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Biomedical subjects

A Nassar

Publications and source records attributed to A Nassar.

At least 19 recordsLinked to original sources
PubMed2002

Investigation into a cluster of infant deaths following immunization: evidence for methanol intoxication.

A cluster of infant deaths due to severe metabolic acidosis following immunization was reported in a prosperous farming village in Egypt. Fears that more deaths might occur, and of a deleterious effect on national immunization programs prompted an urgent investigation by national and international partners. The deaths, and other previously unrecognized illness following immunization, were associated with excessive topical application of methanol. Methanol was employed as an anti-pyretic and anti-inflammatory agent following injections. Fear of adverse reactions to vaccine had encouraged increasing use of methanol for these purposes. Local physicians and nurses were unaware of the toxicity of methanol and did not consider it in the differential diagnosis, and thus did not offer appropriate life-saving therapy. The interaction of traditional practices and modern medical interventions can have clinically important consequences, and should be considered when programs are introduced and as they are monitored.

Cohort Studies↗
PubMed2002

A unilateral twin extrauterine pregnancy occurring in a solitary fallopian tube: therapeutic choices.

A unilateral twin tubal pregnancy occurring in a solitary fallopian tube is presented. The gynecological history was notable for a previous extrauterine pregnancy in the contralateral fallopian tube and reconstructive surgery to the ipsilateral one. Radical total salpingectomy was performed. The rationale for this management is discussed and different therapeutic alternatives presented.

Adult↗
PubMed2001

Spontaneous umbilical cord hematoma: a rare cause of acute fetal distress.

Spontaneous umbilical cord hematoma is very rare. We present a newborn who was discovered to have a spontaneous fetal umbilical cord hematoma. A nonreassuring fetal heart tracing complicated the first and second stages of labor. The only pathological finding was a short umbilical cord, which could have contributed to the rupture of fetal vessels.

Adult↗
PubMed2000

Elevation of mitochondrial calcium by ryanodine-sensitive calcium-induced calcium release.

Calcium is an important regulator of mitochondrial function. Since there can be tight coupling between inositol 1,4, 5-trisphosphate-sensitive Ca(2+) release and elevation of mitochondrial calcium concentration, we have investigated whether a similar relationship exists between the release of Ca(2+) from the ryanodine receptor and the elevation of mitochondrial Ca(2+). Perfusion of permeabilized A10 cells with inositol 1,4, 5-trisphosphate resulted in a large transient elevation of mitochondrial Ca(2+) to about 8 microm. The response was inhibited by heparin but not ryanodine. Perfusion of the cells with Ca(2+) buffers in excess of 1 microm leads to large increases in mitochondrial Ca(2+) that are much greater than the perfused Ca(2+). These increases, which average around 10 microm, are enhanced by caffeine and inhibited by ryanodine and depletion of the intracellular stores with either orthovanadate or thapsigargin. We conclude that Ca(2+)-induced Ca(2+) release at the ryanodine receptor generates microdomains of elevated Ca(2+) that are sensed by adjacent mitochondria. In addition to ryanodine-sensitive stores acting as a source of Ca(2+), Ca(2+)-induced Ca(2+) release is required to generate efficient elevation of mitochondrial Ca(2+).

Animals↗
PubMed2000

Mutations in exons 9 and 13 of KIT gene are rare events in gastrointestinal stromal tumors. A study of 200 cases.

Gastrointestinal stromal tumors (GISTs), the most common mesenchymal tumors of the gastrointestinal tract, typically express the KIT protein. Activating mutations in the juxtamembrane domain (exon 11) of the c-kit gene have been shown in a subset of GISTs. These mutations lead into ligand-independent activation of the tyrosine kinase of c-kit, and have a transforming effect in vitro. Several groups have studied the clinical implication of the c-kit mutation status of exon 11 in GISTs and a possible relationship between c-kit mutations and malignant behavior has been established. Recently, a 1530ins6 mutation in exon 9 and missense mutations, 1945A>G in exon 13 of the c-kit gene were reported. The frequency and clinical importance of these findings are unknown. In this study we evaluated 200 GISTs for the presence of mutations in exons 9 and 13 of c-kit. Six cases revealed 1530ins6 mutation in exon 9 and two cases 1945A>G mutation in exon 13. All tumors with mutations in exon 9 and 13 lacked mutations in exon 11 of c-kit. None of the analyzed tumors had more than one type of c-kit mutation. All but one of the eight tumors with mutations in exon 9 or 13 of the c-kit gene were histologically and clinically malignant. All four of six cases with exon 9 mutation of which location of primary tumor was known, were small intestinal, suggesting that this type of mutation could preferentially occur in small intestinal tumors. Exon 9 and 13 mutations seem to be rare, and they cover only a small portion (8%) of the balance of GISTs that do not have mutations in exon 11 of c-kit. This finding indicates that other genetic alterations may activate c-kit in GISTs, or that KIT is not activated by mutations in all cases.

Adult↗
PubMed2000

Anti-fasciola IgG isotypes among patients with fascioliasis before and after treatment.

Stool examination using modified Kato thick smear method was performed to detect Fasciola eggs and other parasites. Abdominal pain was the major presenting symptom (83.3%) followed by pallor (71.6%) and fever (16.7%). Anaemia and hepatomegaly were recorded in 70% of patients compared to 25% with splenomegaly. Abdominal ultrasonography revealed hepatomegaly and common bile duct dilatation in 70% of patients. Moreover, 6 cases showed Olympic game rings which is diagnostic. All of patients had positive IgG4 levels, 58 cases were found positive for specific total IgG and IgG1, whereas, only 36 cases had positive IgG2 levels (60%). All negative control group showed no cross reactions. On the other hand, ELISA detecting IgG4 showed the highest specificity (95%), followed by IgG2 (85%) and the least specific test was obtained with detection of IgG (70%) and IgG1 (65%). One week after treatment, 90% of patients were completely cured. One and 3 months after treatment, the cure rate was 83.3%. In completely cured patients, none of anti-Fasciola isotypes was significantly changed.

Adolescent↗
PubMed1999

Modulation of sperm tail protein tyrosine phosphorylation by pentoxifylline and its correlation with hyperactivated motility.

OBJECTIVE: To assess the effect of pentoxifylline on human sperm functions that are crucial to fertilization. DESIGN: Prospective, controlled study. SETTING: Academic tertiary care institute. PATIENT(S): Healthy male sperm donors. INTERVENTION(S): The effects of pentoxifylline (3.6 mM) on hyperactivated motility, sperm binding to the zona pellucida, and sperm protein tyrosine phosphorylation were evaluated. MAIN OUTCOME MEASURE(S): Hyperactivated motility was assessed by computer-assisted motion analysis, and tight binding of sperm to homologous zonae pellucidae was examined using the hemizona assay. Sperm protein phosphorylation was evaluated using indirect immunofluorescence with an antibody to phosphotyrosine (PY20). RESULT(S): Pentoxifylline significantly stimulated hyperactivated motility at 1 hour and 4 hours; it also significantly increased sperm binding to the zona pellucida and enhanced sperm tail tyrosine phosphorylation at 4 hours under capacitating conditions. There was a statistically significant correlation between hyperactivated motility and sperm tail protein phosphorylation. CONCLUSION(S): Pentoxifylline stimulates sperm functions that are essential to achieving fertilization under in vitro conditions in sperm obtained from fertile men. The enhancement of hyperactivated motility is associated with the stimulation of sperm tail tyrosine phosphorylation, suggesting a causal relation and the involvement of a modulatory effect after cyclic adenosine monophosphate-dependent phosphorylation of intermediate proteins.

Fertilization in Vitro↗
PubMed1999

Pentoxifylline stimulates various sperm motion parameters and cervical mucus penetrability in patients with asthenozoospermia.

Pentoxifylline (PTX) was incubated in vitro with human spermatozoa to examine its effects on sperm motility characteristics and bovine cervical mucus penetrability (BCMP). Sperm motion parameters were assessed by computer-assisted motion analysis (CASA) using HTM-IVOS and BCMP was evaluated using the Penetrak kit. In vitro incubation with PTX (1 mg ml-1; 3.6 mM, 30 min) did not significantly change percentage motility, average path velocity (VAP), straight-line velocity (VSL) or beat cross frequency (BCF) of spermatozoa from normozoospermic or asthenozoospermic samples. However, it significantly increased curvilinear velocity (VCL), amplitude of lateral head displacement (ALH) and hyperactivated motility (HA), and significantly decreased linearity (LIN) of spermatozoa from both samples. Pentoxifylline was found to increase BCMP scores for spermatozoa from asthenozoospermic samples, but did not affect scores for spermatozoa from normozoospermic samples. Bovine cervical mucus penetrability (BCMP) was found to be positively and significantly correlated with the percentage motility of both non-PTX-treated and PTX-treated spermatozoa for asthenozoospermic samples. These results demonstrated that PTX enhanced several motion sperm parameters as well as BCMP in asthenozoospermic samples and suggest a potential use of the methylxanthine in infertile patients with motility defects undergoing artificial insemination.

Animals↗
PubMed1999

The relationship between biopsy technique and uncertainty in the histopathologic diagnosis of melanoma.

Review of filed histopathology material of 525 cases of definite melanomas and other atypical pigmented lesions showed that diagnostic certainty was greatest for excisional or deep shave specimens. Shave and particularly punch biopsy specimens were associated with less certainty. The data of this study suggest that punch biopsy should be avoided for pigmented lesions and that a properly done deep shave biopsy is nearly equal to an excision in diagnostic content for such lesions.

Biopsy↗
PubMed1998

Impact of a risk-based prevention policy on neonatal group B streptococcal disease.

OBJECTIVE: Neonatal group B streptococcal infections can be prevented by intrapartum antibiotic prophylaxis. Beginning in 1992, women with obstetric risk factors at University of Miami-Jackson Memorial Medical Center were targeted to receive intrapartum antibiotic prophylaxis. We evaluated these preventive efforts. STUDY DESIGN: A case was defined as isolation of group B streptococci from a sterile site in an infant <7 days old born during the study period, 1992-1995. We reviewed systematic samples of women with preterm delivery and prolonged rupture of membranes to assess use of intrapartum antibiotic prophylaxis. RESULTS: Group B streptococcal cases declined from 1.7 cases/1000 live births to 0.2 cases/1000 live births (Poisson regression, P =.002). Intrapartum antibiotic prophylaxis use increased from 13% of preterm deliveries in 1992 to 42% in 1995, and from 20% of deliveries with prolonged rupture of membranes in 1992 to 72% in 1995 (chi2 test for linear trend P =.007 and P <.001, respectively). CONCLUSION: Provision of intrapartum antibiotic prophylaxis on the basis of risk factors was associated with decreased group B streptococcal disease.

Antibiotic Prophylaxis↗
PubMed1998

Increase of intracellular calcium is not a cause of pentoxifylline-induced hyperactivated motility or acrosome reaction in human sperm.

OBJECTIVE: To investigate the effects of the phosphodiesterase inhibitor pentoxifylline on hyperactivated motility and acrosome reaction in human sperm and to determine whether its stimulatory effects occur via increased intracellular calcium levels. DESIGN: Prospective study. SETTING: Academic tertiary care facility. PARTICIPANT(S): Healthy male donors. INTERVENTION(S): The effects of pentoxifylline on hyperactivated motility, acrosome reaction, and intracellular calcium were studied and compared with the effects of progesterone. Thapsigargin, a known mobilizer of intracellular calcium, also was used as positive control. MAIN OUTCOME MEASURE(S): Hyperactivated motility was assessed by computer-assisted sperm motion analysis using the HTM-IVOS, acrosome reaction was evaluated with the fluorescent probe fluorescein isothiocyanate-labeled Pisum sativum agglutinin, and intracellular calcium was determined by fura-2 using spectrofluorometry. RESULT(S): Pentoxifylline significantly increased both hyperactivated motility and acrosome reaction. Enhancement of hyperactivated motility by pentoxifylline in the capacitation medium persisted for up to 5 hours after pentoxifylline was washed from the medium. It also enhanced the percentage of acrosome-reacted spermatozoa after 4 hours of incubation. These effects occurred in the presence of a marginally significant decrease in intracellular calcium. CONCLUSION(S): Pentoxifylline stimulates hyperactivated motility and acrosome reaction in spermatozoa from fertile men. Its stimulatory effects occur through mechanism(s) other than increase in intracellular calcium.

Acrosome↗
PubMed1998

Plasma membrane integrity of cryopreserved human sperm: an investigation of the results of the hypoosmotic swelling test, the water test, and eosin-Y staining.

OBJECTIVE: [1] To examine the relationship between sperm membrane integrity and motion parameters before and after cryopreservation; [2] to determine the capacity of the membrane integrity tests to predict the outcome of cryopreservation in fertile and infertile men; and [3] to examine the degree of agreement between tail and head membrane integrity of testicular and ejaculated immotile sperm cryopreserved for intracytoplasmic sperm injection. DESIGN: Prospective study. SETTING: Academic tertiary care institution. PATIENT(S): Fertile donors and normozoospermic oligozoospermic, and asthenozoospermic subfertile men. INTERVENTION(S): Semen samples were cryopreserved and thawed for analysis. MAIN OUTCOME MEASURE(S): Sperm membrane integrity and computer-assisted motion parameters. RESULT(S): The hypoosmotic swelling test and water test had a significant and positive correlation in the fresh and cryopreserved ejaculates of all groups. The results of the hypoosmotic swelling test correlated positively with the percent motility in the fresh ejaculates of fertile and subfertile men. None of the membrane integrity tests correlated with the cryosurvival rate in any group. In the ejaculated and testicular samples with no postcryopreservation motility, the simultaneous assessment of hypoosmotic swelling test and eosin showed that of 33% sperm exhibiting coiling with the hypoosmotic swelling test, only 9% were eosin negative, whereas 24% were eosin positive. CONCLUSION(S): [1] The water test may be a simpler replacement for the hypoosmotic swelling test; [2] none of the membrane integrity tests predicted sperm motility after cryopreservation; and [3] there was a high degree of disagreement between the hypoosmotic swelling test and eosin in the samples with no postcryopreservation motility.

Cell Membrane↗
PubMed1998

Comparison of various methods of processing human cryopreserved-thawed semen samples.

We compared the efficacy of various methods of processing cryopreserved-thawed samples for the recovery of functionally adequate spermatozoa as assessed by the response to the sperm stress test (SST), an index of temperature activated sperm membrane lipid peroxidation, and immediate and delayed changes in sperm viability and motion parameters. Donor semen samples (n = 28) were cryopreserved-thawed and divided into six equal parts, one part was used as control and the remaining parts were used to compare five methods of sperm processing as follows: direct Percoll gradient processing, washing by one-step or stepwise addition of the washing medium followed by Percoll processing, and washing by one-step or stepwise addition of the washing medium. Additional samples (n = 10) were evaluated for the immediate and delayed (6 h at 37 degrees C) impact of one-step and stepwise washing (without Percoll separation). Compared with wash-only methods, samples processed using Percoll had a significantly higher SST score (P = 0.001), motility, rapid spermatozoa (>50 microm/s), curvilinear velocity and motility index (P < 0.001). Comparing various Percoll methods, direct Percoll processing resulted in the highest number of motile spermatozoa recovered (P < 0.00001) and a higher SST score based on curvilinear velocity (P = 0.001). Stepwise washing gave a significantly higher number of motile spermatozoa (P < 0.001) but with a significantly lower SST score based on the concentration of motile spermatozoa (P = 0.001), motility (P = 0.001) and motility index (P = 0.01). Sperm viability and motion parameters after 6 h of incubation showed no difference between one-step and stepwise washing. In conclusion, compared with wash-only methods, Percoll processed samples resulted in the recovery of spermatozoa with superior quality as assessed by SST and motion analysis. One-step washing of the samples gave an overall comparable recovery compared to the samples prepared stepwise. Having significantly higher SST scores, similar viability and the maintenance of motility, one-step washing may be a better method of processing thawed samples than the stepwise washing.

Cell Survival↗
PubMed1998

Concomitant fibrous dysplasia and aneurysmal bone cyst of the skull base. Case report and review of the literature.

The combination of fibrous dysplasia and aneurysmal bone cyst of the skull base is extremely rare yet it should be recognized, lest the rapid growth of the lesion and the radiological picture lead to the wrong diagnosis of a malignant process. We report on a 6(1/2)-year-old patient who suffered from concomitant fibrous dysplasia and aneurysmal bone cyst of the skull base. He is still disease-free 4 years postoperatively. The treatment of choice remains early surgical removal of the maximal amount of involved bone that can safely be achieved. There is no role for radiotherapy in the treatment of these lesions. A review of the literature is included.

Bone Cysts, Aneurysmal↗
PubMed1996

Characterization of Erwinia chrysanthemi by pectinolytic isozyme polymorphism and restriction fragment length polymorphism analysis of PCR-amplified fragments of pel genes.

Conserved regions about 420 bp long of the pelADE cluster specific to Erwinia chrysanthemi were amplified by PCR and used to differentiate 78 strains of E. chrysanthemi that were obtained from different hosts and geographical areas. No PCR products were obtained from DNA samples extracted from other pectinolytic and nonpectinolytic species and genera. The pel fragments amplified from the E. chrysanthemi strains studied were compared by performing a restriction fragment length polymorphism (RFLP) analysis. On the basis of similarity coefficients derived from the RFLP analysis, the strains were separated into 16 PCR RFLP patterns grouped in six clusters, These clusters appeared to be correlated with other infraspecific levels of E. chrysanthemi classification, such as pathovar and biovar, and occasionally with geographical origin. Moreover, the clusters correlated well with the polymorphism of pectate lyase and pectin methylesterase isoenzymes. While the pectin methylesterase profiles correlated with host monocot-dicot classification, the pectate lyase polymorphism might reflect the cell wall microdomains of the plants belonging to these classes.

Base Sequence↗