New developments in genetics-knowledge, attitudes and information needs of practice nurses

BACKGROUND

In response to increased referrals to geneticists and the predicted patient demand for genetic counselling, it has been proposed that some genetics services should be provided in primary care. Practice nurses are ideally placed to collect family history information and advise patients accordingly in new patient, family planning, well women/men and chronic disease clinics, but little is known about their knowledge, skills and attitudes towards providing genetic advice.

OBJECTIVES

The survey aimed to measure the current situation with regard to: the prevalence of family history recording by practice nurses; confidence in collecting and acting upon family history; and practice nurses' knowledge about familial disorders and genetics. It also investigated what practice nurses think their role should be in relation to the delivery of genetic services; their educational needs; and the most appropriate ways of delivering training/support.

METHODS

A postal questionnaire survey was carried out of all practices nurses (n = 909) in four Health Authorities in England (Oxfordshire, Northamptonshire, Nottingham and North Nottinghamshire) and one Health Board in Scotland (Lothian). Analyses were primarily descriptive.

RESULTS

A total of 600 nurses (response rate = 66.0%) returned a completed questionnaire. Ninety-six per cent of practice nurses reported that they routinely collect family history information. Over half of the respondents had been consulted in the previous 3 months by patients with a worry about family history of cancer. Approximately 60% of nurses felt confident about collecting the relevant details regarding a family history of breast cancer but felt less confident in collecting the information regarding familial colorectal cancer. Nurses were also unsure how to proceed, with over a third of nurses referring patients to the GP even if they thought the patient was at population risk or, conversely, not referring those that they thought were at considerably higher risk to the GP. There was a reported need for education about familial disease in general and overall agreement that nurses could play a role in genetics in primary care.

CONCLUSION

This study provides evidence of considerable activity from practice nurses regarding routine collection of family history. There is a need for further education for practice nurses regarding family history information and the new genetics so that this information is managed appropriately.

Chlamydia pneumoniae and chlamydial heat shock protein 60 stimulate proliferation of human vascular smooth muscle cells via toll-like receptor 4 and p44/p42 mitogen-activated protein kinase activation

An early component of atherogenesis is abnormal vascular smooth muscle cell (VSMC) proliferation. The presence of Chlamydia pneumoniae in many atherosclerotic lesions raises the possibility that this organism plays a causal role in atherogenesis. In this study, C pneumoniae elementary bodies (EBs) rapidly activated p44/p42 mitogen-activated protein kinases (MAPKs) and stimulated proliferation of VSMCs in vitro. Exposure of VSMCs derived from human saphenous vein to C pneumoniae EBs (3x10(7) inclusion forming units/mL) enhanced bromodeoxyuridine (BrdU) incorporation 12+/-3-fold. UV- and heat-inactivated C pneumoniae EBs also stimulated VSMC proliferation, indicating a role of direct stimulation by chlamydial antigens. However, the mitogenic activity of C pneumoniae was heat-labile, thus excluding a role of lipopolysaccharide. Chlamydial hsp60 (25 microg/mL) replicated the effect of C pneumoniae, stimulating BrdU incorporation 7+/-3-fold. Exposure to C pneumoniae or chlamydial hsp60 rapidly activated p44/p42 MAPK, within 5 to 10 minutes of exposure. In addition, PD98059 and U0126, which are two distinct inhibitors of upstream MAPK kinase 1/2 (MEK1/2), abolished the mitogenic effect of C pneumoniae and chlamydial hsp60. Toll-like receptors (TLRs) act as sensors for microbial antigens and can signal via the p44/p42 MAPK pathway. Human VSMCs were shown to express TLR4 mRNA and protein, and a TLR4 antagonist abolished chlamydial hsp60-induced VSMC proliferation and attenuated C pneumoniae-induced MAPK activation and VSMC proliferation. Together these results indicate that C pneumoniae and chlamydial hsp60 are potent inducers of human VSMC proliferation and that these effects are mediated, at least in part, by rapid TLR4-mediated activation of p44/p42 MAPK.

Diphosphoryl lipid A from Rhodobacter sphaeroides blocks the binding and internalization of lipopolysaccharide in RAW 264.7 cells

Diphosphoryl lipid A derived from the nontoxic LPS of Rhodobacter sphaeroides (RsDPLA) has been shown to be a powerful LPS antagonist in both human and murine cell lines. In addition, RsDPLA also can protect mice against the lethal effects of toxic LPS. In this study, we complexed both the deep rough LPS from Escherichia coli D31 m4 (ReLPS) and RsDPLA with 5- and 30-nm colloidal gold and compared their binding to the RAW 264.7 cell line by electron microscopy. Both ReLPS and RsDPLA bound to the cells with the following observations. First, binding studies revealed that pretreatment with RsDPLA completely blocked the binding and thus internalization of ReLPS-gold conjugates to these cells at both 37 degrees C and 4 degrees C. Second, ReLPS was internalized via micropinocytosis (noncoated plasma membrane invaginations) involving formation of caveolae-like structures and leading to the formation of micropinocytotic vesicles, macropinocytosis (or phagocytosis), formation of clathrin-coated pits (receptor mediated), and penetration through plasma membrane into cytoplasm. Third, in contrast, RsDPLA was internalized predominantly via macropinocytosis. These studies show for the first time that RsDPLA blocks the binding and thus internalization of LPS as observed by scanning and transmission electron microscopy.

Production of glucose oxidase using Aspergillus niger and corn steep liquor

Glucose oxidase production was optimized using an isolated strain of Aspergillus niger and an economical nutrient source, corn steep liquor (CSL). The culture produced 580 +/- 30 units/ml of the enzyme using 70 g/l sucrose as the carbon source. Using CSL as the sole nutrient source enzyme synthesis was increased to 640 +/- 36 units/ml. None of the nitrogen sources (nitrates of calcium, sodium, ammonium, potassium and yeast extract, malt extract, and peptone) was beneficial to the enzyme synthesis. Aeration and agitation enhanced enzyme synthesis to 850 +/- 45 units/ml. Glucose oxidase has numerous applications in food industry and clinical fields.

Soy molasses as fermentation substrate for production of butanol using Clostridium beijerinckii BA101

Spray-dried soy molasses (SDSM) contains the sugars dextrose, sucrose, fructose, pinitol, raffinose, verbascose, melibiose, and stachyose. Of the 746 g kg(-1) total sugars in SDSM, 434 g kg(-1) is fermentable using Clostridium beijerinckii BA101. SDSM was used to produce acetone, butanol, and ethanol (ABE) by C. beijerinckii BA101 in batch cultures. Using 80 g l(-1) SDSM, 10.7 g l(-1) ABE was produced in P2 medium. Higher concentrations of SDSM resulted in poor solvent production due to the presence of excessive salt and inhibitory components. C. beijerinckii BA101 in SDSM at 80 g l(-1) concentration produced 22.8 g l(-1) ABE when supplemented with 25.3 g l(-1) glucose. SDSM contains 57.4 g kg(-1) mineral ash and 2% tri-calcium phosphate. Tri-calcium phosphate up to 43.1 g l(-1) was not inhibitory and at a tri-calcium phosphate concentration of 28.8 g l(-1), the culture produced more solvents (30.1 g l(-1)) than the control experiment (23.8 g l(-1)). In contrast, sodium chloride was a strong inhibitor of C. beijerinckii BA101 cell growth. At a concentration of 10 g l(-1) sodium chloride, a maximum cell concentration of 0.6 g l(-1) was achieved compared to 1.7 g l(-1) in the control experiment. The effects of two salts on specific growth rate constant (mu) and specific rate of ABE production (nu) for C. beijerinckii BA101 were examined.

Signaling by toll-like receptor 2 and 4 agonists results in differential gene expression in murine macrophages

Lipopolysaccharide (LPS) derived from the periodontal pathogen Porphyromonas gingivalis has been reported to differ structurally and functionally from enterobacterial LPS. These studies demonstrate that in contrast to protein-free enterobacterial LPS, a similarly purified preparation of P. gingivalis LPS exhibited potent Toll-like receptor 2 (TLR2), rather than TLR4, agonist activity to elicit gene expression and cytokine secretion in murine macrophages and transfectants. More importantly, TLR2 stimulation by this P. gingivalis LPS preparation resulted in differential expression of a panel of genes that are normally induced in murine macrophages by Escherichia coli LPS. These data suggest that (i) P. gingivalis LPS does not signal through TLR4 and (ii) signaling through TLR2 and through TLR4 differs quantitatively and qualitatively. Our data support the hypothesis that the shared signaling pathways elicited by TLR2 and by TLR4 agonists must diverge in order to account for the distinct patterns of inflammatory gene expression.

A randomized controlled trial to assess the psychological impact of a family history screening questionnaire in general practice

BACKGROUND

It has been postulated that systematic enquiry about patients' family histories of inherited illnesses would lead to a population of 'worried well'.

OBJECTIVE

The purpose of the present study was to evaluate if the use of a family history screening questionnaire (FHSQ) as part of a general practice health check leads to psychological distress.

METHOD

We conducted a randomized controlled trial of a self-administered FHSQ in a single general practice. Individuals who had not had a health check within the previous 2 years were randomized within three age group strata to intervention group (receiving health check and FHSQ) or control group (only receiving health check). A total of 156 patients were offered health checks; 100 accepted and 76 of them were followed through to the 3-month end point. Responses to the six-item Spielberger State-Trait Anxiety Inventory (STAI), Perception of Health questionnaire and Family History Concern questionnaire were compared between intervention and control groups.

RESULTS

A two-way analysis of variance on the STAI scores 1 and 2 weeks after the health check with baseline scores as a covariate showed that at both times anxiety was higher in the intervention group than in the controls (F = 6.4; d.f. = 1,73; P = 0.014). Three months later, there was no significant difference between the two groups. The Perception of Health questionnaire only showed a significant result at 1 week, the intervention group having a more pessimistic response to the question eliciting patient's concerns about future health (P = 0.025).

CONCLUSION

Short-term psychological distress due to the family history screening questionnaire was identified but did not persist.

Prenatal cocaine exposure and cranial sonographic findings in preterm infants

PURPOSE

Prenatal cocaine exposure has been linked with subependymal hemorrhage and the formation of cysts that are detectable on cranial sonography in neonates born at term. We sought to determine if prenatal cocaine exposure increases the incidence of subependymal cysts in preterm infants.

METHODS

We retrospectively reviewed the medical records and cranial sonograms obtained during a 1-year period on 122 premature (< 36 weeks of gestation) infants. Infants were categorized into 1 of 2 groups: those exposed to cocaine and those not exposed to cocaine. Infants were assigned to the cocaine-exposed group if there was a maternal history of cocaine abuse during pregnancy or if maternal or neonatal urine toxicology results were positive at the time of delivery.

RESULTS

Five of the 122 infants were excluded from the study because of insufficient medical and drug histories. The incidence of subependymal cysts in the 117 remaining infants was 14% (16 of 117). The incidence of subependymal cysts in infants exposed to cocaine prenatally was 44% (8 of 18) compared with 8% (8 of 99) in the unexposed group (p < 0.01).

CONCLUSIONS

We found an increased incidence of subependymal cyst formation in preterm infants who were exposed to cocaine prenatally. This result is consistent with results of similar studies in term infants.

Butanol production using Clostridium beijerinckii BA101 hyper-butanol producing mutant strain and recovery by pervaporation

Clostridium beijerinckii BA101 (mutant strain) and C. beijerinckii 8052 (wild type) were compared for substrate and butanol inhibition. The wild-type strain is more strongly inhibited by added butanol than is the mutant strain. Acetone and butanol were removed from a fed-batch reactor inoculated with C. beijerinckii BA101 by pervaporation using a silicone membrane. In the batch reactor, C. beijerinckii BA101 produced 25.3 g/L of total solvents, whereas in the fermentation-recovery experiment it produced 165.1 g/L of total solvents. Solvent productivity increased from 0.35 (batch reactor) to 0.98 g/L.h (fed-batch reactor). The fed-batch reactor was fed with 500 g/L of glucose-based P2 medium. Acetone selectivities ranged from 2 to 10 whereas butanol selectivities ranged from 7 to 19. Total flux varied from 26 to 31 g/m2.h.

Nitric oxide synthesis and TNF-alpha secretion in RAW 264.7 macrophages: mode of action of a fermented papaya preparation

Macrophage inducible nitric oxide synthase is able to generate massive amounts of nitric oxide (NO) which contributes to the host immune defense against viruses and bacteria. Monocyte-macrophages stimulated with the bacterial wall component lipopolysaccharide (LPS) and cytokines such as interferon-gamma (IFN-gamma) express the inducible form of nitric oxide synthase (iNOS). Furthermore, tumor necrosis factor-alpha (TNF-alpha) is one of the central regulatory cytokines in macrophage antimicrobial activity and synergizes with IFN-gamma in the induction of NO synthesis. Because of its pivotal role in both antimicrobial and tumoricidal activities of macrophages, a significant effort has focused on developing therapeutic agents that regulate NO production. In the present study fermented papaya preparation (FPP) is shown to exert both immunomodulatory and antioxidant activity in the macrophage cell line RAW 264.7. Interestingly, a low and a high molecular weight fraction (LMF and HMF, respectively) of FPP exhibited different activity patterns. FPP fractions alone did not affect NO production. However in the presence of IFN-gamma, both LMF and HMF significantly increased iNOS activity and nitrite as well as nitrate accumulation. NO radical formation measured in real-time by electron paramagnetic resonance spectroscopy was higher in the presence of LMF and IFN-gamma. On the contrary, iNOS mRNA levels were enhanced further with HMF than with LMF. Moreover, LMF displayed a stronger superoxide anion scavenging activity than HMF. In the presence of IFN-gamma, both FPP fractions stimulated TNF-alpha secretion. However in non-stimulated macrophages, TNF-alpha secretion was enhanced by HMF only. Since water-soluble FPP fractions contained no lipid A, present data indicate that FPP is a macrophage activator which augments nitric oxide synthesis and TNF-alpha secretion independently of lipopolysaccharides.

Effects of single and multiple courses of antenatal glucocorticoids in preterm newborns less than 30 weeks' gestation

BACKGROUND

We compared outcomes between neonates receiving either single course, multiple courses, or no antenatal glucocorticoid exposure.

METHODS

We retrospectively identified neonates whose mothers received a single course (SIN) of dexamethasone, multiple (2-3) weekly courses (MULT), or no (NO) glucocorticoids. Multiple gestations and infants with chromosomal abnormalities or not receiving a full course of antenatal dexamethasone were excluded from the study. The incidences of the following outcomes were examined: respiratory distress syndrome (RDS), Grades III or IV intraventricular hemorrhage (IVH), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), sepsis, and in-hospital death. Means were compared with analysis of variance and outcome variable frequencies with chi-square test.

RESULTS

A total of 147 infants were included in the analysis. There were no differences in the gestational age or growth parameters among the groups. As anticipated, infants exposed to antenatal glucocorticoids had a significantly lower incidence of morbidities (BPD, NEC, and IVH) than the unexposed infants. There were no differences in the incidence of RDS, IVH, BPD, NEC, ROP, PDA, sepsis, or death between the SIN and MULT groups.

CONCLUSION

A single course of antenatal glucocorticoid therapy is associated with improved neonatal outcomes in infants less than 30 weeks' gestation. Multiple courses were not shown to confer additional benefits, but further investigation is required to definitively address the need for weekly treatment.

Neutrophil activation by bacterial lipoprotein versus lipopolysaccharide: differential requirements for serum and CD14

Neutrophil activation plays an important role in the inflammatory response to Gram-negative bacterial infections. LPS has been shown to be a major mediator of neutrophil activation which is accompanied by an early down-regulation of L-selectin and up-regulation of CD1lb/CD18. In this study, we investigated whether lipoprotein (LP), the most abundant protein in the outer membrane of bacteria from the family Enterobacteriaceae, can activate neutrophils and whether this activation is mediated by mechanisms that differ from those used by LPS or Escherichia coli diphosphoryl lipid A (EcDPLA). Neutrophil activation was assessed by measuring down-regulation of L-selectin and up-regulation of CD11b/CD18. When comparing molar concentrations of LP vs EcDPLA, LP was more potent (four times) at activating neutrophils. In contrast to LPS/EcDPLA, LP activation of neutrophils was serum independent. However, LP activation of neutrophils was enhanced by the addition of soluble CD14 and/or LPS-binding protein. In the presence of serum, LP activation of neutrophils was inhibited by different mAbs to CD14. This inhibition was significantly reduced or absent when performed in the absence of serum. Diphosphoryl lipid A from Rhodobacter spheroides (RaDPLA) completely inhibited LPS/EcDPLA activation of neutrophils but only slightly inhibited LP activation of neutrophils. These results suggest that LP activation of human neutrophils can be mediated by a mechanism that is different from LPS activation and that LP is a potentially important component in the development of diseases caused by Gram-negative bacteria of the family Enterobacteriaceae.

Toll-like receptor 4 imparts ligand-specific recognition of bacterial lipopolysaccharide

Lipopolysaccharide (LPS) is the main inducer of shock and death in Gram-negative sepsis. Recent evidence suggests that LPS-induced signal transduction begins with CD14-mediated activation of 1 or more Toll-like receptors (TLRs). The lipid A analogues lipid IVa and Rhodobacter sphaeroides lipid A (RSLA) exhibit an uncommon species-specific pharmacology. Both compounds inhibit the effects of LPS in human cells but display LPS-mimetic activity in hamster cells. We transfected human TLR4 or human TLR2 into hamster fibroblasts to determine if either of these LPS signal transducers is responsible for the species-specific pharmacology. RSLA and lipid IVa strongly induced NF-kappaB activity and IL-6 release in Chinese hamster ovary fibroblasts expressing CD14 (CHO/CD14), but these compounds antagonized LPS antagonists in CHO/CD14 fibroblasts that overexpressed human TLR4. No such antagonism occurred in cells overexpressing human TLR2. We cloned TLR4 from hamster macrophages and found that human THP-1 cells expressing the hamster TLR4 responded to lipid IVa as an LPS mimetic, as if they were hamster in origin. Hence, cells heterologously overexpressing TLR4 from different species acquired a pharmacological phenotype with respect to recognition of lipid A substructures that corresponded to the species from which the TLR4 transgene originated. These data suggest that TLR4 is the central lipid A-recognition protein in the LPS receptor complex.

The 'new genetics' and primary care: GPs' views on their role and their educational needs

BACKGROUND

Given the limited specialist resources available to cope with the rising demand for genetic services, it has been proposed that at least some of these services are provided by primary care in the future.

OBJECTIVE

We aimed to explore GPs' attitudes towards new developments in genetics, to establish the role they envisage for primary care and to clearly define the education, information and training needed to support them in this role.

METHODS

We carried out a qualitative study with GPs using four focus groups (26 GPs) and 15 individual semi-structured interviews.

RESULTS

GPs perceive genetics as an important and increasingly relevant topic for primary care. Views on the appropriate level of involvement for primary care are mixed. GPs currently lack the relevant knowledge and skills to manage patients concerned about their family history. Other potential barriers to increasing primary care involvement included the time and costs involved, and ethical and legal concerns.

CONCLUSION

If primary care is to become more involved in the delivery of genetic services in the future, then a major educational effort is required to raise awareness of the potential scope and limitations of new developments.

Production of acetone butanol ethanol (ABE) by a hyper-producing mutant strain of Clostridium beijerinckii BA101 and recovery by pervaporation

A silicone membrane was used to study butanol separation from model butanol solutions and fermentation broth. Depending upon the butanol feed concentration in the model solution and pervaporation conditions, butanol selectivities of 20.88-68.32 and flux values of 158.7-215.4 g m(-)(2) h(-)(1) were achieved. Higher flux values (400 g m(-)(2) h(-)(1)) were obtained at higher butanol concentrations using air as sweep gas. In an integrated process of butanol fermentation-recovery, solvent productivities were improved to 200% of the control batch fermentation productivities. In a batch reactor the hyper-butanol-producing mutant strain C. beijerinckii BA101 utilized 57.3 g/L glucose and produced 24.2 g/L total solvents, while in the integrated process it produced 51.5 g/L (culture volume) total solvents. Concentrated glucose medium was also fermented. The C. beijerinckii BA101 mutant strain was not negatively affected by the pervaporative conditions. In the integrated experiment, acids were not produced. With the active fermentation broth, butanol selectivity was reduced by a factor of 2-3. However, the membrane flux was not affected by the active fermentation broth. The butanol permeate concentration ranged from 26.4 to 95.4 g/L, depending upon butanol concentration in the fermentation broth. Since the permeate of most membranes contains acetone, butanol, and ethanol (and small concentrations of acids), it is suggested that distillation be used for further purification.

Limited role of ceramide in lipopolysaccharide-mediated mitogen-activated protein kinase activation, transcription factor induction, and cytokine release

The involvement of ceramide in lipopolysaccharide-mediated activation of mouse macrophages was studied. Lipopolysaccharide, cell-permeable ceramide analogs, and bacterial sphingomyelinase led to phosphorylation of the extracellular signal-regulated kinases, c-Jun NH2-terminal kinases, and p38 kinase and induced AP-1 DNA binding in C3H/OuJ (Lpsn) but not in C3H/HeJ (Lpsd) macrophages. Lipopolysaccharide and ceramide mimetics showed distinct kinetics of mitogen-activated protein kinase phosphorylation and AP-1 induction and activated AP-1 complexes with different subunit compositions. Lipopolysaccharide-activated AP-1 consisted of c-Fos, Jun-B, Jun-D, and c-Jun, while C2-ceramide induced Jun-D and c-Jun only. Lipopolysaccharide and, less potently, C2-ceramide or sphingomyelinase, stimulated AP-1-dependent reporter gene transcription in RAW 264.7 cells. Unlike lipopolysaccharide, C2-ceramide failed to activate NF-kappaB and did not induce production of tumor necrosis factor or interleukin-6. The lipopolysaccharide antagonist, Rhodobacter sphae-roides diphosphoryl lipid A, inhibited lipopolysaccharide activation of NF-kappaB and AP-1 but did not block C2-ceramide-induced AP-1. Pretreatment of C3H/OuJ macrophages with C2-ceramide greatly diminished AP-1 induction following subsequent C2-ceramide stimulation. However, lipopolysaccharide-induced transcription factor activation and cytokine release were not influenced. In contrast, lipopolysaccharide pretreatment inhibited both lipopolysaccharide- and C2-ceramide-mediated responses. Thus, ceramide partially mimics lipopolysaccharide in activating the mitogen-activated protein kinases and AP-1 but not in mediating NF-kappaB induction or cytokine production, suggesting a limited role in lipopolysaccharide signaling.

Lipopolysaccharides (LPS) of oral black-pigmented bacteria induce tumor necrosis factor production by LPS-refractory C3H/HeJ macrophages in a way different from that of Salmonella LPS

Some lipopolysaccharide (LPS) preparations from S- or R-form members of the family Enterobacteriaceae and oral black-pigmented bacteria (Porphyromonas gingivalis and Prevotella intermedia) are known to activate LPS-refractory C3H/HeJ macrophages. When contaminating proteins are removed from R-form LPS of Enterobacteriaceae by repurification, however, this ability is lost. In the present study, we investigated the capacity of LPS from P. gingivalis, P. intermedia, Salmonella minnesota, and Salmonella abortusequi to induce production of tumor necrosis factor (TNF) in gamma interferon-primed C3H/HeJ macrophages before and after repurification. P. abortusequi S-LPS was fractionated by centrifugal partition chromatography into two LPS forms: SL-LPS, having homologous long O-polysaccharide chains, and SS-LPS having short oligosaccharide chains. Prior to repurification, all LPS forms except SL-LPS induced TNF production in both C3H/HeJ and C3H/HeN macrophages. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that repurification removed contaminating protein from the preparations, and repurified SS-LPS and S. minnesota Ra-LPS no longer stimulated TNF production in C3H/HeJ macrophages, although C3H/HeN macrophages remained responsive. In contrast, repurified oral bacterial LPS retained the capacity to induce TNF production in C3H/HeJ macrophages. Oral bacterial LPS preparations also were not antagonized by excess inactive, repurified SL-LPS; Ra-LPS; Rhodobacter sphaeroides lipid A, a competitive LPS antagonist, or paclitaxel, an LPS agonist, and they were comparatively resistant to polymyxin B treatment. Nevertheless, oral bacterial LPS was less toxic to D-galactosamine-treated C3H/HeN mice than was LPS from Salmonella. These findings indicate that the active molecule(s) and mode of action of LPS from P. gingivalis and P. intermedia are quite different from those of LPS from Salmonella.

Fluctuating silicate:nitrate ratios and coastal plankton food webs

Marine diatoms require dissolved silicate to form an external shell, and their growth becomes Si-limited when the atomic ratio of silicate to dissolved inorganic nitrogen (Si:DIN) approaches 1:1, also known as the "Redfield ratio." Fundamental changes in the diatom-to-zooplankton-to-higher trophic level food web should occur when this ratio falls below 1:1 and the proportion of diatoms in the phytoplankton community is reduced. We quantitatively substantiate these predictions by using a variety of data from the Mississippi River continental shelf, a system in which the Si:DIN loading ratio has declined from around 3:1 to 1:1 during this century because of land-use practices in the watershed. We suggest that, on this shelf, when the Si:DIN ratio in the river decreases to less than 1:1, then (i) copepod abundance changes from >75% to <30% of the total mesozooplankton, (ii) zooplankton fecal pellets become a minor component of the in situ primary production consumed, and (iii) bottom-water oxygen consumption rates become less dependent on relatively fast-sinking (diatom-rich) organic matter packaged mostly as zooplankton fecal pellets. This coastal ecosystem appears to be a pelagic food web dynamically poised to be either a food web composed of diatoms and copepods or one with potentially disruptive harmful algal blooms. The system is directed between these two ecosystem states by Mississippi River water quality, which is determined by land-use practices far inland.

Lipopolysaccharide and its analog antagonists display differential serum factor dependencies for induction of cytokine genes in murine macrophages

Monocytes/macrophages play a central role in mediating the effects of lipopolysaccharide (LPS) derived from gram-negative bacteria by the production of proinflammatory mediators. Recently, it was shown that the expression of cytokine genes for tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and interferon-inducible protein-10 (IP-10) by murine macrophages in response to low concentrations of LPS is entirely CD14 dependent. In this report, we show that murine macrophages respond to low concentrations of LPS ( Collapse

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MESH Headings

• Acute-Phase Proteins
• Animals
• Carrier Proteins/pharmacology
• Chemokine CXCL10
• Chemokines, CXC/biosynthesis
• Culture Media, Serum-Free
• Cytokines/biosynthesis
• Disaccharides/pharmacology
• Dose-Response Relationship, Drug
• Escherichia coli
• Female
• Gene Expression Regulation
• Interleukin-1/biosynthesis
• Lipid A/analogs & derivatives
• Lipid A/pharmacology
• Lipopolysaccharide Receptors/genetics
• Lipopolysaccharide Receptors/pharmacology
• Lipopolysaccharides/antagonists & inhibitors
• Lipopolysaccharides/immunology
• Macrophages/immunology
• Male
• Membrane Glycoproteins
• Mice
• Mice, Inbred C3H
• Mice, Knockout
• Monosaccharides/pharmacology
• Tumor Necrosis Factor-alpha/biosynthesis

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Grants

• R37 AI018797 NIAID NIH HHS
• AI 18797 NIAID NIH HHS
• GM 50870 NIGMS NIH HHS
• R01 GM050870 NIGMS NIH HHS
• R01 AI018797 NIAID NIH HHS
• R56 AI018797 NIAID NIH HHS

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