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Biomedical subjects

K Patel

Publications and source records attributed to K Patel.

At least 37 records · Page 2Linked to original sources
PubMed2003

A randomised clinical trial to assess the effect of total enteral and total parenteral nutritional support on metabolic, inflammatory and oxidative markers in patients with predicted severe acute pancreatitis (APACHE II > or =6).

BACKGROUND: Total enteral nutrition (TEN) within 48 h of admission has recently been shown to be safe and efficacious as part of the management of severe acute pancreatitis. Our aim was to ascertain the safety of immediate TEN in these patients and the effect of TEN on systemic inflammation, psychological state, oxidative stress, plasma glutamine levels and endotoxaemia. METHODS: Patients admitted with predicted severe acute pancreatitis(APACHE II score >5) were randomised to total enteral (TEN; n = 8) or total parenteral nutrition (TPN; n = 9). Measurements of systemic inflammation (C-reactive protein), fatigue (visual analogue scale), oxidative stress (plasma thiobarbituric acid-reactive substances), plasma glutamine and anti-endotoxin IgG and IgM antibody concentrations were made on admission and repeated on days 3 and 7 thereafter. Clinical progress was monitored using APACHE II score. Organ failure and complications were recorded. RESULTS: All patients tolerated the feeding regime well with few nutrition-related complications. Fatigue improved in both groups but more rapidly in the TEN group. Oxidative stress was high on admission and rose by similar amounts in both groups. Plasma glutamine concentrations did not change significantly in either group. In the TPN group, 3 patients developed respiratory failure and 3 developed non-respiratory single organ failure. There were no such complications in the TEN group. Hospital stay was shorter in the TEN group [7(4-14) vs. 10 (7-26) days; p = 0.05] as was time to passing flatus and time to opening bowels [1 (0-2) vs. 2 (1-5)days; p = 0.01]. The cost of TEN was considerably less than of TPN. CONCLUSION: Immediate institution of nutritional support in the form of TEN is safe in predicted severe acute pancreatitis. It is as safe and as efficacious as TPN and may be beneficial in the clinical course of this disease.

APACHE↗
PubMed2003

Evaluation of spinal ultrasound in spinal dysraphism.

AIMS: The aims of this study were to evaluate the role of spinal ultrasound in detecting occult spinal dysraphism (OSD) in neonates and infants, and to determine the degree of agreement between ultrasound and magnetic resonance imaging (MRI) findings. MATERIALS AND METHODS: Eighty-five consecutive infants had spinal ultrasound over 31 months. Of these, 15 patients (age 1 day-7 months, mean 40 days; nine male) had follow-up MRI. Ultrasound and MRI findings were correlated retrospectively. RESULTS: Six out of 15 (40%) ultrasound examinations showed full agreement with MRI, seven of 15 (47%) had partial agreement, and two of 15 (13%) had no agreement. In the present series ultrasound failed to visualize: four of four dorsal dermal sinuses, three of four fatty filum terminales, one of one terminal lipoma, two of four partial sacral agenesis, three of four hydromyelia and one of 10 low-lying cords. CONCLUSION: Agreement between ultrasound and MRI was good, particularly for the detection of low-lying cord (90%). Therefore we recommend ultrasound as a first-line screening test for OSD. If ultrasound is abnormal, equivocal or technically limited, MRI is advised for full assessment.

Female↗
PubMed2003

The rate of fibrosis progression is an independent predictor of the response to antiviral therapy in chronic hepatitis C.

The response to antiviral therapy and the rate of fibrosis progression in chronic hepatitis C virus (HCV) infection are related to common factors, including age and gender. The aim of this study was to evaluate the relationship between the rate of fibrosis progression and the sustained virologic response (SVR) to interferon (IFN)-based treatment. A total of 332 patients treated for chronic HCV infection were evaluated. Using multivariate logistic regression analysis, the impact of the rate of fibrosis progression (defined as the stage of liver fibrosis according to the Metavir system/duration of infection) on the rate of SVR (negative HCV RNA at least 6 months following the end of treatment), was determined. The median age of the patients was 44 (range 25-77) years, 64% were male, and 66% were infected with genotypes 1, 4, 5 or 6. The median rate of fibrosis progression was 0.083 (range 0-2) Metavir units/year; 158 patients (48%) had F2-F4 fibrosis. After a median of 48 (range 2-126) weeks of therapy (IFN, n=190; IFN and ribavirin, n=96; pegylated IFN, n=20; pegylated IFN and ribavirin, n=26), 93 patients (28%) achieved an SVR. In univariate analysis, the rate of SVR was higher in slow [< 0.083 Metavir units/year (n=162)] than rapid progressors [> or = 0.083 Metavir units/year (n=170)] (35%vs 22%, P=0.01). After controlling for age, gender, genotype, viral load, and treatment regimen and duration, the rate of fibrosis progression remained an independent predictor of SVR (slow vs rapid progressors, OR 2.74; 95% CI 1.27-5.92; P=0.01). Hence the rate of fibrosis progression is an independent predictor of SVR to IFN-based therapy in patients with chronic hepatitis C. This additional factor should be considered in economic models evaluating this condition.

Adult↗
PubMed2003

Complex chimeras to map ligand binding sites of GPCRs.

Family 1a GPCRs are thought to bind small molecule ligands in a pocket comprising sequences from non-contiguous transmembrane helices. In this study, receptor-ligand binding determinants were defined by building a series of complex chimeras where multiple sequences were exchanged between related G-protein coupled receptors. Regions of P2Y(1), P2Y(2) and BLT(1) predicted to interact with nucleotide and leukotriene ligands were identified and receptors were engineered within their transmembrane helices to transpose the ligand binding site of one receptor on to another receptor. Ligand-induced activation of chimeras was compared with wild-type receptor activation in a yeast reporter gene assay. Binding of ligand to a P2Y(2)/BLT(1) chimera confirmed that the ligand binding determinants of BLT(1) are located in the upper regions of the helices and extracellular loops of this receptor and that they had been successfully transferred to a receptor that normally binds unrelated ligands.

Amino Acid Sequence↗
PubMed2003

Detection and consequences of recombinant protein isoforms: implications for biological potency.

Various types of structural variants have been observed in recombinant DNA - derived products. These isoforms include variations in post translational carbohydrate modifications where variations in site occupancy or unoccupied sites may occur. In addition, varying degrees of C-terminal processing and N-terminal substitutions have been observed. Isoforms may also be generated during processing and can include aggregated and/or chemically modified forms of the protein. Sophisticated analytical techniques exist for the identification and characterization of these structural variants. Several strategies have been used to isolate or enrich the isoform before molecular characterization. However, the effect these structural variations have on the biological activity of the product is less well understood. This may, in part, be due to the specificity and variability of the bioassay employed. This presentation describes the isolation and characterization of specific molecular isoforms for a monoclonal antibody product as well as an assessment of effects on biological activity.

Animals↗
PubMed2002

A genotypic association implicates myeloperoxidase in the progression of hepatic fibrosis in chronic hepatitis C virus infection.

The hepatitis C virus (HCV) is a major cause of liver disease and the complications of cirrhosis. Liver biopsies, performed prior to the development of liver cirrhosis, characteristically show an inflammatory cell infiltrate with varying degrees of fibrosis. Precisely how HCV infection induces hepatic fibrogenesis is unknown. Recent studies suggest the release of oxidants, cytokines and proteases from the host immune system are key to the development of fibrosis. Macrophages and neutrophils, cells heavily represented in the inflammatory cell response, contain the oxidant generating enzyme myeloperoxidase (MPO). Cellular levels of MPO can be influenced by a functional promotor polymorphism, -463G/A, which precedes the MPO gene. We examined the relationship between this MPO promotor genotype and the degree of fibrosis in 166 patients with chronic HCV infection. All patients had previously participated in clinical drug trials for the treatment of chronic HCV infection. The MPO genotype was determined from cryo-preserved lymphocytes obtained from patients prior to treatment. The degree of fibrosis was estimated from liver biopsy specimens obtained prior to treatment. We found that patients with the MPO GA/AA genotype were more likely to have advanced fibrosis scores compared with those with the GG genotype: Of the patients with GG genotype, 78% (79 of 102 cases) had lower Knodell Fibrosis scores of 0 or 1, compared to 56% (37 of 64 cases) of patients with GA/AA genotype (P < 0.05). The mechanism(s) by which MPO contributes to fibrosis progression remains to be determined.

Female↗
PubMed2002

External cervical resorption associated with localized gingival overgrowth.

AIM: To describe the presentation and management of an unusual lesion of external cervical resorption. SUMMARY: The salient features of this unusual presentation of the external cervical resorption with localized gingival overgrowth, and the resorption located almost wholly on the labial aspect of a maxillary incisor crown are described. Extensive loss of enamel had occurred. The management and possible aetiology of the resorptive lesion are discussed. KEY LEARNING POINTS: Localized gingival overgrowth can be associated with external cervical resorption.The cervical resorption does not necessarily indicate pulp canal infection and the need for root-canal treatment.

Adult↗
PubMed2002

Spinal ultrasound in infants.

This paper discusses the indications for spinal ultrasound, including its advantages and disadvantages compared with spinal MRI. The features and ultrasound findings both in normal infants and in those with spinal dysraphism are reviewed.

Humans↗
PubMed2002

Detection and consequences of recombinant protein isoforms: implications for biological potency.

Protein isoforms commonly occur in nature and in products produced by recombinant DNA technologies. Some isoforms may be generated as a consequence of the manufacturing process. Bioassay methods may not be sufficiently sensitive enough or specific enough to determine the biological effect of having a new or increased level of a particular isoform. Sophisticated analytical techniques exist for the structural characterization of protein isoforms. The biological implications of these isoforms are not easy to determine. Additional "Biological Characterization" work may need to be done to evaluate the biological consequences of isoforms. An understanding of the product's mechanism of action and the disease mechanism of action is essential for a thorough evaluation.

Electrophoresis, Polyacrylamide Gel↗
PubMed2001

Dominant paternal transmission of Cornelia de Lange syndrome: a new case and review of 25 previously reported familial recurrences.

The Cornelia de Lange syndrome (CdLS) is an autosomal dominant multisystem disorder characterized by somatic and cognitive retardation, characteristic facial features, limb abnormalities, hearing loss, and other organ system involvement. The vast majority of cases (99%) are sporadic, with rare familial occurrences having been reported. Most individuals with CdLS do not reproduce as a result of the severity of the disorder. Maternal transmission has been well documented, as have several cases of multiple-affected children being born to apparently unaffected parents. Paternal transmission has rarely been reported. A case is reported here of a father with classic features of CdLS with a similarly affected daughter. A review of the reported familial cases of CdLS is summarized.

Adult↗
PubMed2001

Advances in the stable isotope-mass spectrometric measurement of DNA synthesis and cell proliferation.

Methods for measuring rates of DNA synthesis, and thus cell proliferation, in humans had not been available until recently. We (D. C. Macallan, C. A. Fullerton, R. A. Neese, K. Haddock, S. S. Park, and M. K. Hellerstein, 1998, Proc. Natl. Acad. Sci. USA 95, 708-713) recently developed a stable isotope-mass spectrometric technique for measuring DNA synthesis by labeling the deoxyribose (dR) moiety of purine deoxyribonucleotides through the de novo nucleotide synthesis pathway. The original analytic approach had limitations, however. Here, we describe technical improvements that increase yield, stability, sensitivity, and reproducibility of the method. The purine deoxyribonucleoside, deoxyadenosine (dA), is directly isolated from hydrolysates of DNA by using an LC18 SPE column. Two derivatives were developed for analyzing the dR moiety of dA alone (without the base), an aldonitrile-triacetate derivative, and a reduced pentose-tetraacetate (PTA) derivative. The PTA derivative in particular exhibited greater stability (no degradation after several weeks), greater GC/MS signal, and much less abundance sensitivity of isotope ratios (i.e., less dependence of mass isotopomer abundances on the amount of material injected into the mass spectrometer source), compared to previous derivatives of dA. The need for complex, multidimensional abundance corrected standard curves was thereby avoided. Using the PTA derivative, dR enrichments from DNA of fully turned over cells of rodents with 2H2O enrichments in body water of 2.2-2.8% were 9.0-9.5%, and less than 1.0 microg DNA (ca. 2 x 10(5) cells) was required for reproducible analyses. In summary, these methodologic advances allow measurement of stable isotope incorporation into DNA and calculation of cell proliferation and death rates in vivo in humans and experimental animals, with fewer cells, greater reproducibility, and less labor. Many applications of this approach can be envisioned.

Animals↗
PubMed2001

Activity of diadenosine polyphosphates at P2Y receptors stably expressed in 1321N1 cells.

The selectivities of the diadenosine polyphosphates (Ap(n)As, n=2-6) at the human P2Y(1), P2Y(2), P2Y(4), P2Y(6) and P2Y(11) receptors stably expressed in 1321N1 human astrocytoma cells was determined using a Fluorescence Imaging Plate Reader (FLIPR) to measure intracellular Ca(2+) mobilisation. The rank order of agonist potencies at P2Y(1) were: ADP>P(1),P(3)-diadenosine triphosphate (Ap(3)A)>P(1),P(3)-diadenosine hexaphosphate (Ap(6)A)=P(1),P(3)-diadenosine diphosphate (Ap(2)A)>>P(1),P(3)-diadenosine pentaphosphate (Ap(5)A). P(1),P(3)-diadenosine tetraphosphate (Ap(4)A) was inactive up to 1 mM. The rank order of agonist potencies at P2Y(2) were: UTP>Ap(4)A>>Ap(6)A>Ap(5)A>Ap(3)A>>Ap(2)A. The Ap(4)A concentration response curve appeared to be bi-phasic. At P2Y(4) all the Ap(n)As tested were inactive as agonists. At P2Y(6), only Ap(3)A and Ap(5)A showed significant agonist activity. At P2Y(11), only Ap(4)A showed significant agonist activity. Ap(n)As were inactive as antagonists of the P2Y(1), P2Y(2), P2Y(4), P2Y(6) and P2Y(11) receptors. At P2Y(4), however, the Ap(n)As potentiated the UTP response.

Adenosine Diphosphate↗
PubMed2001

Arterial identity of endothelial cells is controlled by local cues.

The ephrins and their Eph receptors comprise the largest family of receptor tyrosine kinases. Studies on mice have revealed an important function of ephrin-B2 and Eph-B4 for the development of the arterial and venous vasculature, respectively, but the mechanisms regulating their expression have not been studied yet. We have cloned a chick ephrin-B2 cDNA probe. Expression was observed in endothelial cells of extra- and intraembryonic arteries and arterioles in all embryos studied from day 2 (stage 10 HH, before perfusion of the vessels) to day 16. Additionally, expression was found in the somites and neural tube in early stages, and later also in the smooth muscle cells of the aorta, parts of the Müllerian duct, dosal neural tube, and joints of the limbs. We isolated endothelial cells from the internal carotid artery and the vena cava of 14-day-old quail embryos and grafted them separately into day-3 chick embryos. Reincubation was performed until day 6 and the quail endothelial cells were identified with the QH1 antibody. The grafted arterial and venous endothelial cells expressed ephrin-B2 when they integrated into the lining of arteries. Cells that were not integrated into vessels, or into vessels other than arteries, were ephrin-B2-negative. The studies show that the expression of the arterial marker ephrin-B2 is controlled by local cues in arterial vessels of older embryos. Physical forces or the media smooth muscle cells may be involved in this process.

Animals↗
PubMed2001

Simple bedside additive tool for prediction of in-hospital mortality after percutaneous coronary interventions.

BACKGROUND: Risk-adjustment models for percutaneous coronary intervention (PCI) mortality have been recently reported, but application in bedside prediction of prognosis for individual patients remains untested. METHODS AND RESULTS: Between July 1, 1997 and September 30, 1999, 10 796 consecutive procedures were performed in a consortium of 8 hospitals. Predictors of in-hospital mortality were identified by use of multivariate logistic regression analysis. The final model was validated by use of the bootstrap technique. Additional validation was performed on an independent data set of 5863 consecutive procedures performed between October 1, 1999, and August 30, 2000. An additive risk-prediction score was developed by rounding coefficients of the logistic regression model to the closest half-integer, and a visual bedside tool for the prediction of individual patient prognosis was developed. In this patient population, the in-hospital mortality rate was 1.6%. Multivariate regression analysis identified acute myocardial infarction, cardiogenic shock, history of cardiac arrest, renal insufficiency, low ejection fraction, peripheral vascular disease, lesion characteristics, female sex, and advanced age as independent predictors of death. The model had excellent discrimination (area under the receiver operating characteristic curve, 0.90) and was accurate for prediction of mortality among different subgroups. Near-perfect correlation existed between calculated scores and observed mortality, with higher scores associated with higher mortality. CONCLUSIONS: Accurate predictions of individual patient risk of mortality associated with PCI can be achieved with a simple bedside tool. These predictions could be used during discussions of prognosis before and after PCI.

Age Factors↗
PubMed2001

Monoclonal antibody to single-stranded DNA: a potential tool for DNA repair studies.

Growing evidence suggests that DNA repair capacity is an important factor in cancer risk and is therefore essential to assess. Immunochemical assays are amenable to the detection of repair products in complex matrices, such as urine, facilitating noninvasive measurements, although diet and extra-DNA sources of lesion can confound interpretation. The production of single-stranded, lesion-containing DNA oligomers characterises nucleotide excision repair (NER) and hence defines the repair pathway from which a lesion may be derived. Herein we describe the characterisation of a monoclonal antibody which recognises guanine moieties in single-stranded DNA. Application of this antibody in ELISA, demonstrated such oligomers in supernatants from repair-proficient cells post-insult. Testing of urine samples from volunteers demonstrated a relationship between oligomer levels and two urinary DNA damage products, thymine dimers and 8-oxo-2'-deoxyguanosine, supporting our hypothesis that NER gives rise to lesion-containing oligomers which are specific targets for the investigation of DNA repair.

Animals↗
PubMed2001

Human casein kinase Idelta phosphorylation of human circadian clock proteins period 1 and 2.

Casein kinase Iepsilon (CKIepsilon), a central component of the circadian clock, interacts with and phosphorylates human period protein 1 (hPER1) [Keesler, G.A. et al. (2000) NeuroReport 5, 951-955]. A mutation in CKIepsilon causes a shortened circadian period in Syrian Golden hamster. We have now extended our previous studies to show that human casein kinase Idelta (hCKIdelta), the closest homologue to hCKIepsilon, associates with and phosphorylates hPER1 and causes protein instability. Furthermore, we observed that both hCKIdelta and hCKIepsilon phosphorylated and caused protein instability of human period 2 protein (hPER2). Immunohistochemical staining of rat brains demonstrates that CKIdelta protein is localized in the suprachiasmatic nuclei, the central location of the master clock. These results indicate that CKIdelta may play a role similar to CKIepsilon, suggesting that it may also be involved in regulating circadian rhythmicity by post-translation modification of mammalian clock proteins hPER1 and 2.

Animals↗