Search PubMed⌕ Search

Biomedical subjects

L Zhou

Publications and source records attributed to L Zhou.

At least 631 records · Page 35Linked to original sources
PubMed1984

Electric acupuncture stimulates non-parietal cell secretion of the stomach in dog.

Effects of acupuncture and electroacupuncture (EAP) on gastric secretion were studied in the interdigestive state of five conscious dogs prepared with esophagostomy and gastric cannulas. Both EAP and acupuncture without electrical stimulation produced significant increases in gastric secretion of bicarbonate and sodium. At the same time, a marked decrease in gastric secretion of acid was noted. EAP clearly demonstrated a greater effect on gastric secretion within these three parameters than did simple acupuncture. The fact that the effects of EAP and acupuncture on gastric secretion of bicarbonate and sodium were completely blocked by either a local anesthetic agent or anticholinergic agent indicates that gastric secretion involves a somatic afferent-visceral reflex mechanism in which a cholinergic nerve plays a role.

Acupuncture Therapy↗
PubMedDate not supplied

Removal of endotoxin from aqueous solutions by affinity membrane.

Endotoxin was removed by affinity membranes with histidine immobilized as affinity ligand. Macropore cellulose membrane was prepared from filter paper by alkaline treatment and chemical crosslinking, and was used as matrix for the immobilization of affinity ligand. The matrix membrane was derived by hexamethylenediamine and activated by glutaraldehyde before histidine was immobilized. Membrane cartridges containing 40 or 80 sheets of affinity membrane were also prepared, which can be used to remove pyrogen from aqueous solutions. Using a cartridge with 40 sheets of affinity membrane, the endotoxin content in solution can be reduced to a minimum of 0.12 EU/mL.

Chromatography, Affinity↗
PubMedDate not supplied

Membrane affinity chromatography used for the separation of trypsin inhibitor.

Polysulphone (PS) was chemically modified by acrylation-amination and by chloromethylation-amination, respectively. An ultrafiltration membrane of chemically modified polysulphone (CMPS) was prepared by the phase inversion method. Trypsin was then covalently bonded onto the CMPS membrane by diazotization. The activity of immobilized trypsin reaches up to 10200 U/g; 15 mg trypsin was immobilized on 1 g CMPS membrane. Separation of soybean trypsin inhibitor was carried out on the affinity membrane, yielding 6.5 mg pure trypsin inhibitor in one run. The enzyme membrane has good activity and stability.

Chromatography, Affinity↗
PubMedDate not supplied

A new matrix for affinity chromatography and its application in the separation of a human monoclonal antibody.

A method for the preparation of a p-aminobenzene sulphonyl ethyl containing crosslinked Sepharose 4B (ABSE-Sepharose 4B-CL) is described, trypsin, bovine serum albumin (BSA) and concanavalin A (Con A) were immobilized onto this matrix by diazotization. Conditions for the coupling reaction were investigated. The activity of immobilized trypsin reached 1.4 x 10(4) U/g, and 25 mg BSA can be coupled onto 1 g ABSE-Sepharose 4B-CL under the optimal conditions. An affinity medium with immobilized Con A as ligand was prepared by this method, and was used in the separation of a human monoclonal antibody.

Antibodies, Monoclonal↗
PubMedDate not supplied

Similarities and differences among inner retinal neurons revealed by the expression of reporter transgenes controlled by Brn-3a, Brn-3b, and Brn-3c promotor sequences.

Brn-3a, Brn-3b, and Brn-3c are highly homologous POU-domain transcription factors that are expressed in subsets of retinal ganglion cells. From each of the mouse Brn-3 genes, a DNA segment ranging in size from 4.6 to 13.4 kb and located immediately upstream of the start site of translation was joined to a human placental alkaline phosphatase (AP) reporter cDNA. Following the introduction of each construct into the mouse germline, a total of 19 transgenic lines were obtained, of which 16 expressed the AP reporter in the retina. Unexpectedly, at least 14 of the 16 expressing lines showed AP activity in subsets of amacrine cells, and these subsets typically differed among mouse lines injected with the same construct. Transgene expression was also found in ganglion cells in four lines and bipolar cells in seven lines. In all cases AP activity was confined to cells in the inner nuclear layer and the ganglion cell layer. The expression of Brn-3 transgenes in multiple cell types in the inner retina is reminiscent of earlier experiments in which visual pigment transgenes were found to be expressed in multiple cell types in the outer retina. Taken together, these observations suggest that anatomically and/or functionally related retinal neurons contain partially overlapping transcriptional regulatory specificities.

Alkaline Phosphatase↗
PubMedDate not supplied

Double-stranded cyclic oligonucleotides with non-nucleotide bridges.

A series of double-stranded, cyclic oligodeoxynucleotides with non-nucleotide bridges have been synthesized, and their physicochemical properties and susceptibility to enzymes have been investigated. These bridged duplexes are of potential interest for their binding properties to transcription factors and other DNA-binding proteins. Triethylene glycol has been employed as the bridge to alter the lipophilicity of the duplex and avoid the potential for enzymatic cleavage. The synthetic route involved the synthesis of a 3'-phosphorylated, nicked double-stranded precursor with the final internucleotide bond being formed chemically using a water soluble carbodiimide. These bridged duplexes have high thermal dissociation temperatures, and the Tm for a triethylene-bridged 20 base pair duplex was higher than that for the corresponding pentathymidylate-bridged duplex. EcoR I endonuclease cleaved a ligated, bridged duplex at a slower rate than the corresponding unmodified duplex, whereas the unligated, bridged duplex was cleaved more rapidly. Sufficient amounts of the bridged octamer and dodecamer were prepared for proton NMR spectroscopic studies, and 2D COSY and NOESY spectra were obtained. The results indicate that the ligated duplex has a B-form conformation.

Base Sequence↗
PubMedDate not supplied

Proteomic analysis of human tears: defensin expression after ocular surface surgery.

Human tear protein profiles were monitored by surface enhanced laser desorption/ionization-time-of-flight mass spectrometry ProteinChip technology (SELDI-TOF ProteinChip) and liquid chromatography-mass spectrometry (LC-MS). Tears were collected from 21 patients scheduled for surgery to remove an ocular surface neoplasm prior to surgery (day 0) and on days 1, 3, and 30 postoperatively. Using this proteomic approach, we verified that three human alpha-defensins (HNP-1, HNP-2, and HNP-3) were significantly up-regulated in their expression after surgery and that their levels decreased to approximately normal by day 30 by which time healing was complete. Further confirmation of the identity of the alpha-defensins in human tears was made by LC purification, trypsin digestion, and ESI-MS/MS analysis of their tryptic digests. The concentrations of HNP-1 and HNP-2 were determined and shown to be markedly increased after ocular surface surgery. The results of the study suggest that human alpha-defensins HNP-1, HNP-2, and HNP-3 are up-regulated after surgery, and may in addition to their antimicrobial properties have an important role in wound healing.

Amino Acid Sequence↗
PubMedDate not supplied

The covalent binding of [14C]acetaminophen to mouse hepatic microsomal proteins: the specific binding to calreticulin and the two forms of the thiol:protein disulfide oxidoreductases.

Numerous in vitro studies have indicated that acetaminophen is activated by mouse hepatic microsomal cytochrome P450 to form N-acetylbenzoquinone imine. This in turn covalently binds through a Michael addition to protein sulfhydryl and amino groups. Although acetaminophen adducts of several cytosolic proteins have been purified after its administration in vivo, no adducts of specific microsomal proteins have been reported. We find that, after the in vitro incubation of mouse hepatic microsomes with [ring-14C] acetaminophen in the presence of an NADPH generating system, 95% of the bound radioactivity was associated with adducts to three intraluminal microsomal proteins: calreticulin and the two forms of thiol:protein disulfide oxidoreductase, Q2 and Q5. The acetaminophen bound to 0.35, 1.32, and 0.25 mol/mol of the three proteins, respectively. Sequencing of the 14C-labeled tryptic peptides indicated that the acetaminophen bound to lysine 103 of Q2, lysines 202, 209 or 210 and 354 of Q5 and lysines 233 or 239 of calreticulin. No adducts of cysteine residues were observed. Our data might suggest that acetaminophen hepatotoxicity results from the formation of the reactive metabolite within the endoplasmic reticulum. This then binds to these essential proteins and blocks the posttranslational modification of secretory and membrane proteins. This inhibition could then lead to cellular injury and death.

Acetaminophen↗
PubMedDate not supplied

Myelinating Schwann cells determine the internodal localization of Kv1.1, Kv1.2, Kvbeta2, and Caspr.

We examined the localization of Caspr and the K(+) channels Kv1.1 and Kv1.2, all of which are intrinsic membrane proteins of myelinated axons in the PNS. Caspr is localized to the paranode; Kv1. 1, Kv1.2 and their beta2 subunit are localized to the juxtaparanode. Throughout the internodal region, a strand of Caspr staining is flanked by a double strand of Kv1.1/Kv1.2/Kvbeta2 staining. This tripartite strand apposes the inner mesaxon of the myelin sheath, and forms a circumferential ring that apposes the innermost aspect of Schmidt-Lanterman incisures. The localization of Caspr and Kv1.2 are not disrupted in mice with null mutations of the myelin associated glycoprotein, connexin32, or Kv1.1 genes. At all of these locations, Caspr and Kv1.1/Kv1.2/Kvbeta2 define distinct but interrelated domains of the axonal membrane that appear to be organized by the myelin sheath.

Animals↗
PubMedDate not supplied

Analysis of potassium channel functions in mammalian axons by gene knockouts.

Mammalian axons express a rich repertoire of various K channel subtypes whose distribution is profoundly affected by myelination. In the past two decades, functional analysis of axonal K channels has been approached primarily through pharmacology. Recently, gene knockout techniques have been used to specifically delete a particular K channel subtype from axons. This is significant since the bulk of K channels in a myelinated nerve are covered by the myelin, making functional analysis of specific K channel subtypes by traditional means difficult. This review summarizes the first mutational analysis of this sort performed on an axonal fast K channel termed Kv1.1. This K channel is concealed by the myelin loops in the paranodes of all major myelinated fiber tracts, and exhibits highly heterogeneous distribution even in certain non-myelinated CNS axons. Physiological analysis of Kv1.1 null mutants suggest novel functions for this axonal K channel subtype, including modulation of conduction failures at branch points and stabilization of transition zones in myelinated nerves.

Action Potentials↗
PubMedDate not supplied

Effects of air pollution on respiratory health of adults in three Chinese cities.

The authors examined potential associations between air-pollution exposures and respiratory symptoms and illnesses of 4,108 adults who resided in 4 districts of 3 large, distinct Chinese cities. Data on respiratory health outcomes and relevant risk factors for parents and children were obtained via standardized questionnaires in the winter of 1988. (The effects in children were described previously.) The yearly averages of ambient levels of total suspended particles in the 4 districts for the years 1985-1988 differed greatly. The authors constructed logistic-regression models to assess the respiratory health parameters of parents of the children. The results revealed significant and strong effects, by district, on prevalence rates of cough, phlegm, persistent cough and phlegm, and wheeze for both the mothers and the fathers. In addition, the odds ratios increased as ambient total suspended particle concentration increased across the 3 urban districts. Other local within-city risk factors, however, may have confounded the total suspended particles-effects association, especially for asthma prevalence. Findings for adults were similar to those found for their children. A strong adverse effect of active tobacco smoking on the fathers' respiratory health was observed. The children appeared to be more strongly affected by passive smoking exposure received in their homes than their mothers.

Adult↗
PubMedDate not supplied

Composition of Pneumocystis carinii neutral lipids and identification of coenzyme Q10 as the major ubiquinone homolog.

The lipids of purified preparations of Pneumocystis carinii carinii freshly isolated from infected rats were analyzed and compared with those of whole lungs from normal and methylprednisolone-immunosuppressed uninfected rats. In this study, the neutral lipid fraction was examined in detail; the relative concentrations of individual classes making up this fraction were quantified. Of particular interest was the nature of the organism's ubiquinone (coenzyme Q, CoQ) fraction because atovaquone, a hydroxynaphtho-quinone (566C80) analog of ubiquinone, is efficacious in the treatment of P. carinii pneumonia. The ubiquinone concentration in both P. carinii and lung tissues was relatively low compared to that present in rat heart and liver tissues. Two homologs were identified in the organism: CoQ10 was the predominant homolog with lesser amounts of CoQ9 present. In contrast, the lungs of normal and immunosuppressed uninfected rats had CoQ9 and lesser amounts of CoQ8, but no detectable CoQ10. Furthermore, radiolabeled mevalonic acid was incorporated in vitro into the ubiquinone fraction of P. carinii indicating that the organism has the de novo branch of the isoprenoid biosynthetic pathway leading to polyprenyl formation. Hence, it was concluded that CoQ10 (if not both CoQ10 and CoQ9) in P. carinii was not scavenged from the host but was synthesized by the organism. Although lung tissues contained substantial free fatty acids, the organism was enriched in these lipids. The high concentration of free fatty acids and relatively low level of triglycerides in P. carinii suggest that fatty acids may represent major carbon sources for ATP production by the organism.

Animals↗