Hepatic gene expression of apolipoprotein B100 during early lactation in underfed, high producing dairy cows

The hepatic gene expression of apolipoprotein B, the major protein of very low density lipoproteins in plasma, was studied using 8 Holstein x Friesian cows during the first 12 wk of lactation. Cows were fattened during gestation and were underfed just after parturition to increase fat mobilization and subsequent hepatic steatosis. Intracellular concentrations of apolipoprotein B and apolipoprotein B mRNA and control parameters (albumin, total lipids, RNA, and proteins) were determined in liver samples obtained by biopsy from each cow on four occasions at 1, 2, 4, and 12 wk after calving. Results were compared with those obtained from 5 dry cows in late pregnancy and 4 dry nonpregnant cows. The hepatic concentration of apolipoprotein B was lower (approximately 25%) during wk 1, 2, and 4 after calving, a period of intense liver steatosis (44.2 to 95.7 mg of triglycerides/g of fresh tissue), than for nonsteatotic dry cows (pregnant or nonpregnant); hepatic concentrations were also lower than those during wk 12. In contrast, hepatic concentrations of mRNA coding for apolipoprotein B, total proteins, RNA, and albumin did not vary significantly during early lactation. These results suggested that synthesis of apolipoprotein B during early lactation is specifically regulated at a posttranscriptional level by a decrease in the rate of translation, or by a higher rate of intracellular degradation of apolipoprotein B, or both.

Season of birth: aetiological implications for epilepsy

In most cases of epilepsy it is not possible to reach an aetiological diagnosis. Recent research points to a pre-perinatal disruption of the neurodevelopment as being the cause of at least some of these epilepsies of unknown aetiology. The object of this study was to corroborate this hypothesis from an epidemiological perspective and identify the most likely candidates for causes of this damage. The approach used was an analysis of the seasonal pattern of births in a large sample of epileptic patients discharged from NHS hospitals in England and Wales. The results illustrated that the seasonality of the births in the epileptic sample was significantly different from that of the general population, with an excess of patients born in December and January and a deficit of those born in September. This "seasonality' was present only in the patients born before the late 1950s. These results are suggestive of the existence of an aetiological factor for epilepsy with a seasonal presence in the environment and which is epileptogenic when acting in the pre-perinatal period. Prenatal infections, obstetric complications and nutrititional deficiencies are amongst the hypotheses developed on the nature of this agent(s).

Strength in the lower limbs, visual contrast sensitivity, and simple reaction time predict cognition in older women

The authors investigated the association between sensorimotor variables indicative of biological aging and cognition. A community sample of 202 women ages 60-86 was assessed on 5 measures of lower limb strength, visual contrast sensitivity (VisCS), and reaction time (RT). Hierarchical multiple regression revealed that the sensorimotor variables explained age-related variance in measures of reasoning and total variance in measures of reasoning after education, health, mood, and physical activity were controlled for. It is concluded that in addition to better known predictors of cognitive aging, such as RT and VisCS, lower limb strength is an important predictor of performance on cognitive tests.

Characterization of renal ischemia-reperfusion injury in rats

The purpose of this study was to characterize the time course of renal ischemia-reperfusion injury in the rat. Male Sprague-Dawley rats were subjected to bilateral renal clamping for 45 min. At reestablishment of blood flow, the rats were divided into nine groups (representing 0, 0.5, 1, 2, 4, 6, 9, and 24 h, and 1 week post-ischemia). At each time point, blood samples were taken for analysis of blood urea nitrogen (BUN) and creatinine, and both kidneys were harvested for histopathology and myeloperoxidase activity (MPO) assays. An intracellular adhesion molecular (ICAM-1) monoclonal antibody (IMAb) was tested in a separate group of animals (1 mg/rat) to confirm that it may provide renal protection previously reported by Kelly et al. (1994). Following renal ischemia, significant increases in serum BUN and creatinine were observed compared to levels in normal animals. Serum BUN and creatinine increased 2, 4, and 6 h post-ischemia leading to peak elevations 24 h post-ischemia. Values returned to normal at the 1 week time point. MPO activity was slightly increased 2 and 4 h following ischemia, with peak elevations occurring at the 6-h and 9-h time points. Histopathologic examination of kidneys revealed that the most severe damage occurred at the 24-h time point, which correlated with the peak elevations in serum BUN and creatinine. Evidence of renal injury was still evident histologically 1 week following ischemia, although renal function tests (BUN and creatinine) had returned to normal. In summary, renal injury following ischemia may be demonstrated as early as 4 h post-ischemia as judged by changes in renal function, MPO levels, and renal histopathology. However, based upon renal function tests and histology, peak injury is observed approximately 24 h following ischemia. The ICAM-1 monoclonal antibody, ICAM-Ab, provided some renal protection against ischemia-reperfusion injury in this study as measured by serum creatinine, BUN and renal histopathology. However, in contrast to the results reported by Kelly et al., the magnitude of the protective effects was not as dramatic in the present study, and furthermore, no reductions in renal MPO activity were observed.

Effects of group exercise on cognitive functioning and mood in older women

A randomised controlled trial was conducted to determine whether a 12-month program of group exercise had beneficial effects on physiological and cognitive functioning and mood in 187 older community-dwelling women. The exercisers (n = 94) and controls (n = 93) were well matched in terms of the test measures and a number of health and life-style assessments. The mean number of classes attended by the 71 exercise subjects who completed the program was 59.0 (range 26 to 82). At the end of the trial, the exercisers showed significant improvements in reaction time, strength, memory span and measures of wellbeing when compared with the controls. There was also an indication that anxiety had been reduced in the exercisers. Within the exercise group, improvements in memory span were associated with concomitant improvements in both reaction time and muscle strength. Also, within this group, initial mood measures were significantly inversely associated with improvements at retest, which suggests that the program may have normalised mood states in subjects who had high initial depression, anxiety and stress levels, rather than inducing improvements in all subjects. These findings suggest that group exercise has beneficial effects on physiological and cognitive functioning and wellbeing in older people.

Dissection of the promoter/operator region and evaluation of N-acylhomoserine lactone mediated transcriptional regulation of elastase expression in Pseudomonas aeruginosa

In Pseudomonas aeruginosa, expression of the lasB gene which codes for the metalloprotease, elastase, depends on small diffusible N-acylhomoserine lactones. lasB expression is regulated through the interactions of N-3-oxododecanoyl-L-homoserine lactone and N-butanoyl-L-homoserine lactone with the transcriptional activators LasR and VsmR(RhlR), respectively. To investigate lasB expression further, we first located the transcriptional start site to a position 141 bp upstream from the translational start site. Using this information, we constructed a series of plasmids containing consecutive 5' deletions of the upstream region of lasB fused to a promoterless chloramphenicol acetyltransferase reporter gene. The results obtained indicate that three regions are required for efficient transcription of lasB; a 35 bp palindromic sequence located at +26 to +60 bp upstream from the translation start site, and two regions located upstream of the transcription start site, at -135 to -85 bp and -63 to -26 bp, respectively. Deletion of the latter region results in the loss of both N-butanoyl-L-homoserine lactone- and N-3-oxododecanoyl-L-homoserine lactone-mediated stimulation of lasB expression and provides further support for the role of this operator site as a target for either or both LasR and VsmR.

Rhamnogalacturonan II, a dominant polysaccharide in juices produced by enzymic liquefaction of fruits and vegetables

Rhamnogalacturonan II (RG-II), a small complex pectic polysaccharide, is released from apple (Malus domestica), carrot (Daucus carota), and tomato (Solanum lycopersicum) by treatment with two commercial liquefying enzyme preparations. RG-II was isolated by size-exclusion chromatography from apple, tomato, and carrot juices obtained by enzymic liquefaction. All the RG-IIs contained the diagnostic sugars, apiose, 2-O-methyl-L-fucose, 2-O-methyl-D-xylose, aceric acid, Kdo and Dha. Glycosyl-linkage compositions of the neutral and acidic sugars, including aceric acid, were consistent with the hypothetical model described for sycamore RG-II confirming the conservation of RG-II in plants. Thus, when pectinolytic enzyme preparations are used to process fruits and vegetables, RG-II is released as a main soluble polysaccharide fraction while other pectic polysaccharides are heavily degraded.

BIA/MS: interfacing biomolecular interaction analysis with mass spectrometry

Biomolecular interaction analysis (BIA) which utilizes surface plasmon resonance (SPR) detection of affinity-captured analytes has been interfaced with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI). Femtomole quantities of a peptide, myotoxin a, were detected by direct MALDI analysis of sensor chips used during BIA of a polyclonal anti-myotoxin a IgG/myotoxin a system. Further, different interactive surfaces (flow cells) present on a single biosensor were targeted individually for mass spectrometric analysis. System compatibility of the combined approach was demonstrated with sensitivities, detection limits, and analytical performances comparable to those intrinsic to the individual analyses. The combined approach unites the real-time capabilities of SPR-based BIA with the qualitative specificity of mass spectrometry.

A comparison of two Brazilian populations of Culex quinquefasciatus (Say, 1823) from endemic and non-endemic areas to infection with Wuchereria bancrofti (Cobbold, 1877)

Culex quinquefasciatus is known to be an efficient insect host of Wuchereria bancrofti. In Brazil Cx. quinquefasciatus is widely distributed throughout the country and is often abundant in and around human habitations. In contrast, Bancroftian filariasis is limited to three foci in Brazil. Experiments were undertaken to compare the vector capacities of Cx. quinquefasciatus originating from Maceió (Alagoas), one of the endemic areas of W. bancrofti infection in Brazil, and Belo Horizonte (Minas Gerais), a non endemic area. Laboratory-reared Cx. quinquefasciatus were dissected 20 days after blood feeding on microfilaraemic patients. Survival rates and the number of infective larvae that developed did not differ in female mosquitoes of different origins. Thus both populations of Culex were susceptible to infection with W. bancrofti.

The role of automated peritoneal dialysis (APD) in an integrated dialysis programme

While there is no doubt that renal transplantation would be the preferred option for all patients suffering from end stage renal disease, this is sadly an unrealistic aim for many patients in the UK. There is a shortage of donor organs and, with the increasing percentage of elderly patients on dialysis, under 50% of all dialysis patients are on the national transplant waiting list. Of the 12,000 or so patients on dialysis in the UK, approximately half receive haemodialysis and half peritoneal dialysis. In the last few years, there has been a resurgence of interest in automated peritoneal dialysis and just under 20% of the peritoneal dialysis population currently receive this mode of therapy. The advantages of automated peritoneal dialysis include the capacity for an increased dialysis prescription, increased freedom and quality of life and a decreased risk of peritonitis and intra peritoneal pressure related problems. These advantages may offset the increased cost of automated peritoneal dialysis and long-term patient morbidity and mortality may be diminished by its provision in an integrated dialysis programme.

Spirometry values in stable lung transplant recipients

To clarify the usefulness of spirometry to assess the function of the lung allograft post-transplant, we retrospectively reviewed 351 sequential spirometry measurements performed by 65 healthy recipients after the 80th postoperative day when the clinical evaluation and fiberoptic bronchoscopy with transbronchial biopsies and bronchoalveolar lavage excluded significant rejection or infection in the allograft. The mean coefficients of variation (CV) and significant values for change (SC) for the FVC, FEV1, and FEF25-75% were calculated according to the type of transplant procedure (heart-lung and double-lung [HL-DL] versus single-lung [SL]), and to the time after transplant when the spirometry measurements were obtained < or = 1 yr versus > 1 yr). The SC for the FVC decreased with time after transplantation for both HL-DL (< or = 1 yr: 17% versus > 1 yr: 7%) and SL recipients (< or = 1 yr: 13% versus > 1 yr: 8%). The higher degree of variability within the first year was primarily due to increasing values especially in the HL-DL recipients. The SC for the FEV1 also decreased over time for HL-DL recipients (< or = 1 yr: 18% versus > 1 yr: 9%) but was similar for SL recipients at both intervals (13%). Our results suggest that decreases of > or = 11% in FVC or 12% in FEV1 in HL-DL recipients and > or = 12% in FVC or 13% in FEV1 for SL recipients indicate a significant decrease in allograft function that may be due to infection or rejection.

High-resolution MR of the intraparotid facial nerve and parotid duct

PURPOSE

To describe a high-resolution MR imaging technique that depicts the complex anatomy of the region of the parotid gland, focusing on the intraparotid components of the facial nerve and parotid duct.

METHODS

High-resolution T1-weighted images of the parotid gland were acquired with a prototype three-dimensional Fourier transform gradient-echo sequence that permits a very short echo time (4.2 milliseconds) by using a modified phase-encoded time-reduced acquisition scheme. The sequences were obtained at 1.5 T with a head and neck coil. Postprocessed multiplanar, curved and volumetric images were obtained. The most clinically useful images were acquired at parameters of 40/4.2 (TR/TEeff) a flip of 30 degrees, a field of view of 18 to 20 cm, a matrix of 512 x 288 or 512 x 256, an axial plane, 60 images, no gaps, and a section thickness of 1.5 mm. Eighteen healthy subjects were examined. The position of the facial nerve within the parotid gland was determined by identifying the facial nerve in the stylomastoid foramen and then following it on sequential sections through the parotid gland. Curved reformations were used to confirm the visibility of the nerve. A similar technique was used for the parotid duct.

RESULTS

The image contrast obtained was similar to that of standard spin-echo T1-weighted images. The parotid gland showed intermediate signal intensity while the fat spaces showed high signal intensity. The vessels had variable signal intensity depending on saturation. The cerebrospinal fluid, nerves, muscles, and ducts had lower signal intensity. In all 18 subjects, the facial nerve from the brain stem to the parotid gland, and the parotid duct from the mouth to the hilus of the gland were seen bilaterally. The proximal intraparotid facial nerve to the level of the retromandibular vein was seen in 72% of the subjects and the main intraparotid ducts were seen in 66% of the subjects.

CONCLUSION

High-resolution MR imaging offers simultaneous display of most of the important structures in the region of the parotid gland, including the intraparotid duct and facial nerve.

Design of multiple binary outcome studies with intentionally missing data

We discuss the design and analysis of studies involving multiple binary outcomes in which only a subset of these outcomes can be measured on each individual. Such studies with "intentionally missing data" may arise due to practical or economic constraints; several examples from toxicology serve as illustrations. A global test statistic based on generalized estimating equations is presented and evaluated under a variety of missing patterns and correlation structures. Extensions of the global test statistic to allow for clustered data are also described. The relative efficiency of the global test statistic with missing data relative to that for complete data is investigated, both under a common dose effect alternative and when exposure has differential effects on the multiple endpoints. The implications of these efficiency calculations on study design are explored, and several recommendations are provided.

Conservation and antigenic cross-reactivity of the transferrin-binding proteins of Haemophilus influenzae, Actinobacillus pleuropneumoniae and Neisseria meningitidis

Haemophilus influenzae acquires iron from the iron-transporting glycoprotein transferrin via a receptor-mediated process. This involves two outer-membrane transferrin-binding proteins (Tbps) termed Tbp1 and Tbp2 which show considerable preference for the human form of transferrin. Since the Tbps are attracting considerable attention as potential vaccine components, we used transferrin affinity chromatography to examine their conservation amongst 28 H. influenzae type b strains belonging to different outer-membrane-protein subtypes as well as six non-typable strains. Whole cells of all type b and non-typable strains examined bound human transferrin; whilst most strains possessed a Tbp1 of approximately 105 kDa, the molecular mass of Tbp2 varied from 79 to 94 kDa. Antisera raised against affinity-purified native H. influenzae Tbp1/Tbp2 receptor complex cross-reacted on Western blots with the respective Tbps of all the Haemophilus strains examined. When used to probe Neisseria meningitidis Tbps, sera from each of four mice immunized with the Haemophilus Tbp1/2 complex recognized the 68 kDa Tbp2 of N. meningitidis strain B16B6 but not the 78 kDa Tbp2 of N. meningitidis strain 70942. Serum from one mouse also reacted weakly with Tbp1 of strain B16B6. Apart from a weak reaction with the Tbp2 of a serotype 5 strain, this mouse antiserum failed to recognize the Tbps of the porcine pathogen A. pleuropneumoniae. However, a monospecific polyclonal antiserum raised against the denatured Tbp2 of Neisseria meningitidis B16B6 recognized the Tbps of all Haemophilus and Actinobacillus strains examined. Since H. influenzae forms part of the natural flora of the upper respiratory tract, human sera were screened for the presence of antibodies to the Tbps. Sera from healthy adults contained antibodies which recognized both Tbp1 and Tbp2 from H. influenzae but not N. meningitidis. Convalescent sera from meningococcal meningitis patients contained antibodies which, on Western blots, recognized the Tbps2s of both pathogens. These data demonstrate the existence of shared epitopes on the Tbps of H. influenzae, N. meningitidis and A. pleuropneumoniae despite their transferrin species specificity.

Analysis of bacterial carbapenem antibiotic production genes reveals a novel beta-lactam biosynthesis pathway

Carbapenems are beta-lactam antibiotics which have an increasing utility in chemotherapy, particularly for nosocomial, multidrug-resistant infections. Strain GS101 of the bacterial phytopathogen, Erwinia carotovora, makes the simple beta-lactam antibiotic, 1-carbapen-2-em-3-carboxylic acid. We have mapped and sequenced the Erwinia genes encoding carbapenem production and have cloned these genes into Escherichia coli where we have reconstituted, for the first time, functional expression of the beta-lactam in a heterologous host. The carbapenem synthesis gene products are unrelated to enzymes involved in the synthesis of the so-called sulphur-containing beta-lactams, namely penicillins, cephamycins and cephalosporins. However, two of the carbapenem biosynthesis genes, carA and carC, encode proteins which show significant homology with proteins encoded by the Streptomyces clavuligerus gene cluster responsible for the production of the beta-lactamase inhibitor, clavulanic acid. These homologies, and some similarities in genetic organization between the clusters, suggest an evolutionary relatedness between some of the genes encoding production of the antibiotic and the beta-lactamase inhibitor. Our observation are consistent with the evolution of a second major biosynthetic route to the production of beta-lactam-ring-containing antibiotics.

Predictors of adherence to a structured exercise program for older women

This study examined whether psychological, physiological, and health and lifestyle measures were associated with adherence to a structured exercise program for older women. Women aged "60 to 85 years (N = 102)," randomly recruited from the community, were assessed on these measures before and after a 12-month exercise trial. Sixty-nine women completed the trial, and 54 continued participation after the trial for at least 6 months. Adherence was examined at various stages during the trial. Multiple regression analysis revealed that reduced muscle strength, slow reaction time, and psychoactive drug use explained most of the variance in adherence during the trial. In contrast, muscle strength, reasoning ability, depression, and self-reported improvement in strength best predicted continued participation after the trial. The findings have implications for community-based exercise programs and research trials.

Identification of a novel bone/calcium metabolism-regulating factor in porcine pancreas

We purified from porcine pancreas a hypocalcemic peptide clearly distinguishable from other pancreatic osteotropic factors such as amylin, calcitonin, and glucagon. Porcine pancreas was processed by acetone extraction, anion exchange chromatography, isoelectric focusing, and reverse-phase high performance liquid chromatography. Fractions were assayed for their inhibitory effects on bone resorption in vitro. Amino acid sequence of a homogeneous 28-kDa protein revealed 92% homology to a human elastase IIIB in the N terminus. Recombinant human elastase IIIB (rhEIIIB) inhibited bone resorption in organ culture stimulated by 1,25-dihydroxyvitamin D3 at concentrations as low as 75 ng/ml. Antibodies to rhEIIIB recognized purified pancreatic factor in Western blots and blocked its inhibitory effect on bone resorption. This antiresorptive activity was abolished by phenylmethylsulfonyl fluoride, suggesting the importance of elastase proteolytic activity for inhibition of bone resorption. In vivo, rhEIIIB and purified pancreatic factor significantly decreased recombinant human interleukin-1alpha-induced hypercalcemia. In conclusion, a novel naturally occurring inhibitor of bone resorption and calcium-lowering peptide has been identified in porcine pancreas. Because this pancreatic peptide has systemic effects on bone resorption and blood ionized calcium at low concentrations, it may represent a physiological regulator of normal bone remodeling and calcium homeostasis.

Structural characterization of red wine rhamnogalacturonan II

The pectic polysaccharide rhamnogalacturonan II (RG-II), which accounts for approximately 20% of the ethanol-precipitable polysaccharides in red wine, has been isolated from wine polysaccharides by anion-exchange chromatography. Four fractions enriched with RG-II were obtained and the RG-II then purified to homogeneity by Concanavalin A affinity and size-exclusion chromatographies. The glycosyl-residue compositions of the four RG-IIs are similar; all the RG-IIs contain the monosaccharides (apiose, 2-O-methyl-L-fucose, 2-O-methyl-D-xylose, Kdo, Dha, and aceric acid) that are diagnostic of RG-II. The glycosyl-linkages of the neutral and acidic sugars, including aceric acid, were determined simultaneously by GC-EIMS analysis of the methylated alditol acetates generated from per-O-methylated and carboxyl-reduced RG-II. Two of the RG-IIs contain boron, most likely as a borate di-ester that cross-links two molecules of RG-II together to form a dimer. The dimer contains 3'- and 2,3,3'-linked apiosyl residues whereas the monomer contains only 3'-linked apiosyl residues which suggests that the borate di-ester is located on at least one of the apiosyl residues of RG-II. Although the wine RG-IIs all have similar structures they are not identical since they differ in the length and degree of methyl-esterification of the RG-II backbone and in the presence or absence of borate di-esters. Nevertheless, these studies show that the major structural features of wine and primary cell wall RG-II are conserved.

Purification and characterization of LasR as a DNA-binding protein

In Pseudomonas aeruginosa, the activator protein LasR and a cognate autoinducer (AI) are required for expression of the elastase gene (lasB). In the present study, we investigated the binding properties of the P. aeruginosa lasR gene product. The LasR protein was overexpressed and purified as a glutathione S-transferase (GST) fusion protein. Using gel retardation and UV cross-linking analysis, we demonstrated that the GST-LasR could bind to a separate site in the lasB upstream operator regions 1 and 3 in the presence of the autoinducer. Regions 1 and 3 are located at 105 and 42 base pairs upstream, respectively, from the lasB transcriptional start site. Our present results clearly demonstrate that LasR is a specific DNA-binding protein that regulates the transcription of the lasB gene in the presence of an autoinducer.

A hierarchical quorum-sensing cascade in Pseudomonas aeruginosa links the transcriptional activators LasR and RhIR (VsmR) to expression of the stationary-phase sigma factor RpoS

In Pseudomonas aeruginosa, the production of many virulence factors and secondary metabolites is regulated in concert with cell density through quorum sensing. Two quorum-sensing regulons have been identified in which the LuxR homologues LasR and RhlR are activated by N-(3-oxododecanoyl)-L-homoserine lactone (OdDHL) and N-butanoyl-L-homoserine lactone (BHL) respectively. The lasR and rhlR genes are linked to the luxl homologues lasl and rhll, which are responsible for synthesis of OdDHL and BHL, respectively. As lasRl and rhlRl are both involved in regulating synthesis of exoenzymes such as elastase, we sought to determine the nature of their interrelationship. By using lacZ transcriptional fusions in both homologous (P. aeruginosa) and heterologous (Escherichia coli) genetic backgrounds we provide evidence that (i) lasR is expressed constitutively throughout the growth cycle, (ii) rhlR expression is regulated by LasR/OdDHL, and (iii) that RhlR/BHL regulates rhll. We also show that expression of the stationary-phase sigma factor gene rpoS is abolished in a P. aeruginosa lasR mutant and in the pleiotropic BHL-negative mutant PANO67. Furthermore, our data reveal that kin E. coli, an rpoS-lacZ fusion is regulated directly by RhlR/BHL. Taken together, these results indicate that P. aeruginosa employs a multilayered hierarchical quorum-sensing cascade involving RhlR/BHL and LasR/OdDHL, interlinked via RpoS, to integrate the regulation of virulence determinants and secondary metabolites with adaptation and survival in the stationary phase.