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Biomedical subjects

M Ahmed

Publications and source records attributed to M Ahmed.

At least 91 records · Page 5Linked to original sources
PubMed2001

Isolation and characterization of differentially expressed genes in invasive and non-invasive immortalized murine male germ cells in vitro.

In an attempt to elucidate the potential of premeiotic male germ cells to malignant transformation both the invasiveness and the differential gene expression of several putative tumor markers of the spermatogonia-derived cell line GC-1spg and the spermatocyte-derived cell line GC-4spc were analyzed. Studies, using RT-PCR analysis, of the expression pattern of the alkaline phosphatase isoenzymes which serve as markers for testicular germ cell tumors demonstrated that the expression of the endogenous mouse embryonic alkaline phosphatase (EAP) is upregulated in the GC-1spg cell line. Additionally, after transfection of GC-1spg cells and GC-4spc cells with a GCAP-CAT construct, an increased promoter activity of the human germ cell alkaline phosphatase (GCAP), the equivalent human isoenzyme of EAP, was shown in GC-1spg. Furthermore, an in vitro Matrigel invasion assay revealed a significant higher invasive potential of GC-1spg cells as compared to GC-4spc cells. Finally, a suppression subtractive hybridization on RNA of invasive GC-1spg cells and non-invasive GC-4spc cells was performed. In total, 31 cDNA sequences were isolated and further analyzed. Among these, 18 known sequences and 13 unknown sequences were determined. Northern blot analysis revealed that one unknown gene and eight known genes, namely integrin alpha 6, L6 antigen, annexin VIII, BVL-1 retrotransposon, protective protein, replacement variant histone 3.3, alpha-catenin and LPS-binding protein, are over-expressed in invasive GC-1spg cells. Taken together, both the enhanced invasive activity of GC-1spg cells and the upregulated expression of genes involved in the process of tumor progression suggest that the immortalized spermatogonia-derived cell line GC-1spg does have a higher potential to malignant transformation than the immortalized spermatocyte-derived cell line GC-4spc.

Animals↗
PubMed2001

Analgesic, diuretic, and anti-inflammatory principle from Scoparia dulcis.

Scoparinol, a diterpene, isolated from Scoparia dulcis showed significant analgesic (p < 0.001) and anti-inflammatory activity (p < 0.01) in animals. A sedative action of scoparinol was demonstrated by a marked potentiation of pentobarbital-induced sedation with a significant effect on both onset and duration of sleep (p < 0.05). Measurement of urine volume after administration of scoparinol indicated its significant diuretic action.

Algorithms↗
PubMed2001

In vitro effects of acth on pigeon crop-sac epithelium.

ACTH in vitro produces non-specific crop-sac epithelium response. Crop-sac maintained in 10 IU.ACTH in isologous serum at 37 degrees C for 6 hrs. showed an increase of 105 +/- 0.95 mg for 12 hrs. 115 +/- 1.13 mg, for 18 hr. 125 +/- 0.95 mg. and for 24 hrs. 145 +/- 2.31 mg. The results were analyzed statistically by ANOVA technique. A significant rise in mean weight. In ACTH treated crop-sac, indicates a time related relationship (P < 0.01, ANOVA, Table 2). Thus present data indicates that there is a correlation between the epithelial response and initiation of ACTH present in the serum.

Journal Article↗
PubMed2000

Lamivudine without HBIg for prevention of graft reinfection by hepatitis B: long-term follow-up.

BACKGROUND: This open, multicenter study was conducted to evaluate the efficacy and safety of lamivudine prophylaxis given to chronic hepatitis B virus-(HBV) infected patients before and after orthotopic liver transplantation (OLT). We now present long-term data that follow our previous short-term report. METHODS: Twenty-three patients were treated with lamivudine (100 mg orally, daily); 13 (57%), were serum HBV DNA positive (Abbott Genostics, Abbott Laboratories, Chicago, IL) at study entry. Patients received lamivudine for at least 4 weeks before OLT, and for up to 50 months (median 25 months) after OLT. RESULTS: Of the 23 treated patients, 17 survived to undergo OLT. Eleven patients (65%) survived up to 4 years (median 36 months) after OLT. One of the survivors stopped lamivudine because of a possible adverse reaction 9 months post-OLT, and prophylaxis with HBV immune globulin was then established. Ten survivors continue lamivudine. Eight long-term survivors have normal liver function without evidence of HBV reinfection. Of the 17 transplanted patients, 6 died. Four patients died (3 days to 5 months post-OLT) without evidence of graft reinfection. Two further patients died at 19 and 23 months post-OLT from graft failure. Both patients had YMDD variant detected at 12 months post-OLT. Two other patients with YMDD-variant HBV remain alive on lamivudine, 9 and 15 months after development of the variant. CONCLUSIONS: Lamivudine, given before and after OLT, prevents significant graft reinfection for the majority of treated patients. The study has also shown that lamivudine is extremely well tolerated by liver failure patients and for a prolonged period after transplantation.

Biopsy↗
PubMed2000

Tandem ireland-claisen rearrangement ring-closing alkene metathesis in the construction of bicyclic beta-lactam carboxylic esters.

4-Alkenyl-2-azetidinone systems were converted to the corresponding ethyl 2-¿4-alkenyl-2-oxo-1-azetidinyl-4-pentenoates. In addition, 4-(2-propenyl-1-oxy)-, 4-(2-propenyl-1-thio)-, 4-¿N-(2-propenyl)-(4-toluenesulfonyl)- and (3S, 4R)-4-(2-propenyl)-3-¿(1R)-1-(tert-butyldimethylsilyloxy)ethyl-++ +azeti din-2-one were converted into beta-lactam dienes via sequential N-alkylation, Ireland-Claisen ester enolate rearrangement and esterification. Ring-closing metathesis using the Schrock ¿(CF(3))(2)MeCO(2)Mo(=CHCMe(2)Ph)(=NC(6)H(3)-2,6-iso-Pr(2)) (1) or Grubbs Cl(2)(Cy(3)P)(2)Ru=CHPh (2) carbenes gave a series of ¿5.2.0 and ¿6.2.0 bicycles. Subsequent elaboration of the analogous (2R,7R, 8S)-tert-butyl 8-¿(1R)-(tert-butyldimethylsilyloxy)ethyl-1-aza-9-oxobicyclo++ +¿5.2. 0non-4-ene-2-carboxylate (15), via selenation and desilylation, gave (+)-(2S,7R,8S)-tert-butyl 8-¿(1R)-hydroxyethyl-1-aza-9-oxobicyclo¿5.2.0nona-2, 4-diene-2-carboxylate (18), a novel type of bicyclic beta-lactam. Diels-Alder cycloaddition further afforded tetracyclic systems exemplified by tert-butyl (1R,4S,5R,7S)-4-¿(1R)-1-hydroxyethyl-3,9, 11-trioxo-10-phenyl-2,8,10,12-tetraazatetracyclo¿5.5.2.0.(2, 5)0(8, 12)tetradec-13-ene-1-carboxylate (19).

Alkenes↗
PubMed2000

Electronic absorption spectra of benzoquinone and its hydroxy substituents and effect of solvents on their spectra.

The electronic absorption spectra of 1,4-benzoquinone (BQ) and its 2,5-dihydroxy and tetrahydroxy derivatives have been studied in detail. The interpretation of the electronic bands is made on the basis of PPP and CNDO calculations. It is found that the pi --> pi* transitions are well predicted by the PPP method. The predictions of the CNDO method are however superior both in their accuracy as well as ability to predict the n --> pi* transitions. The effect of solvents on the electronic absorption bands have also been investigated in detail. Linear correlations are found between the solvent's dielectric constant and wavelength of the absorption bands. The solvent shifts are explained on the basis of the polarities of the solute and solvent molecules as well as due to hydrogen bonding.

Benzoquinones↗
PubMed2000

ACTH-producing pituitary cancer: experience at the King Faisal Specialist Hospital & Research Centre.

Pituitary gland is an uncommon site of a primary cancer. Of more than 600 cases of pituitary tumors seen at the KFSH&RC between 1975 to 1998 only 3 patients had primary pituitary cancer. We have previously reported a case of pituitary fibrosarcoma arising as a rare complication of external radiotherapy (ERT) for GH-secreting pituitary adenoma (PA) [1]. We report now 2 cases of ACTH-producing primary pituitary carcinoma (ACTH-PPC); their follow-up data provide information on the natural history of this cancer. Patient #1; a 46 year old lady with Cushing's disease (CD) presented with an enlarged right cervical lymph node (LN) 2 years after having undergone a partial hypophysectomy through transsphenoidal surgery (PHYPX/TSS) and ERT for an invasive pituitary tumor. Patient #2; a 26 year old man presented with CD and underwent bilateral adrenalectomy (ADx) and pituitary ERT. Thirty-nine months later he developed Nelson's syndrome and a PHYPX/TSS was performed. Incidentally discovered hepatic metastases in this patient and an excisional biopsy of the LN in patient #1 showed histological features very similar to the pituitary tumor, and they stained strongly positive for ACTH. Perinuclear spherical hyalinized cytoplasmic inclusions were seen in the LN biopsy that corresponded to bundles of type 1 microfilaments (specific for pituitary ACTH-producing cells) seen by electron microscopy. A whole body 18-Fluoro-2-Deoxy-D-Glucose positron emission (FDG-PET) scanning, showed an intense uptake in the neck mass. A trial of octreotide did not change the exceedingly high levels of ACTH in patient #2, further supporting the diagnosis of ACTH-PPC. The clinical course of 102 months prior to his demise showed continued progression of the primary and the metastatic tumor. Patient #1, is alive at 15 months follow-up; hypercortisolemia is controlled using ketoconazole. ACTH-PPC should be entertained in a patient with CD presenting with persistent cervical lymphadenopathy. The clinical course in our patients suggests that the emergence of PC may involve a proliferative continuum from a pre-existing PA to an invasive tumor, culminating in a carcinoma. Adjunctive events such as ERT/ADx may predispose to the evolution of PC in genetically susceptible individuals. Because ERT is an effective treatment for PA its use will continue; it is important to be aware of the possible complication of primary pituitary carcinoma.

Adrenocorticotropic Hormone↗
PubMed2000

The immediate replacement of teeth by dental implants using homologous bone membranes to seal the sockets: clinical and radiographic findings.

Placement of dental implants into fresh extraction sockets has several advantages compared to the original protocol. However, the soft-tissue handling is often complicated and the aesthetic results less rewarding. A method to use a homologous bone membrane as the sole sealer of the extraction socket after immediate implant placement is introduced and the outcome of 34 cases is presented. In 4 cases early losses of the membranes occurred (2 of these iatrogenic damage) in all other cases the homologous membranes were covered by proliferation of the surrounding mucosa within 2-4 weeks. In 2 of the 4 cases where the membranes were lost, the implants did not integrate, in the other 2 cases the implants did integrate but the sockets did not fill completely with bone and the aesthetic results were not acceptable. In all other cases bone filling of the socket occurred, the implants were stable at 180 days after insertion (functional success rate 94.1%) and the aesthetic results were excellent. The method thus seems very promising but the healing process is delicate and the operation site highly vulnerable during the first postoperative weeks. It should also be stressed that the present study offers conclusions neither about the quality of the newly formed bone nor about the quality of osseointegration offered by this bone.

Adolescent↗
PubMed2000

Biological effects induced by variable levels of BCR-ABL protein in the pluripotent hematopoietic cell line UT-7.

There is currently no satisfactory model allowing analysis of dose-effect relationships of BCR-ABL proteins in human hematopoietic cells. To study comparatively the proliferative, differentiative and anti-apoptotic actions of different levels of BCR-ABL proteins in the context of the same cellular background, we have introduced the BCR-ABL gene into the GM-CSF-dependent pluripotent human cell line UT-7. Individual clones expressing BCR-ABL were analyzed by Western blots. After normalization to equivalent levels of endogenous ABL protein, 14 clones always grown in GM-CSF were found to express low but variable levels of BCR-ABL whereas two clones selected in the absence of GM-CSF expressed very high levels of BCR-ABL. All low-level BCR-ABL expressing clones exhibited a behavior similar to that of the GM-CSF-dependent parental cells as they ceased to proliferate upon growth factor deprivation and showed a strong proliferative response upon GM-CSF addition. One out of 14 clones showed progressive GM-CSF independence during culture over several weeks and was found to have a significant increase of BCR-ABL expression at that time. The resistance of this clone (E8-2) to different apoptotic stimuli was found to be increased as compared to its low BCR-ABL-expressing counterpart (E8-1) and similar to that observed in clones with very high levels of BCR-ABL (UT-7/9 and UT-7/11) which were totally resistant to apoptotic stimuli. When injected into nude mice, parental UT-7 cells and clones with low-level of BCR-ABL were not tumorigenic over 10 weeks of observation whereas UT-7 clones with high levels of BCR-ABL (UT-7/9, UT-7/11 and UT-7/E8-2) induced aggressive tumors in 2-4 weeks with a significant correlation between the amount of BCR-ABL protein and the rate of tumor growth. In conclusion, the establishment of an in vitro and in vivo CML model using UT-7 cells suggests for the first time in human cells, that the fully transformed phenotype induced by BCR-ABL requires high levels of BCR-ABL expression. These findings suggest that variable levels of BCR-ABL in primary patient cells could also be responsible for the different phenotypic features seen in chronic and acute phases of CML, such as the differentiation ability induced by growth factors.

Animals↗
PubMed2000

Syntheses and cytotoxic, antimicrobial, antifungal and cardiovascular activity of new quinoline derivatives

New derivatives of quinoline (CAS 91-22-5, Z-1) were synthesized and their potential therapeutical significance and structure-activity relationship were tested. The brine shrimp bioassay was carried out to study their in vitro cytotoxicity, and besides, also their antimicrobial, antifungal and cardiovascular activities were investigated. Some structures showed a high degree of activity on the isolated rabbit jejunum. Extensive spectroscopic techniques such as EIMS, FABMS, peak matching MS, UV, IR and 1H NMR were employed to confirm the structure of the synthetic products.

Journal Article↗
PubMed2000

Inhibition of coronary thrombosis and local inflammation by a noncarbohydrate selectin inhibitor.

We tested the hypothesis that selectin inhibition with blocking antibodies or a small-molecular-weight inhibitor of L-, P-, and E-selectin, methoxybenzoylpropionic acid (MBPA), prevents thrombus formation in a canine coronary Folts' model. Cyclic flow variations (CFVs) were induced by crush injury and constriction of the left anterior descending coronary artery in dogs. Systemic infusion of antibodies to P- and L-selectin abolished CFVs, respectively, in 50% and 17% of treated dogs [P = not significant (NS)]. The combination of P- and L-selectin antibodies suppressed CFVs in 60% of treated dogs (P = NS). In contrast, systemic selectin blockade by intravenous infusion or local adventitial application of MBPA markedly reduced CFVs and, in addition, reduced myocardial myeloperoxidase (MPO) activity. We conclude that inhibition of L-, P-, and E-selectin binding by a small-molecular-weight, noncarbohydrate compound markedly reduces arterial thrombosis, whereas systemic administration of antibodies to L- and P-selectin fail to reproduce this antithrombotic effect. These results underscore the role of selectins in the pathogenesis of arterial thrombosis under high shear stress and suggest that inhibition of P- and L- selectin may not suffice to prevent thrombus formation in this model. The role of E-selectin in thrombus formation in this model awaits further testing.

Animals↗
PubMed2000

Periodontal signs and symptoms associated with vertical root fracture.

This report describes the clinical presentation of three cases of vertical root fractures in adult patients where an initial diagnosis of localized periodontitis had been considered. Loss of the affected tooth occurred in all of these patients. The effects of endodontic therapy and the provision of post-retained restorations are considered in relation to their potential effect of weakening the root and predisposing the tooth to vertical fracture. The last case presents an unrestored molar tooth with a complete vertical root fracture.

Adult↗