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Biomedical subjects

A Hassan

Publications and source records attributed to A Hassan.

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

Evaluation of a new enzyme immunoassay for the detection of Helicobacter pylori in stool specimens.

H. pylori infects the gastric mucosa and causes many digestive disorders such as peptic ulcer, chronic gastritis and gastric cancer. H. pylori infection relates neither to functional health status, nor to intensity of dyspepsia. There is evidence that in most patients with H. pylori positive functional dyspepsia do not improve with eradication of the organism.This study evaluated the diagnostic accuracy of HpSA by determining the sensitivity and specificity of the stool antigen test in predicting successful eradication during and after anti microbial therapy. The work was conducted on patients who underwent upper gastrointestinal endoscopy at Al-Azhar University hospitals. Fifty patients (34 male & 16 female) with dyspepsia were selected, the exclusion criteria included use of antibiotics and proton pump inhibitors up to one month before the study. All cases were submitted to, full history, general and local examination and upper gastrointestinal endoscopy. Biopsies were taken from the antrum and body of the stomach for rapid urease test and histopathology. Stool samples were taken to detect H. pylori stool antigen. Positive patients received eradication treatment for one month and H. pylori status was re-determined by rapid urease test, histological examination and HpSA test one month later. H. pylori was detected by rapid urease test in 29 (58%) dyspeptic patient by histology in 26(52%) dyspeptic patient, while H. pylori was detected by HpSA immunoassay in 16 (32%) dyspeptic patient. The sensitivity and specificity of HpSA were 57.7% and 95.8% respectively. After successful eradication of H. pylori, reassessment by rapid urease test and histology revealed curative rate of 86.2% and 84.6% respectively, while HpSA immunoassay revealed curative rate 75%. Based on these results, the HpSA immunoassay gave sensitivity (75%) and specificity (100%). The H. pylori stool test represents an accurate and novel non-invasive concept for diagnosis of infection and can be used for daily routine in clinical practice. HpSA is a promising non-invasive test for diagnosis of H. pylori infection but may be hampered by low patient acceptability. So, HpSA is a valuable test in the pre-and post eradication assessment of infection. HpSA can be profitably employed in the primary diagnosis of H. pylori infection. This non invasive test could be very useful in investigating dyspeptic young patients. Also, it could be used profitably in epidemiological studies to determine the prevalence of H. pylori infection in the asymptomatic subjects in different communities.

Adult↗
PubMed2002

Non-myeloablative stem cell transplantation for congenital immunodeficiencies.

Allogeneic haematopoietic stem cell transplantation (HSCT) can be a highly successful treatment option for individuals with congenital immunodeficiency states. The strategy for HSCT is varied but in cases where there is preservation of residual T cell function, conditioning regimes have been used and have been based around a combination of busulphan and cyclophosphamide with or without serotherapy. In patients with coexisting organ damage this has resulted in significant morbidity and mortality. We have therefore used a low-intensity conditioning regime for transplantation in this group of immunodeficiency patients. Twenty-one patients with a variety of different immunodeficiencies were treated using the following conditioning regimes: (1) fludarabine/melphalan/ATG or Campath 1H (n=16), (2) fludarabine/cyclophosphamide/Campath 1H (n=1), (3) TBI/CyA/MMF (n=1), (4) fludarabine/melphalan/busulphan/ATG (n=3). In 13 cases matched (n=9) and 1 Ag mismatched (n=4) unrelated donors were used and in eight cases transplants from matched siblings (n=4), 1 Ag mismatched sibling (n=1), matched parent (n=1) and haploidentical parents (n=3) were performed. At a median follow-up of 13 months, 19 of 21 (90%) patients were still alive following the transplant procedure. Despite a T cell replete graft and the use of unrelated donor grafts in the majority of patients studied there was no evidence of significant organ disease. Immune reconstitution in terms of CD3+ and CD4+ T cell recovery and function was equivalent in comparison with a historical cohort. We believe that this low-intensity approach has significant implications for transplantation of individuals with immunodeficiency states with established organ disease.

Adolescent↗
PubMed2002

Acute and chronic regulation of pituitary receptors for vasopressin and corticotropin releasing hormone.

At least two hypothalamic peptides, corticotropin releasing hormone (CRH) and vasopressin (VP), are important in regulating adrenocorticotropin (ACTH) release from the anterior pituitary. Both are secreted in a pulsatile manner and stimulate ACTH secretion by interacting with G protein-coupled receptors (GPCRs), namely the type 1 CRH receptor and V1b receptor, respectively. Repeated or prolonged stimulation with either peptide can cause reduced ACTH responsiveness or desensitisation, both in vivo and in vitro. Desensitisation of perifused sheep anterior pituitary cells to VP was found to be rapid and occurred following treatment with 5 nM VP for 5 min. This is within the range of concentrations and durations of VP pulses seen in sheep portal blood during acute stress. In contrast, significant desensitisation of the ACTH response to CRH required pre-treatment for longer than 25 min with a CRH concentration of 1 nM, suggesting that endogenous pulses may not elicit desensitisation. Although rapid GPCR desensitisation involves uncoupling of receptors from their G proteins, commonly mediated by receptor phosphorylation, and internalisation of receptors, desensitisation of neither the CRH nor VP receptor was mediated by PKA or PKC, respectively. Desensitisation of the response to VP was found to be dependent upon receptor internalisation, and resensitisation could be delayed by treatment with a protein phosphatase 2B inhibitor. The rapid kinetics of desensitisation of the ACTH response to VP suggest that this process is important in regulating the response to acute rather than chronic stress. If, as has been suggested, CRH acts in a permissive way to set corticotrope gain, desensitisation to CRH could also be important in long term regulation of ACTH secretion.

Adrenal Glands↗
PubMed2002

Cerebral metabolic changes associated with Lyme disease.

There are no positron emission tomography (PET) studies reported in the literature with regards to brain metabolism and function in patients with Lyme disease. These patients frequently present with various neurological symptoms, including memory problems. We used [(18)F]fluorodeoxyglucose (FDG) PET to determine the metabolic landscape in 23 patients with Lyme disease. Images were evaluated for cortical and subcortical abnormalities by two experienced reviewers blinded to the clinical information. The most striking finding was hypometabolism in the temporal lobes in 17/23 (74%) patients. Of these, 12 had bilateral temporal lobe hypometabolism, two had left temporal lobe, and three had right temporal lobe hypometabolism. Seven of the patients with temporal lobe hypometabolism had diffuse cortical hypometabolism that included the frontal and parietal lobes. Lyme disease appears to have two primary patterns of brain involvement on FDG PET scans, specific temporal lobe hypometabolism or a diffuse cortical hypometabolism. The involvement of the temporal lobes in both patterns is likely associated with the memory disturbances described in many of these patients. Although there was no clear diagnostic pattern, and many of the defects were mild, FDG PET imaging may provide important information regarding the areas of the brain affected in patients with neurological symptoms associated with Lyme disease.

Adolescent↗
PubMed2002

Angiotensin converting enzyme insertion/deletion genotype is associated with leukoaraiosis in lacunar syndromes.

OBJECTIVES: Pathological and clinical data suggest that patients presenting with ischaemic lacunar syndromes may be a heterogenous group. Those with isolated lacunar infarction are thought to have localised atherosclerosis whereas in those with coexisting leukoaraiois a distinct diffuse small vessel vasculopathy may be the predominant underlying pathology. The ACE insertion/deletion (I/D) polymorphism is an important candidate gene in ischaemic cerebrovascular disease but, where lacunar stroke specifically has been examined, there have been discrepant reports concerning a possible association. It was hypothesised that the influence of the ACE gene may be different among the two subgroups of ischaemic lacunar stroke reflecting the heterogeneity of the small vessel disease phenotype. METHODS: Eighty four consecutive patients presenting with classic lacunar syndromes were studied. All had acute cranial CT to exclude primary intracerebral haemorrhage and these were subsequently assessed for the presence and extent of leukoaraiosis. All patients were genotyped for the ACE insertion/deletion polymorphism. RESULTS: There was a significant difference in the distribution of ACE genotype with the DD genotype occurring more often in patients with leukoaraiosis and the II and ID genotypes occurring more often among those in whom this was absent (chi(2)=9.06, p=0.01). In a logistic regression model the ACE DD genotype remained as an independent predictor for the presence of leukoaraiosis (p=0.02) in patients presenting with classic lacunar syndromes. CONCLUSION: This study supports the hypothesis that there may be different types of small vessel disease in patients with classic lacunar syndromes and that the influence of the ACE DD genotype may be relevant in mediating the diffuse form of vessel injury.

Aged↗
PubMed2001

Atrial natriuretic peptide gene G664A polymorphism and the risk of ischemic cerebrovascular disease.

The atrial natriuretic peptide (ANP) gene may underlie stroke susceptibility and sensitivity to cerebral ischemia in an animal model of stroke. The authors investigate its role in humans by genotyping a polymorphism (G664A) in 436 patients with ischemic cerebrovascular disease and 295 community control subjects. The frequency of this variant was similar in both groups and across the different stroke subtypes. The ANP gene G664A polymorphism is therefore unlikely to be an important risk factor for ischemic stroke in this population.

Aged↗
PubMed2001

High-frequency EPR study of a new mononuclear manganese(III) complex:. [(terpy)Mn(N3)3] (terpy = 2,2':6',2''-terpyridine).

The isolation and structural characterization of [(terpy)Mn(III)(N3)3], complex 1, is reported (terpy = 2,2':6',2' '-terpyridine). Complex 1, a product of the reaction between the mixed-valence dimer [(terpy)(H2O)Mn(III)(O)2Mn(IV)(OH2)(terpy)](NO3)3 and NaN3, crystallizes in a triclinic system, space group P1, a = 8.480(1) A, b = 8.9007(2) A, c = 12.109(2) A, alpha = 93.79(1) degrees, beta = 103.17(1) degrees, gamma = 103.11(1) degrees, and Z = 2. Complex 1 exhibits a Jahn-Teller distortion of the octahedron characteristic of a six-coordinated high-spin Mn(III). A vibrational spectroscopic study was performed. The nu(asym)(N3) mode of complex 1 appears in the IR as a strong band at 2035 cm(-1) with a less intense feature at 2072 cm(-1), and in the FT-Raman as a strong band at 2071 cm(-1) with a weaker broad band at 2046 cm(-1). The electronic properties of complex 1 were investigated using a high-field and high-frequency EPR study (190-475 GHz). The different spin Hamiltonian parameters have been determined (D = -3.29 (+/-0.01) cm(-1), E = 0.48 (+/-0.01) cm(-1), E '= 0.53 (+/-0.01) cm(-1), g(x) = 2.00 (+/-0.005), g(y) = 1.98 (+/-0.005), g(z) = 2.01 (+/-0.005)). These parameters are in agreement with the geometry of complex 1 observed in the crystal structure, a D < 0 related to the elongated distortion, and a value of E/D close to 0.2 as expected from the highly distorted octahedron. The two values of the E-parameter are explained by the presence of two slightly different structural forms of complex 1 in the crystal lattice. A second hypothesis was explored to explain the experimental data. The calculation for the simulation was done taking into account that the g and D tensors are not collinear due to the low symmetry of complex 1. In that case, the spin Hamiltonian parameters found are D = -3.29 (+/-0.01) cm(-1), E = 0.51 (+/-0.01) cm(-1), g(x) = 2.00 (+/-0.005), g(y) = 1.98 (+/-0.005), and g(z) = 2.01 (+/-0.005).

Crystallography, X-Ray↗
PubMed2001

Double-blind, placebo-controlled cross-over study of oral pilocarpine for the prevention of chemotherapy-induced oral mucositis in adult patients with cancer.

This study aimed to investigate the effect of oral pilocarpine (OP) in reducing the incidence of chemotherapy-induced oral mucositis. 32 adult cancer patients completed a total of 82 courses of chemotherapy in which either OP or placebo was given prophylactically in a double-blind cross-over design to prevent mucositis. Mucositis was documented in 20 out of 41 courses in which patients were given placebo, whereas mucositis was documented in only six out of 41 courses when patients were given OP (P<0.005). OP treatment was found to significantly reduce the mucositis score when assessed by the method of Donnelly and colleagues (Donnelly JP, Muus P, Schattenberg A, De Witte T, Horrevorts A, De Pauw BE. Bone Marrow Transplant 1992, 9, 409-413). Using this score, all patients scored a total of 52 when they were given the placebo versus eleven when they were treated with OP (P<0.001). A similar reduction in mucositis score was noticed using the World Health Organization (WHO) mucositis score; the total patient score was 25 for the placebo-treated group versus 6 for the OP group (P<0.001). We therefore conclude that oral pilocarpine is highly effective in the prevention of oral mucositis when given prophylactically to adult patients receiving a variety of cancer chemotherapy regimens.

Adult↗
PubMed2001

Secondary peritonitis: severity of disease and activation of peritoneal cells.

OBJECTIVE: To compare the degree of the inflammatory response of human peritoneum with the severity of peritonitis. DESIGN: Clinical laboratory study. SETTING: University hospital, Germany. SUBJECTS: 15 patients with diffuse secondary peritonitis and 5 having conventional cholecystectomy (controls) had peritoneal specimens taken from the site of incision. MAIN OUTCOME MEASURES: Correlation between presence of indicators of the inflammatory response: interleukin 1 (IL-1), interleukin 6 (IL-6), intercellular adhesion molecule-1 (ICAM-1), antibacterial protein (defensin 3 reflecting the activation of granulocytes), the antibody clone HAM 56 (for detection of local macrophages), and antibodies against macrophage migration inhibiting factor (MIF)-related proteins 8 and 14 (MRP 8 and 14), and clinical state evaluated by the Mannheim Peritonitis Index (MPI), the Peritonitis Index Altona II (PIA II) and the Acute Physiology Score (APS). C-reactive protein (CRP) concentrations were measured preoperatively in the serum. RESULTS: Expression of MRP 8 and 14, HAM 56, and defensin 3 was significantly higher in patients with peritonitis than in controls (p < 0.05). Expression of IL-1 and IL-6 was almost undetectable. ICAM-1 expression correlated significantly with phagocytic activation. There was no correlation between clinical scores, CRP, and immunohistochemically detectable variables. CONCLUSION: The pattern of peritoneal inflammatory reactions is relatively uniform and does not correlate with the clinical grading of severity.

Adult↗
PubMed2001

Directional coronary atherectomy: the Vienna experience.

BACKGROUND: Several multicenter trials have shown excellent results for directional coronary atherectomy (DCA) in a selected patient cohort. To prove the applicability of this method in daily clinical routine and a nonselected patient cohort, we analyzed 46 consecutive cases performed at our catheterization lab. METHODS: DCA was performed as a routine procedure in 45 suitable patients. Balloon dilatation or stent implantation postprocedure was accomplished only in case of unsatisfactory results. Quantitative coronary angiography was achieved pre- and postprocedure as well as at 6-month follow-up. RESULTS: Optimal atherectomy < 20% residual stenosis was reached in 24 (52%) of 46 target lesions and a residual stenosis < 50% in 46 (100%) lesions. Procedure-related complications occurred in three (6%) patients (one major complication, death, < 24 hours, 2%; two minor complications, pseudoaneurysm, 4%). The 6-month angiographic follow-up revealed a binary restenosis rate of 29% (n = 11). Ten out of 11 restenotic lesions required revascularization. When patients were stratified in two groups according to their preprocedural minimal lumen diameter (MLD), this parameter proved to be a very strong predictor of outcome. The percentage of restenosis was significantly higher in patients with an MLD > 1.60 mm compared to patients with a smaller MLD (54% vs 19.3%; P < 0.0001). Reference vessel diameter preprocedure did not differ significantly. CONCLUSIONS: Our study demonstrated that DCA is a suitable technique for the daily clinical routine, as the rates of complications and restenosis were similar to that in a highly selective patient cohort. Additionally, our study showed that patient selection should include preprocedural analysis of MLD in order to achieve optimal results. Therefore, atherectomy yielded comparable results to other conventional techniques and may be used instead of or in combination with them.

Aged↗
PubMed2001

Volume of activation of the Hering-Breuer inflation reflex in the newborn infant.

Although the Hering-Breuer inflation reflex (HBIR) is active within tidal breathing range in the neonatal period, there is no information regarding whether a critical volume has to be exceeded before any effect can be observed. To explore this, effects of multiple airway occlusions on inspiratory and expiratory timing were measured throughout tidal breathing range using a face mask and shutter system. In 20 of the 22 healthy infants studied, there was significant shortening of inspiration because the volume at which occlusion occurred rose from functional residual capacity (FRC) to end-inspiratory volume [14.9% reduction in inspiratory time (per ml/kg increase in lung volume at occlusion)]. All infants showed a significant increase in expiratory time [17.1% increase (per ml/kg increase in lung volume at occlusion)]. Polynomial regression analyses revealed a progressive increase in strength of HBIR from FRC to approximately 4 ml/kg above FRC. Eighteen infants showed no further shortening of inspiratory time and 10 infants no further lengthening of expiratory time with increasing occlusion volumes, indicating maximal stimulation of the reflex had been achieved. There was a significant relationship between strength of HBIR and respiratory rate, suggesting that HBIR modifies the breathing pattern in the neonatal period.

Humans↗
PubMed2001

Numerical simulation of the turbulent flow field distal to an aortic heart valve.

A numerical technique is described which simulates the turbulent flow through a aortic Jellyfish valve, for two volumetric flow rates of 15 and 26 l/min representing peak systole flow. The steady incompressible Navier-Stokes equations written in three-dimensional (3-D) format are solved iteratively using a computational fluid dynamics code (Bio-FL). The numerical results show that the flow at the edge of the membrane of the valve splits into two nearly symmetrical jets with similar phenomenological features. Moreover, the 3-D flow simulations indicate the existence of two vortices in the immediate vicinity of the valve ring. Although these vortices are attenuated rapidly downstream by diffusion, they can have an adverse effect on erythrocytes and active platelets. It is also shown that elevated shear stresses occur in the vicinity of the upstream surface of the open occluder. In general. the numerical predictions compare well with the experimental measurements made at various locations downstream of the valve. The locations and the values of maximum velocity and shear stress, as well as width and length of re-circulation regions, are correctly predicted.

Blood Flow Velocity↗
PubMed2001

The relationship of AIS to peak virtual power.

All injuries require an expenditure of energy. Here it is postulated that injury severity is proportional to Peak Virtual Power (PVP). PVP is compared to AIS scores for frontal impact with belted drivers, for all types of injuries and all body regions, from the Co-operative Crash Injury Study (CCIS) and NASS-CDS databases. The excellent correlations obtained show that the AIS score is linearly proportional to Peak Virtual Power, which is proportional to delta V3 for restrained occupants, and delta V2 for unrestrained occupants. Therefore, although phenomenological, AIS appears to measure a physical quantity. It is concluded that there appears to be a "Master Curve" of AIS versus mean delta V for car occupants, implying that the amount of power for a given injury level is a constant, irrespective of injury type. There appear to be significant differences between the AIS scores for abdominal injuries between CCIS and NASS-CDS, and detailed case studies should be conducted to resolve the differences.

Abbreviated Injury Scale↗
PubMed2000

Mutagenesis studies on the iron binding ligands of clavaminic acid synthase.

Mutagenesis studies on conserved histidine residues identified as possible metal binding ligands in clavaminic acid synthase isozyme 2 were consistent with His-145 and His-280 acting as iron ligands, in support of crystallographic and previous mutagenesis studies. Mutagenesis of the four cysteines and a glutamine residue, conserved in both clavaminic acid synthase isozymes 1 and 2, demonstrated that none of these residues is essential for activity.

Amino Acid Substitution↗
PubMed2000

Pre-existing arterial remodeling is associated with in-hospital and late adverse cardiac events after coronary interventions in patients with stable angina pectoris.

OBJECTIVES: The goal of this study was to investigate the association between the atherosclerotic arterial remodeling and the incidence of cardiac events after coronary interventions in patients with stable angina. BACKGROUND: The local mode of de novo atherosclerotic remodeling is associated with plaque vulnerability and clinical symptoms. It may, therefore, reflect plaque morphology influencing the long-term outcome after coronary interventions. METHODS: Quantitative angiography and intravascular ultrasound were obtained in 244 patients with stable angina before and after single-vessel revascularization. On the basis of the lesion and the reference segment vessel size, patients were categorized into three groups (adaptive [AR], constrictive [CR] and intermediate [IR] remodeling). The lesion was analyzed for lumen, total vessel and plaque areas. Clinical follow-up was obtained at a mean period of 7.7+/-3.7 months. RESULTS: Patients with CR had a higher rate of in-hospital complications (10.9% vs. 2.9% and 2.7% in group CR vs. AR and IR, p = 0.035). In contrast, patients with AR had the highest rate of major adverse cardiac events (MACE) (44.3% vs. 25.5% in IR and 28.1% in CR, p = 0.024) with a predominance of revascularization at follow-up. Both target lesion restenosis (p = 0.036) and nontarget lesion de novo stenosis (p = 0.007) occurred more frequently in this group. Adaptive remodeling was a significant predictor of MACE in multivariate analysis. CONCLUSIONS: Adaptive remodeling is associated with a higher rate of MACE, target lesion restenosis and nontarget de novo stenosis. This finding may be due to differential responses of the adaptively remodeled vessel to revascularization and a generally accelerated course of systemic atherosclerosis.

Aged↗
PubMed2000

Nonmyeloablative stem cell transplantation for congenital immunodeficiencies.

The optimal approach for stem cell transplantation in children with immunodeficiency has yet to be determined. Conditioning therapy is necessary for reliable engraftment and full immune reconstitution; however, the beneficial effect of cytoreductive conditioning is counterbalanced by increased short- and long-term treatment-related toxicity. Whether bone marrow transplantation with a nonmyeloablative preparative regimen was sufficient for the establishment of donor immune reconstitution, with the resultant correction of disease phenotype, was investigated. Eight patients with severe immunodeficiency states underwent T-cell replete bone marrow transplantation from a human leukocyte antigen-matched unrelated (n = 6) or sibling (n = 2) donor with nonmyeloablative conditioning using a fludarabine-melphalan-anti-lymphocyte globulin-based regimen. All patients had severe organ dysfunction that precluded transplantation with conventional conditioning. All patients were engrafted with predominantly donor hematopoiesis, and the duration of neutropenia was brief. Significant acute graft-versus-host disease (GVHD) did not develop, but one patient had limited chronic GVHD. One patient died of disease recurrence, and 3 have stable, mixed chimerism. At a median follow-up of 1 year, all patients have had good recovery of CD3(+) T-cell numbers, and 6 of 7 evaluable patients have normal phytohemagglutinin stimulation indices. The rate of immune reconstitution is comparable with that of historical controls undergoing standard myeloablative protocols. Two patients with CD40 ligand deficiency now show significant expression, and a patient with adenosine deaminase deficiency has improved deoxy adenosine triphosphate metabolites. In summary, it has been demonstrated that nonmyeloablative stem cell transplantation permits rapid engraftment from both sibling and unrelated donors with minimal toxicity even in the presence of severe organ dysfunction. If long-term immune reconstitution of patients treated with this protocol is demonstrated, it is believed this approach might offer significant advantages compared with standard protocols by combining adequate immune reconstitution with reduced short- and long-term toxicity. (Blood. 2000;96:1239-1246)

Child↗
PubMed2000

Selective regional myocardial infiltration by the percutaneous coronary venous route: A novel technique for local drug delivery.

Recent advances in the treatment of heart disease, in particular cardiovascular gene therapy and therapeutic angiogenesis, highlight the need for efficient and practical local delivery methods for the heart. We assessed the feasibility of percutaneous selective coronary venous cannulation and injection as a novel approach to local myocardial drug delivery. In anesthetized swine, the coronary sinus was cannulated percutaneously and a balloon-tipped catheter advanced to the anterior interventricular vein (AIV) or middle cardiac vein (MCV). During balloon occlusion, venous injection of radiographic contrast caused regional infiltration of targeted myocardial regions. Complete AIV occlusion had no impact on LAD flow parameters. Videodensitometric analysis following venous injection showed that radiographic contrast persisted for at least 30 min. Selective regional myocardial infiltration is feasible by this approach, targeting selected myocardial beds, including the apex, anterior wall, septum, and inferoposterior wall. This novel technique has potential application for local myocardial drug or growth factor delivery. Cathet. Cardiovasc. Intervent. 51:358-363, 2000.

Animals↗