Biomedical subjects
Publications and source records attributed to F Mohamed.
Long course bronchopneumonia in child imposes a bronchoscopy to research a foreign body. We report the case of a 4 years old child presenting an unusual foreign body overdraft at rigid tube bronchoscopy indicated for a training pneumonia. It was the membrane of burst pulmonary hydatic cyst obturing left bronchial tree. His total extraction permitted the complete recovery without retention of the membrane.
Fractured neck of femur is one of the most common reasons for hospital admission in the elderly population. Despite this little attention is given to the area of secondary prevention. To assess the variation in clinical practice among orthopaedic surgeons with regard to the use of secondary preventive measures in relation to fractured neck of femur. A postal survey using a self-completed questionnaire among all orthopaedic surgeons throughout the Republic of Ireland. The study questionnaire addressed unit information prophylaxis for deep venous thrombosis and investigation and secondary prevention of fractured neck of femur. It gave a clinical scenario of a 72-year old female who was admitted with a fractured neck of femur after a minor fall. A reminder was sent to the non-responders. Data were analysed using chi-squared test. The number of completed questionnaires returned was 89 giving a response rate of 66%. Of these 71(82.6%) reported that they would not initiate or recommend investigation of the extent of the underlying osteoporosis in the specific case upon which the questionnaire was based. With regard to the issue of secondary prevention 16(18%) stated that they would prescribe Vitamin D and 26(29%) would prescribe calcium supplements. 15(17%) would use bisphosphonates and 15(17%) would prescribe hormone replacement therapy. Only one respondent would use an external hip protector. There is an underuse of secondary preventive measures with regard to fractured neck of femur. There needs to be clear definition of roles and perhaps the development of agreed local protocols in order that patients with hip fractures do not miss out on potentially beneficial treatment. There is an underuse of secondary preventive measures with regard to fractured neck of femur. There needs to be clear definition of roles and perhaps the development of agreed local protocols in order that patients with hip fractures do not miss out on potentially beneficial treatment.
Dehydroleucodine (DhL), a sesquiterpene lactone (SQL) of the guaianolide type isolated from Artemisia douglasiana Besser, shows a pharmacological cytoprotective effect and significantly prevents the formation of gastric and duodenal lesions induced by various necrotising agents in rodents. The effects of DhL, on two models of experimental colitis were examined. Colitis was produced in male Wistar rats by rectal instillation of 5 and 10% acetic acid, following the methods of Eliakim et al. and Le Duc et al., respectively. In mice colitis was produced by rectal instillation of 0.1 ml of 2,4,6-trinitrobenzene sulphonic acid (5 mg in 50% ethanol) (TNB) as previously described by Chin et al. In this study, the administration of DhL 40 mg kg(-1)(1 h before the induction of colitis) significantly decreased mucosal damage. This effect was consistent in both models. The protection provided by DhL was accompanied by significant decreases in diarrhoea and colon weight; and histologically normal mucosa without ulceration and mucus production were observed. This study shows that both TNB and acetic acid colitis can be pharmacologically controlled by DhL. Our results suggest that the protective activity of DhL in experimental colitis is mediated, at least in part, through the increase of glycoprotein synthesis, anti-inflammatory effect and inhibition of COX-2 induction, and by inhibiting the degranulation of cells containing monoamines.
Magnetic resonance imaging is the method of choice for non-invasive detection and evaluation of tumors of the central nervous system. However, discrimination of tumor boundaries from normal tissue, and the evaluation of heterogeneous lesions have proven to be limitations in traditional magnetic resonance imaging. The use of post-image acquisition processing techniques, such as multispectral tissue segmentation analysis, may provide more accurate clinical information. In this report, we have employed an experimental animal model for brain tumors induced by glial cells transformed by the human neurotropic JC virus to examine the utility of multispectral tissue segmentation for tumor cell identification. Six individual tissue types were discriminated by segmentation analysis, including heterogeneous tumor tissue, a clear demarcation of the boundary between tumor and non-tumor tissue, deep and cortical gray matter, and cerebrospinal fluid. Furthermore, the segmentation analysis was confirmed by histopathological evaluation. The use of multispectral tissue segmentation analysis may optimize the non-invasive determination and volumetric analysis of CNS neoplasms, thus providing improved clinical evaluation of tumor growth and evaluation of the effectiveness of therapeutic treatments.
The neuroendocrine system regulates several organic functions such as reproduction, metabolism and adaptation to the environment. This system shows seasonal changes linked to the environment. The experimental model used in the present study was Lagostomus maximus maximus (viscacha). The reproduction of males of this species is photoperiod dependent. Twenty-four adult male viscachas were captured in their habitat at different times during one year. The adrenal glands were processed for light microscopy. Serial cuts were stained with hematoxylin-eosin for the morphometric study, and 100 nuclei of each zone of the adrenal cortex were counted per animal. Data were analyzed statistically by ANOVA and the Tukey test. The cells of the glomerulosa zone are arranged in a tube-shaped structure. The fasciculata zone has large cells with central nuclei and clearly visible nucleoli and with a vacuolar cytoplasm. In the reticularis zone there are two of types of cells, one with a nucleus of fine chromatin and a clearly visible nucleolus and the other with nuclear pycnosis. Morphometric analysis showed maximum nuclear volumes during the February-March period with values of 133 +/- 7.3 microm3 for the glomerulosa, 286.4 +/- 14.72 microm3 for the fasciculata, and 126.3 +/- 9.49 microm3 for the reticularis. Minimum nuclear volumes were observed in August with values of 88.24 +/- 9.9 microm3 for the glomerulosa, 163.7 +/- 7.78 microm3 for the fasciculata and 64.58 +/- 4.53 microm3 for the reticularis. The short winter photoperiod to which viscacha is subjected could inhibit the adrenal cortex through a melatonin increase which reduces the nuclear volume as well as the cellular activity.
Angiogenesis is a complex process that involves the activation of quiescent endothelial cells (ECs) to a proliferative and migratory phenotype and, subsequently, their redifferentiation to form vascular tubes. We hypothesized that NO contributes to angiogenesis by terminating the proliferative action of angiogenic growth factors and initiating a genetic program of EC differentiation. Human umbilical vein ECs (HUVECs) and calf pulmonary artery ECs (CPAECs) were grown directly on plastic dishes or on three-dimensional fibrin matrices. In the absence of fibrin, treatment with NO-donor compounds, such as S-nitroso-N-acetylpenicillamine (SNAP, 0.1 and 0.4 mmol/L), produced a dose-dependent inhibition of proliferation in both cell lines, whereas the inhibition of endogenous NO production using NG-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L) or NG-monomethyl-L-arginine (L-NMMA, 1 mmol/L) significantly increased proliferation of the CPAECs. The addition of basic fibroblast growth factor (bFGF, 30 ng/mL) increased the expression of endothelial NO synthase mRNA and the production of NO in both cell types when cultured on three-dimensional fibrin gels and produced profound morphological changes characterized by the appearance of extensive capillary-like vascular structures and the loss of EC monolayers. These changes were quantified by measuring total tube length per low-power field (x100), and a differentiation index was derived using the ratio of tube length over area covered by residual EC monolayer. In the absence of additional angiogenic factors, the differentiation index was low for both HUVECs and CPAECs (control, 1.16+/-0.19 and 2.07+/-0.87, respectively). Treatment with bFGF increased the differentiation index significantly in both cell types (10.59+/-2.03 and 20.02+/-5.01 for HUVECs and CPAECs, respectively; P<.05 versus control), and the addition of SNAP (0.4 mmol/L) mimicked the angiogenic response to bFGF (8.57+/-1.34 and 12.20+/-3.49 for HUVECs and CPAECs, respectively; P<.05 versus control). Moreover, L-NAME inhibited EC tube formation in response to bFGF in a dose-response manner, consistent with a role of endogenous NO production in EC differentiation in this angiogenic model. These findings suggest that NO may act as a crucial signal in the angiogenic response to bFGF, terminating the proliferative actions of angiogenic growth factors and promoting EC differentiation into vascular tubes.
Our aim was to develop an accurate multispectral tissue segmentation method based on 3D feature maps. We utilized proton density (PD), T2-weighted fast spin-echo (FSE), and T1-weighted spin-echo images as inputs for segmentation. Phantom constructs, cadaver brains, an animal brain tumor model and both normal human brains and those from patients with either multiple sclerosis (MS) or primary brain tumors were analyzed with this technique. Initially, misregistration, RF inhomogeneity and image noise problems were addressed. Next, a qualified observer identified samples representing the tissues of interest. Finally, k-nearest neighbor algorithm (k-NN) was utilized to create a stack of color-coded segmented images. The inclusion of T1 based images, as a third input, produced significant improvement in the delineation of tissues. In MS, our 3D technique was found to be far superior to that based on any combination of 2D feature maps (P < 0.001). We identified at least two distinctly different classes of lesions within the same MS plaque, representing different stages of the disease process. Further, we obtained the regional distribution of MS lesion burden and followed its changes over time. Neuropsychological aberrations were the clinical counterpart of the structural changes detected in segmentation. We could also delineate the margins of benign brain tumors. In malignant tumors, up to four abnormal tissues were identified: 1) a solid tumor core, 2) a cystic component, 3) edema in the white matter, and 4) areas of necrosis and hemorrhage. Subsequent neurosurgical exploration confirmed the distribution of tissues as predicted by this analysis.
Free protein S:Ag and protein S activity determined by clotting assay are often regarded as synonymous; however, in the study group of patients, abnormal protein S activity (PS:Act) results correlated poorly with abnormal free (PS:Ag(r2 = 0.164). Significantly none of the patients in whom lupus anticoagulant and low free protein S:Ag were detected were found to have low PS:Act. These results could not be explained by activated protein C resistance, suggesting that lupus anticoagulant may cause prolongation of the clotting time within the PS:Act assay and thus give falsely high results. As reduced levels of free protein S:Ag and/or protein S activity are considered risk factors of thrombosis in systemic lupus erythematosus, these findings question the suitability of the protein S activity assay for patients who may have phospholipid antibodies.
The constitutive expression of endothelial nitric oxide (NO) synthase (cNOS) is essential for the physiological regulation of vascular tone and structure. The mechanism of downregulation of steady state cNOS mRNA in human umbilical vein endothelial cells exposed to tumor necrosis factor-alpha (TNF-alpha) was investigated by using Northern blot analysis of total cellular RNA. TNF-alpha produced a dose- and time-dependent decrease in cNOS mRNA expression that was near maximal at 10 U/mL and 6 hours of exposure, respectively. In contrast, steady state expression of endothelin-1 and plasminogen activator inhibitor-1 (PAI-1) mRNA was upregulated by TNF-alpha. The pharmacological generation of NO using sodium nitroprusside (10 mumol/L) and S-nitroso-acetylpenicillamine (100 to 400 mumol/L) had no effect on cNOS mRNA levels, and TNF-alpha-induced downregulation of cNOS was not prevented by coincubation with the inhibitors of NO synthesis N omega-nitro-L-arginine methyl ester (1 mmol/L) and NG-monomethyl L-arginine (10 mmol/L). Under control conditions, cNOS and PAI-1 mRNA were stable after treatment with actinomycin D for periods greater than 24 hours, whereas endothelin-1 message was rapidly degraded (half-life, < 1 hour). Pretreatment with TNF-alpha (30 U/mL) selectively reduced that half-life of cNOS mRNA to less than 12 hours without altering the stability of PAI-1 message. TNF-alpha-induced destabilization of cNOS mRNA could be partially prevented by coincubation with cycloheximide (1 mumol/L) but was not reproduced by addition of sodium nitroprusside.(ABSTRACT TRUNCATED AT 250 WORDS)
Considering that the vizcacha (Lagostomus maximus maximus) is a very Lithium sensitive rodent, we planned a biochemical-histological study injecting IP doses of 1 mEq/kg/day LiCl during one month to adult vizcachas, and they were divided into three lots: Lot I the optical microscopy revealed evident renal, gonadal, hyphophyseal and adrenal damages; the biochemical analysis showed that Li significantly decreased the female serum LH levels while testosterone and estradiol levels were not affected. The male Li serum values resulted to be significantly higher than those of female animals. The damage was greater in male specimens. Lott II: the tissue recovery from the damage observed in Lot I was the following: total in hyphophysis, partial in testis, the same in kidney and was enhanced in adrenal and ovary. The Li renal clearance was determined in Lot III verifying no changes in both sexs. According to our results, Li (1 mEq/kg/day during one month) produce modifications in different tissues probably the gonadal damage may be consequence of a direct Li effect and not for a hyphophysis alteration, since in male vizcacha the LH serum level was not changed. In regard to the selective effect in the suprarenal glomerulus structure, this Li effect is produced via hyphophysis. In conclusion, the selective effect of Li on adrenal and gonada organs of this rodent is a contribution in order to warm about the possible reproduction of such effects in human beings.
The regulation of endothelin-1 (ET-1) production by endothelial cells is likely of crucial physiological importance in the maintenance of vascular homeostasis. The aim of the present study was to explore the possible role of cyclic nucleotides in the control of ET-1 production in human umbilical vein endothelial cells (HUVEC). ET-1 release was determined by measuring levels of immunoreactive ET-1 in HUVEC-conditioned media after 6-h incubations. In the presence of 10% fetal calf serum (FCS) there was a threefold increase in ET-1 release compared with serum-free conditions (1.96 +/- 0.17 vs. 0.56 +/- 0.06 pg/micrograms protein), respectively. Inhibition of protein kinase (PK) C using staurosporine (10 nM) reduced basal ET-1 release by approximately 50% and completely prevented the response to FCS. In contrast, the addition of other PK inhibitors had little effect on basal or serum-stimulated ET-1 release at the concentrations used. N6,2'-O-dibutyryladenosine 3',5'-cyclic monophosphate (DBcAMP) produced significant alterations in ET-1 release depending on the basal level of production. Under serum-free conditions of low basal ET-1 production, DBcAMP increased ET-1 release by 68 +/- 22% but only at the highest concentration studied (1 mM). The dose-response relationship for DBcAMP was potentiated by KT-5720 (0.1 microM), an inhibitor of PKA, with a significant shift to 10-fold lower concentrations, whereas it was blocked by KT-5823 (4 microM), which can inhibit PKG.(ABSTRACT TRUNCATED AT 250 WORDS)
Pulsation artifact on gradient echo images with ultrashort TE (i.e., < 3 msec) and intermediate TR is primarily from view-to-view amplitude modulation. Paramagnetic contrast agents increase the signal from blood during diastole without increasing the intensity of unsaturated systolic blood, decreasing signal modulation between systole and diastole. In a phantom and in humans, artifact decreased or remained the same following contrast enhancement.
The susceptibility of different species to bacteremia may influence the results of studies on vascular graft infection. The present study compares prosthetic graft infection in canine and porcine models. Thirty-four mongrel dogs and 38 Yorkshire pigs underwent replacement of the infrarenal aorta with a 3-cm segment of a woven Dacron prosthesis. At the time of closure, each animal received an intravenous inoculum of 10(2) to 10(8) Staphylococcus aureus (S. aureus). Graft cultures at 1 week produced a predictable infection rate in dogs, while pigs developed only random infections (dogs: 23/34; pigs: 7/38; p = .0001). The median infective dose (ID50) in dogs was 10(2.9) but pigs did not develop enough infections to determine this value. Electron microscopy revealed a smooth fibrin surface in grafts explanted from pigs, while grafts from dogs demonstrated bacteria enmeshed in an irregular fibrinous lining. Prosthetic vascular grafts in dogs are more susceptible to hematogenous infection than those in pigs. Because hematogenous infection in humans is a rare event, the swine model may be a more appropriate representation of the clinical situation.
Studies on vascular graft infections may be influenced by species differences in bacteria clearance. The present study compares the bloodstream elimination of Staphylococcus aureus (S. aureus) in dogs and pigs. Four mongrel dogs and four Yorkshire pigs received a 20-min infusion of 10(6) S. aureus labeled with indium-131. Through a catheter placed in the infrarenal aorta, blood samples were removed at intervals for 5 h after infusion. The liver, spleen, and lungs were biopsied at 5 h. Blood and tissue samples were then counted in a gamma counter. The calculated phagocytotic index, k, for dogs was 8.6 X 10(-4), while for pigs it was 1.5 X 10(-3), indicating significantly faster bacterial clearance in pigs (p = .009). After 2 1/2 h, significantly fewer counts were present in pigs at most time points (p less than .05). Organ counts indicated higher counts in the dog liver and spleen and in the lungs of pigs (p less than .0001). This study indicates that S. aureus bacteremia is cleared faster by pigs, primarily by the lungs, compared to dogs, in which liver-spleen clearance predominated. These differences should be considered when the results of graft infection studies are compared.
The sequence of acute ischemia, reperfusion, and elevated tissue pressure, with subsequent neuromuscular damage, results in the clinical entity known as the compartment syndrome. We have developed a canine hindlimb model that successfully replicates these clinical features. Surgical devascularization of both hindlimbs at the popliteal level isolates perfusion to a single vascular pedicle. Total ischemia is produced in the left limb for 8 h, while the right limb serves as a surgical control. Ischemia is confirmed by measurement of transfascial oxygen tension (TF-PO2) as well as lactate and blood gases in the venous effluent. Pressure in the anterior compartment of the hindlimb is monitored by the slit catheter technique. After reperfusion, muscle damage is assessed by histology, creatine phosphokinase (CPK), and uptake of technetium-99m pyrophosphate (Tc-PyP), expressed as a ratio of the experimental (L) limb to the control (R) limb (L/R ratio). Muscle necrosis was greatest in untreated controls; the L/R ratio was 8.9 +/- 5.0. Significant diminution of muscle necrosis was achieved by fasciotomy prior to reperfusion (2.6 +/- 0.8), mannitol (1.8 +/- 0.6), albumin-conjugated superoxide dismutase (SOD) 2.8 +/- 0.8), native SOD (2.3 +/- 1.0), fasciotomy combined with SOD (1.9 +/- 0.7), and continuous heparin (1.6 +/- 0.4) (p less than .01 vs controls). When fasciotomy was delayed until 2 h after reperfusion, there was no significant decrease in the L/R ratio (5.4 +/- 1.5; p = .15). Early fasciotomy following prolonged severe limb ischemia remains the treatment of choice, although these results suggest an emerging role for nonsurgical therapies as well. A summary of work done with this model as well as a review of other techniques is presented, along with a discussion of the pathophysiology of the compartment syndrome.
2 Egyptian goats and Boscat rabbits were experimentally inoculated with peste des petits ruminants (PPR) local Egyptian strain (PPR, Egypt 87). The inoculated animals contracted the disease with minor clinical manifestations, accompanied by rise of neutralizing antibodies to PPR virus. Virus was isolated from ocular and nasal secretions, buffy coat, spleen, and liver. No contact infection was observed between inoculated and healthy goats.
Because it is postulated that compartment syndrome developing secondary to an acute arterial occlusion may be due to reperfusion injury, oxygen-derived free radicals have been implicated in its genesis. To assess the possible beneficial effect of free radical scavengers in this setting, we used a previously established in vivo canine model of compartment syndrome to compare four groups: group I, no treatment; group II, prophylactic fasciotomy; group III, intravenous albumin conjugated superoxide dismutase (SOD); group IV, intravenous mannitol (hydroxyl radical scavenger). Both hind limbs were completely devascularized at the popliteal level except for an isolated pedicle to the anterior compartment. The right limb served as the nonischemic control, whereas the left underwent 8 hours of ischemia followed by reperfusion. Continuous monitoring of transfascial oxygen tension (tfPO2) demonstrated severe ischemia during occlusion (tfPO2 5.7 +/- 5.1 mm Hg) and restoration of blood flow with reperfusion (mean tfPO2 50 to 60 mm Hg). Measurements of compartment pressure were significantly higher after reperfusion in groups I, III, and IV when compared with those of group II (p less than 0.001, groups I and II; p less than 0.01, group IV). Extent of muscle necrosis assessed by technetium pyrophosphate scanning and expressed as a ratio of left to right legs was as follows: group I, 8.9 +/- 5.0; group II, 2.6 +/- 0.5; group III, 2.8 +/- 0.8; group IV, 1.8 +/- 0.6. Muscle contraction studies 16 hours after reperfusion indicated abnormal findings in all but group II. In conclusion, administration of free radical scavengers did not preserve normal neuromuscular function despite a significant reduction in muscle damage.(ABSTRACT TRUNCATED AT 250 WORDS)