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Biomedical subjects

F Hassan

Publications and source records attributed to F Hassan.

At least 19 recordsLinked to original sources

Altering trends in the dominance of Shigella flexneri serotypes and emergence of serologically atypical S. flexneri strains in Dhaka, Bangladesh.

Of 469 recently isolated Shigella flexneri strains, 452 agglutinated with Shigella flexneri-specific monoclonal antibodies. Of these, 396 could be assigned to 10 of the currently recognized 15 serotypes, with S. flexneri 2b dominating (23.2%). Of the 56 untypeable strains which showed invasive properties, 17 were serologically atypical and the remaining 39 belonged to a new serotype.

Bacterial Typing Techniques↗

The cross cultural context of obesity: an INCLEN multicentre collaborative study.

Associations between obesity and cardiovascular disease have been documented in the Developed World and have been linked with levels of 'development' in Developing World countries. This study aimed to explore the sociocultural influences on attitudes towards obesity, physical activity and dietary change using a four level conceptual framework (from personal to societal influences). Focus group discussions were conducted in: India, Indonesia, Cameroon, Egypt and Australia. The results of these discussions were analysed to reveal emergent themes. The interpretation of the qualitative data emphasised the need to incorporate influences beyond the individual in efforts to reverse or prevent obesity related disease.

Adult↗

Prevalence of hepatitis G virus in Pakistani children with transfusion dependent beta- thalassemia major.

We ought to obtain data on the prevalence of the newly discovered tranfusion transmittable hepatitis G virus in polytransfused b- thalassemia major children. Each individual had received multiple blood transfusions, from 12 to 36 per year. No documentation of prior hepatic infection was available. Serum samples were collected prospectively from the randomly selected subjects and were analyzed for HGV RNA by polymerase chain reaction using primer specific for two different regions of the HGV genome. Among the 100 individuals examined 21 were positive for HGV RNA. Four patients had evidence of dual infection, both HGV RNA and HCV RNA were isolated from their sera. While in one sample presence of both HGV RNA and HBV DNA was established. Only one child was positive for hepatitis E antibodies. The sera of 10 children were reactive for hepatitis B surface antigen whereas 35 individuals were positive for hepatitis C virus antibody. The ALT levels were variable in HGV infected children. Four out of 16 (25%) showed peak ALT levels of 218 IU/I, 8/16 (50%) children demonstrated slightly elevated ALT levels whereas 25% individuals showed normal ALT levels. Alkaline Phosphatase levels were elevated in 90% of the children and 20% patients of this series also had higher GGT levels. The observed AP levels were not statistically different among HGV, HGV/HCV or HGV/HBV groups. Even though the ALT levels were deranged in the children with HGV alone but none of the children had demonstrated symptoms of liver disease, their direct and total bilirubin levels were normal and no complain of jaundice was recorded. In conclusion, our findings suggested that like other blood borne hepatic viruses, HGV is also prevalent in the high risk group of multiple transfused patients in Pakistan but our results support the absence of any causal relationship between HGV and hepatitis.

Blood Transfusion↗

A novel Glu421Lys substitution in the lipoprotein lipase gene in pregnancy-induced hypertriglyceridemic pancreatitis.

Severe hypertriglyceridemia is an uncommon pathological finding in pregnant women if there is no prior history of hyperlipidemia. A partial reduction in lipoprotein lipase (LPL) activity due to a mutation in the LPL gene, is often an associating factor. Here we report a novel LPL gene mutation (Glu421Lys), in a previously healthy primigravid woman who died from hypertriglyceridemia-induced pancreatitis during the last trimester of pregnancy. The patient was heterozygous for this mutation which a charge inversion in the C-terminal domain of LPL resulting in a moderate reduction in catalytic activity, both in vivo and in vitro. These data support the role of partial LPL deficiency in the pathogenesis of severe gestational hypertriglyceridemia.

Adult↗

Effects of pulsed high-frequency electromagnetic fields on the neuroendocrine system.

The influence of pulsed high-frequency electromagnetic fields emitted from a circularly polarized antenna on the neuroendocrine system in healthy humans was investigated (900 MHz electromagnetic field, pulsed with 217 Hz, average power density 0.02 mW/cm2). Nocturnal hormone profiles of growth hormone (GH), cortisol, luteinizing hormone (LH) and melatonin were determined under polysomnographic control. An alteration in the hypothalamo-pituitary-adrenal axis activity was found with a slight, transient elevation in the cortisol serum level immediately after onset of field exposure which persisted for 1 h. For GH, LH and melatonin, no significant effects were found under exposure to the field compared to the placebo condition, regarding both total hormone production during the entire night and dynamic characteristics of the secretion pattern. Also the evaluation of the sleep EEG data revealed no significant alterations under field exposure, although there was a trend to an REM suppressive effect. The results indicate that weak high-frequency electromagnetic fields have no effects on nocturnal hormone secretion except for a slight elevation in cortisol production which is transient, pointing to an adaptation of the organism to the stimulus.

Adolescent↗

A new mutation destroying disulphide bridging in the C-terminal domain of lipoprotein lipase.

Lipoprotein lipase (LPL) is one of two intravascular lipases involved in the lipolysis of the triglyceride core of circulating lipoproteins. The occurrence of patients with genetic deficiencies has provided insight into the structure and function relationships of this lipase. It is now known that LPL manifests a two domain structure with the N-terminal domain of greater structural and functional significance as it contains the active site and interfacial binding motifs. We report on a Cys418Tyr substitution in the C-terminal domain which disrupts the only disulphide bridge in the region and is associated with catalytic deficiency in post-heparin plasma. This result was unexpected as previous in vitro assessment of the functional significance of disulphide bridging had shown that while the 3, N-terminal disulphides were critical for enzyme function, loss of the only C-terminal disulphide minimally affected catalytic activity. We generated the Cys418Tyr mutant by site-directed mutagenesis and show that it manifests 48% of normal activity in vitro, while the companion variants, Cys438Ser and Cys418Ser-Cys438Ser, are less affected with activities at 76% and 78% of normal.

Adult↗

Helicobacter pylori infection and dental care.

Sixty two patients (mean age 45.6 years) were assessed for oral hygiene and periodontal disease by dental examination before endoscopy. Information about oral care, smoking, and dentures was obtained and samples of dental plaque collected. The presence of Helicobacter pylori in plaque as sought by culture and polymerase chain reaction (PCR), and gastric antral biopsy specimens were taken for histological examination. Although H pylori was detected in the antral specimens of 34 patients (54%) all of the cultures of dental plaque were negative, and PCR was only positive from the dentures of one patient. Smokers had poor oral hygiene, visited their dentist less often, and brushed their teeth less frequently. There was no correlation of H pylori gastritis with either dental hygiene or periodontal disease. These results suggest that dental plaque or dentures are not an important reservoir for H pylori and are probably not a significant factor in transmission of the organism. The conflicting results in published works may be caused by differences in sample collection, culture techniques, or oral contamination from gastric juice as a result of gastro-oesophageal reflux at the time of endoscopy.

Adult↗

Penetration of mitomycin C in human bladder.

The penetration of mitomycin C (MMC) in bladder tissue was studied in patients who received intravesical chemotherapy at the time of radical cystectomy. An intravesical dose of MMC (20 mg/40 ml) was instilled and maintained in the bladder for 60 to 120 min at which time the solution was drained. Within 10 to 60 min after draining the drug solution, the bladder vasculature was ligated, and the bladder was removed. Tissues were sectioned serially in layers parallel to the urothelium and analyzed for MMC concentration. Of the 24 patients evaluated, 17 patients had a low final MMC concentration in urine (< 66 micrograms/ml) or had the MMC solution drained more than 30 min before ligation of the blood vessels. Among these 17 patients, the concentration in the urothelium was measurable in only 4 patients, while the concentrations in deeper tissues were not measurable. In the remaining 7 patients where the urine concentration was > 120 micrograms/ml and where the vasculature was ligated within 30 min after the MMC solution was drained, the bladder wall contained significant MMC concentrations. The drug penetration was studied in the latter 7 patients, using sections of bladder wall that were grossly normal and non-tumor bearing. Concentrations in the bladder wall declined semilogarithmically with tissue depth from the urothelium to the deep muscle and reached a plateau at about 2000 microns depth. The median MMC concentrations were 5.6 micrograms/g in the urothelium and lamina propria interface, 2.7 micrograms/g in the lamina propria, and 0.9 microgram/g in the muscularis. The distance over which the MMC concentration decreased by one-half was about 500 microns. The concentration ratio between the urine and urothelium/lamina propria interface was about 35-fold. The mean plasma concentrations were 0.003, 0.1, and 0.4% of the mean concentration in urine, urothelium, and the averaged bladder tissue concentrations, respectively. Paired superficial tumor and normal tissues were obtained from 5 bladders. In 4 of 5 cases, the concentration in tumors was higher than in normal tissues, while the reverse was seen in the remaining tumor. In one sessile bladder tumor a complete concentration-depth profile could be obtained. While the concentrations in the tumor tissue were 2-3-fold higher than that in the adjacent normal tissue, the rate of concentration declined with respect to tissue depth and hence the distance over which the MMC concentration decreased by one-half was similar in both tumors.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Intravesical↗

The lipoprotein lipase Gly188----Glu mutation in South Africans of Indian descent: evidence suggesting common origins and an increased frequency.

Lipoprotein lipase (LPL) plays a crucial role in the hydrolysis of the triglyceride core of circulating chylomicrons and very low density lipoproteins (VLDL) and also has a major effect on the levels and lipid composition of high density lipoproteins (HDL). LPL deficiency is inherited as an autosomal recessive trait and most commonly presents with chylomicronaemia, abdominal pain, and eruptive xanthomata. We have previously described a mutation in exon 5 of the LPL gene which results in a substitution of glutamic acid for glycine at amino acid 188. We have now assessed 16 South African LPL deficient patients from nine separate kindreds for this mutation. Nine of these probands were homozygous for the mutation and were from four families, all of Indian descent. The ancestors of these probands have their origins in villages close to Bombay, India, which suggests a common ancestral mutation for the four Indian kindreds, particularly as the mutant allele in each family carried the identical restriction fragment length polymorphism (RFLP) haplotype. The presence of at least nine affected subjects in this small community around Cape Town is evidence for a higher than expected gene frequency for LPL deficiency in this population.

Base Sequence↗

Purification and characterization of pyocins R from Pseudomonas aeruginosa.

Five types of pyocins were found in Pseudomonas aeruginosa strain 112. Production of these types was induced by UV irradiation. The pyocin activity was found to be resistant to trypsin treatment. Their molar mass was found to be 282, 251, 112, 89.1 and 54.9 kg/mol, respectively. The pyocins obtained were different from any known type (such as R, S, F) in their chemical and physical properties.

Bacteriocins↗

Purification and characterization of pyocins from Pseudomonas aeruginosa.

Three types of pyocins were found in Pseudomonas aeruginosa strain 986 and named pyocin type P25, P50, and P70. Production of these types was inducible by UV irradiation. Their molar mass was estimated. The pyocins obtained were different from the known pyocins R, S, and F in their chemical and physical properties. No immunological cross reaction was observed among these pyocins.

Amino Acids↗

An evaluation of quantitative techniques for Schistosoma haematobium eggs in urine preserved with carbolfuchsin.

The objective of this study was to determine a suitable method for quantitating Schistosoma haematobium eggs in urine specimens preserved in carbolfuchsin. Using a 0.002% carbolfuchsin-phenol-alcohol solution as a stain/preservative for urine obtained from 30 patients infected with S. haematobium, we compared egg counts obtained with four quantitative techniques: Nytrel filtration, Nuclepore filtration, suction filtration and centrifugation. Centrifugation gave statistically higher values than all other techniques for absolute number of eggs recovered in the preserved urine. We also measure a statistical difference between the counts obtained from Nuclepore filtration of fresh urine and those established on an equivalent volume of preserved urine by Nuclepore and Nytrel filtration. The preserved urine frequently caused obstruction of both Nuclepore filters and Whatman No. 1 filters (used in suction filtration), rendering them technically difficult to use and less satisfactory than other methods. From the techniques we examined, we conclude that in field studies where preservation of urine is necessary, preparation of Nuclepore filters with fresh urine, or centrifugation of a carbolfuchsin-preserved urine, are the methods of choice for quantitation of specimens.

Animals↗

Acid and alkaline phosphomonoesterases in Egyptian snake venoms.

Non-specific acid and alkaline phosphomonoesterases could be demonstrated in two viperids (Cerastes cerastes and Cerastes vipers) and two elapids (Naja haje and Naja nigricollis). The latter could be a natural source for the production of these enzymes. The activities of both enzymes in elapids were greater than in viperids. N. nigricollis was the only to show acid phosphatase activity exceeding its alkaline one. The optimum pH values recorded for acid phosphatase was 4.0 and 4.9 and for alkaline phosphatase 9.0 and 10.0 in viperids and elapids, respectively. Optimum substrate concentration for both enzymes in viperids was 0.01 M, while for acid phosphatase in N. haje and N. nigricollis it was 0.125 and 0.150 M; and for their alkaline phosphatases the values were 0.150 and 0.125 M, respectively. Mg++ behaved as an activator for both enzymes in all venoms investigated, while Zn++ showed either no or slight activating effect. Fluoride ions as well as EDTA showed certain inhibitory action. Both enzymes in the crude venoms were heat-labile.

Acid Phosphatase↗

Congo/Crimean haemorrhagic fever in Iraq.

Congo/Crimean haemorrhagic fever was recognized for the first time in Iraq in 1979. The first case was reported on 3 September 1979 and since then a further 9 patients have been investigated. Eight patients gave a history of previous contact with sheep or cattle, while 2 patients, a resident doctor and an auxiliary nurse, acquired their infections in hospital by direct contact with patients. The causal virus was isolated from patients' blood and postmortem liver specimens. The virus isolates were found to be closely related if not identical serologically to members of the Congo/Crimean haemorrhagic fever virus group. Eight of the patients had no epidemiological relationship to one another and lived in widely separated areas around Baghdad and Ramadi (110 km to the west of Baghdad).

Adolescent↗

Biochemical properties of Egyptian Cerastes venoms in relation to geographic distribution.

Total proteins, electrophoretic analysis, biological lethality, and phospholipase activity of five members of the Cerastes-viper species living along the Nile Valley were investigated. Elevation of environmental temperature was accompanied with high values for these indices. It is concluded that zoological distribution and environmental conditions could influence the overall biological behaviour of snake venoms of the same species.

Animals↗