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Biomedical subjects

A Ibrahim

Publications and source records attributed to A Ibrahim.

At least 55 records · Page 3Linked to original sources
PubMed1997

Value of cytomegalovirus detection by PCR in bronchoalveolar lavage routinely performed in asymptomatic bone marrow recipients.

In order to compare PCR with rapid virus culture for the early detection of CMV in bronchoalveolar lavage (BAL) after bone marrow transplantation, 26 asymptomatic patients were routinely evaluated for the presence of CMV on day 35 using these two techniques. Concurrent blood samples were also analyzed in all cases. CMV was detected synchronously by both culture and PCR in six of 26 (23%) BAL and in five of 26 (19%) blood specimens. Among these positive specimens, three BAL and blood samples were positive in the same patients. Five (19%) BAL and five (19%) blood samples were culture-negative but PCR-positive. No BAL or blood specimens were positive by culture alone. When considering matched BAL-blood samples, five were positive in only one fluid, BAL (n = 3) or blood (n = 2) using culture, while seven were positive in only one fluid, BAL (n = 4) or blood (in = 3) using PCR. Overall, six of 26 (23%) patients had culture-negative but PCR-positive results. Three of these six patients were positive only in BAL and two of them subsequently received antiviral therapy for development of symptoms suggestive of CMV infection. We suggest that asymptomatic patients with negative-culture but PCR-positive results on day 35 in BAL should be subsequently closely monitored for the presence of CMV.

Adult↗
PubMed1997

Should cytomegalovirus be tested for in both blood and bronchoalveolar lavage fluid of patients at a high risk of CMV pneumonia after bone marrow transplantation?

To identify and treat patients at high risk of cytomegalovirus (CMV) pneumonia after bone marrow transplantation (BMT), we tested for CMV viraemia weekly, and performed broncho-alveolar lavage (BAL) on day 35 post-transplant in 63 recipients. 36 allogeneic BMT recipients were at a high risk of CMV pneumonia (25 CMV-seropositive recipients and 11 patients receiving marrow from a CMV-seropositive donor). Patients with a positive BAL or viraemia received a 14 d course of ganciclovir or foscarnet. CMV was detected in 29 (46%) of the 63 BMT recipients and excretion of CMV in blood and BAL was significantly linked. However, among the 29 patients who excreted the virus, only 10 (35%) shed CMV in blood and BAL at the same time: 19 patients (65%) had detectable CMV in blood (11 patients) or BAL (eight patients) only. Therefore, on the basis of viraemia or BAL alone, 21/29 patients (70%) and 18/29 patients (60%), respectively, would have received antiviral treatment. BAL increased the CMV detection rate by 13% (8/63 patients) relative to viraemia. With this strategy, the incidence of CMV pneumonia was reduced to 3% in allografted patients. Only two of the 19 autografted patients developed fatal CMV pneumonia. We avoided anti-CMV treatment in 54% of all the BMT recipients. In conclusion, CMV should be tested for in both blood and BAL fluid of BMT recipients at high risk of CMV pneumonia.

Bone Marrow Transplantation↗
PubMed1997

Phylogenetic relationship of the twenty-one DNA groups of the genus Acinetobacter as revealed by 16S ribosomal DNA sequence analysis.

The inter- and intrageneric relationships of members of the genus Acinetobacter were investigated by performing a comparative sequence analysis of PCR-amplified 16S ribosomal DNAs (rDNAs) from 21 strains representing all of the DNA groups that have been described. Phylogenetic treeing confirmed that Acinetobacter spp. form a coherent cluster within the gamma subdivision of the class Proteobacteria that includes strains with overall levels of 16S rDNA sequence similarity of more than 94%. The analysis of intrageneric relationships suggested that the majority of the strains cluster in five clearly distinguishable clusters, and this conclusion was supported by the results obtained with the different methods used for phylogenetic analysis (i.e., the maximum-likelihood, parsimony, and distance matrix methods). The first cluster contains the representatives of DNA groups 2 (Acinetobacter baumannii) and TU13, whereas the second cluster comprises representatives of DNA groups 3, "Close To TU13," and "between 1 and 3." The representatives of closely related Acinetobacter DNA groups 8 (Acinetobacter twoffii) and 9 belong to the third cluster, which includes the representative of DNA group 6 as well. The fourth cluster is formed by DNA groups BJ15, BJ16, and BJ17, and the fifth cluster comprises DNA groups 1 (Acinetobacter calcoaceticus), BJ14, 10, and 11. Within the fifth cluster the 16S rDNA sequences of DNA group 10 and 11 strains are nearly identical. The representatives of DNA groups 4 (Acinetobacter haemolyticus), 5 (Acinetobacter junii), 7 (Acinetobacter johnsonii), 12 (Acinetobacter radioresistens), TU14, and TU15 form individual branches that are not significantly affiliated with any of the five clusters identified. Apart from the clustering of the most closely related DNA groups, the general topology of the distance dendrogram revealed some discrepancy with previous DNA-DNA hybridization data, which may point to the inadequacy of comparative 16S rDNA sequence analysis for reflecting true evolutionary relationships of closely related bacterial taxa. Important, however, was the presence of unique sequence motifs in each of the 21 different DNA groups studied, which may be useful for rapid differentiation of DNA groups of the genus Acinetobacter.

Acinetobacter↗
PubMed1997

Development of a highly specific assay for rapid identification of pathogenic strains of Yersinia enterocolitica based on PCR amplification of the Yersinia heat-stable enterotoxin gene (yst).

The chromosomal gene yst, which encodes a heat-stable enterotoxin of Yersinia enterocolitica, is a useful diagnostic marker because it occurs only in invasive strains of this species. A homologous gene also occurs in some strains of Yersinia kristensenii. Sequence analysis of the yst genes from two different strains of Y. enterocolitica and from Y. kristensenii revealed a substantial number of mismatches at the 3' ends of the yst genes of the so-called American and European biotypes of Y. enterocolitica. Moreover, several mismatches and a deletion of 5 codons were found in the yst of Y. kristensenii. These findings were used to develop a PCR-based assay for yst of Y. enterocolitica which yielded a detectable product in as little as 50 min. The assay was 100% specific in terms of its ability to identify potentially pathogenic strains of Y. enterocolitica regardless of biotype or serotype. The PCR yielded an amplicon that was visible on agarose gel electrophoresis from as few as 100 CFU, or 10 CFU when the PCR was combined with dot blot hybridization with a digoxigenin-labeled oligonucleotide probe that corresponded to an internal sequence of yst. These results establish the value of the yst gene as a target for the identification of pathogenic bioserotypes of Y. enterocolitica and the usefulness of PCR for this purpose.

Amino Acid Sequence↗
PubMed1997

Hepatic veno-occlusive disease after myeloablative treatment and bone marrow transplantation: value of gray-scale and Doppler US in 100 patients.

PURPOSE: To determine the value of gray-scale ultrasonography (US) and Doppler US in the prediction, diagnosis, and prognostic assessment of hepatic veno-occlusive disease (HVOD). MATERIALS AND METHODS: One hundred patients (median age, 22 years; range, 18 months to 59 years) receiving total body irradiation or busulfan therapy as intensive treatment before hematopoietic stem cell transplantation were studied prospectively. Each patient underwent gray-scale and Doppler US examination before transplantation and weekly thereafter while hospitalized (about four examinations per patient). Seven gray-scale morphologic criteria and seven Doppler criteria were studied, yielding three individual scores: gray-scale score, Doppler score, and total score. RESULTS: Twenty-five patients developed HVOD; nine of these patients died. Positive predictive values of the 14 criteria were 31%-95%, and negative predictive values were 85%-96%. The three scores correlated with the clinical diagnosis of HVOD. Depending on the cutoff value, the positive predictive value of the total score was 44%-89% and the negative predictive value was 91%-98%. The gray-scale and Doppler criteria differed significantly between patients with HVOD and those with graft-versus-host disease of the liver (P = 10(-4)). CONCLUSION: Even if there is overlap in findings between patients with and those without HVOD, gray-scale and Doppler US are valid for positive and differential diagnosis and have predictive and prognostic relevance.

Adult↗
PubMed1996

Detection of Cryptosporidium parvum in raw milk by PCR and oligonucleotide probe hybridization.

Cryptosporidium spp. are potential contaminants of food. Suspected cases of food-borne cryptosporidiosis are rarely confirmed because of the limited numbers of oocysts in the samples and the lack of sensitive detection methods adaptable to food. PCR was investigated as a means of overcoming this problem. A PCR assay was designed for the specific amplification of a previously sequenced portion of an oocyst protein gene fragment of Cryptosporidium parvum (N. C. Lally, G. D. Baird, S. J. McQuay, F. Wright, and J. J. Oliver, Mol. Biochem. Parasitol. 56:69-78, 1992) and compared with the primer set of Laxer et al. (M. A. Laxer, B. K. Timblin, and R. J. Patel, Am. J. Trop. Med. Hyg. 45:688-694, 1991). The PCR products were hybridized with digoxigenin-labeled internal probes and detected by chemiluminescence to enhance sensitivity. The two sets of primers were compared with regard to their sensitivity and specificity by using a variety of human and animal isolates of C. parvum and related parasites. Both assays enabled the detection of 1 to 10 oocysts in 20 ml of artificially contaminated raw milk. The assay based on the PCR set and probe of Laxer et al. detected DNAs from Eimeria acervulina and Giardia intestinalis. The new assay has good specificity for C. parvum bovine isolates and hence has a better potential for monitoring the prevalence of C. parvum in raw milk and other environmental samples.

Animals↗
PubMed1996

Amplification and restriction endonuclease digestion of a large fragment of genes coding for rRNA as a rapid method for discrimination of closely related pathogenic bacteria.

By use of primers specific to conserved regions of the rRNA gene cluster, a discrete amplicon of approximately 5 kb was amplified by PCR from all 21 bacterial genera investigated. Subsequent endonuclease digestion of the PCR product with HaeIII distinguished between the three species of the human pathogen Francisella spp. on the one hand and four clinically relevant genomic groups of Acinetobacter spp. on the other hand. The described technique has the potential as a rapid method for discriminating between closely related species that are of clinical importance.

Acinetobacter↗
PubMed1996

Biomphalaria glabrata: a new threat for schistosomiasis transmission in Egypt.

This is the first report on the infestation of irrigation and drainage systems at Giza, Qalyoubiya and Kafr El Shiekh Governorates, with Biomphalaria glabrata (the snail host of Schistosoma mansoni in the new world). Identification of this snail species was based on morphometry of the shell, shape of the radular lateral teeth and presence of the characteristic renal ridge. B. glabrata snails collected from natural water courses in Egypt proved to be susceptible to a local strain of S. mansoni. These snails were infected by 52% versus 75% for Biomphalaria alexandrina (the only local host) under the same laboratory conditions. Meanwhile the periodic total cercarial production was higher in B. glabrata than in B. alexandrina (252 +/- 110 cercariae/snail versus 203 +/- 86 cercariae/snail, respectively). Differences in infection rate, length of schistosome incubation period, duration of cercarial shedding and cercarial production in various sizes of the two snail species are reported and discussed.

Animals↗
PubMed1996

Filtration, centrifugation and mouse exposure for the detection of schistosome cercariae in water.

Three methods for detection of schistosome cercariae in water were studied under laboratory and simulated field conditions in Egypt. Water samples tested by filtration and centrifugation quantitatively reflected the density of cercariae in moderately turbid canal water (30 Nephelometry Turbidity Unites, NTU). When tested in waters of increasing turbidity, the centrifuge gave more consistent results than the filtration system. The centrifugation technique was more efficient in processing the water samples and took almost half the time of filtration. Mouse exposure was useful in detecting cercariae, but was not quantitative. However, there was a significant improvement in worm recovery when mice were more close together in the floatation device. Mouse exposure was also expensive and cumbersome to use. It appears from the present results that the technique of choice for further cercariometric work under Egyptian conditions may be centrifugation.

Animals↗
PubMed1996

Protein-losing gastropathy associated with cytomegalovirus: a rare and late complication of allogeneic bone marrow transplantation.

A 36-year-old women with chronic myelogenous leukemia in first chronic phase received a bone marrow transplant from her HLA-identical brother. The preparatory regimen consisted of total body irradiation (10 Gy) and cyclophosphamide (60 mg/kg for 2 days). Full engraftment was achieved and the woman was monitored as an outpatient after discharge from hospital on day 35. One year after BMT, while she was on cyclosporin A and steroids because of chronic graft-versus-host disease, the patient developed protein-losing gastropathy associated with cytomegalovirus infection (with no gastrointestinal symptoms), which regressed spontaneously in 4 weeks.

Adult↗
PubMed1996

Cercariometry in the study of Schistosoma mansoni transmission in Egypt.

The recovery of Schistosoma mansoni cercariae was studied in experimental ditches and natural irrigation canals using a continuous operating centrifuge and a water suction sampling technique. Recovery of cercariae from static water in the ditches where caged infected Biomphalaria alexandrina snails were placed showed that cercariae recovered were more with increase of infected snails and decrease of water volume and were most abundant in the proximity of the snails which produced them. Shade or heavy vegetation cover reduced the recovery of cercariae. Results suggest also strong seasonal differences in diurnal patterns of cercarial recovery. An early morning peak with large number of cercariae occurred during hot weather while in cooler seasons cercariae appear in fewer numbers but persist for most of the day. Obtained information, beside contributing to knowledge of cercarial behaviour, should help to optimize taking water sample and consequently to increase efficiency of cercariometry techniques. In the natural irrigation system, cercariometry was significantly more sensitive in detecting transmission foci than snail sampling by a dip net.

Animals↗
PubMed1996

Effect of adamantylamide dipeptide on reinfection resistance after primary infection eradication in experimental Schistosomiasis mansoni.

The immunomodulatory effect of adamantylamide dipeptide (AdDP) was tested in Schistosoma mansoni-infected challenged mice and infected praziquantel-treated (2 x 500 mg/kg) challenged animals. In AdDP-treated mice, the drug was given 58 days post infection of mice with 120 S. mansoni cercariae, challenged with 240 cercariae one day after treatment, while in praziquantel-treated mice, the drug was given 44 days post infection, two weeks post treatment (58 days post infection) they were given AdDP in the same dose and one day later challenged with the same cercarial load. AdDP increased the resistance against reinfection (90.3% vs. 83.5% in infected challenged control). The significant increase in resistance against reinfection was accompanied by significant increase in the percentage of lymphocytes forming EAC rosettes. Mice cured of their primary infection by praziquantel showed a significant reduction in percent resistance, hepatic granuloma size and intragranulomal Thy+ 1,2 and Lyt+ 1 T cells. In mice treated with both praziquantel and AdDP, resistance to reinfection was significantly higher than in mice treated with praziquantel only (89.29% vs. 62.13%) reaching a level comparable to that recorded in infected-challenged controls. Meanwhile granuloma size was not significantly different from that in the infected-challenged controls with a significant rise in Lyt+ 1 T cells. Data may suggest a role for granuloma as a mechanical obstacle and/or as a T cell-mediated reaction in maintenance of resistance to reinfection. A role for B lymphocytes should be considered as the rise of percent resistance to reinfection in mice treated with AdDP alone was accompanied by a significant increase in the percentage of B lymphocytes forming EAC rosettes. Moreover, findings may suggest the use of AdDP together with specific chemotherapy in endemic areas where reinfection and repeated treatment with its consequences are of common occurrence.

Adjuvants, Immunologic↗
PubMed1996

Shape optimisation of a Charnley prosthesis based on the fatigue notch factor.

The femoral component of the artificial hip joint implanted in a patient's femur is subjected to a complex set of forces exerted due to normal life activities. It is thought that high values of stress in the cement in a cemented prosthesis can lead to fractures of the cement mantle and loosening of the stem. The incidence of such problems may be diminished by reduction of the fatigue notch factor in the cement, such that stress concentrations are avoided and the crack initiation time maximised. This study describes a method for numerical shape optimisation to determine an optimal shape for the femoral stem of a hip prosthesis in order to minimise the fatigue notch factor in the cement layer at the interfaces with the bone and stem whilst at the same time maintaining or increasing the stress levels in the proximal medial femoral bone to help prevent stress shielding. The method when used to optimise the shape of a stainless steel Charnley stem was found to be extremely efficient and effective. The resulting optimal shape was heavily waisted in the proximal region below the neck but distally was quite similar to the original design. The fatigue notch factors in the cement were reduced by 16% and 19% for medial and lateral cement/stem interfaces, respectively, and by 8% and 2% for the corresponding cement/bone interfaces. The fatigue notch factor in the proximal medial bone was increased by 57% which indicates that the general stress level in this region is markedly increased. Thus the optimised design should increase the fatigue life of the cement and at the same time reduce stress shielding in the proximal bone. Both of these effects may help prevent loosening of the femoral component and hence reduce the need for early revision operations.

Aged↗
PubMed1996

Serum interleukin-12 levels in patients undergoing allogeneic or autologous bone marrow transplantation.

Cytokines may be helpful in promoting hematopoietic reconstitution but have also an impact on the cellular interactions that contribute to GvHD and immunologic graft rejection. Because IL-12 is emerging as a central cytokine in immune response, we have investigated its levels in serum samples of patients undergoing bone marrow transplantation and transplant-related events. A double-antibody radioimmunoassay method for monitoring levels of endogenous IL-12, before and after allogeneic (27 patients) or autologous (19 patients) bone marrow transplantation, was used. The serum levels of IL-12 after allogeneic BMT were found to be relatively low (140-300 pg/ml) and similar to the IL-12 levels in the healthy donors (183 pg/ml). Seric IL-12 levels following autologous BMT (350 pg/ml) were higher than those observed in patients receiving an allogeneic BMT and in healthy donors. Our data indicate that the occurrence of GvHD and the development of infection after allogeneic BMT are not associated with IL-12 induction which suggests a possible down-regulation due to immunosuppressive treatment.

Adolescent↗
PubMed1995

A mating type-linked mutation that disrupts the uniparental inheritance of chloroplast DNA also disrupts cell-size control in Chlamydomonas.

An intriguing feature of early zygote development in Chlamydomonas reinhardtii is the active elimination of chloroplast DNA from the mating-type minus parent due presumably to the action of a zygote-specific nuclease. Meiotic progeny thus inherit chloroplast DNA almost exclusively from the mating-type plus parent. The plus-linked nuclear mutation mat3 prevents this selective destruction of minus chloroplast DNA and generates progeny that display a biparental inheritance pattern. Here we show that the mat3 mutation creates additional phenotypes not previously described: the cells are much smaller than wild type and they possess substantially reduced amounts of both mitochondrial and chloroplast DNA. We propose that the primary defect of the mat3 mutation is a disruption of cell-size control and that the inhibition of the uniparental transmission of chloroplast genomes is a secondary consequence of the reduced amount of chloroplast DNA in the mat3 parent.

Animals↗
PubMed1995

High-dose chemotherapy followed by hematological support: experience in the treatment of germ cell tumors.

Etoposide, bleomycin, and cisplatin based combination chemotherapy (BEP) and the surgical removal of residual disease is the standard treatment of metastatic germ cell tumors (GCT). Standard treatment including three cycles of BEP for good risk patients and four cycles of BEP for poor risk patients allows 95 and 65% cure rates in these groups respectively. However, about 10% of patients achieving CR after first line therapy eventually relapse. Conventional second line treatment (VeIP) includes a combination of vinblastin, ifosfamide and cisplatin or (VIP) with etoposide replacing vinblastin for patients pretreated by noncontaining etoposide chemotherapy regimens. These protocols induce a 60% CR rate and a 20-30% long term nonevolutive disease (NED) rate. Trials with high-dose chemotherapy (HDCT) and autologous hematopoietic stem cell transplantation (AHSCT) have been undertaken during the past decade. The main experiences were obtained with combinations of etoposide, platin derivatives, and either cyclophosphamide or ifosfamide. The majority of studies concerned heavily pretreated patients. Few studies have included HDCT and AHSCT as part of consolidation first line treatment for poor risk patients. A randomized multicenter French trial showed no significant benefit of this procedure (Droz, ASCO 1992). In refractory patients, HDCT and AHSCT induces a potential of 10% NED rate and this appears to be the maximum effect that can be obtained. An analysis of prognostic factors at first salvage chemotherapy revealed four adverse factors: high serum levels of HCG (> 10,000 mIU/ml) or AFP (> 1,000 g/ml); extragonadal origin; presence of lung metastases at salvage; and an incomplete response to first line treatment. Three prognostic groups have been defined according to a combination of these variables (Droz, Kramar, ASCO 1993). The use of HDCT followed by AHSCT as consolidation salvage treatment seems more promising since 25-45% of patients have long-term NED. It can be assumed that this procedure may increase the long term NED rate by 20% and produce a success rate up to 40%, but further studies are warranted in this setting. In order to evaluate HDCT with AHSCT rescue, an international randomized study has been undertaken in relapsed or first partial remission GCT patients. Randomization is stratified according to the three prognostic groups previously defined. Salvage regimens for eligible patients include two cycles of PEI or VeIP and in case of response, two more cycles of the same protocol (arm A) or one more cycle of PEI or VeIP followed by HDCT (CarboPEC: carboplatin, etoposide, and cyclophosphamide) (arm B).(ABSTRACT TRUNCATED AT 400 WORDS)

Antineoplastic Combined Chemotherapy Protocols↗