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Biomedical subjects

H Hassan

Publications and source records attributed to H Hassan.

At least 19 recordsLinked to original sources
PubMed2006

Analysis of endoscopic ultrasound elastography used for characterisation and differentiation of benign and malignant lymph nodes.

PURPOSE: Ultrasound elastography is a new imaging procedure which allows the reconstruction of elasticity distribution by characterising the difference of hardness between pathological and normal tissue. MATERIALS AND METHODS: The aim of our study was to apply real-time elastography during endoscopic ultrasound (EUS) examinations and to consequently characterise benign versus malignant lymph nodes. The pattern of real-time EUS elastography images was compared with the conventional EUS aspects of lymph nodes and with the final diagnosis obtained by EUS-FNA cytology analysis and/or by surgical pathology. RESULTS: Patients diagnosed by EUS with cervical, mediastinal or abdominal lymph nodes were prospectively included, with a total number of 42 lymph nodes examined by EUS elastography. By using a qualitative pattern analysis, we were able to differentiate between benign and malignant lymph nodes with a high sensitivity, specificity and accuracy (91.7 %, 94.4 % and 92.86 %, respectively), based on five pre-defined patterns obtained on EUS elastography. A quantitative analysis based on histograms of the EUS elastography images also allowed an excellent discrimination between benign and malignant lymph nodes. Based on separate RGB channel histogram values, an "elasticity ratio" was further defined and yielded a sensitivity, specificity and accuracy for the differential diagnosis of 95.8 %, 94.4 % and 95.2 % respectively, based on a cut-off level of 0.84. CONCLUSION: EUS elastography is a promising method which allows characterisation and differentiation of benign and malignant lymph nodes with a high sensitivity, specificity and accuracy, offering complementary information added to conventional EUS imaging.

Adult↗
PubMed2005

Utility of colour Doppler endoscopic ultrasound evaluation and guided therapy of submucosal tumours of the upper gastrointestinal tract.

BACKGROUND AND AIMS: Endoscopic ultrasound is considered the method of choice for evaluation of submucosal tumours. Endoscopic therapy of selected lesions represents a useful mini-invasive approach. The aim of this study was to assess the endoscopic management of submucosal tumours of the upper gastrointestinal tract (GIST), with emphasis on the use of colour and power Doppler endoscopic ultrasound. METHODS: The study included 35 consecutive patients referred to endoscopic ultrasound with submucosal tumours of the upper gastrointestinal tract. Colour and power Doppler imaging were performed with radial or linear instruments in all patients and allowed a better characterisation of the submucosal lesions. Histology was obtained in 22 patients and permitted a correct diagnosis, as well as confirmation or exclusion of malignancy. RESULTS: In 18 patients (51.4%) there was discrepancy between the suspected endoscopic diagnosis and the diagnosis made by endoscopic ultrasound. Most of the malignant GISTs had significant intratumoural vessels detected by colour or power Doppler EUS (5 out of 6 patients, 83.3%), as compared with the benign GISTs (2 out of 7 patients, 28.6%). Colour Doppler EUS was essential, both to diagnose and to direct therapy in vascular submucosal lesions (two haemangiomas). The same technique was useful to better characterise lipomas or cysts. CONCLUSIONS: Endoscopic ultrasound management of submucosal tumours was enhanced by the use of colour and power Doppler imaging. A precise management plan, supported by colour and power Doppler findings improved the diagnostic options and increased the feasibility and safety of endoscopic ultrasound guided therapeutic interventions.

Duodenal Neoplasms↗
PubMed2005

Genomic species identification of Acinetobacter of clinical isolates by 16S rDNA sequencing.

INTRODUCTION: This study aims to identify Acinetobacter of clinical isolates from the University of Malaya Medical Centre (UMMC), Kuala Lumpur, to the species level by 16S rDNA sequencing. METHODS: 12 representative Acinetobacter isolates of the UMMC inpatients were randomly picked and used for the study. The 16S rDNA sequences were determined and phylogenetic relationships to all known Acinetobacter species were established. RESULTS: Based on the 16S rDNA sequences, all the UMMC isolates were identified as Acinetobacter baumannii. The isolates shared a common ancestral lineage with the prototypes Acinetobacter baumannii DSM30007 and DSM30008 with 99-100 percent sequence similarities. The isolates could be differentiated into two groups by a single nucleotide difference (thymine-cytosine) within the 16S rRNA sequence. Three different genotypes, 1, 3 and 4, were recognised using REP-PCR. CONCLUSION: The previously uncharacterised Acinetobacter isolates from the UMMC were identified by their 16S rDNA sequences as Acinetobacter baumannii. The isolates were distinguished into at least three different genotypes by REP-PCR genotyping. These findings confirmed for the first time the presence of Acinetobacter baumannii of different genotypes among patients at UMMC.

Acinetobacter baumannii↗
PubMed2005

Focal non-typhoidal Salmonella infections from a single center in Malaysia.

A retrospective review of patients with focal non-typhoidal Salmonella (NTS) infection was performed to determine its features and outcome. All patients with focal NTS infection admitted to the University of Malaya Medical Center, Malaysia, from 1993 to 2002 were studied. More than half (58%) of the 35 cases (54% male, median age 39 years, range 1.5 months to 79 years) were immunocompromized or had chronic medical conditions. One-third of the patients (34%) had superficial infections (lymphadenitis or subcutaneous tissue infection) and all recovered with antimicrobial therapy alone. Deep infections (66%) noted were: meningitis (9%), osteomyelitis or arthritis (26%), abscesses of the gastrointestinal tract or adjacent organs (20%), and others (11%). Deep infections were more likely to occur in the extremes of age (<6 months or >60 years, p< 0.04), associated with adverse outcomes with an overall mortality rate of 9%, or required major surgery (15%).

Adolescent↗
PubMed2004

Antibiotic susceptibility and REP-PCR fingerprints of Acinetobacter spp. isolated from a hospital ten years apart.

The antibiotic susceptibility profiles and the repetitive extragenic palindromic sequence-based polymerase chain reaction (REP-PCR)-determined genotypes of 109 Acinetobacter strains collected from the University Malaya Medical Center (UMMC), Kuala Lumpur, Malaysia, in 1987 (N=21) and 1996-1998 (N=88) were established. Twelve antibiotic susceptibility profiles of antibiotics used at the UMMC were obtained. In descending order of effectiveness, imipenem, amikacin and ciprofloxacin were the most effective against the Acinetobacter strains. Compared with 1987 isolates, the isolates obtained in 1996-1998 had decreased susceptibility to these antibiotics and were tolerant to the antibiotics up to an MIC90 of > or =256 mg/L. REP-PCR DNA fingerprints of all the isolates revealed the presence of four Acinetobacter spp. lineages; 92% of all the isolates belonged to two dominant lineages (genotypes 1 and 4). Genotype 4 isolates predominant in 1987 showed increased resistance and antibiotic tolerance to imipenem, amikacin and ciprofloxacin compared with the 1996-1998 isolates. In contrast, genotype 1 isolates from 1996-1998 were mainly sensitive to these antibiotics. These findings demonstrate the presence of at least two independent Acinetobacter spp. lineages in the same hospital, and suggest the possibility that genotype 4 Acinetobacter spp. acquired the resistance phenotype in situ, whereas most of the genotype 1 isolates were probably introduced to the hospital in recent years.

Acinetobacter↗
PubMed2004

Insufficient cholecystectomy diagnosed by endoscopic ultrasonography.

Recurrent attacks of upper right quadrant pain after cholecystectomy are not infrequent. In most of these cases, the cause of the pain remains undiagnosed. Insufficient cholecystectomy has been described as a rare cause of post-cholecystectomy pain, although the true incidence is unknown. It is difficult to diagnose a residual gallbladder or a large cystic duct with residual stones, due to the size of the remaining structures. This report presents three patients who had experienced a long period of agonizing biliary-type pain after cholecystectomy. Abdominal ultrasound examinations, and magnetic resonance cholangiopancreatography (MRCP) in one patient, were normal. Endoscopic ultrasonography (EUS) demonstrated the presence of a small cystic structure with echogenic foci compatible with a residual gallbladder containing small gallstones. Two of the three diagnoses were confirmed by repeat surgery. EUS thus appears to be a valuable method for diagnosing insufficient cholecystectomy, and should be considered in patients with persistent pain attacks after cholecystectomy.

Cholecystectomy↗
PubMed2004

Endoscopic ultrasonography in detection of cholelithiasis in patients with biliary pain and negative transabdominal ultrasonography.

BACKGROUND: The aim of the study was to evaluate endoscopic ultrasonography (EUS) as a single method for diagnosing cholecystolithiasis in patients with a clinical suspicion of cholecystolithiasis, but with a normal transabdominal ultrasonography (TUS). METHODS: A prospective study was performed on patients with biliary type of colic and normal US of the gallbladder. All patients had at least one normal TUS examination (mean 2.1, range 1-5) performed by an experienced radiologist. All patients were subsequently examined with EUS. EUS examination was performed with either a mechanical radial scanning echo-endoscope (Olympus GF-UM20) or a linear echo-endoscope (Pentax FG32-UA or FG34-UA). Patients in whom EUS demonstrated cholecystolithiasis were offered laparoscopic cholecystectomy within 2 weeks. RESULTS: A total of 35 patients (31 F and 4 M) were included. In 18 out of 35 (52.4%) patients cholecystolithiasis was diagnosed by EUS. In 15 out of 17 patients the EUS diagnosis was verified by surgery. At follow-up after 12 months, 13 of the 15 patients (87%) with verified gallbladder stones had no abdominal discomfort, whereas 2 patients (13%) complained of persistent and unchanged abdominal pain. CONCLUSION: EUS seems to be a promising imaging method in the detection of microlithiasis in the gallbladder in patients with clear biliary colic and normal transabdominal US.

Abdomen↗
PubMed2004

Forecasting daily maximum surface ozone concentrations in Brunei Darussalam--an ARIMA modeling approach.

A time series approach using autoregressive integrated moving average (ARIMA) modeling has been used in this study to obtain maximum daily surface ozone (O3) concentration forecasts. The order of the fitted ARIMA model is found to be (1,0,1) for the surface O3 data collected at the airport in Brunei Darussalam during the period July 1998-March 1999. The model forecasts of one-day-ahead maximum O3 concentrations have been found to be reasonably close to the observed concentrations. The model performance has been evaluated on the basis of certain commonly used statistical measures. The overall model performance is found to be quite satisfactory as indicated by the values of Fractional Bias, Normalized Mean Square Error, and Mean Absolute Percentage Error as 0.025, 0.02, and 13.14% respectively.

Air Pollutants↗
PubMed2004

Pioglitazone reduces blood pressure in non-dipping diabetic patients.

AIM: The association between insulin resistance and hypertension is firmly established and has been extensively investigated. Thiazolidinediones (TZD), a class of oral hypoglycemic agents that act as insulin sensitizers have been demonstrated, in many in vivo and in vitro studies, to possess antihypertensive properties. Whether the ability of TZD to lower blood pressure (BP) should be ascribed to a reduction of insulin resistance, or to a direct vasodilating effect, is matter of debate. Since blunted BP nocturnal dipping precedes overt hypertension and is associated with an increased risk of adverse cardiovascular events, we evaluated the pioglitazone effects on BP in non-dipper type 2 diabetic patients. METHODS: Forty non-dipper diabetic patients were randomly assigned to metformin + placebo (M) or metformin + pioglitazone 30 mg (MP) and submitted to 24 hours blood pressure monitoring at the beginning and after 8 weeks. RESULTS: After 8 weeks of treatment in subjects on metformin + pioglitazone 30 mg (group MP1), we found a reduction of nocturnal blood pressure values (mean nocturnal systolic BP 128.05+/- 1.23 vs 122.8+/-2.3 mmHg; p<0.02; mean nocturnal diastolic BP 81.2+/-0.99 vs 75.65+/-0.93 mmHg; p<0.005). The observed improvements in BP were independent from changes in metabolic parameters. CONCLUSION: The obtained data show that pioglitazone was effective in reducing BP values in non-dipping diabetic patients. The reduction of BP values was independent from amelioration of the metabolic picture: that suggest the hypothesis that these ameliorations may be also due to a direct antihypertensive action exerted by pioglitazone.

Antihypertensive Agents↗
PubMed2001

Distinct orders of GalNAc incorporation into a peptide with consecutive threonines.

Mucin O-glycosylation is initiated by a transfer of N-acetyl-d-galactosamine (GalNAc) to Ser and Thr residues in polypeptides with a family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (pp-GalNAc-Ts). In this paper, four human pp-GalNAc-Ts (pp-GalNAc-T1, T2, T3, and T4) were tested for their preferential orders of GalNAc incorporation into FITC-PTTTPITTTTK, a portion of the tandem repeat of human MUC2. The products were separated by reverse-phase HPLC and characterized by MALDI-TOF MS and peptide sequencing. pp-GalNAc-T1 showed preference for acceptor sites, but the order of the incorporation into these sites seemed to be random. In contrast, the GalNAc incorporation by pp-GalNAc-T2, T3, or T4 was not only site-specific but also according to the specific orders. Furthermore, pp-GalNAc-T2, T3, or T4 had distinct maximum numbers of GalNAc incorporations into this peptide.

Acetylgalactosamine↗
PubMed2001

Mass spectrometric determination of O-glycosylation sites using beta-elimination and partial acid hydrolysis.

The present study demonstrates that treating O-glycosylated peptides with methylamine vapor followed by partial acid hydrolysis is an effective means for locating O-glycosylation site(s). The reaction with methylamine transforms the glycosylated Ser and Thr residues into stable methylamine derivatives with a mass increment of +13 Da relative to nonglycosylated Ser and Thr residues. Peptide sequencing based on partial acid hydrolysis followed by mass spectrometric analysis or in favorable cases by CID-MS/MS enables the determination of the formerly O-glycosylated sites.

Acids↗
PubMed2001

Papillary fibroelastoma of a mitral valve chorda.

A 43-year-old woman presented with an ischemic stroke in the right middle cerebral artery territory. Cardiac echography disclosed a tumor of a primary chordae of the anterior leaflet of the mitral valve. After neurologic recovery, the patient was referred to surgery for excision of the tumor and plastic reconstruction using a chordal transfer technique. Histological examination of the tumor showed a typical papillary fibroelastoma. Papillary fibroelastoma is the third most frequent cardiac benign tumor. The high embolic potential of this tumor is in favor of an aggressive surgical attitude.

Adult↗
PubMed2001

N-acetylgalactosamine incorporation into a peptide containing consecutive threonine residues by UDP-N-acetyl-D-galactosaminide:polypeptide N-acetylgalactosaminyltransferases.

A limited number of glycosylation products were generated in a cell-free system from a portion of the MUC2 tandem repeat, PTTTPITTTTK, when microsome fractions of human colon carcinoma LS174T cells were used as the source of UDP-N-acetyl-D-galactosaminide:polypeptide N-acetylgalactosaminyltransferases (pp-GalNAc-T) in our previous work. The structures of all products suggested that there were only two biosynthetic pathways in the GalNAc incorporation into this peptide. In the present report, the putative biosynthetic intermediates, PTTT*PITTTTK (asterisk designates a GalNAc residue), PT*TTPITTTTK, PTT*T*PITT*T*TK, and PT*TTPIT*T*T*TK, of these two hypothetical pathways were used as acceptors to prove that these two pathways do exist. The incubation products of these glycopeptides, microsome fractions of LS174T cells, and UDP-GalNAc were fractionated by reverse-phase HPLC and their structures were determined using MALDI-TOF MS and peptide sequencing. The products from PTTT*PITTTTK were PTTT*PITTT*TK, PTTT*PITT*T*TK, PTT*T*PI-TT*T*TK, PTT*T*PIT*T*T*TK, PT*T*T*PIT*T*T*TK, and PT*T*T*PIT*T*T*T*K. The products from PTT*-T*PITT*T*TK exactly corresponded to the products with five to seven GalNAc residues from PTTT*PITTTTK. The products from PT*TTPITTTTK were PT*TTPITT*TTK, PT*TTPIT*T*TTK, and PT*TTPIT*T*T*TK. PT*TTP-IT*T*T*TK was not converted further under the applied condition. All the products detected and analyzed were the same as those obtained when the unsubstituted peptide and microsome fractions of LS174T cells were incubated. Immunocytochemical analysis indicated that LS174T cells contain at least four pp-GalNAc-Ts (-T1, -T2, -T3, and -T4), suggesting that control of the order and the maximum number of GalNAc incorporation into this peptide is regulated through the coordinated actions of these and possibly other pp-GalNAc-Ts.

Acetylgalactosamine↗
PubMed2000

The lectin domain of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-T4 directs its glycopeptide specificities.

The initiation step of mucin-type O-glycosylation is controlled by a large family of homologous UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases). Differences in kinetic properties, substrate specificities, and expression patterns of these isoenzymes provide for differential regulation of O-glycan attachment sites and density. Recently, it has emerged that some GalNAc-transferase isoforms in vitro selectively function with partially GalNAc O-glycosylated acceptor peptides rather than with the corresponding unglycosylated peptides. O-Glycan attachment to selected sites, most notably two sites in the MUC1 tandem repeat, is entirely dependent on the glycosylation-dependent function of GalNAc-T4. Here we present data that a putative lectin domain found in the C terminus of GalNAc-T4 functions as a GalNAc lectin and confers its glycopeptide specificity. A single amino acid substitution in the lectin domain of a secreted form of GalNAc-T4 selectively blocked GalNAc-glycopeptide activity, while the general activity to peptides exerted by this enzyme was unaffected. Furthermore, the GalNAc-glycopeptide activity of wild-type secreted GalNAc-T4 was selectively inhibited by free GalNAc, while the activity with peptides was unaffected.

Amino Acid Sequence↗
PubMed2000

Central neurocytoma: 2 case reports and review of the literature.

Central neurocytoma is a rare benign tumor of the central nervous system occuring in young adults and typically located in the ventricles. The tumor is composed of small round cells with neuronal differentiation and has a favourable prognosis. We report two cases of giant central neurocytomas with a triventricular extension in two young women. The first case concerned a 26 years old righthanded woman in whom an intraventricular mass was discovered, after a car accident with head trauma. Skull radiography showed an enlargment of the sella turcica. A CT scan performed in order to examine the pituitary gland revealed a voluminous and heterogenous intraventricular tumor with calcification. The second case concerned a 26 years old righthanded woman, presenting with a 4 Glasgow Coma Scale Score preceded by an acute onset of headache with projectile vomiting. A CT scan performed in emergency revealed a voluminous intraventricular mass with significant hydrocephalus. We review the different pathological and topographical patterns of previously published neurocytomas and discuss surgical management, effectiveness of radiation therapy and biological behavior.

Adult↗
PubMed2000

Successful treatment of normeperidine neurotoxicity by hemodialysis.

Normeperidine, a major metabolite of meperidine, is half as potent as meperidine as an analgesic but two to three times more potent as a convulsant. Renal failure significantly increases the plasma half-life of normeperidine. The intensity of the central nervous system excitation is highly correlated with the plasma concentration of normeperidine. Moreover, normeperidine toxicity is not reversed by naloxone, which may exacerbate it. We report a patient with end-stage renal disease undergoing maintenance continuous cycler peritoneal dialysis who had been receiving meperidine for pain control. The patient subsequently developed myoclonic contractions and a grand mal seizure. The patient was successfully treated with hemodialysis (using an F8 dialyzer) for presumed normeperidine-induced seizure. During hemodialysis, normeperidine average blood clearance was 73 mL/min, average plasma clearance was 50 mL/min, and average percentage of plasma extraction was 24%. There also was a 26% reduction in plasma concentration of normeperidine over 3 hours of hemodialysis. In conclusion, our findings suggest that hemodialysis may be used effectively for treating patients with suspected normeperidine-induced neurotoxicity.

Aged↗