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Biomedical subjects

A A Ismail

Publications and source records attributed to A A Ismail.

At least 19 recordsLinked to original sources
PubMed1996

FTIR study of the thermal denaturation of horseradish and cytochrome c peroxidases in D2O.

Fourier transform infrared (FTIR) spectroscopy was employed to examine the thermal denaturation of the Fe(III), Fe(II), and Fe(II)-CO forms of cytochrome c peroxidase and horseradish peroxidase in phosphate buffer at pD 7.0. The amide I' regions of the deconvolved spectra are consistent with predominantly alpha-helical secondary structure around room temperature, but the alpha-helical absorption of the two peroxidases differs significantly; bands assigned to alpha-helical components occur at 1659 and 1649 cm-1 in horseradish peroxidase and at 1652 and 1637 cm-1 in cytochrome c peroxidase. The thermal denaturation mechanisms of the peroxidases also vary. All three forms of cytochrome c peroxidase retain their secondary structure up to 50 degrees C, when bands characteristic of aggregation (1616 and 1684 cm-1) appear in the amide I' region, and above 55 degrees C rapid loss of secondary structure is accompanied by enhanced aggregation. In horseradish peroxidase, on the other hand, the Fe(III) and Fe(II) states exhibit dissimilar denaturation mechanisms. Slow, gradual alteration of secondary structure is observed for Fe(III) horseradish peroxidase on heating, and polypeptide unfolding appears to be complete around 90 degrees C, without aggregation. In Fe(II) and Fe(II)-CO horseradish peroxidase, aggregation bands appear at approximately 55 degrees C, signaling the onset of denaturation. Frequency shifts in the v(CO) bands above room temperature reveal the conformational changes in the heme cavity precede global conformational changes in cytochrome c peroxidase but not in horseradish peroxidase. The reduction in amide II intensities, due to peptide H-D exchange on heating the peroxidases in D2O, indicates the formation above room temperature of partially unfolded states with increased solvent accessibility but intact secondary structures.

Cytochrome-c Peroxidase↗
PubMed1995

Longitudinal study of the bone mineral content and of soft tissue composition after spinal cord section.

We present the results of a 1 year longitudinal study of bone mineral measurements and soft tissue composition in supra- and infra-lesional areas of 31 patients with a spinal cord injury (level D2-L3). Like others, we observed a rapid decrease of BMC in the paralysed areas, of approximately 4%/month during the first year in areas rich in trabecular bone and of approximately 2%/month in areas containing mainly compact bone. Lean soft tissue mass (muscle mass) decreases dramatically during the first months post injury in the legs, while fat content tends to increase. Though lean mass is better maintained in patients who develop spasticity, the evolution of BMC does not differ significantly between the groups of flaccid and spastic patients. In patients with partial or complete neurological recovery, a deficit in BMC of approximately 10% with regards to the initial value is still observed at 1 year in the lower limbs. The lean mass of the upper limbs increases early after the cord injury, because of intensive rehabilitation. No significant change in BMC was observed in the supra-lesional areas. These data confirm the rapid loss of bone in the paralysed areas of paraplegic patients, which occurs independently of the presence of spontaneous muscle activity or of passive verticalisation. In patients with recovery, BMC does not return to pre-injury values within 1 year. Thus, there would be an interest in preventing bone loss early in the course of the disease.

Absorptiometry, Photon↗
PubMed1995

"In vitro" effect of Egyptian tannin-containing plants and their extracts on the survival of pathogenic bacteria.

This study was conducted on leaves from tannin containing plants which are widely spread in Upper Egypt. From two plants also fruits were investigated (A. nilotica and A. farnesiana). One of the objectives was to determine the total soluble polyphenols and the soluble condensed tannins of these plants. Furthermore the assumed antimicrobial effect of A. nilotica and A. farnesiana leaves and their extracts on C. perfringens, E. coli and S. typhimurium was studied "in-vitro" at dilutions of 0.5% and 0.05%. The tests were carried out in physiological saline solution and in rumen fluid medium (RFM). The results revealed that the total soluble polyphenols ranged from 10.27% to 35.46% and the condensed tannins from 0.5% to 8.28% on dry matter base. The antimicrobial effect of the plant material was only observed on C. perfringens but not on E. coli and S. typhimurium. A. nilotica leaves destroyed the suspension of C. perfringens immediately after being added. Leaves from A. farnesiana showed a delayed affect. Plant extracts were less effective than the raw plant material. In RFM A. nilotica leaves destroyed the bacterial suspension after 10 minutes only at the concentration of 0.5%, but not at 0.05%. With A. farnesiana at a concentration of 0.5% only a reduction was observed. The concentration of 0.05% had no influence. The presence of other proteins than bacterial suspension in rumen fluid (rumen bacteria, protozoa and plant proteins) inhibits the antimicrobial effect of the plant material in a concentration of 0.05%, but not at 0.5%.(ABSTRACT TRUNCATED AT 250 WORDS)

Acacia↗
PubMed1993

Evaluation of calcium-antagonist (Nifedipine) in the treatment of pre-eclampsia.

The therapeutic effect of the calcium antagonist; Nifedipine was assessed in 30 patients with pre-eclampsia. Cases were randomly allocated into two groups; a study group (n = 20) who received Nifedipine capsules (20 mg every 8 h for 7 days) and a control group (n = 10) who received placebo capsules with the same regimen. After Nifedipine administration, there was a significant decrease in blood pressure, serum urea and creatinine and 24 h urinary proteins. No significant difference was found in FHR and S/D ratio of the umbilical artery between study and control groups or between initial values and after Nifedipine administration. Preliminary results indicated that Nifedipine decreased blood pressure and improved kidney functions without affecting the umbilical artery blood flow in cases of pre-eclampsia.

Adolescent↗
PubMed1992

Pressure-induced conformational changes in an antigen and an antibody and the implications on their use for hyperbaric immunoadsorption.

Pressure-induced conformational changes in two proteins, bovine serum albumin (BSA) and immunoglobulin G (IgG), were studied to assess the application of hyperbaric manipulation to the dissociation of antigen-antibody complexes. Antigen-antibody dissociation is important in the product-recovery phase of immunoadsorption, an affinity purification process. Three techniques were used in parallel for this study, including fluorescence, Fourier transform infrared (FTIR) spectroscopy, and the enzyme-linked immunosorbent assay (ELISA). Employing a fluorescent probe, fluorescent intensity measurements were used to detect protein conformational changes. FTIR spectroscopy was used to determine changes in protein secondary structure induced by high pressure, while the ELISA test was used to examine antibody recognition after the proteins had been pressure-treated. The results from this work demonstrate that IgG is resistant to conformational changes induced by pressures below 2 kbar. In contrast, BSA undergoes reversible conformational changes in this pressure range. However, these conformational changes are not reflected in tests measuring antibody recognition. These findings indicate that IgGs have the potential to be used as recycled ligands in immunoadsorption separation processes. Different antigens that are being considered for purification by immunoadsorption and separated by means of high pressure could be screened by the methods disclosed to determine their stability under high pressure conditions.

Adsorption↗
PubMed1992

Pregnancy-specific beta 1-glycoprotein (SP1) and its relation to fetal birth weight at term pregnancy.

The relation between serum levels of pregnancy-specific beta 1-glycoprotein (SP1) and actual fetal and placental weights was studied in 100 full-term pregnant women. This was compared with fetal weight determination by ultrasound. SP1 levels significantly correlated with fetal and placental weights. Its determination was found to be comparable to ultrasonography in placental fetal weight assessment, especially at the extremes of fetal weight (macrosomia and small for gestational age) where special obstetric management is warranted.

Adult↗
PubMed1992

Conformational and functional properties of peptides covering the intersubunit region of influenza virus hemagglutinin.

The functionally active part of influenza virus hemagglutinin was investigated through the synthesis of a series of peptides representing different parts of the intersubunit region. Secondary structure prediction, circular dichroism and Fourier transform infrared spectroscopic studies were undertaken to investigate the secondary structure of these peptides. The peptide fragments were found to adopt multiple conformations, depending on their concentration in solution, the presence of the non-ionic detergent octyl-beta-D-glucoside and the polarity of the solvent. The results of biological studies with these peptide fragments are discussed in relation to their conformation, as inferred from the spectroscopic analysis.

Amino Acid Sequence↗
PubMed1992

Aggregation of chymotrypsinogen: portrait by infrared spectroscopy.

Changes in the secondary structure and aggregation of chymotrypsinogen were investigated by infrared difference spectroscopy in conjunction with temperature and pressure tuning IR spectroscopy; both the amide I' band and side chain bands were studied. A prominent component of the amide I' band in the difference spectrum obtained upon cooling a chymotrypsinogen solution, or increasing the hydrostatic pressure, was observed in the region between 1627 and 1622 cm-1. Under denaturing conditions a white gel was formed, which is attributed to irreversible self-association or aggregation. This process was accompanied by the appearance of two new amide I' bands in the infrared spectrum of the protein: a very strong band at 1618 cm-1 and a weak band at 1685 cm-1. These bands are assigned to peptide segments with anti-parallel aligned beta-strands.

Chymotrypsinogen↗
PubMed1992

Salt bridge induced changes in the secondary structure of ionic polypeptides.

The carboxylate-containing homopolypeptides poly(L-glutamate) [poly(Glu)] and poly(L-aspartate) [poly(Asp)] were found to form different types of ordered structures in the presence of poly(L-lysine) [poly(Lys)]. Mixing poly(Glu) with poly(Lys) in aqueous solution at neutral pH results in the instantaneous formation of a gel-like precipitate. The secondary structure of the gel precipitate can be best described as intermolecular antiparallel beta-strands, involving the backbone amide groups, as evidenced by the presence of characteristic amide I bands in the ir spectrum at 1684 and 1612 cm-1. Mixing poly(Asp) with poly(Lys) under identical conditions results in the formation of a fine precipitate with a different morphology. Examination of the ir spectrum of the precipitate revealed that unlike poly(Glu), poly(Asp) did not yield any discrete secondary structure upon precipitation with poly(Lys). Addition of solutions containing Ca2+ or Mg2+ to the poly(Glu)/poly(Lys) aggregates resulted in complete dissolution of the gel, with the disappearance of the ir bands characteristic of the intermolecular hydrogen-bonded network. The results demonstrate the importance of salt bridges in establishing strong hydrogen bonds between the backbone amide groups. Reaggregation occurred upon heating the poly(Glu)/poly(Lys) mixture in the presence of Ca2+, but not in the presence of Mg2+ ions. In the presence of Ca2+ ions, aggregation and formation of an extended hydrogen-bonded network occurred upon heating. The aggregates formed upon heating poly(Glu)/poly(Lys) in the presence of Ca2+ were attributed solely to complexation of Ca2+ to the carboxylate groups of poly(Glu) with poly(Lys) remaining free in solution. Dissolution of the aggregate could be accomplished through addition of Mg2+ at room temperature.

Calcium↗
PubMed1992

Serum nickel, copper and zinc in Norplant users.

Changes in serum nickel, copper and zinc were evaluated in 45 Norplant users. Two groups were selected for this study. Group I included 15 regularly menstruating females as controls and as short-term users (90 days after Norplant insertion). Group II included 30 Norplant users for one year or more as long-term users. These elements were determined by atomic absorption spectrophotometry. Serum nickel showed no significant change in short-term nor in long-term users when compared to the control group or to each other. Serum copper and zinc revealed a significant increase in short-term users for a short period of time, which returned to normal levels in long-term users. There was disappearance of the cyclic changes in serum copper and zinc concentrations on comparing their levels in ovulatory to non-ovulatory Norplant users. The use of Norplant has no deleterious effects on serum levels of nickel, copper and zinc.

Adult↗
PubMed1992

Improving placental blood flow in pre-eclampsia with prostaglandin A1.

Prostaglandin A1 is a potent hypotensive, peripheral vasodilator, a weak oxytocic, antiplatelet aggregator. It improves the renal hemodynamics. Its effect on placental circulation was evaluated (expressed as systolic/diastolic ratio and umbilical artery resistance index) in 20 women with severe pre-eclampsia and 10 normotensive pregnant women, by using the Doppler technique. Moreover, another 10 women with severe pre-eclampsia received dextrose 5% as a placebo for comparative purposes. Significant improvements in both parameters studied were observed in the women with severe pre-eclampsia. The beneficial changes differed significantly from the recorded values when using dextrose in pre-eclampsia or prostaglandin A1 in normotensive subjects. Such promising data add another important perspective to prostaglandin A1 in severe pre-eclampsia and may open up new avenues for its use in other situations with compromised placental flow.

Adult↗
PubMed1991

Empty gestational sacs diagnosed by abdominal real-time ultrasonography.

310 patients with threatened abortion were examined by ultrasound. 86 cases showed empty gestational sacs of which 14 (16%) completed their pregnancy. All sacs were evaluated (and scored) with respect to size, shape, wall definition, trophoblastic reaction and position inside the uterus. Prediction of a non-viable pregnancy from a single ultrasound examination was achieved in some cases. However, this prediction could not be made in other cases before a follow-up ultrasound examination was performed. The proposed scoring system proved to be very helpful in identifying empty gestational sacs in which serial ultrasound examinations are highly required before termination of pregnancy.

Abortion, Spontaneous↗
PubMed1991

Elevated plasma adrenocorticotropin (ACTH) with adrenal hyperplasia: a new factor in ACTH regulation?

We report a patient with Cushing's syndrome in whom the etiology of the hypercortisolemia could not be definitely established despite extensive biochemical investigations. Results included raised basal serum cortisol, plasma ACTH, and urinary free cortisol; failure to suppress even a paradoxical rise in serum cortisol after dexamethasone (1 mg overnight, 2, 8, and 16 mg/day); and a definite but not exaggerated rise in 11-deoxycortisol after metyrapone. After iv CRF, plasma ACTH rose from 22 to 30 pmol/L. Abdominal computed tomographic scanning showed adrenal hyperplasia; the presence of an adrenal adenoma, although suspected, was not established. An unusual finding was the presence in the urine of large amounts of 21-deoxycortisol metabolites, including 3 alpha,11 beta,17 alpha-trihydroxy-5 beta-pregnan-20-one and 5 beta-pregnane 3 alpha,11 beta,17 alpha,20 alpha-tetrol. On the basis of preoperative biochemical/radiological findings, a provisional diagnosis of ACTH-dependent Cushing's syndrome associated with autonomous bilateral adrenal hyperplasia was made. Incomplete bilateral adrenalectomy was performed; adrenal hyperplasia was histologically confirmed, but no tumor was found. However, ACTH was measured 1) just before operation when the patient was receiving treatment with metyrapone, and 2) postoperatively when the patient was receiving steroid replacement only, and on these occasions ACTH levels were lower than during the initial investigations. Pituitary scans before and after adrenalectomy were similar, offering no evidence of pituitary infarction. We propose that abnormal production of 21-deoxycortisol contributed to the aberrant regulation of ACTH and cortisol in this case, providing an example of a previously unreported cause of hypercortisolemia.

Adrenal Glands↗
PubMed1990

Intrauterine administration of drugs for termination of pregnancy in the second trimester.

Medical methods have been used for many years to terminate mid-trimester pregnancy, ranging from irritant chemicals and traditional plants to ecbolic agents and solutions instilled locally into the uterus. These methods had serious limitations, with relatively high rates of maternal mortality and morbidity. Surgical evacuation requires special skills not available to all practitioners and many doctors consider second trimester dilatation and evacuation as a surgical taboo. In recent years several approaches evolved and reached the clinics, presenting safer and more effective options. Intra-amniotic instillation of hypertonic solutions, particularly saline or urea, proved in many hands to be a good method for pregnancies beyond 15 weeks of gestation. Due to a long latency period after instillation, these agents are often supplemented by an intravenous oxytocin infusion. Extraovular hypertonic saline or ethacridine (Rivanol) have their advocates, particularly in the grey-zone of pregnancy range from 13-15 weeks. In the last two decades, intrauterine prostaglandins were added to the methods in current use. Extra-amniotic prostaglandins (E2, F2 alpha or 15-methyl F2 alpha) were originally given in repeated doses or as a continuous local drip, but later a single instillation was used, usually mixing the drug with a viscous solution or gel. Intra-amniotic prostaglandins, in much higher doses, particularly the 15-methyl analogue, proved highly effective and relatively safe, especially when combined with laminaria tent insertion in the cervix. Various combinations of methods have provided a wide spectrum of data which is difficult to evaluate at present. Studies comparing different methods were mainly attempted in the mid-seventies. The outcome raised many pertinent questions and left many major issues unresolved. Most of the comparisons were not randomized or well-controlled and only referred to the natural prostaglandin compounds. The analogues, however, seem to offer several advantages and the role of additional methods such as laminaria or antiprogestins remains to be further evaluated.

Abortifacient Agents↗
PubMed1989

Changes in menstrual blood loss after four methods of female tubal sterilization.

One-hundred females requesting tubal sterilization were included in this study. They were enrolled into 4 groups, each n = 25. They were allocated to a particular method of sterilization on a randomized basis. The four modalities used were: laparoscopic Falope ring application, bipolar electrocoagulation, Hulka clip application and Pomeroy tubal ligation via minilaparotomy. The menstrual blood loss (MBL) was quantitatively estimated, using the alkaline hematin method, prior to sterilization and after 3, 6 and 12 months. No significant changes in MBL were observed after the four sterilization techniques. Moreover, they did not differ significantly in this context.

Adult↗
PubMed1989

Induction of labor by oral prostaglandin E2 in protracted pregnancy.

Induction of labor was performed in 20 pregnant females with postmaturity (greater than 294 days) using either oral PGE2 tablets (0.5 mg) or i.v. oxytocin drip (each group n = 10). The induction-establishment interval was significantly shorter in the oxytocin group (P less than 0.005). Moreover, the uterine activity (in Alexandria units) at 3 h post-induction and at the end of the first stage of labor, was significantly higher with i.v. oxytocin (P less than 0.005). However, the induction-delivery interval did not differ in both groups. All cases delivered spontaneously with a satisfactory Apgar score.

Administration, Oral↗
PubMed1989

Cervical prostaglandin injection: a novel method of administration for ripening the cervix and induction of labor.

Twenty pregnant women with greater than or equal to 36 weeks gestation and Bishop score of less than or equal to 4 were subjected to either intracervical injection of PGE2 (0.25 mg) every 4 h to ripen the cervix and induce labor (study group n = 10) or injection of only the diluent (control group n = 10). PGE2 cases showed significant increase in Bishop score and were successfully induced. The mean induction-establishment and induction-delivery intervals were 4.3 +/- 0.1 min and 6.07 +/- 1.7 h, respectively. The control group showed no response. PGE2 cervical injection is a safe and effective method for cervical ripening and labor induction.

Adult↗