Acute Pancreatitis: A Rare Post-Colonoscopy Sequela

Abdominal pain is a common but benign symptom after colonoscopy. We report a case of acute pancreatitis that occurred just after an elective screening colonoscopy; this is a rare event with very few reported cases. A healthy, asymptomatic male underwent screening colonoscopy at our center and developed abdominal pain and emesis after the procedure. An abdominal X-ray ruled out perforation but laboratory tests revealed elevated levels of amylase and lipase. The patient had no etiological risk factors for pancreatitis. The presumed mechanism of pancreatitis in this case is mechanical and pressure trauma from excessive insufflation, external abdominal pressure, and repeated withdrawal of the colonoscope due to tight angulation of the splenic flexure, a structure that is in close proximity to the pancreatic tail. Acute pancreatitis should be considered in the differential diagnosis of patients who present with abdominal pain after colonoscopy once more common etiologies have been excluded.

Histoid Leprosy Presenting with Keloid Like Lesions

A 42 year old male presented with multiple, discrete, hyperpigmented, firm, non elastic, non tender papules and plaques on the posterior trunk of 5 months duration, resembling keloid. The patient had also a few skin colored papules on the anterior trunk and face. The sensations over the skin lesions were intact. The patient had glove and stocking type of anesthesia and bilaterally thickened, non tender peripheral nerve trunks. The slit skin smear for acid fast bacilli from the ear lobes, skin lesions and normal skin were highly positive for Mycobacterium leprae. A skin biopsy showed a well defined collection of spindle shaped histiocytes in the dermis packed with acid fast bacilli. We are presenting here a case of histoid leprosy presenting with keloid like lesions, probably the rarest presentation of histoid leprosy.

A robust spike and wave algorithm for detecting seizures in a genetic absence seizure model

Animal Models are used extensively in basic epilepsy research. In many studies, there is a need to accurately score and quantify all epileptic spike and wave discharges (SWDs) as captured by electroencephalographic (EEG) recordings. Manual scoring of long term EEG recordings is a time-consuming and tedious task that requires inordinate amount of time of laboratory personnel and an experienced electroencephalographer. In this paper, we adapt a SWD detection algorithm, originally proposed by the authors for absence (petit mal) seizure detection in humans, to detect SWDs appearing in EEG recordings of Fischer 334 rats. The algorithm is robust with respect to the threshold parameters. Results are compared to manual scoring and the effect of different threshold parameters is discussed.

Quantum dots as enhancers of the efficacy of bacterial lethal photosensitization

Because of the increasing resistance of bacteria to antibiotics there is considerable interest in light-activated antimicrobial agents (LAAAs) as alternatives to antibiotics for treating localized infections. The purpose of this study was to determine whether CdSe/ZnS quantum dots (QD) could enhance the antibacterial activity of the LAAA, toluidine blue O (TBO). Suspensions of Staphylococcus aureus and Streptococcus pyogenes were exposed to white light (3600 lux) and TBO (absorbance maximum = 630 nm) in the presence and absence of 25 nm diameter QD (emission maximum = 627 nm). When the TBO:QD ratio was 2667:1, killing of Staph. aureus was enhanced by 1.72log(10) units. In the case of Strep. pyogenes, an enhanced kill of 1.55log(10) units was achieved using TBO and QD in the ratio 267:1. Singlet oxygen and fluorescence measurements showed that QD suppress the formation of singlet oxygen from TBO and that QD fluorescence is significantly quenched in the presence of TBO (70-90%). Enhanced killing appears to be attributable to a non-Förster resonance energy transfer mechanism, whereby the QD converts part of the incident light to the absorption maximum for TBO; hence more light energy is harvested, resulting in increased concentrations of bactericidal radicals. QD may, therefore, be useful in improving the efficacy of antimicrobial photodynamic therapy.

The interaction between staphylococcal superantigen-like proteins and human dendritic cells

Staphylococcus aureus produce a family of exotoxins (staphylococcal superantigen like proteins, SSLs) with structural, but not functional, homology to superantigens. These proteins have previously been shown to interact selectively with antigen presenting cells, including dendritic cells. The functional consequences of this interaction are now explored. SSL7 and 9 had no effect on viability or morphology of dendritic cells. The proteins did not induce dendritic cell maturation, as measured by cell surface phenotype. Exposure to SSL did not alter the ability of dendritic cells to take up FITC-dextran. Finally, exposure to SSLs did not impair the ability of the dendritic cells to stimulate allogeneic or antigen specific T cell responses. However, dendritic cells loaded with SSL7 or 9 were able to stimulate a T cell proliferative response in 3/8 healthy individuals tested. Sera from nine out of 10 individuals tested contained antibodies against both SSL7 and SSL9, and the response to each SSL was specific and not cross-reactive. The results demonstrate that SSLs are immunogenic in humans at both the B and T cell level, but it remains unclear whether this response is to the benefit of the bacterium or the host.

Protective immune response against foot-and-mouth disease virus challenge in guinea pigs vaccinated with recombinant P1 polyprotein expressed in Pichia pastoris

Vaccination of the susceptible livestock with potent, safe and cost effective vaccine is the primary requirement to control foot-and-mouth disease (FMD) in an endemic country. In this study, an alternative approach was used in which structural protein genes of all the four serotypes of FMDV (O, Asia 1, A22 and C) were expressed separately in methylotrophic yeast Pichia pastoris. The recombinant polyproteins (P1) were characterized by SDS-PAGE and in Western Blot analysis. Partially purified protein was used for immunization in guinea pigs with different adjuvant formulations and immune response studied. Ninety micrograms of the recombinant protein per monovalent dose was used for immunization. A single injection of a monovalent or polyvalent vaccine was given to guinea pigs with various adjuvant combinations viz., Monovalent recombinant protein either adjuvanted with Montanide-ISA50V or Indigenous oil, Monovalent recombinant protein mixed with 1/10th dose of inactivated oil-adjuvanted virus vaccine and Polyvalent recombinant protein with Montanide ISA50V. FMDV specific humoral immune response was observed at about 28th day post vaccination. The immune response as assessed by indirect ELISA and Serum neutralization test titres was found to be 320-640 and 16-32, respectively. When challenged with virulent homologous type 'O' virus, the guinea pigs showed protective C index of 2.01,1.81, 2.56 and 2.48, respectively, with above said adjuvant combinations. The study has shown that yeast-expressed FMDV P1 polyprotein in a single dose could elicit a protective immune response in guinea pigs, and this could be a possible future vaccine candidate in homologous host.

Clinico-epidemiological study of HIV patients in Trivandrum

A retrospective descriptive study of 121 HIV patients in the Department was carried out. The male/female ratio was 2.3:1. The maximum number of patients were seen in age group 21-40 (77.68%). Skilled workers constituted the maximum (13.2%). Sexual route was the commonest mode of transmission (78.5%). Cutaneous manifestations were present in 57% of patients, oral condidiasis being the commonest (16.5%). Pulmonary tuberculosis was the commonest systemic manifestation (13.2%). 37 patients (30.57%) had other STD's, syphilis being the commonest (12.39%). 22 patients had AIDS defining conditions.

Early antibody responses of cattle for foot-and-mouth disease quadrivalent double oil emulsion vaccine

Foot-and-mouth disease (FMD) is an economically important disease of cloven-hoofed animals. The multiplicity of FMDV serotypes in animals poses a central problem in the policy of vaccination and is of much concern to health authorities. Hence it is the practice of vaccination with polyvalent vaccine for prophylactic measure. In the present report, we analysed the early antibody responses elicited by FMDV quadrivalent (FMDV O, A, C and Asia 1 serotypes) double emulsion (Montanide ISA 206) vaccines in cattle. We observed variations between various viral serotypes in eliciting early antibody response although neutralizing antibody response against all the four serotypes were detected as early as fourth day following vaccination. The duration of immunity also appeared to maintain for long period. The neutralizing antibody titres were maintained well above 2log(10) even after 6 months of vaccination irrespective of serotypes. Thus, allows the possibilities of two vaccinations per year for the maintenance of herd immunity.

Expression of the S. aureus hysA gene in S. carnosus from a modified E. coli-staphylococcal shuttle vector

We have modified an E. coli-staphylococcal shuttle vector for use in the general cloning and expression of genes from pathogenic staphylococci in Staphylococcus carnosus. As S. carnosus is non-pathogenic, this expression system will facilitate the study of the roles of individual gene products in the disease process. To evaluate the use of this expression system, a DNA fragment containing the Staphylococcus aureus hyaluronate lyase (hysA) gene was cloned into the modified vector, pNW21, and introduced into S. carnosus. Hyaluronate lyase was both produced and secreted by S. carnosus. In addition, the secreted HysA protein was enzymatically active, as determined using a zymographic assay.

Staphylococcus aureus fibronectin binding proteins A and B possess a second fibronectin binding region that may have biological relevance to bone tissues

Staphylococcus aureus is a major human pathogen that has a propensity for targeting to bone tissues and thereby causing bone disease. A plausible hypothesis is that S. aureus targets to bone using the MSCRAMM family of surface proteins possessed by this organism. Two such proteins that have recently been shown to be important in bone infections are the S. aureus fibronectin binding proteins (FnBP) A and B. To identify fibronectin-binding domains from S. aureus that have biological relevance to bone, a phage display library of S. aureus genomic DNA was constructed and panned sequentially against immobilized fibronectin and cultured osteoblasts. Using this system, phage displaying a second fibronectin-binding region within the N-terminal part of FnBPA and FnBPB, which is distinct from the primary fibronectin-binding domain located within the D repeat region of these proteins, was isolated. Phage displaying this second region bound to both immobilized fibronectin and to osteoblasts and/or the extracellular matrix synthesized by these cells, thereby suggesting a biological relevance for these regions in S. aureus binding to bone tissues. Analysis of these binding regions for their ability to bind to other extracellular matrix proteins revealed a preference for fibronectin, with slight binding to fibrinogen and no binding to collagen or laminin.

Recombinant Actinobacillus actinomycetemcomitans cytolethal distending toxin proteins are required to interact to inhibit human cell cycle progression and to stimulate human leukocyte cytokine synthesis

It has recently been discovered that Actinobacillus actinomycetemcomitans, an oral bacterium causing periodontitis, produces cytolethal distending toxin (CDT), a cell cycle-modulating toxin that has three protein subunits: CdtA, CdtB, and CdtC. In this study, we have cloned and expressed each toxin gene from A. actinomycetemcomitans in Escherichia coli and purified the recombinant Cdt proteins to homogeneity. Individual Cdt proteins failed to induce cell cycle arrest of the human epithelial cell line HEp-2. The only combinations of toxin proteins causing cell cycle arrest were the presence of all three Cdt proteins and the combination of CdtB and CdtC. A similar experimental protocol was used to determine if recombinant Cdt proteins were able to induce human peripheral blood mononuclear cells (PBMCs) to produce cytokines. The individual Cdt proteins were able to induce the synthesis by PBMCs of interleukin-1beta (IL-1beta), IL-6, and IL-8 but not of tumor necrosis factor alpha, IL-12, or granulocyte-macrophage colony-stimulating factor, with CdtC being the most potent and CdtB being the least potent cytokine inducer. There was evidence of synergism between these Cdt proteins in the stimulation of cytokine production, most markedly with gamma interferon, which required the minimum interaction of CdtB and -C to stimulate production.

Identification of photolabile outer membrane proteins of Porphyromonas gingivalis

As the prevalence of antibiotic-resistant strains of bacteria increases, novel ways of treating infections need to be developed. This is particularly pertinent with respect to the periodontal diseases--the most common chronic bacterial infections of man. The use of a photosensitizer in combination with red light has been demonstrated to be effective in killing several human pathogens, including the oral bacterium, Porphyromonas gingivalis, a major pathogen in periodontitis. Killing was associated with alterations in the molecular masses of several outer membrane and plasma membrane proteins and these may be therapeutic targets for photodynamic therapy and other antimicrobial approaches. To identify these photolabile proteins, we have used a panel of monoclonal antibodies raised to whole P. gingivalis. A number of the antibodies recognized various photolabile proteins. Using a combination of Western blotting and protein sequencing the predominant photolabile proteins in P. gingivalis have been identified as the major secreted/cell surface proteases--Lys and Arg gingipain.

Staphylococcus aureus accessory regulators: expression within biofilms and effect on adhesion

Many of the genes encoding the virulence factors for Staphylococcus aureus are controlled by the accessory gene regulator (agr) and staphylococcal accessory regulator (sar). This regulation may be affected by the environment in which the organisms are grown. In the majority of ecosystems, bacteria grow attached to surfaces and form biofilms. We used S. aureus strains containing mutations inactivating agr and sar to determine whether the presence of these genes influences the attachment of the bacterium to a surface. We also used strains harbouring reporter constructs of the agr and sar operons to determine their expression in biofilms. The attachment study results showed that the sarA mutant strain adhered better to glass than did the agrA mutant or the wild type. There was an increased adherence to fibronectin-coated glass for all three strains compared to glass. Thus, these adhesion studies demonstrate that agr and sar have pleiotrophic effects on the surface expression of molecules responsible for binding to different substrata. In the biofilms higher numbers of bacteria and the greatest expression were observed at the base, but there were no observable differences between the reporter constructs. Expression of the agr and sar reporter fusions was significantly higher in the deepest layers of the biofilms where the greatest numbers of bacteria were also observed, perhaps as one might expect for genes that are regulated in a cell density dependent fashion.

Analysis of the effect of changing environmental conditions on the expression patterns of exported surface-associated proteins of the oral pathogen Actinobacillus actinomycetemcomitans

Actinobacillus actinomycetemcomitans has been specifically implicated in the aetiology of one or more of the periodontal diseases, conditions in which inflammation of the gums is associated with destruction of the alveolar bone supporting the teeth. In these diseases there is loss of attachment of the gums (gingivae) to the teeth forming a periodontal pocket. The microenvironment of this pocket is extremely complex and it is likely that there will be substantial variation in the environmental conditions operating in this habitat. The aim of the current investigation was to study the effect of disease-relevant environmental factors on the production and release of secreted surface- associated proteins of A. actinomycetemcomitans. These secreted proteins contain many of the virulence determinants of this organism. A range of environmental conditions were investigated: growth in a CO(2)-enriched aerobic atmosphere vs anaerobic growth, presence of serum or blood, biofilm vs planktonic mode of growth and iron depletion. Differential expression of a number of the secreted surface-associated proteins was observed under different growth conditions and these included the glycolytic enzyme triose phosphate isomerase. An ability to adapt to prevailing environmental conditions may facilitate the survival of the organism in the changing microIenvironment of the periodontal pocket.

Staphylococcus aureus fibronectin binding proteins are essential for internalization by osteoblasts but do not account for differences in intracellular levels of bacteria

Staphylococcus aureus is a major pathogen of bone that has been shown to be internalized by osteoblasts via a receptor-mediated pathway. Here we report that there are strain-dependent differences in the uptake of S. aureus by osteoblasts. An S. aureus septic arthritis isolate, LS-1, was internalized some 10-fold more than the laboratory strain 8325-4. Disruption of the genes for the fibronectin binding proteins in these two strains of S. aureus blocked their ability to be internalized by osteoblasts, thereby demonstrating the essentiality of these genes in this process. However, there were no differences in the capacity of these two strains to bind to fibronectin or osteoblasts. Analysis of the kinetics of internalization of the two strains by osteoblasts revealed that strain 8325-4 was internalized only over a short period of time (2 h) and to low numbers, while LS-1 was taken up by osteoblasts in large numbers for over 3 h. These differences in the kinetics of uptake explain the fact that the two strains of S. aureus are internalized by osteoblasts to different extents and suggest that in addition to the fibronectin binding proteins there are other, as yet undetermined virulence factors that play a role in the internalization process.

Identification of the exported proteins of the oral opportunistic pathogen Actinobacillus actinomycetemcomitans by using alkaline phosphatase fusions

A phoA fusion library of Actinobacillus actinomycetemcomitans genomic DNA has been screened to identify genes encoding exported and secreted proteins. A total of 8,000 colonies were screened, and 80 positive colonies were detected. From these, 48 genes were identified with (i) more than half having homology to known or hypothetical Haemophilus influenzae genes, (ii) 14 having no ascribed function, and (iii) 4 having very limited or no homology to known genes. The proteins encoded by these genes may, by virtue of their presence on the cell surface, be novel virulence determinants.

Cloning and expression of the Actinobacillus actinomycetemcomitans thioredoxin (trx) gene and assessment of cytokine inhibitory activity

Thioredoxin is a ubiquitous redox control and cell stress protein. Unexpectedly, in recent years, thioredoxins have been found to exhibit both cytokine and chemokine activities, and there is increasing evidence that this class of protein plays a role in the pathogenesis of inflammatory diseases. In spite of this evidence, it has been reported that the oral bacterium and periodontopathogen Actinobacillus actinomycetemcomitans secretes an immunosuppressive factor (termed suppressive factor 1 [SF1] [T. Kurita-Ochiai and K. Ochiai, Infect. Immun. 64:50-54, 1996]) whose N-terminal sequence, we have determined, identifies it as thioredoxin. We have cloned and expressed the gene encoding the thioredoxin of A. actinomycetemcomitans and have purified the protein to homogeneity. The A. actinomycetemcomitans trx gene has 52 and 76% identities, respectively, to the trx genes of Escherichia coli and Haemophilus influenzae. Enzymatic analysis revealed that the recombinant protein had the expected redox activity. When the recombinant thioredoxin was tested for its capacity to inhibit the production of cytokines by human peripheral blood mononuclear cells, it showed no significant inhibitory capacity. We therefore conclude that the thioredoxin of A. actinomycetemcomitans does not act as an immunosuppressive factor, at least with human leukocytes in cultures, and that the identity of SF1 remains to be elucidated.

Identification of the secreted macromolecular immunogens of Staphylococcus aureus by analysis of serum

The ability of sera to recognise secreted macromolecules of Staphylococcus aureus was examined by ELISA and Western immunoblotting. Individual secreted proteins were also studied using both human sera and sera from rabbits immunised with secreted macromolecules. Patients sera showed a wide range of IgG antibody titres to secreted macromolecules and whole bacteria. Controls showed a significantly lower IgG response. Western immunoblotting revealed that a significant number of secreted proteins were recognised by circulating IgG antibodies. Surprisingly, both the sera from controls and from patients recognised similar macromolecules including a number of potential virulence factors. The major difference was in the IgG binding to a 16-kDa component, which was recognised by the majority of the sera from infected individuals, but only by a small number of sera from healthy controls. The higher incidence of antibodies recognising the 16 kDa component may be related to our earlier finding that the major bone resorbing component of S. aureus is a heterodimeric protein containing a 16-kDa subunit, the activity of which could be blocked by sera.

Prevalence of obesity and diabetes in patients with cryptogenic cirrhosis: a case-control study

It has recently been suggested that nonalcoholic steatohepatitis (NASH) is an under-recognized cause of cryptogenic cirrhosis (CC) on the basis of higher prevalence of obesity and type II diabetes among these patients. To test this hypothesis, we studied 65 consecutive patients with advanced cirrhosis (Child-Pugh Score >/= 7) of undetermined etiology (CC) from our active waiting list for liver transplantation in January 1993, 1996, and 1999. For each patient, we selected 2 age- and sex-matched controls from the corresponding lists. The prevalence of obesity (defined as body mass index [BMI] >/= 30) and diabetes were compared between the groups. Sixteen patients (and their 32 controls) with CC were excluded as further review of records suggested other possible etiologies. Thus, the final analysis included 49 patients and 98 controls. The etiology of cirrhosis in the control group was alcohol in 16.3%, chronic viral hepatitis in 30.6%, autoimmune hepatitis in 8.2%, and primary biliary cirrhosis (PBC) or primary sclerosing cholangitis in 35.7%. The prevalence of obesity (55% vs. 24%) and type II diabetes (47% vs. 22%) was significantly higher in patients with CC compared with controls. Twenty-three percent of patients with CC had both obesity and diabetes compared with 5% among controls (P =.002). There was no difference in the prevalence of hypercholesterolemia (serum cholesterol > 200 mg/dL) between the groups. In conclusion, patients with advanced CC are more likely to be obese and diabetic compared with age- and sex-matched patients with advanced cirrhosis. This supports the hypothesis that NASH may be an etiological factor in some of the patients with CC.

Prevalence of obesity and diabetes in patients with cryptogenic cirrhosis: a case-control study

It has recently been suggested that nonalcoholic steatohepatitis (NASH) is an under-recognized cause of cryptogenic cirrhosis (CC) on the basis of higher prevalence of obesity and type II diabetes among these patients. To test this hypothesis, we studied 65 consecutive patients with advanced cirrhosis (Child-Pugh Score >/= 7) of undetermined etiology (CC) from our active waiting list for liver transplantation in January 1993, 1996, and 1999. For each patient, we selected 2 age- and sex-matched controls from the corresponding lists. The prevalence of obesity (defined as body mass index [BMI] >/= 30) and diabetes were compared between the groups. Sixteen patients (and their 32 controls) with CC were excluded as further review of records suggested other possible etiologies. Thus, the final analysis included 49 patients and 98 controls. The etiology of cirrhosis in the control group was alcohol in 16.3%, chronic viral hepatitis in 30.6%, autoimmune hepatitis in 8.2%, and primary biliary cirrhosis (PBC) or primary sclerosing cholangitis in 35.7%. The prevalence of obesity (55% vs. 24%) and type II diabetes (47% vs. 22%) was significantly higher in patients with CC compared with controls. Twenty-three percent of patients with CC had both obesity and diabetes compared with 5% among controls (P =.002). There was no difference in the prevalence of hypercholesterolemia (serum cholesterol > 200 mg/dL) between the groups. In conclusion, patients with advanced CC are more likely to be obese and diabetic compared with age- and sex-matched patients with advanced cirrhosis. This supports the hypothesis that NASH may be an etiological factor in some of the patients with CC.

Identification of a novel gene cluster encoding staphylococcal exotoxin-like proteins: characterization of the prototypic gene and its protein product, SET1

We report the discovery of a novel genetic locus within Staphylococcus aureus that encodes a cluster of at least five exotoxin-like proteins. Designated the staphylococcal exotoxin-like genes 1 to 5 (set1 to set5), these open reading frames have between 38 and 53% homology to each other. All five proteins contain consensus sequences that are found in staphylococcal and streptococcal exotoxins and toxic shock syndrome toxin 1 (TSST-1). However, the SETs have only limited overall sequence homology to the enterotoxins and TSST-1 and thus represent a novel family of exotoxin-like proteins. The prototypic gene in this cluster, set1, has been cloned and expressed. Recombinant SET1 stimulated the production of interleukin-1beta, interleukin-6, and tumor necrosis factor alpha by human peripheral blood mononuclear cells. PCR analysis revealed that set1 was distributed among other strains of S. aureus but not in the other staphylococcal species examined. Sequence analysis of the set1 genes from different strains revealed at least three allelic variants. The protein products of these allelic variants displayed a 100-fold difference in their cytokine-inducing potency. The distribution of allelic variants of the set genes among strains of S. aureus may contribute to differences in the pathogenic potential of this bacterium.

Rapid screening for putative exported proteins from Staphylococcus aureus using alkaline phosphatase as a reporter molecule

Staphylococcus aureus causes a wide range of infections in humans, ranging from superficial skin infections to the more serious toxin-mediated diseases such as toxic shock syndrome. Owing to the increasing resistance of this bacterium to a wide range of antibiotics, the need to determine the virulence factors involved in infection is becoming more important as these molecules are potential therapeutic targets. In this study, we have screened for putative exported proteins from S. aureus on the basis that these proteins are likely to be the first point of contact between the bacterium and host during infection. We have constructed gene fusions between S. aureus DNA and a truncated version of the Escherichia coli phoA gene, and we report on the characterization of the recombinants exhibiting alkaline phosphatase activity. As well as known S. aureus proteins, we have identified a number of putative open reading frames that encode proteins similar to those from nonstaphylococcal species and also unique proteins that do not have any homologues on the current databases.

Primaty cutaneous histoplasmosis

A 29-year old woman presented with diffuse swelling of the base of the right thumb along with ulceration. X-ray indicated bony damage. Histopathology showed PAS positive intracellular organisms suggestive of histoplasmosis. We are reporting a very rare case of primary cutaneous histoplasmosis from this part of the country.

Mechanisms of internalization of Staphylococcus aureus by cultured human osteoblasts

Staphylococcus aureus is an important bone pathogen, and evidence shows that this organism is internalized by chick osteoblasts. Here we report that S. aureus is internalized by human osteoblasts. Internalization was inhibited by monodansylcadaverine and cytochalasin D and to a lesser extent by ouabain, monensin, colchicine, and nocodazole. We propose that internalization occurs via a receptor-mediated pathway, requiring the participation of cytoskeletal elements, principally actin.

Molecular chaperones stimulate bone resorption

Molecular chaperones, also known as heat shock proteins (hsp), are intracellular proteins found in all cells that catalyze protein folding. We have discovered that one class of bacterial molecular chaperone, the chaperonins, are potent inducers of bone resorption. To address the question of whether the osteolytic activity of the chaperonins was unique to this protein class, or was a common attribute of molecular chaperones generally, we have examined a number of bacterial and mammalian molecular chaperones for activity in the murine calvarial bone resorption assay. All the Escherichia coli molecular chaperones (groEL, groES, and dnaK) were active. The osteolytic activity of groEL was inhibited by indomethacin and the natural antagonist of interleukin-1 receptor antagonist (IL-1ra) but was unaffected by neutralization of tumor necrosis factor (TNF) or inhibition of 5-lipoxygenase. Mammalian molecular chaperones of molecular mass 27, 47, 70, and 90 kDa were also tested and, with the exception of the 47 kDa protein, all showed activity in the murine calvarial assay. Molecular chaperones appear, therefore, to have the capacity to modulate the cellular processes in bone explant cultures, resulting in resorption of the calcified matrix. The possibility that these proteins could play a role in the normal or pathological remodeling of bone is discussed.

Surface-associated protein from Staphylococcus aureus stimulates osteoclastogenesis: possible role in S. aureus-induced bone pathology

OBJECTIVE

Staphylococcus aureus is the cause of bone destruction in osteomyelitis, bacterial arthritis and orthopaedic implant failure. We have previously shown that gentle saline extraction of S. aureus has revealed the presence of an extremely potent stimulator of osteoclast activation in both the murine calvarial bone resorption assay and the isolated chick osteoclast resorption assay. In order to investigate the mechanism of action of this surface-associated material (SAM), we have investigated its capacity to recruit osteoclasts.

METHODS

The murine bone marrow osteoclast recruitment assay was used. The ability of the recruited cells to resorb dentine slices was also investigated. Results. The SAM from S. aureus dose dependently stimulated tartrate-resistant acid phosphatase (TRAP)-positive osteoclast formation and pit formation on dentine slices. Neutralization of the cytokines tumour necrosis factor alpha and interleukin (IL)-6 totally inhibited, but antagonism of IL-1 only partially blocked, the stimulated maturation of osteoclast-like cells.

CONCLUSION

These findings suggest that bone destruction associated with local infection by S. aureus is due to the stimulation of osteoclast formation induced by the action of the easily solubilized SAM, and could explain the large numbers of osteoclasts found in infarcted bone in osteomyelitis.

The Escherichia coli chaperonin 60 (groEL) is a potent stimulator of osteoclast formation

Chaperonins (cpns) are intracellular oligomeric protein complexes that fold and refold proteins in a catalytic manner and aid in the transmembrane transport of cellular proteins. We reported previously that the lipopolysaccharide-free recombinant cpn60 of Escherichia coli (groEL) is able to stimulate the breakdown of murine calvarial bone in culture and showed that such resorption is potently inhibited by an inhibitor of the enzyme cyclo-oxygenase and to a lesser extent by inhibitors of 5-lipoxygenase. In this study, we have investigated the effects of groEL on the resorptive activity and formation of osteoclasts in culture. In low density, osteoclast-containing cultures from neonatal rats incubated for 24 or 96 h on dentine discs, groEL (1-1000 ng/ml) stimulated resorption pit formation up to 4-fold, but this effect was essentially dependent on cell number. Using 12-day cultures of mouse bone marrow to assess osteoclast recruitment, groEL (1-1000 ng/ml) caused a dramatic dose-dependent stimulation of the formation of tartrate-resistant acid phosphatase-positive multinucleated cells and the resorption of the dentine on which bone marrow cells were cultured. Osteoclast formation elicited by groEL was almost completely abolished by indomethacin, an inhibitor of cyclo-oxygenase, but was unaffected by inhibitors of 5-lipoxygenase, suggesting that prostaglandins but not leukotrienes may mediate the action of groEL on osteoclastogenesis. It is possible that bacterial cpn60s such as groEL may play a role in the osteolysis associated with bone infections. Whether endogenous ("self") chaperonins have a role in other bone loss disorders, such as osteoporosis, is an intriguing possibility.

Homogeneous Escherichia coli chaperonin 60 induces IL-1 beta and IL-6 gene expression in human monocytes by a mechanism independent of protein conformation

Escherichia coli chaperonin (cpn) 60 (groEL) is a protein-folding oligomer lacking tryptophan residues that copurifies with tryptophan-containing proteins and peptides. Cpn 60 is a major immunogen in infectious diseases, and evidence suggests that groEL and mycobacterial cpn 60s can induce cytokine synthesis, stimulate cytokine-dependent bone resorption, and up-regulate expression of vascular endothelial cell adhesion molecules. Whether such activities are due to the cpn 60 or to the copurifying/contaminating proteins/peptides has not been determined. Here we report a method for removing the protein contaminants of groEL and demonstrate that this, essentially homogeneous, groEL remains a potent inducer of human monocyte IL-1beta and IL-6 production. Contaminating peptides had no cytokine-inducing activity and did not synergize with purified groEL. The LPS inhibitor polymyxin B and the CD14-neutralizing Ab MY4 had no inhibitory action on groEL demonstrating that activity is not due to LPS contamination. Heating groEL had no effect on its capacity to stimulate human monocytes to secrete IL-6. Proteolysis of groEL with trypsin, sufficient to produce low molecular mass peptides, also had no inhibitory effect. Thus, we conclude that groEL is a potent inducer of monocyte proinflammatory cytokine production, which acts through the binding of nonconformational peptide domains that are conserved after proteolysis. These data suggest that if groEL was released from bacteria it could induce prolonged tissue pathology by virtue of its cytokine-inducing activity and its resistance to proteolytic inhibition of bioactivity.

Molecular characterization of an outer membrane protein of Actinobacillus actinomycetemcomitans belonging to the OmpA family

The major outer membrane protein (OMP) of Actinobacillus actinomycetemcomitans is an OmpA homolog that demonstrates electrophoretic heat modifiability. The gene encoding this protein was isolated from a genomic library of A. actinomycetemcomitans NCTC 9710 by immunoscreening with serum from a patient with localized juvenile periodontitis. Expression of the cloned gene in Escherichia coli and subsequent Western blot analysis revealed a protein with an approximate molecular mass of 34 kDa. The amino acid sequence predicted from the cloned gene demonstrated that the mature protein had a molecular mass of 34,911 Da and significant identity to members of the OmpA family of proteins. We have named the major OMP of A. actinomycetemcomitans Omp34, and its corresponding gene has been named omp34.

Werner's Syndrome

A 41-year old unmarried man presented with erosions, ulcers and keratosis of tendoachilles. He was short statured and had features of premature aging, sclerosis of the skin of the limbs and hypogonadism. The head was small with a beak-like nose. Investigations revealed diabetes mellitus, generalised osteoporosis, calcification of blood vessel walls and microsplanchia of kidneys. All the features suggested a diagnosis of Werners's syndrome.

Mycobacterium tuberculosis chaperonin 10 stimulates bone resorption: a potential contributory factor in Pott's disease

Pott's disease (spinal tuberculosis), a condition characterized by massive resorption of the spinal vertebrae, is one of the most striking pathologies resulting from local infection with Mycobacterium tuberculosis (Mt; Boachie-Adjei, O., and R.G. Squillante. 1996. Orthop. Clin. North Am. 27:95-103). The pathogenesis of Pott's disease is not established. Here we report for the first time that a protein, identified by a monoclonal antibody to be the Mt heat shock protein (Baird, P.N., L.M. Hall, and A.R.M. Coates. 1989. J. Gen. Microbiol. 135:931-939) chaperonin (cpn) 10, is responsible for the osteolytic activity of this bacterium. Recombinant Mt cpn10 is a potent stimulator of bone resorption in bone explant cultures and induces osteoclast recruitment, while inhibiting the proliferation of an osteoblast bone-forming cell line. Furthermore, we have found that synthetic peptides corresponding to sequences within the flexible loop and sequence 65-70 of Mt cpn10 may comprise a single conformational unit which encompasses its potent bone-resorbing activity. Our findings suggest that Mt cpn10 may be a valuable pharmacological target for the clinical therapy of vertebral tuberculosis and possibly other bone diseases.

Bacterial porins stimulate bone resorption

Porins are abundant outer membrane proteins of gram-negative bacteria involved in transport of low-molecular-mass molecules. During the past decade, porins from a number of bacteria have also been shown to have proinflammatory activities including inducing the synthesis of proinflammatory mediators (cytokines, platelet-activating factor, and nitric oxide) in cultured cells and inducing inflammation in vivo. With this range of actions, it was possible that porins could also interact with bone cells to cause aberrant bone remodeling and that this could contribute to the bone destruction seen in gram-negative bone infections. By using purified preparations of Salmonella typhimurium and Pseudomonas aeruginosa porins, in the presence of polymyxin B, it was possible to induce concentration-dependent loss of calcium from cultured murine calvaria at porin concentrations in the range of 1 to 10 nM. The mechanism of action of the porins was determined by the inclusion of inhibitors of cyclooxygenase or inflammatory cytokines in the culture media. The bone-resorbing activity of both porins was not inhibited by the cyclooxygenase inhibitor indomethacin or by neutralizing the activity of tumor necrosis factor. Indeed, relatively high concentrations of these agents produced an unexpected increase in the bone resorption induced by the porins. In contrast, porin-induced bone resorption could be inhibited by relatively high concentrations of the natural inhibitor of interleukin-1 (IL-1 receptor antagonist). It appears that these porins stimulate bone resorption by a mechanism distinct from that of lipopolysaccharide, and the possibility therefore exists that porins play a role in bone destruction in gram-negative bacterial infections of bone.

Clinical isolates of Staphylococcus aureus have osteolytic surface proteins and a proportion of the population have antibodies that block this activity: is this of prognostic significance?

Staphylococcus aureus is directly implicated in the bone destruction associated with infected orthopaedic implants and bacterial arthritis. The Oxford (laboratory) strain of this organism has surface-associated proteins (SAPs) which have potent osteolytic activity. In this study, we have examined the osteolytic activity of SAPs from clinical isolates and also investigated the role of the humoral immune response to such proteins. Nine patients with infected orthopaedic prostheses or infective arthritis, and six volunteers not suffering from overt S. aureus infection, were examined. The sera from 5/9 patients and 4/6 volunteers were able to neutralize the osteolytic activity of the SAPs. The SAPs were extracted from four clinical isolates and were found to have osteolytic activity, but with a wide range of efficacies and potencies. All four patients from whom the clinical isolates were obtained had serum IgG antibodies to the surface proteins from their autologous isolates as determined by ELISA. In conclusion, clinical isolates of S. aureus contain osteolytic SAPs which may be responsible for bone destruction. Apparently disease-free individuals and patients have antibodies able to block this activity. However, since the capacity of patients' sera to neutralize the activity of the SAPs derived from their own S. aureus isolate was not investigated, it is unclear whether these findings are of prognostic value.

Bacterially induced bone destruction: mechanisms and misconceptions

Normal bone remodelling requires the coordinated regulation of the genesis and activity of osteoblast and osteoclast lineages. Any interference with these integrated cellular systems can result in dysregulation of remodelling with the consequent loss of bone matrix. Bacteria are important causes of bone pathology in common conditions such as periodontitis, dental cysts, bacterial arthritis, and osteomyelitis. It is now established that many of the bacteria implicated in bone diseases contain or produce molecules with potent effects on bone cells. Some of these molecules, such as components of the gram-positive cell walls (lipoteichoic acids), are weak stimulators of bone resorption in vitro, while others (PMT, cpn60) are as active as the most active mammalian osteolytic factors such as cytokines like IL-1 and TNF. The complexity of the integration of bone cell lineage development means that there are still question marks over the mechanism of action of many well-known bone-modulatory molecules such as parathyroid hormone. The key questions which must be asked of the now-recognized bacterial bone-modulatory molecules are as follows: (i) what cell population do they bind to, (ii) what is the nature of the receptor and postreceptor events, and (iii) is their action direct or dependent on the induction of secondary extracellular bone-modulating factors such as cytokines, eicosanoids, etc. In the case of LPS, this ubiquitous gram-negative polymer probably binds to osteoblasts or other cells in bone through the CD14 receptor and stimulates them to release cytokines and eicosanoids which then induce the recruitment and activation of osteoclasts. This explains the inhibitor effects of nonsteroidal and anticytokine agents on LPS-induced bone resorption. However, other bacterial factors such as the potent toxin PMT may act by blocking the normal maturation pathway of the osteoblast lineage, thus inducing dysregulation in the tightly regulated process of resorption and replacement of bone matrix. At the present time, it is not possible to define a general mechanism by which bacteria promote loss of bone matrix. Many bacteria are capable of stimulating bone matrix loss, and the information available would suggest that each organism possesses different factors which interact with bone in different ways. With the rapid increase in antibiotic resistance, particularly with Staphylococcus aureus and M. tuberculosis, organisms responsible for much bone pathology in developed countries only two generations ago, we would urge that much greater attention should be focused on the problem of bacterially induced bone remodelling in order to define pathogenetic mechanisms which could be therapeutic targets for the development of new treatment modalities.

Molecular chaperones and disease

Molecular chaperones are intracellular protein-folding proteins which form part of an ancient cellular response to stress called the heat shock response. They have been the focus for attention during the last decade because of the discovery of their vital role in cell functioning. In very recent years additional roles for these 'topologically-active' proteins in the process of tissue pathology and its treatment have been indicated and are reviewed.

Surface-associated material from the bacterium Actinobacillus actinomycetemcomitans contains a peptide which, in contrast to lipopolysaccharide, directly stimulates fibroblast interleukin-6 gene transcription

The oral commensal Gram-negative bacterium Actinobacillus actinomycetemcomitans is believed to be the causative organism of localized juvenile periodontitis, a disease in which there is rapid loss of alveolar bone supporting the teeth. Previously, we have reported that gentle saline extraction of this bacterium removed a loosely adherent proteinaceous fraction from the cell surface of the bacterium, which we have termed surface-associated material. This material contained potent bone-resorbing activity. We now report that surface-associated material is also a potent stimulator of cytokines, and in particular, interleukin-6 (IL-6) synthesis, while the lipopolysaccharide from this bacterium is only a weak stimulator of IL-6 synthesis by fibroblasts and monocytes. In contrast to enteric lipopolysaccharide (LPS), which induces fibroblast IL-1, IL-6 and tumour necrosis factor (TNF) alpha synthesis, surface-associated material stimulated gingival fibroblasts to synthesize only IL-6, with no induction of IL-1 or TNF (the normal inducers of IL-6 synthesis). Reverse transcriptase PCR also failed to detect mRNA for IL-1 or TNF in surface-associated-material-stimulated fibroblasts, although both mRNAs were present in Escherichia coli LPS-stimulated cells. Neutralizing antibodies to IL-1 and/or TNF or the natural IL-1 receptor antagonist (IL-1ra) inhibited enteric LPS-induced IL-6 synthesis, but did not inhibit surface-associated-material-induced synthesis. In addition, dexamethasone, which completely suppressed LPS-induced IL-6 synthesis, only inhibited surface-associated-material-induced IL-6 synthesis by 50%. This suggests that the active constituent in the surface-associated material stimulates IL-6 gene transcription by a transcriptional control mechanism distinct to that of E. coli LPS. The IL-6 stimulating activity of the surface-associated material is inhibited by both heat and trypsin, suggesting that it is proteinaceous. The activity has been isolated using anion-exchange, reverse-phase and size-exclusion HPLC. The active moiety is a peptide of molecular mass 2kDa which may be the product of a bacterial short open reading frame.

The potent bone-resorbing mediator of Actinobacillus actinomycetemcomitans is homologous to the molecular chaperone GroEL

Actinobacillus actinomycetemcomitans is a Gram-negative bacterium implicated in the pathology of localized juvenile periodontitis, a condition involving rapid destruction of alveolar bone. We have established that gentle extraction of this bacterium in saline releases a proteinaceous fraction (which we have termed surface-associated material [SAM] which has potent osteolytic activity in the murine calvarial bone resorption assay. Fractionation of the SAM has now revealed that activity is associated with a 62-kD protein. This bone-resorbing activity can be blocked by a monoclonal antibody (raised to the whole bacterium) that is claimed to recognize a protein homologous to the Escherichia coli molecular chaperone GroEL. Purification of this bone-resorbing protein to homogeneity has been achieved by a combination of anion exchange, gel filtration, and ATP-affinity chromatography and the NH2-terminal sequence shows > 95% homology to E. coli GroEL. This GroEL homologue is found in the SAM of A. actinomycetemcomitans but is not found in the osteolytically active SAM from other Gram-negative or Gram-positive bacteria. The GroEL protein from E. coli, but not from Mycobacterium tuberculosis and Mycobacterium leprae, also showed activity in the bone resorption assay. We believe this to be the first observation that a molecular chaperone has the capacity to stimulate the breakdown of connective tissue.

Characterization of an antiproliferative surface-associated protein from Actinobacillus actinomycetemcomitans which can be neutralized by sera from a proportion of patients with localized juvenile periodontitis

The gentle agitation of suspensions of Actinobacillus actinomycetemcomitans serotype a, b, or c in saline resulted in the release of a proteinaceous surface-associated material (SAM) which produced a dose-dependent inhibition of tritiated thymidine incorporation by the osteoblast-like cell line MG63 in culture. This cell line was sensitive to low concentrations of SAM (50% inhibitory concentration, 200 ng/ml for serotype c). Immunoglobulin G antibodies to constituents of the SAM were found in the blood of patients with localized juvenile periodontitis (LJP). Sera from 9 of 16 patients with LJP significantly neutralized the antiproliferative activity of the SAM, while sera from 15 controls, with no evidence of periodontal disease, were unable to neutralize this activity. Neutralization was not directly related to the patient's antibody titer to the whole SAM. Characterization of the antiproliferative activity in the SAM demonstrated that it was not cytotoxic and was heat and trypsin sensitive. The active component separated in a well-defined peak in anion-exchange high-performance liquid chromatography (HPLC) which, when further analyzed by size exclusion HPLC, revealed a single active peak, which had an apparent molecular mass of approximately 8 kDa. The lipopolysaccharide from A. actinomycetemcomitans was only weakly active. SAM from Porphyromonas gingivalis W50 and Eikenella corrodens NCTC 10596 did not exhibit any antiproliferative activity with this cell line, even at concentrations as high as 10 micrograms/ml. This study has shown that SAM from A. actinomycetemcomitans contains a potent antiproliferative protein whose activity can be neutralized by antibodies in the sera from some patients with LJP.

Studies on the immune response of foot-and-mouth disease vaccine type Asia-1 in pregnant ewes, lambs and evaluation of type O vaccine by challenge

Seven pregnant ewes at the 10th to 12th week of pregnancy were vaccinated with foot-and-mouth disease (FMD) vaccine type Asia-1. All pregnant animals responded well with antibody production without any adverse effects. The maximum antibody titer was noted 3 to 4 weeks after the vaccination. In the colostrum a high level of maternal antibodies persisted from 12 hrs to 6 weeks after birth. Irrespective of the presence of the maternal antibodies, the vaccinated lambs responded with antibody production within the first week of vaccination. The antibodies persisted up to the 12th week of vaccination. In another experiment five sheep were vaccinated with FMD type O vaccine and challenged with 10,000 TCID50 of virulent type O cell culture-adapted virus. The antibody titers in the vaccinated animals prior to challenge ranged between 1.26 to 1.65, while the four control sheep remained free from detectable antibody against virus type O. Pyrexia and viraemia developed present in all the control sheep but were absent in the vaccinated ones. Characteristic primary lesions on the dorsum of the tongue were observed after 48 hrs of virus challenge in the control sheep but were absent in the vaccinated ones.

Demonstration of antibodies against foot and mouth disease virus (FMDV) type O and Asia-1 in non-descriptive crossbred calves

Sera from non-descriptive crossbred calves were screened for the presence of neutralizing antibodies against FMDV type O and Asia-1 for a period up to 215 days. The antibody titer of 16 remained constant up to 215 days against type O and up to 190 days against type Asia-1 virus in some animals. In majority of the animals the antibody titers remained constant up to three months. The possible reason for a frequent breakdown of immunity in the vaccinated animals even 3-4 months after vaccination could be the fact that the calves were vaccinated repeatedly at their very early age with an ill effect of immunization in the presence of persisting antibodies.

A comparative study of the immune responses of sheep against foot-and-mouth disease virus types Asia-1 and O PEG-concentrated aluminium hydroxide gel and oil-adjuvanted vaccines

Foot-and-mouth disease (FMD) vaccines prepared against types Asia-1 and O PEG-concentrated and adjuvanted with aluminium hydroxide gel were compared with oil-adjuvanted types Asia-1 and O vaccines in sheep. The study was conducted by inoculating 0.5 ml of monovalent vaccine under laboratory conditions and 1 ml dose of bivalent vaccine in field conditions. The antibody responses were monitored by serum neutralization and ELISA tests. The results indicate that PEG-concentrated gel vaccine was of comparable immunogenicity to oil-adjuvanted vaccine over a study period of 8 weeks. No significant difference was observed in the antibody response with monovalent or bivalent vaccine. However, to substantiate the present findings and reach a final conclusion, further studies with both vaccines may have to be carried out over a longer period of time.

A study on the immune response of sheep to foot and mouth disease virus vaccine type 'O' prepared with different inactivants and adjuvants

Foot and mouth disease virus (FMDV) type 'O' was inactivated either with formaldehyde or binaryethyleneimine (BEI). Vaccines were prepared with inactivated virus incorporating aluminum hydroxide gel or mineral oil as an adjuvant. The antibody response in sheep was monitored by serum neutralization and ELISA test for a period of six months. Significant difference in antibody response was not observed between vaccines inactivated with formaldehyde or BEI. On the other hand significant difference in the antibody response was noticed between alhydrogel and oil vaccines. The high titer of antibodies stimulated by oil adjuvant vaccines persisted longer than those of alhydrogel vaccines within the period of study.

A comparative study on the immune response of sheep to foot and mouth disease virus vaccine type Asia-1 prepared with different inactivants and adjuvants

Foot and mouth disease virus type Asia-1 was inactivated either with formaldehyde or binaryethylenimine (BEI). Inactivated vaccines were prepared incorporating aluminium hydroxide gel or mineral oil as an adjuvant. The antibody response to the adult sheep was studied by ELISA and SN test for a period of 6 months. There was no difference in the antibody response between vaccines inactivated with formaldehyde or BEI. Whereas significant difference in the antibody response was observed between gel and oil vaccines. The high titres of antibody stimulated by oil vaccines persisted longer than those of gel vaccines within the period of study.

Conditions for the assay of glutamate semialdehyde aminotransferase that overcome the problem of substrate instability

Investigations into the kinetic properties of glutamate semialdehyde aminotransferase, a key enzyme in the metabolic pathway leading to chlorophyll, are made difficult by the instability of the enzyme's substrate glutamate 1-semialdehyde. The rate of spontaneous disappearance of this compound from solution is shown to vary with the square of its concentration and to be pH-dependent. Thus using conditions appropriate to the assay of the enzyme, half of the substrate is lost from solution in a few minutes. Second-order rate constants for the reaction are determined and conditions are selected whereby the effects of the spontaneous reaction are rendered insignificant. The steady-state kinetic properties of the enzyme determined using these conditions are reported.

Direct identification and quantification of the cofactor in glutamate semialdehyde aminotransferase from pea leaves

Glutamate semialdehyde aminotransferase, a key enzyme in the synthetic pathway leading to chlorophyll was purified from pea (Pisum sativum) leaves. Although the preparation contained a single contaminant the enzyme could be unambiguously identified as a dimer of subunit molar mass 45 kDa having an absorption spectrum consistent with the presence of pyridoxamine phosphate as cofactor. The cofactor was released by treatment with strong phosphate at low pH and was identified and quantified fluorimetrically. The specific activity of the enzyme (1.4 mumol.min-1.mg-1; 23 nkatal.mg-1) is very much higher than previously reported.