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Biomedical subjects

N Qureshi

Publications and source records attributed to N Qureshi.

At least 19 recordsLinked to original sources
PubMed2006

The prevention and management of stroke in sickle cell anaemia.

Perhaps the most important clinical complication of sickle cell anaemia is stroke, an event that occurs in approximately 5-10% of children who inherit this disorder. To prevent recurrent or progressive CNS damage, the institution of regular red blood cell (RBC) transfusions is the standard of care. In addition, children at high risk of developing stroke, as screened by transcranial Doppler, also benefit from regular RBC transfusions for stroke prevention. In this review, standard and novel techniques of RBC transfusion, and also alternative therapies to treat children with or at risk for stroke are considered. In addition, haematopoietic cell transplantation, the only curative option for sickle cell anaemia, is considered, and speculation about its present and future application in this clinical setting is discussed.

Anemia, Sickle Cell↗
PubMed2005

Energy-efficient recovery of butanol from model solutions and fermentation broth by adsorption.

This article discusses the separation of butanol from aqueous solutions and/or fermentation broth by adsorption. Butanol fermentation is also known as acetone butanol ethanol (ABE) or solvent fermentation. Adsorbents such as silicalite, resins (XAD-2, XAD-4, XAD-7, XAD-8, XAD-16), bone charcoal, activated charcoal, bonopore, and polyvinylpyridine have been studied. Use of silicalite appears to be the more attractive as it can be used to concentrate butanol from dilute solutions (5 to 790-810 g L(-1)) and results in complete desorption of butanol (or ABE). In addition, silicalite can be regenerated by heat treatment. The energy requirement for butanol recovery by adsorption-desorption processes has been calculated to be 1,948 kcal kg(-1) butanol as compared to 5,789 kcal kg(-1) butanol by steam stripping distillation. Other techniques such as gas stripping and pervaporation require 5,220 and 3,295 kcal kg(-1) butanol, respectively.

Adsorption↗
PubMed2005

Continuous butanol fermentation and feed starch retrogradation: butanol fermentation sustainability using Clostridium beijerinckii BA101.

Use of starch solution as feed for butanol bioconversion processes employing Clostridium beijerinckii BA101 may have added economic advantage over the use of glucose. Acetone butanol ethanol (ABE) was produced from 30 gL(-1) starch solution using a continuous process. The bioreactor was fed at a dilution rate of 0.02 h(-1) and starch solution/feed volume (3 L) was replaced every 72 h. The continuous reactor fed with cornstarch solution (feed temperature 19 degrees C) produced approximately 6.0 gL(-1) total ABE. Increasing the feed storage temperature to 37 degrees C improved ABE production to 7.2 gL(-1) suggesting that retrogradation was occurring more rapidly at 19 degrees C. In both these cases the fermentation drifted toward acid production after approximately 260 h, consistent with the retrogradation of starch overtime. The use of soluble starch, which is less prone to retrogradation, resulted in the production of 9.9 gL(-1) ABE at 37 degrees C feed storage temperature, as compared to 7.2 gL(-1) ABE when cornstarch was used. It should be noted that gelatinized starch retrogradation takes place after sterilization and prior to use of the feed medium, and does not occur during long-term storage of the raw corn material in the months leading up to processing. The degree of hydrolysis of gelatinized starch decreased from 68.8 to 56.2% in 3 days when stored at 37 degrees C. Soluble starch which does not retrograde demonstrated no change in the degree of hydrolysis.

Acetone↗
PubMed2005

Development of a nosocomial outbreak investigation database.

A pilot web-based database was created to facilitate epidemiological investigation of nosocomial outbreaks. The database provides highly structured abstracts in a case study format to serve as a guide for investigations. Problems encountered in abstracting over 330 published reports included missing information and classification of study methods. The database offers a new way to review outbreaks, for example, in terms of their impact measured by various combinations of database fields, such as the number of cases, attack rate, pathogens, service/ward and mode of transmission. Feedback from users of the database suggests its usefulness. Creation of a large web-based database seems to be both desirable and feasible.

Abstracting and Indexing↗
PubMed2003

Acetone butanol ethanol (ABE) production from concentrated substrate: reduction in substrate inhibition by fed-batch technique and product inhibition by gas stripping.

Acetone butanol ethanol (ABE) was produced in an integrated fed-batch fermentation-gas stripping product-recovery system using Clostridium beijerinckii BA101, with H(2) and CO(2) as the carrier gases. This technique was applied in order to eliminate the substrate and product inhibition that normally restricts ABE production and sugar utilization to less than 20 g l(-1) and 60 g l(-1), respectively. In the integrated fed-batch fermentation and product recovery system, solvent productivities were improved to 400% of the control batch fermentation productivities. In a control batch reactor, the culture used 45.4 g glucose l(-1) and produced 17.6 g total solvents l(-1) (yield 0.39 g g(-1), productivity 0.29 g l(-1) h(-1)). Using the integrated fermentation-gas stripping product-recovery system with CO(2) and H(2) as carrier gases, we carried out fed-batch fermentation experiments and measured various characteristics of the fermentation, including ABE production, selectivity, yield and productivity. The fed-batch reactor was operated for 201 h. At the end of the fermentation, an unusually high concentration of total acids (8.5 g l(-1)) was observed. A total of 500 g glucose was used to produce 232.8 g solvents (77.7 g acetone, 151.7 g butanol, 3.4 g ethanol) in 1 l culture broth. The average solvent yield and productivity were 0.47 g g(-1) and 1.16 g l(-1) h(-1), respectively.

Acetone↗
PubMed2002

Production of butanol from starch-based waste packing peanuts and agricultural waste.

We examined the fermentation of starch-based packing peanuts and agricultural wastes as a source of fermentable carbohydrates using Clostridium beijerinckii BA101. Using semidefined P2 medium containing packing peanuts and agricultural wastes, instead of glucose as a carbohydrate source, we measured characteristics of the fermentation including solvent production, productivity, and yield. With starch as substrate (control), the culture produced 24.7 g l(-1) acetone-butanol-ethanol (ABE), while with packing peanuts it produced 21.7 g l(-1) total ABE with a productivity of 0.20 g l(-1) h(-1) and a solvent (ABE) yield of 0.37. Cell growth in starch, packing peanuts, and agricultural wastes medium was different, possibly due to the different nature of these substrates. Using model agricultural waste, 20.3g l(-1) ABE was produced; when using actual waste, 14.8 g l(-1) ABE was produced. The use of inexpensive substrates will increase the economic viability of the conversion of biomass to butanol, and can provide new markets for these waste streams.

Acetic Acid↗
PubMed2001

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.

Bacterial Proteins↗
PubMed2001

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.

Animals↗
PubMed2001

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.

Brain Diseases↗
PubMed2001

High levels of nitric oxide production decrease early but increase late survival of Brucella abortus in macrophages.

Nitric oxide (NO), produced by the iNOS protein, is known as a defense mechanism against various pathogens and an apoptotic inducer of cells. Apoptosis can also be a host protective mechanism against intracellular bacteria. The intracellular survival of Brucella abortus in RAW264.7 macrophages was examined under conditions of the apoptotic inducer, NO. Since B. abortus does not induce high output of NO, Escherichia coli LPS and IFN-gamma, as potential therapeutic modalities, were added to increase the expression of iNOS, and thus NO. Using 10 ng/ml E. coli LPS and 25 U/ml IFN-gamma, nitrite production was as high as 140 microM by 72 h. However, when macrophages were infected with B. abortus, the nitrite concentration was 60 microM after 72 h post infection, greater than a two-fold decrease. The number of surviving bacteria decreased, from 6 to 24 h, in the presence of nitrite accumulation. In the absence of B. abortus there was an increase in apoptotic cells at 72 h with high nitrite accumulation. In contrast, the number of macrophage apoptotic bodies decreased in the presence of B. abortus. The data suggest that: (i) NO accelerates the killing of intracellular B. abortus, but not to completion during the first 24 h of infection; (ii) B. abortus can prevent apoptosis as an advantage for bacterial survival inside macrophages and (iii) surviving intracellular bacteria then replicate steadily after 24 h. B. abortus probably expresses genes that counteract the effect of a high NO environment or activates genes to utilize NO as a nitrogen source, as the Brucella genome codes for nitric and nitrous oxide reductase genes.

Animals↗
PubMed2001

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.

Aspergillus niger↗
PubMed2001

Recent advances in ABE fermentation: hyper-butanol producing Clostridium beijerinckii BA101.

This is an overview of the mutant strain Clostridium beijerinckii BA101 which produces solvents (acetone-butanol-ethanol, ABE) at elevated levels. This organism expresses high levels of amylases when grown on starch. C. beijerinckii BA101 hydrolyzes starch effectively and produces solvent in the concentration range of 27-29 g x l(-1). C. beijerinckii BA101 has been characterized for both substrate and butanol inhibition. Supplementing the fermentation medium (MP2) with sodium acetate enhances solvent production to 33 g x l(-1). The results of studies utilizing commercial fermentation medium and pilot plant-scale reactors are consistent with the results using small-scale reactors. Pervaporation, a technique to recover solvents, has been applied to fed-batch reactors containing C. beijerinckii BA101, and solvent production as high as 165 g x l(-1) has been achieved. Immobilization of C. beijerinckii BA101 by adsorption and use in a continuous reactor resulted in reactor productivity of 15.8 g x l(-1) x h(-1). Recent economic studies employing C. beijerinckii BA101 suggested that butanol can be produced at US$0.20-0.25 x lb(-1) by employing batch fermentation and distillative recovery. Application of new technologies such as pervaporation, fed-batch culture, and immobilized cell reactors is expected to further reduce these prices.

Acetone↗
PubMed2001

ABE production from corn: a recent economic evaluation.

This article details an economic assessment of butanol production from corn using the newly developed hyper-butanol-producing strain of Clostridium beijerinckii BA101. Butanol is produced in batch reactors and recovered by distillation. For a plant with 153,000 metric tons of acetone, butanol, and ethanol (ABE) production capacity, the production equipment cost and total working capital cost is US$33.47x10(6) and US$110.46x10(6), respectively. Based on a corn price (C(p)) of US$79.23 x ton(-1) (US$2.01 x bushel(-1)), an ABE yield of 0.42 (g ABE/g glucose) butanol price is projected to be US$0.34 x kg(-1). An improved yield of 0.50 will reduce this price to US$0.29 x kg(-1). Assumptions, such as by-product credit for gases and complete conversion of corn steep liquor (CSL) to fermentation by-products, have been taken into consideration. An increased price of corn to US$197.10 x ton(-1) would result in a butanol price of US$0.47 x kg(-1). A grass-rooted plant would result in a butanol price of US$0.73 x kg(-1) (C(p) US$79.23 x ton(-1)). In a worst case scenario, the price of butanol would increase to US$1.07 x kg(-1) (C(p) 197.10 x ton(-1) for a grass-rooted plant and assuming no credit for gases). This is based on the assumption that corn price would not increase to more than US$197.10 x ton(-1).

Acetone↗
PubMed2001

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.

Acetone↗
PubMed2001

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.

Adult↗
PubMed2001

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.

Clinical Competence↗
PubMed2001

Short-chain fatty acids inhibit invasive human colon cancer by modulating uPA, TIMP-1, TIMP-2, mutant p53, Bcl-2, Bax, p21 and PCNA protein expression in an in vitro cell culture model.

High intakes of dietary fiber or resistant starches have been associated with a lower incidence of colon cancers. Because short-chain fatty acids (SCFA) such as butyrate are produced in the colonic lumen by the bacterial fermentation of dietary fibers and resistant starches, we hypothesized that SCFA may inhibit the development of invasive human colon cancers. To test this hypothesis, primary human invasive colonocytes were isolated from fresh surgical specimens and treated with 0.01 mol/L acetate, propionate or butyrate; cell invasion, cell adhesion, F-actin polymerization, urokinase plasminogen activator (uPA), tissue inhibitor matrix metalloproteinase (TIMP)-1, TIMP-2 and mutant p53, Bcl-2, Bax, p21 and proliferating cell nuclear antigen (PCNA) protein expression levels were examined. Although each of the SCFA tested significantly reduced primary cell invasion, butyrate was the most potent, inhibiting primary invasive human colon cancer invasion by 54% (P < 0.0001). The effects of SCFA on primary cell invasion appeared to be independent of cell adhesion and F-actin polymerization but dependent on the inhibition of uPA (P < 0.05) and the stimulation of TIMP-1 and TIMP-2 activities (P < 0.05). Protein expression levels of mutant p53, p21, Bax, Bcl-2 and PCNA were significantly altered by each of the SCFA tested (P < 0.05). These data indicate that SCFA inhibit invasive human colon cancer by modulating proteolytic uPA and antiproteolytic TIMP-1 and TIMP-2 activities, but their mechanisms of action on tumor suppression, apoptosis and growth arrest may differ.

Actins↗