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Biomedical subjects

D Zhou

Publications and source records attributed to D Zhou.

At least 361 records · Page 20Linked to original sources
PubMed1987

Association of multiple copies of the c-erbB-2 oncogene with spread of breast cancer.

Amplification of c-erbB-2 was at least three times more frequent in breast cancer than in most other types of carcinoma, and was not found in sarcomas or hematological malignancies. Amplification of c-erbB-2 was found in 15 of 86 primary breast cancers and in 3 of 12 secondary breast cancers. Amplification was more common in breast tumors of advanced stage, and in tumors which had metastasized to regional lymph nodes sites. Gene amplification was observed in 21% (4 of 19) of primary tumors which recurred within 3 years of mastectomy and in 6% (2 of 32) of nonrecurrent tumors.

Breast Neoplasms↗
PubMed1987

The effects of a stable analogue of PGE1 on the IgG subclass response to particulate bovine tubular basement membrane in the brown-Norway rat.

The IgG subclass and the IgM isotype response to immunization with particulate bovine tubular basement membrane (TBM) and adjuvants was studied in Brown-Norway rats receiving daily injections of a stable analogue of PGE1 (M-PGE1). M-PGE1 slightly reduced the average quantity of circulating TBM antibody as well as the average quantity of eluted IgG per gram of renal tissue as compared to controls. However, M-PGE1 did not qualitatively affect the distribution of the IgG subclass or IgM isotype response to TBM. The IgG response, which occurred predominantly in the IgG1 and IgG2a subclasses, increased from Days 8 to 14 after immunization, while the IgM response decreased over the same time period. The percentage of TBM antibody in the IgG2b subclass was markedly decreased as compared to the percentage of IgG2b antibody in total IgG. A substantial heterogeneity in the IgG subclass response was noted among individual rats with IgG1 constituting from 46 to 82% of circulating TBM antibody. Although no correlation between the IgG subclass response and the severity of tubulointerstitial nephritis was noted, heterogeneity in the IgG subclass response to autoantigens may, nevertheless, theoretically play an important role in the pathogenesis of autoimmune inflammatory phenomena.

Alprostadil↗
PubMed1986

Expression of immunoglobulin lambda chains in the laboratory rat.

We immunized a BALB/c mouse with the lambda-bearing rat IgG1 myeloma IR31, fused its spleen cells with the hybridoma parent line P3.X63.Ag8.653, and isolated a monoclonal antibody (G33/11) directed against rat immunoglobulin lambda chains. We used this antibody to classify two existing rat hybridomas as lambda-bearing proteins (D4.37HL.252 and PC61.5), and isolated one new lambda-bearing rat IgM hybridoma, G36/1. All the normal inbred rat sera that were tested contained lambda-bearing Ig as detected by G33/11, at levels ranging from 1.5% to 13% of the total serum Ig, the mean value being 7.9%. This antibody will be valuable for broadening our understanding of the immunogenetics of the rat, and for the characterization of monoclonal antibodies made in this species.

Animals↗
PubMed1984

Haloperidol concentrations elevated in Chinese patients.

After 6 weeks of fixed dose oral haloperidol treatment. Chinese schizophrenic patients (in the People's Republic of China) had 52% higher plasma haloperidol concentrations than U.S. non-Asian schizophrenic patients. Chinese and U.S. patients were matched for sex and body weight. The difference in plasma drug concentrations may explain why Asians are reported to require smaller dosages of neuroleptic drugs than non-Asians, and why they may be more sensitive to neuroleptic-induced side effects. When prescribing haloperidol to persons of Asian ancestry, physicians should consider that higher than expected plasma haloperidol concentrations and an increased sensitivity to haloperidol may occur.

Adult↗
PubMedDate not supplied

Phrenic response to hypercapnia in the unanesthetized, decerbrate, newborn rat.

We developed a decerebrate, vagotomized, newborn rat preparation to investigate brainstem respiratory control mechanisms without the influence of anesthesia, supra-pontine structures, or vagally mediated feedback mechanisms. We measured the changes in phrenic nerve electrical activity in response to breathing 3% and 5% CO2 in unanesthetized, vagotomized, decerebrate newborn rats from 0 to 10 days of age and compared them with the changes in anesthetized, vagotomized, newborn rats and adult, vagotomized, decerebrate or anesthetized, animals. Phrenic nerve activity was irregular in the young newborn rats and became more regular between 7 and 10 days of age. T1 and T1/Ttot increased with age but increasing age had no influence on the response to CO2. The response to CO2 was dominated by increases in phrenic amplitude, minute activity, and inspiratory slope with no change in timing variables. These responses are similar to those that have been reported previously in vagally intact animals, suggesting that vagal feedback contributes little to the response to hypercapnia in the newborn rat. In summary, decerebrate newborn rats consistently respond to hypercapnia by increasing inspiratory drive similar to conscious animals.

Animals↗
PubMedDate not supplied

Histomorphometric and biochemical study of osteoclasts at orthodontic compression sites in the rat during indomethacin inhibition.

Prostaglandins affect the number of osteoclasts at compression sites in orthodontic tooth movement. They may also have a role in tooth movement and influence the extent of root resorption. The purpose was to examine the effect of indomethacin on the activity of resident osteoclasts, recruitment of new osteoclasts and root resorption at orthodontic compression sites. Two separate populations of osteoclasts were studied: those resident at the sites after initial appliance activation and those recruited by a subsequent activation. Orthodontic appliances were activated to provide mesially directed forces of 40 g on the maxillary molars of rats. The appliances were activated with the same force after 4 days. The rats were killed at 1, 3, 6 and 10 days after initial activation. Half of the rats were injected with indomethacin. Tooth movement was measured cephalometrically; osteoclast numbers, sizes, numbers of nuclei per osteoclast and root resorption were assessed histomorphometrically; tartrate-resistant acid phosphatase (TRAP) in alveolar bone was measured biochemically. Indomethacin inhibited both initial tooth displacement and that following the delay. It also reduced the increase in osteoclast numbers, total osteoclast surface and alveolar bone TRAP at day 10. It had no effect on the surface area of each individual osteoclast or number of nuclei in each osteoclast. Root resorption increased in both groups but it was enhanced at day 10 in the indomethacin group. These data suggest that orthodontic tooth movement after appliance activation requires the recruitment of osteoclasts to sites of compression and that this is indomethacin-sensitive. Furthermore, indomethacin enhances root resorption at compression sites 10 days after appliance reactivation.

Acid Phosphatase↗
PubMedDate not supplied

Autocrine and paracrine actions of breast tumor aromatase. A three-dimensional cell culture study involving aromatase transfected MCF-7 and T-47D cells.

Stable aromatase-expressing MCF-7 and T-47D cell lines (i.e. MCF-7aro and T-47Daro) have been prepared by aromatase cDNA transfection and G418 (neomycin) selection. MCF-7aro was further subjected to a clonal purification. Aromatase activity in the transfected MCF-7 and T-47D cell lines was determined to be 73 +/- 6 pmol/mg/h and 48 +/- 4 pmol/mg/h, respectively. It is thought that these cell lines express aromatase in a stable manner, as demonstrated by a steady expression of the enzyme during culture in the absence of G418. The growth of these cells could be stimulated by androgens (1-10 nM) as demonstrated through a spheroid culture method. The androgen-stimulated growth could be suppressed by 4-hydroxyandrostenedione (4-OHA) (0.01-0.1 mM) or tamoxifen (50 nM-1 microM). In order to test the hypothesis that tumor aromatase can affect breast tumor growth in a paracrine manner, we have carried out cell culture experiments by co-culturing MCF-7 cells with either MCF-7aro or T-47Daro cells. Testosterone (1 nM) increased cell growth to a similar degree for MCF-7/MCF-7aro co-culture (0.75 x 10(6) cells each type) as with MCF-7aro only (2- to 3-fold). In addition, the enzyme activities remained unchanged for MCF-7/MCF-7aro co-culture samples with and without androgen treatment, indicating that estrogen produced by transfected cells can also stimulate the growth of untransfected cells. The androgen response could be inhibited by an addition of 4-OHA (0.01-0.1 mM). For MCF-7/T-47Daro co-culture experiments, a clear induction of cell growth by androgen was observed, and the level of the increase was similar to that on T-47Daro only. However, for either culture with T-47D only or with MCF-7/T-47Daro co-culture, the aromatase activity was found to increase significantly after testosterone treatment. T-47Daro cells were not subjected to a clonal purification, and it is therefore thought that the androgen treatment may selectively stimulate the growth of high aromatase-expressing T-47Daro cells. These results indicate that estrogen synthesized by tumor aromatase can stimulate breast tumor growth in both an autocrine and a paracrine manner.

Androgens↗