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Biomedical subjects

Z Liu

Publications and source records attributed to Z Liu.

At least 1,189 records · Page 66Linked to original sources
PubMed1994

Controlled evaluation of copper-silver ionization in eradicating Legionella pneumophila from a hospital water distribution system.

A controlled evaluation was made of the efficacy of copper-silver ionization in eradicating Legionella pneumophila from a hospital water supply. Copper-silver ionization units were installed on the hot water recirculation line of one building with water fixtures positive for Legionella species. Another building with the same water supply served as a control. Legionella species persisted within the system when copper and silver concentrations were < 0.3 and < 0.03 ppm, respectively. When copper and silver concentrations were > 0.4 and > 0.04 ppm, respectively, there was a significant decrease in Legionella species colonization, but the percentage of water fixtures positive for organisms was unchanged in the control building. When the ionization unit was inactivated, water fixtures continued to be free of Legionella species for 2 additional months. Copper-silver ionization can eradicate L. pneumophila in a water distribution system. The advantages of copper-silver ionization include relatively low cost, straightforward installation, easy maintenance, nontoxic by-products and the presence of a disinfecting residual.

Copper↗
PubMed1994

A longitudinal study of cytomegalovirus infection in human immunodeficiency virus type 1-seropositive homosexual men: molecular epidemiology and association with disease progression.

Cytomegalovirus (CMV) isolates from 234 asymptomatic human immunodeficiency type 1 (HIV-1)-positive men were analyzed for molecular relatedness using junctional hybridization. Of isolates shed simultaneously at two or more body sites, 36% from 22 men were different. Of 180 isolates collected from 67 men over 15 months, different strains were isolated serially from 27 men (40%), most from semen. After follow-up of 58 months (mean), the relative hazard of HIV infection progressing to AIDS was 1.8 (95% confidence interval [CI], 0.9-3.7) for men shedding the same strain of CMV and 3.0 (95% CI, 1.4-6.1) for men shedding different strains compared with men not shedding CMV in semen. The prevalence of CMV-specific IgM was higher in men shedding different versus same CMV strains (32% vs. 18%; P = .244). Thus, presence of multiple CMV strains in HIV-1-positive homosexual men is associated with progression to AIDS, possibly via activation of HIV-1-infected CD4 cells.

Cohort Studies↗
PubMed1994

Towards understanding the limits of distortion product otoacoustic emission measurements.

Distortion product otoacoustic emission (DPOAE) data were obtained with a custom-designed system from 20 subjects with normal hearing. Cavity measurements, using this system and an Etymotic ER-10B low-noise microphone system, resulted in estimates of recording system distortion of -20 dB SPL for f2 frequencies ranging from 500 to 8000 Hz, and primary levels ranging from 20 to 75 dB SPL (L2 = L1-10 dB). Using this system it was possible to automatically adjust averaging time in order to obtain the same residual noise levels across frequencies. In all subjects with normal hearing, DPOAEs were measurable over a wide range of primary levels for octave f2 frequencies from 1000 to 8000 Hz, but not at 500 Hz. At 500 Hz, only half of the normal-hearing subjects produced DPOAEs that were above the noise floor. When they did, DPOAE amplitude was less than that observed at higher f2 frequencies. While the cause for response absence in some normal ears may have been due to residual noise, the reduced amplitude suggests that the other factors influence the measurement of DPOAEs at low frequencies. This result may be due to reduced cochlear production of DPOAEs at lower frequencies or reduced transmission through the middle ear.

Acoustic Stimulation↗
PubMed1994

31P-MRS measurements of extracellular pH of tumors using 3-aminopropylphosphonate.

The extracellular pH (pHex) of tumors is generally acidic. However, it is only recently that noninvasive magnetic resonance spectroscopic (MRS) measurements have determined that the intracellular pH (pHin) of tumor cells in situ is neutral or slightly alkaline compared with that of normal tissues. Thus cells in tumors maintain larger pH gradients than do cells in nontumor tissues. To date, measurements of pHex in tumors have been made using microelectrodes, which preclude measurement of pHex and pHin within the same preparation. In addition, microelectrodes are invasive and have the potential to alter the measured pH values. The present communication describes simultaneous measurement of pHex and pHin in vitro in bioreactor culture and in vivo using 31P-MRS analyses of 3-aminopropylphosphonate (3-APP) and inorganic phosphate. In vitro results indicate that 3-APP is not toxic and that its resonant frequency is sensitive to pH and not significantly affected by temperature or ionic strength. Bioreactor experiments indicate that this compound is neither internalized nor metabolized by cells. Experiments in vivo indicate that 3-APP can be administered intraperitoneally and that RIF-1 tumors maintain a steady-state pHin of 7.25 and a pHex of 6.66. These data have significance to basic tumor cell physiology and to the design of approaches to cancer chemotherapy and hyperthermic therapy, because both of these modalities exhibit pH sensitivity. It is also likely that these techniques will be applicable to localized MRS of other organ systems in vivo.

Animals↗
PubMed1994

Localization of the highly polymorphic locus D19S120 to 19p13.3 by linkage.

To obtain the regional localization of a dinucleotide repeat D19S120 (formerly designated LIPE) with 7 alleles and an observed heterozygosity of 73% (Levitt et al., 1992) we typed 40 CEPH families. Given the high heterozygosity and ease of typing, this marker represents a useful addition to the index map of chromosome 19.

Animals↗
PubMed1994

Autoimmune response against the bullous pemphigoid 180 autoantigen.

An immunodominant and potentially pathogenic epitope associated with bullous pemphigoid (BP) and herpes gestationis (HG) has recently been mapped by our laboratory to a noncollagenous stretch of the extracellular domain of the human BP180 antigen. This antigenic site, designated the MCW-1 epitope, has been shown to be recognized by the majority of BP and HG sera. Interestingly, the MCW-1 epitope is absent from the murine BP180 molecule, and therefore, human autoantibodies directed against this site could not be tested for pathogenicity using the conventional passive transfer mouse model. Alternatively, rabbit antibodies were prepared against recombinant forms of the human MCW-1 epitope and the murine NC16A domain and were tested for pathogenicity by passive transfer experiments. Neonatal mice injected with rabbit antimurine BP180 IgG developed a subepidermal blistering disease that closely mimicked BP and HG at the clinical, histological and immunological levels. Rabbit IgG specific for the human MCW-1 epitope was not pathogenic. These results suggest that the autoantibodies against the MCW-1 epitope of the human BP180 antigen found in BP and HG sera may be relevant in the pathogenesis of blister formation in these patients.

Animals↗
PubMed1994

Experimental revascularization of airway segments.

A series of experiments was conducted to assess the possibility of revascularizing tracheal autografts with the rabbit lateral thoracic fascial flap. Injection studies and histological evaluation displayed optimal revascularization and reepithelialization of the graft after 2 weeks.

Animals↗
PubMed1994

Embryonic adenosine triphosphate:phosphodiesters ratios obtained with in vivo nuclear magnetic resonance spectroscopy (phosphorus-31): a new technique for selecting leaner broiler chickens.

Phosphorus-containing compounds of 18-d-old embryos from two broiler chicken lines, differing in body fat content, were measured using in vivo 31P nuclear magnetic resonance (NMR) spectroscopy. Subsequently, the same birds were slaughtered at 8 wk of age and the whole body was analyzed for body fat content. The birds of the fat line had lower (P = .002) embryonic adenosine triphosphate (ATP):phosphodiester (PDE) ratios, higher (P = .002) body fat content when adjusted to common BW, and higher (P = .047) dry matter content than the lean line. No differences (P > .05) were detected for BW between the two lines. Females of the two lines had lower (P = .002) ATP:PDE ratios, lower (P = .001) BW, higher (P = .003) adjusted fat contents, and higher (P = .003) dry matter content than the males. No interaction (P > .05) between sexes and lines was detected for any variables. Regression equations indicating a linear negative relationship (Ybody fat content = 369.05 - 407.27 XATP:PDE + .1295 XBW, R2 = .62 to .78; or Ybody fat % = 30.57 - 19.4 XATP:PDE, R2 = .49 to .71) between embryonic ATP:PDE ratios and body fat content were developed.

Adenosine Triphosphate↗
PubMed1994

[Regulative effects of electroacupuncture on gastric hyperfunction induced by electrostimulation of the lateral hypothalamus area of rabbits].

This paper reported our observation of the action of acupuncture on the change of gastric function induced by the excitation of the lateral hypothalamus area (LHA, the feeding center), and research on the mechanism of the acupuncture to inhibiting excessive appetite and reducing hunger in obese people. Electroacupuncture at Zusanli (ST 36) or Neiting (ST 44) could inhibit the hyperactivity of the stomach induced by stimulation of LHA (P < 0.05, P < 0.01). The electroacupuncture effect on LHA remained statistically significant (P < 0.05, P < 0.01) 0.5-2.5 hours after acupuncturing. The alpha-receptor blocking agent phentolamine (1mg/kg) was not distinctly affected (P > 0.05) on the inhibition of electroacupuncturing Zusanli (ST 36) to restrain the hyperactivity of the stomach induced by stimulation on LHA; But beta-receptor blocking agent propranolol (0.3mg/kg) could obviously inhibit the effect of electroacupuncturing Zusanli (ST 36) to restrain hyperactivity of stomach triggered by excitation of the LHA. The result shows that electroacupuncture obviously inhibits gastric hyperfunction caused by excitation of the LHA, for as long as over 3 hours, thus indicating the participation of the humoral factors. Since the electroacupuncture at Zusanli (ST 36) only inhibits gastric hyperfunction caused by excitation of the LHA, it is suggested that the electroacupuncture has an anticholinergic effect through the gastric beta receptor, therefore it inhibits the appetite, relieves hunger and reduces body weight in obese people.

Animals↗
PubMed1994

[Further study on the essence of acupoint specialty in mice].

Trace element, Cr+3 or V+5 are injected into acupoint of mice for pretreatment and then pentobarbital sodium injected into the same points, it is found that the element Cr+3 may shorten time of onset sleeping and prolong time of maintenance sleeping of injecting pentobarbital sodium at "Zusanli" point, while the element V+5 may shorten time of onset sleeping and prolong time of maintenance sleeping of injecting pentobarbital sodium at "Neigran" point. It indicates different trace elements can produce different influence on acupoint drug effect entering "Zusanli" or "Neiguan" point. The results mentioned above suggest that the different responses of different acupoints to same drug may be related to the different ion structures or different semi-conductive properties of the different acupoints.

Acupuncture Points↗
PubMed1994

Studies on high concentration ethanol fermentation of raw ground corn by Saccharomyces sp. H0.

In this study, high concentration alcoholic fermentation coordinated with saccharification from raw ground corn was performed at 30 degrees C, pH 4-5, in batch culture using Saccharomyces sp. H0 which was constructed by hybridization in this laboratory and the glucoamylase preparation produced on a large scale in China. The optimal conditions for high concentration ethanol production were that the amount of the glucoamylase preparation was 300 u/g of raw ground corn, the inoculum size of the yeast was 2.7 x 10(6) cells/ml, the fermentation temperature was 30 degrees C, the starting concentration of raw ground corn was 33.0% (w/v), and the fermentation period was 70 hr. At the end of fermentation, 17.5% (v/v) ethanol was yielded, with 0.19% reducing sugar, 3.5% total sugar and 16.0% cell viability remaining in the fermented mash. In the case of 36.0% (w/v) of the initial raw ground corn concentration, the strain could produce 18.0% (v/v) ethanol, leaving 0.81% reducing sugar and 5.1% total sugar in the media. We found that the glucoamylase preparation which is usually employed for saccharification of cooked starch could be used for efficient saccharification of raw ground corn starch.

Edible Grain↗