Development of a Chinese-Indian hybrid (Chindian) rhesus macaque colony at the California National Primate Research Center by introgression

BACKGROUND

Fullbred Chinese and Indian rhesus macaques represent genetically distinct populations. The California National Primate Research Center introduced Chinese founders into its Indian-derived rhesus colony in response to the 1978 Indian embargo on exportation of animals for research and the concern that loss of genetic variation in the closed colony would hamper research efforts. The resulting hybrid rhesus now number well over a thousand animals and represent a growing proportion of the animals in the colony.

METHODS

We characterized the population genetic structure of the hybrid colony and compared it with that of their pure Indian and Chinese progenitors.

RESULTS

The hybrid population contains higher genetic diversity and linkage disequilibrium than their full Indian progenitors and represents a resource with unique research applications.

CONCLUSIONS

The genetic diversity of the hybrids indicates that the strategy to introduce novel genes into the colony by hybridizing Chinese founders and their hybrid offspring with Indian-derived animals was successful.

Outer membrane proteins of wild-type and intimin-deficient enteropathogenic Escherichia coli induce Hep-2 cell death through intrinsic and extrinsic pathways of apoptosis

Enteropathogenic Escherichia coli cause protracted diarrhoea and malnutrition in infants by cytoskeletal depolymerisation and effacement of enterocyte microvilli. In this study, outer membrane proteins of wild-type enteropathogenic E. coli and an intimin-deficient mutant are shown to induce apoptosis by up-regulation of tumour necrosis factor alpha and activation of c-jun N-terminal kinase. Fluorescence-activated cell sorter analysis revealed apoptosis of cells treated with outer membrane proteins of wild-type and intimin-deficient strains. Proteinase K treatment of outer membrane proteins reduced apoptosis significantly, as did neutralising tumour necrosis factor alpha with specific antibodies. Elevated tumour necrosis factor receptor 1-associated death domain and caspase-3 expression were also observed on treatment with both types of outer membrane proteins. Furthermore, apoptosis was associated with suppression of Bcl-2 protein expression, up-regulation of Bax mRNA levels and increased cytochrome c release from mitochondria. Elevated phospho-c-jun N-terminal kinase, c-jun mRNA and activator protein-1 expression were observed, and phosphorylation of activator protein-1 was also observed by DNA-binding assays. Inhibition of c-jun N-terminal kinase, but not inhibition of p38 mitogen-activated protein kinase, resulted in reduction of tumour necrosis factor alpha mRNA levels and caspase-3 protein levels, and a reduction in apoptosis as observed by fluorescence-activated cell sorter analysis. From the host point of view, this study suggests a possible interplay between the death receptor and mitochondrial pathways when cell-free bacterial outer membrane preparations are used to trigger apoptosis.

Laparoscopic lateral pancreaticojejunostomy: a new remedy for an old ailment

BACKGROUND

Lateral pancreaticojejunostomy is considered as the standard surgery for chronic pancreatitis. Yet there are very few reports of this procedure being done laparoscopically. We present our experience with laparoscopic lateral pancreaticojejunostomy till date and describe our technique.

MATERIAL AND METHOD

Since 1997, we have done 12 laparoscopic lateral pancreatojejunostomies. There were 9 females and 3 males and the average age was 29.3 years. The indication for surgery in all patients was intractable abdominal pain and significant weight loss. Additionally, two patients were also suffering from pancreatic ascites.

RESULTS

The average diameter of the pancreatic duct was 14.7 mm. We used a four-port technique. All surgeries were completed without any conversion to open surgery. Post-operatively, there were no major morbidity and nil mortality. The average operating time was 172 minutes. Post-operative stay was short (average 5 days) and on median follow-up of 4.4 years, 83.3% patients had complete pain relief while 16.7% had partial relief. All patients had significant weight gain.

CONCLUSIONS

Laparoscopic lateral pancreaticojejunostomy is safe, effective and feasible in experience hands. Mastery of intracorporeal knotting and suturing techniques is mandatory before embarking on this surgery.

Enteropathogenic Escherichia coli outer membrane proteins induce changes in cadherin junctions of Caco-2 cells through activation of PKCalpha

Enteropathogenic Escherichia coli (EPEC) is a Gram-negative bacterial pathogen that adheres to human intestinal epithelial cells, resulting in watery, persistent diarrhoea. Despite the advances made in understanding EPEC-host cell interactions, the molecular mechanisms underlying watery diarrhoea have not been understood fully. Loss of transepithelial resistance and increased monolayer permeability by disruption of tight junctions has been implicated in this process. Apart from disruption of tight junctions, an important factor known to regulate monolayer permeability is E-cadherin and its interaction with beta-catenin, both of which constitute the adherens junctions. Our previous studies using HEp-2 cells demonstrated the morphological and cytoskeletal changes caused by cell-free outer membrane preparations (OMPs) of EPEC. In this study, we have shown that EPEC and its OMP induce significant changes in the adherens junctions of Caco-2 monolayers. We also observed significant phosphorylation of protein kinase Calpha (PKCalpha) in cells treated with either whole EPEC or its OMP. Immunoprecipitation of cell lysates with anti-E-cadherin and probing with phospho-PKCalpha monoclonal antibodies and anti-beta-catenins revealed that in these cells, phosphorylated PKCalpha is associated with cadherins, leading to the dissociation of the cadherin/beta-catenin complex. Immunofluorescence showed beta-catenins dissociated from the membrane-bound cadherins and redistributed into the cytoplasm. Expression of dominant negative PKCalpha reversed these effects caused by either whole EPEC or its OMP and also reduced the associated increase in monolayer permeability. It is possible that this mechanism may complement the earlier known pathways for loss of barrier function involving myosin light chain kinase activation and also may play a role in causing host cell death by apoptosis.

Enteropathogenic Escherichia coli Outer Membrane Proteins Induce iNOS by Activation of NF-κB and MAP Kinases

Enteropathogenic Escherichia coli (EPEC) infects the human intestinal epithelium and is a major cause of infantile diarrhea in developing countries. Nitric oxide (NO) is an important modulator of intestinal inflammatory response. The aim of the present study was to investigate whether EPEC outer membrane proteins (OMPs) up regulate epithelial cell expression of inducible nitric oxide synthase (iNOS) and to examine the role of NF-kappaB and MAP kinases (MAPK) on nitrite production. iNOS mRNA expression was assessed by RT-PCR. Nitrite levels were measured by Griess reaction. NF-kappaB activation by OMPs was evaluated by EMSA and immunoblotting was done to detect MAPK activation. EPEC OMP up regulated iNOS, induced nitrite production and NF-kappaB and MAPK were activated in caco-2 cells. The nitrite levels decreased when NF-kappaB and MAPK inhibitors were used. Thus, EPEC OMPs induce iNOS expression and NO production through activation of NF-kappaB and MAPK.

Extrusion of actin-positive strands from Hep-2 and Int 407 cells caused by outer membrane preparations of enteropathogenic Escherichia coil and specific attachment of wild type bacteria to the strands

Enteropathogenic Escherichia coli (EPEC) causes persistent infantile diarrhoea. This nontoxigenic E. coli exhibits a complicated pathogenic mechanism in which its outer membrane proteins and type III secretory proteins damage intestinal epithelium and cause diarrhoea. In accordance with this, our previous study using HEp-2 cells demonstrated cytopathic effects caused by cell-free outer membrane preparations of EPEC. In this study, we report the extrusion of actin-positive strands from HEp-2 and Int 407 cells when treated with outer membrane preparations. An interesting observation of this work, perhaps relevant to the characteristic localized three-dimensional colony formation of EPEC, is the attachment of a wild type EPEC strain to these actin-positive strands.

Extrusion of actin-positive strands from HEp-2 and Int 407 cells caused by outer membrane preparations of enteropathogenicEscherichia coliand specific attachment of wild type bacteria to the strands

Enteropathogenic Escherichia coli (EPEC) causes persistent infantile diarrhoea. This nontoxigenic E. coli exhibits a complicated pathogenic mechanism in which its outer membrane proteins and type III secretory proteins damage intestinal epithelium and cause diarrhoea. In accordance with this, our previous study using HEp-2 cells demonstrated cytopathic effects caused by cell-free outer membrane preparations of EPEC. In this study, we report the extrusion of actin-positive strands from HEp-2 and Int 407 cells when treated with outer membrane preparations. An interesting observation of this work, perhaps relevant to the characteristic localized three-dimensional colony formation of EPEC, is the attachment of a wild type EPEC strain to these actin-positive strands.Key words: enteropathogenic Escherichia coli, actin, outer membrane proteins, cytoskeletal elements.