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Biomedical subjects

M Ahmed

Publications and source records attributed to M Ahmed.

At least 145 records · Page 8Linked to original sources
PubMed1998

Neurosurgical aspects of sphenoid sinus mucocele.

The aetiological spectrum of sphenoid sinus mucocele includes congenital anomaly, trauma, infection, allergy and surgery of the sphenoid sinus. Enlargement of the mucocele, even with a short history, can result in progressive expansion of the sinus and extension of the lesion into the pituitary fossa, the suprasellar region, nasopharynx, orbits, clivus or ethmoid air cells. It is a benign cystic lesion with an excellent prognosis when treated appropriately. Generally, these lesions are managed by an ear, nose and throat surgeon, but when there is extension into the sellar and parasellar (especially suprasellar) regions they are managed by the neurological surgeon. Sphenoid sinus mucocele should be considered in the differential diagnosis when there is suspicion of a cystic lesion in these regions. Three cases of large sphenoid sinus mucocele are presented, with discussion on their neurosurgical management and a review of the literature.

Adult↗
PubMed1998

Spontaneous rupture of infantile umbilical hernia: report of three cases.

Three Nigerian infants with spontaneous rupture of an umbilical hernia are described. In two, hernias developed in the neonatal period following umbilical sepsis. Rupture occurred at the ages of 2 and 3 months, respectively, and was probably precipitated by raised intra-abdominal pressure resulting from excessive crying. The third child had a large, ulcerated umbilical hernia which ruptured at 10 months and was precipitated by damage to the overlying skin. The children were treated successfully.

Anti-Bacterial Agents↗
PubMed1998

Sphenoid sinus brown tumor of secondary hyperparathyroidism: case report.

OBJECTIVE AND IMPORTANCE: Brown tumor is a misnomer for a reparative cellular process caused by primary or, less commonly, secondary or tertiary hyperparathyroidism. Atypical involvement of the base of the cranium in the area of the sphenoid sinus and the orbit is exceedingly rare and may produce a neurological deficit as a primary clinical presentation. Those neurosurgeons dealing with cranial base and pituitary lesions should be aware of this disease entity, and it should be listed in the differential diagnosis. CLINICAL PRESENTATION: A 21-year-old woman with end-stage renal failure on chronic dialysis was referred to the Department of Neurosciences at King Faisal Specialist Hospital and Research Centre with a 4-month history of progressive impairment of vision, associated with headache and nausea. Computed tomography and magnetic resonance imaging demonstrated an expansive mass lesion in the sphenoid sinus with erosion of the sellar floor and posterior medial wall of the orbit causing compression of the optic nerves. The biochemical laboratory studies showed elevation of parathyroid hormone and confirmed the diagnosis of hyperparathyroidism. INTERVENTION: The transnasal-transsphenoidal approach was used for extensive microsurgical removal of the lesion. The postoperative course was uneventful, and the improvement in vision was dramatic. CONCLUSION: Brown tumor, although rare, should be listed in the differential diagnosis of expansive mass lesions in the area of the sphenoid sinus and cranial base. The management is multidisciplinary, and therapeutic options should target the underlying cause.

Adult↗
PubMed1998

Effect of vesicular stomatitis virus matrix protein on transcription directed by host RNA polymerases I, II, and III.

The matrix (M) protein of vesicular stomatitis virus (VSV) functions in virus assembly and inhibits host-directed gene expression independently of other viral components. Experiments in this study were carried out to determine the ability of M protein to inhibit transcription directed by each of the three host RNA polymerases (RNA polymerase I [RNAPI], RNAPII, and RNAPIII). The effects of wild-type (wt) VSV, v6 (a VSV mutant isolated from persistently infected cells), and tsO82 viruses on poly(A)+ and poly(A)- RNA synthesis were measured by incorporation of [3H]uridine. v6 and tsO82 viruses, which contain M-gene mutations, had a decreased ability to inhibit synthesis of both poly(A)+ and poly(A)- RNA. Nuclear runoff analysis showed that VSV inhibited transcription of 18S rRNA and alpha-tubulin genes, which was dependent on RNAPI and RNAPII, respectively, but infection with wt virus enhanced transcription of 5S rRNA by RNAPIII. The effect of M protein alone on transcription by RNAPI-, RNAPII-, and RNAPIII-dependent promoters was measured by cotransfection assays. M protein inhibited transcription from RNAPI- and RNAPII-dependent promoters in the absence of other viral gene products. RNAPIII-dependent transcription of the adenovirus VA promoters was also inhibited by M protein. However, as observed during wt VSV infection, M protein enhanced endogenous 5S rRNA transcription, indicating that the inhibition of transcription by RNAPIII was dependent on the nature of the promoter.

Animals↗
PubMed1998

Persistent systemic inflammatory response after stent insertion in patients with malignant bile duct obstruction.

BACKGROUND: Surgery in patients with malignant bile duct obstruction is associated with high postoperative morbidity and mortality. Tumour necrosis factor alpha (TNF-alpha) plays a key role in the pathogenesis of these complications. AIMS: To determine the effect of biliary drainage on plasma concentrations of TNF-alpha, its soluble circulating receptors (sTNFr), and other proinflammatory cytokines. METHODS: Plasma concentrations of TNF-alpha, sTNFr-P75, interleukin 6 (IL-6), and IL-1 alpha were measured in 25 patients with malignant bile duct obstruction before and after endoscopic stent insertion. RESULTS: Mean serum bilirubin was 157 mumol/l before stent insertion and 35.2 mumol/l one week post stent insertion. There was complete relief of jaundice in 77% of patients by four weeks. Plasma concentrations of TNF-alpha and IL-1 alpha were below the detection limit of the assays in all samples. Median plasma sTNFr-P75 in the cancer patients was 960 ng/l (range 400-6600), before stent insertion and remained unchanged at one and four weeks after stenting. Plasma sTNFr-P75 in cancer patients was significantly higher (p < 0.01) than in healthy controls (250 (200-650) ng/l). Before stent insertion, plasma IL-6 concentrations were detectable (above 5 ng/l) in 17 (68%) patients. After relief of biliary obstruction IL-6 levels fell from a prestent median of 13.2 to less than 5 ng/l at one week after stent insertion. Plasma concentrations of IL-6 were undetectable in 76% of patients at this time. CONCLUSION: Activation of the TNF/sTNFr complex is unchanged after biliary drainage in patients with malignant bile duct obstruction. This may explain why preoperative drainage does not influence the high morbidity and mortality associated with surgery in these patients.

Cholestasis↗
PubMed1998

Sensory nerves in the interface membrane of aseptic loose hip prostheses.

We studied the presence of sensory nerves by immunohistochemistry in the interface membranes of hip prostheses after aseptic loosening. Substance P (SP), neurokinin A (NKA) and calcitonin gene-related peptide (CGRP) were analysed as was protein gene product (PGP) 9.5, a general marker for nerve fibres. We identified nerve fibres in all samples but differences in their density were found. SP- and NKA-positive fibres were predominantly non-vascular, forming varicose nerve terminals. CGRP-immunoreactive nerve fibres with varicose terminals were seen mostly close to blood vessels, but also as free nerve endings. Sensory neuropeptides participate not only in nociception but also stimulate immune cells to release cytokines. The presence of sensory nerves in the interface membrane may reflect a pathophysiological response contributing to the aseptic loosening of hip prostheses.

Aged↗
PubMed1998

The role of colour Doppler imaging in the management of Peyronie's disease.

OBJECTIVE: To determine the role of colour Doppler imaging (CDI) in the investigation of erectile dysfunction in patients with Peyronie's disease. PATIENTS AND METHODS: Fifty consecutive patients (age 35-75 years) with Peyronie's disease who were considered suitable for surgical treatment were investigated using CDI to determine the haemodynamic variables of penile vasculature after an intracorporeal injection of 20 microg of alprostadil (with manual self-stimulation). A clinician independently recorded the quality of erection and the deformity. RESULTS: Twenty of 50 patients (40%) considered they had normal erectile function despite their penile deformity and all had normal responses, although they tended to exaggerate the degree of penile deformity. Of the 30 remaining patients, 21 who considered themselves to have erectile dysfunction had normal clinical and CDI haemodynamic responses to alprostadil. The remaining nine patients had a variety of erectile problems and whilst CDI showed altered haemodynamic values, in no case did CDI alter the proposed treatment based on the clinically apparent features of those patients. CONCLUSION: Colour Doppler imaging of the penis after pharmacologically induced erection gives anatomical and functional information in patients with Peyronie's disease but does not provide useful additional information to aid the selection of surgical treatment for the disease.

Adult↗
PubMed1998

Hypomagnesaemia in postoperative patients: an important contributing factor in postoperative mortality.

Magnesium is the second most abundant intracellular cation and the fourth most abundant cation in the body. Clinical manifestations of hypomagnesaemia include neuromusclar, neurological, psychiatric and cardiac arrhythmias including torsade de pointes resulting in sudden death. Incidence of hypomagnesaemia in hospitalised patients in common and there is a lack of clinical awareness. Clinicians should become familiar with the common conditions and therapeutics that are risk factors for underlying hypomagnesaemia and become familiar with magnesium replacement regimens. Two patients who suffered fatal complications in whom hypomagnesaemia was an important contributing factor are presented. Hypokalaemia and hypocalcaemia are common in severe magnesium deficiency and require concurrent monitoring and correcting.

Adult↗
PubMed1998

Pattern of tuberculosis in general practice.

An audit of 690 cases of tuberculosis out of 46,276 patients seen during the last 25 years in a busy general practice is reported. Of the 690 cases, 67% were pulmonary, 33% extra-pulmonary TB. Modes of both types of tuberculosis are described and the reason for increased incidence of extra-pulmonary tuberculosis are discussed.

Adolescent↗
PubMed1997

Identification of a consensus mutation in M protein of vesicular stomatitis virus from persistently infected cells that affects inhibition of host-directed gene expression.

In addition to its function in virus assembly, the viral matrix (M) protein of vesicular stomatitis virus (VSV) inhibits host-directed gene expression. The goal of this study was to determine whether sequence changes in M protein contribute to a reduced shut off of host gene expression in cells persistently infected with VSV. Viruses isolated from L cells persistently infected with VSV inhibited host RNA synthesis more slowly than wild-type (wt) VSV. M genes of the persistent viral population were cloned and sequenced. One mutation, an N to D change at position 163 of the protein sequence (N163D), was common to all the molecular clones. The N163D M protein was synthesized from transfected mRNA at a rate that was 30% of that of wt M protein, but was turned over at a rate that was similar to that of wt M protein. Transfection of mRNA encoding N163D M protein inhibited expression of a cotransfected target gene encoding chloramphenicol acetyl transferase (CAT), but the inhibition was 6 to 10 times less effective than transfection of equivalent amounts of wt M mRNA. This difference could not be accounted for by differences in translation of CAT mRNA. Thus, when the differences in M protein expression were taken into account, N163D M protein was 2 to 3 times less effective than wt M protein in the inhibition of host-directed gene expression, similar to the differences in host transcription observed in virus-infected cells. Point mutations in addition to the N163D mutation were found in about half of the M gene molecular clones. The M gene of an independently isolated molecular clone, N163D.2, contained two additional point mutations in its carboxy terminal region. N163D.2 M protein was highly defective in inhibition of host gene expression and was turned over more rapidly than wt M protein. These results support the idea that M gene mutations contribute to a reduced cytopathic effect in cells persistently infected with VSV.

Cell Line↗
PubMed1997

Expression of corticotropin-releasing factor in the peripheral nervous system of the rat.

The occurrence and distribution of corticotropin-releasing factor (CRF) in the rat peripheral nervous system was studied by immunohistochemistry. CRF-positive nerve fibers were identified in the spleen, thymus, synovial membrane of the knee joint and adrenal gland. In general, CRF-positive fibers were seen predominantly in and around the blood vessels; however, many non-vascular thin varicose fibers were also observed. The neuronal character of the immunoreactive fibers was confirmed by staining consecutive tissue sections with a general neuronal marker, protein gene product 9.5. The finding of CRF-positive nerve fibers in the periphery demonstrates a strong anatomical link between the nervous, endocrine and immune systems, and may have pathophysiological implications in the inflammatory and stress-related disorders.

Animals↗
PubMed1997

Preconditioning of human myocardium with adenosine during coronary angioplasty.

BACKGROUND: It is unknown whether adenosine can precondition human myocardium against ischemia in vivo. METHODS AND RESULTS: Thirty patients were randomized to receive a 10-minute intracoronary infusion of adenosine (2 mg/min) or normal saline; 10 minutes later, they underwent percutaneous transluminal coronary angioplasty (PTCA; three 2-minute balloon inflations 5 minutes apart). In control patients, the ST-segment shift on the intracoronary ECG was significantly greater during the first inflation than during the second and third inflations, consistent with ischemic preconditioning. In contrast, in adenosine-treated patients, there were no differences in ST-segment shift during the three inflations. The ST-segment shift was significantly smaller in the adenosine-treated group compared with the control group during all three inflations. The reduction in ST-segment shift afforded by adenosine during the first inflation (-72% versus first inflation in control subjects) was greater than that afforded by ischemic preconditioning in control subjects (-52% during the third versus first inflation). Measurements of chest pain score paralleled those of ST-segment shift. Adenosine had no effect on baseline regional wall motion as determined by quantitative two-dimensional echocardiography. Thus, intracoronary infusion of adenosine before PTCA rendered the myocardium remarkably resistant to subsequent ischemia. Judging from the intracoronary ECG, the protection provided by adenosine was even superior to that provided in control subjects by the ischemia associated with the first two balloon inflations. Infusion of adenosine had no major adverse effects in patients undergoing PTCA of the left anterior descending or circumflex arteries. CONCLUSIONS: Adenosine preconditions human myocardium against ischemia in vivo. Pretreatment with adenosine is remarkably effective (even more effective than ischemic preconditioning) and could be used prophylactically to attenuate ischemia in selected patients undergoing PTCA of the left anterior descending coronary artery. Whether adenosine can be safely infused into the right or the circumflex coronary artery in the presence of a temporary pacemaker remains to be established.

Adenosine↗
PubMed1997

Benign polyps with prostatic-type epithelium of the urethra and the urinary bladder.

The clinico-pathological features of nine urethral and urinary bladder polyps with prostate-type epithelium are described. The average age of the patients was 46 years. Three patients previously had cystoscopy and the lesion was not noticed on the initial examination. The commonest presentation in this series was haematuria, dysuria and frequency of micturition. One patient presented with postmicturition dribble and another with haemospermia. The polyps contained acini and papillae lined by prostate-type epithelium which was confirmed by immunohistochemical tests for prostate specific antigen and prostate acid phosphatase. In this series no age versus location relationship could be established. Symptoms resolved following resection or initial biopsy followed by fulguration. Recurrence is extremely rare.

Acid Phosphatase↗
PubMed1997

Plasma clearance of cholyl-lysyl-fluorescein: a pilot study in humans.

BACKGROUND/AIMS: Cholyl-lysyl-fluorescein is a fluorescent analogue of the natural bile acid, cholyl glycine. In vivo and in vitro studies showed that this analogue has many biological characteristics similar to cholyl glycine. In this study we analysed cholyl-lysyl-fluorescein plasma clearance in six healthy volunteers as a potential quantitative liver function test. METHODS: The compound in water for injection was administered as an i.v. bolus in the dose of 0.02 mg/kg b.w. RESULTS: The plasma elimination curve showed rapid, intermediate and slow phases of clearance. Half-life (T1/2 time) for the first (t1/2 1st phase), second (t1/2 2nd phase) and third (t1/2 3rd phase) phases of elimination was 1.7+/-0.9 min, 6.7+/-1.6 min and 68+/-17 min, respectively. Ninety-minute plasma retention (% dose/l plasma) was 2.2%. Cholyl-lysyl-fluorescein volume of distribution and residual fluorescence after 60 min were similar to the data obtained by others for natural or radiolabelled bile acids. In five out of six healthy volunteers a 25-fold higher dose of cholyl-lysyl-fluorescein (0.5 mg/kg b.w.) was injected to estimate the safety margins of the compound. This dose was eliminated at a disappearance rate similar to that of the dose of 0.02 mg/kg b.w. and did not cause any adverse reactions. Serum liver tests measured before and after injection did not change significantly. CONCLUSIONS: This study showed that cholyl-lysyl-fluorescein clearance is similar to the clearance of endogenous natural bile acids and may potentially offer a new, dynamic test of liver function.

Adult↗
PubMed1997

Transurethral microwave thermotherapy (Prostatron version 2.5) compared with transurethral resection of the prostate for the treatment of benign prostatic hyperplasia: a randomized, controlled, parallel study.

OBJECTIVE: To compare transurethral microwave thermotherapy (TUMT) with urethral cooling in a high-energy protocol (Prostatron version 2.5), with transurethral resection of the prostate (TURP) for the treatment of symptomatic, uncomplicated, urodynamically obstructive benign prostatic hyperplasia (BPH). PATIENTS AND METHODS: Patients with moderate to severe symptomatic, uncomplicated BPH, unequivocally obstructed as assessed from the Abrams-Griffith nomogram, who were technically suitable for either form of treatment, were randomized into two groups of 30 patients each to undergo either TUMT or TURP. Five efficacy variables, i.e. the American Urological Association (AUA) symptom score, maximum flow rate (Qmax), post-void residual urine volume (PVR), voiding pressure at maximal flow (Pdet max) and prostatic volume determined by ultrasonography (PV) were measured initially and 6 months after treatment using a defined protocol. Complications were recorded during and up to 6 months after the treatment. As the variables were independent, the data were analysed using a paired t-test for each to assess the treatment effect for each group. RESULTS: After TURP, all the variables improved significantly; after TUMT, the symptoms improved both clinically and statistically (P < 0.001), with the mean AUA symptom score decreasing from 18.4 to 5.2. However, none of the objective variables improved after TUMT. The energy delivered under software control correlated poorly with prostatic volume (r = 0.322). TUMT had considerably lower morbidity than TURP, but failure of ejaculation occurred in four of 18 sexually active men after TUMT. CONCLUSIONS: Despite considerable improvement in their symptoms, TUMT using the Prostatron and Prostasoft v2.5 did not alleviate obstruction in patients with BPH. Patients treated using TUMT controlled by this software should be informed of the possibility of ejaculatory dysfunction.

Aged↗