Superfast nonlinear diffusion: capillary transport in particulate porous media.

The migration of liquids in porous media, such as sand, has been commonly considered at high saturation levels with liquid pathways at pore dimensions. In this Letter, we reveal a low saturation regime observed in our experiments with droplets of extremely low volatility liquids deposited on sand. In this regime, the liquid is mostly found within the grain surface roughness and in the capillary bridges formed at the contacts between the grains. The bridges act as variable-volume reservoirs and the flow is driven by the capillary pressure arising at the wetting front according to the roughness length scales. We propose that this migration (spreading) is the result of interplay between the bridge volume adjustment to this pressure distribution and viscous losses of a creeping flow within the roughness. The net macroscopic result is a special case of nonlinear diffusion described by a superfast diffusion equation for saturation with distinctive mathematical character. We obtain solutions to a moving boundary problem defined by superfast diffusion equation that robustly convey a time power law of spreading as seen in our experiments.

The association between cysteine, bone turnover, and low bone mass.

BACKGROUND: With the identification of hyperhomocysteinemia as a risk factor for developing osteoporosis, the contribution of thiols metabolically linked with homocysteine (tHcy) may be of importance. Cysteine (Cys) is formed from tHcy and is involved in bone metabolism via incorporation into collagen and cysteine protease enzymes. METHODS: We investigated the association of plasma Cys and related thiols, the bone turnover markers C-telopeptide (CTX) and procollagen type 1 N propeptide (P1NP) and folate and vitamin B(6) with calcaneal bone mineral density (BMD) in 328 postmenopausal British women grouped according to their BMD measurement. RESULTS: Subjects with low BMD had a significantly lower plasma Cys concentration (146.3 vs. 177.7 micromol/l, p < 0.0001), a significantly higher recent fracture rate (30.9% vs. 16.4%, p = 0.017), and a significantly higher percentage of current smokers (26.4% vs. 7.3%. p = 0.003) than those with normal BMD. Additionally, they had a significantly lower plasma Cys, and higher plasma tHcy and CTX, than those with osteopenia. In the whole population, Cys was significantly associated with BMD, weight, height, smoking habit, log creatinine, Cys-Gly, log tHcy, and log folate, but the significant positive association of Cys with BMD was maintained after correction for all other variables (r = 0.197, p = 0.003). After weight, Cys was the next most significant predictor of BMD in a stepwise multiple linear regression model. CONCLUSION: Our study suggests a significant association between plasma Cys and BMD. A reduced Cys concentration, possibly modulated by smoking, or reduced flux from tHcy, may lead to reduced availability for collagen formation. Increased osteoclast activation, possibly as a result of relative hyperhomocysteinemia, may lead to increased Cys utilization in cysteine proteases.

The association of homocysteine and its determinants MTHFR genotype, folate, vitamin B12 and vitamin B6 with bone mineral density in postmenopausal British women.

We studied the association between plasma total homocysteine (tHcy), its determinants folate, vitamin B(12), vitamin B(6) and MTHFR genotype, and bone mineral density (BMD) in 328 postmenopausal British women. When the subjects were assigned to one of 3 groups (control, osteopenic or osteoporotic) according to their BMD at the os calcis, those in the osteoporotic group had, compared with the controls, a significantly lower serum folate concentration, a significantly higher % of current smokers and a significantly higher incidence of recent fracture. In the population as a whole, we found significant associations of BMD with tHcy (r=-0.130, p=0.033, log tHcy) and folate (r=0.132, p=0.025, log folate). The association of folate with BMD was maintained after correction for age, weight and height (r=0.124, p=0.042, log folate), but the association of tHcy with BMD weakened after correction for age, weight, height and creatinine (r=-0.117, p=0.059, log tHcy). Vitamins B(12) and B(6) were not associated with BMD, but were significantly associated with tHcy, vitamin B(12) (r=-0.34, p<0.0001), vitamin B(6) (r=-0.16, p=0.007), as was folate (r=-0.41, p<0.0001). There was an increasing frequency of the MTHFR TT genotype across the 3 BMD groups, but this did not attain significance. Individuals with the TT genotype had significantly higher plasma tHcy but there was no difference between the genotypes (CC, CT, TT) for folate or BMD. Smoking was associated with a highly significant reduction in BMD and lower weight, and a significant reduction in circulating folate and vitamin B(6) concentrations, but no change in tHcy or vitamin B(12) concentrations when compared with non-smokers. We conclude that low serum folate is a significant risk factor for osteoporosis, with plasma tHcy having a lesser effect. Both vitamins B(12) and B(6), by acting through tHcy, may also have an effect on the skeleton, albeit a weaker one than folate. Cigarette smoking is a strong determinant of BMD, and may act through effects on folate and vitamin B(6).

Evaluation of a clinical screening instrument to identify states of thiamine deficiency in inpatients with severe alcohol dependence syndrome.

AIMS: To develop a Thiamine Deficiency Questionnaire (TDQ), and to assess its reliability in the identification of Thiamine deficiency, in patients with severe alcohol dependence. METHODS: 58 severely alcohol dependent patients underwent socio-demographic, medical, psychiatric, and alcohol use assessment, including administration of the Thiamine Deficiency Questionnaire (TDQ). The Red Blood Cell Thiamine Pyrophosphate concentration provided the 'gold standard' to test the validity of the instrument. Univariate 2 x 2 diagnostic test tables and multivariate analysis were performed. RESULTS: A set of eight questionnaire items had an overall predictive power of 73.7%. Two of these were highly specific: 'missed meals due to lack of funds', and the clinical co-occurrence of medical conditions potentially related to poor nutrition. The Michigan Alcohol Screening Test and serum gamma glutamyl transferase were moderately predictive. CONCLUSIONS: Screening that combines socio-demographic, clinical and biological factors, and/or standardized questionnaires, could improve early recognition of thiamine deficiency.

The management of gastric outlet obstruction secondary to inoperable cancer.

BACKGROUND: Historically, the distressing symptoms of malignant gastric outlet obstruction have been best managed by open gastrojejunostomy. We provide an assessment of an alternative laparoscopic technique. METHODS: We reviewed eight patients undergoing laparoscopic gastrojejunostomy. Patient data included age, sex, operation time, morbidity and mortality, length of stay, and outcome at 6 months where possible. RESULTS: There were six men and two women, their median age was 67 years. Median operating time was 135 min, median time to solid food was 4 days, and median postoperative stay was 7 days. Seven of our eight patients were palliated successfully using this technique. CONCLUSION: The risks inherent in operating on these patients, who are by definition in a poor state of health, has encouraged much interest in minimal access surgery. We conclude that laparoscopic gastrojejunostomy provides effective palliation of gastric outlet obstruction, and we recommend further evaluation of this technique.

Lack of effectiveness of short-term intravenous micronutrient nutrition in restoring plasma antioxidant status after surgery.

BACKGROUND AND AIMS: Many patients recovering from surgery may be in a state of negative antioxidant balance. For those whose postoperative nutritional requirements are provided intravenously, this may not be adequate for antioxidant repletion. This study was undertaken to assess the total antioxidant status of these patients peri-operatively and prior to beginning intravenous nutrition (IVN), and to determine the adequacy of IVN, including daily micronutrients, in maintaining or restoring antioxidant status in the post-operative period. METHODS: Plasma total antioxidant status (TAS) was measured in 30 patients who were fed by standard IVN following surgery. Additionally, the 'antioxidant gap' (AOG, a measure of the contribution of antioxidants other than albumin and urate) was calculated. Blood samples were taken on beginning IVN and daily for the duration of IVN, which lasted for up to 26 days. RESULTS: Prior to IVN, 20 of the 30 patients had a plasma TAS below the reference range and 15 of these 20 remained deficient even after IVN of up to 19 days. A further 3 patients became deficient whilst on IVN. When the group of patients who were deficient was compared with the group who were not, it was found that this difference was predominantly due to a difference in the AOG, (518 (115) v 709 (68) micromol/L (mean (SD)), P<0.0001). The groups did not differ in terms of age, C-reactive protein level, duration of IVN or daily thiol intake/Kg body weight. CONCLUSIONS: The difference in the gap antioxidants was thought to be due to their utilization in opposing the extra oxidative burden of surgery. Consideration of the antioxidant provision of standard IVN, principally the thiol-containing amino acids, ascorbate, alpha -tocopherol and trace elements suggests that this is insufficient to counter the sum of the pre-existing oxidative stress and the additional oxidative burden imposed by the surgery.

Spinal cord compression--a personal and palliative care perspective.

Malignant spinal cord compression is recognized as an oncological emergency. In spite of this, treatment in the U.K. varies widely from one area of the country to another. The reported survey shows that this variation is especially noticeable at weekends. Palliative care physicians and clinical nurse specialists working in the community are trained in the recognition of cord compression and are able to improve the early diagnosis and referral of these patients. In addition, they have an essential role in the follow-up of those who remain paraplegic.

Clinical-practice recommendations for the management of bowel obstruction in patients with end-stage cancer.

The paper highlights a series of questions that doctors need to consider when faced with end-stage cancer patients with bowel obstruction: Is the patient fit for surgery? Is there a place for stenting? Is it necessary to use a venting nasogastric tube (NGT) in inoperable patients? What drugs are indicated for symptom control, what is the proper route for their administration and which can be administered in association? When should a venting gastrostomy be considered? What is the role of total parenteral nutrition (TPN) and parenteral hydration (PH)? A working group was established to review issues relating to bowel obstruction in end-stage cancer and to make recommendations for management. A steering group was established by the (multidisciplinary) Board of Directors of the European Association for Palliative Care (EAPC) to select members of the expert panel, who were required to have specific clinical and research interests relating to the topic and to have published significant papers on advanced cancer patients in the last 5 years, or to have particular clinical expertise that is recognised internationally. The final constitution of this group was approved by the Board of the EAPC. This Working Group was made up of English, French and Italian physicians involved in the field of palliative care for advanced and terminal cancer patients; and of English, American and Italian surgeons who also specialized in artificial nutrition (Dr. Bozzetti) and a professor of health economics. We applied a systematic review methodology that showed the relative lack of RCTs in this area and the importance of retrospective and clinical reports from different authors in different countries. The brief was to review published data but also to provide clinical opinion where data were lacking. The recommendations reflect specialist clinical practice in the countries represented. Each member of the group was allocated a specific question and briefed to review the literature and produce a position paper on the indications, advantages and disadvantages of each symptomatic treatment. The position papers were circulated and then debated at a meeting held in Athens and attended by all panel members. The group reviewed all the available data, discussed the evidence and discussed what practical recommendations could be derived from it. An initial outline of the results of the review and recommendations was produced. Where there were gaps in the evidence, consensus was achieved by debate. Only unanimous conclusions have been incorporated. Subsequently the recommendations were drawn together by Carla Ripamonti (Chairperson) and Robert Twycross (Co-Chair) and refined with input from all panel members. The recommendations have been endorsed by the Board of Directors of the EAPC. It was concluded that surgery should not be undertaken routinely in patients with poor prognostic criteria, such as intra-abdominal carcinomatosis, poor performance status and massive ascites. A nasogastric tube should be used only as a temporary measure. Medical measures such as analgesics, anti-secretory drugs and anti-emetics should be used alone or in combination to relieve symptoms. A venting gastrostomy should be considered if drugs fail to reduce vomiting to an acceptable level. TPN should be considered only for patients who may die of starvation rather than from tumour spread. PH is sometimes indicated to correct nausea, whereas regular mouth care is the treatment of choice for dry mouth. A collaborative approach involving both surgeons and physicians can offer patients an individualized and appropriate symptom management plan.

Homocysteine and thiol metabolites in vitamin B12 deficiency.

Homocysteine metabolism is increasingly implicated in a diverse group of clinical disorders, including atheromatous vascular disease. We studied the disposition of homocysteine via the trans-sulphuration pathway, plasma glutathione peroxidase (GPx) activity and plasma levels of the sulphated hormone dehydro-epiandrosterone sulphate (DHEAS) in six vitamin B(12)-deficient human subjects before and after 2 weeks of vitamin B(12) repletion, both in the fasting state and following an oral methionine load (0.1 g/kg body weight). Fasting plasma total homocysteine concentrations fell (P=0.03) and total cysteine concentrations rose significantly (P=0.048) after treatment for 2 weeks with vitamin B(12) injections. The magnitude of the mean fall in the fasting concentration of homocysteine (38.8 micromol/l) was similar to the mean rise in cysteine levels (36.0 micromol/l) following vitamin B(12) therapy. Circulating levels of homocysteine were increased at 4 h after a methionine load when compared with fasting levels, both before and after vitamin B(12) repletion (P=0.003 for both). Total cysteinyl-glycine was lower post-methionine than in the fasting state following vitamin B(12) therapy (P=0.007). Fasting plasma GPx fell significantly after 2 weeks of vitamin B(12) therapy (P=0.05). The change in plasma GPx between the fasting state and 4 h after methionine loading was significantly different pre- and post-vitamin B(12) therapy (P=0.05). The present study provides indirect support to the hypothesis that defects in the trans-sulphuration and remethylation of homocysteine produce hyperhomocysteinaemia in vitamin B(12) deficiency in human subjects. Elevated homocysteine levels directly or indirectly may up-regulate GPx. Sulphation status, as measured by plasma DHEAS, was unchanged.

Symptom control in advanced gastrointestinal cancer.

Patients with advanced gastrointestinal cancer develop many symptoms as the disease progresses. However, the common problems of pain, nausea and vomiting, anorexia, constipation and intestinal obstruction can all be relieved by appropriate pharmacological treatment.

Interferon activation and innate immunity.

The interferons are a family of cytokine mediators critically involved in alerting the cellular immune system to viral infection of host cells. Interferons not only exhibit important antiviral effects but also exert a key influence on the quality of the cellular immune responses and amplify antigen presentation to specific T cells. Type I interferon (IFN-alpha and IFN-beta) is secreted by virus-infected cells while type II, immune or gamma interferon (IFN-gamma) is mainly secreted by T cells, natural killer (NK) cells and macrophages. Interferons interact with specific cellular receptors, which promote production of second messengers ultimately leading to expression of antiviral and immune modulatory genes. The IFN genes themselves are regulated by transcriptional and posttranscriptional mechanisms including modulation by a family of interferon regulatory factors (IRFs) synthesised by host cells. IFNs activate macrophages, induce B cells to switch immunoglobulin type, alter T helper response, inhibit cell growth, promote apoptosis and induce an antiviral state in uninfected cells. The therapeutic potential of the IFNs is currently the focus of intense attention in a number of virus-associated diseases, tumours and autoimmune disorders.

Expression of cathepsin S antisense transcripts by adenovirus in retinal pigment epithelial cells.

PURPOSE: To show the production of sense or antisense transcripts by recombinant adenoviruses, to investigate whether the transcripts produced were suitable for downregulating the expression of the targeted gene, cathepsin S (CatS), and to examine the effect of antisense transcript production on the biologic function of retinal pigment epithelial (RPE) cells, including the regulation of endogenous aspartic protease expression. METHODS: Ad.MLP.CatSAS, Ad.RSV.CatSAS, and Ad.MLP.CatSS recombinant viruses were produced by homologous recombination. The recombinant viruses were tested by restriction enzyme digestion to confirm the orientation of the inserts. The expression of antisense transcripts was tested by northern blot analysis. Western blot analysis was used to study the regulation of the endogenous CatS protein in ARPE19 cells. The biologic effect of CatS downregulation in ARPE19 cells was tested by proliferation and phagocytosis assays, de novo cathepsin D (CatD) synthesis, and measurement of aspartic protease activity. RESULTS: After characterization of the recombinant adenovirus constructs, the production of antisense and sense CatS transcripts was shown in ARPE19 cells. The transcripts appeared at approximately 1.9 kb 48 hours after transduction, and the expression of the antisense transcripts was similar in constructs carrying either the MLP or the RSV promoter. Western blot analysis showed that ARPE19 cells transduced with Ad.MLP.CatSAS and Ad.RSV.CatSAS had no detectable CatS. In contrast, there was a strong signal appearing at 24 kDa in ARPE19 cells transduced with Ad.MLP.CatSS. ARPE19 cells were transduced to a high level. The transduction of ARPE19 cells with the recombinant adenoviruses did not affect the morphologic appearance of the cells, their proliferation, or their phagocytosing ability. However, ARPE19 cells transduced by Ad.MLP.CatSAS recombinant adenovirus showed a significant downregulation of de novo CatD synthesis and a twofold decrease in aspartic protease activity. CONCLUSIONS: Recombinant adenoviruses were shown to be suitable for producing antisense CatS transcripts to modulate endogenous CatS expression in RPE cells. It is proposed that CatS may play an important role, directly or indirectly, in the lysosomal digestion of outer segments through the regulation of other lysosomal enzyme activity, such as the expression of CatD.

Does total antioxidant status relate to outcome in very preterm infants?

1. In healthy humans, a balance exists between oxygen-derived free-radical production and their removal by antioxidants. In preterm infants inadequate antioxidant defences may contribute to the pathogenesis of some of the complications of prematurity. 2. Plasma total antioxidant status and malondialdehyde concentration were measured during the first 11 days of life in 25 infants to determine whether increased lipid peroxidation is associated with low extracellular antioxidant status. In a second group of infants, total antioxidant status was quantified within 12 h of birth, and subsequently on days 4 and 10 to investigate the hypothesis that adverse neonatal outcome is associated with low antioxidant status. 3. There may be a weak negative correlation between the total antioxidant status of infants and the lipid peroxidation marker malondialdehyde in plasma (r = -0.24, P = 0.056, n = 89) during the first 11 days of life. In the second group of infants, total antioxidant status was found to be significantly related to plasma urate and bilirubin levels, but not to adverse neonatal outcomes such as chronic lung disease, intraventricular haemorrhage, retinopathy of prematurity or death. 4. If adverse neonatal outcomes are due to inadequate antioxidant defences, these are likely to be intracellular or localized rather than general extracellular deficiencies.

Role of interferon-gamma in the priming of decidual macrophages for nitric oxide production and early pregnancy loss.

We have previously shown that both priming and triggering signals were needed for nitric oxide production by decidual macrophages and that nitric oxide was responsible for embryo wastage. In this study, we investigated the role of IFN-gamma as the primary signal for macrophage activation in early embryo loss. IFN-gamma-deficient (GKO) and heterozygous F1 control mice were injected with lipopolysaccharide (LPS) at day 7 of gestation. The results showed that the GKO mice were more resistant to LPS-induced embryo loss than the wild type. This suggested that IFN-gamma was needed for LPS-induced embryo resorption and that decidual macrophages from pregnant GKO mice were not primed and could not be activated when given LPS. Further, the results showed that IFN-gamma mRNA was simultaneously expressed in the same embryos that also expressed mRNA markers for macrophage activation (TNF-alpha and iNOS), indicating that macrophage activation could be a consequence of IFN-gamma production. Similarly, we investigated the role of IL-12 as a switch cytokine capable of eliciting TH1-associated cytokine production including IFN-gamma. The results showed that IL-12 mRNA expression was correlated with IFN-gamma expression and macrophage activation. In this in vivo study, we showed for the first time that spontaneously increased decidual IFN-gamma expression is detrimental to embryo survival.

Modulation of cathepsin D activity in retinal pigment epithelial cells.

This project used retinal pigment epithelial (RPE) cells to investigate the effects of up- and down-regulation of cathepsin D expression on the processing of cathepsin D and on the normal phagocytic and digestive function of these cells. RPE cells were transfected with a pHbetaApr-1-neo vector construct carrying the full-length sequence of the translated region of human cathepsin D in sense and antisense directions. Transfected cells were characterized for the presence and expression of the transgene by PCR amplification using transgene-specific primers. Total aspartic proteinase activity present in transformed RPE cells was measured by an enzyme assay using haemoglobin as substrate. Flow cytometry was used to quantify phagocytosis of fluorescein isothiocyanate-labelled rod outer segments (ROS), and lysosomal digestion of ROS was monitored by immunofluorescence. A 435 bp fragment was present in RPE cells carrying the cathepsin D transgene in sense and antisense orientations after PCR amplification. Expression of both 52 kDa procathepsin D and 34 kDa active cathepsin D was significantly up-regulated in sense cathepsin D-transfected RPE cells and down-regulated in RPE cells transfected with antisense cathepsin D. No other forms of cathepsin D were detected in the transfected cells, suggesting that, if pseudo-cathepsin D exists in RPE cells in vivo, it requires the presence of unknown specific regulatory elements. The up- and down-regulation of cathepsin D expression was further confirmed by enzyme assay. Transfected cells retained their phagocytosing ability after ROS challenge and maintained their ability to process ROS. The processing of ROS was significantly slower in RPE cells transfected with antisense than control vector or in sense-cathepsin D-transfected cells. These results demonstrate that cathepsin D is a major proteolytic enzyme participating in the lysosomal digestion of photoreceptor outer segments.

Decidual infiltration and activation of macrophages leads to early embryo loss.

PROBLEM: There is considerable controversy concerning the root cause and mechanisms of early embryo loss. It has been suggested that most pregnancy losses occur due to morphogenetic anomalies of the embryo. It has also been suggested that the maternal specific immune system rejects the embryo. METHODS: Existing data on the cell and molecular biology of early embryo loss in murine experimental models is reviewed. RESULTS: Using the CBA(female) x DBA/2(male) model of early embryo loss, it has been established that maternal inflammatory cells infiltrate the decidua basalis of all implantation sites within 48 hr after implantation. For most embryos, the relatively low numbers of macrophages (Mphi) and natural killer-like (NK-like) cells of maternal origin remain relatively constant after day 8, whereas 20-30% of the embryos show a significant increase in inflammatory cells in the maternal decidua, corresponding to the incidence of early embryo resorption visible at day 12. Evidence will be reviewed to suggest that decidual NK-like cells are not cytolytic but may be producing the Mphi-activating cytokine interferon gamma (IFN-gamma), which activates decidual Mphi and other cells. Furthermore, embryo loss is ameliorated by in vivo treatment with anti-IFNgamma or anti-NK antisera, indicating that NK-like cells and/or IFNgamma are required for embryo loss, but not for embryo survival. In resorbing embryos, the inflammatory Mphi show evidence of having been primed during early pregnancy, in that in vitro incubation with lipopolysaccharide induced the production of tumor necrosis factor alpha and nitric oxide. CONCLUSION: These findings support the concept that early embryo loss is a nonspecific event mediated by the triggering of cytotoxin production by primed decidual macrophages.

Early embryo loss is associated with the prior expression of macrophage activation markers in the decidua.

In early embryo loss, the activation of maternal immune effector mechanisms play a critical role in determining the success or failure of a pregnancy. We have previously shown that increased nitric oxide production by decidual macrophages is involved in early embryo loss occurring at day 12 of gestation. In this study, using reverse transcription-PCR and Southern blotting, the expression of inducible nitric oxide synthases (iNOS) and TNF-alpha mRNA was determined to quantify macrophage activation in individual murine embryos in a model of spontaneous early embryo loss. At day 8 of gestation, 32 and 29% of embryos with no apparent pathology showed an increase in iNOS and TNF-alpha mRNA expression, respectively. This corresponds to the natural resorption rate seen in the mouse model. In addition, the percentage of embryos with increased iNOS and TNF-alpha mRNA expression was further augmented when pregnant mice were induced to abort at a higher rate. These results showed, for the first time, a correlation between increased iNOS and TNF-alpha expression and embryo resorption. The results provide evidence for the presence of activated macrophages at implantation sites before overt embryo damage occurs.