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Biomedical subjects

A Ali

Publications and source records attributed to A Ali.

At least 73 records · Page 4Linked to original sources
PubMed2001

Hypodontia, ankylosis and infraocclusion: report of a case restored with a fibre-reinforced ceromeric bridge.

Retained primary molars without permanent successors often undergo progressive infra-occlusion, without predictable exfoliation. Early prophylactic removal, after assessment of root resorption and adjacent periodontal support loss as well as age of onset, is often indicated. This article describes the joint orthodontic-restorative care of such a case and describes an alternative method of restoration using a fibre-reinforced ceromeric bridge. As well as a conservative preparation and good aesthetics, an overlay restoration provided a fully functional occlusion.

Anodontia↗
PubMed2001

A canine model of gastroesophageal reflux disease (GERD).

BACKGROUND: Although a variety of antireflux procedures and medications are used to treat gastroesophageal reflux disease (GERD), reliable large-animal models of GERD that can be used to objectively compare the efficacy of these treatments are lacking. METHODS: Esophageal manometry and 24-h gastroesophageal pH monitoring with event data were performed in 18 mongrel dogs with a cervical esophagopexy. We then calculated a modified DeMeester score: The Duke Canine reflux score (DCR). Thereafter, the animals underwent a 4-cm anterior distal esophageal myotomy, incision of the left diaphragmatic crus, and intrathoracic gastric cardiopexy. Postoperative 24-h pH and manometry were obtained 2 weeks later. RESULTS: The postoperative 24-h pH results showed a significant increase in the mean DCR score (5.9 +/- 4.5 vs 84.9 +/- 56.1, p < 0.0002), and manometry indicated a significant decrease in mean lower esophageal sphincter (LES) pressure (7.1 +/- 2.9 vs 3.2 +/- 2.5 mmHg, p < 0.0001). CONCLUSION: This technique reliably creates a canine model of GERD.

Animals↗
PubMed2001

Histologic evaluation of fetal brains following maternal pneumoperitoneum.

BACKGROUND: The purpose of this study was to determine if maternal pneumoperitoneum with carbon dioxide (CO2) produces evidence of central nervous system (CNS) injury in preterm fetal guinea pigs. METHODS: Thirty pregnant guinea pigs at gestational day (GD) 45 were assigned at random to one of three treatment groups: anesthesia only, CO2 pneumoperitoneum (5 mmHg), or laparotomy. Dams were killed 3 or 5 days postprocedure and fetal brains (83 total) harvested and fixed for subsequent histopathologic evaluation. For comparative purposes, histologic features of fetal guinea pig brain injury were defined from examination of fetal brains harvested from an additional dam that underwent laparotomy with 20 min of uterine arterial occlusion. RESULTS: Carbon dioxide pneumoperitoneum did not increase maternal/fetal morbidity. No evidence of brain injury was found in fetuses from any of the treatment groups. CONCLUSION: Carbon dioxide pneumoperitoneum at 5 mmHg for 40 min in the pregnant guinea pig does not produce evidence of fetal brain injury.

Animals↗
PubMed2001

Morphological and functional characteristics of the dominant follicle and corpus luteum in cattle and their influence on ovarian function.

Predicting the functional activity of a dominant follicle (DF) and corpus luteum (CL) might be important before starting a superovulation regime or a synchronization program. The DF and CL were characterized morphologically by using ultrasonography and were characterized functionally by estimating the estradiol-17beta/progesterone (E2/P4) ratio. Their influence on ovarian function was estimated through their ability to ovulate at different stages of development in response to PGF2alpha-application. A total of 47 Holstein Friesian (35 cows and 12 heifers) were used in two experiments. In Experiment 1, 25 animals were examined by daily transrectal palpation and ultrasonography to follow the morphological development of the DF. The status of the DF was categorized into 3 groups (A1, B1, C1). The A1 group (n=7) contained animals with DF in the growing phase or in early static growth phase for less than 3 days. Group B1 (n=13) included animals with DF in static growth phase for 3 to 4 days, while Group C1 (n=5) comprised animals with DF keeping a plateau for more than 4 days or animals with DF in the regression phase. The DF were aspirated transvaginally and the follicular fluid (FF) was analyzed for E2 and P4. In Experiment 2, 22 animals were included. As in Experiment 1, the animals were classified into three groups (A2, n=10; B2, n=5; C2, n=7). They were treated by a single dose of PGF2alpha (25 mg, i.m.) between Days 8 and 12 of the cycle. Results showed that luteolyses occurred in all animals. The DF, which were in growing or in early static growth phase < 3 days were always E2-dominant (E2 > P4) and ovulated after PGF2alpha-application in 6/8 of cases and persisted in 2 (Group A2). The DF persisting > 4 days or that had been in regression were always P4-dominant. This type of DF regressed after PGF2alpha-application (Group C2). The DF in early static growth phase for 3 to 4 days in 5/13 cases were E2-dominant and in 8/13 cases were P4-dominant. This type of DF ovulated in 3/5 cases and regressed in 2/5 cases after PGF2alpha-application (Group B2). These results suggest that the DF is morphologically and functionally defined as long as the DF is in the growing or early static growth phase (A1, A2) for at least 2 days or if the DF is in regression (C1, C2). However, when the DF is in the static growth phase for 3 or 4 days (B1, B2), their morphological and functional characteristics are different. The CL controlls ovulation in the A and C groups and plays an abettor's roll in the B-group.

Animals↗
PubMed2001

ATR/ATM-mediated phosphorylation of human Rad17 is required for genotoxic stress responses.

Genotoxic stress triggers the activation of checkpoints that delay cell-cycle progression to allow for DNA repair. Studies in fission yeast implicate members of the Rad family of checkpoint proteins, which includes Rad17, Rad1, Rad9 and Hus1, as key early-response elements during the activation of both the DNA damage and replication checkpoints. Here we demonstrate a direct regulatory linkage between the human Rad17 homologue (hRad17) and the checkpoint kinases, ATM and ATR. Treatment of human cells with genotoxic agents induced ATM/ATR-dependent phosphorylation of hRad17 at Ser 635 and Ser 645. Overexpression of a hRad17 mutant (hRad17AA) bearing Ala substitutions at both phosphorylation sites abrogated the DNA-damage-induced G2 checkpoint, and sensitized human fibroblasts to genotoxic stress. In contrast to wild-type hRad17, the hRad17AA mutant showed no ionizing-radiation-inducible association with hRad1, a component of the hRad1-hRad9-hHus1 checkpoint complex. These findings demonstrate that ATR/ATM-dependent phosphorylation of hRad17 is a critical early event during checkpoint signalling in DNA-damaged cells.

Animals↗
PubMed2001

Mechanisms of acquired thymic tolerance: induction of transplant tolerance by adoptive transfer of in vivo allomhc peptide activated syngeneic T cells.

BACKGROUND: Our most recent observation that i.v. injection of Wistar-Furth (WF) major histocompatibility complex Class I peptide 5 (P5)-pulsed self-myeloid or lymphoid dendritic cells (DC) induces transplantation tolerance suggests that adoptive transfer of in vivo allopeptide-primed host T cells might induce acquired tolerance through their interaction with thymic DC. METHODS: To examine this hypothesis, host myeloid DC cultured in rat granulocyte/macrophage colony stimulating factor and interleukin 4 were pulsed in vitro with P5 and injected intravenously into syngeneic ACI rats. The T cells primed to P5 via the indirect pathway of allorecognition were harvested 7 days later and administered by either intravenously or intrathymically into syngeneic ACI recipients of WF cardiac allografts. RESULTS: Syngeneic T cells obtained from the spleen of P5-primed rats had a high mixed lymphocyte reaction proliferative response to P5 presented by self-DC. I.v. administration of 2x107 P5-primed alloreactive purified host splenic T cells alone on day -7 significantly (P<0.001) prolonged cardiac allograft survival from 10.5+/-1.0 days to 18.6+/-1.8 days in the WF-to-ACI rat combination. I.v. injection of P5-activated host T cells combined with 0.5 ml antilymphocyte serum (ALS)-transient immunosuppression on day -7 led to 100% donor-specific permanent graft survival (>200 days). Thymectomy before i.v. injection of P5-activated syngeneic T cells led to acute graft rejection, suggesting that the homing of in vivo activated T cells to the host thymus might play a role in the induction of tolerance. To further define the role of the recipient thymus in this model, we examined the effects of intrathymic (i.t.) injection of P5-primed alloreactive T cells on graft survival and found that i.t. administration of the P5-primed T cells on day -7 alone significantly prolonged graft survival (15.0+/-0.7 days) and when combined with 0.5 ml ALS led to donor-specific permanent graft survival. The long-term unresponsive recipients permanently (>100 days) accepted second-set donor-specific cardiac allografts but not third-party (Lewis) grafts. CONCLUSIONS: These findings demonstrate that the adoptive transfer of splenic T cells primed to an indirectly presented donor peptide induces transplantation tolerance in a transiently immunosuppressed secondary syngeneic recipient. Our data suggest that the interaction of thymic DC with activated peripheral T cells induces alloantigen (Ag)-specific T-cell tolerance by either inactivation or deletion of alloreactive T cells in the thymus. This observation provides the first formal evidence that the interaction between thymic DC and activated peripheral T cells that continuously circulate through the thymus plays an important role in the induction and maintenance of Ag-specific tolerance.

Adoptive Transfer↗
PubMed2001

Laparoscopic assisted percutaneous drainage of infected pancreatic necrosis.

BACKGROUND: Percutaneous drainage of infected pancreatic fluid collections is often unsuccessful. Alternatively, open necrosectomy techniques are very morbid. We hypothesized that in selected cases, laparoscopic techniques could be used to facilitate percutaneous drainage of the residual particulate necrosectum and avoid a laparotomy. We report our experience with laparoscopic assisted retroperitoneal debridement as an adjunct to percutaneous drainage for patients with infected pancreatic necrosis. METHODS: Case studies were reviewed retrospectively. We analyzed the course of six patients undergoing laparoscopic assisted debridement of infected pancreatic necrosis after failure of percutaneous drainage. With the drains and computed tomography (CT) scan used as a guide, laparoscopic debridement of the necrosectum was performed. RESULTS: Between November 1995 and December 1999, six patients were treated with this method. In four patients, laparoscopic assisted percutaneous drainage was successful. Two patients required open laparotomy. Complications included a self-limited enterocutaneous fistula and a small flank hernia. No deaths occurred. CONCLUSIONS: This early, limited experience has demonstrated the feasibility of laparoscopic assisted percutaneous drainage for infected pancreatic necrosis. With this technique, two-thirds of our patients avoided the morbidity of a laparotomy.

Abdominal Muscles↗
PubMed2001

Reduction in QT dispersion with rheolytic thrombectomy in acute myocardial infarction: evidence of electrial stability with reperfusion therapy.

An increase in QT dispersion (QTd) is associated with myocardial ischemia and may serve as a marker of ischemia and ventricular arrhythmia. We studied the effect of early reperfusion with rheolytic thrombectomy using an angiojet catheter (Possis, Minneapolis, MN) on QTd in 12 patients who presented with acute myocardial infarction. QTd and QT dispersion, rate-corrected for RR interval, were significantly reduced from 57 +/- 16 and 68 +/- 13 msec before reperfusion to 34 +/- 16 and 44 +/- 19 msec after reperfusion respectively (mean +/- SD; P < 0.002 and P < 0.0008, respectively). Successful reperfusion with rheolytic thrombectomy reduces QTd and may confer electrical stability to vulnerable myocardium. Reduction in indexes of repolarization inhomogeneity with reperfusion may serve as a noninvasive marker of coronary patency.

Aged↗
PubMed2001

Genomic heterogeneity in Pea seed-borne mosaic virus isolates from Pakistan, the centre of diversity of the host species, Pisum sativum.

A range of isolates of Pea seed-borne mosaic virus (PSbMV) was compared in the segments of the genome representing the partial NIb/CP/UTR and the partial P1-Pro/HC-Pro coding regions. Nucleotide and amino acid sequences, and a phylogenetic analysis of the CP region, divided isolates with available sequence information into two groups, one representing pathotype 4, the other pathotype 1. The pathotype 1 group showed greater diversity than the pathotype 4 group. A comparison of 14 isolates, S6 (a pathotype 4 isolate), US (a pathotype 1 isolate) and 12 isolates from Pakistan, by ribonuclease protection assay (RPA) using cRNA transcripts of the cloned partial NIb/CP/UTR regions of the S6, US and Pakistani isolate PK9 placed them into three distinct phylogenetic groups. RPA with a partial P1-Pro/HC-Pro cRNA probe identified a greater level of variation which was too high to be used for generating an overall phylogeny. Thus, RPA identified greater molecular diversity in PSbMV than described hitherto. We conclude that, in addition to the pathotypes 1 and 4 typified by US and S6 respectively, isolates of PSbMV from Pakistan include previously unrecognised molecular variants, and this accords with our previous recognition of new pathotypes from Pakistan.

Amino Acid Sequence↗
PubMed2001

Management of non-unions with mono-lateral external fixation.

UNLABELLED: We reviewed a cohort of 107 patients (110 long bone segments) with fracture non-union, treated by mono-lateral external fixation in Sheffield between 1987 and 1996. There were 83 males and 24 females with a mean age of 36 years. Sixty-seven patients had high-energy injuries and there were 56 open fractures. There were 60 tibiae, 38 femora and the rest were upper limb long bones with a mean of 3.2 previous procedures. The mean duration of non-union was 23.4 months (range 3-123). There were 61 mono-focal procedures with 41 supported in neutralisation, 20 in compression and three in distraction. There were 49 bifocal procedures (33 compression distraction and 16 bone transport). Seventy-one segments required a bone graft. The success rate using the initial fixator was 90%. Seven patients required further fixation to achieve clinical and radiological union, bringing the healing rate to 95.5% (total n=105). There were five amputations, all in smokers and three of them were directly related to vascular failure. The mean hospital stay was 21 days and the mean number of operations per patients was 2.55. The mean time to bony union was 12.69 months (range 2.5-64). The mean length gain was 4.5 cm (range 1.5-12 cm), the mean angular correction achieved was 12 degree (range 2-39 degree). The bony and functional results were assessed at the end of treatment by system described by Paley and Catagni (JBJS 77A, 1995). CONCLUSIONS: Mono-lateral external fixation can provide stable fixation for the treatment of established non-unions. The fracture environment may be carefully controlled and angulation and length corrected simultaneously. Interestingly 11 out of 12 problem cases were in smokers.

Adolescent↗
PubMed2001

Transport of viral proteins to the apical membranes and interaction of matrix protein with glycoproteins in the assembly of influenza viruses.

Influenza virus assembly and morphogenesis require transport of viral components to the assembly site at the apical plasma membrane of polarized epithelial cells and interaction among the viral components. In this report we have discussed the apical determinants present in the transmembrane domain (TMD) of influenza virus hemagglutinin (HA) and neuraminidase (NA), and the interaction of M1 with influenza virus HA and NA. Earlier studies have shown that the NA and HA TMDs possess determinant(s) for apical sorting and raft-association (Kundu et al., 1996. J. Virol 70, 6508-6515; Lin et al., 1998. J. Cell Biol. 142, 51-57). Analysis of chimeric constructs between NA and TR (human transferring receptor) TMDs and the mutations in the NA and HA TMD sequences showed that the COOH terminus of the NA TMD and NH(2) terminus of the HA TMD encompassing the exoplasmic leaflet of the lipid bilayers were significantly involved in lipid raft-association and that apical determinants were not discrete sequences but rather dispersed within the TMD of HA and NA. These analyses also showed that although both signals for apical sorting and raft-association resided in the NA TMD, they were not identical and varied independently. Interactions of M1 protein with HA or NA, the influenza virus envelope glycoproteins, were investigated by TX-100 detergent treatment of membrane fractions and floatation in sucrose gradients. Results from these analyses showed that the interaction of M1 with mature HA and NA, which associated with the detergent-resistant lipid rafts caused an increased detergent-resistance of the membrane-bound M1 and that M1 interacted with HA and NA both in influenza virus-infected cells as well as in recombinant vaccinia virus-infected cells coexpressing M1 with HA and/or NA. Furthermore, both the cytoplasmic tail and the TMD of HA caused an increased detergent-resistance of the membrane-bound M1 supporting their interaction with M1. Immunofluorescence analysis by confocal microscopy also showed colocalization supporting the interaction of M1 with HA and NA at the cell surface and during exocytic transport both in influenza virus-infected cells as well as in coexpressing cells.

Amino Acid Sequence↗
PubMed2001

The pattern of expression of the 5T4 oncofoetal antigen on normal, dysplastic and malignant oral mucosa.

The human 5T4 oncofoetal antigen is expressed by all types of trophoblast in pregnancy but is not detected on most adult tissues, although low levels are found on some epithelia. However, this antigen is strongly expressed by many cancers and tumour-associated labelling correlates with metastatic spread and poor clinical outcome for patients with gastric and colon cancer. Over-expression of the gene influences cell adhesion, shape and motility, which may be related to changes in the cellular localisation of the 5T4 oncofoetal antigen as malignancy develops. To establish whether the 5T4 oncofoetal antigen can serve as a tumour-specific marker for oral cancer and precancer, we have evaluated the pattern of expression on biopsies of normal, inflamed and dysplastic oral mucosa using immunohistochemistry. Oral mucosa, taken from different sites in the mouth, expressed the 5T4 oncofoetal antigen with varying intensity and pattern. The majority of the immunoreactivity was detected in the basal and suprabasal layers, with expression extending into the spinous cells at fully keratinised sites and when inflammation was present. This antigen was also detected in the underlying connective tissue. Oral squamous cell carcinoma showed a variety of patterns and intensity of staining corresponding to those found for normal mucosa. However, 21 of 41 cases showed no stromal labelling, a finding also observed for dysplastic lesions. The alterations in the pattern and intensity of 5T4 oncofoetal antigen expression were not related to clinicopathological features of the tumours examined. These data show that the 5T4 oncofoetal antigen is expressed on normal oral mucosa, such that this target cannot be used for detection of neoplastic or preneoplastic cells, although altered expression may contribute to the pathogenesis of these lesions.

Adult↗
PubMed2001

Laboratory and field evaluation of insect repellents as oviposition deterrents against the mosquito Aedes albopictus.

Three experimental approaches were used to evaluate the oviposition deterrency of three insect repellents, AI3-35765, AI3-37220 (piperidine compounds), and the standard N,N-diethyl-3-methylbenzamide (deet) to the mosquito Aedes albopictus Skuse (Diptera: Culicidae). Against laboratory-reared Ae. albopictus gravid females, the EC50 values of AI3-37220, AI3-35765 and deet were 0.004%, 0.008% and 0.011% in laboratory cages and 0.004%, 0.01% and 0.009% in an outdoor screened cage. For a natural population of Ae. albopictus tested in the field, the EC50 values were determined as 0.004%, 0.008% and 0.001%, respectively. Ageing concentrations of 0.1% of each repellent provided >50% effective oviposition deterrency against the laboratory population of Ae. albopictus for 13 days in laboratory cages, for 15 days in the outdoor cage, and for 21 days against field population of Ae. albopictus in Florida. These topical skin repellents are effective oviposition deterrents for Ae. albopictus when employed at relatively low application rates.

Aedes↗
PubMed2001

Laboratory and field evaluation of insect repellents as larvicides against the mosquitoes Aedes albopictus and Anopheles albimanus.

Acute toxicity and persistence of three insect repellents, deet and two piperidines (AI3-35765 and AI3-37220), were evaluated against mosquito larvae of Aedes albopictus (Skuse) and Anopheles albimanus Wiedemann (Diptera: Culicidae) in the laboratory, and against natural populations of Ae. albopictus in the field. In laboratory studies, the LC50 values of the repellents for first instars ranged between 0.005 and 0.021% (Ae. albopictus) and between 0.01 and 0.014% (An. albimanus) and, for fourth instars, between 0.019 and 0.034% (Ae. albopictus) and between 0.015 and 0.024% (An. albimanus). A 0.1% concentration of deet caused 90-100% mortality in first-instar Ae. albopictus for 4 weeks, whereas AI3-35765 and AI3-37220 at the same concentration killed 95-100% of larvae for 12 weeks and 98-100% of larvae for 33 weeks post-treatment, respectively. Deet and AI3-35765 at 0.1 % concentration resulted in complete mortality of first-instar An. albimanus for 3 weeks post-treatment, whereas AI3-37220 resulted in 91-99% larval mortalities for 35 weeks post-treatment. A 0.1% concentration of A13-37220 provided 77-98% larval mortality for 20 weeks and 63-97% larval mortality for 12 weeks post-treatment, respectively, against fourth-instar Ae. albopictus and An. albimanus. In the field, in artificial containers, the reduction of Ae. albopictus larvae caused by deet, AI3-35765 and AI3-37220 was 88-95% for 3-4 weeks, 98-100% for 7 weeks, and 82-100% for 13 weeks post-treatment, respectively. In used tyres, the same concentration of the repellents resulted in 100% reduction of Ae. albopictus larvae for 2 weeks (deet), 4 weeks (AI3-35765) and 5 weeks (AI3-37220) post-treatment. In cemetery flower vases, Aedes spp. larvae were eliminated for 4 weeks (deet) and 6 weeks post-treatment by both A13-35765 and AI3-37220. These topical repellents (particularly AI3-37220) have good potential for development and use in the management of container-inhabiting mosquitoes because they deter oviposition and kill larvae.

Aedes↗