Overexpression of protease-deficient DegP(S210A) rescues the lethal phenotype of Escherichia coli OmpF assembly mutants in a degP background

Replacement of OmpF's conserved carboxy-terminal phenylalanine with dissimilar amino acids severely impaired its assembly into stable trimers. In some instances, interactions of mutant proteins with the outer membrane were also affected, as judged by their hypersensitivity phenotype. Synthesis of all mutant OmpF proteins elevated the expression of periplasmic protease DegP, and synthesis of most of them made its presence obligatory for cell viability. These results showed a critical role for DegP in the event of aberrant outer membrane protein assembly. The lethal phenotype of mutant OmpF proteins in a degP null background was eliminated when a protease-deficient DegP(S210A) protein was overproduced. Our data showed that this rescue from lethality and a subsequent increase in mutant protein levels in the envelope did not lead to the proper assembly of the mutant proteins in the outer membrane. Rather, a detergent-soluble and thermolabile OmpF species resembling monomers accumulated in the mutants, and to a lesser extent in the parental strain, when DegP(S210A) was overproduced. Interestingly, this also led to the localization of a significant amount of mutant polypeptides to the inner membrane, where DegP(S210A) also fractionated. These results suggested that the DegP(S210A)-mediated rescue from toxicity involved preferential sequestration of misfolded OmpF monomers from the normal assembly pathway.

Anti-keratin antibodies in patients with rheumatoid arthritis

As the proportion of patients with rheumatoid arthritis (RA) who have anti-keratin antibodies (AKA) varies in different ethnic groups, we studied its occurrence in a hospital populations with RA and its association with different disease variables. Sera from 84 consecutive patients with RA, 100 healthy controls and 85 disease controls (polyarticular juvenile rheumatoid arthritis, systemic lupus erythematosus, ankylosing spondylitis) were tested for AKA by an indirect immunofluorescence assay that used rat esophagus as substrate. The proportion of patients with RA who had AKA (47/84) was higher than in healthy controls (2/100; P < 0.001) and in disease controls (2/85; P < 0.001). The frequency of AKA positivity was higher among patients who had severe disease (P < 0.05) and rheumatoid factor. Anti-keratin antibody is present in 56 per cent of our patients with RA and is associated with severe disease.

Role of IgM & IgA rheumatoid factors in complement activation in patients with juvenile rheumatoid arthritis

We studied the relationship between the degree of complement activation in juvenile rheumatoid arthritis (JRA) with the levels of circulating IgM and IgA rheumatoid factors (RF). Forty children with JRA and 25 matched controls were included in the study. Levels of C3d (a degradation product of complement component C3), circulating immune complexes (CICs), IgM RF and IgA RF were measured by ELISA. Levels of C3d, CICs, IgM RF and IgA RF were elevated in patients with JRA as compared to controls. Levels of C3d had a linear relationship with levels of CICs (P < 0.05) but not with levels of circulating IgM RF and IgA RF. Thus, complement activation occurs in children with JRA and is associated with raised levels of CICs but not with levels of circulating IgM and IgA RF. Circulating IgM and IgA RF have little, if any, role in complement activation observed in patients with JRA.

Colonic bacteria express an ulcerative colitis pANCA-related protein epitope

Bacteria are a suspected pathogenic factor in inflammatory bowel disease, but the identity of the relevant microbial species remains unresolved. The pANCA autoantibody is associated with most cases of ulcerative colitis (UC) and hence reflects an immune response associated with the disease process. This study addresses the hypothesis that pANCA identifies an antigen(s) expressed by bacteria resident in the human colonic mucosa. Libraries of colonic bacteria were generated using aerobic and anaerobic microbiologic culture conditions, and bacterial pools and clonal isolates were evaluated for cross-reactive antigens by immunoblot analysis using the pANCA monoclonal antibody Fab 5-3. Two major species of proteins immunoreactive to pANCA monoclonal antibodies were detected in bacteria from the anaerobic libraries. Colony isolates of the expressing bacteria were identified as Bacteroides caccae and Escherichia coli. Isolation and partial sequencing of the B. caccae antigen identified a 100-kDa protein without database homologous sequences. The E. coli protein was biochemically and genetically identified as the outer membrane porin OmpC. Enzyme-linked immunosorbent assay with human sera demonstrated elevated immunoglobulin G anti-OmpC in UC patients compared to healthy controls. These findings demonstrate that a pANCA monoclonal antibody detects a recurrent protein epitope expressed by colonic bacteria and implicates colonic bacterial proteins as a target of the disease-associated immune response.

Clinical relevance of IgA rheumatoid factor (RF) in children with juvenile rheumatoid arthritis

This study proposed to investigate the prevalence and clinical relevance of serum immunoglobulin A (IgA) rheumatoid factor (RF) in juvenile rheumatoid arthritis (JRA) as published reports vary in their conclusion. Sera of 82 children with JRA and 25-age and sex-matched healthy children were measured for IgA RF by an enzyme linked immunoassay using human IgG as the antigen. Forty-three percent of the disease population were positive and the prevalence in pauciarticular, polyarticular and systemic onset was 9/18 (50%), 21/47 (44.7%) and 5/17 (27.7%) respectively when mean + 2SD of normal was taken as the cut-off value. By defining the upper limit of normal as mean + 6SD, 16/47 (34%) were positive in the polyarticular as compared to 2/18 (11.1%) in pauciarticular and 1/17 (5.8%) of systemic onset disease groups. The prevalence in the polyarticular subset with the upper cut-off limit was significantly higher than the pauciarticular and the systemic onset group (P < 0.05). Furthermore, the mean level of IgA RF was significantly higher in the polyarticular group compared to the mean level in the systemic onset group (P < 0.05). The mean level of IgA RF was also significantly higher (P < 0.05) in 61 children with active diseases.

Evidence for activation of the alternate complement pathway in patients with juvenile rheumatoid arthritis

OBJECTIVE

Complement activation has been shown to occur in patients with juvenile rheumatoid arthritis (JRA). Since the two pathways of complement are activated by different stimuli (the alternate pathway by microbial products and IgA, and the classical pathway by immune complexes), we decided to study the relative contribution of the two pathways of complement activation in patients with JRA.

METHODS

In 56 patients with JRA, plasma levels of C3 and C4 were measured by turbidimetric assays, and those of C4d, factor Bb and sC5-9 complex by solid-phase enzyme immunoassays. Levels beyond the mean +/- 2 S.D. of normal were considered abnormal.

RESULTS

Plasma C3 and C4 levels were decreased in one patient each. The C4d values were increased in 17 patients, whereas levels of factor Bb were elevated in 42 patients and levels of sC5-9 complex were elevated in 51 patients. The values of factor Bb and sC5-9 had a linear correlation (r = 0.75), but there was no significant correlation between C4d and sC5-9 levels (r = 0.36).

CONCLUSION

Complement activation in JRA is initiated predominantly by the alternate pathway and culminates in the formation of terminal membrane attack complex.

Complement degradation product C3d in urine: marker of lupus nephritis

OBJECTIVE

To examine whether serum and urine C3d, a degradation product of C3, correlate with renal and extrarenal lupus activity.

METHODS

Serum and urinary C3d levels were measured by ELISA in 15 healthy individuals and 24 patients with systemic lupus erythematosus (SLE) (8 with inactive disease, 7 with active but nonrenal disease, 9 with active lupus nephritis). Disease activity variables like serum C3, C4, and anti-dsDNA antibodies were also measured.

RESULTS

The median serum C3d levels were significantly higher (p < 0.01) in patients with active (26 arbitrary units/ml; AU/ml) and inactive SLE (27 AU/ml) compared to healthy controls (11.25 AU/ml); levels were comparable in patients with active renal and extrarenal SLE. On the other hand, urine C3d was elevated only in patients with active SLE; its level was highest in patients with active lupus nephritis (0.87 AU/ml) compared to patients with active extrarenal diseases (0.31 AU/ml; p < 0.05), to patients with inactive lupus nephritis (0.06 AU/ml; p < 0.001), or to levels in healthy individuals (0.06; p < 0.001). Urine C3d showed stronger correlation with disease activity score (SLE Disease Activity Index) than serum C3, C4, anti-dsDNA antibodies, and serum C3d.

CONCLUSION

Urine C3d is a good index of active lupus, particularly lupus nephritis.

Modeling the X-Ray Timing Properties of Cygnus X-1 Caused by Waves Propagating in a Transition Disk

We show that waves propagating in a transition disk can explain the short-term temporal behavior of Cygnus X-1. In the transition-disk model, the spectrum is produced by saturated Comptonization within the inner region of the accretion disk where the temperature varies rapidly with radius. Recently, the spectrum from such a disk has been shown to fit the average broadband spectrum of this source better than that predicted by the soft-photon Comptonization model. Here we consider a simple model in which waves are propagating cylindrically symmetrically in the transition disk with a uniform propagation speed (cp). We show that this model can qualitatively explain (1) the variation of the power spectral density with energy, (2) the hard lags as a function of frequency, and (3) the hard lags as a function of energy for various frequencies. Thus, the transition-disk model can explain the average spectrum and the short-term temporal behavior of Cyg X-1.

Identification of bacteriophage K20 binding regions of OmpF and lipopolysaccharide in Escherichia coli K-12

Two classes of phage K20 resistant Escherichia coli K-12 mutants were obtained. One class of mutants possessed alterations within the ompF gene while the rfa gene cluster, which is responsible for lipopolysaccharide (LPS) synthesis, was affected in the second class of mutants. The OmpF mutants contained substitutions affecting residues localized within the surface-exposed loops 5, 6 or 7. A single deletion mutation resulted in the removal of eight residues of loop 5. These alterations prevented the binding of K20 to cell surface without affecting OmpF's channel activity. One LPS mutant characterized in detail contained an unusual aberration within the rfa gene cluster caused by an IS5 element. Its insertion mediated a deletion encompassing the rfaBIJ genes. Genetic complementation analysis revealed that the rfaB gene, whose product catalyzes the addition of a galactose residue to the first glucose molecule of the LPS core, is necessary to synthesize LPS able to serve as a co-receptor for phage K20.

High-performance liquid chromatographic method for fingerprinting and quantitative determination of E- and Z-guggulsterones in Commiphora mukul resin and its products

A high-performance liquid chromatographic method has been developed and validated for the fingerprinting (profiling) and quantitative determination of E- and Z-guggulsterones, the hypolipidemic agents in the gum-resin exudate of Commiphora mukul, currently marketed worldwide as hypocholesterolemic. The method involves extraction of the guggul-resin from either the raw exudate or compounded tablets (or capsules) with ethyl acetate, concentration of the combined extracts and chromatography on a reversed-phase C18 column using an acetonitrile-water gradient. The method has a validated quantitation range of 15-85 microg/ml for E-guggulsterone and 25-130 microg/ml for Z-guggulsterone with a precision of +/-2% S.D. and a recovery of >99.5%. Standard curve correlation coefficients of 0.992 or greater were obtained during validation experiments. The method was applied to six commercial (OTC) products, all of which were found to contain significantly less (in most cases very little or none) of the claimed guggulsterones.

Modern drug development from traditional medicinal plants using radioligand receptor-binding assays

Traditional medicinal plants in various countries, particularly in India have been used for centuries for various ailments; however, there has been little scientific effort to validate these anecdotal uses mentioned in the literature. A number of these traditionally used plant extracts and various "Ayurvedic medicines" that are highly valued in Ayurveda, the traditional system of medicine in India for antiaging, memory-enhancing, nerve tonic, anxiolytic, anti-inflammatory and immunopotentiation, have been screened using National Institutes of Mental Health (NIMH) Synthetic Screening Program for scientific validation and the development of new leads of psychotherapeutic compounds using Radioligand Receptor Binding Assays (RRA). Crude methanolic extracts of plants are screened using approximately 40 different in vitro RRA (primarily from rat brain homogenates) and 6 enzyme assays including acetylcholine esterase, choline acetyltransferase, and monoamine oxidase (MAO), A and B. The total crude extracts of many of these plants showed potent selectivity to various receptors, especially gamma-Amino Butyric Acid (GABA(A)), N-Methyl-D-Aspartic Acid (NMDA), and MAO receptors, which are presumed to be involved in mental disorders. The focus was on plants showing the highest displacement of GABA, cholecystokinin (CCK), NMDA, MAO, and benzodiazopines. Bioassay guided fractionation of the most active extracts resulted in pure compounds which retained the original activity of the crude extract validating the folkloric use. A bioactivity-guided fractionation of Terminalia bellerica fruit extract led to the isolation of several pure compounds which retained the original activity of the crude extract for CCK and GABA receptors, with the exception of compound B3EA-6, which exhibited high affinity for Neurokinin receptor (Substance K approximately NK-1). The absolute structure of B3EA-6 has been established by x-ray crystallography.

Biochemistry and regulation of a novel Escherichia coli K-12 porin protein, OmpG, which produces unusually large channels

A novel porin, OmpG, is produced in response to a chromosomal mutation termed cog-192. Molecular characterization of cog-192 revealed that it is a large chromosomal deletion extending from the 3' end of pspA through to the 5' end of an open reading frame located immediately upstream of ompG. As a result of this 13.1-kb deletion, the expression of ompG was placed under the control of the pspA promoter. Characterization of OmpG revealed that it is quite different from other porins. Proteoliposome swelling assays showed that OmpG channels were much larger than those of the OmpF and OmpC porins, with an estimated limited diameter of about 2 nm. The channel lacked any obvious solute specificity. The folding model of OmpG suggests that it is the first 16-stranded beta-barrel porin that lacks the large external loop, L3, which constricts the channels of other nonspecific and specific porins. Consistent with the folding model, circular dichroism showed that OmpG contains largely a beta-sheet structure. In contrast to other Escherichia coli porins, there is no evidence that OmpG exists as stable oligomers. Although ompG DNA was present in all E. coli strains examined so far, its expression under laboratory conditions was seen only due to rare chromosomal mutations. Curiously, OmpG was constitutively expressed, albeit at low levels, in Salmonella, Shigella, and Pseudomonas species.

Clinical profile of AIDS: a study at a referral hospital

The present study describes the clinical and epidemiological features of 74 patients with human immunodeficiency virus (HIV) infection who presented to a referral hospital. Sixty two patients (83.7%) were diagnosed to have acquired immune deficiency syndrome (AIDS). Mean age of the patients was 34.9 +/- 12 years and male to female ratio was 3:1. Majority of patients (80%) were from lower socio-economic class. Multiple unprotected heterosexual contact with commercial sex workers in metropolitan cities of India, mainly Mumbai, was major risk factor in 82.1% male patients while most of the females (66.6%) had acquired infection from HIV positive husbands. Blood transfusion was the risk factor in 9(12.1%) patients. Sixty eight patients were infected with HIV 1, one with HIV 2, and five patients with both HIV 1 and HIV 2. Fever and weight loss were the commonest presenting symptoms. Tuberculosis, oropharyngeal candidiasis, and interstitial pneumonitis were present in 54.8%, 40.3% and 20.9% patients, respectively. Fourteen patients (22.5%) had generalised lymphadenopathy. Herpes zoster, cryptococcal meningitis, and peripheral neuropathy were infrequent. Response to standard antifungal and antitubercular treatment was satisfactory. Kaposi's sarcoma, lymphoma, and CNS toxoplasmosis were not found. The clinical manifestations of AIDS patients are strikingly different from that in the Western countries. It, thus, necessitates setting up of different guidelines for the clinical diagnosis and management of AIDS in India.

Significance of elevated IgG anticardiolipin antibody levels in patients with Budd-Chiari syndrome

OBJECTIVES

Budd-Chiari syndrome (BCS) is characterized by hepatic venous outflow obstruction. Though hypercoagulable states are implicated in the causation of BCS, the etiology remains unknown in most cases. Presence of anticardiolipin antibodies (aCL) is a known cause of hypercoagulable state. We therefore studied the frequency of IgG aCL in BCS.

METHODS

Sera were obtained from 19 patients with BCS, 50 healthy controls, 18 age- and gender-matched patients with cirrhosis, and 15 patients with acute viral hepatitis. IgG aCL levels were measured using a solid-phase enzyme immunoassay. Values exceeding mean + 2 SD of healthy controls were taken as abnormal.

RESULTS

Mean +/- SD IgG aCL levels (GPL units) in the four groups were: healthy controls, 6.3 +/- 4.4; BCS, 13.8 +/- 13.3 (p < 0.05, compared with healthy controls); cirrhosis, 15.1 +/- 14.9 (p < 0.05, compared with healthy controls and p = ns, compared with BCS patients); and acute viral hepatitis, 5.0 +/- 2.5 (p = ns, compared with healthy controls). The levels in BCS and cirrhosis patients were similar (p = ns). The number of patients with elevated aCL was: healthy controls, 3/50; BCS, 6/19; cirrhosis, 7/18; and acute viral hepatitis, 0/15. The number of patients with elevated IgG aCL was significantly higher among patients with BCS and cirrhosis, compared with controls (p = 0.03 and p = 0.002, respectively).

CONCLUSIONS

Patients with BCS had higher IgG aCL levels than healthy controls. However, as aCL levels were also elevated in patients with cirrhosis, the pathogenetic role of IgG aCL in the causation of BCS is doubtful.

Antiendothelial cell antibodies in scleroderma correlate with severe digital ischemia and pulmonary arterial hypertension

OBJECTIVE

To determine the prevalence of IgG antiendothelial cell antibodies (AECA) in patients with scleroderma (systemic sclerosis, SSc) and to correlate it with clinical spectrum and autoantibody profile.

METHODS

Seventy-six patients with SSc and 50 matched healthy controls were studied. Immunological variables were antinuclear antibody (ANA), rheumatoid factor (RF), and Scl-70. IgG-AECA was measured by cellular ELISA.

RESULTS

The prevalence of IgG-AECA was 27.6% in patients with SSc compared to 6% in controls (p < 0.01). Forty percent of patients with diffuse disease had this antibody, versus 13.5% of those with limited cutaneous involvement (p < 0.05). Patients with AECA had significantly higher incidence of digital infarcts and gangrene (p < 0.01) and pulmonary arterial hypertension (p < 0.001) than those without. In the AECA positive group, mean IgG-AECA levels (measured by absorbance values) were significantly higher in patients with digital infarcts (0.91+/-0.31 vs 0.60+/-0.05; p < 0.01) and pulmonary arterial hypertension (1.14+/-0.37 vs 0.68+/-0.13; p < 0.001) compared to those without these features.

CONCLUSION

IgG-AECA appears to be an important marker for disease severity in scleroderma.

Modulations in lipid A and phospholipid biosynthesis pathways influence outer membrane protein assembly in Escherichia coli K-12

The assembly defect of a mutant outer membrane protein, OmpF315, can be corrected by suppressor mutations that lower lipopolysaccharide (LPS) levels and indirectly elevate phospholipid levels. One such assembly suppressor mutation, asmB1, is an allele of lpxC (envA) whose product catalyses the first rate-limiting step in the lipid A (LPS) biosynthesis pathway. Besides reducing LPS levels, asmB1 confers sensitivity to MacConkey medium. A mutation, sabA1, that reverses the MacConkey sensitivity phenotype of asmB1 maps within fabZ (whose product is needed for phospholipid synthesis from a precursor) is also required for lipid A synthesis. In addition to reversing MacConkey sensitivity, the sabA1 mutation reverses the OmpF315 assembly suppression phenotype of asmB1. These results show that OmpF315 assembly suppression by asmB1, which is achieved by lowering LPS levels, can be averted by a subsequent aberration in phospholipid synthesis at a point where the biosynthetic pathways for these two lipid molecules split. OmpF315 assembly suppression can also be achieved in an asmB+ background where FabZ expression is increased. The data obtained in this study provide genetic evidence that elevated phospholipid levels and/or phospholipid to LPS ratios are necessary for assembly suppression.

Raised IgM antibodies to parvovirus B19 in juvenile rheumatoid arthritis

To delineate the role of human parvovirus B19 in the etiopathogenesis of juvenile rheumatoid arthritis (JRA), IgM and IgG antibodies specific for parvovirus B19 surface protein antigen(s) were estimated in the sera using commercial ELISA kits. Sera of 69 JRA patients (median age 16 yr, male : female ratio 1.1:1) satisfying the criteria of American Rheumatism Association along with 26 sera of rheumatoid arthritis (RA) and 12 sera of healthy children as disease and normal controls respectively were screened. Of the 69 patients with JRA, 19 (27.5%), 35 (50.7%) and 9 (13%) were positive for IgM, IgG and both IgG and IgM antibodies respectively. Of the 26 disease control sera, 11 (42.3%) were positive for IgG antibodies while none had elevated IgM antibodies. Among 12 healthy controls, 7 (58.3%) were positive for IgG and 1 was positive for both IgG and IgM antibodies. Thus, a statistically significant proportion of children with JRA had evidence of parvovirus B19 infection.

Rupture of uterus in a primigravida prior to onset of labor

Spontaneous rupture of the uterus in a primigravida is very rare. Furthermore, uterine rupture in a primigravida prior to the onset of active labor is extremely uncommon, with very few reported cases. We present a case of antepartum uterine rupture in a 20-year-old primigravida in whom the clinical features resembled those of abruptio placentae.

Is undifferentiated seronegative spondyloarthropathy a forme fruste of reactive arthritis?

Undifferentiated spondyloarthropathy (USpa) may either represent a forme fruste of other spondyloarthropathies like reactive arthritis or be a different disease entity. To study the link between USpa and reactive arthritis, we studied the presence of IgA antibodies to Yersinia enterocolitica, Salmonella typhimurium, Shigella flexneri, Campylobacter jejuni and Chlamydia trachomatis in sera from 14 patients with USpa (European Spondyloarthropathy Study Group criteria) using ELISA. Escherichia coli was used as a control antigen. An OD value of more than the mean +/- 2 S.D. of 51 blood donors was considered positive. Five patients had elevated IgA antibodies to S. flexneri, while two patients each had elevated antibody levels to S. typhimurium and Chlamydia. No patient had elevated antibodies to Y. enterocolitica, C. jejuni and E. coli. Among 51 normals, 1, 4, 3, 2 and 3 had elevated antibodies to S. flexneri, S. typhimurium, Y. enterocolitica, C. jejuni and E. coli, respectively. Nine of 14 patients with USpa had antibodies to one of the bacteria implicated in reactive arthritis: of these, antibodies to Shigella were the most frequent. Thus, a proportion of patients with USpa may in fact have reactive arthritis.

Plant immunomodulators for termination of unwanted pregnancy and for contraception and reproductive health

Neem (Azadirachta indica) seed and leaf extracts have spermicidal, anti-microbial, anti-fungal and anti-viral properties. They are also immunomodulators that induce primarily a TH1 type response. These properties are being exploited to develop two different useful methods of fertility control. Neem extracts given orally at early post-implantation stage terminate pregnancy in rodents and primates. Treatment has no residual permanent effect and fertility is regained in subsequent cycles. The mechanism by which the action occurs is not fully clear. A transient increase in CD4 and more significantly in CD8 cells is noticed in mesenteric lymph nodes and spleen. A rise in immunoreactive and bioactive TNF-alpha and IFN-gamma in draining lymph nodes, serum and foetal-placental tissue is observed. A polyherbal cream and pessary have been developed containing three active ingredients of plant origin. These have synergistic spermicidal properties on human sperm as determined by the Sander Cramer test. Their use before mating has high contraceptive efficacy in rabbits and baboons. Another interesting property is their inhibitory action on a wide spectrum of micro-organisms, including Candida albicans, C. tropicalis, Neisseria gonorrhoeae, the multidrug-resistant Staphylococcus aureus and urinary tract Escherichia coli, Herpes simplex-2 and HIV-1. Phase I clinical trials have been completed in India, Egypt and the Dominican Republic, and indicate the safety of the formulation, its acceptability and beneficial action invaginosis due to infections.