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Biomedical subjects

H C Lin

Publications and source records attributed to H C Lin.

At least 37 records · Page 2Linked to original sources
PubMed2001

Synthesis and DNA nicking studies of a novel cyclic peptide: cyclo[Lys-Trp-Lys-Ahx-].

Two novel cyclic tetrapeptides: cyclo[Lys-Tyr-Lys-Ahx-] 7a and cyclo[Lys-Trp-Lys-Ahx-] 7b were synthesized by coupling protected amino acid in solution and the subsequent cyclization effected by the pentafluorophenyl ester method as described in previous papers. These cyclic peptides were designed and synthesized to study their interaction with DNA, based on previous reports that linear peptides Lys-Tyr-Lys and Lys-Trp-Lys could bind to various forms of DNA and cleaved supercoiled DNA at apurinic sites. Ethidium bromide displacement assay showed that the apparent DNA binding constant of linear Lys-Tyr-Lys and cyclic peptide 7a are far below 1 x 10(3) M(-1), whereas those of cyclic peptide 7b and linear Lys-Trp-Lys are 1.9 x 10(4) M(-1) and 9.5 x 10(3) M(-1), respectively. Kinetic studies using agarose gel electrophoresis showed that cyclic peptide 7b and Lys-Trp-Lys possessed DNA nicking activity on natural supercoiled phi X174 DNA with nicking rate of 50.7 and 75.6 pM min(-1) at 65 degrees C, respectively, whereas cyclic peptide 7a and linear Lys-Tyr-Lys were devoid of the corresponding activity. The DNA nicking rate increased significantly with increase in reaction temperature. At reaction temperatures lower than 65 degrees C, the DNA nicking rate of cyclic peptide 7b exceeded that of linear Lys-Trp-Lys. The addition of 1 microM ferrous ion did not give significant enhancement effect on the DNA nicking rate by the peptides. UV irradiation gave a marked rate enhancement on the DNA nicking rate of linear Lys-Trp-Lys and a moderate enhancement on the DNA nicking rate of cyclic peptide 7b.

DNA↗
PubMed2001

Two new fatty diterpenoids from Salvia miltiorrhiza.

Two new fatty abietane diterpenoids, oleoyl neocryptotanshinone (1) and oleoyl danshenxinkun A (2), were isolated as minor components from the roots of Salvia miltiorrhiza. Their structures were established on the basis of spectral evidence. In preliminary tests, they selectively inhibited rabbit platelet aggregation induced by arachidonic acid.

Animals↗
PubMed2001

The alkaloids of Artabotrys uncinatus.

A novel type of alpha,beta-butenolide alkaloid, uncinine (1), two novel oxoaporphines, artabonatine C (2) and artabonatine D (3), a new oxazoloaporphine, artabonatine E (4), and a new 7,7'-bisdehydroaporphine, artabonatine F (5), along with 25 known alkaloids, were isolated from Artabotrys uncinatus. The structures of 1-5 were determined using NMR and mass spectral data. Atherospermidine and squamolone exhibited cytotoxicity against hepatocarcinoma cancer cell lines (Hep G(2) and 2,2,15), and the activity of some of the alkaloids in an antithrombin assay is also discussed.

Alkaloids↗
PubMed2001

Intestinal transit in dogs is accelerated by volume distension during fat-induced jejunal brake.

Intestinal transit is accelerated by volume distension and slowed by nutrient load. We hypothesized that the accelerating effect of volume distension might overcome the slowing effect of nutrient. To test this hypothesis, we compared intestinal transit in five dogs equipped with duodenal and mid-intestinal fistulas. The proximal half of the small intestine was perfused with 60 mM oleate, while the distal half of the small intestine was either perfused with buffer (with distension) or left unperfused (without distension). We found that intestinal transit was slowed by oleate (with marker recovery reduced from 85.8 +/- 5.3 to 39.4 +/- 7.5%) (P < 0.01) and that volume distension accelerated intestinal transit so that marker recovery increased from 39.4 +/- 7.5 without distension to 60.8 +/- 6.3% with distension (P < 0.05). We concluded that intestinal transit is accelerated by volume distension during fat-induced jejunal brake.

Animals↗
PubMed2001

Slowing of gastrointestinal transit by oleic acid: a preliminary report of a novel, nutrient-based treatment in humans.

Chronic diarrhea may occur when gastrointestinal transit is abnormally rapid. We hypothesized that oleic acid given prior to a meal would slow gastrointestinal transit and reduce diarrhea by activating nutrient-triggered inhibitory feedback mechanisms in the small intestine. Transit time was measured in eight normal subjects following ingestion of a control emulsion (0 ml oleic acid), and in 45 patients with chronic diarrhea following ingestion of emulsions containing 0, 1.6, and 3.2 ml oleic acid. Stool volume and frequency on and off treatment were compared. Transit time in normal subjects was 102.4 +/- 11.2 min (mean +/- SE). Transit times in patients was shorter at 29.3 +/- 2.8 min with the 0-ml dose (P < 0.001), but increased to 57.2 +/- 4.5 min with the 1.6-ml dose and to 83.3 +/- 5.2 min with the 3.2-ml dose (P < 0.001). In the 18 patients who provided stool records, frequency of bowel movements decreased from 6.9 +/- 0.8 to 5.4 +/- 0.9 bowel movements/24 hr (P < 0.05) and stool volume decreased from 1829.0 +/- 368.6 to 1322.5 +/- 256.9 ml/24 hr with treatment (P < 0.05). An emulsion containing oleic acid slowed gastrointestinal transit and reduced diarrhea by activating nutrient-triggered inhibitory feedback mechanisms in the small intestine.

Adolescent↗
PubMed2001

Postprandial improvement of gastric dysrhythmias in patients with type II diabetes: identification of responders and nonresponders.

Using the technique known as electrogastrography, we studied the postprandial response of gastric myoelectrial activity in subjects with type II diabetes. Seventy-one subjects with type II diabetes underwent 1 hr of fasting electrogastrography recording. HbA1c and fasting serum glucose levels were obtained. Subjects then underwent an additional 2 hr of electrogastrography recording in the post prandial state. Sixty of the 71 patients (85%) had gastric rhythm abnormalities in the fasting state. Forty-six of 71 subjects (65%) responded to the test meal by improving their electrogastrography tracings (responders) while 35% did not respond (nonresponders). The time spent in bradygastria during the fasting state by responders was 26.3+/-12.8% vs 10.9+/-8.5% for nonresponders (P < 0.0001). The percent tachygastria during the fasting state in responders was 19.8+/-13.0%, which was less than nonresponders (38.3+/-29.7%) (P < 0.001). Fasting plasma glucose and HbA1c could not be used to predict the gastric myoelectrical response to meal. In conclusion, gastric rhythm disturbances are common in type II diabetes; there was no correlation between HbA1c levels, age, duration of diabetes, or fasting serum glucose and gastric dysrhythmia in response to meal; two groups of subjects emerged: those who became less dysrhythmic in the post pradial state (responders) and those who did not (non-responders); and fasting bradygastria was associated with responders and fasting tachygastria was associated with nonresponders.

Diabetes Mellitus, Type 2↗
PubMed2001

Renal biopsy in pregnancies complicated by undetermined renal disease.

BACKGROUND: The aim of this retrospective study was to verify the role of renal biopsy in pregnancies complicated by renal dysfunction. METHODS: A series of 15 percutaneous renal biopsies performed in 15 pregnant women with renal disease presenting during pregnancy over the past 10 years (1990-1999) were reviewed. RESULTS: All the patients underwent renal biopsy before 30 weeks of gestation. The indications for renal biopsy were renal dysfunction of unknown cause or symptomatic nephrotic syndrome (NS). Patients with toxemia were excluded. Eight women had lupus nephritis, including five with diffuse crescenteric changes and three with a mesangial proliferative pattern. Three had chronic glomerulonephritis (CGN), two had mesangial proliferative glomerulonephritis and one each had diabetic nephrosclerosis and endocapillary proliferative glomerulonephritis. There were no significant complications except in one patient who experienced gross hematuria. Early induction of labor was recommended for the four patients with diabetic nephrosclerosis or CGM. The other 11 patients received intravenous pulse methylprednisolone or high dose oral prednisolone therapy. The responses to steroid therapy in these 11 patients were as follows: five achieved complete remission of NS, three achieved incomplete remission, and three achieved partial remission. After 2 years' follow-up, seven mothers achieved complete remission, three had died, three developed chronic renal failure (CRF), and two progressed to end stage renal failure (ESRF) requiring chronic hemodialysis. Fourteen of the 15 pregnancies resulted in live births and the other child was stillborn. CONCLUSIONS: Renal biopsy performed during pregnancy is not contraindicated. The results of histopathological studies are extremely useful in counseling regarding continuation or termination of pregnancy, potential maternal and fetal outcome, and recommending specific therapeutic modalities.

Adult↗
PubMed2001

Oral health and dental care in modern-day China.

The purpose of this paper is to present salient background information on the oral care situation and organization in China and to review epidemiological literature that has been published on adults in Chinese dental journals during the last 20 years as a context for understanding ongoing oral health research activities in China. Searches were conducted through Medline as well as Chinese language catalogues and around 30 Chinese dental journals. Most oral health surveys on adults were conducted after 1970 mainly on residents living in big cities, which are also the location of major medical universities. Surveys conducted among farmers were uncommon. Dental caries and periodontal disease were the major dental diseases studied. Only a few surveys on people's oral health knowledge, attitudes and behavior were conducted. Papers concerning dental treatment needs and utilization of dental services among adults were scarce. Sample size was usually not a major problem in these surveys but the sampling methods and diagnostic criteria used were often poorly defined. Mean DMFT scores between 2 and 6 were reported in the 35-44-year-olds and between 9 and 16 in the elderly younger than 75 years. Calculus and gingivitis were reported to be common in adult Chinese; the proportion of subjects with shallow and deep periodontal pockets was not high. Complete edentulousness in the 60-69-year-olds was usually reported to be less than 10%. About 14% of the 35-44-year-olds and 19% of the 65-74-year-olds did not brush their teeth daily.

China↗
PubMed2001

Interleukin-5 in growth and differentiation of blood eosinophil progenitors in asthma: effect of glucocorticoids.

1. There are increased numbers of circulating CD34(+) progenitor cells for eosinophils in patients with atopic asthma, with a further increase following allergen exposure or spontaneous worsening of asthma. We investigated the expression of IL-5 and IL-5Ralpha receptor in circulating CD34(+) progenitor cells in allergic asthmatics and the effects of corticosteroids. 2. Using double-staining techniques, up to 50% of CD34(+) cells expressed intracellular IL-5, and by RT - PCR, there was significant expression of IL-5 mRNA. When cultured in a semi-liquid methylcellulose medium, there were more eosinophil colony-forming units grown from asthmatic non-adherent mononuclear cell depleted of T cells in the presence of the growth factors GM-CSF, SCF and IL-3, but not of IL-5. 3. An anti-IL-5Ralpha receptor antibody and an anti-sense IL-5 oligonucleotide reduced the number of eosinophil colony forming units. No IL-5 mRNA or protein expression on T cells was observed in asthmatics or normal subjects. In the presence of growth factors including IL-5, there were significantly greater colony numbers with eosinophilic lineage grown from either asthmatics or normal subjects. 4. Dexamethasone (10(-6) M) suppressed IL-5 mRNA and protein expression in CD34(+) cells, and reduced eosinophil colony-forming units in asthmatics, but not in normal subjects. Dexamethasone did not change the expression of IL-5Ralpha on CD34(+) cells. 5. We conclude that there is increased expression of IL-5 on blood CD34(+) cells of patients with asthma and that this expression may auto-regulate eosinophilic colony formation from these progenitor cells. Corticosteroids inhibit the expression of IL-5 in circulating CD34(+) progenitor cells.

Adult↗
PubMed2001

Inhibition of prostacyclin by indomethacin ameliorates the splanchnic hyposensitivity to glypressin in haemorrhage-transfused common bile duct-ligated rats.

Prostacyclin (PGI2) is an important contributor to the mediation of hyporeactivity to vasoconstrictors and the development of hyperdynamic circulation in portal hypertensive states. Inhibition of PGI2 synthesis in haemorrhage-transfused partially portal vein-ligated rats could ameliorate the splanchnic hyposensitivity to glypressin, a long-acting vasopressin analogue. This study investigated whether the hyposensitivity to glypressin also exists in rats with common bile duct ligation (BDL) and whether the inhibition of PGI2 synthesis by indomethacin could potentiate the portal-hypotensive effect of glypressin in bleeding BDL rats. Two series of BDL rats were used. Series 1 investigated the haemodynamic effects of low dose glypressin (0.07 mg kg-1) in BDL rats with or without bleeding by catheterization. In series 2, haemodynamic parameters were measured in stable or bleeding BDL rats that were receiving intravenously high dose glypressin (0.2 mg kg-1) or indomethacin (5 mg kg-1) followed by high dose glypressin. In rats with a hypotensive haemorrhage, 4.5 mL of blood was withdrawn and 50% of the withdrawn blood was reinfused before the administration of glypressin or indomethacin. Splanchnic hyposensitivity to glypressin was demonstrated in haemorrhage-transfused BDL rats receiving high, but not low, doses of glypressin. Indomethacin infusion did not cause significant systemic and portal haemodynamic changes in bleeding BDL rats (P > 0.05). The addition of indomethacin significantly enhanced the portal-hypotensive effects of glypressin (P < 0.05) and potentiated the increases in mean arterial pressure induced by glypressin infusion (P < 0.001) in bleeding BDL rats. Splanchnic hyposensitivity to glypressin observed in haemorrhage-transfused BDL rats could be ameliorated by the addition of indomethacin, suggesting a role of endogenous PGI2 in its pathophysiology.

Animals↗
PubMed2001

Detrimental effects of nitric oxide inhibition on hepatic encephalopathy in rats with thioacetamide-induced fulminant hepatic failure.

Hepatic encephalopathy is a complex neuropsychiatric syndrome seen secondary to acute liver failure, chronic parenchymal liver disease, or portal-systemic anastomosis. Vasodilatation induced by nitric oxide (NO) may be involved in the development of hepatic coma. However, there are no comprehensive data concerning the effects of NO inhibition on the severity of hepatic encephalopathy. Male Sprague-Dawley rats weighing 300-350 g were used. Fulminant hepatic failure was induced by intraperitoneal injection of thioacetamide (TAA, 350 mg kg-1 day-1) for 3 days. Rats were divided into two groups to receive either NG-nitro-L-arginine methyl ester (L-NAME, 20 mg kg-1 day-1 via intragastric gavage) or normal saline (N/S) from 2 days prior to TAA administration for 5 days. Severity of encephalopathy was assessed by counts of motor activity and neurobehaviour test scores. Plasma levels of endotoxin, tumour necrosis factor-alpha and nitrate/nitrite were determined by the chromogenic Limulus assay, enzyme-linked immunosorbent assay and colorimetric assay, respectively. Compared with N/S-treated rats, the mortality rate was significantly higher in rats receiving L-NAME (59% vs. 18%, P < 0.01). Inhibition of NO had detrimental effects on the counts of motor activities (P < 0.05) and neurobehaviour score (P < 0.01). Rats treated with L-NAME had significantly higher plasma levels of endotoxin (26.7 +/- 3.8 pg mL-1) and tumour necrosis factor-alpha (29.4 +/- 6.5 pg mL-1) compared with rats treated with N/S (13.2 +/- 2.7 pg mL-1 and 11.2 +/- 2.6 pg mL-1, respectively, P < 0.01). Plasma levels of endotoxin and tumour necrosis factor-alpha, but not of nitrate/nitrite, were significantly correlated with the severity of hepatic encephalopathy (P < 0.05). Chronic L-NAME administration had detrimental effects on the severity of encephalopathy in TAA-treated rats, suggesting a protective role of NO in the development of fulminant hepatic failure.

Animals↗
PubMed2001

Molecular characterization of Bacillus anthracis using multiplex PCR, ERIC-PCR and RAPD.

AIMS: To investigate the molecular characterization of Bacillus anthracis strains by multiplex PCR, enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) and random amplification of polymorphic DNA (RAPD). METHODS AND RESULTS: Three primers were used to amplify the cya, cap and cereolysinAB genes in the multiplex PCR. Two distinct ERIC-PCR and RAPD fragments, which separated B. anthracis into two groups, were used as probes in Southern hybridization experiments. The probes hybridized only to the cya+ B. anthracis strains identified by the multiplex PCR. Nucleotide sequence analysis of the two cloned fragments showed they were from the pXO1 plasmid of B. anthracis. CONCLUSION: Multiplex PCR simultaneously identified isolates of the Bacillus cereus group and the B. anthracis virulence factors. ERIC-PCR and RAPD, combined with the Southern hybridization analyses, differentiated B. anthracis strains and separated them from the closely related B. cereus group bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: ERIC-PCR and RAPD assay could be effective in differentiating virulent from avirulent B. anthracis. Our results also show that the amplification of the large plasmids was allowed in the ERIC-PCR and RAPD assay.

Bacillus anthracis↗
PubMed2001

Endothelin-1 induces vasoconstriction on portal-systemic collaterals of portal hypertensive rats.

Portal hypertension is associated with increased hepatic and collateral resistance to an increased portal blood flow. Endothelin-1 (ET-1) can induce intrahepatic vasoconstriction and consequently increase portal pressure. It is unknown if ET-1 also modulates portal pressure by a direct vasoconstrictive effect on collaterals. This study investigated the collateral vascular responses to ET-1, the receptors in mediation, and the regulation of ET-1 action by nitric oxide and prostaglandin. The portal-systemic collaterals of partially portal vein-ligated rats were tested by in situ perfusion. The concentration-response curves of collaterals to graded concentrations of ET-1 (10(-10)-10(-7) mol/L) with or without BQ-123 (ET(A) receptor antagonist, 2 x 10(-6) mol/L), BQ-788 (ET(B) receptor antagonist, 10(-7) mol/L) or both were recorded. In addition, the collateral responses to ET-1 with preincubation of n(omega)-nitro-L-arginine (NNA; 100 mol/L), indomethacin (INDO; 10 mol/L), or in combination were performed. ET-1 increased the perfusion pressure of collaterals and its effect was significantly suppressed by BQ-123 alone and BQ-123 plus BQ-788, but not BQ-788 alone (P <.05). Incubation with NNA, INDO, or both significantly enhanced the response of collaterals to ET-1 (P < .05). These results show that ET-1 produces a direct vasoconstrictive effect on the collateral vessels of portal hypertensive rats. This effect is mediated by ET(A,) but not ET(B), receptors. Both nitric oxide and prostaglandin modulate the collateral vascular response to ET-1 and may therefore participate in the development and maintenance of portal hypertension.

Animals↗
PubMed2001

A new "sandwich" method of combined endoscopic variceal ligation and sclerotherapy versus ligation alone in the treatment of esophageal variceal bleeding: a randomized trial.

BACKGROUND: Variceal ligation is the optimum endoscopic method for treating esophageal variceal bleeding. However, both early and multiple recurrences of esophageal varices frequently follow ligation. The aim of this randomized study was to determine whether a new, combined endoscopic "sandwich" method (i.e., ligation-sclerotherapy-ligation) could achieve better results than ligation alone. METHODS: Ninety-four patients with cirrhosis and acute or recent esophageal variceal bleeding were randomized to undergo either the "sandwich" method or ligation alone (47 patients in each group). RESULTS: The sclerosant was retained in the varices for more than 30 minutes in 7 of 8 patients undergoing the "sandwich" method plus radiographic contrast medium. Active bleeding was controlled with this new method (9/9) as efficiently as ligation (12/12). The rate of recurrent bleeding was similar for both methods. Multivariate analysis showed the necessity for the use of antibiotics (odds ratio 3.95: 95% CI [1.60, 9.76]) to be an independent factor for recurrent bleeding. Two patients in the "sandwich" group developed strictures, but the frequency of other complications did not differ between the 2 groups. Kaplan-Meier analysis showed the cumulative probability of variceal recurrence was lower with the "sandwich" method (p = 0.0391). The survival rate and causes of death were similar in both groups. CONCLUSIONS: The "sandwich" method leads to longer retention of sclerosant in varices. This method is superior to ligation alone in terms of lower variceal recurrence rate and comparable to ligation with respect to hemostasis. However, it is unknown whether the lower recurrence rate of varices will persist long-term.

Combined Modality Therapy↗
PubMed2001

Feasibility and potential benefit of maintenance endoscopic variceal ligation in patients with unresectable hepatocellular carcinoma and acute esophageal variceal hemorrhage: a controlled trial.

BACKGROUND: Patients with unresectable hepatoma and acute esophageal variceal bleeding have extremely high rates of recurrent bleeding and mortality. This controlled study evaluates the feasibility and potential benefit of maintenance endoscopic variceal ligation in these patients. METHODS: Patients with unresectable hepatoma and acute esophageal variceal bleeding underwent emergent endoscopic variceal ligation. After hemostasis, patients were randomized to undergo maintenance or esophageal variceal ligation (EVL) as necessary (demand ligation). RESULTS: Fifty-four patients underwent maintenance EVL and 55 demanded EVL. One or more subsequent EVL session could be performed in only 30 patients (55.6%) in the maintenance group (actual maintenance ligation). Logistic regression analysis found that hepatic function determines the feasibility of maintenance ligation (Child-Pugh's A+B vs. C, OR 23.00: 95% CI [5.26, 100.66]). The survival and recurrent bleeding rates were similar in both groups. A subgroup analysis of patients with Child-Pugh's A and B hepatic reserve in both the maintenance EVL group (n = 24) and demand EVL group (n = 25) was performed to assess the potential benefit of maintenance ligation. Maintenance ligation reduced the rate of recurrent bleeding compared with demand ligation (p = 0.043). Cox regression showed that portal vein thrombosis and tumors in both hepatic lobes were also factors together with EVL that determined recurrence of bleeding. Survival was similar in both groups. CONCLUSIONS: Maintenance ligation is feasible in patients with unresectable hepatoma and variceal hemorrhage if they have a good hepatic reserve. Maintenance ligation might lower the rate of recurrent bleeding in this subgroup of patients.

Acute Disease↗