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Biomedical subjects

M Wang

Publications and source records attributed to M Wang.

At least 1,099 records · Page 61Linked to original sources
PubMedDate not supplied

Older persons' opinions about life-sustaining procedures in the face of dementia.

OBJECTIVE: To investigate the attitudes of cognitively normal older adults toward various life-sustaining procedures in the face of dementia. METHODS: Participants were 84 cognitively normal men and women (70% response rate), 65 years and older, from a variety of urban and suburban settings, including private homes, assisted-living apartments, transitional care facilities, and nursing homes. In-person interviews were conducted with each participant to obtain information about demographic characteristics, life and health, and desire for various life-sustaining procedures for 4 hypothesized levels of dementia. RESULTS: Approximately three fourths of participants said they would not want cardiopulmonary resuscitation, use of a respirator, or parenteral or enteral tube nutrition with the milder forms of dementia, and 95% or more of participants would not want these procedures with severe dementia. In addition, only one third or fewer participants thought they would want to be hospitalized or given antibiotics if they were severely demented. Logistic regression analysis showed a relationship between participants' desire for life-sustaining procedures and having less education, greater independence, and a higher perceived quality of life. CONCLUSIONS: Most surveyed individuals did not desire life-sustaining treatments with any degree of dementia, and the proportion of individuals not desiring such treatments increased with the projected severity of dementia. These findings indicate a need for including dementia in advance directives planning.

Advance Directives↗
PubMedDate not supplied

In vivo measurements of frequency-dependent attenuation in tumors of the liver.

Ultrasonic frequency-dependent attenuation (FDA) coefficients of the liver obtained from selected regions of interest within the liver were determined in 106 individuals, 40 cases presumed normal based on medical histories and 66 with malignant tumors (hepatocellular carcinoma [HCC] or metastatic liver tumor) or benign tumors (hepatic hemangioma, hepatic adenoma, or focal nodular hyperplasia of the liver). All liver tumors were confirmed histopathologically by ultrasonically guided fine-needle biopsy and/or operation. Mean attenuation of normal liver was 0.53 +/- 0.03 dB/cm/MHz, 0.29 +/- 0.05 dB/cm/MHz in hepatic hemangioma, 0.43 +/- 0.05 dB/cm/MHz in HCC, and 0.41 +/- 0.12 dB/cm/MHz in metastatic liver tumor. Hepatic adenoma and focal nodular hyperplasia of the liver produced higher values, averaging 0.66 +/- 0.09 dB/cm/MHz. This difference between malignant and benign tumors was statistically significant. There was some correlation between the FDA for the hepatic tumor and the histopathology that merits further investigation.

Adenoma↗
PubMedDate not supplied

cDNA cloning of a mandibular organ inhibiting hormone from the spider crab Libinia emarginata.

Mandibular organs (MO) produce a crustacean juvenile hormone, methyl farnesoate (MF). MO activity is negatively regulated by factors, called mandibular organ inhibiting hormones (MOIHs), from the crustacean sinus gland X-organ complex in the eyestalks. Three MOIHs have been isolated previously from the spider crab Libinia emarginata and are characterized as members of the crustacean hyperglycemic hormone (CHH) neuropeptide family. In the research reported here, a full length cDNA sequence of 972 bp of a MOIH was isolated by screening a cDNA library constructed from the eyestalks of Libinia emarginata. This cDNA sequence encodes a preprohormone peptide with 137 amino acid residues, including a 26-amino acid long signal peptide, a 34-amino acid long precursor peptide, a dibasic peptide, the full length of 72-amino acid long MOIH, and a tri-peptide Gly-Lys-Lys which designates the potential amidation site at the C-terminus of the mature peptide.

Amino Acid Sequence↗
PubMedDate not supplied

Age-related impairment of long-term depression in area CA1 and dentate gyrus of rat hippocampus following developmental lead exposure in vitro.

Chronic developmental lead exposure is known to be associated with cognitive dysfunction in children. Impairment of the induction of long-term depression (LTD) has been reported in area CA1 and dentate gyrus (DG) of rat hippocampus following chronic lead exposure. The present study was carried out to investigate age-related alterations of LTD in area CA1 and DG of rat hippocampus following developmental lead exposure in vitro. Neonatal Wistar rats were exposed to lead from parturition to weaning via milk of dams drinking 0.2% lead acetate solution. Field excitatory postsynaptic potentials (EPSPs) were recorded in hippocampal slices at various postnatal ages: postnatal day (PND) 17-23, 27-33, and 57-63. Following low-frequency stimulation (LFS, 900 pulses/1 Hz), the average magnitude of LTD is age related. In the controls, LTD magnitude in area CA1 decreased with age, whereas in DG it increased with age. In the lead-exposed groups, the magnitude of LTD declined during development in both area CA1 and DG. The differences of LTD magnitude between the control and lead-exposed rats were 27.26 +/- 9.15% (PND 17-23), 21.59 +/- 12.93% (PND 27-33), and 16.96 +/- 9.33% (PND 57-63) in area CA1, and were 6.95 +/- 9.26%, 17.60 +/- 3.91%, and 33.63 +/- 10.47% in DG, respectively. These results demonstrated that the lead-induced impairment of LTD magnitude was an age-related decline in area CA1 and an age-related increase in area DG of rat hippocampus. Published by Elsevier Science Inc.

Aging↗
PubMedDate not supplied

Expression of a mutant opsin gene increases the susceptibility of the retina to light damage.

The question of whether the expression of mutant opsin predisposes the retina to light damage was addressed using transgenic mice that express rhodopsin with three point mutations near the N-terminus of the molecule. The mutations involve the substitution of histidine for proline at position 23 (P23H), glycine for valine at position 20 (V20G), and leucine for proline at position 27 (P27L). These mice express equal amounts of mutant and wild-type transcripts, and develop a progressive photoreceptor degeneration that is similar to that seen in human retinitis pigmentosa (RP). The P23H mutation is associated with the most frequently occurring form of human autosomal dominant retinitis pigmentosa (ADRP) in the United States. Transgenic and normal littermates were exposed to illuminance of 300 foot-candles (ft-c) for 24 h, then placed in darkness for either 6 h, 6 days, or 14 days. Histological and biochemical techniques were used to evaluate the outer retina in light-exposed and control animals reared on 12-h light/12-h dark cycle. The results indicate that light exposure accelerates the pathological changes associated with the transgene expression. Compared with transgenic animals reared in ambient cyclic light, retinas from light-exposed mice had a reduced rhodopsin content, fewer photoreceptor cell bodies, and less preservation of retinal structure. Data obtained from normal mice did not differ for the lighting regimens used. These findings suggest that the expression of VPP mutations in the opsin gene predisposes the transgenic photoreceptors to be more susceptible to light damage. The data also suggest that reducing photic exposure may be beneficial to any patient with RP mediated by an opsin mutation.

Animals↗
PubMedDate not supplied

In vivo transchelation of copper-64 from TETA-octreotide to superoxide dismutase in rat liver.

An understanding of the metabolic fate of radiometal-labeled peptides is important due to their application in the areas of diagnostic imaging and targeted radiotherapy. Radioisotopes of copper ((64)Cu, T(1/2) = 12.7 h; (67)Cu, T(1/2) = 62 h) have been labeled to monoclonal antibodies (mAbs) and peptides and have applications in the areas of PET imaging and targeted radiotherapy of cancer. Copper-64-TETA-D-Phe(1)-octreotide ([(64)Cu]TETA-OC) has been shown to bind to the somatostatin receptor, both in vitro and in vivo, and this agent inhibited the growth of somatostatin-receptor positive tumors in rats. Copper-64-TETA-OC, however, showed a retention of activity in the blood, liver, and bone marrow, suggesting possible dissociation of (64)Cu from TETA-OC in vivo. The purpose of this study was to determine if (64)Cu dissociates from [(64)Cu]TETA-OC and binds to the protein, superoxide dismutase (SOD) in rat liver. The liver metabolism of [(64)Cu]TETA-OC was examined in normal rats using a gel-electrophoresis assay specific for SOD and size-exclusion chromatography. The major metabolite in rat liver at 20 h postinjection had a molecular weight of 32 kDa as shown by size-exclusion chromatography. A gel electrophoresis assay specific for the detection of SOD [nitro-blue tetrazolium (NBT)] showed that a (64)Cu-labeled protein isolated from rat liver homogenates comigrated with SOD. Evaluating the metabolic fate of copper radiopharmaceuticals demonstrated that Cu(II) dissociates from macrocyclic chelators such as TETA and binds to proteins in high concentrations, namely SOD in rat liver.

Animals↗