to institutionalize their elderly relative. All caregivers express the need for more assistance in providing home care. This study raises questions regarding the role of the family, the state, and specifically the health care system in caring for the elderly chronically ill in light of their increasing numbers in the population.

Growth suppression of human colorectal carcinoma in nude mice by monoclonal antibody C27-abrin A chain conjugate

PURPOSE

The aim of this study was to assess an immunotoxin, monoclonal antibody C27-abrin A chain conjugate (MAAAC), that might be effective in the treatment of colorectal carcinoma.

METHODS

The immunotoxin was prepared by a specific monoclonal antibody against carcinoembryonic antigen (CEA), monoclonal antibody C27, linked to N-succinimidyl-3-(2-pyridyldithio)propionate and then coupled covalently to the toxic abrin-A chain to synthesize MAAC. The therapeutic role of this immunotoxin in suppressing the in vitro and in vivo growth of CEA-secreting human colorectal cancer cells (LS174T) was assayed by methods of protein biosynthesis inhibition, cell colony proliferation, and treatment of tumor cells before and after inoculation in nude mice.

RESULTS

We found that MAAC effectively suppressed the growth of LS174T in culture medium and completely eradicated cells in inoculated nude mice. In contrast, irrelevant immunotoxin antiferritin-abrin A chain conjugate and isotype-matched monoclonal immunoglobin (MOPC21IgG1)-abrin A chain conjugate did not cause such effects. The in vitro toxicity was highly specific because the conjugate (MAAC) inhibited de novo protein biosynthesis, impeded growth, and caused death of cells possessing surface CEA determinants. The 50 percent inhibition dose values of the conjugate for colonogenic survival and for protein biosynthesis in LS174T cells were 0.09 microgram/ml and 0.06 microgram/ml, respectively. Colon survival was inhibited 96.3 percent after prolonged MAAC treatment. MAAC showed selective cytotoxicity; the inhibitory effect of MAAC to the CEA-secreting LS174T cells over the CEA-nonsecreting human embryonic kidney cells was 16-fold.

CONCLUSION

These results indicate that MAAC may be of benefit in therapy during or soon after resection of colorectal carcinoma or in patients who have micrometastasis.

Native and/or asialo-Tamm-Horsfall glycoproteins Sd(a+) are important receptors for Triticum vulgaris (wheat germ) agglutinin and for three toxic lectins (abrin-a, ricin and mistletoe toxic lectin-I)

The binding properties of human Tamm-Horsfall Sd(a+) urinary glycoprotein (THGP) and asialo-THGP with Triticum vulgaris agglutinin(WGA) and three toxic lectins (abrin-a, ricin, and Mistletoe toxic lectin-I) were investigated by quantitative precipitin and precipitin inhibition assays. Both glycoproteins reacted strongly with abrin-a, precipitating over 80% of the lectin nitrogen tested. THGP also bound well to mistletoe toxic lectin-I and precipitated 86% of this lectin added, while the precipitability of its asialo product decreased by 28%. The native glycoprotein completely precipitated the WGA added, but its reactivity was reduced dramatically after desialylation. On the contrary, the poor reactivity of THGP with ricin increased substantially after removal of sialic acid and completely precipitated the lectin added. The glycoprotein-lectin interactions were inhibited by one or several of the following haptens, p-NO2-phenyl alpha GalNAc, p-NO2-phenyl beta GalNAc, Gal beta 1-->4GlcNAc, Gal beta 1-->4Glc, GlcNac beta 1-->4GlcNAc and/or GlcNAc. From the above results, it is concluded that native and/or Tamm-Horsfall glycoproteins serve as important receptors for these three toxic lectins and for WGA.

Differential inhibition of reverse transcriptase and cellular DNA polymerase-alpha activities by lignans isolated from Chinese herbs, Phyllanthus myrtifolius Moon, and tannins from Lonicera japonica Thunb and Castanopsis hystrix

Two lignans, phyllamycin B and retrojusticidin B isolated from Phyllanthus myrtifolius Moon have been demonstrated to have a strong inhibitory effect on human immunodeficiency virus-1 reverse transcriptase activity (HIV-1 RT), but much less inhibitory effect on human DNA polymerase-alpha (HDNAP-alpha) activity. Fifty percent inhibitory concentrations of phyllamycin B and retrojusticidin B were determined to be 3.5 and 5.5 microM for HIV-1 RT, and 289 and 989 microM for HDNAP-alpha, respectively. The mode of inhibition was found to be non-competitive inhibition with respect to template-primer and triphosphate substrate. Several tannins such as caffeoylquinates (CQs) isolated from Lonicera japonica Thunb, galloylquinates (GQs) and galloylshikimates (GSs) purified from Castanopsis hystrix were shown to have a much less selective inhibitory effect on HIV-1 RT.

Crystal structure of abrin-a at 2.14 A

The crystal structure of abrin-a, a type II ribosome-inactivating protein from the seeds of Abrus precatorius, has been determined from a novel crystalline form by the molecular replacement method using the coordinates of ricin. The structure has been refined at 2.14 A to a R-factor of 18.9%. The root-mean-square deviations of bond lengths and angles from the standard values are 0.013 A and 1.82 degrees, respectively. The overall protein folding is similar to that of ricin, but there are differences in the secondary structure, mostly of the A-chain. Several parts of the molecular surface differ significantly; some of them are quite near the active site cleft, and probably influence ribosome recognition. The positions of invariant active site residues remain the same, except the position of Tyr74. Two water molecules of hydrogen-bonded active site residues have been located in the active site cleft. Both of them may be responsible for hydrolyzing the N-C glycosidic bond. The current abrin-a structure is lactose free; this is probably essential for abrin-a crystallization. The B-chain is a glycoprotein, and the positions of several sugar residues of two sugar chains linked to earlier predicted glycosylation sites were determined. One of the sugar chains is a bridge between two neighboring molecules, since one of its mannose residues is connected to the galactose binding site of the neighboring molecule. Another sugar chain covers the surface of the B-chain.

Transforming growth factor-beta 1 primes macrophages for enhanced expression of the nitric oxide synthase gene for nitric oxide-dependent cytotoxicity against Entamoeba histolytica

Nitric oxide (NO) produced by activated macrophages is the major cytotoxic molecule for in vitro cytotoxicity against Entamoeba histolytica trophozoites. Transforming growth factor-beta 1 (TGF-beta 1) is a potent negative regulator of several macrophage functions, including NO production. In this study, we investigated the effect of TGF-beta 1 on macrophage nitric oxide synthase (mac-NOS) mRNA expression and NO production for macrophage cytotoxicity against E. histolytica trophozoites. TGF-beta 1 by itself was incapable of inducing mouse bone marrow-derived macrophage (BMM) amoebicidal activity and NO production (as measured by nitrite). In contrast, TGF-beta 1 pretreatment (4 hr) primed BMM for an enhanced amoebicidal activity of 15% and 23% in response to (interferon-gamma) IFN-gamma+tumour necrosis factor-alpha (TNF-alpha) or IFN-gamma+lipopolysaccharide LPS, concomitant with increased NO production of 85% and 27%, respectively. TGF-beta 1 pretreatment increased NO production in response to IFN-gamma+TNF-alpha/LPS stimulation in a time- and dose-dependent manner. By Northern blot analysis, the increased NO production of TGF-beta 1-pretreated BMM was preceded by markedly enhanced expression of mac-NOS mRNA. The priming effect of TGF-beta 1 on NO production was critically dependent on both a TNF-alpha (> or = 100 U) and a LPS (> or = 100 ng) triggering dose in the presence of IFN-gamma. TGF-beta 1 pretreatment enhanced TNF-alpha mRNA expression, but had no effect on TNF-alpha production in culture supernatants after 4 hr of stimulation with IFN-gamma+TNF-alpha/LPS; however, at a later time-point (16-48 hr), even though the levels of TNF-alpha mRNA expression were unaffected, TNF-alpha production was reduced. These data demonstrate that TGF-beta 1 priming for increased mac-NOS mRNA expression for NO-dependent cytotoxicity against E. histolytica in response to IFN-gamma+TNF-alpha/LPS stimulation may be involved in the modulation of a TNF-alpha triggering signal by TGF-beta 1.

Amino acid sequences of trypsin inhibitors from the melon Cucumis melo

Two squash family trypsin inhibitors, CMeTI-A and CMeTI-B, were isolated from the melon (Cucumis melo) seeds, by ion exchange chromatography, gel filtration, affinity chromatography, and high-performance liquid chromatography, and their amino acid sequences were determined. All inhibitors contain 29 amino acid residues including 6 half-cystine residues. They differ by twelve amino acid residues. These polypeptides are strong inhibitors of bovine trypsin, with Ki values of 1.6 x 10(-10) M (CMeTI-A) and 4.7 x 10(-10) M (CMeTI-B). The products of CMeTI-A and CMeTI-B cleaved at their reactive sites by tryptic digestion during the purification by trypsin-Sepharose 4B affinity column chromatography are active against trypsin activity, but a molar ratio of inhibitor to trypsin of 2:1 for trypsin-treated CMeTI-B or 1:1 for trypsin-treated CMeTI-A is required.

A new fungal immunomodulatory protein, FIP-fve isolated from the edible mushroom, Flammulina velutipes and its complete amino acid sequence

A new fungal immunomodulatory protein (FIP-fve) has been isolated and purified from the edible golden needle mushroom (Flammulina velutipes). The apparent molecular mass of FIP-fve determined by SDS/PAGE agrees well with the value of 12704 Da calculated from its amino acid composition and sequence. The complete amino acid sequence of FIP-fve was elucidated by protein sequencing techniques. FIP-fve consists of 114 amino acid residues with an acetylated amino end, and lacks methionine, half-cystine and histidine residues. FIP-fve was able to hemagglutinate human red blood cells. The immunomodulatory activity of FIP-fve was demonstrated by its stimulatory activity toward human peripheral blood lymphocytes, and its suppression of systemic anaphylaxis reactions and local swelling of mouse footpads. FIP-fve was found to enhance the transcriptional expression of interleukin-2 and interferon-gamma.

A sheep hydatid cyst glycoprotein as receptors for three toxic lectins, as well as Abrus precatorius and Ricinus communis agglutinins

The binding properties of a glycoprotein with blood group P1 specificity isolated from sheep hydatid cyst fluid with Gal and GalNAc specific lectins was investigated by quantitative precipitin and precipitin inhibition assays. The glycoprotein completely precipitated Ricinus communis agglutinin (RCA1), Abrus precatorius agglutinin (APA) and Mistletoe toxic lectin-I (ML-I). Only 1.0 microgram of P1 glycoprotein was required to precipitate 50% of 5.1 micrograms ML-I nitrogen. It also reacted well with abrin-a and ricin, precipitating over 73% of the lectin nitrogen added, but poorly or weakly with Dolichos biflorus (DBL), Vicia villosa (VVL, a mixture of A4, A2B2 and B4), VVL-B4, Arachis hypogaea (PNA), Maclura pomifera (MPL), Bauchinia purpurea alba (BPL) and Wistaria floribunda (WFL) lectins. When an inhibition assay in the range of 5.1 micrograms N to 5.9 micrograms N of lectins (ML-I, abrin-a; ricin, RCA1, and APA, and 10 micrograms P1 active glycoprotein interaction was performed; from 76 to 100% of the precipitations were inhibited by 0.44 and 0.52 mumol of Gal alpha 1-->4Gal and Gal beta 1-->4GlcNAc, respectively, but not or insignificantly with 1.72 mumol of GlcNAc. The Gal alpha 1-->4Gal disaccharide found in this P1 active glycoprotein is a frequently occurring sequence of many glycosphingolipids located at the surface of mammalian cell membranes, especially human erythrocytes and intestinal cells for ligand binding and microbial toxin attachment. The present finding suggests that the Gal alpha 1-->4Gal beta 1-->4GlcNAc sequence in this P1 active glycoprotein is one of the best glycoprotein receptors for three toxic lectins (ricin, abrin-a, and ML-I) as well as for APA, and RCA1, and the result of inhibition assay implies that these lectins are recognizing part or all of the Gal alpha 1-->4Gal beta 1-->4GlcNAc sequence in the P1 active glycoprotein.

TNF-alpha expression by resident microglia and infiltrating leukocytes in the central nervous system of mice with experimental allergic encephalomyelitis. Regulation by Th1 cytokines

The inflammatory cytokines IFN-gamma and TNF-alpha have been demonstrated in various autoimmune diseases, and are thought to participate in the induction and pathogenesis of disease. TFN-alpha is a cytopathic cytokine that is cytotoxic for oligodendrocytes in vitro and has been implicated in the pathology of multiple sclerosis and its animal model experimental allergic encephalomyelitis (EAE). We used reverse transcriptase (RT)-PCR to study the kinetics, cellular source, and regulation of cytokine gene expression in the central nervous system (CNS) of SJL/J mice with myelin basic protein-induced EAE at different stages of the disease. The expression of CD3, IL-2, IFN-gamma, and TNF-alpha mRNA was barely detectable in the CNS of unmanipulated mice or mice that were immunized with adjuvant but showed no symptoms. These mRNAs were readily detectable in the CNS of mice during peak disease, then coordinately dropped to background levels during remission. Analysis of cells isolated from the CNS of mice with acute EAE showed that the Th1 cytokines, IL-2 and IFN-gamma, were produced by infiltrating CD4+ T cells. In contrast, TNF-alpha was predominantly transcribed by non-T mononuclear CNS cells, the majority of which were identified as microglia and macrophages by their Mac-1 phenotype. Microglia could be discriminated by their low expression of CD45. Incubation of freshly derived, adult microglia from normal, uninfiltrated, CNS with activated Th1 supernatant induced the production of TNF-alpha mRNA. Therefore, TNF-alpha is made by both CNS-resident microglia and infiltrating macrophages during EAE, and this production is tightly controlled by cytokines secreted by infiltrating CD4+ T cells.

TNF-alpha expression by resident microglia and infiltrating leukocytes in the central nervous system of mice with experimental allergic encephalomyelitis. Regulation by Th1 cytokines

The inflammatory cytokines IFN-gamma and TNF-alpha have been demonstrated in various autoimmune diseases, and are thought to participate in the induction and pathogenesis of disease. TFN-alpha is a cytopathic cytokine that is cytotoxic for oligodendrocytes in vitro and has been implicated in the pathology of multiple sclerosis and its animal model experimental allergic encephalomyelitis (EAE). We used reverse transcriptase (RT)-PCR to study the kinetics, cellular source, and regulation of cytokine gene expression in the central nervous system (CNS) of SJL/J mice with myelin basic protein-induced EAE at different stages of the disease. The expression of CD3, IL-2, IFN-gamma, and TNF-alpha mRNA was barely detectable in the CNS of unmanipulated mice or mice that were immunized with adjuvant but showed no symptoms. These mRNAs were readily detectable in the CNS of mice during peak disease, then coordinately dropped to background levels during remission. Analysis of cells isolated from the CNS of mice with acute EAE showed that the Th1 cytokines, IL-2 and IFN-gamma, were produced by infiltrating CD4+ T cells. In contrast, TNF-alpha was predominantly transcribed by non-T mononuclear CNS cells, the majority of which were identified as microglia and macrophages by their Mac-1 phenotype. Microglia could be discriminated by their low expression of CD45. Incubation of freshly derived, adult microglia from normal, uninfiltrated, CNS with activated Th1 supernatant induced the production of TNF-alpha mRNA. Therefore, TNF-alpha is made by both CNS-resident microglia and infiltrating macrophages during EAE, and this production is tightly controlled by cytokines secreted by infiltrating CD4+ T cells.

Use of the urine-to-blood carbon dioxide tension gradient as a measurement of impaired distal tubular hydrogen ion secretion among neonates

To evaluate the utility of the urinary-minus-blood partial pressure of carbon dioxide (U-B PCO2) gradient for the diagnosis of distal renal tubular acidosis in neonates, we measured the U-B PCO2 gradient corresponding to different urinary bicarbonate concentrations in 40 neonates. The U-B PCO2 gradient in these neonates had a significant linear relationship to the urinary bicarbonate concentration. When the urinary bicarbonate concentration was > 10 mmol/L, in all the neonates the U-B PCO2 could be increased above the 20 mm Hg level. We conclude that it is appropriate to determine the U-B PCO2 gradient as an index of distal urinary acidification and that it is a necessary test for diagnosis of distal renal tubular acidosis in neonates.