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Biomedical subjects

M Ibrahim

Publications and source records attributed to M Ibrahim.

At least 55 records · Page 3Linked to original sources
PubMed1999

Capillaria philippinensis: an emerging parasite causing severe diarrhoea in Egypt.

Four cases with Capillaria philippinensis have been reported from Egypt during 1989-1992. The authors report here four other cases of severe diarrhoea caused by this parasite. A male and three female patients aged 12-45 years presented with severe diarrhoea of 1-7 months duration associated with vomiting and central abdominal colics. Stools were yellowish or greenish and voluminous. Anorexia was profound with loss of weight. Bilateral painless ankle oedema developed early in the course of the disease and two cases had ascites and bilateral pleural effusion at presentation. There was hyponatraemia, hypocalcaemia and marked hypokalaemia and hypoalbulinaemia. Small bowel series showed a rapid transit time in 3 cases and malabsorption pattern in one. Duodenal biopsies showed non-specific chronic inflammation while jejunal biopsies from one case revealed grade II villous atrophy with moderate cellular infiltration of lamina propria. The infection was diagnosed by finding the eggs, larvae and adult worms of C. philippinensis in stool. Patients were treated with mebendazole 400 mg/day in two divided doses for 28 days in addition to high protein diet and correction of electrolyte disturbance. Vomiting stopped on the second day of treatment, appetite improved and diarrhoea regressed by the fourth day. Unfortunately, one case died two days after admission due to marked hypokalaemia. Clinico-pathological and epidemiological aspects of this infection in Egypt are discussed.

Adult↗
PubMed1998

On the expression of cytosolic calcium-independent phospholipase A2 (88kDa) in immature and mature myeloid cells and its role in leukotriene synthesis in human granulocytes.

The human calcium-independent phospholipase A2 (iPLA2; 88 kDa) has recently been cloned (Larsson, P.K.A., Claesson, H.-E. and Kennedy, B.P. (1998) J. Biol. Chem. 272, 207-214). Here we demonstrate the expression of the human iPLA2 mRNA and its splice variants in blood progenitor cells, immature leukemic cells and mature granulocytes. Chromatographical resolvable iPLA2 activity was found in the cytosolic fraction of granulocytes and the activity was inhibited by the iPLA2 inhibitor bromoenol lactone. This drug also inhibited leukotriene synthesis in human granulocytes, induced by low concentration of calcium ionophore A23187 (0.10-0.15 microM) or opsonized zymosan. These results suggest that iPLA2 is involved in the regulation of the pool of arachidonic acid destined for leukotriene synthesis in human granulocytes.

Adult↗
PubMed1998

Differential expression of the L- and S-isoforms of myelin associated glycoprotein (MAG) in oligodendrocyte unit phenotypes in the adult rat anterior medullary velum.

We have previously demonstrated differences in the expression of carbonic anhydrase II (CAII) in oligodendrocyte units myelinating small and large diameter fibres in the anterior medullary velum (AMV) of the adult rat (each unit comprises the cell body, processes and myelin sheaths). Others have indicated that myelin composition may also vary with respect to myelin basic protein (MBP) and proteolipid protein (PLP), and the small (S)- and large (L)-isoforms of myelin associated glycoprotein (MAG). In this study, we have determined the expression of myelin proteins in oligodendrocyte unit phenotypes I-IV, which myelinate fibres ranging in diameter from 0.3-12 microns diameter in the AMV, by using double immunolabelling for Rip, which labels entire units, and MBP, PLP, myelin oligodendrocyte glycoprotein (MOG), L-MAG and S-MAG. We show differences in the expression of L- and S-MAG in units which myelinate different diameter fibres: (1) type I/II units myelinating small diameter fibres had a L-MAG+/S-MAG-/CAII+ phenotype; (2) type II/III units myelinating different diameter fibres had a L-MAG+/S-MAG+/CAII+ phenotype; (3) type III/IV units myelinated large diameter fibres had a L-MAG+/S-MAG+/CAII- phenotype. All units, irrespective of fibre diameter, expressed Rip, MBP, PLP and MOG. The results indicate that type I-IV units may be variants of a single oligodendrocyte population and that phenotypic differences are determined by the diameter of fibres within the unit. The possible significance of metabolic and biochemical differences between oligodendrocytes myelinating small and large diameter axons are discussed with reference to the pathology of demyelination.

Age Factors↗
PubMed1998

Effect of triclosan on interleukin-1 beta production in human gingival fibroblasts challenged with tumor necrosis factor alpha.

The effect of the dentifrice ingredient triclosan (2,4,4'-trichloro-2'-hydroxyldiphenyl ether) on the production of interleukin (IL)-1beta and IL-6 was studied in human gingival fibroblasts challenged with tumor necrosis factor alpha (TNFalpha) in vitro. When gingival fibroblasts were treated simultaneously with triclosan (0.25, 0.5 microg/ml) and TNFalpha (10 ng/ml), the stimulatory effect of TNFalpha on IL-1beta production was reduced by the agent. In situ hybridisation showed that the TNFalpha-induced expression of IL-1beta mRNA was significantly reduced by triclosan. Furthermore, when the cells were treated simultaneously with a known protein kinase C (PKC) activator, phorbol 12-myristate-13-acetate (PMA) and TNFalpha in the presence of triclosan (0.5 microg/ml), the agent reduced the production of IL-1beta. In contrast to its effect on IL-1beta, triclosan did not influence the mRNA expression or the production of IL-6 induced by TNFalpha. The finding that triclosan reduces the production of the inflammatory mediator IL-1beta in gingival fibroblasts further supports the view that triclosan exhibits an anti-inflammatory effect.

Anti-Infective Agents, Local↗
PubMed1998

One year of experience working with the aid of a robotic assistant (the voice-controlled optic holder AESOP) in gynaecological endoscopic surgery.

The aim of the study was a comparison of robotic versus human laparoscopic camera control. Utilizing robotic technology a robot has been designed specifically for the purpose of holding and manoeuvring the laparoscope under the direct control of the surgeon. We tested AESOP (automated endoscopic system for optimal positioning) in 50 patients undergoing routine gynaecological endoscopic surgical procedures. The elimination of the camera holder allows two doctors to perform complex laparoscopic surgery faster than without the robotic arm. The timing of surgical procedures performed by surgeons using the voice control was compared to the timing of similar operations using the foot or hand control. The voice-controlled AESOP works more efficiently and faster than the hand or foot control.

Endoscopes↗
PubMed1998

Axon-myelin sheath relations of oligodendrocyte unit phenotypes in the adult rat anterior medullary velum.

Axon-oligodendrocyte relations of Rip-immunolabelled and dye-injected oligodendrocyte units are characterised in the adult rat anterior medullary velum (AMV). Each oligodendrocyte unit comprised the oligodendrocyte cell body, processes and the internodal myelin segments they support. Oligodendrocyte units corresponded to classically described type I/II or type III/IV unit phenotypes which respectively myelinated discrete populations of small and large diameter axons, delineated by a myelinated fire diameter of 2-4 microns (diameter of the axon plus its myelin sheath). Within units, mean fibre diameter was directly related to mean internodal length and inversely related to the number of myelin sheaths in the unit. The relationship between fibre diameter and internodal length was retained in units which myelinated axons of different diameters, indicating that axon diameter was an important determinant of the longitudinal dimensions of myelin sheaths. We also show that type III/IV units maintained a far greater volume of myelin than type I/II units. It was concluded that type I/II and III/IV oligodendrocytes represent two functionally and morphologically distinct phenotypes whose distribution densities were determined by the diameter and spatial dispersion of axons.

Age Factors↗
PubMed1997

Functional differences among the six Saccharomyces cerevisiae tRNATrp genes.

The Saccharomyces cerevisiae haploid genome includes six copies of the gene encoding tRNATrp which are scattered on five chromosomes. Other, non-functional tDNATrp fragments also occur in the genome. The segments of all six genes which encode the 72-nucleotide mature tRNATrp, as well as a 34-nucleotide intervening sequence, are identical. However, the 5' and 3' flanking sequences diverge virtually at the boundaries of the coding region. We have used an assay based on suppression of UGA mutations by multi-copy clones of tDNATrp to search for functional differences among these genes. Previous studies with one tDNATrp had demonstrated that moderate suppression of a UGA mutation, leu2-2, resulted from introduction of a multi-copy clone of the gene. Attempts to use this assay to select tDNATrp clones from a yeast genomic library yielded only four of the six different clones. The other two genes were amplified by PCR and cloned in pRS202, a 2 mu vector also used for the genomic library. Plasmids bearing the six tRNA genes were transformed into S. cerevisiae strain JG369.3B and scored for their ability to suppress the leu2-2 mutation as well as his4-260, another UGA marker. Two of the six tRNATrp clones were unable to suppress either marker, two evidenced weak suppression of the Leu auxotrophy, and two were able to suppress both markers. Growth rates in liquid media requiring suppression were measured for cell lines carrying each of the clones. Differences greater than 50-fold were observed in media lacking histidine. An evolutionary tree based on 5'-flanking sequence corresponds reasonably well with suppressor activity, while a similar analysis of 3'-flanking sequence does not. This suggests that the functional differences are based on divergence in the 5'-flanking sequences of the tRNATrp genes.

Base Sequence↗
PubMed1997

PDGF-alpha receptor and myelin basic protein mRNAs are not coexpressed by oligodendrocytes in vivo: a double in situ hybridization study in the anterior medullary velum of the neonatal rat.

Platelet-derived growth factor (PDGF) is a growth-regulatory dimer with A and B subunits. PDGF-AA, acting via PDGF receptors of the alpha-unit subtype (PDGF-alphaR), is implicated in the differentiation of oligodendrocyte precursors and in the survival of newly formed oligodendrocytes, which gradually lose expression of PDGF-alphaR. However, it is unclear whether terminally differentiated oligodendrocytes express PDGF-alphaR in vivo. To address this question, and to help clarify the role of PDGF-AA in late oligodendrocyte differentiation, we have used double in situ hybridization with digoxigenin- and fluorescein-labeled riboprobes to relate PDGF-alphaR mRNA and myelin basic protein (MBP) mRNA expression in the isolated intact anterior medullary velum (AMV) of rats ages Postnatal Day (P) 10-12 and P30-32. In parallel experiments, AMV were immunolabeled with the oligodendrocyte-specific monoclonal antibody Rip to provide information on oligodendrocyte development and the extent of myelination. At P10, the AMV contained tracts in which axons ranged from unmyelinated to fully myelinated, whereas myelination was complete in P30-32 AMV. The first oligodendrocytes to express MBP mRNA or Rip were promyelinating oligodendrocytes, which had a "star-burst" morphology and had not yet begun to form myelin sheaths. As myelination proceeded, MBP mRNA became dispersed throughout oligodendrocyte units, comprising cell somata, processes, and internodal myelin sheaths. By P30-32, MBP mRNA had been redistributed to the myelin sheaths only, reflecting a change in the site of protein synthesis in mature myelinated axon tracts. At no stage of oligodendrocyte differentiation did we observe cellular coexpression of mRNA for PDGFalphaR and MBP. Our results indicated that oligodendrocytes lost the expression of PDGFalphaR prior to gaining that of myelin gene products, and preclude an action of PDGF-AA on Rip+/MBP+ star-burst promyelinating oligodendrocytes. The spatial and temporal expression of PDGF-alphaR mRNA in the AMV was inversely related to the pattern of maturation of both myelin and oligodendrocytes, and is consistent with PDGF-alphaR being expressed by pro-oligodendrocytes. A notable finding was the high level of expression of PDGF-alphaR mRNA in the AMV of juvenile rats, localized to cell bodies within the myelinated axon tracts, strongly suggesting that oligodendrocyte precursors persisted in the mature velum.

Animals↗
PubMed1997

The relationship between developing oligodendrocyte units and maturing axons during myelinogenesis in the anterior medullary velum of neonatal rats.

Myelinogenesis was investigated in whole-mounted anterior medullary vela from rats aged postnatal day (P) 10-12, using double immunofluorescence labelling with Rip and anti-neurofilament 200 (NF200) antibodies, to identify oligodendrocytes and axons, respectively. A number of discrete phases of maturation of oligodendrocyte units were recognised. (1) Promyelinating oligodendrocytes co-expressed Rip and Myelin basic Protein and formed axonal associations, prior to ensheathment. (2) Transitional oligodendrocytes contained both ensheathing and non-ensheating processes. (3) Myelinating oligodendrocytes were established after a period of remodelling (in which non-ensheathing processes were lost), appearing as oligodendrocyte unit morphological phenotypes with a definitive number of incipient myelin sheaths. (4) Maturation of myelinating oligodendrocytes was defined as the establishment of internodal sheath lengths and the redistrubution of myelin basic protein from the cell somata and radial processes into the myelin sheaths only. Myelination was probably related to the maturational state of the axons, since it was initiated when the latter had attained a critical diameter of between approximately 0.2 and 0.4 micron, coincident with the expression of NF200. Oligodendrocyte differentiation and myelination of the AMV were asynchronous and multifocal, and at P10: (1) axons which were destined to be of the largest calibre in the adult AMV were already myelinated by early developing oligodendrocytes, whilst those which were destined to be the smallest calibre in the adult were unmyelinated, but ultimately became ensheathed by late developing oligoendrocytes; (2) axons were sequentially ensheathed by early developing myelinating oligodendrocytes and late developing promyelinating oligodendrocytes; (3) all axons were small calibre; (4) oligodendrocyte units exhibited polymorphism. Thus, the development of oligodendrocyte morphological phenotypes was not related solely to either the physical dimension of axon calibre at the time of ensheathment, nor oligodendrocyte birth dates.

Animals↗
PubMed1997

Japanese Biliary Atresia Registry, 1989 to 1994.

The Japanese Biliary Atresia Society founded in 1980 for the aim of investigations of all aspects of biliary atresia (BA), started a nationwide registry of BA patients in 1989. A total of 626 cases were registered from 1989 to 1994. The male to female ratio was 0.58. Corrective surgery was performed in 603 patients. Regarding the type of obstruction, 63 cases were Type I, atresia of the common bile duct, 9 were Type II, atresia of the hepatic ducts, and 543 were Type III, atresia of the porta hepatis. As initial corrective procedures, original Roux-en Y, Suruga II and Roux-en Y with intestinal valve were mainly employed. Jaundice cleared in 346 patients (57%) and decreased in 131, while it persisted in 120. The 5-year-follow-up showed that 34 patients, 49% of the patients who were followed up, were alive without jaundice, while 28 (41%) are dead. Thirty five, 33% of the patients who were entered to the Registry, were lost to follow-up.

Biliary Atresia↗
PubMed1997

Oronasal leishmaniasis caused by a parasite with an unusual isoenzyme profile.

A 45-year-old Sudanese man from western Sudan presented with oronasal leishmaniasis of three years duration. He had no history of previous kala-azar or cutaneous leishmaniasis. The parasite isolated from the oral mucosa was characterized by isoenzymes using 12 enzymes and by polymerase chain reaction amplification of kinetoplast DNA using species-specific primers. The specific primers gave products indistinguishable from those of the Leishmania donovani complex. However, the isoenzyme profile showed a zymodeme pattern that was significantly different from the zymodemes previously reported in the Sudan and the Ethiopian region.

Animals↗
PubMed1996

Transfer of horseradish peroxidase from oligodendrocyte to axon in the myelinating neonatal rat optic nerve: artefact or transcellular exchange?

In this paper we make the surprising observation that intracellular injection of horseradish peroxidase (HRP) into a single myelinating oligodendrocyte also resulted in localised HRP labelling at the nodes of Ranvier of some axons of the unit. It appeared that HRP had been transferred to the nodal axoplasm from the paranodal loops of the HRP-filled oligodendrocyte. Three HRP-filled oligodendrocytes from isolated optic nerves of 14-day-old rats were analysed by serial section electron microscopy, and HRP was observed in the axonal cytoplasm at three of the nodes of Ranvier delineated by one of the cells. At labelled nodes, HRP was of a uniform intensity throughout the nodal axoplasm. Axonal labelling gradually diminished along the paranodal regions and was not evident in the contiguous internodal axoplasm beyond 20 microns from the node. The myelin sheaths, paranodal loops, and axons appeared normal at labelled nodes, and the paranodal loops and astrocyte perinodal processes adjacent to those of the HRP-filled oligodendrocyte unit did not contain HRP. There was no evidence of extracellular HRP or tissue damage in the surrounding neuropil, and axons neighbouring those enwrapped by the HRP-filled oligodendrocyte did not contain HRP. The possibility that axonal labelling was an artefact of either iontophoretic injection or tissue preparation is discussed. This provocative finding is not definite proof of exchange, but the balance of evidence supports the possibility that there was transcellular exchange of HRP at paranodes between the labelled oligodendrocyte and some of the axons in the unit. The rarity of HRP transfer to axons suggests that it may be a transient or labile event. It is not clear whether oligodendrocyte to axon macromolecular exchange has real physiological and/or pathological significance.

Animals↗
PubMed1996

Current status of 21 patients who have survived more than 20 years since undergoing surgery for biliary atresia.

Between 1952 and 1993, 289 patients with biliary atresia underwent surgery at the authors' institution. Twenty-two of them survived more than 20 years; one has since died of hepatic failure (at age 28 years). Of the 21 current survivors (age range, 20 to 39 years), 13 underwent hepatic portoenterostomy; the others had hepaticoenterostomy. None of these patients has undergone liver transplantation. Sixteen patients have led near-normal lives. This includes three married women, one of whom has given birth to a healthy baby boy. Of the six patients who had portal hypertension, three underwent both splenectomy and proximal splenorenal shunting in or before 1985. None of these patients has required additional treatment for portal hypertension. The quality of life of one patient has been severely affected by an unrelated condition (Turner's syndrome). A 22-year-old man was diagnosed as having intrahepatic stones 3 years ago. In another 22-year-old man, hepatic dysfunction developed after frequent episodes of cholangitis. He is now being considered for liver transplantation. The majority of the long-term survivors have good quality of life. However, a few continue to suffer from complications including recurrent cholangitis. Close long-term postoperative follow-up is required for patients with biliary atresia.

Adult↗
PubMed1996

Activity of artemether-azithromycin versus artemether-doxycycline in the treatment of multiple drug resistant falciparum malaria.

The efficacy of the combination of artemether with doxycycline or azithromycin was evaluated in 60 patients with acute uncomplicated falciparum malaria who attended malaria clinic in Mae Sot, Tak Province (Thai-Myanmar border). Patients (30 each) were randomized to receive (a) 300 mg artemether together with 100 mg doxycycline as initial doses, followed by 100 mg artemether plus 100 mg doxycycline at 12 hours later, then 100 mg doxycycline every 12 hours for another 4 days, or (b) 300 mg artemether together with 500 mg azithromycin, followed by 250 mg azithromycin at 24 and 48 hours. The follow-up period was 28 days. Patients in either group had a rapid initial response to treatment with comparable PCT and FCT. The cure rate of artemether-azithromycin regimen was significantly lower than that of artemether-doxycycline regimen (14.8 vs 53.3%). Low cure rate from artemether-azithromycin combination in this study was likely to be due to inadequate azithromycin dosage. However, with the low incidence of gastrointestinal adverse effects, the once daily dose of azithromycin could still be increased in order to enhance its clinical efficacy. The simplicity of drug administration and lesser incidence of adverse effects make azithromycin a more proper partner of artemether than doxycycline. Further dose-finding and pharmacokinetic study with the artemether-azithromycin combination is encouraging.

Adolescent↗
PubMed1995

[Rheumatic fever, a disease undergoing change, based on the experience of the past 15 years].

The authors reviewed the records of paediatric patients treated at the cardiology department of the Svábhegyi Gyermekgyógyintézet during the period from 1 January 1979 to 31 December 1993. All the patients elected for the survey had rheumatic fever and represented about 20 percent of the national patient pool. Among the 62 children referred for suspected rheumatic fever 26 had carditis, and 3 suffered from pancarditis. Two children had chorea minor with carditis and there were 2 additional cases with chorea minor only. Valvular heart disease has developed in 21 patients. There were 16 patients with mitral regurgitation, these conditions have occurred in combination with mitral stenosis in 3 cases, whereas the insuffitientia of the aortic valve developed in two patients. The authors analysed the clinical signs of the patients and established that the chronic syndromes came in front. The authors have observed a favourable trend in the epidemiology of the disease, in particular, while 34 patients were referred during the first 5 years, there were only 18 cases in the second 5-years period. During the interval from 1989 to 1993, only 10 children with rheumatic fever have been referred to or treated at the authors' institute.

Adolescent↗
PubMed1995

Cavernous lymphangioma of the breast: case report of an infant.

Ultrasonography and magnetic resonance imaging (MRI) were used to assess a 4-month-old male infant with a multicystic tumor of the left breast that was identified at birth. The tumor was removed surgically following the diagnosis of a cavernous hemangioma. Only seven similar cases of lymphangioma of the breast have been reported. We review these cases in conjunction with our own findings.

Breast Neoplasms, Male↗
PubMed1995

Biochemical subtypes of oligodendrocyte in the anterior medullary velum of the rat as revealed by the monoclonal antibody Rip.

Oligodendrocytes were studied in the anterior medullary velum (AMV) of the rat using the monoclonal antibody Rip, an oligodendrocyte marker of unknown function. Confocal microscopic imaging of double immunofluorescent labelling with antibodies to Rip and carbonic anhydrase II (CAII) revealed two biochemically and morphologically distinct populations of oligodendrocyte which were either Rip+CAII+ or Rip+CAII-. Double immunofluorescent labelling with Rip and myelin basic protein (MBP) or glial fibrillary acidic protein (GFAP) provided direct evidence that Rip-labelled cells were phenotypically oligodendrocytes and confirmed that Rip did not recognise astrocytes. Oligodendrocytes which were Rip+CAII+ supported numerous myelin sheaths for small diameter axons, whilst Rip+CAII- oligodendrocytes supported fewer myelin sheaths for large diameter axons. Morphologically, Rip+CAII+ oligodendrocytes corresponded to types I or II of classical nomenclature, whilst Rip+CAII- oligodendrocytes corresponded to types III and IV. The results demonstrated a biochemical difference between oligodendrocytes which myelinated small and large diameter fibres.

Animals↗