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Biomedical subjects

C Wang

Publications and source records attributed to C Wang.

At least 1,459 records · Page 81Linked to original sources
PubMedDate not supplied

Controlled release from a composite silicone/hydrogel membrane.

To enhance the drug uptake and release capacity of silicone rubber (SR), N-isopropylacrylamide (NIPA) hydrogel particles have been incorporated into a SR membrane. The NIPA particles were thoroughly blended with uncured SR with a certain ratio at room temperature. The mixture was then cast in a Petri dish to 1 mm thickness and cured 10 hours at 90 degrees C. The SR/NIPA composite gel can absorb water approximately equal to its dry weight. Brilliant blue, used as a mock drug, was loaded into the composite gel. Drug release increased exponentially to a final value that is temperature dependent: low at T> =34 degrees C, and high at T< 34 degrees C. This finding is because the hydrophobicity of NIPA changes with temperature. Pulsed release in response to temperature switching between 20 and 39 degrees C has been achieved. Drug uptake and release capability strongly depends upon the structure of the composite gel. The optimal range of NIPA composition is between 75 and 87% by volume. In the cited range, the NIPA particles form an interconnected network that provides a channel for diffusion of drug solution. The SR/NIPA composite gel has promising attributes as a wound dressing and other uses.

Acrylamides↗
PubMedDate not supplied

Spermatozoal fertilizing capacity in polyzoospermia: a preliminary study.

Men with the spermatological symptom of polyzoospermia (greater than 250 X 10(6) sperm/ml) have been reported to seldom impregnate their wives. It was the aim of this study to investigate the spermatozoal fertilizing capacity in polyzoospermia by the human sperm and zona-free hamster ova penetration bioassay. General semen characteristics and in vitro spermatozoal fertilizing capacity were studied in 12 polyzoospermic male partners of couples of infertile marriages. The results were compared with those from a control group of normospermic fertile men (n = 22). No significant differences in sperm motility, normal morphology and in vitro spermatozoal fertilizing capacity were found between the two groups. The polyzoospermic men we studied did not appear to have any defect with the spermatozoal fertilizing capacity, as assessed by the heterologous sperm--ova penetration bioassay. The apparent impairment of fertility and higher abortion rate in couples with polyzoospermic male partners, as described in the literature, may be related to chromosomal aberrations and/or other unknown functional defect of the spermatozoa.

Animals↗
PubMedDate not supplied

The accuracy of sperm concentration determination by the automated CellSoft semen analyzer before and after discontinuous Percoll gradient centrifugation.

The automated CellSoft semen analyzer identifies human spermatozoa on the basis of user-defined values for cell size and luminosity. Previous studies have shown that the non-sperm particles usually present in seminal plasma would interfere with the computerized determination of sperm concentration by the CellSoft system. Therefore, an effective method to separate the sperm from non-sperm particles would be desirable to obtain accurate determination of sperm concentration. In the present study, sperm concentrations in 72 semen samples before and after discontinuous Percoll gradient centrifugation were determined by the automated CellSoft system and the results compared with those obtained with the routine procedure using the haemocytomer according to the World Health Organization laboratory manual. The computerized measurement caused a significant overestimation when the sperm concentration in semen was less than 80 x 10(6)/ml. Processing of human semen sample by the simple two-layer discontinuous Percoll gradient centrifugation removed the majority of non-sperm particles and the overestimation by the automated CellSoft system became significant only when the sperm concentration in the final Percoll sperm preparation was less than 10 x 10(6)/ml. These findings indicate that the automated CellSoft semen analyzer has to be improved to allow for the correction of non-sperm particles in seminal plasma or processed sperm samples before it can be used to provide sufficiently accurate sperm concentration results for routine laboratory service or research purposes.

Cell Separation↗
PubMedDate not supplied

Limits of parallel processing: excitatory convergence of different information channels on single neurons in striate and extrastriate visual cortices.

1. It has been postulated that the distinct parallel retino-geniculo-cortical information channels characterizing visual pathways of virtually all mammals are selectively linked to parallel motion, colour and/or form information processing 'streams' distinguishable within the primary visual cortices, extrastriate cortical areas of occipital lobes and the temporal and parietal visual cortices. 2. Using selective pressure-blocking of the large-fibre channel (the so-called Y-channel) in the optic nerve of the cat, we have experimentally examined the 'selective excitatory parallel links' hypothesis. We conclude that the majority of neurons in the primary visual cortices (areas 17, 18) as well as in the two 'higher order' visual areas, area 21a and posteromedial lateral suprasylvian (PMLS) area, constituting, respectively, part of the 'form' and part of the 'motion' processing streams, receive their excitatory inputs from both Y- and non-Y-information channels. In areas 17, 18 and 21a (but not in PMLS area), there are, however, subpopulations of cells that apparently receive excitatory inputs from only one information channel. 3. Review of the relevant work on the macaque monkey suggests that the situation is similar in the primate: that is, there is a substantial degree of excitatory convergence of different retino-geniculo-cortical information channels on single neurons in the primary visual cortices and the extrastriate cortices constituting parts of the form/colour or the motion processing streams. 4. Despite this high degree of excitatory convergence of different information channels, the large-fibre channels (the Y-channel in the cat and the magnocellular or Y-like channel in macaque), are in both carnivores and primates the principal contributors to the motion processing cortical streams.

Animals↗
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Facilitation of amygdala kindling development and kindled seizures by metaphit.

The effect of metaphit (a phencyclidine analogue with an acylating isothiocyanate) on kindling development and kindled seizures from amygdala was investigated in rats pretreated once with metaphit. Administration of a single dose of metaphit (10 or 20 mg/kg intraperitoneally i.p.) 4 h before the first electrical stimulation of the amygdala did not in itself induce seizures, but greatly facilitated development of behavioral seizures during kindling. This effect persisted throughout the whole process of electrical amygdala kindling without further dosing. In contrast, metaphit only transiently and modestly increased the growth of afterdischarge (AD) duration. In kindled rats, pretreatment with a single dose of metaphit (20 mg/kg) 8 h before the test stimulation reduced the threshold current required to elicit a stage 5 seizure and shortened the latency for bilateral forelimb clonus (BFC) without changing AD duration or BFC duration. The facilitation of kindling development and kindled seizures may be due to an excessive excitatory transmission by metaphit in the limbic seizure circuitry.

Amygdala↗
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Chimeric SHIV that causes CD4+ T cell loss and AIDS in rhesus macaques.

By animal to animal passage in rhesus and pig-tailed macaques, we developed a rhesus model of HIV-1 disease in humans. Rhesus macaques infected with a cell-free stock of SHIVKU-2 developed CD4+ T cell loss, primary lentiviral encephalitis and pneumonia, and AIDS. Six of nine rhesus macaques died within eight months post-inoculation, while the remaining three are at five, five, and eight months post-inoculation, respectively. Animals infected by either mucosal or parenteral routes of infection had a similar course of infection.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Potential use of extensible markup language for radiology reporting: a tutorial.

One of the main goals of radiology is to communicate imaging information to aid in patient management. Information standards can facilitate communication and help realize this goal. Extensible Markup Language (XML) is a new information transmission standard that was developed to meet the growing need for robust, large-scale World Wide Web applications. XML notation provides a compact document representation scheme that allows radiology reports to be transmitted over the Web as universally understandable, self-defining documents. XML documents can include a report-specific document type definition (DTD) that defines the allowable data fields and values. XML may also be used to generate data entry forms for radiology reporting and help physicians improve the efficiency of the reporting process. XML documents can be used to store reporting results directly, thus allowing pertinent data to be shared on the Web. An XML-based approach can allow users to link information to entities outside the information systems of a given institution. XML-based methods and applications have the potential to promote development of robust radiology reporting systems and integration with broader, enterprise-wide information systems.

Databases as Topic↗
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Effects of intraventricular locus coeruleus transplants on seizure severity in genetically epilepsy-prone rats following depletion of brain norepinephrine.

Audiogenic seizures (AGS) in genetically epilepsy-prone rats (GEPR) of the moderate-seizure substrain (GEPR-3s) were investigated to determine whether norepinephrine (NE) depletion induced by 6-hydroxydopamine (6-OHDA) microinfusion into the locus coeruleus (LC) could alter the efficacy of intraventricular NE tissue grafts in promoting reductions in seizure severity in AGS. GEPR-3s were stereotaxically infused with 6-OHDA (4 micrograms/side/rat), or vehicle into the region of the LC. Following 6-OHDA treatment all animals were subjected to 3 AGS tests. GEPR-3s seizure severities were increased in 39.5% of the animals after microinfusion of 6-OHDA into the region of the LC. Following the third AGS test, each rat was stereotaxically implanted with 17 gestational day rat fetal tissue obtained from the dorsal pons and containing the primordia of the LC or with tissue obtained from the neocortex or were sham-grafted. Subsequent to grafting, rats were subjected to 3 additional AGS tests. 53% (10/19) of 6-OHDA treated GEPRs showed a significant reduction in seizure severity following transplantation of fetal LC tissue. In contrast, only 20% (1/5) of GEPRs infused with saline rather than 6-OHDA showed a reduction of seizure severity following fetal LC transplantation. NE content in the cortex and pons/medulla was decreased by 78% and 46% respectively following 6-OHDA microinfusion into the LC. Prominent grafts with numerous TH positive neurons and neurites were present within the third ventricle of grafted animals, while cortex grafts contained no TH immunostained structures. These findings suggest that the efficacy of fetal LC tissue to promote reductions in seizure severity in GEPRs is increased following depletion of central NE by microinfusion of 6-OHDA.

Acoustic Stimulation↗
PubMedDate not supplied

Extract from Arca granosa L. inhibits proliferation of human tumour cell lines with kidney and lung origin.

Marine organisms are being considered increasingly as sources of anti-tumour agents. The extract from Arca granosa L. has been shown to decrease the growth of tumours and this study was undertaken to determine its ability and mechanism of inhibition. The extract inhibited the proliferation of six human tumour cell lines from different origins with varying sensitivity. The cell lines Ketr-3, A549 and NCl-H460 with kidney or lung origins were more sensitive to the extract than those of the HepG-2, MCF-7 and MGC-803 cells from other origins. In the three sensitive cell lines (Ketr-3, A549 and NCI-H460) the extract was shown to block different phases of the cell cycle progression and inhibit DNA synthesis in a concentration-dependent manner. It was concluded that the extract from A. granosa is potentially a novel anti-tumour agent, especially on kidney and lung tumour cell lines.

Animals↗
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An automated tumor resection device for neurological surgery.

A pneumatically activated cutting probe has been designed for the neurosurgical removal of nervous system tumors or diseased tissue. The hand-held probe is formed of concentric slender tubes, one reciprocating inside the other. A scalpel-sharp edge on the tip of the inner tube moves in a shear motion past a stationary port on one side near the distal end of the outer tube. The reciprocating motion of the inner tube is provided by a pneumatic power source housed in a separate control console.

Brain Neoplasms↗
PubMedDate not supplied

Accumulation of rare earth elements in corn after agricultural application.

Using both pot and plot experiments, the dose-dependent accumulation of rare earth elements (REs) in corn (Zea mays L.) after application of an agricultural REs mixture was measured. In the pot experiment, the dose-dependent accumulation of REs in corn root and stem was observed, but it could not be detected in corn leaf under the dosage of 20 mg REs kg(-1) soil (oven-dry mass). The non-observed effect concentration (NOEC) for accumulation of REs in corn seedling with the pot experiment was 1.0 mg REs kg(-1). In the plot experiment, the dose-dependent accumulation was observed at an early stage after application of REs and the NOEC value of 32 mg REs m(-2) was obtained. At harvest, no dose-dependent accumulation of REs was observed in any part of the corn. These results can be confirmed by the fingerprinting analysis based on the differences between La to RE ratios in the REs mixture and in pot or plot soil. We observed that the plant shows no preference on individual RE and the results of fingerprinting indicated clearly the incorporation of exogenous REs in plant tissues, in a similar manner as that observed in the dose-dependent distribution of RE concentrations. The results indicated also a translocation process of REs from plant root to leaf when applied to soil or from leaf to root when applied to leaf. A homeostatic regulation mechanism for excessive uptake of REs in plants is suggested to regulate the concentrations of REs in the plant.

Agriculture↗
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Chondromyxoid fibroma of the nasal septum: a case report emphasizing clinical correlation.

Chondromyxoid fibromas are uncommon tumors most often seen in long bones of adolescent and young males. Involvement of craniofacial bones is extremely unusual, with sporadic case reports described in the literature. We describe the first case of chondromyxoid fibroma arising in the nasal septum with local destruction and expansile growth into the ethmoid bone and inferior turbinate in a 60-year-old female. The fortuitous discovery of this otherwise asymptomatic lesion and its follow-up are detailed. The literature is reviewed and salient clinical, radiographic, and pathologic correlative findings are emphasized.

Chondroblastoma↗
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The important role of international exchange in the development of medical informatics in developing countries: a report from China.

China is a developing country, and so is inferior to the developed countries in many aspects of science and technology. It is similarly a new member in the world ranking of the application of computers in biomedicine. However, since implementing the policy of reform and opening to the outside world in 1976, China has achieved greater success in biomedical signal and image processing, biomedical data processing, computer-aided diagnosis, computerized hospital management, etc. China's development shows that international exchange and cooperation are very important for the development of medical informatics in developing countries, and the application of computers in biomedicine has progressively spread all over the world and is increasingly taking root in the hearts of the people.

China↗
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Clinical significance of p53, MDM2 and bcl-2 expression in transitional cell carcinoma of the bladder.

We investigated the prognostic and predictive relevance of p53, MDM2, and bcl-2 protein expression in patients with transitional cell carcinoma (TCC) of the bladder. The expression of p53, MDM2 and bcl-2 protein was studied by immunohistochemical methods in paraffin-embedded specimens from 119 patients whose clinicopathologic data confirmed TCC of the bladder. Multivariate analyses of prognostic factors were performed, and correlations with classical clinicopathologic parameters were examined. Sixty-one, 12, and 17% of cases were considered positive for expression of p53, MDM2 and bcl-2, respectively. p53 expression correlated with stage (p=0.0209), but not MDM2 and bcl-2 with any clinicopathologic parameters. In Cox's regression analysis, staging demonstrated a statistically worse prognosis (hazard ratio 1.636; p=0.0059) while bcl-2 (hazard ratio 0.179; p=0.0474) expression showed favorable prognosis in stage T2-4 invasive TCC of the bladder. Co-expression with p53/MDM2 (hazard ratio 0.367; p=0.0401) and p53/bcl-2 (hazard ratio 3.487; p=0.0111) overexpression were associated with favorable and unfavorable prognosis in stage T2-4 invasive TCC of the bladder, respectively. Our results indicate that staging is the most useful parameter to predict clinical outcome in patients with TCC of the bladder. Determinations of bcl-2 and co-expression p53/MDM2 and p53/bcl-2 may be useful for predicting tumor behavior and prognosis in stage T2-4 invasive type TCC of the bladder.

Adult↗
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The case of the hidden harassment.

The past year has seen a growing public awareness of sexual harassment in the workplace. The question of what constitutes sexual harassment and how to recognize it has been debated in the news, the courts, and Congress. This HBR case study is less concerned with defining it than with examining what a manager should do about it. When Filmore Trust manager Jerry Tarkwell found out one of his employees was being sexually harassed on the job, he thought he knew exactly what to do. Following company policy, he immediately notified the bank's equal employment office. Then he called Jill McNair, the employee being harassed. Her response dumbfounded him. "You had no right to call EEO before talking to me," McNair said angrily. Do you have any idea what could happen to me and to my career if people find out about this?" Tarkwell didn't understand; McNair wasn't to blame. He believed the only person who should be worried was the harasser. Tarkwell tried to spell out the procedure for her. "All you have to do is write a letter and ..." McNair cut him off. "If this gets investigated by EEO, everyone in the building could be questioned. I'll probably get transferred, and then I won't have a chance at promotion. And who'd want to work with me? Every man in the company would be afraid I'd report him if he so much as opened a door for me."(ABSTRACT TRUNCATED AT 250 WORDS)

Confidentiality↗
PubMedDate not supplied

Reproductive aging in the Brown Norway rat is characterized by accelerated germ cell apoptosis and is not altered by luteinizing hormone replacement.

Reproductive aging in the male Brown Norway (BN) rat is characterized by decreased Leydig cell steroidogenesis associated with seminiferous tubule dysfunction. This could be a result of a combination of a primary testicular defect and a secondary hypothalamic pituitary dysfunction. In the present study, we determined in the BN rat whether germ cell loss occurred via apoptosis. We then defined the age of onset of Leydig cell dysfunction and germ cell loss and examined whether chronic luteinizing hormone (LH) replacement would delay or prevent reproductive aging. Plasma hormone levels, testicular sperm concentrations, and germ cell apoptosis were studied in 6, 9, 12, 15, 18, and 21-month-old BN rats. Beginning at 15 months, testicular weight, sperm concentration, total sperm counts, plasma testosterone, LH, and inhibin decreased, whereas the proportion of regressed testes and plasma follicle-stimulating hormone (FSH) levels increased with aging. Accelerated germ cell apoptosis involving spermatogonia, preleptotene and pachytene spermatocytes, and spermatids was evident in some tubules of the relatively normal testes from 21-month-old rats. In the regressed testes, complete cessation of spermatogenesis occurred. The apoptotic index was higher in the testes of old (21-month-old) rats in particular at stages XII-XIV when compared with younger animals. Chronic LH replacement (0.5 microg i.p. twice per day) administered to 15-month-old BN rats for 6 months did not alter plasma hormone levels, testes weight, sperm concentration or content, or the germ cell apoptotic index. In the control group, 3 out of 10 testes were regressed, whereas in the LH-replaced group, only 1 out of 12 testes was regressed. We show in this study that early reproductive aging in the BN rat began at around 15 months. Germ cell loss associated with aging occurs via apoptosis. Replacement therapy with LH for 6 months does not decrease or delay the testicular dysfunction associated with aging. It is unlikely that hypothalamic-pituitary dysregulation is the major cause of testicular aging.

Aging↗
PubMedDate not supplied

Comparison of the immunofluorescent assay and reverse transcription-polymerase chain reaction to detect and type infectious bronchitis virus.

Indirect fluorescent antibody (IFA) assay and reverse transcription-polymerase chain reaction (RT-PCR) are two current methods commonly used for the detection of infectious bronchitis virus (IBV) and its serotypes. The objectives of this study were to compare the two methods relative to detecting IBV in chicken embryos that were artificially inoculated with Mass41, Ark99, or Mass41/Ark99 in serial embryo passages and in tracheas and cecal tonsils collected from vaccinated commercial flocks with and without respiratory problems. The tissues collected from these birds were used to inoculate chicken embryos. The chorioallantoic membranes collected from the inoculated embryos were examined by the IFA assay, and the allantoic fluids collected from the same embryos were subjected to the RT-PCR. The IFA assay and RT-PCR both were able to detect and type IBV when only one IBV strain was inoculated into embryos, regardless of the number of passages. When embryos were inoculated with Mass41 and Ark99 strains simultaneously, both strains were 100% detected by the RT-PCR. By the IFA assay, 20% of samples were positive for two strains and 80% were positive for the Ark only. Two of eight samples collected from healthy flocks that were vaccinated with Mass/Conn/Ark were positive by the IFA assay, and four of eight were positive by the RT-PCR. Sixteen percent (12/75) of the samples from birds experiencing respiratory problems were positive by the IFA assay and 35% (26/75) were positive by the RT-PCR. Results suggest that the RT-PCR is more sensitive than the IFA assay, especially when more than one strain of IBV is involved, but the IFA assay is rapid and cheaper than the RT-PCR.

Animals↗