Immobilization of microorganisms by adhesion: interplay of electrostatic and nonelectrostatic interactions

The adhesion of three microorganisms (Saccharomyces cerevisiae, Acetobacter aceti, and Moniliella pollinis) to different materials has been studied using various supports (glass, metals, plastics), some of which were treated by an Fe(III) solution. The surface properties of the cells were characterized by the zeta potential and an index of hydrophobicity; characterization of the supports involved surface chemical analysis (XPS) and contact angle measurements. Cell suspensions in pure water at a given pH were left to settle on plates; the latter were then rinsed and examined microscopically, Saccharomyces cerevisiae and A. aceti adhere to metals under certain pH conditions but do not adhere to any of the other materials tested unless it is previously treated by ferric ions; adhesion of these hydrophilic cells is essentially controlled by electrostatic interactions. Moniliella pollinis adhere spontaneously to glass and to polymeric materials, but its attachment is also influenced by cell-cell or cell-support electrostatic repulsions; near the cell isoelectric point, cell flocculation is competing with adhesion to a support.

The association between polycystic ovaries and endometrial cancer

BACKGROUND

Women with polycystic ovary syndrome (PCOS) are assumed to be at increased risk of endometrial cancer (EC), albeit of a more differentiated type with better prognosis than in normal women. This study was designed to test these assumptions, as evidence for them is lacking.

METHODS

The prevalence of polycystic ovaries (PCO), as a marker of PCOS, was investigated in ovarian sections from 128 women with EC and 83 with benign gynaecological conditions. The expression of the prognostic markers p53, Ki67, Bcl2 and cyclin D1 was also investigated by immunohistochemistry in endometrial tumours from 11 women with PCO and 16 with normal ovaries.

RESULTS

Overall, PCO were similarly prevalent in women with EC (8.6%) and benign controls (8.4%); however, in women aged <50 years, PCO were more prevalent in women with EC (62.5 versus 27.3%, P = 0.033). Cyclin D1-expressing endometrial tumours tended to be more prevalent in women with PCO compared to normal ovaries (36.4 versus 6.25%, respectively, P = 0.071). Bcl2-, p53- and Ki67-expressing tumours were similarly prevalent.

CONCLUSIONS

The association between PCOS and EC appears confined to premenopausal women. The tendency for cyclin D1-expressing endometrial tumours to be more prevalent in women with PCO challenges the assumption that EC prognosis is improved in women with PCOS.

Maternal hypothyroidism in the rat influences placental and liver glycogen stores: fetal growth retardation near term is unrelated to maternal and placental glucose metabolic compromise

Maternal hypothyroidism impairs fetal growth in the rat, but the mechanisms by which this occurs are unknown. Since the fetus derives its glucose supply from the mother, and maternal thyroidectomy may disturb maternal and placental glucose metabolism, we postulated that maternal and/or placental glucose metabolic compromise may contribute to fetal growth retardation in hypothyroid dams. Feto-placental growth, tissue glycogen stores and glucose levels in sera and amniotic fluid were determined in rat dams partially thyroidectomized (TX) before pregnancy and in euthyroid controls. Fetal body weight at 16, 19 and 21 days gestation (d.g.) was related to pre-mating maternal serum total thyroxine (TT(4)) levels; permanent fetal growth retardation occurred in severely (TX(s); pre-mating maternal serum TT(4)<or=16.19 nM) - but not in moderately (TX(m)) - hypothyroid dams. In TX(s) dams, glycogen concentration was elevated in maternal liver and in the fetal side of the placenta at 16 and 19 d.g., and in the maternal side of the placenta at 19 and 21 d.g., despite maternal euglycemia. In contrast, fetal liver glycogen concentration was deficient in TX(m) dams at 19 d.g. and in TX(s) dams at 19 and 21 d.g., and fetal hypoglycemia occurred in TX(s) dams at 21 d.g. Multiple regression analyses indicate that these fetal deficits are strongly associated with the retardation in fetal growth, while the elevated maternal liver and placental glycogen concentrations have no impact on fetal growth near term. The mechanisms by which severe maternal hypothyroidism permanently retards rat fetal growth remain to be determined.

Influence of maternal hyperthyroidism in the rat on the expression of neuronal and astrocytic cytoskeletal proteins in fetal brain

Maternal hypothyroidism during pregnancy impairs brain function in human and rat offspring, but little is known regarding the influence of maternal hyperthyroidism on neurodevelopment. We have previously shown that the expression of neuronal and glial differentiation markers in fetal brain is compromised in hypothyroid rat dam pregnancies and have now therefore extended this investigation to hyperthyroid rat dams. Study groups comprised partially thyroidectomised dams, implanted with osmotic pumps infusing either vehicle (TX dams) or a supraphysiological dose of thyroxine (T4) (HYPER dams), and euthyroid dams infused with vehicle (N dams). Cytoskeletal protein abundance was determined in fetal brain at 21 days of gestation by immunoblot analysis. Relative to N dams, circulating total T4 levels were reduced to around one-third in TX dams but were doubled in HYPER dams. Fetal brain weight was increased in HYPER dams, whereas litter size and fetal body weight were reduced in TX dams. Glial fibrillary acidic protein expression was similar in HYPER and TX dams, being reduced in both cases relative to N dams. alpha-Internexin (INX) abundance was reduced in HYPER dams and increased in TX dams, whereas neurofilament 68 (NF68) exhibited increased abundance in HYPER dams. Furthermore, INX was inversely related to - and NF68 directly related to - maternal serum total T4 levels, independently of fetal brain weight. In conclusion, maternal hyperthyroidism compromises the expression of neuronal cytoskeletal proteins in late fetal brain, suggestive of a pattern of accelerated neuronal differentiation.

Thyroid hormone receptor expression in rat placenta

The expression of c- erbAalpha and -beta encoded thyroid hormone receptors (TR) was investigated in rat placenta between 16 and 21 days of gestation (dg), and in fetal liver and brain at 16 dg, using semi-quantitative RT-PCR and nuclear 3,5,3'-triiodothyronine (T(3)) binding. TRalpha1, TRbeta1, c- erbAalpha 2 and c- erbAalpha 3 mRNA abundance was unchanged in placenta between 16 and 21 dg, as was the dissociation constant (K(d)) of T(3) binding. The maximal T(3) binding capacity (B(max)) in placenta doubled over this period, suggesting placental TR binding activity is post-transcriptionally regulated. Transcript abundance in tissues at 16 dg can be summarized: TRalpha1, placenta=fetal liver<fetal brain; TRbeta1, placenta=fetal liver>fetal brain; c- erbAalpha 2 and alpha3, placenta=fetal liver<fetal brain; TRbeta2; none detected. T(3)binding in fetal liver and brain exhibited equivalent K(d) and B(max), the K(d) being less than 50 per cent of that in placenta, though B(max) was unchanged. The higher K(d)in placenta may reflect tissue-specific patterns of TR modification. In conclusion, rat placenta expresses significant levels of c- erbAalpha and -beta transcripts and protein, providing a possible mechanism of action for T(3) of maternal and fetal origin in this tissue.

Maternal thyroid status regulates the expression of neuronal and astrocytic cytoskeletal proteins in the fetal brain

Maternal thyroid hormone (TH) crosses the placenta and is postulated to regulate fetal brain development. However, TH-dependent stages of fetal brain development remain to be characterised. We have therefore compared the levels of several neuronal and glial cytoskeletal proteins in fetal brains from normal (N) and partially thyroidectomised (TX) rat dams by immunoblotting. Pregnancies were studied both before and after the onset of fetal TH secretion, which occurs at 17.5 days gestation (dg) in the rat. Maternal hypothyroidism disrupted fetal growth, so that fetal body and brain weights were reduced near term. Vimentin expression was unaffected, however, indicating normal acquisition of neuronal and glial precursor cells. Fetal brain levels of glial fibrillary acidic protein (GFAP) were reduced at 21 dg, suggesting delayed astrocytic differentiation, although regression analysis demonstrated appropriate GFAP levels for brain weight. Levels of alpha-internexin, the earliest neurofilament protein expressed in fetal brain were reduced at 16 dg in TX dams, but increased at 21 dg. The ontogeny of neurofilament-L was also perturbed in these pregnancies, with deficient levels apparent at both 16 and 21 dg. These effects on neuronal cytoskeletal proteins were unrelated to fetal brain growth retardation. These findings confirm that maternal hypothyroidism disrupts early fetal brain development. Early disturbances in neuronal differentiation are not corrected by the onset of fetal TH secretion. Such disturbances may contribute to the neurological damage observed in children born to hypothyroxinaemic mothers.

Maternal hypothyroxinemia influences glucose transporter expression in fetal brain and placenta

The influence of maternal hypothyroxinemia on the expression of the glucose transporters, GLUT1 and GLUT3, in rat fetal brain and placenta was investigated. Fetal growth was retarded in hypothyroxinemic pregnancies, but only before the onset of fetal thyroid hormone synthesis. Placental weights were normal, but placental total protein concentration was reduced at 19 days gestation (dg). Immunoblotting revealed a decreased abundance of GLUT1 in placental microsomes at 16 dg, whereas GLUT3 was increased. Fetal serum glucose levels were reduced at 16 dg. In fetal brain, the concentration of microsomal protein was deficient at 16 dg and the abundance of parenchymal forms of GLUT1 was further depressed, whereas GLUT3 was unaffected. Northern hybridization analysis demonstrated normal GLUT1 mRNA levels in placenta and fetal brain. In conclusion, maternal hypothyroxinemia results in fetal growth retardation and impaired brain development before the onset of fetal thyroid function. Glucose uptake in fetal brain parenchyma may be compromised directly, due to deficient GLUT1 expression in this tissue, and indirectly, as a result of reduced placental GLUT1 expression. Though corrected by the onset of fetal thyroid hormone synthesis, these deficits are present during the critical period of neuroblast proliferation and may contribute to long term changes in brain development and function seen in this model and in the progeny of hypothyroxinemic women.

SHORT COMMUNICATION maternal thyroid dysfunction and c- fos and c- jun expression in rat placenta

Maternal thyroid dysfunction is associated with perturbed fetal brain development and neurological deficits in adulthood in rat and human. To investigate whether these effects occur secondary to placental dysfunction, c- fos and c- jun expression in placenta from normal (euthyroid) and moderately hypothyroid rat dams were investigated by Northern hybridization analysis. In normal placenta, c- fos expression increased by 74 per cent between 16 and 21 days of gestation (dg) whereas c- jun expression declined by 46 per cent. Moderate maternal hypothyroidism depressed placental c- fos expression by 32 per cent at 19 dg, but elevated c- fos and c- jun expression by 139 and 86 per cent, respectively, at 21 dg. Maternal hypothyroidism may therefore induce c- fos/c- jun -related placental dysfunction, but only relatively late in gestation when fetal thyroid function is already established.

Maternal hypothyroxinemia disrupts neurotransmitter metabolic enzymes in developing brain

Maternal thyroid status influences early brain development and, consequently, cognitive and motor function in humans and rats. The biochemical targets of maternal thyroid hormone (TH) action in fetal brain remain poorly defined. A partially thyroidectomized rat dam model was therefore used to investigate the influence of maternal hypothyroxinemia on the specific activities of cholinergic and monoaminergic neurotransmitter metabolic enzymes in the developing brain. Maternal hypothyroxinemia was associated with reduced monoamine oxidase (MAO) activity in fetal whole brain at 16 and 19 days gestation (dg). A similar trend was observed for choline acetyltransferase (ChAT) activity. In contrast, DOPA decarboxylase (DDC) activity was markedly elevated at 21 dg. Further study of these enzymes at 14 dg showed no differences between normal and experimental progeny - suggesting they become TH sensitive after this age. Tyrosine hydroxylase (TyrH) and acetylcholinesterase (AChE) activities were unaffected prenatally. During postnatal development, the activities of TyrH, MAO, DDC and, to a lesser extent, AChE were increased in a brain region- and age-specific manner in experimental progeny. The prenatal disturbances noted in this study may have wide-ranging consequences since they occur when neurotransmitters have putative neurotropic roles in brain development. Furthermore, the chronic disturbances in enzyme activity observed during postnatal life may affect neurotransmission, thereby contributing to the behavioural dysfunction seen in adult progeny of hypothyroxinemic dams.

Exhaled single-breath nitric oxide measurements are reproducible, repeatable and reflect levels of nitric oxide found in the lower airways

Measurement of exhaled nitric oxide (NO) may allow noninvasive assessment of inflammatory disease in the lung. We determined immediate and day-to-day reproducibility of single-breath NO measurements at different points on the exhaled test, and whether levels recorded reflect levels of NO in the lower airways. Using a rapid chemiluminescence analyser, 55 healthy control subjects performed three sequential tests on each of two days. NO levels were compared at the level corresponding with: 1) the time the mouth pressure fell below 4 cmH2O (MP); 2) the plateau of end-exhaled CO2 (CO2); and 3) the NO plateau (NOp). NO levels were measured directly from the lower airways of 15 lung transplant recipients and compared with NO levels from a single-breath test performed in the same cohort. For measurements performed at MP, CO2 and NOp, the mean +/- SD differences between the two closest levels performed on the same day were 0.11+/-0.18, 0.095+/-0.16 and 0.094+/-0.13 parts per billion (ppb), respectively, and between days were 0.18+/-0.76, 0.19+/-0.78 and 0.17+/-0.8 ppb, respectively. End-expiratory levels recorded at the mouth from a single-breath test and in the lower airways were highly correlated (mouth versus trachea r2=0.95, p<0.0001, mouth versus bronchus r2=0.92, p<0.0001). Single-breath exhaled nitric oxide levels are a simple, reproducible and valid measure of nitric oxide production from the lower respiratory tract.

The gastroduodenal mucus barrier and its role in protection against luminal pepsins: the effect of 16,16 dimethyl prostaglandin E2, carbopol-polyacrylate, sucralfate and bismuth subsalicylate

Mucus and bicarbonate secretions have been widely implicated as an important pre-epithelial protective barrier against autodigestion of the gastric mucosa by acid and pepsin. Evidence from several independent studies shows there is a continuous layer of resilient viscoelastic mucus gel adherent to the surface of the gastroduodenal mucosa. The median thickness of the adherent gastric mucus layer in humans is 180 microns, range 50-450 microns. The epithelial bicarbonate secretion permeates the unstirred matrix of mucus gel neutralizing luminal acid and establishing a pH gradient within the gel. In the duodenum, evidence supports the mucus bicarbonate barrier as a major protective mechanism against acid aggression. The adherent mucus gel, by acting as an effective 'permeability' barrier to pepsin, protects the underlying sensitive mucosa from digestion. However, pepsin slowly digests mucus gel at its luminal surface to produce soluble degraded mucin. In a rat gastric damage model in vivo, pepsin in excess digests the gastric mucus barrier sufficiently rapidly to outweigh new mucus secretion and lead to breaching of the mucus barrier with the formation of small punctate ulcers in the epithelium accompanied by mucosal haemorrhage. The mucus secretagogue 16,16 dimethyl prostaglandin E2 and the muco-adhesive carbopol-polyacrylate both fully protected the mucosa against pepsin damage by enhancing the protective properties of the mucus barrier. Sucralfate and bismuth subsalicylate were partially effective in protection against pepsin damage but this protection was mainly mediated at the level of the mucosa. In peptic ulcer disease, there is increased mucolytic (mucus degrading) activity in gastric juice and this is associated with an impaired mucin polymeric structure and a weaker mucus barrier.(ABSTRACT TRUNCATED AT 250 WORDS)

The role of mucus in the protection of the gastroduodenal mucosa

There is good evidence that the adherent mucus plays an important role in the protection of gastroduodenal mucosa from the endogenous aggressors acid and pepsin. Adherent mucus provides a stable unstirred layer which supports surface neutralization of acid by mucosal bicarbonate output and acts as a permeability barrier to luminal pepsin. The adherent mucus layer is continuous. True thickness of the mucus layer and its continuity can only be observed on unfixed sections of mucosa, since histological fixatives and preparation for electron microscopy can cause dehydration and shrinkage of the mucus gel. The structure of adherent gastric mucus is deficient in patients with peptic ulcer disease because of decreased polymerization of the component glycoproteins. This impairment of the mucus barrier is associated with raised amounts of pepsin 1, which digests the mucus layer more aggressively than the major pepsin, pepsin 3, under conditions that pertain both in the stomach (pH 2) and duodenum (pH 4-5). Adherent mucus does not appear to offer much protection against exogenous damaging agents, e.g. alcohol and aspirin. These agents permeate the mucus barrier, damaging the underlying epithelium. The subsequent epithelial repair process is protected by a gelatinous coat over ten times thicker and distinct from the normal adherent mucus layer. Our recent studies show this gelatinous coat to be primarily a fibrin-based gel with mucus and necrotic cells.