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Biomedical subjects

M Lee

Publications and source records attributed to M Lee.

At least 415 records · Page 23Linked to original sources
PubMed1997

EGF inhibits expression of WDNM1 and sulfated glycoprotein-2 genes in mammary epithelial cells.

We have previously shown that expressions of ferritin heavy chain (FHC), WDNM1, and sulfated glycoprotein-2 (SGP-2) genes are induced at an involution stage of mammary gland. Here we studied the effect of lactogenic hormones and EGF on the expression of involution-induced genes in HC11 mammary epithelial cells. Insulin, dexamethasone, prolactin, and its combinations did not affect expression of the genes. When cells were cultured in growth medium containing EGF, expression of WDNM1 and SGP-2 genes was strongly inhibited in a dose- and time- dependent manner, whereas expression of FHC gene was not influenced by EGF. Results demonstrate that EGF inhibits expression of WDNM1 and SGP-2 genes in mammary epithelial cells.

Animals↗
PubMed1997

Therapeutic effects of leuprorelin microspheres in prostate cancer.

Leuprorelin has demonstrated effectiveness comparable to orchiectomy and oral diethylstilboestrol for the palliation of advanced prostate cancer. Unlike orchiectomy, leuprorelin's effects are reversible; also leuprorelin is not associated with the cardiovascular or thromboembolic adverse effects of oestrogens. For these reasons, leuprorelin has been widely used as an alternative to surgical castration or to oestrogens in the treatment of metastatic prostate cancer. Sustained-release leuprorelin microsphere formulations have been developed which exhibit zero order release of active drug from the injection site, such that in the United States the 7.5 mg dosage strength is recommended to be administered once a month and the 22.5 mg dosage strength once every three months. Although most patients will have suppressed release of pituitary luteinizing hormone by the third or fourth week after the first dose of depot leuprorelin, 4-5% of treated patients have been reported to have delayed responses, taking many more weeks or months to respond. A transient biochemical hormone escape has also been reported, although worsening of clinical symptoms has not accompanied the elevation of serum testosterone levels during treatment. Usually, leuprorelin is initiated as monotherapy when patients with advanced prostate cancer become symptomatic. However, newer studies of combination therapy of luteinizing hormone releasing hormone analogs with antiandrogens suggest that early initiation of therapy, at the time of diagnosis of advanced disease, may be beneficial, particularly in a subgroup of patients with small volume disease and good performance status. Leuprorelin is also undergoing evaluation as neoadjuvant therapy prior to radical prostatectomy for localized prostate cancer. Preliminary studies suggest that neoadjuvant leuprorelin in combination with an antiandrogen may be effective in downstaging prostate tumours. Leuprorelin commonly produces several adverse effects: hot flashes, decreased libido and impotence, and tumour flare.

Journal Article↗
PubMed1997

Induction of basic fibroblast growth factor (bFGF) expression following focal cerebral ischemia.

Basic fibroblast growth factor (bFGF) is a biologically active polypeptide with mitogenic, angiogenic, and neurotrophic properties. In the present study, we examined the temporal and spatial expression profiles of bFGF mRNA and protein concentration in a focal cerebral ischemia model induced by transient occlusion of the right middle cerebral artery (MCA) and both common carotid arteries (CCAs). Results of Northern blot analysis shows a transient 2.5-fold increase in the 6.0 kb transcript of bFGF mRNA within the ischemic cortex of rats subjected to 60 min ischemic insult followed by 12 h of reperfusion. Although enhanced expression of bFGF mRNA was also noted in the ipsilateral hippocampus, the temporal induction profile appeared to be different from that of the ischemic cortex. A significant increase in bFGF mRNA was observed as early as 60 min following ischemia and remained elevated for up to 2 weeks after the onset of reperfusion. In situ hybridization studies revealed constitutive expression of bFGF mRNA in discrete brain regions of sham-operated animals. Following 60 min ischemia and 12 h reperfusion, increased expression of bFGF mRNA was observed in the ischemic cortex (both peri-infarct and infarct area). Increased expression of bFGF mRNA within the infarcted area is largely confined rostrally to the outer cortical layers of the infarct, an area with increased density of blood vessels. bFGF-like immunoreactivity was also detected in areas expressing bFGF mRNA. Furthermore, a striking increase in bFGF-like immunoreactivity was observed in the ipsilateral hippocampus. Double-staining with anti-GFAP antibody indicated that the majority of the bFGF-like immunoreactivity was localized in the astrocytes, however, not all astrocytes showed bFGF-like immunoreactivity. Some GFAP negative cell also showed bFGF-like immunoreactivity. In summary, increased expression of both bFGF mRNA and immunoreactivity following ischemia were located in the same brain regions. An increase in bFGF-like immunoreactivity after ischemic insult is likely due to an increase in the expression of its 6.0 kb bFGF mRNA transcripts. Although increased bFGF mRNA was observed in both ischemic cortex and ipsilateral hippocampus after ischemic insult, the temporal expression profiles differed. Results from the present study raise the possibility that increased expression of bFGF in the peri-infarcted area may limit the spread of ischemic injury.

Animals↗
PubMed1997

A bioluminescent assay for agonist activity at potentially any G-protein-coupled receptor.

Transient expression of apoaequorin in Chinese hamster ovary (CHO) cells and reconstitution with the co-factor coelenterazine resulted in a large, concentration-dependent agonist-mediated luminescent response following cotransfection with the endothelin ETA, angiotensin ATII, thyrotropin-releasing hormone (TRH), and neurokinin NK1 receptors, all of which interact pre-dominantly with the G alpha q-like phosphoinositidase-linked G-proteins. A substantially greater luminescence was obtained with mitochondrially targeted apoaequorin compared to cytoplasmically expressed apoaequorin. To generate a system amenable for the study of agonist activity at virtually any G-protein-coupled receptor the alpha subunit of the receptor promiscuous G-protein G alpha 16 was either transiently or stably expressed in CHO cells together with apoaequorin. In cells expressing G alpha 16, but not in its absence, agonists at a series of receptors which normally interact with either G alpha s or G alpha i were now able to cause a luminescent response from mitochondrially targeted apoaequorin. In the case of the A1 adenosine receptor, this response was clearly a result of activation of G alpha 16 and not a consequence of the release of the G alpha i-associated beta/gamma complex, as the luminescent response was unaffected by pertussis toxin treatment of the cells, whereas agonist-mediated inhibition of adenylyl cyclase activity was attenuated. These studies describe the use of coexpressed apoaequorin as a reporter for G-protein-coupled receptor-mediated calcium signaling. Furthermore, coexpression of G alpha 16 and apoaequorin provides a basis for a generic mammalian cell microplate assay for the assessment of agonist action at virtually any G-protein-coupled receptor, including orphan receptors for which the physiological signal transduction mechanism may be unknown.

Adenosine-5'-(N-ethylcarboxamide)↗
PubMed1997

Protein carbonyl formation in blood plasma by cephalosporins.

Cephalosporin antibiotics caused the formation of carbonyl groups in the plasma proteins both in vivo and in vitro. After the administration of either moxalactam (3 g/day) or cefotaxime (2 g/day) to patients for 7 days, the carbonyl contents in the plasma proteins increased markedly as determined by the 2,4-dinitrophenylhydrazine (DNPH) method. The increase in protein carbonyl groups was also visualized by the conjugation of plasma proteins with fluorescein thiosemicarbazide (FTSC) and subsequent electrophoresis. When blood plasma was incubated with cephalosporins, most of the cephalosporins tested caused the carbonyl formation in plasma proteins to significant degrees in a concentration-dependent manner. Although a number of plasma proteins and other nonplasma proteins could be modified by cephalosporins in vitro, the plasma albumin was most markedly modified in vivo as well as in vitro. The protein carbonyl formation by cephalosporins was inhibited by ascorbic acid, reduced glutathione, and cysteine, but it was not affected by FeSO4, CuSO4, desferrioxamine, EDTA, catalase, superoxide dismutase, uric acid, alpha-tocopherol, and mannitol. Sodium borohydride, when applied to moxalactam-treated plasma proteins, markedly reduced the reactivities of the protein with FTSC or DNPH, indicating that the observed reactivities of the cephalosporin-treated proteins toward FTSC or DNPH are actually due to the protein carbonyl groups. These data suggest that cephalosporins can oxidatively modify proteins in blood plasma and other tissues and that the oxidative modification of proteins may be involved in the adverse reactions observed frequently following cephalosporin therapy.

Antioxidants↗
PubMed1997

Lack of effect of estrogen on rest and treadmill exercise in postmenopausal women without known cardiac disease.

To assess the peripheral vascular effects of estrogen in women without coronary disease, normal postmenopausal women (mean age 56 +/- 8 years) participated in a randomized, crossover trial using treadmill exercise echocardiography, and received oral conjugated estrogen, 0.625 mg/day or underwent a drug-free period. There was no significant effect on heart rate, blood pressure, double product, left ventricular end-systolic and end-diastolic diameters, or electrocardiographic measures after estrogen. In contrast to the profound effects reported in patients with cardiac disease, oral estrogen in normal women does not bestow significant benefit on treadmill exercise echocardiographic variables at rest or during modest levels of exercise.

Adult↗
PubMed1997

Genetic evidence for selective degradation of RNA polymerase subunits by the 20S proteasome in Saccharomyces cerevisiae.

scs32 was isolated as an extragenic suppressor of a temperature-sensitive (ts) mutation (rpo26-31) in the gene encoding Rpo26p, a subunit common to yeast nuclear RNA polymerases (RNAPs). rpo26-31 also confers inositol auxotrophy, inhibits the assembly of RNAPI and RNAPII and reduces the steady-state level of Rpo26p and the largest subunit of RNAPI (Rpo11p or A190p) and RNAPII (Rpo21p). rpo26-31p accumulated to wild-type levels in the scs32 strain; nevertheless, the amount of assembled RNAPII remained at a reduced level at high temperature. Hence, scs32 only partially suppressed the ts phenotype and was unable to suppress the Ino-phenotype of rpo26-31. SCS32 is identical to PUP3, which encodes a subunit of the yeast proteasome. scs32 was able to suppress the phenotype of other ts alleles of RPO26, all of which reduce the steady-state level of this subunit. However, scs32 was unable to suppress the ts phenotype of mutant alleles of RPO21, or result in accumulation of the unstable rpo21-4p. These observations suggest that the stability of non-functional or unassembled forms of Rpo26p and Rpo21p are regulated independently.

Amino Acid Sequence↗
PubMed1997

A cysteine-3 to serine mutation of the G-protein Gi1 alpha abrogates functional activation by the alpha 2A-adrenoceptor but not interactions with the beta gamma complex.

Pertussis toxin-resistant (C351G) and also palmitoylation-negative (C3S/C351G), myristoylation-negative (G2A/C351G) and combined acylation-negative (G2A/C3S/C351G) forms of the G-protein Gi1 alpha were expressed in COS-7 cells along with the porcine alpha 2A-adrenoceptor. G2A/C3S/C351G Gi1 alpha and G2A/C351G Gi1 alpha were largely cytosolic and failed to interact with the agonist-occupied alpha 2A-adrenoceptor in membrane preparations. In contrast, C351G Gi1 alpha was almost entirely particulate and the alpha 2-adrenoceptor agonist UK14304 caused a marked stimulation of its GTPase activity and binding of [35S]GTP gamma S which was not prevented by pertussis toxin treatment of the cells. C3S/C351G Gi1 alpha was present in both the particulate and cytosolic fractions but the GTPase activity of the membrane bound fraction was only slightly activated by the alpha 2A-adrenoceptor. Coexpression of C3S/C351G Gi1 alpha and the alpha 2A-adrenoceptor along with beta 1 and gamma 2 subunits increased the P2 membrane complement of the alpha subunit and increased substantially the ratio of membrane bound to cytosolic protein. However, this also failed to allow marked stimulation of high-affinity GTPase activity by the alpha 2A-adrenoceptor despite the increased proportion of G-protein in the P2 membrane fraction. Despite the low fractional activation of C3S/C351G Gi1 alpha by the alpha 2A-adrenoceptor compared to C351G Gi1 alpha, the palmitoylation-resistant G-protein caused a marked reduction in pertussis toxin-resistant, agonist (UK14304)-mediated stimulation of adenylyl cyclase activity. UK14304 caused the same degree of effect on adenylyl cyclase activity in pertussis toxin-treated cells following transfection of the same amounts of C351G Gi1 alpha and C3S/C351G Gi1 alpha, as both appear to act to sequester beta gamma subunits. By contrast, neither G2A/C351G Gi1 alpha nor G2A/C3S/C351G Gi1 alpha resulted in effective regulation of adenylyl cyclase activity.

Adenylate Cyclase Toxin↗
PubMed1997

Magnetic resonance brain imaging in women with obsessive-compulsive disorder and trichotillomania.

Magnetic resonance imaging of the brain was undertaken in women with obsessive-compulsive disorder (n = 13), trichotillomania (n = 17), and healthy controls (n = 12). Caudate volume and ventricular-brain ratio (VBR) (variables that have previously been highlighted as abnormal in studies of OCD) were compared in the three subject groups and were correlated with neuropsychological and neurological soft sign findings. No significant differences were found between women with OCD, trichotillomania and normal controls on caudate volume or VBR. Decreased left caudate volume was significantly correlated with impairment on neuropsychological testing and with increased neurological soft signs. The negative findings here may indicate that in women with OCD and related disorders structural brain abnormalities are less obvious or less common than in men with these conditions, or they may reflect inadequate sensitivity of the brain measures employed.

Adult↗
PubMed1997

The genomic organization of the murine Pax 8 gene and characterization of its basal promoter.

Lambda phage clones containing the murine Pax 8 gene were isolated from a C57BL/6 kidney genomic mouse library using mouse cDNA fragments as probes. A clone encompassing about 16 kb of the 5' untranslated region of the murine Pax 8 gene was isolated from a mouse embryonic stem cell (D3) library. The murine Pax 8 gene has a size of approximately 26 kb and contains the coding sequence for mRNA in 12 exons. The major and several minor transcription initiation sites were identified. Position +1 is located 488 nucleotides upstream of the ATG initiation codon and 24 bases downstream of a TATA-like sequence, ATAAAA. The translation initiation and termination sites are located in exons 2 and 12, respectively. Further analysis of 570 bases of the 5' flanking sequence revealed AP2, SP1, PEA3, zeste, NF-kappaB, and CCAAT consensus binding sites. Ribonuclease protection assays with a probe spanning the first two exons of mouse Pax 8 cDNA on total RNA samples isolated from different tissues of newborn mice show that the murine Pax 8 gene is predominantly expressed in kidney tissue. Low levels of Pax 8 gene expression were also found in the liver, spleen, lung, brain, and heart. The same transcription initiation sites are utilized in different tissues of newborn mice and embryo at Day 10.5 postconception. A FISH assay shows that the murine Pax 8 gene is located on chromosome 2, map position B.

Animals↗
PubMed1997

The sequence specificity of alkylation for a series of benzoic acid mustard and imidazole-containing distamycin analogues: the importance of local sequence conformation.

The covalent sequence specificity of a series of nitrogen mustard and imidazole-containing analogues of distamycin was determined using modified sequencing techniques. The analogues tether benzoic acid mustard (BAM) and possess either one, two or three imidazole units. Examination of the alkylation specificity revealed that BAM produced guanine-N7 lesions in a pattern similar to conventional nitrogen mustards. The monoimidazole-BAM conjugate also produced guanine-N7 alkylation in a similar pattern to BAM, but at a 100-fold lower dose. The diimidazole and triimidazole conjugates did not produce detectable guanine-N7 alkylation but only alkylated at selected sites in the minor groove. Unexpectedly, the alkylation specificity at equivalent doses was nearly identical to that found for the previously reported pyrrole-BAM conjugates. The consensus sequence, 5'-TTTTGPuwas strongly alkylated by the triimidazole conjugate in preference to other similar sites including three occurrences of 5'-TTTTAA. Footprinting studies were carried out to examine the non-covalent DNA binding interactions. These studies revealed that the tripyrrole- BAM conjugate bound non-covalently to the same AT-rich sites as distamycin. In contrast, whereas the Im3lexitropsin bound non-covalently to GC-rich sequences, the triimidazole-BAM conjugate did not detectably footprint to either GC- or AT-rich regions at equivalent doses. The results indicate that the alkylation event is not solely dictated by the non-covalent binding and might be influenced by a unique sequence dependent conformational feature of the consensus sequence 5'-TTTTGPu.

Alkylation↗
PubMed1997

The reticulocalbin gene maps to the WAGR region in human and to the Small eye Harwell deletion in mouse.

We describe the localization of the gene encoding reticulocalbin, a Ca2+-binding protein of the endoplasmic reticulum, on human chromosome 11p13 midway between the WT1 and the PAX6 genes and show that it is hemizygously deleted in WAGR individuals. The mouse reticulocalbin gene is also shown to map to the region of conserved synteny on mouse chromosome 2 and to be deleted in the Small eye Harwell (SeyH) mutation. Loss of the reticulocalbin gene could contribute to the early lethality of SeyH and SeyDey homozygotes.

Abnormalities, Multiple↗
PubMed1997

Familial and personal medical history of cancer and nervous system conditions among adults with glioma and controls.

The causes of glioma, the most common type of primary malignant brain tumor, are poorly understood. This study compared the personal and first-degree familial medical histories of 462 adults newly diagnosed with glioma in the San Francisco Bay Area between August 1, 1991, and March 31, 1994, with those of 443 controls who were frequency-matched on age, sex, and ethnicity. Cases and controls had equivalent personal histories of cancers other than brain cancer and most nervous system conditions, but they differed significantly regarding histories of epilepsy, seizures, or convulsions 3 or more years prior to diagnosis (odds ratio = 3.3, 95% confidence interval (CI) 1.4-7.9), chickenpox (odds ratio = 0.4, 95% CI 0.3-0.6), and shingles (odds ratio = 0.5, 95% CI 0.3-0.8). Four cases (less than 1%) and no controls had known genetic disorders (three had neurofibromatosis and one had tuberous sclerosis). Cases and controls had similar family histories of cancer and seizures. However, the odds ratio for a validated family history of primary brain tumor was 2.3 (95% CI 1.0-5.8). These results suggest that although family history of any cancer probably is not an important risk factor for adult glioma, a family history of brain tumors may play a role. Variation in exposure to or biologic response to common viral infections might play a greater role in the etiology of adult glioma than family history.

Adult↗
PubMed1997

Does prior infection with varicella-zoster virus influence risk of adult glioma?

To evaluate a possible association between varicella-zoster virus infection and glioma, the authors asked adults with glioma (n = 462) whose tumors were diagnosed between August 1, 1991, and March 31, 1994, and age-, sex-, and ethnicity-matched controls (n = 443) about their histories of chickenpox or shingles. Cases were significantly less likely than controls to report a history of either chickenpox (odds ratio = 0.4, 95% confidence interval (CI) 0.3-0.6) or shingles (odds ratio = 0.5, 95% CI 0.3-0.8). To obtain serologic support for these findings, the authors conducted double-blind enzyme-linked immunosorbent assays for immunoglobulin G antibodies to varicella-zoster virus among 167 self-reporting subjects for whom blood samples were available. Cases and controls reporting no history of chickenpox were equally likely to test positive (73% vs. 75%), but among those reporting a positive history, cases were less likely than were controls to test positive (71% vs. 85%). Despite the misclassification, an odds ratio of 0.6 was obtained using either serologic data (95% CI 0.3-1.3) or reported history of chickenpox (95% CI 0.3-1.1) in this subgroup of subjects. This suggests that adults with glioma were less likely than controls either to have had prior varicella-zoster virus infection or to have an immunoglobulin G antibody response adequate to indicate positivity. Since either explanation suggests novel mechanisms for brain tumor pathogenesis, these findings require corroboration and elaboration.

Adult↗
PubMed1997

The chromosomal distribution of CpG islands in the mouse: evidence for genome scrambling in the rodent lineage.

We have prepared a library of mouse whole CpG islands using a methyl-CpG binding domain column. The distribution of CpG islands in the mouse genome was determined by FISH, using the library as a probe. Unlike in other vertebrate genomes that have been examined (human and chicken), extreme clustering of CpG islands was not seen in the mouse genome. No individual murine chromosome stood out as being either very gene-rich or very gene-poor. Despite the more even distribution of CpG islands in the mouse at a gross chromosomal level, at finer resolution concentrations of CpG islands are seen to correspond to the R-band early replicating regions of the genome.

Animals↗
PubMed1997

Amyloid precursor protein processing and A beta42 deposition in a transgenic mouse model of Alzheimer disease.

The PDAPP transgenic mouse, which overexpresses human amyloid precursor protein (APP717V-->F), has been shown to develop much of the pathology associated with Alzheimer disease. In this report, levels of APP and its amyloidogenic metabolites were measured in brain regions of transgenic mice between 4 and 18 months of age. While absolute levels of APP expression likely contribute to the rate of amyloid beta-peptide (Abeta) deposition, regionally specific factors also seem important, as homozygotic mice express APP levels in pathologically unaffected regions in excess of that measured in certain amyloid plaque-prone regions of heterozygotic mice. Regional levels of APP and APP-beta were nearly constant at all ages, while A beta levels dramatically and predictably increased in brain regions undergoing histochemically confirmed amyloidosis, most notably in the cortex and hippocampus. In hippocampus, A beta concentrations increase 17-fold between the ages of 4 and 8 months, and by 18 months of age are over 500-fold that at 4 months, reaching an average level in excess of 20 nmol of A beta per g of tissue. A beta1-42 constitutes the vast majority of the depositing A beta species. The similarities observed between the PDAPP mouse and human Alzheimer disease with regard to A beta42 deposition occurring in a temporally and regionally specific fashion further validate the use of the model in understanding processes related to the disease.

Age Factors↗
PubMed1997

Interactions of the alpha2A-adrenoceptor with multiple Gi-family G-proteins: studies with pertussis toxin-resistant G-protein mutants.

The alpha2A-adrenoceptor is the prototypic example of the family of G-protein-coupled receptors which function by activation of 'Gi-like' pertussis toxin-sensitive G-proteins. A number of members of this subfamily of G-proteins are often co-expressed in a single cell type. To examine the interaction of this receptor with individual Gi-family G-proteins the porcine alpha2A-adrenoceptor was transiently transfected into COS-7 cells either alone or with each of wild-type Gi1alpha, Gi2alpha and Gi3alpha or mutations of each of these G-proteins in which the cysteine residue which is the target for pertussis toxin-catalysed ADP-ribosylation was exchanged for a glycine residue. The alpha2-adrenoceptor agonist UK14304 stimulated both high-affinity GTPase activity and the binding of guanosine 5'-[gamma-35thio]-triphosphate (GTP[35S]), when expressed without any additional G-protein. These effects were greatly reduced by pretreatment of the cells with pertussis toxin. Co-expression of each of the wild-type Gi-like G-protein alpha-subunits resulted in enhanced agonist activation of the cellular G-protein population which was fully prevented by pretreatment with pertussis toxin. Co-expression of the receptor along with the cysteine-to-glycine mutations of Gi1alpha, Gi2alpha and Gi3alpha resulted in agonist stimulation of these G-proteins, which was as great as that of the wild type proteins, but now the agonist stimulation produced over that due to the activation of endogenously expressed Gi-like G-proteins was resistant to pertussis toxin treatment. The Cys --> Gly mutations of Gi1alpha, Gi2alpha and Gi3alpha were each also able to limit agonist-mediated stimulation of adenylate cyclase activity. The degree of agonist-mediated activation of the pertussis toxin-resistant mutant of Gi1alpha was correlated highly both with the level of expression of this G-protein and with the level of expression of the alpha2A-adrenoceptor. Half-maximal stimulation of high-affinity GTPase activity of the Cys --> Gly mutants of Gi1alpha, Gi2alpha and Gi3alpha required 10-15-fold higher concentrations of agonist than did stimulation of their wild-type counterparts, consistent with a model in which the affinity of functional interactions of the alpha2A-adrenoceptor with the wild-type G-protein is greater than with the pertussis toxin-resistant mutant G-protein.

Adenylate Cyclase Toxin↗