Search PubMed⌕ Search

Biomedical subjects

D T Liu

Publications and source records attributed to D T Liu.

At least 37 records · Page 2Linked to original sources
PubMed1995

Endometrial leukocyte subpopulations in women with endometriosis.

The aim of this study was to investigate whether the endometrium of women with endometriosis differs immunologically from the endometrium of normal fertile women. Endometrial biopsies were obtained from 18 normal fertile women who were requesting sterilisation or reversal of sterilisation and 21 infertile women who had laparoscopically diagnosed pelvic endometriosis. The endometrial biopsies were obtained from both groups during the either early, mid or late luteal phase of the menstrual cycle. A panel of 11 monoclonal antibodies and immuno-histochemical techniques were employed to characterise the endometrial stromal leukocytes in frozen sections. Image analysis was used for semi quantitation of leukocytes. In both groups, the number of endometrial granulated lymphocytes (CD56+ CD38+ cells) and macrophages (CD68+ cells) increased significantly between the early and late luteal phase of the menstrual cycle. Compared with fertile controls, women with endometriosis had fewer T-suppressor/cytotoxic (CD8+) cells and endometrial granulated lymphocytes but more T-helper/inducer (CD4+) cells, CD68+ cells and CD16+ cells. None of these differences reached a statistically significant level. This study has shown that the endometrial lymphoid tissue of women with endometriosis does not differ qualitatively or quantitively from that of normal fertile controls. However, functional differences of endometrial leukocytes between the two groups cannot be excluded.

Adult↗
PubMed1995

Renin mRNA, quantified by polymerase chain reaction, in renal hypertensive rat tissues.

To determine responses in renin gene expression in different tissues of two-kidney, one clip hypertensive Sprague-Dawley rats and the effect of NaCl loading, we developed a novel, highly sensitive quantitative polymerase chain reaction technique and measured renin mRNA at 19 and 40 days after clipping. Basal renin mRNA concentrations were 1575 +/- 127 fg/micrograms total RNA in kidney, 52 +/- 7 in hypothalamus, 7.9 +/- 0.7 in adrenal, and 4.7 +/- 0.5 in atria. In two-kidney, one clip rats, renin mRNA in the clipped kidney was increased 5.4-fold (P = .00001) and 2.3-fold (P = .001) on each respective day after clipping and in the unclipped kidney was decreased by 27% (P = .01) and 38% (P = .04). In adrenal, 3.9-fold (P = .004) and 1.7-fold (P = .02) increases were seen on days 19 and 40, respectively, and a decrease of 57% (P = .02) was found in a hypothalamic block at day 19 but not at day 40. The decrease in hypothalamus was abolished by 1% oral NaCl, which reduced renin mRNA by 37% in the clipped kidney and by 30% in the adrenal but did not lead to any change in the unclipped kidney or hypothalamus at day 40. Hypothalamic renin mRNA was also decreased by enalapril compared with increases of sixfold to ninefold in other tissues. In conclusion, we have quantified a decrease in hypothalamic renin mRNA in two-kidney, one clip rats 19 days after clipping that can be abolished by NaCl loading, whereas in the adrenal, renin mRNA was increased. Similar relative tissue-specific changes were also seen in enalapril-treated rats.

Actins↗
PubMed1995

Long-term storage of human fetal haematopoietic progenitor cells and their subsequent reconstitution. Implications for in utero transplantation.

Haematopoietic progenitor cells were isolated from human fetal liver, obtained between 6 and 15 weeks gestation. After preparation of a single cell suspension, the cells were stored using a stepwise freezing protocol; taking the cells from room temperature through -70 degrees C to liquid nitrogen. Viability (trypan blue exclusion), morphology (Leishman stain), identification of cell type (flow cytometry) and growth characteristics in semi-solid culture medium were assessed using the fresh cell suspension. We were able to confirm that the predominant cells in human fetal liver up to about 15 weeks gestation are those of the erythroid lineage. It was established that viability in excess of 75% was required to ensure adequate growth in culture after frozen storage and it was deemed important to ensure morphological integrity of the cell preparations. The colonies formed in culture were observed to be producing haemoglobin between 7 and 9 days after initial seeding. We have determined that cells can be stored in liquid nitrogen for up to 2 years without loss of (1) viability, (2) morphological features and (3) ability to form colonies and produce haemoglobin in culture. These findings offer encouragement for the implementation of a cell bank to support an in utero transplantation programme.

Cell Separation↗
PubMed1994

Screening of monoclonal antibodies recognizing oncofetal antigens for isolation of trophoblasts from maternal blood for prenatal diagnosis.

Many monoclonal antibodies have been produced against tumour-associated cell surface antigens for cancer therapy. They have therefore been selected for minimal reactivity with normal tissues and in particular for lack of binding to blood cells or serum components. Many of the antigens recognized are of fetal origin. These monoclonal antibodies may therefore be ideal candidates to recognize and sort fetal trophoblasts from maternal blood for prenatal diagnosis of genetic abnormalities. A panel of 19 anti-tumour antibodies were therefore screened for reactivity with early trimester placenta and two, 340 and 154, were shown to stain trophoblasts. If MAb 340 is linked to magnetic beads, it can efficiently sort trophoblast cell lines from whole blood.

Antibodies, Monoclonal↗
PubMed1994

Effects of dietary magnesium on blood pressure and vascular lesions in hypertensive rats.

The present study examines the effects of dietary magnesium on the development of hypertension and hypertensive vascular lesions in deoxycorticosterone acetate and salt induced (DOCA-salt) and 2 kidney one clip (2K1C) hypertensive as well as normotensive control rats. Animals received a regular (0.12% Mg), high (0.4% Mg) or low (0.03% Mg) magnesium diet for 6 wks. Dietary magnesium did not alter the growth or blood pressure in control, DOCA-salt and 2K1C rats even though the plasma magnesium concentration was significantly altered by the diets (ANOVA, p < 0.05 in control, DOCA-salt and 2K1C, respectively). Dietary magnesium did not alter the urinary potassium excretion, plasma sodium, potassium, total calcium concentration and plasma renin activity in any group, while the high magnesium diet significantly increased the urinary sodium excretion in DOCA-salt (p < 0.05) but not in control and 2K1C rats when compared with the regular magnesium diet. In histological studies, dietary magnesium did not alter the percentage media area of intramyocardial arteries, or glomerular and renal arterial and arteriolar lesions in DOCA-salt and 2K1C rats. This study suggests that moderate alterations of dietary magnesium do not modify blood pressure in normotensive control, DOCA-salt and 2K1C hypertensive rats, nor do they modify vascular disease in these 2 hypertensive models.

Animals↗
PubMed1994

The effects of dietary potassium on vascular and glomerular lesions in hypertensive rats.

The present study examines the effects of dietary potassium (K) on hypertensive glomerular and vascular lesions in deoxycorticosterone acetate and salt induced (DOCA-salt) and two kidney one clip (2K1C) hypertensive as well as normotensive control rats. Animals received a regular (0.28% K), high (1.1% K) or low (0.07% K) potassium diet for 6 weeks. In control rats, low K diet significantly increased systolic blood pressure (SBP) (p < 0.05). In DOCA-salt rats, high K diet did not modify SBP or glomerular and vascular lesions while low K diet significantly increased premature death in these rats. In 2K1C rats, dietary K did not alter the blood pressure, but percentage media area (% media) of intramyocardial arteries, percentage of glomerular lesions, and renal arterial and arteriolar lesion scores were lower in high K diet rats than regular and low K diet rats (p < 0.05). This study is the first demonstration that high K diet can protect against vascular and glomerular lesions in a non salt-loaded hypertensive model. The beneficial effects of dietary K on vascular lesions are at least in part independent of changes in blood pressure, and may be renin related.

Animals↗
PubMed1994

Digoxin amplifies the effects of deoxycorticosterone acetate (DOCA) in intact water-drinking rats: implications for the mechanism of DOCA hypertension?

INTRODUCTION: An increase in digitalis-like substances has been reported in deoxycorticosterone acetate (DOCA)-salt hypertensive rats. We hypothesized that the role of saline and unilateral nephrectomy in DOCA hypertension may be due to stimulation of endogenous digitalis-like substances. METHODS: We investigated the effects of digoxin and DOCA alone and in combination in intact rats drinking water. Forty male Sprague-Dawley rats were used (body weight 223-298 g). RESULTS: Neither digoxin (40 micrograms/kg per day, by gavage, for 35 days, n = 10) nor DOCA (30 mg/kg twice a week, subcutaneously, for 5 weeks, n = 10) caused a consistent increase in blood pressure in intact rats drinking water. In contrast, combined digoxin and DOCA administration (n = 10) increased systolic blood pressure from day 18 of treatment onwards, to a maximum at day 34 compared with sham-treated rats (n = 10). There were no consistent changes in water intake, urine volume, urinary sodium or potassium excretion, or plasma sodium or potassium concentration with digoxin treatment. DOCA increased water intake and urine volume, and caused an initial decrease in urinary sodium excretion, but no change in urinary potassium excretion or plasma sodium concentration. Plasma potassium excretion was lower in DOCA- than sham-treated rats. CONCLUSION: Combined digoxin and DOCA administration in intact rats drinking water increased blood pressure significantly compared with either drug alone, raising the possibility that the mechanism by which nephrectomy and salt loading contribute to DOCA hypertension in the rat might be through stimulation of endogenous digitalis-like substances.

Animals↗
PubMed1994

Effect of dietary calcium on the development of hypertension and hypertensive vascular lesions in DOCA-salt and two-kidney, one clip hypertensive rats.

OBJECTIVE: To examine the effect of modest changes in dietary calcium on systolic blood pressure (SBP) and myocardial and renal vascular lesions in Sprague-Dawley rats. DESIGN: Regular- (0.4%, by weight), high- (0.8%) or low-calcium (0.24%) diets were fed to normotensive control, deoxycorticosterone acetate (DOCA)-salt and two-kidney, one clip (2-K, 1C) hypertensive rats for 8 weeks. METHODS: Tail-cuff SBP and metabolic balance were measured once a week. At the end of the study the kidneys and hearts were collected for histological study. RESULTS: Dietary calcium had no effect on SBP in the DOCA-salt rats, but loading with calcium accelerated the rise in SBP in 2-K,1C rats (P < 0.01, high- versus regular-calcium diet). The high-calcium diet reduced the percentage medial area of intramyocardial arteries in the DOCA-salt and 2-K,1C hypertensive rats. The DOCA-salt rats on the low-calcium diet had a higher renal vascular lesions score than those on the regular- or high-calcium diet (P < 0.05). CONCLUSIONS: A high-calcium diet appears to prevent intramyocardial vascular wall thickening in DOCA-salt and 2-K,1C hypertensive rats, and a low-calcium diet aggravates renal vascular lesions in DOCA-salt hypertensive rats. These effects are not related simply to changes in blood pressure.

Animals↗
PubMed1993

Effect of dietary sodium chloride on the development of renal glomerular and vascular lesions in hypertensive rats.

1. The hypothesis that high levels of NaCl in the diet aggravates hypertension-associated renal vascular lesions was examined in unilaterally nephrectomized deoxycorticosterone acetate treated (DOCA) and two kidney one clip (2K1C) hypertensive rats, as well as normotensive controls. 2. High NaCl diet significantly increased systolic blood pressure (SBP) in DOCA rats, but had little effect on SBP in normal control rats, and did not affect the rise of SBP in 2K1C rats. 3. High NaCl diet was associated with a higher percentage of glomerular lesions and renal arterial and arteriolar lesions in DOCA and 2K1C rats (P < 0.05). 4. Thus high NaCl intake exacerbated renal arterial and arteriolar and glomerular lesions in both DOCA and 2K1C hypertensive rats. In 2K1C rats this effect may be in part independent of blood pressure.

Animals↗
PubMed1992

Primary structure of thymosin beta 12, a new member of the beta-thymosin family isolated from perch liver.

A new polypeptide termed thymosin beta 12 has been isolated from perch liver and its primary structure elucidated. This polypeptide contains 43 amino acid residues with a molecular weight of 4822 Da. The content of thymosin beta 12 from perch liver has been determined as 43 micrograms/g of tissue. The amino-terminal end of this polypeptide is blocked by an acetyl group as deciphered by fast-atom bombardment mass spectrometric analysis. Sequence analysis reveals that thymosin beta 12 is 79% homologous to thymosin beta 4, an immunomodulator which was originally isolated from calf thymus. Thymosin beta 12 also shows 84% sequence homology to thymosin beta 11, a beta 4 analog which replaces beta 4 in two species of bony fish, oscar and rainbow trout. The evolutionary implication of such results will be discussed. The isolation of a new beta 4-related peptide from perch liver which differs from beta 11 indicates that beta-thymosin peptides are widely distributed in lower vertebrate classes.

Amino Acid Sequence↗