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Biomedical subjects

N Fernandez

Publications and source records attributed to N Fernandez.

At least 19 recordsLinked to original sources

Tolerogenic response: allorecognition pathways.

The induction of immune tolerance in transplant recipients has been sought for many years but only a fundamental understanding of the immunological mechanisms underlying graft rejection will allow manipulation of the anti-graft immune response. In general, acute rejection is better understood and treated than chronic rejection, as they occur through partially different mechanisms. It is now generally accepted that recognition of same-species, non-self antigens (allorecognition) occurs through at least two different mechanisms, the direct and indirect pathways. In the direct pathway, donor MHC molecules on the surface of donor antigen-presenting cells (APCs) are recognised directly by the recipient's T cells. This mechanism is so immediate that it seems to be primarily involved in acute graft rejection. Since APCs of donor origin are depleted with time a second mechanism, the indirect pathway, takes over to cause chronic rejection, in which foreign MHC molecules are internalised, partially digested and presented as peptides to recipient T cells. Nonetheless, a number of studies are only fully understood when a third proposed allorecognition mechanism is taken into account. This is the semi-indirect pathway, as discussed in this short report.

Antigen-Presenting Cells↗

Pancreas islet transplantation in patients with type 1 diabetes mellitus after kidney transplantation.

Diabetic patients with end-stage renal disease have a high mortality rate. A combined kidney-pancreas transplant is associated with greater life expectancy. Pancreas islet transplantation is an alternative involving a lower degree of morbidity. We present two patients, of 41 and 37 years of age, with a long history of diabetes mellitus (C-peptide negative), both with a previous kidney transplant, who had been treated with 22 and 28 U of insulin/d, respectively. Both patients had frequent episodes of unawareness hypoglycemia. Pancreatic islets were infused to a total of 7809 and 19,180 IE/kg, respectively. Basal posttransplant C peptide levels were 2.9 and 1.3 ng/mL. After the implant, one patient required occasional doses of insulin, and the other patient more than 50% reduced dose. After the first implant neither patient had any episodes of unawareness hypoglycemia. HbA1c at 4 months were 6.2% and 6.9%. There were no transplant-related complications.

Adult↗

Effect of c-reactive protein and interleukins blood levels in postsurgery arginine-enhanced enteral nutrition in head and neck cancer patients.

OBJECTIVE: It is known that the immune system is frequently affected in patients with head and neck cancer. Although immune dysfunction could be multifactorial, this immune system may be modulated by specific nutritional substrates, such as arginine. The aim of our study was to evaluate the effect of enteral nutrition supplemented with arginine on c-reactive protein (CRP), interleukin 6 (IL-6) and tumour necrosis factor (TNFalpha) in surgical head and neck cancer patients. DESIGN: Randomized trial. SETTING: Tertiary care. SUBJECTS: A population of 36 patients with oral and laryngeal cancer were enrolled. INTERVENTIONS: At surgery patients were randomly allocated to two groups: (a) patients receiving an enteral diet supplements with arginine and dietary fibre (group I, n=18); (b) patients receiving an isocaloric, isonitrogenous enteral formula (group II, n=18). Perioperatively and on postoperative day 5 the following parameters were evaluated: serum values of prealbumin, transferrin, albumin, total number of lymphocytes, interleukin 6, tumour necrosis factor alpha and c-reactive protein. RESULTS: The mean age was 59.6+/-10.9 y (two females/34 males). No significant intergroup differences in the trend of the three plasma proteins and weight were detected. CRP decreased in both groups (group I: 152.9+/-76.9 vs 68.9+/-82.5 mg/dl; P<0.05; and group II: 105.9+/-92 vs 43.6+/-59.1 mg/dl; P<0.05). Interleukin 6 did not change (group I: 16.3+/-12.3 vs 35.6+/-83.4 pg/ml; NS; and group II: 22.8+/-40 vs 9.9+/-17.7 pg/ml; NS). TNFalpha did not show any differences (group I: 4.6+/-1.6 vs 5.1+/-1.5 pg/ml; NS; and group II: 8.8+/-6.1 vs 5.8+/-1.7 pg/ml; NS). Lymphocytes increased in both groups (group I: 1405.6+/-517 vs 1634+/-529 x 10(6)/ml; P<0.05; and group II: 1355+/-696 vs 1561+/-541 x 10(6)/ml; P<0.05). CONCLUSIONS: Enhanced formula did not change IL6 and TNFalpha levels. Further studies are needed to determine whether route of nutrition or type of formula is the key in these patients.

Arginine↗

Evaluation of screening test for detection of antimicrobial residues in ewe milk.

The effects of preservatives (potassium dichromate and sodium azide), heat treatment (untreated and 82 degrees C/10 min), and lactation stage upon the response of the microbial tests (BRT AiM and Delvotest) utilized for the detection of residues of antimicrobial substances in ewe milk were examined. Milk samples were collected from the morning milking of 50 Manchega ewes every 2 wk, from 15 d postpartum until the end of lactation. A total of 2322 samples were analyzed by BRT AiM with prediffusion and Delvotest microbial tests. The specificity of preservative-free milk samples without heat treatment was high (96.3% for BRT and 97.7% for Delvotest), with results improving for those samples thermally treated at 82 degrees C/10 min (99.0% for BRT and 98.7% for Delvotest). Potassium dichromate produced a total inhibition of growth of Bacillus stearothermophilus with both methods. When acidiol was utilized, the specificity of the samples not treated thermally was lower compared with preservative-free milk samples for the BRT AiM (90.2%) and Delvotest (91.0%) methods, improving when the samples were thermally treated, both for BRT AiM (94.8%) and Delvotest (95.3%), given that the presence of the preservative increased the frequency of doubtful results. The lactation stage significantly affected the results of the methods, with a greater frequency of false-positive and doubtful cases toward the end of the cycle, especially in those samples preserved with acidiol. The greater selectivity in both methods was therefore obtained for preservative-free ewe milk samples with prior heat treatment taken at the beginning or in midlactation period.

Animals↗

Total homocysteine and cognitive deterioration in people with type 2 diabetes.

The aim of this study was to investigate the relationship between total homocysteine levels in people with Type 2 diabetes and cognitive status. Fifty patients from our diabetes unit (30 females/20 males) with diabetes were enrolled. All patients had fasting blood samples taken for measurement of cardiovascular risk factors; total cholesterol and triglyceride concentrations and other lipid fractions (lipoprotein (a), low density lipoprotein (LDL-cholesterol), high density lipoprotein (HDL-cholesterol)), glucose, HbA(1c) and homocysteine. 24-h urine collection was used to measure creatinine clearance and microalbuminuria. Vitamin B-12 and folate were measured to assess vitamin status. All diabetic patients were assessed for late complications and a Mini-Mental State Examination (MMSE) was performed. The patients were 64.6 (49-78) years old with body mass index (BMI) of 29.6 +/- 6.3 kg/m(2), and duration of diabetes of 8.9 +/- 6.7 years. A univariant correlation analysis was performed among cardiovascular risk factors and vitamins with total MMSE score. Total homocysteine was inverse by correlated with MMSE score (r=-0.38; P<0.05) of the other measures of cardiovascular risk, microalbuminuria showed an inverse correlation with MMSE score (r=-0.51:P<0.01). Lipoproteins, glucose control and vitamin status were not correlated MMSE score. In the multiple regression model only microalbuminuria remained in the model, showing a decrease of one point in the MMSE result with each milligram of microalbuminuria, adjusted for confounding factors. Cognitive status in type 2 diabetic was correlated with homocysteine levels and microalbuminuria, this last endothelial damage marker remaining as an independent risk factor of cognitive deterioration.

Aged↗

New process for simultaneous removal of nitrogen and sulphur under anaerobic conditions.

A granular activated carbon (GAC) anaerobic fluidised-bed reactor treating vinasse from an ethanol distillery of sugar beet molasses was operated for 90 days, the first 40 days of start-up followed by 50 days of operation at constant organic loading rate of 1.7g COD/Ld. The reactor showed good performance in terms of organic matter removal but an anomalous behaviour in terms of unusual high concentrations of molecular nitrogen in the biogas. The analysis of the different nitrogenous and sulphur compounds and the mass balances of these compounds in the liquid and gas phases clearly indicated an uncommon evolution of nitrogen and sulphur in the reactor. About 50% of the nitrogen entering the reactor as total Kjeldahl nitrogen (TKN) was removed from the liquid phase appearing as N2 in the gas phase. Simultaneously, only 20% of the S-SO4(2-) initially present in the influent appears as S-S2- in the effluent or S-H2S in the biogas, indicating that 80% of the sulphur is removed. This behaviour has not been reported previously in the literature. These observations may suggest a new anaerobic removal process of ammonia and sulphate according to an uncommon mechanism involving simultaneous anaerobic ammonium oxidation and sulphate reduction.

Anaerobiosis↗

[Role of dendritic cells in the modulation of innate effectors of immunity].

CD8+ cytotoxic T lymphocytes (CTL), specifically directed against tumor-associated antigens, can be used in immunotherapy as effector cells in order to induce antitumor immune response. However, natural killer (NK) cells, that belong to the innate immune system, might also play a role on the anti-tumoral immune response. Our data show that quiescent NK cells can be activated by direct cell contact with dendritic cells (CD). Such a NK cells activating ability places DC at the frontier between innate and cognate immunity and then may encourage their use in clinical trials designed to elicit both CTL and NK responses.

Animals↗

Titanium or polymethylmethacrylate in cervical disc surgery? A prospective study.

In 200 patients with either isolated protrusion of disc or with spondylosis a cervical discectomy in one or two levels was performed from a ventral approach. In 100 patients the removed disc was replaced with an implant of polymethylmethacrylat (PMMA). In 100 patients interbodyfusion was done with a titanium cage. Both groups were analysed in a prospective study. Clinical outcome was assessed after surgery. Results were similar in terms of complications and clinical outcome. As the PMMA surgery took longer and the costs of titanium are higher, there is no marked advantage of one implant material over the other.

Bone Substitutes↗

Luis Simarro Lacabra [1851-1921]: from Golgi to Cajal through Simarro, via Ranvier?

Knowledge of cerebral structure and function in its modern form can be traced to the neurone doctrine based largely on the work of Santiago Ramón y Cajal [1852-1934] and his lifelong exploitation of the Golgi method. Cajal openly acknowledged his debt to the neuropsychiatrist Luis Simarro Lacabra [1851-1921] who introduced him to the method in 1887, and recalled that the sight of the silver-impregnated nerve cells was the turning point which led him to abandon general anatomy and concentrate on neurohistology. Simarro, who dissipated his free time in trying to improve not only the scientific but also the political world around him, was able to produce exciting Golgi preparations of the cerebral cortex after he returned from voluntary exile in Paris from 1880 to 1885. Certainly it was there that he learned the methods of experimental histology from Louis-Antoine Ranvier [1835-1922] whose laboratory exercises, in the guise of lectures, he attended assiduously.

Chromates↗

Histamine H2 receptor desensitization: involvement of a select array of G protein-coupled receptor kinases.

The histamine H2 receptor (H2r) belongs to the heptahelical receptor family; upon agonist binding, members of this family activate a G protein and the downstream effector adenylyl cyclase. Like other G protein-coupled receptors, exposure of H2r to agonists produces a desensitization of the response. The present study focused on the desensitization mechanism of this receptor. Using transiently transfected COS-7 cells expressing tagged-H2r, the desensitization induced by amthamine, characterized by decreased cAMP production, was studied. Results show that the receptor was rapidly desensitized with a t(1/2) = 0.49 +/- 0.01 min. Because of the rapid nature of H2r desensitization, receptor phosphorylation was examined as a likely mechanism for signal attenuation. H2r desensitization was not affected by protein kinases A and C (PKA and PKC) inhibitors but was remarkably reduced by Zn(2+), an inhibitor of G protein-coupled receptor kinases (GRKs). Cotransfection experiments using tagged H2r and different GRKs (2, 3, 5, or 6), demonstrated that GRK2 and GRK3 were the most potent in augmenting desensitization, causing a reduction in the maximal response to amthamine and a decrease of the t(1/2) for desensitization, whereas GRK5 and GRK6 did not affect the signaling. Receptor phosphorylation correlates with desensitization for each GRK studied, whereas phosphorylation that is dependent on protein kinases A and C seemed irrelevant in receptor signal termination. These results indicate that in H2r-transfected COS-7 cells, exposure to an agonist caused desensitization controlled by H2r phosphorylation via GRK2 and GRK3.

Animals↗

Fluorescence recovery after photobleaching reveals that LPS rapidly transfers from CD14 to hsp70 and hsp90 on the cell membrane.

Although CD14 has been implicated in the immune recognition of bacterial lipopolysaccharide (LPS) from Gram-negative bacteria and also peptidoglycan (PGN) and lipoteichoic acid (LTA) from the outer cell wall of Gram-positive bacteria, accumulating evidence has suggested the possible existence of other functional receptor(s). In this study, we have used fluorescence recovery after photobleaching (FRAP) in order to get the first dynamic picture of the innate recognition of bacteria. We have found that the diffusion coefficient of CD14 remains unaffected after LPS ligation and that the diffusion coefficients of FITC-LPS and FITC-LTA bound to cells differ from that of CD14. Furthermore, FITC-LPS/LTA rapidly become immobile when bound to cells, suggesting that FITC-LPS/LTA must briefly associate with CD14 in the initial attachment process and rapidly move on to an immobile receptor or to a complex of receptors. Further FRAP experiments revealed that heat shock protein 70 (hsp70) and hsp90 are immobile in cell membranes, and antibodies against them were found to block the transfer of LPS to the immobile receptor and to inhibit interleukin 6 production upon LPS stimulation. These experiments indicated that LPS transfers from CD14 to hsp70 and hsp90, which may be part of an LPS/LTA multimeric receptor complex. Thus, hsps are implicated as mediators of the innate activation by bacteria.

Animals↗

Bovine somatotropin dose titration in lactating dairy ewes. 3. Treatment interval.

Seventy-four lactating dairy ewes were injected with recombinant bovine somatotropin (bST; sometribove) in a sustained-release formulation. Ewes received 0, 80, 160, or 240 mg of bST/14 d at the end of 2, 4, and 6 wk postlambing, after which injections were withheld for a 28-d period. Response of milk production to bST presented a positive linear contrast and a negative quadratic contrast. After the final injection of bST (d 0), an increase in daily milk production was observed until d +9. A continuous decrease followed with milk production returned to control levels on d +11, +18, and +20, for 80, 160, and 240 mg of bST/14 d. Milk protein content decreased gradually until d +8 before it returned to control levels on d +12, +14 and +14, for 80, 160, and 240 mg of bST/14 d. Levels of bST and IGF-I in plasma presented positive and highly significant linear contrasts and negative quadratics which were significant only for bST. Relative to the evolution of milk production, the evolution of IGF-I levels in plasma was more similar than that of bST, although the correlation of each measure with milk production was high and highly significant. It was concluded that the period between successive injections should be shorter the lower the dose employed; however, a 14-d period seemed to correspond correctly for the dosages and hormone formulation tested.

Animals↗

Extended scope of nursing practice: a multicentre randomised controlled trial of appropriately trained nurses and pre-registration house officers in pre-operative assessment in elective general surgery.

OBJECTIVES: (1) To determine whether pre-operative assessment carried out by an appropriately trained nurse (ATN) is equivalent in quality to that carried out by a pre-registration house officer (PRHO). (2) To assess whether pre-assessments carried out by ATNs and PRHOs are equivalent in terms of cost. (3) To determine whether assessments carried out by ATNs are acceptable to patients. (4) To investigate the quality of communication between senior medical staff and ATNs. DESIGN: The study design was principally a prospective randomised equivalence trial but was accompanied by additional qualitative assessment of patient and staff perceptions, and an economic evaluation. SETTING: The study was carried out at four NHS hospitals, three of which were teaching hospitals, in three NHS Trusts in Southampton, Sheffield and Doncaster. SUBJECTS: All patients attending at one site for assessment prior to general anaesthetic for elective general, vascular, urological or breast surgery were potentially included in the study. Of 1907 patients who were randomised, 1874 completed the study with a full evaluation. INTERVENTIONS: The intervention consisted of a pre-operative assessment carried out by either an ATN or a PRHO. Of the patients who completed the study with a full evaluation, 926 patients were randomised to the PRHO arm of the trial and 948 to the ATN arm. Three ATNs took part in the study, one from each centre, together with a total of 87 PRHOs. MAIN OUTCOME MEASURES: Immediately following the initial assessment of a patient by a PRHO or an ATN, one of a number of clinical research fellows, all specialist registrars in anaesthetics, repeated the assessment and recorded it on a study form, together with a list of investigations required. The clinical research fellow then evaluated the competency of the initial assessor by comparing the quality of their assessment with their own. Any deficiencies in ordering of investigations and referral to other specialities were met in order to maximise patient care. Three areas of ATN and PRHO performance were judged separately, history taking, examination and ordering of tests, and each was graded into one of four categories, the most important of which was under-assessment, which would possibly have affected peri-operative management. In the case of ordering of tests, it was possible to have both over- and under-assessed a patient on different tests. RESULTS: The pre-operative assessments carried out by the ATNs were essentially equivalent to those performed by the PRHOs in terms of under-assessment that might possibly have affected peri-operative management, although there was variation between the ATNs in terms of the quality of history taking. This may be related to the low number of patients seen at one study site. PRHOs ordered significantly more unnecessary tests than the ATNs. The substitution of ATNs for PRHOs was calculated to be cost neutral. The results of the qualitative assessment showed that the use of ATNs for pre-operative assessment was acceptable to patients; however, there was no evidence that communication between senior medical staff and those carrying out pre-operative assessments was improved by their introduction. CONCLUSIONS: This study demonstrated no reason to inhibit the development of fully nurse-led pre-operative assessment, provided that the nurses are appropriately trained and maintain sufficient workload to retain skills. CONCLUSIONS--IMPLICATIONS FOR THE HEALTH SERVICE: ATNs provide an acceptable and efficient alternative to PRHOs for the purposes of routine pre-operative assessment. Consideration will have to be given, however, to the positions of these nurses within the surgical team, and also to their career structure. CONCLUSIONS--RECOMMENDATIONS FOR FUTURE RESEARCH: Further research is needed in the following areas: (1) the extent and type of training needed for nurses undertaking the pre-operative assessment role; (2) the use, costs and benefits of routine pre-operative testing.

Clinical Competence↗

Detection limits of beta-lactam antibiotics in ewe milk by penzym enzymatic test.

The Penzym is an enzymatic test widely used for the detection of beta-lactam antibiotic residuals in milk. It is a specific method with good sensitivity to this group of antibiotics and enables results to be obtained within a short time. In the present work, the detection limits of 10 beta-lactam antibiotics were determined in ewe milk, given the lack of previous studies of the Penzym test in ovine milk. For each antibiotic, eight concentrations were tested on 20 ewe milk samples proceeding from individual ewes (160 analyses per drug). The limits of the Penzym test were determined by means of logistic regression models, as follows: 5 microg/kg amoxicillin, 4 microg/kg ampicillin, 33 microg/kg cloxacillin, 3 microg/kg penicillin "G," 43 microg/kg cephadroxil. 10 microg/kg cephalosporin "C," 16 microg/kg cephalexin, 900 microg/kg cephoperazone, 120 microg/kg Ceftiofur, and 77 microg/kg cephuroxime. The percentages of positive results for those antibiotics at the maximum residue limit (MRL) concentration established by the European Union (EU) were: 100% (penicillin "G"), 93.3% (ampicillin), 93.3% (cloxacillin), 56.7% (Ceftiofur), and 56.7% (amoxicillin).

Animals↗

Simultaneous organic nitrogen and sulfate removal in an anaerobic GAC fluidised bed reactor.

A granular activated carbon (GAC) anaerobic fluidised bed reactor treating vinasse from an ethanol distillery of sugar beet molasses was operated for 250 days under three different organic loading rates. The reactor showed good performance in terms of organic matter removal and methane production but an anomalous behaviour in terms of unusual high concentrations of molecular nitrogen and low concentration of hydrogen sulphide in the biogas. The analysis of the different nitrogenous and sulphur compounds and the mass balances of these species in the liquid and gas phases clearly indicated an uncommon evolution of nitrogen and sulphur in the reactor. Up to 55% of the TKN and up to 80% of the sulphur disappear in the liquid phase. This is the opposite to any previously reported results in the bibliography. The new postulated anaerobic process of ammonia and sulphate removal seems to follow the mechanism: SO4 = +2 NH4+-->S + N2 + 4H2O (delta G degree = -47.8 kJ/mol).

Alcoholic Beverages↗

Atypical protein kinase Czeta suppresses migration of mouse melanoma cells.

Mouse melanoma B16 F1 cells cultured in RPMI 1640 supplemented with the melanin precursors tyrosine and phenylalanine display increased melanin levels and elevated migration while down-regulating protein kinase C (PKC)zeta to low levels. Although control experiments rule out a direct role by melanin, PKCzeta down-regulation is shown to be a critical determinant of cell migration. Transfection of high-motility cells with either wild-type PKCzeta or its regulatory domain suppresses migration. Known to bind to the regulatory domain of PKCzeta, the proapoptotic protein prostate apoptosis response-4 (Par-4) coimmunoprecipitates with PKCzeta as a 47-kDa protein. Transfection of Par-4 (or its leucine zipper element) further suppresses migration of low-motility cells (which express high levels of PKCzeta), whereas high-motility cells (which express low levels of PKCzeta) are unaffected by Par-4 overexpression. It is proposed that in nonmetastatic cells, the PKCzeta Par-4 complex provides a brake on migration that is released by melanin precursors that initiate PKCzeta down-regulation. Elevation of PKCzeta in melanoma cells, or preventing its down-regulation through the dietary restriction of tyrosine and phenylalanine, may therefore control metastatic behavior.

Animals↗

Lipopolysaccharide (LPS) labeled with Alexa 488 hydrazide as a novel probe for LPS binding studies.

BACKGROUND: Lipopolysaccharide (LPS) comprises the outer cell wall of all gram-negative bacteria. It consists of an oligosaccharide core and lipid A. All LPS-induced biological responses are lipid A-dependent. Once released, LPS triggers a host systemic inflammatory response that leads to septic shock. Binding studies have helped to reveal some of the molecular interactions behind septic shock. Such studies have employed methods of labeling bacterial LPS with either radiochemicals or fluorescent dyes. Poor labeling of the LPS has resulted in the use of high concentrations of LPS in order to detect its binding. METHODS: In this study, we have devised a new methodology for labeling LPS, using hydrazide and galactose oxidase in order to oxidize galactose residues to aldehyde groups in the oligosaccharide core of the LPS. RESULTS: We have managed to generate a conjugate that is highly fluorescent (LPS-to-Alexa 488 labeling ratio of 1:5) and biologically active. CONCLUSIONS: For the first time, this probe has enabled us to detect LPS binding even at pg/ml concentrations. Using this methodology, any Alexa-hydrazide dye can be conjugated to LPS, providing us with novel probes for imaging studies.

Animals↗