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H Zhou

Publications and source records attributed to H Zhou.

At least 577 records · Page 32Linked to original sources
PubMed1995

Calcitonin receptor isoforms in mouse and rat osteoclasts.

Calcitonin receptors (CTRs) from several species have recently been cloned and shown to belong to the 7 transmembrane domain class of receptor. We have identified two CTR isoforms in the rat, termed C1a and C1b, identical except for a 37-amino-acid insert in the putative second extracellular domain of C1b. To examine the CTR isoforms expressed in rat and mouse osteoclasts and the time course of their appearance in culture, bone marrow cells were cultured from C57/Bl6J mice and osteoclasts were isolated from newborn rat long bones. CTR-bearing cells were detected by autoradiography of 125I-salmon CT binding, and cultures were stained for tartrate-resistant acid phosphatase (TRAP). RNA was extracted from parallel cultures, and CTR mRNA was detected by Northern blot analysis, using a rat digoxigenin-labeled riboprobe. Characterization of mRNA for the CTR isoforms was by reverse transcription-polymerase chain reaction (RT-PCR) using primer sets and oligonucleotide probes specific for the two rat receptor isoforms. In mouse marrow cultures, TRAP positive mononucleated cells were present by day 2 of culture at which time CTR positive cells were few. Multinucleated cells with both these markers were seen only from day 4 and later. By Northern analysis of total RNA, a band of approximately 4 kb could be detected in day 4 and later cultures. RT-PCR showed that mouse homologs of both C1a and C1b mRNA species were expressed early in cultures of mouse osteoclasts, although at each time C1a appeared to predominate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

rHox: a homeobox gene expressed in osteoblastic cells.

Homeodomain proteins are characterized by a conserved domain with a helix-turn-helix motif. These proteins act as regulatory factors in tissue differentiation and proliferation. However, their role in the regulation of osteoblast differentiation is unknown. In this study we have identified and characterized a homeobox gene in osteoblast-like cells. This gene, termed rHox, was isolated from a cDNA library derived from rat osteoblast-like cells. The nucleotide sequence of the 1,375 base pair (bp) cDNA contains a noncoding leader sequence of 329 bp, a 735 bp open reading frame, and 312 bp of 3' noncoding sequence. Sequence comparison demonstrates that rHox is identical to the mouse Pmx gene (also called MHox) at the amino acid level and 90% homologous at the nucleotide level. Both Southwestern blotting and gel shift analyses indicate that rHox has potential to bind both the collagen I alpha 1 and the osteocalcin promoters. Transfection experiments using an rHox expression vector showed a strong repression of target promoter activity, regardless of whether the target promoters contained homeodomain binding response elements. These data suggest that rHox is a potent negative regulator of gene expression, although the specific role of rHox in bone gene regulation remains to be determined.

3T3 Cells↗
PubMed1995

Vein conduits for repair of nerves with a prolonged gap or in unfavourable conditions: an analysis of three failed cases.

Clinical failure of vein conduits for repair of four nerves in three cases is reported. Two digital nerves with gaps of 5.0 cm and 5.8 cm, respectively, and two median nerves with gaps of 4.0 cm and 5.0 cm were repaired with vein conduits. The digital nerves were repaired secondarily with insertion of nerve tissue slices. The median nerve lacerations were associated with compound soft tissue injuries and were repaired primarily by interfascicular vein conduits. There was no detectable recovery of sensibility in autonomous areas of these nerves and no sign of recovery of the innervated muscles during follow-up. Re-exploration revealed that the vein conduits used for repair of the median nerves were constricted by surrounding scar tissue and axon regeneration was precluded. The critical length for nerve regeneration in human beings and wound conditions unfavorable to nerve regeneration are discussed. This report suggests that vein conduits are not indicated in nerve gaps over 5.0 cm or in primary repair of nerves with compound injuries.

Adolescent↗
PubMed1995

Progressive liver failure in a patient with adult Niemann-Pick disease associated with generalized AL amyloidosis.

We report a case in which an adult form of Niemann-Pick disease (type B of NPD) was associated with a rapidly progressive generalized AL amyloidosis of kappa type. Both diagnosis were made by biopsy, the NPD by bone marrow biopsy and fibroblast culture, the amyloidosis by liver biopsy. Malignant non-Hodgkin lymphoma was not found. The patient, a 67-year-old woman, died from hepatic coma subsequent to a progressive liver failure. We discuss possible relations between the lysosomal storage disease and the development and rapid progression of amyloidosis.

Aged↗
PubMed1995

Immunocytochemical localization of elastase 1 in human pancreas.

By light and electron microscopic immunocytochemistry the distribution is described of human pancreatic elastase 1 (E1) during ontogenesis, in adults, in cases of acute and chronic pancreatitis, acute pancreatic ischaemia as well as pancreatic tumours. E1-positive cells were first detected in ductal sprouts in the 14th gestational week. Complete acini expressing E1 could be found from the 17th to the 20th week of gestation onwards. Scattered distinct E1-positive epithelia could be found in the ducts of fetal and adult pancreas. By immunoelectron microscopy, E1 was localized in rough endoplasmic reticulum, condensing vacuoles, zymogen granules of acinar epithelia and in acinar lumina. E1 appeared to be distributed homogeneously in zymogen granules. As specific markers of acinar cells, both monoclonal antibodies under study identified heterotopic pancreatic acini in peribiliar glands of the liver and also helped to visualize different damage patterns in pancreatitis. The acinar epithelia surrounding acute lipolytic necroses initially reacted more intensely with the E1-antibodies than undamaged pancreatic tissue. In acute ischaemia, acinar cells which are dissociated from intercalated ducts lost their immunocytochemical reactivity for E1. Pancreatic parenchyma involved in advanced acute pancreatitis as well as in chronic inflammation was detected only weakly by both E1-antibodies. However, atrophic lobules in post-inflammatory scars were stained more intensely by the E1-antibodies than normal parenchyma. Pancreatic tumours (adenomas, adenocarcinomas, solid-cystic tumours and islet cell tumours) were not labelled by these antibodies.

Acute Disease↗
PubMed1995

Changes in plasma warfarin levels and variations in steady-state prothrombin times.

OBJECTIVE: To determine the relative contribution of changes in the plasma warfarin level to variation in the serial steady-state prothrombin times. METHODS: This was a prospective observational cohort study performed at two outpatient anticoagulation clinics. Serial prothrombin times and paired plasma total warfarin levels were determined in a convenience sample of otherwise healthy patients who required long-term oral anticoagulation therapy with warfarin. RESULTS: Serial measurements were obtained from 129 patients, 60 of whom provided three or more serial samples. Analysis of covariance showed a highly significant (p = 0.0001) relationship between the anticoagulant effect and the logarithm of the warfarin concentration (R2 = 0.75), with 15.3% of the total variance attributable to the effect of warfarin and 31.1% attributable to individual variation in sensitivity to warfarin. In an analysis of the subjects who had three or more serial measurements, the mean weighted correlation coefficient for the relationship between the logarithm of the warfarin concentration and the anticoagulant response varied widely, from strongly negative to strongly positive, and as the range of observed prothrombin times increased, stronger positive correlation was observed. CONCLUSIONS: In this cohort, the plasma warfarin level was a strong predictor of observed changes in serial prothrombin time measurements. However, the correlation between clotting times and warfarin levels varied widely among subjects, particularly when the range of observed prothrombin times was moderate. This suggests that in these subjects, other factors, such as measurement error or pharmacodynamic changes, played a major role.

Adult↗
PubMed1995

The effects of spatial filtering and contrast reduction on visual search times in good and poor readers.

Recent experiments with reading disabled children have shown that image blurring (produced with frosted acetate overlays) results in an immediate benefit in search performance, eye movement pattern and reading comprehension. This suggests that the contrast and spatial frequency content of visual stimuli are important factors for these children. In the present experiment, spatial frequency filtering and contrast reduction were employed to determine whether either of these factors contributes to the beneficial effects observed. Letter arrays were spatially filtered to produce low pass (< 3.5 c/deg) and high pass (> 7.0 c/deg) images. In addition, a low contrast control image was generated to match the low contrast of the high pass image. Children classified as good reader controls (CON), specific reading disabled (SRD), attention deficit disordered (ADD) or comorbid SRD/ADD (COM) were asked to perform a visual search task with each type of image. With high contrast, unfiltered arrays, the search times for the CON and ADD groups were much shorter than those of the SRD and COM groups. While both high pass and low pass filter conditions improved the search speed for the COM group, improvement for the SRD group was only obtained with low contrast stimuli. These results support the notion that the beneficial results of image blurring with SRDs derives from the contrast reduction produced by such manipulations.

Child↗
PubMed1995

Frontonasal suture expansion in the rabbit using titanium screws.

PURPOSE: This study investigated the ability to use titanium screws to provide stable skeletal points in the growing craniofacial region of the rabbit for suture expansion. These screws provided sites for direct application of external forces to alter growth and anatomic form. MATERIAL AND METHODS: Twenty-one rabbits (30 days old) were divided into three groups: control (n = 9), experimental (n = 9, and sham (n = 3). Four four-holed AO/ASIF commercially pure titanium craniofacial plates were contoured into an L-shape with a 90 degree angle at the midpoint. The plates were placed bilaterally in the frontal and nasal bone sites and secured with 2.0-mm diameter, 4-mm long, commercially pure titanium screws in both the sham and experimental groups. After 4 week of healing, a spring mechanism with a distraction force of 55 g was activated between ipsilateral plates and across the frontonasal sutures bilaterally in the experimental group for 5 weeks. No force was applied between the plates in the sham group. A preliminary evaluation of the bone-implant interface and the changes in the suture was done histologically. Morphologic changes were measured using cephalometric radiographs and direct anatomic measurements. RESULTS: The experimental group showed a significant increase in growth across the frontonasal suture in comparison with the sham group (P < .05). In addition, an increase in the length of the nasal and frontal bones in the expanded group was observed in comparison with the control and sham groups (P < .05). Histologically, a mixture of woven and lamellar bone was seen in the suture region and lamellar bone was seen in the screw-bone interface. CONCLUSION: This study indicates that titanium screws in the developing rabbit skull can provide stable sites for the direct application of external forces, producing secondary changes in skeletal morphology. This laboratory models provides a useful system for the further study of growth modification using such external mechanical forces.

Animals↗
PubMed1995

Enantioselective inhibition of the epidermal growth factor receptor tyrosine kinase by 4-(alpha-phenethylamino)quinazolines.

4-Benzylaminoquinazolines can be potent reversible inhibitors of the EGFR tyrosine kinase at the ATP binding site. Examination of benzylic methylation reveals that an (R)-methyl group is four- to six-fold activating, with an optimal Ki of 630 pM for compound 11. In sharp contrast, (S)-methylation causes a > 30 to 500-fold loss of inhibitory activity, showing that the ATP-binding site of the receptor has very low tolerance for even moderate out-of-plane bulk in certain directions. It is suggested that the best of these inhibitors can induce a conformation of the kinase not available to poorer inhibitors.

Adenosine Triphosphate↗
PubMed1995

Human MHC class II gene transcription directed by the carboxyl terminus of CIITA, one of the defective genes in type II MHC combined immune deficiency.

Type II major histocompatibility complex combined immune deficiency (type II MHC CID or bare lymphocyte syndrome) is a congenital immunodeficiency disease characterized by absent MHC class II expression. Four distinct complementation groups have been identified. Recently, the defective gene in group II type II MHC CID has been isolated and termed CIITA. Here, we demonstrate that CIITA is an MHC class II gene-specific transcription activator. The transcription activation function is provided by the N-terminal acidic domain (amino acids 26-137), which is experimentally exchangeable with a heterologous viral transcription-activating domain. The specificity of CIITA for three major MHC class II genes, DR, DQ and DP, is mediated by its remaining C-terminal residues (amino acids 317-1130). The transactivation of multiple cis elements, especially S and X2, of the DR alpha proximal promoter in group II CID cells is CIITA dependent. Since CIITA overexpression in normal cells did not increase class II expression, we propose that initiation of CIITA expression serves as the on-off switch, while availability of downstream interactor(s) limits transcription.

B-Lymphocytes↗
PubMed1995

Transforming growth factor beta 1 stimulates bone formation and resorption in an in-vivo model in rabbits.

The influence of TGF beta 1 on bone was studied in a titanium device implanted into the tibia of rabbits. TGF beta 1 was infused via an Alzet osmotic pump calibrated to deliver at a rated of 200ng daily for 2 weeks before replacement. A hollow channel is incorporated into the device into which tissue can grow, and the histological sequence of events was observed over 6 weeks. In control samples, the rod-shaped piece of tissue at 2W consisted of spindle-shaped cells in the center, flanked at both ends by islands of trabecular bone lined by cuboidal osteoblasts and osteoclasts. By 4W, ingrowth of bone reached the center if the specimen, by which time, the bone surfaces were apposed by a single layer of flattened osteoblasts. However, osteoclastic resorption continued unabated so that by 6W, only a thin layer of cortical bone remained, enclosing a marrow cavity with hemopoietic elements. Significant differences were observed in samples continuously infused with TGF beta 1. At 2W, trabecular bone had reached further towards the center of the specimen and the granulation tissue was made up of cells that were more plump and cuboidal compared to the spindle cells of control sample. At 3W, there was increased bone volume and osteoid seams were thicker, covering a greater extent of the trabeculae surfaces. At 4W, the bony trabeculae were up to 3 times thicker than control trabeculae. There was very active bone resorption with many multinucleate osteoclasts and multilayered aggregates of cuboidal osteoblasts lining bony surfaces. Yet at 6W, the morphological appearance was similar to control samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Marrow development and its relationship to bone formation in vivo: a histological study using an implantable titanium device in rabbits.

During embryogenesis, the creation of marrow sinusoids is intimately related to the coupled processes of osteogenesis and osteoclastic resorption. We set out to further define the relationship between bone formation and marrow development by implanting an intraosseous titanium device into the tibiae of rabbits which permits the examination of bone formation under standardized and reproducible conditions as well as allowing repeated sampling of new bone. A hollow channel is incorporated into the device into which tissue can grow. The device was left in place for 6 weeks to allow osseous integration to occur, after which the initial rod of new tissue growth was removed and subsequent histological and immunohistological sequence of events observed over the next 7 weeks. Interpretation of its morphological changes was further aided by concurrent histomorphometric studies. Because the channel was in direct continuity with the marrow cavity and isolated from the endosteum, immediate marrow regeneration was expected, following dissolution of the blood clot. Instead, our studies indicated that hemopoietic marrow cells, including the erythroid and myeloid series as well as megakaryocytes, did not appear until 3 weeks after implantation of the chamber when the newly formed bone had been remodeled to form an expanded marrow cavity. This intraosseous device is a useful in vivo model for studying the development of bone marrow hemopoietic and nonhemopoietic stromal cells and our results confirm the previous observation that influx of marrow cellular elements follow the formation of bone during endochondral as well as intramembranous ossification.

Animals↗
PubMed1995

A Drosophila CREB/CREM homolog encodes multiple isoforms, including a cyclic AMP-dependent protein kinase-responsive transcriptional activator and antagonist.

We have characterized a Drosophila gene that is a highly conserved homolog of the mammalian cyclic AMP (cAMP)-responsive transcription factors CREB and CREM. Uniquely among Drosophila genes characterized to date, it codes for a cAMP-responsive transcriptional activator. An alternatively spliced product of the same gene is a specific antagonist of cAMP-inducible transcription. Analysis of the splicing pattern of the gene suggests that the gene may be the predecessor of the mammalian CREB and CREM genes.

Alternative Splicing↗
PubMed1995

Permeation and gating properties of a cloned renal K+ channel.

The renal K+ channel (ROMK2) was expressed in Xenopus oocytes, and the patch-clamp technique was used to assess its conducting and gating properties. In cell-attached patches with 110 mM K+ in the bath and pipette, the reversal potential was near zero and the inward conductance (36 pS) was larger than the outward conductance (17 pS). In excised inside-out patches the channels showed rectification in the presence of 5 mM Mg2+ on the cytoplasmic side but not in Mg(2+)-free solution. Inward currents were also observed when K+ was replaced in the pipette by Rb+, NH4+, or thallium (Tl+). The reversal potentials under these conditions yielded a selectivity sequence of Tl+ > K+ > Rb+ > NH4+. On the other hand, the slope conductances for inward current gave a selectivity sequence of K+ = NH4+ > Tl+ > Rb+. The differences in the two sequences can be explained by the presence of cation binding sites within the channel, which interact with Rb+ and Tl+ more strongly and with NH4+ less strongly than with K+. Two other ions, Ba2+ and Cs+, blocked the channel from the outside. The effect of Ba2+ (1 mM) was to reduce the open probability of the channels, whereas Cs+ (10 mM) reduced the apparent single-channel current. The effects of both blockers are enhanced by membrane hyperpolarization. The kinetics of the channel were also studied in cell-attached patches. With K+ in the pipette the distribution of open times could be described by a single exponential (tau 0 = 25 ms), whereas two exponentials (tau 1 = 1 ms, tau 2 = 30 ms) were required to describe the closed-time distribution. Hyperpolarization of the oocyte membrane decreased the open probability and tau 0, and increased tau 1, tau 2, and the number of long closures. The presence of Tl+ in the pipette significantly altered the kinetics, reducing tau 0 and eliminating the long-lived closures. These results suggest that the gating of the channel may depend on the nature of the ion in the pore.

Animals↗
PubMed1995

Heterogeneity in role of endothelium-derived NO in pulmonary arteries and veins of full-term fetal lambs.

Endothelium-derived nitric oxide (EDNO) modulates fetal pulmonary vasoactivity. The role of EDNO in regulation of vasomotor tone in fetal pulmonary arteries vs. that in veins is not known. We have investigated the role of EDNO in the responses of pulmonary arteries and veins of full-term fetal lambs. Fourth-generation pulmonary arterial and venous rings were suspended in organ chambers filled with modified Krebs-Ringer bicarbonate solution (95% O2-5% CO2 at 37 degrees C), and their isometric force was measured. N omega-nitro-L-arginine had no effect on the resting tension of pulmonary arteries with endothelium but caused contraction of pulmonary veins with endothelium. The basal level of intracellular guanosine 3',5'-cyclic monophosphate (cGMP) of pulmonary veins with endothelium was higher than that of arteries with endothelium. In pulmonary arteries, bradykinin, but not acetylcholine, induced endothelium-dependent relaxation and an increase in cGMP content. In pulmonary veins, acetylcholine, but not bradykinin, induced endothelium-dependent relaxation and an increase in cGMP content. Agonist-induced maximal relaxation and increases in cGMP content were smaller in pulmonary arteries than in veins. All these endothelium-dependent responses were abolished by N omega-nitro-L-arginine. In tissues without endothelium, nitric oxide induced significantly less relaxation and less increase in cGMP content in pulmonary arteries than in pulmonary veins. All vessels relaxed similarly to 8-bromoguanosine 3',5'-cyclic monophosphate. Our data suggest that the role of EDNO in modulating tone differs between pulmonary arteries and veins in full-term fetal lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗
PubMed1995

PAF induces relaxation of pulmonary arteries but contraction of pulmonary veins in the ferret.

The present study was designed to determine whether platelet-activating factor (PAF) has different effects on pulmonary arteries and veins. Third-order pulmonary arterial and venous rings of the ferret were suspended in organ chambers filled with modified Krebs-Ringer bicarbonate solution (95% O2-5% CO2, 37 degrees C) and their isometric tension was recorded. Under basal conditions, PAF had no effect on the resting tension of arteries but induced an endothelium-dependent contraction of veins. The contraction was not affected by BW-755C (an inhibitor of cyclooxygenase and lipoxygenase), BQ-123 [an antagonist of endothelin (ET) A (ETA) receptors)], or IRL-1038 (an antagonist of ETB receptors). PAF had no effect on veins during contraction to prostaglandin F2 alpha (PGF 2 alpha) but induced an endothelium-dependent relaxation of arteries. The relaxation was abolished by N omega-nitro-L-arginine. Incubation with PAF for 30 min augmented contractions of veins with endothelium to PGF 2 alpha. The augmentation was not affected by BW-755C, BQ-123, or IRL-1038. Pretreatment with PAF had no effect on the response of veins to phenylephrine or on the response of arteries to either PGF 2 alpha or phenylephrine. These observations demonstrated that, in the ferret, PAF affected differently the response of pulmonary arteries and veins and that the endothelium plays a critical role in the PAF-induced effects. Furthermore, the PAF-induced effects appear not to be mediated by metabolites of arachidonic acid and ET.

Animals↗
PubMed1995

Endothelium-derived nitric oxide plays a larger role in pulmonary veins than in arteries of newborn lambs.

In perinatal lungs, veins contribute substantially to total pulmonary vascular resistance. The present study was designed to determine the role of endothelium-derived nitric oxide (EDNO) in modulating the responsiveness of pulmonary veins and arteries in newborn lambs. Fourth-order pulmonary arterial and venous rings of newborn lambs were suspended in organ chambers filled with modified Krebs-Ringer bicarbonate solution (95% O2/5% CO2, 37 degrees C), and their isometric force was measured. Nitro-L-arginine had no effect on the resting tension of pulmonary arteries but caused an endothelium-dependent contraction of pulmonary veins. During contraction to endothelin-1 or U46619, acetylcholine, bradykinin, and calcium ionophore A23187 induced larger endothelium-dependent relaxation in pulmonary veins than in arteries. The endothelium-dependent relaxation of pulmonary vessels was abolished by nitro-L-arginine. In vessels without endothelium, nitric oxide induced significantly greater relaxation in pulmonary veins than in arteries. All vessels relaxed similarly to 8-bromo-cGMP. Radioimmunoassay showed that the basal level of intracellular cGMP of pulmonary veins with endothelium was higher than that of arteries with endothelium. Acetylcholine, bradykinin, and calcium ionophore A23187 induced a significantly larger endothelium-dependent increase in the intracellular content of cGMP in pulmonary veins than in arteries. In vessels without endothelium, nitric oxide induced a larger increase in cGMP content in pulmonary veins than in arteries. The present study suggests that EDNO may play a larger role in modulation of pulmonary venous than arterial reactivity, which may be mainly due to a difference in the activity of soluble guanylate cyclase in vascular smooth muscle.

Acetylcholine↗