Biomedical subjects

C Y Guo

Publications and source records attributed to C Y Guo.

At least 37 records · Page 2Linked to original sources

PubMed1997

Treatment of isolated hypogonadotropic hypogonadism effect on bone mineral density and bone turnover.

Isolated hypogonadotropic hypogonadism (IHH) presents with delayed puberty in the late teens or early twenties, with a period of testosterone deficiency during active growth. The aims of the study were to determine 1) whether long term treatment of IHH results in normalization of bone density (BMD) and bone turnover, and 2) whether BMD and bone turnover respond to increasing doses of hCG. We studied 10 men, aged 26-46 yr, with IHH who were treated with hCG or testosterone esters (Sustanon) for 2-22 yr, with age at the start of treatment between 17-29 yr, and 10 age- and body weight-matched normal men as a control group. At baseline, lumbar spine, femoral neck, trochanter, and Ward's triangle BMD values were decreased, and serum bone Gla-protein, bone alkaline phosphatase, and urinary pyridinoline, deoxypyridinoline, and N-terminal telopeptide of type I collagen were increased compared with control values (by paired t test, P = 0.02, 0.03, 0.01, 0.05, 0.002, 0.02, 0.02, 0.007, and 0.006, respectively). The age at initial therapy was significantly correlated with total body BMD (r = -0.73; P = 0.017) and lumbar spine BMD (r = -0.756; P = 0.0097). Serum free testosterone was correlated with total body and trochanter BMD (r = 0.635; P = 0.048 and r = 0.629; P = 0.05), and serum free estradiol was correlated with total body and trochanter BMD (r = 0.641; P = 0.045 and r = 0.634; P = 0.048). Six of the 10 patients were recruited for a longitudinal study in which the dose of hCG was increased monthly from 2000 i.u. twice per week to 6000 i.u. twice per week. After increasing doses of hCG, levels of serum testosterone and estradiol and total body BMD increased significantly (by paired t test P = 0.001, 0.003, and 0.01, respectively). Serum bone Gla-protein levels increased by the first month and then decreased (paired t test, corrected by Bonferroni's method). Serum bone alkaline phosphatase and urinary N-terminal telopeptide of type I collagen/creatinine levels decreased significantly after increasing the dose of hCG. We conclude that patients with IHH who have serum testosterone within the laboratory reference range may require a higher dose of hCG to normalize BMD and bone turnover.

Adult↗

PubMed1996

Metabolic effects of pamidronate in patients with metastatic bone disease.

We have evaluated the value of specific bone resorption markers in monitoring metastatic bone disease to define the duration of action of a single high-dose pamidronate infusion. Twenty patients received a single infusion of pamidronate 120 mg for painful bone metastases. Ten out of these 20 patients also received a second infusion. They were evaluated at baseline, 2, 4 and 8 weeks after each infusion. A composite pain questionnaire, serum and urine tests were carried out at these time points. Bone resorption markers measured included urinary calcium, hydroxyproline and two new markers: pyridinoline and deoxypyridinoline. Reference values were defined by 20 healthy controls matched by age and sex. Pamidronate induced a profound fall in bone resorption with a maximal effect within the first month after therapy. Changes in urinary calcium levels were confounded by a rise of 100% in the parathyroid hormone levels. Before treatment, pyridinoline and deoxypyridinoline were increased in 70% of patients, while urinary calcium was increased in only 40% of them. Thirteen patients had a > or = 50% fall in deoxypyridinoline levels and were considered as biochemical responders. These patients had a mean reduction in pain score of about 30% of baseline levels, which was significantly higher than the seven non-biochemical responders. In conclusion, urinary calcium is not a precise marker of bone resorption. Deoxypyridinoline seems to be the most specific bone resorption marker in cancer patients. Biochemical responders have the most benefit from pamidronate in terms of pain relief. This suggests that patients may benefit from more potent or repeated infusions of bisphosphonates.

Aged↗

PubMed1996

Bone turnover and bone mineral density in patients with congenital adrenal hyperplasia.

BACKGROUND AND OBJECTIVE: Glucocorticoid replacement is the most effective therapy for patients with congenital adrenal hyperplasia (CAH). It has been reported that excessive steroid therapy leads to bone loss and osteoporosis, but it is uncertain whether steroid replacement therapy affects bone turnover and bone mineral density (BMD) in adult patients with CAH. DESIGN: Case-control study: patients with CAH were compared to normal subjects, individually matched for age and body weight. PATIENTS: Eleven patients, aged 19-65 years, were evaluated in this study. The age at diagnosis of CAH was 0-26 years. Nine patients (6 females and 3 males) were diagnosed with 21-hydroxylase deficiency and 2 male patients with 11-hydroxylase deficiency. 17-Hydroxyprogesterone levels in patients had never been below the reference range in the previous 2 years. These patients were individually matched for sex, age and weight to 11 healthy controls. MEASUREMENTS: Total body, lumbar spine and femoral neck BMD was measured by dual-energy X-ray absorptiometry. Serum bone Gla-protein (BGP, osteocalcin) and bone alkaline phosphatase (BAP) were measured to assess bone formation whereas serum tartrate-resistant acid phosphatase (TRAP) and urinary cross-linked N-telopeptides of type I collagen (NTx) were measured to assess bone resorption. NTx was expressed as a fraction of urinary creatinine excretion (NTx/Cr). Serum dehydro-epiandrosterone sulphate (DHEA-S) and androstenedione levels were measured to assess adrenal androgen status. RESULTS: Serum DHEA-S, androstenedione, BGP and BAP and urinary NTx/Cr were decreased in patients when compared with controls (paired t-test, P = 0.005, 0.0003, 0.002, 0.03 and 0.03, respectively). BMD was not significantly decreased in patients. The difference of total body BMD between patients and controls (i.e. BMD in patients minus BMD in controls) was negatively correlated with age. There was no correlation between androgen levels and either BMD or bone turnover. The total dose of steroid taken in the previous 2 years was not correlated with BMD, bone turnover or androgen levels. The was no correlation between BMD adjusted by age and bone turnover or initial age at diagnosis. CONCLUSIONS: We conclude that (1) bone turnover is decreased in congenital adrenal hyperplasia, (2) bone mineral density is not decreased in congenital adrenal hyperplasia and (3) patients initially have higher bone mineral density but later have lower bone mineral density than controls, especially in women.

Adrenal Hyperplasia, Congenital↗

PubMed1996

Longitudinal changes in bone mineral density and bone turnover in postmenopausal women with primary hyperparathyroidism.

The aims of this study were to determine 1) whether primary hyperparathyroidism (PHPT) is associated with accelerated bone loss in postmenopausal women, 2) whether bone mineral density (BMD) and bone turnover change to a similar extent with surgery and hormone replacement therapy (HRT) in these patients, and 3) whether biochemical markers of bone turnover measured at baseline can be used to predict the change in BMD in these patients after different therapies. We studied 33 postmenopausal women with PHPT; their ages at the time of study ranged from 48-80 yr (mean +/- SD, 63 +/- 10). Total body (TB), lumbar spine (LS), and femoral neck (FN) BMD and biochemical markers of bone turnover were measured at baseline and 10-30 months (19 +/- 5) after parathyroid surgery, HRT, or no treatment. BMD was measured in 33 age-matched healthy controls at baseline and at a mean of 24 months. Baseline biochemical markers of bone turnover were measured in controls. In PHPT at baseline, the mean z-score of BMD was -1.25 at TB (95% confidence interval, -1.64 to -0.86), -0.95 at LS (-1.37 to -0.53), and -1.30 at FN (-1.65 to -0.95), whereas the mean z score was 0.45 for serum carboxy-terminal propeptide of human type I procollagen (0.02-0.89), 1.05 for bone alkaline phosphatase (0.38-1.71), 2.38 for 24-h urinary excretion of cross-linked N-terminal telopeptide of type I collagen (NTx; 1.63-3.13), and 2.36 for 24-h urinary excretion of galactosyl hydroxylysine (1.97-2.74). After surgery and HRT, BMD increased and bone turnover decreased during the follow-up. In the untreated group, BMD decreased at TB and FN, and levels of bone alkaline phosphatase, NTx/creatinine, and galactosyl hydroxylysine/creatinine increased. When the rate of change in BMD (percentage per yr) was compared with that in the control group, bone gain was significant at all three skeletal sites after surgery and HRT, and bone loss was significant at TB and FN, but not at LS, in the untreated group. There was a weak, but significant, correlation between baseline urinary NTx and the change in femoral neck BMD in the untreated group (r = -0.36; P = 0.05). We conclude that untreated postmenopausal women with PHPT have low BMD resulting from accelerated bone loss at the TB and FN. Surgery and HRT both restore BMD and bone turnover toward normal in postmenopausal women with PHPT. A single measurement of bone turnover is insufficient to predict BMD changes in individual patients with PHPT.

Aged↗

PubMed1994

[Determination of tetramethylpyrazine and borneol in human plasma by GC-MSD].

A GC-MSD method for the determination of tetramethylpyrazine (TMP) and borneol in plasma is described. TMP and borneol were extracted with hexane-dichloromethane (10:1, V/V). Camphor was used as the internal standard. The average recoveries of TMP and borneol were 87.38% and 97.32% with relative standard deviation 1.90% to 6.21%, respectively. The method was successfully used to determine plasma borneol concentration following sublingual administration of 20 pills of Suxiao Jiuxin Wan to healthy volunteers (n = 10). The pharmacokinetic parameters have been listed in this paper.

Adult↗

PubMed1994

[Inhibitory effect of a third generation retinoid R8923 and all-trans retinoic acid on two-stage chemical carcinogenesis of BALB/3T3-A31 cells in vitro].

The inhibitory effect of a third generation retinoid R8923 and all-trans retinoic acid (RA) on malignant transformation of Balb/3T3-A31 cells induced by 3-methylcholanthrene (3-MCA) and 12-0-tetradecanoyl phorbol-13-acetate(TPA) was studied in paper. Malignant transformation of Balb/3T3-A31 cells was evaluated by scoring transformation foci and soft agar assay. Actively growing Balb/3T3-A31 cells (1.5 x 10(4) cells per 60-mm-diameter glass dish) were cultured in 5ml of Eagle's Minimum Essential Medium supplemented with 10 percent fetal bovine serum. Twenty-four hours after plating, the cells were treated with 3-MCA (2 micrograms/ml) for 72 hours. TPA was added into the medium at a concentration of 100 ng/ml for 2 weeks. Thirty-six days after cell plating, the transformation foci were counted and the soft agar assay of the cells isolated from each glass dish was performed. Results showed that there were 16.0 +/- 1.58 transformation foci/dish and the colony forming efficiency in soft agar assay was 138.6 +/- 14.47/10(3) cells in 3-MCA and TPA treated dishes (control group). When the cells were exposed to R8923 or RA (at a concentration of 10(-6) M), the transformation foci were 11.2 +/- 0.84 /dish and 9.2 +/- 1.10/dish respectively, and the corresponding colony forming efficiency values were 66.1 +/- 7.68/10(3) cells and 64.8 +/- 4.46/10(3) cells. They were significantly lower than that of the control group. These results demonstrated that R8923 and RA could effectively inhibit 3-MCA and TPA induced malignant transformation of Balb/3T3-A31 cells and suggested that R8923 is a potential drug for cancer chemoprevention.

3T3 Cells↗

PubMed1992

Functionalized, probe-containing, latex nanospheres.

Synthesis of surface-functionalized, probe-containing latex nanospheres is described. Approximately 40,000 probe ions may be encapsulated in a nanosphere of 50 nm diameter. The probe may be a radionuclide or a lanthanide with long-lived fluorescence. Alternatively, a "cargo" of pharmaceutical interest may be used. The surface of each nanosphere contains thousands of acid groups which may be functionalized for subsequent attachment to biomolecules such as antibodies. Functionalized nanospheres have been successfully coupled to a tobacco virus.

Biotin↗

PubMed1991

Treatment of isolated systolic hypertension in the elderly.

Isolated systolic hypertension affects between 10 and 20% of the elderly population and carries a substantial risk of cardiovascular complications. As no prospective, randomized trials have produced scientific evidence of a treatment benefit in elderly patients with isolated systolic hypertension, opinion on when and how to treat this condition differs among expert committees as well as among individual doctors. This article reviews the present treatment policies in patients with isolated systolic hypertension. It describes the ongoing intervention studies that have been designed to examine the hypothesis that antihypertensive treatment confers a benefit to elderly patients with isolated systolic hypertension in terms of a reduced morbidity and mortality. The Syst-Eur trial, which was recently initiated by the European Working Party on High Blood Pressure in the Elderly, is described in greater detail.

Aged↗

PubMed1991

Duration of immunity following immunization with live measles vaccine: 15 years of observation in Zhejiang Province, China.

The duration of immunity following measles vaccination of 2882 immunized children has been investigated in a closed region of China for 15 years. A total of 1002 of the children were treated as primary immunization subjects, and 1547 as reimmunization subjects. These two cohorts were not in contact with known wild measles virus over the whole observation period, and the results obtained probably reflected the antibody responses to measles vaccine alone. The remaining 333 vaccinees came into contact with wild measles virus, and this permitted evaluation of the protective effect of the measles vaccines tested: 4 children experienced very mild clinical measles, and 329 experienced subclinical infection, including 12 who had had undetectable haemagglutination-inhibition antibodies for 9-10 years. These results indicate that the immunity induced by successful primary immunization may persist for at least 15 years. Within this period, a second dose of vaccine only induces low antibody responses which decrease rapidly to their original levels. This provides strong evidence that the immunity produced by primary immunization is long-lasting. However, there were some indications that reimmunization might produce better effects if live attenuated measles virus were used with a longer interval between doses.

Adolescent↗

PubMed1990

[Etiological and influential factors of involutional osteoporosis in old Chinese].

A comprehensive analysis is reported in 376 healthy middle and old-age persons, including measurements of bone mineral content (BMC) of the mid-radias, pituitary sex hormones (RIA), serum calcium, phosphate, albumin, alkaline phosphatase, urinary calcium, phosphate, hydroxyproline (BCA), daily intake of protein and calcium, physical exercise and activity, body weight, amenorrhea etc. Results showed that the preponderance of bone resorption over bone formation is the essential pathophysiological change of involutional osteoporosis. For females, bone loss is regulated mainly by estrogen in presenile group, co-regulated by estrogen and androgen in senile group. For males, urinary hydroxyproline excretion is also regulated by estrogen A remarkable correlation was observed between BMC and the following factors: serum calcium, urinary calcium, hydroxyproline, body weight, physical exercise, amenorrhea, intake of protein and calcium. Our data indicated that the intake of calcium daily in old chinese should not be lower than 700 mg (male) and 900 mg (female), protein should not be lower than 60-70 g. The age of onset, prevalence rate and BMC average reduction rate of osteoporosis in chinese were also observed in the studies.

Aged↗

PubMed1990

[Effect of 2-naphthyl-3- (3,4-dimethoxy) phenyl-propenoic acid on the metabolism of arachidonic acid in rabbit platelets].

Washed rabbit platelets were incubated with [14C] arachidonic acid (AA sodium salt) after being exposed to 2-naphthyl-3-(3,4-dimethoxy) phenyl-propenoic acid (NM-PA), indomethacin (Ind) and imidazole (Imi) or control solvent. The metabolites of AA in rabbit platelets were separated with the system of chloroform: methanol: acetic acid: water (90:8:1:0.8) by thin layer chromatography and quantitated by liquid scintillation counter. The metabolism of AA was influenced by NMPA dose-dependently in the range of 0.05-0.5 mmol/L. The formation of thromboxane B2 (TXB2) and 12-hydroxy-5,8,10-heptadecatrienoic acid (HHT), the final metabolites in the pathway of cyclooxygenase-thromboxane synthetase, were decreased from 24 +/- 6.7 to 3.2 +/- 1.6% and 10.3 +/- 2.49 to 4.7 +/- 2.8%, respectively. Meanwhile, 12-hydroxy-5,8,10,14-eicosatetraenoic acid (12-HETE), the metabolite in the pathway of lipoxygenase, was increased from 11.9 +/- 1.7 to 34 +/- 5.6%. It is suggested that NMPA blocks the pathway of cyclooxygenase-thromboxane synthetase and then changes the direction of arachidonate metabolism in platelets, the activation of platelets is inhibited in this way.

Animals↗

PubMed1989

[Effect of Rheum tanguticum Maxim ex Balf on cAMP in the central nervous system].

Rabbit model of fever was produced by means of subcutaneous inoculation of pneumocci. Third ventricular intubation and irrigation were carried out in rabbits. Irrigation fluid was collected during the stage of normal temperature, at the peak of fever and when the temperature was lowered by rhubarb. cAMP was detected with RlA in each of the three portions of the irrigated CSF. The result showed that cAMP level was raised during fever and decreased after rhubarb administration. Irrigation of CSF without medication had no significant influence on cAMP level.

Animals↗

PubMed1989

[Effects of rhubarb on arachidonic acid metabolism of the renal medulla in the rabbit].

The effects of rhubarb on arachidonic acid metabolism in renal medulla of rabbits were studied in vitro with radiochromatography and radioautography. The results showed that radioactive agent was markedly reduced in the rhubarb group and significant difference vs the control was observed (P less than 0.01). The results indicated that rhubarb blocked the biosynthesis of renal medulla PGE2 and PGF2 alpha in a dose-dependent manner. Also the rhubarb inhibited the biosynthesis of PGA2 and TXB2. It was suggested that the site of action of the rhubarb is at cyclooxygenase level.

Animals↗

PubMed1989

[Electrophysiologic study of concealed accessory A-V pathway].

The presence of concealed accessory A-V pathways (CAP) was demonstrated in 14 out of 18 (78%) patients with supraventricular tachycardia (SVT) and narrow QRS complexes. Such a high percentage of CAP mediated AVRT is a quite unique finding. The importance of a standard programmed electrical stimulation protocol in documenting CAP is emphasized. Careful atrial mapping and premature ventricular stimulation during SVT are very helpful for diagnosis and localization of CAP. We considered that a V-A interval of 75 ms or more on intracardiac electrogram or a R-P interval of 85 ms or more on esophageal electrogram is a good criterion for AVRT utilizing an accessory pathway.

Adolescent↗

PubMed1988