Study Protocol--accurate assessment of kidney function in Indigenous Australians: aims and methods of the eGFR study

BACKGROUND

There is an overwhelming burden of cardiovascular disease, type 2 diabetes and chronic kidney disease among Indigenous Australians. In this high risk population, it is vital that we are able to measure accurately kidney function. Glomerular filtration rate is the best overall marker of kidney function. However, differences in body build and body composition between Indigenous and non-Indigenous Australians suggest that creatinine-based estimates of glomerular filtration rate derived for European populations may not be appropriate for Indigenous Australians. The burden of kidney disease is borne disproportionately by Indigenous Australians in central and northern Australia, and there is significant heterogeneity in body build and composition within and amongst these groups. This heterogeneity might differentially affect the accuracy of estimation of glomerular filtration rate between different Indigenous groups. By assessing kidney function in Indigenous Australians from Northern Queensland, Northern Territory and Western Australia, we aim to determine a validated and practical measure of glomerular filtration rate suitable for use in all Indigenous Australians.

METHODS/DESIGN

A cross-sectional study of Indigenous Australian adults (target n = 600, 50% male) across 4 sites: Top End, Northern Territory; Central Australia; Far North Queensland and Western Australia. The reference measure of glomerular filtration rate was the plasma disappearance rate of iohexol over 4 hours. We will compare the accuracy of the following glomerular filtration rate measures with the reference measure: Modification of Diet in Renal Disease 4-variable formula, Chronic Kidney Disease Epidemiology Collaboration equation, Cockcroft-Gault formula and cystatin C- derived estimates. Detailed assessment of body build and composition was performed using anthropometric measurements, skinfold thicknesses, bioelectrical impedance and a sub-study used dual-energy X-ray absorptiometry. A questionnaire was performed for socio-economic status and medical history.

DISCUSSION

We have successfully managed several operational challenges within this multi-centre complex clinical research project performed across remote North, Western and Central Australia. It seems unlikely that a single correction factor (similar to that for African-Americans) to the equation for estimated glomerular filtration rate will prove appropriate or practical for Indigenous Australians. However, it may be that a modification of the equation in Indigenous Australians would be to include a measure of fat-free mass.

Full length genomes of genotype IIIA Hepatitis A Virus strains (1995-2008) from India and estimates of the evolutionary rates and ages

With the changing epidemiology, outbreaks of Hepatitis A Virus (HAV) have been reported from different parts of India. To characterize HAV strains circulating in India (1995-2008), 6 full genome sequences of the predominant genotype, IIIA, were determined. Further, applying the Bayesian Markov Chain Monte Carlo (MCMC) framework to the full genomes of Indian HAV strains as well as other global strains (human as well as simian), we derived the mean nucleotide substitution rate and evolutionary timescales with emphasis on the age of genotype III and IIIA strains. The genomic length of all the 6 HAV isolates was 7464 nt excluding the poly A tract. Phylogenetic analysis confirmed that all the Indian isolates were close to Nor-21 (AJ299464) and HMH (AY644337) of subgenotype IIIA. The ORF of the isolates when compared within genotype III at amino acid level showed a highly conserved pattern. Under the best fit expansion population relaxed molecular clock model, the estimated mean substitution rate of the HAV full genomes (human and simian strains) was 1.73 x 10(-4) substitutions/site/year based on which the earliest transmission of HAV from simian to humans is estimated to have occurred about 3564 years ago. The mean substitution rate within human HAV full genomes under the same model was estimated to be 1.99 x 10(-4) substitutions/site/year. With this the mean age of genotype III strains was estimated to be 592 years while that of genotype IIIA was estimated to be 202 years. The time to the most common recent ancestor (tMRCA) of the Indian genotype IIIA isolates was calculated to be 116 years.

Multiwell micromechanical cantilever array reader for biotechnology

We use a multiwell micromechanical cantilever sensor (MCS) device to measure surface stress changes induced by specific adsorption of molecules. A multiplexed assay format facilitates the monitoring of the bending of 16 MCSs in parallel. The 16 MCSs are grouped within four separate wells. Each well can be addressed independently by different analyte liquids. This enables functionalization of MCS separately by flowing different solutions through each well. In addition, each well contains a fixed reference mirror which allows measuring the absolute bending of MCS. In addition, the mirror can be used to follow refractive index changes upon mixing of different solutions. The effect of the flow rate on the MCS bending change was found to be dependent on the absolute bending value of MCS. Experiments and finite element simulations of solution exchange in wells were performed. Both revealed that one solution can be exchanged by another one after 200 microl volume has flown through. Using this device, the adsorption of thiolated DNA molecules and 6-mercapto-1-hexanol on gold surfaces was performed to test the nanomechanical response of MCS.

Rapidly increasing prevalence of eosinophilic oesophagitis in Western Australia

AIM

To assess the prevalence of eosinophilic oesophagitis in a tertiary paediatric gastroenterology clinic population.

METHODS

A retrospective audit of Western Australian children investigated for oesophageal disease by paediatric gastroenterologists in the years 1995, 1999 and 2004. Macroscopic appearance of the oesophagus at endoscopy, original histological findings and diagnosis were recorded for each child. Biopsy specimens were blindly re-evaluated, with re-coded histological diagnoses compared with original reports. Age, sex and socioeconomic status were identified for each child.

RESULTS

The prevalence of eosinophilic oesophagitis in Western Australia increased over the decade 1995-2004, rising from 0.05 to 0.89 per 10 000 children, with a concomitant increase in the severity of oesophagitis as determined by inflammatory cell numbers and associated features of inflammation. Children diagnosed with eosinophilic oesophagitis had a median age of 78.9 months (6.58 years), with no associated predisposition by sex or socioeconomic status trend. Almost one third of cases were macroscopically normal at endoscopy. All children with an original diagnosis of eosinophilic oesophagitis had > or =40 eosinophils per high-power field.

CONCLUSION

Over the decade 1995-2004, a true increase was seen in the prevalence of eosinophilic oesophagitis, not accounted for by diagnostic shift. Histological samples should be taken at endoscopy to confirm or exclude the diagnosis of eosinophilic oesophagitis.

Transforming growth factor-betas in a rat model of neonatal posthaemorrhagic hydrocephalus

Posthaemorrhagic ventricular dilatation (PHVD) is a common complication of intraventricular haemorrhage in premature infants. The aim of this study was to investigate the role of transforming growth factor-betas (TGF-betas), a family of polypeptides with potent desmoplastic properties, in the aetiology of PHVD in a newly developed neonatal rat model of this disorder. Pups were injected with citrated rat blood or artificial cerebrospinal fluid (ACSF) into alternate lateral ventricles on postnatal days 7 and 8. The brains were perfusion-fixed 14 days later and immunohistochemistry was performed for TGF-beta1, -beta2 and -beta3, p44/42 mitogen-activated protein (MAP) kinases, and the extracellular matrix proteins laminin, vitronectin and fibronectin. Ventricular dilatation occurred in 58.3% of animals injected with blood and 36.7% of those injected with ACSF. Periventricular immunoreactivity for TGF-beta1 and -beta2 increased in injected animals irrespective of the presence or absence of ventricular dilatation, although the levels of both isoforms tended to be higher in animals with hydrocephalus. TGF-beta3 immunoreactivity was elevated in hydrocephalic rats only. The immunolabelling for phosphorylated p44/42 MAP kinases rose in a pattern similar to that for TGF-beta1 and -beta2. Expression of TGF-betas was accompanied by deposition of the extracellular matrix proteins fibronectin, laminin and vitronectin. The changes caused by injection of ACSF were the same as those caused by injection of blood. Our results raise the possibility that expression of TGF-betas, together with extracellular matrix protein deposition, may be involved in the development and/or maintenance of hydrocephalus after ventricular distension due to haemorrhage in the neonate.

Posthaemorrhagic ventricular dilatation: new mechanisms and new treatment

Post haemorrhagic ventricular dilatation is associated with a high rate of disability, multiple impairments and adverse effects of shunt surgery for hydrocephalus. Post haemorrhagic ventricular dilatation results initially from multiple small blood clots throughout the cerebrospinal fluid channels impeding circulation and re-absorption. Transforming growth factor beta is released into the cerebrospinal fluid and there is evidence that this cytokine stimulates the laying down of extracellular matrix proteins which produce permanent obstruction to the cerebrospinal fluid pathways. Prolonged raised pressure, pro-inflammatory cytokines and free radical damage from iron may contribute to periventricular white matter damage and subsequent disability. Interventions such as early lumbar punctures, diuretic drugs to reduce cerebrospinal fluid production and intraventricular fibrinolytic therapy have been tested and, not only fail to prevent shunt dependence, death or disability, but have significant adverse effects. Surgical interventions such as subcutaneous reservoir, external drain, choroid plexus coagulation and third ventriculostomy have not been subject to controlled trial. Ventriculoperitoneal shunt is not feasible in the early phase after intraventricular haemorrhage but, despite the problems with blockages and infections, remains the only option for infants with excessive head expansion over periods of weeks. We have piloted drainage, irrigation and fibrinolytic therapy as a way of removing blood early enough to stop the progressive deposition of matrix proteins, permanent hydrocephalus and shunt dependence.

Prediction of extubation failure in preterm infants

OBJECTIVE

To identify whether the results of assessment of respiratory muscle strength or respiratory load were better predictors of extubation failure in preterm infants than readily available clinical data.

PATIENTS

Thirty six infants, median gestational age 31 (range 25-36) weeks and postnatal age 3 (1-14) days; 13 were < 30 weeks of gestational age.

METHODS

Respiratory muscle strength was assessed by measurement of maximum inspiratory pressure generated during airway occlusion, and inspiratory load was assessed by measurement of compliance of the respiratory system.

RESULTS

Overall, seven infants failed extubation-that is, they required reintubation within 48 hours. These infants were older (p < 0.01), had a lower gestational age (p < 0.01), and generated lower maximum inspiratory pressure (p < 0.05) than the rest of the cohort. Similar results were found in the infants < 30 weeks of gestational age. Overall and in those < 30 weeks of gestational age, gestational age and postnatal age had the largest areas under the receiver operator characteristic curves.

CONCLUSION

In very premature infants, low gestational age and older postnatal age are better predictors of extubation failure than assessment of respiratory muscle strength or respiratory load.

Novel mutations in the SDHD gene in pedigrees with familial carotid body paraganglioma and sensorineural hearing loss

Paraganglioma (PGL) is a rare disorder characterized by tumors of the head and neck region. Between 10% and 50% of cases of PGL are familial, and the disease is autosomal dominant and subject to age-dependent penetrance and imprinting. The paraganglioma gene (PGL1) has been mapped to 11q22.3-q23, and recently germline mutations in the SDHD gene have been identified. The SDHD region contains another gene, DPP2/TIMM8B, the homolog of which causes dystonia and deafness seen in Mohr-Tranebjaerg syndrome. Using four PGL pedigrees, two of which exhibit coinheritance of PGL and sensorineural hearing loss or tinnitus, analysis of 14 microsatellite markers provided support for linkage to the PGL1 locus. Sequence analysis identified novel mutations in exon 1 and exon 3 of the SDHD gene, including a novel two base pair deletion in exon 3 creating a premature stop codon at position 67; a novel three base pair deletion in exon 3 resulting in the loss of Tyr-93; a missense mutation in exon 3 resulting in the substitution of Leu-81 for Pro-81; and a novel G-to-C substitution in exon 1 resulting in the substitution of Met-1 for Ile-1. No base changes were detected in the DPP2/TIMM8B gene. There was no apparent loss of heterozygosity at the site of the SDHD mutations. However, RT-PCR analysis of tumor samples showed monoallelic expression of the mutant (paternal) allele as expected for imprinting. This has not previously been shown for this disorder. The inheritance and expression of the SDHD gene is consistent with the PGL1 gene being subject to genomic imprinting.

Comparison of airway pressure and airflow triggering systems using a single type of neonatal ventilator

The performances of two triggering systems using a single neonatal ventilator type (SLE) were compared. Eight infants, gestational age 27-30 wk, were each recorded during two 1-h periods of patient-triggered ventilation (PTVs), one with airway pressure and one with airflow triggering. The airflow trigger had a shorter trigger delay (p < 0.02), higher sensitivity (p < 0.02) and lower asynchrony rate (p < 0.02).

CONCLUSION

In immature infants with mild respiratory distress syndrome using the SLE ventilator with inflation times of 0.3 to 0.36 sec, airflow triggering is more appropriate than airway pressure triggering.

An outbreak of multi-resistant Shigella sonnei in a long-stay geriatric nursing centre

An outbreak of Shigella sonnei infection in a long-stay nursing centre was detected during routine surveillance of notifications in July 1999. Subsequent investigations identified 13 cases of multi-resistant S. sonnei infection affecting nine staff, three community members associated with the centre and one resident of the centre. Each isolate of S. sonnei was genetically indistinguishable. The outbreak investigation identified contact with residents with vomiting and diarrhoea as a significant risk factor for infection amongst staff providing nursing care. This association, and the duration of the outbreak over several months, suggests that transmission was most likely person-to-person. This outbreak demonstrates the importance of infection control policies and hygiene measures in long-stay nursing facilities.

Discovery of a series of cyclohexylethylamine-containing protein farnesyltransferase inhibitors exhibiting potent cellular activity

Synthesis of a library of secondary benzylic amines based on the Sebti-Hamilton type peptidomimetic farnesyltransferase (FTase) inhibitor FTI-276 (1) led to the identification of 6 as a potent enzyme inhibitor (IC(50) of 8 nM) which lacked the problematic thiol residue which had been a common theme in many of the more important FTase inhibitors reported to date. It has previously been disclosed that addition of o-tolyl substitution to FTase inhibitors of the general description 2 had a salutary effect on both FTase inhibition and inhibition of Ras prenylation in whole cells. Combination of these two observations led us to synthesize 7, a potent FTase inhibitor which displayed an IC(50) of 0.16 nM for in vitro inhibition of FTase and an EC(50) of 190 nM for inhibition of whole cell Ras prenylation. Modification of 7 by classical medicinal chemistry led to the discovery of a series of potent FTase inhibitors, culminating in the identification of 25 which exhibited an IC(50) of 0.20 nM and an EC(50) of 4.4 nM. In vivo tests in a nude mouse xenograft model of human pancreatic cancer (MiaPaCa cells) showed that oral dosing of 25 gave rise to impressive attenuation of the growth of this aggressive tumor cell line.

Second-generation peptidomimetic inhibitors of protein farnesyltransferase demonstrating improved cellular potency and significant in vivo efficacy

The synthesis and evaluation of analogues of previously reported farnesyltransferase inhibitors, pyridyl benzyl ether 3 and pyridylbenzylamine 4, are described. Substitution of 3 at the 5-position of the core aryl ring resulted in inhibitors of equal or less potency against the enzyme and decreased efficacy in a cellular assay against Ras processing by the enzyme. Substitution of 4 at the benzyl nitrogen yielded 26, which showed improved efficacy and potency and yet presented a poor pharmacokinetic profile. Further modification afforded 30, which demonstrated a dramatically improved pharmacokinetic profile. Compounds 26 and 29 demonstrated significant in vivo efficacy in nude mice inoculated with MiaPaCa-2, a human pancreatic tumor-derived cell line.

Clinical and angiographic features in patients under 35 years with a first Q wave acute myocardial infarction

Sixty patients less than 35 years with a first Q wave acute myocardial infarction were prospectively studied to evaluate their features, risk factors and evidence of any viral infection. Typical chest pain was present in 98.3% with Q waves and ST segment elevation in all. None had hypotension or cardiogenic shock. Smoking was the most common risk factor (81.7%). Mean total cholesterol was 5.74 (+/-1.42) mmol/l. History of a viral illness was present in 28.3%, severe emotional stress in 21.7% and exhausting physical activity in 18.3%. Mean left ventricular diastolic and end systolic volumes were increased (90.11+/-22.5 ml/m2) and (46.62+/-20.46 ml/m2), respectively. The ejection fraction was depressed (49.71+/-1.6%). Triple vessel disease was seen only in 6.8 and 26.7% had insignificant or no coronary artery disease. Left anterior descending artery was most frequently involved (66%). None had left main involvement. Coronary ectasia was present in 11.7%, intracoronary thrombus in 28.3% and 40% had collaterals. Patients with no significant disease had no diabetes, a smaller number had a raised total cholesterol or smoked and had a lower ejection fraction. Patients from the Indian subcontinent who had fewer conventional risk factors, had more severe disease than those from the Arab world suggesting that other etiological factors need investigation.

Potent and orally bioavailable noncysteine-containing inhibitors of protein farnesyltransferase

Potent and orally bioavailable nonthiol-containing inhibitors of protein farnesyltransferase are described. Oral bioavailability was achieved by replacement of the pyridyl ether moiety of 1 with a 2-substituted furan ether to give 4. Potency was regained with 2,5-disubstituted furan ethers while maintaining the bioavailability inherent in 4. p-Chlorophenylfuran ether 24 is 0.7 nM in vitro (FTase) and is 32% bioavailable in the mouse, 30% bioavailable in rats, and 21% bioavailable in dogs.

Potent inhibitors of protein farnesyltransferase: heteroarenes as cysteine replacements

Synthesis and biological evaluation of heteroarenes as reduced cysteine replacements are described. Of the heteroaryl groups examined with respect to FT inhibitor FTI-276 (1), pyridyl was the replacement found to be most effective. Substitutions at C4 of the pyridyl moiety did not affect the in vitro activity. Compound 9a was found to have moderate in vivo bioavailability.

Potent and selective non-cysteine-containing inhibitors of protein farnesyltransferase

Potent and selective non-thiol-containing inhibitors of protein farnesyltransferase are described. FTI-276 (1) was transformed into pyridyl ether analogue 19. The potency of pyridyl ether 19 was improved by modification of the biphenyl core to that of an o-tolyl substituted biphenyl core to give 29. In addition to 0.4 nM in vitro potency, 29 displayed 350 nM potency in whole cells as the parent carboxylic acid. The o-tolyl biphenyl core dramatically and unexpectedly enhanced the potency of other compounds as exemplified by 46, 47, 48, and 49.

Simulated microgravity conditions enhance differentiation of cultured PC12 cells towards the neuroendocrine phenotype

We are studying microenvironmental cues which contribute to neuroendocrine organ assembly and tissue-specific differentiation. As our in vitro model, we cultured rat adrenal medullary PC12 pheochromocytoma cells in a novel cell culture system, the NASA rotating wall vessel (RWV) bioreactors. This "simulated microgravity" environment in RWV bioreactors, characterized by randomizing gravitational vectors and minimizing shear stress, has been shown to favor macroscopic tissue assembly and to induce tissue-specific differentiation. We hypothesized that the unique culture conditions in the RWV bioreactors might enhance the in vitro formation of neuroendocrine organoids. To test our hypothesis, we evaluated the expression of several markers of neuroendocrine differentiation in cultures of PC12 cells maintained for up to 20 d in the slow turning lateral vessel (STLV) type RWV. PC12 cell differentiation was assessed by morphological, immunological, biochemical and molecular techniques. PC12 cells, cultured under "simulated microgravity" conditions, formed macroscopic, tissue-like organoids several millimeters in diameter. Concomitantly, the expression of phenylethanolamine-N-methyl transferase (PNMT), but not of other catecholamine synthesizing enzymes, was enhanced. Increased PNMT expression, as verified on both the gene and protein level, was accompanied by an increase in the specific activity of the enzyme. Furthermore, after 20 d in culture in the STLV, we observed altered patterns of protein tyrosine phosphorylation and prolonged activation of c-fos, a member of the AP-1 nuclear transcription factor complex. We conclude that culture conditions in the RWV appear to selectively activate signal transduction pathways leading to enhanced neuroendocrine differentiation of PC12 cells.

Binding of the winged-helix transcription factor HNF3 to a linker histone site on the nucleosome

The transcription factor HNF3 and linker histones H1 and H5 possess winged-helix DNA-binding domains, yet HNF3 and other fork head-related proteins activate genes during development whereas linker histones compact DNA in chromatin and repress gene expression. We compared how the two classes of factors interact with chromatin templates and found that HNF3 binds DNA at the side of nucleosome cores, similarly to what has been reported for linker histone. A nucleosome structural binding site for HNF3 is occupied at the albumin transcriptional enhancer in active and potentially active chromatin, but not in inactive chromatin in vivo. While wild-type HNF3 protein does not compact DNA extending from the nucleosome, as does linker histone, site-directed mutants of HNF3 can compact nucleosomal DNA if they contain basic amino acids at positions previously shown to be essential for nucleosomal DNA compaction by linker histones. The results illustrate how transcription factors can possess special nucleosome-binding activities that are not predicted from studies of factor interactions with free DNA.

Effect of leucopelargonin derivative from Ficus bengalensis Linn. on diabetic dogs

Dimethoxy ether of Leucopelargonidin-3-0-alpha-L rhamnoside isolated from the bark of the Indian Banyan tree Ficus bengalensis Linn. was tested for antidiabetic effect. At a medium effective dose (100 mg/kg) on oral administration, the compound showed significant hypoglycemic and serum insulin raising action in normal as also moderately diabetic dogs (induced by alloxan) during a period of two hours. The mechanism of action of the glycoside compound seems to be similar to that of drugs which stimulate insulin secretion. On acute and chronic administration in single doses of 0.2-1.8 g/kg to different groups of mice and daily administration of 100, 250 and 500 mg/kg to rats for a period of one month respectively did not show any toxic effect and the compound was not lethal even at the high dose of 1.8 g/kg in experimental animals.

Evidence that TGF-beta can inhibit human T-lymphocyte proliferation through paracrine and autocrine mechanisms

Transforming growth factor-beta (TGF-beta) has been documented as having an inhibitory effect on the proliferation and growth of human T-lymphocytes. We examined the relative contribution of both exogenous and endogenous TGF-beta to this inhibitory action. Purified human peripheral blood T-cells were cultured with Con A (0.2 microgram/ml), washed with methyl mannopyranoside, and then cultured in rIL-2 (5 U/ml) with or without TGF-beta (80 pM). Proliferation, as measured by uptake of tritiated thymidine at 72 hr, was inhibited by added active TGF-beta. Addition of neutralizing anti-TGF-beta antibodies at the initiation of culture abrogated the antiproliferative effects of TGF-beta. A mink lung cell bioassay was used to measure endogenous TGF-beta production by the T-cells following transient acidification of the supernatants to activate latent TGF-beta. T-lymphocytes cultured with rIL-2 alone produced low levels of TGF-beta, first detectable at 72 hr. The addition of (active) TGF-beta to these cultures resulted in earlier and higher levels of endogenously produced latent TGF-beta protein. This was reflected at the mRNA level as well. The exogenously added active TGF-beta appeared to be depleted during the culture period, presumably by the activated T-cells, which exhibited elevated levels of types I, II, and III TGF-beta receptors. The increase in TGF-beta protein levels was due to endogenous TGF-beta synthesis and secretion as supported by a capture assay using 35S-labeled culture supernatants. These findings indicate that both paracrine and autocrine mechanisms are involved in the inhibitory effects of TGF-beta on the proliferation of normal human T-lymphocytes and suggest that other TGF-beta-producing cells can augment production of TGF-beta by activated T-lymphocytes.

Antidiabetic effects of a glycoside of leucopelargonidin isolated from Ficus bengalensis Linn

Glycoside of leucopelargonidin isolated from the bark of F. bengalensis demonstrated significant hypoglycemic, hypolipidemic and serum insulin raising effects in moderately diabetic rats with close similarities to the effects of a minimal dose of glibenclamide. The main difference observed in their effects was that the former significantly enhanced the fecal excretion of sterols and bile acids while the later has no such action even though both controlled hypercholesteremia.

Antidiabetic effect of a glycoside of pelargonidin isolated from the bark of Ficus bengalensis Linn

The antidiabetic effect of a dimethoxy derivative of perlargonidin 3-O-alpha-L rhamnoside (250 mg/kg, single dose study and 100 mg/kg/day long term study) isolated from the bark of Ficus bengalensis Linn. has been compared with that of glibenclamide (2 mg/kg and 0.5 mg/kg/day respectively) in moderately diabetic rats. The single dose glycoside treatment decreased fasting blood glucose by 19% and improved glucose tolerance by 29%. The corresponding effects of glibenclamide were 25% and 66% respectively over the control values. On one-month treatment the fasting blood glucose levels went down almost to half of the pretreatment levels in both the groups and their glucose tolerance improved by 41% in glibenclamide group and by 15% in glycoside treated group. Urine sugar decreased to traces in both the groups and they appeared healthy. In vitro studies showed that insulin secretion by beta-cells was more in presence of the pelargonidin derivative than in presence of a leucocyanidin derivative, reported to be a good anti-diabetic agent.

Comparative studies on the properties of glycogen phosphorylases from the foot muscles of two benthic bivalves, Sunetta scripta and Villorita cyprenoides, having different habitats

Glycogen phosphorylase (1,4-alpha-D-glucan:orthophosphate-alpha-D-glucosyl transferase, EC 2.4.1.1) was partially purified from two bivalves found in different habitats, viz. Villorita cyprenoides, an estuarine bivalve, and Sunetta scripta, a marine bivalve, and their properties compared with other animal phosphorylases. While the kinetic mechanism was same as that of phosphorylases from other animal sources, it differed in the control mechanism from other phosphorylases. The observed differences support the earlier finding that the control mechanism adopted by different animals is dependent on the evolutionary status and energy needs.

Effects of cigarette smoke on the immune response. II. Chronic exposure to cigarette smoke inhibits surface immunoglobulin-mediated responses in B cells

We have previously reported that chronic exposure of rats to cigarette smoke inhibits the antibody-forming cell (AFC) response to both T-dependent and T-independent antigens and may reflect B cell dysfunction. In this communication we extend these studies to show that T cell functions are normal in chronically smoke-exposed rats (SM) as judged by their responses to mitogens and "nominal" or alloantigens. While B cells from SM respond significantly to the B cell mitogen lipopolysaccharide (LPS), they fail to proliferate in response to anti-IgM (anti-mu) or to produce significant AFC response to sheep red blood cells. On the basis of the number of rosettes formed with trinitrophenylated (TNP) horse red blood cells; the frequency of TNP-binding cells (TNP-ABC) in the spleens of SM is comparable to sham control rats. However, the proliferation of TNP-ABC to TNP-Brucella abortus is significantly decreased in SM. These differences in SM B cell responses, i.e., between LPS and anti-mu/antigen, may to be related to the ability of LPS to bypass a portion of the membrane signal transduction cascade. These results suggest that cigarette smoke affects an early step(s) in the antigen-dependent B cell signal transduction pathway.

Bacterial contamination of contrast media stored after opening

A barium suspension, iohexol, iopamidol and ioxaglate which were diluted with tapwater and 0.9% NaCl and dextrose saline (4% and 0.18%) were made into aliquots of 10 ml and stored at 4 degrees C, room temperature and 37 degrees C for 8 weeks. Regular handling and bacterial cultures were performed. These studies confirmed that environmental organisms do contaminate these solutions and that they also support viable organisms, but do not become significantly colonized at room temperature or 4 degrees C. The solutions should be stored at room temperature or at 4 degrees C. The diluted barium solution was the contrast medium least contaminated and if it is not contra-indicated for other reasons should be used in preference to low osmolality water soluble contrast media on the basis of its cost, radiological contrast and low microbial contamination rate.

Cigarette smoke causes inhibition of the immune response to intratracheally administered antigens

Chronic inhalation of cigarette smoke in rats preferentially inhibited the plaque-forming cell (PFC) response of lung-associated lymph nodes (LALN) to sheep red blood cells (SRBC), compared to anatomically distant lymph nodes. Inhibition of the antibody response in LALN of smoke-exposed animals was first detected at 21 weeks of smoke inhalation and was well established by the 27th week of smoke exposure. After prolonged exposure (greater than 34 weeks) to cigarette smoke, similar smoke-induced changes in PFC response took place in other lymphoid tissues as well. Cigarette smoke affected the response of LALN cells to a T cell-dependent antigen (SRBC). Exposure to cigarette smoke, however, did not alter the relative percentages of W3/13-positive (T cells) or Ig-positive (B cells) cells, nor did it alter the relative percentages of T cell subsets as scored by their surface phenotypes, i.e., T helper (W3/25+) or T suppressor/cytotoxic (OX-8+) cells. The percentage of phagocytic cells and the accessory cell functions of macrophages remained comparable between sham and smoke-exposed animals. Exposure to cigarette smoke did not significantly alter the response of LALN cells to T cell mitogens (concanavalin A and phytohemagglutinin). However, response to a T cell-independent antigen trinitrophenyl Brucella abortus was also significantly reduced. These results show that cigarette exposure in the rat results in a decreased antibody response and this exposure to cigarette smoke may primarily affect the B cell function.

Differential requirement for accessory cells in polyclonal T-cell activation

Highly purified rat Ia-negative (OX-6-) and Ia-positive (OX-6+) T cells were employed to examine the requirement for accessory cells (AC) and/or soluble factors in the activation of resting T cells with Con A, PHA, sodium periodate, or antigen. A variety of cells were employed as AC, including Ia-positive and Ia-negative macrophages (M phi), gamma-irradiated (2000 rad) or non-irradiated OX-6+ T cells, and several Ia-negative adenovirus-transformed rat embryo fibroblast cell lines. Our results suggested that for the expression of IL-2 receptors (IL-2R) and proliferation of OX-6- T cells in response to Con A, PHA, or antigen, there was an obligatory requirement for the presence of AC which could not be overcome by the addition of IL-1 and/or IL-2. Activation of OX-6- T cells with antigen required the presence of Ia+ AC, while activation with mitogens could be initiated with Ia- AC. M phi were efficient in AC function in all responses tested, while the AC function of OX-6+ T cells (TAPC) proved discriminatory under different conditions. The optimal response to PHA required much higher concentrations of TAPC as AC than for the Con A response. TAPC failed to stimulate sodium periodate-treated T cells under any conditions tested. Furthermore, when TAPC were employed as AC, their antigen-presenting ability was radiosensitive, while their AC function for Con A and PHA was radioresistant. These results suggest that molecules involved in T cell-AC interactions may differ, depending on the source of AC and/or type of the proliferative stimulus provided to T cells. This data has been discussed in the context of T-cell activation.

Immune responsiveness of monkeys exposed chronically to cigarette smoke

Eleven adult male stumptailed monkeys (Macaca arctoides) were chronically exposed to either a low dose (human equivalent of 1 pack/day) or a high dose (human equivalent of 3 packs/day) of high-tar, high-nicotine University of Kentucky reference cigarette smoke for 4-8 years. Several parameters of their immunological response were compared to six nonsmoked control animals. The results from these experiments suggest that cigarette smoking does not significantly affect the response of spleen cells to the mitogens phytohemagglutinin or lipopolysaccharide. However, spleen cells from animals subjected to the heavy dose of cigarette smoke demonstrated a significant reduction in their natural killer cell-mediated lytic activity and a decreased response to concanavalin A. These results suggest that cigarette smoking may have a differential effect on lymphocyte subpopulations, and that the effects on the immune response are related to the dose of cigarette smoke.

Immunoregulation in the rat: characteristics of a suppressor T cell that inhibits antigen-dependent cell proliferation

We have examined the characteristics of a rat suppressor T cell (Ts) that inhibited the antigen-dependent proliferative response of antigen-primed T cells. The kinetics of in vitro induction of Ts from lymph node T cells obtained from antigen-primed rats indicated that Ts were induced in the presence of the priming antigen within 48 hr of culturing. The Ts produced during the first 48 hr of in vitro cultures were radiosensitive (2000 rad) but became partially radioresistant within the next 48 hr of culturing. In the presence but not the absence of priming antigen, Ts inhibited the antigen-dependent proliferative response to the priming antigen as well as to heterologous antigens. Suppression appeared to be mediated via a nondialyzable suppressor factor (TsF). The induction of Ts in cultures required the presence of OX-6-/OX-8- T cells, antigen-presenting cells, and the antigen. Although a majority of cells recovered from the induced cultures were OX-8+, there was no evidence that OX-8+ antigen expression per se was related to Ts activity. Addition of highly purified IL 2 augmented the Ts-mediated suppression. The immunoregulatory implications of these findings are discussed.

Immunoregulation in the rat: characteristics of a suppressor T cell that inhibits antigen-dependent cell proliferation

We have examined the characteristics of a rat suppressor T cell (Ts) that inhibited the antigen-dependent proliferative response of antigen-primed T cells. The kinetics of in vitro induction of Ts from lymph node T cells obtained from antigen-primed rats indicated that Ts were induced in the presence of the priming antigen within 48 hr of culturing. The Ts produced during the first 48 hr of in vitro cultures were radiosensitive (2000 rad) but became partially radioresistant within the next 48 hr of culturing. In the presence but not the absence of priming antigen, Ts inhibited the antigen-dependent proliferative response to the priming antigen as well as to heterologous antigens. Suppression appeared to be mediated via a nondialyzable suppressor factor (TsF). The induction of Ts in cultures required the presence of OX-6-/OX-8- T cells, antigen-presenting cells, and the antigen. Although a majority of cells recovered from the induced cultures were OX-8+, there was no evidence that OX-8+ antigen expression per se was related to Ts activity. Addition of highly purified IL 2 augmented the Ts-mediated suppression. The immunoregulatory implications of these findings are discussed.

Antigen presentation in the rat. II. An Ia+ radiosensitive T cell can present antigen to primed Ia- T cells

We demonstrated previously the presence of an Ia+ (OX-6+) antigen-presenting cell within the rat T cell fraction that is capable of presenting antigen to antigen-primed OX-6-T cells. This antigen-presenting cell (T-APC) reacted with the monoclonal antibodies W3/25 and W3/13, which is known to react mainly with rat T cells. Further characterization of the T-APC indicated that the cell also reacted with the monoclonal antibody OX-19, which is highly specific for rat T cells. Moreover, the antigen-presenting function of the T-APC was sensitive to treatment with mitomycin C or gamma-irradiation (2000 rad). Under similar conditions, antigen presentation by partially purified dendritic cells or macrophages was totally resistant to these treatments. The antigen-presenting activity of gamma-irradiated T-APC was not reconstituted by the addition of the lymphokines IL 1, IL 2, or Con A supernatants. Although unirradiated T-APC were able to stimulate an MLR response, this function was also sensitive to gamma-irradiation, whereas the MLR-stimulating ability of macrophages and dendritic cells was resistant to gamma-irradiation. These data indicate that Ia+ T cells from the rat are capable of presenting antigen to antigen-primed T lymphocytes and that, in contrast to antigen presentation by macrophages and dendritic cells, the function of T-APC is gamma-radiation sensitive.

Antigen presentation in the rat. II. An Ia+ radiosensitive T cell can present antigen to primed Ia- T cells

We demonstrated previously the presence of an Ia+ (OX-6+) antigen-presenting cell within the rat T cell fraction that is capable of presenting antigen to antigen-primed OX-6-T cells. This antigen-presenting cell (T-APC) reacted with the monoclonal antibodies W3/25 and W3/13, which is known to react mainly with rat T cells. Further characterization of the T-APC indicated that the cell also reacted with the monoclonal antibody OX-19, which is highly specific for rat T cells. Moreover, the antigen-presenting function of the T-APC was sensitive to treatment with mitomycin C or gamma-irradiation (2000 rad). Under similar conditions, antigen presentation by partially purified dendritic cells or macrophages was totally resistant to these treatments. The antigen-presenting activity of gamma-irradiated T-APC was not reconstituted by the addition of the lymphokines IL 1, IL 2, or Con A supernatants. Although unirradiated T-APC were able to stimulate an MLR response, this function was also sensitive to gamma-irradiation, whereas the MLR-stimulating ability of macrophages and dendritic cells was resistant to gamma-irradiation. These data indicate that Ia+ T cells from the rat are capable of presenting antigen to antigen-primed T lymphocytes and that, in contrast to antigen presentation by macrophages and dendritic cells, the function of T-APC is gamma-radiation sensitive.