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Biomedical subjects

A Ammar

Publications and source records attributed to A Ammar.

At least 19 recordsLinked to original sources
PubMed2006

Radiation modifiers: treatment overview and future investigations.

Many radiosensitizers are in current clinical use. In addition, a myriad of potential new targeted therapies, which may also interact with radiation, are in clinical development. The clinical utility of new targeted therapies, in combination with existing radiation sensitizers (chemotherapies) requires further evaluation, as does the understanding of their acute and late radiation effects. Free radical scavengers appear to show promise as radioprotectors, but data for mucoprotection are less convincing.

Humans↗
PubMed2005

[Pleural effusion revealing multiple myeloma].

Pleural effusion is rarely observed in multiple myeloma, its frequence is estimated at 6%, and its myelomatous origin occurs in only 1% of the cases. It is exceptionally the first sign of multiple myeloma. We report two cases of IgA and IgG multiple myeloma revealed by pleural effusion. The first case was a 61-year-old woman who developed pleural effusion with a bone endobronchial and pericardial location of multiple myeloma; the second case was a 65-year-old man who had isolated pleural effusion. These pleural effusions were found to be caused by myeloma and were verified by the presence of the same monoclonal immunoglobulin in both plasma and pleural liquid. Atypical plasma cells were found in the pleural fluid.

Aged↗
PubMed2004

Investigation of the electronic and structural properties of potassium hexaboride, KB6, by transport, magnetic susceptibility, EPR, and NMR measurements, temperature-dependent crystal structure determination, and electronic band structure calculations.

The electronic and structural properties of potassium hexaboride, KB(6), were examined by transport, magnetic susceptibility, EPR, and NMR measurements, temperature-dependent crystal structure determination, and electronic band structure calculations. The valence bands of KB(6) are partially empty, but the electrical resistivity of KB(6) reveals that it is not a normal metal. The magnetic susceptibility as well as EPR and NMR measurements show the presence of localized electrons in KB(6). The EPR spectra of KB(6) have two peaks, a broad ( approximately 320 G) and a narrow (less than approximately 27 G) line width, and the temperature-dependence of the magnetic susceptibility of KB(6) exhibits a strong hysteresis below 70 K. The temperature-dependent crystal structure determination of KB(6) shows the occurrence of an unusual variation in the unit cell parameter hence supporting that the hysteresis of the magnetic susceptibility is a bulk phenomenon. The line width DeltaH(pp) of the broad EPR signal is independent of temperature and EPR frequency. This finding indicates that the line broadening results from the dipole-dipole interaction, and the spins responsible for the broad EPR peak has the average distance of approximately 1.0 nm. To explain these apparently puzzling properties, we examined a probable mechanism of electron localization in KB(6) and its implications.

Journal Article↗
PubMed2004

Neovascularization of the amniotic membrane as a biological immune barrier.

The clinical application of islet transplantation is limited due to the limited source and the morbidity of systemic immunosuppression to prevent rejection. The two problems can be solved by using encapsulated islets. We have used amniotic membranes as biocompatible natural immune barriers. The objective of this study was to assess the revascularization of the membrane, which is necessary to ensure islet viability when the membrane is used for islet encapsulation. The amniotic membranes, obtained from full-term pregnant female dogs, were molded to form macrocapsules, which were implanted in the peritoneal cavity. The capsules were removed after 3, 10, 15, and 30 days and examined histopathologically using hematoxylin and eosin and by immunohistochemistry for neovascularization using factor VIII to detect angiogenesis. Upon histopathological examination, all specimens showed localized, moderate inflammation and congested blood vessels with no thrombosis or rejection. There was a mild degree of fibroblast proliferation starting from day 10 to day 30. Immunohistochemical staining revealed that the number of blood vessels was 7, 11, 13, 10 per high-power microscopic field on days 3, 10, 15, and 30, respectively. We concluded from this study that implanted amniotic sac capsules were vascularized within the omental tissue from day 10 on with significant blood vessel formation starting on day 3 by immunohistochemical study.

Amnion↗
PubMed2003

Unusual hysteresis in the magnetic susceptibility of cubic hexaboride KB6.

Electrical resistivity, magnetic susceptibility, and electron paramagnetic resonance measurements were carried out for cubic hexaboride KB(6), which is one electron short of completely filling its conduction band. It is found that KB(6) is not metallic and has localized spins. KB(6) exhibits a highly unusual hysteresis in the magnetic susceptibility below 100 K, which suggests that it undergoes a slow relaxation process.

Journal Article↗
PubMed2003

[Costo-vertebral hydatid disease: the role of MRI].

INTRODUCTION: Hydatid disease of bone is very rare accounting for 0.5% - 3% of all localisations. CASE REPORT: We report the case of a woman of 30 years who presented with posterior chest pain. The chest radiograph showed an extra-pulmonary mass associated with a lytic rib lesion. Thoracic ultrasound revealed a multiloculated soft tissue and fluid mass. CT scan showed a fluid filled costo-vertebral cyst. MRI identified extension into the spinal canal. Pathological examination of the surgically resected material confirmed the diagnosis. CONCLUSIONS: This observation emphasises the role of MRI in assessing the extent of hydatid cysts of the posterior chest wall and in particular invasion of the spinal canal.

Adult↗
PubMed2002

[Metastatic benign leiomyoma in a 46-year-old woman].

Chest X-ray in a 46-year-old woman with a history of hysterectomy for a uterine mass revealed a nodular opacity measuring 3 cm. Computed tomography identified 3 other nodules. Histology examination of the lung lesions identified the same configuration as that of the hysterectomy specimen performed two years earlier: benign metastatic leiomyoma. Approximately 40 cases have been reported in the literature.

Diagnosis, Differential↗
PubMed2002

[Thymolipoma. A case report].

Thymolipoma is an uncommon benign tumor of the thymus. Asymptomatic, it is an incidental discovery. Pathogenesis remains controversial. We report a new case in a 36-year-old woman that was discovered on a chest x-ray ordered for pneumonia. The MRI findings suggested the diagnosis which was confirmed at the pathology examination of the surgical specimen.

Adult↗
PubMed2001

CSF hydrothorax--VP shunt complication without displacement of a peritoneal catheter.

Cerebrospinal fluid hydrothorax is reported as a rare complication of ventriculoperitoneal (VP) shunt. A 16-month-old boy known to have congenital hydrocephalus and a Dandy-Walker cyst presented with serious respiratory distress. Examination revealed right pleural effusion and congested throat. Thoracocentesis with drainage of the pleural cavity for 10 days failed to free the patient from pleural effusion. Following an intraperitoneal injection of Omnipaque a chest X-ray was done, and samples of pleural fluid taken before and after the injection were compared on X-ray, revealing the presence of contrast in the postinjection pleural effusion. Changing the VP shunt for a ventriculo-atrial shunt resulted in immediate (within 1 day) complete disappearance of the pleural effusion and of the patient's chest symptoms. Probable causes of this rare complication are discussed, and attention is drawn to the possibility of its appearance and early recognition. Intraperitoneal injection of contrast material followed by X-ray examination of fluid in the chest is a simple, safe, and reliable method of diagnosis when it is suspected.

Cerebrospinal Fluid↗
PubMed2001

[Muscle metastasis of a primary bronchial carcinoma].

Intra muscular metastasis are rare. They usually occurs during the course of a cancer. The primary bronchial carcinoma is the most common. Clinical features include painful mass, frequently, they are symptomatic. Sonography CT scan and MR imaging shows a non specific abnormally, but they defined their seat and their extension. The authors report a case of metastases of epidermoid bronchial carcinoma to left adductor muscle and gives a review of the literature.

Aged↗
PubMed2000

Spinal extradural angiolipoma.

We report a case of spinal angiolipoma, causing paraplegia in a 38-year-old pregnant female. The tumour was excised and the patient made remarkable recovery. The role of pregnancy and its associated hormonal profiles on tumour growth is discussed.

Adult↗
PubMed1999

Childhood intracranial arteriovenous malformation in Saudi Arabia.

Twenty-three patients in whom intracranial arteriovenous malformation (ICAVM) occurred while they were in the pediatric age group (16 years or less) were identified. The patients had presented to three major centers in Saudi Arabia (King Fahad Hospital of the University, King Faisal Specialist Hospital and Research Center, and Riyadh Military Hospital). The incidence of ICAVM in Saudi Arabia is estimated. ICAVM in the pediatric age group accounts for 7.72% of all ICAVM cases. Most of the pediatric patients presented with intracranial bleeding, and seizure was the only other mode of presentation. Spontaneous changes involving ICAVM occurred in 4 children, in the form of either increase or decrease in size or new vascularization. Most children had higher grade ICAVM and the morbidity rate was higher than in adults. The cure rate was 50% with different therapeutic modalities. This report represents the first study to provide the hospital-based frequency of pediatric ICAVM in Saudi Arabia.

Adolescent↗
PubMed1999

A young man has an idea. What should he do?

There is nothing more frustrating for a young neurosurgeon or neuroscientist than having an idea, and believing that it may work, and not knowing how to proceed. Even to the most persevering of people the process of converting the idea into reality is arduous and frustrating. A great deal of support is required in order to develop the idea and, unfortunately, the current basic medical education and post-graduate programs in most countries neither provide that support or, indeed, the knowledge of how to obtain it. Developing a creative ability is an art and science which needs to be developed through true experience requiring both time and patience. Many young researchers cannot tolerate the frustration and stumble at one of the numerous hurdles of lack of funding, sponsorship, proper guidance, lawyers, relationships with manufacturing companies, cost of registration of patent and insurance. Therefore, many great ideas are lost. It is essential to discover these young researchers and encourage them and provide them with all they need to mature their abilities. Ultimately the patient is the one who is going to gain the most from their inventions or discoveries. This very special need was one of the main concepts that led to the formation of the International Society of Neurosurgical Instrument Inventors, resulting in a forum whereby neurosurgeons with experience of inventing instruments can pool their experiences with young inexperienced neurosurgeons with fresh ideas. In this short paper some of the important obstacles facing any young neurosurgeon who may have a viable idea will be analyzed.

Equipment Design↗