PubMed Health⌕ Search

Biomedical subjects

J T Lin

Publications and source records attributed to J T Lin.

At least 163 records · Page 9Linked to original sources
PubMed1993

Circulating beta-atrial natriuretic factor in congestive heart failure in humans.

BACKGROUND: beta-Atrial natriuretic factor (beta-ANF) is an antiparallel dimer of alpha-ANF (alpha-ANF) with diminished cyclic GMP generation in vitro. To date, the presence of beta-ANF in the circulation of humans with severe congestive heart failure (CHF) remains controversial. The current study was designed to determine the presence and magnitude of circulating beta-ANF in severe CHF, to correlate plasma beta-ANF with the degree of ventricular dysfunction, and to investigate the role of human plasma and atrial tissue in the degradation of beta-ANF. METHODS AND RESULTS: Venous plasma samples were obtained from patients (n = 12) with severe CHF and normal volunteers (n = 8). Total plasma ANF was measured by radioimmunoassay. alpha-ANF and beta-ANF in nonextracted plasma were separated by gel filtration chromatography using a P-6 column. Right atrial tissue samples (n = 5) were collected from a different group of patients at the time of open-heart surgery. 125I beta-ANF and I125 ANF were incubated with atrial tissue or plasma. The corresponding peak areas of beta-ANF were determined by Tamaya Digital Planimeter. beta-ANF represented 61% of total plasma ANF in CHF patients and was not detected in normal human plasma. The elevation of beta-ANF correlated with the severity of ventricular dysfunction. Thirty percent of beta-ANF and 100% alpha-ANF were converted to smaller peptide fragments in atrial tissue no conversion in plasma. CONCLUSIONS: beta-ANF is the principal form of circulating ANF in patients with severe CHF and correlates with the degree of left ventricular dysfunction. beta-ANF is not generated from alpha-ANF and may be degraded rapidly in atrial tissue to smaller peptide fragments that do not occur in plasma. As beta-ANF is reported to have reduced biological action, the current studies may support the conclusion that the ANF system in CHF has reduced functional activity despite increases in circulation concentrations.

Aged↗
PubMed1993

Helicobacter pylori infection in a randomly selected population, healthy volunteers, and patients with gastric ulcer and gastric adenocarcinoma. A seroprevalence study in Taiwan.

To investigate the association of Helicobacter pylori and gastric ulcer and adenocarcinoma, IgG antibodies against H. pylori were examined in 823 randomly selected subjects, 92 healthy volunteers, 117 patients with gastric ulcer, and 148 with gastric adenocarcinomas in Taiwan, where the prevalence of gastric adenocarcinoma is high. The seropositivity of this population in Taiwan was 54.4%. Gastric ulcer patients had a higher seropositivity (83.8%) than healthy volunteers (62.0%) and gastric adenocarcinoma patients (62.2%) (P < 0.001). Gender difference, blood type, and habit of smoking were not associated with the seroprevalence in any study groups. Gastric ulcer coexistent with duodenal ulcer had a higher seropositivity (94.7%) (P < 0.05). The seropositivity of H. pylori in gastric adenocarcinoma patients was higher than in healthy volunteers only in younger age and was not associated with histologic type, invasion, and location of major tumors. The results reemphasize the association of H. pylori infection with gastric ulcer but not with gastric adenocarcinoma in Taiwan.

Adenocarcinoma↗
PubMed1993

Decreased polyglutamylation of methotrexate in acute lymphoblastic leukemia blasts in adults compared to children with this disease.

We compared blast cells from adult and pediatric patients with untreated acute lymphoblastic leukemia (ALL) (as separated groups of T-lineage cell and B-lineage cell ALL) to determine if methotrexate (MTX) polyglutamate formation in adult patients might be a contributing cause to the known difference in clinical outcome, since MTX is a key drug in chemotherapy regimens. Adult B-lineage cell ALL blasts and blasts from the patients with T-lineage cell ALL accumulated lower amounts of total MTX and polyglutamates, especially long-chain MTX polyglutamates (glu3-6) than pediatric B-lineage cell ALL blasts. In view of the importance of polyglutamylation of MTX as a determinant of cytotoxicity of this drug, decreased formation of MTX polyglutamates is likely a contributing cause to the lower cure rate in adult ALL and T-lineage cell ALL as compared to childhood B-lineage cell ALL.

Adult↗
PubMed1993

Serum levels of pepsinogen I in healthy volunteers and patients with gastric ulcers and gastric carcinoma in Taiwan.

In order to investigate the clinical usefulness of human pepsinogen I (PGI) as a noninvasive diagnostic tool for gastric lesions, 92 healthy volunteers, 87 patients with a gastric ulcer and 94 patients with gastric carcinoma, verified by histologic examinations, were enrolled. The serum level of PGI in each patient was measured by radioimmunoassay. Mean serum PGI levels were 95.4 +/- 39.4 ng/mL in patients with gastric ulcers, 77.6 +/- 29.3 ng/mL in healthy volunteers, and 52.1 +/- 26.5 ng/mL in patients with gastric carcinoma. Statistically significant differences (p < 0.01) existed between the two groups. Various factors which affect serum PGI levels, including age, sex, smoking habit, blood type, and Helicobacter pylori (H. pylori) infection, were also analyzed in each group. The serum levels of PGI were not affected by gender or blood type in any of the three groups (p > 0.05). A negative correlation of serum PGI levels with age was observed in patients with carcinoma (r = -0.43, p < 0.01). Smokers in the gastric ulcer group had significantly higher levels of PGI than nonsmokers (106.2 +/- 35.9 ng/mL vs 83.2 +/- 32.3 ng/mL, p < 0.05). A significantly higher PGI concentration was found in both H. pylori infected asymptomatic volunteers and gastric carcinoma patients (82.9 +/- 29.8 ng/mL vs 67.6 +/- 26.0 ng/mL, and 56.5 +/- 26.7 ng/mL vs 43.6 +/- 24.3 ng/mL, p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

Somatostatin-containing carcinoid tumor of the duodenum in neurofibromatosis: report of a case.

We report a case of von-Recklinghausen's disease presenting with obstructive jaundice and found to have a somatostatin-containing carcinoid tumor in the papilla of Vater and a small neurofibroma in the duodenum. A 42-year-old woman with von-Recklinghausen's disease presented with intermittent jaundice, pruritus, and mild steatorrhea of a two-year duration. Abdominal ultrasonography and computed tomography showed dilated intrahepatic ducts, common bile duct and pancreatic ducts. Duodenoscopy showed a tumor at the papilla of Vater, but a preoperative biopsy failed to provide a definite diagnosis. Laparotomy revealed a yellowish tumor at the papilla of Vater and another nodule on the mesenteric side of the second section of the duodenum. Microscopically, the tumor at the papilla of Vater was found to be a somatostatin-containing carcinoid tumor. The small nodule on the mesenteric side was a neurofibroma. The jaundice, pruritus and steatorrhea disappeared after surgery.

Adult↗
PubMed1993

Benign villous adenomas of the ampulla of Vater: report of two cases.

Benign tumors of the ampulla of Vater are uncommon. We report on two patients with epigastralgia, jaundice and pancreatitis caused by villous adenoma of the ampulla of Vater, combined with biliary tract stones, who were treated at National Taiwan University Hospital. Definite diagnoses were made by endoscopic retrograde cholangiopancreatography and biopsy. Their medical unsuitability for radical pancreaticoduodenectomy led us to revive the procedure of wide local excision of these tumors with reimplantation of the pancreatic duct and double sphincteroplasty. Operative time and blood loss were substantially less, and postoperative recovery was relatively uncomplicated. Hepatic resection for intrahepatic stones was performed later in the first case. Postoperative follow-up at 2.5 years showed no tumor recurrence. We suggest that local resection of benign ampullary tumors with double sphincteroplasty is the procedure of choice in high-risk patients.

Adenoma, Villous↗
PubMed1993

Secular changes in the clinical manifestation and pathologic pattern of early gastric cancer in Taiwan.

To investigate whether there has been a time trend change in the percentage of early gastric cancer to gastric cancer and the clinicopathologic features of early gastric cancer in Taiwan, we reviewed 208 patients diagnosed between 1964 and 1992. Patients were divided into group I from 1964-1980 (n = 106) and group II from 1981-1992 (n = 102). The percentage of early gastric cancer among total gastric resections in group II (14.7%) did not differ from group I (12.7%; p = 0.19). Epigastralgia (58.2%) was the most common complaint; 11.8% (12/102) of cancers in group II were incidentally detected by endoscopy. Endoscopy provided a better diagnostic aid than did radiology. Tumors were frequently located in the antrum (50.9%) with a mean diameter of 2.8 cm. Small cancers of less than 1 cm in diameter were more prevalent in group II (37.3%) than group I (10.4%; p < 0.001). Cancers of the elevated type (17.8%) were uncommon in contrast to depressed ones (82.2%; p < 0.001). The frequency of mucosal carcinoma (51.0%) was similar to submucosal carcinoma (49.0%). Mucosal carcinoma had less lymph node metastases (3.1%) than submucosal carcinoma (12.2%; p < 0.05) with an overall frequency of metastases of 7.5% (14/186). The five-year survival rate of group I (91.7%) was not statistically different from group II (94.6%). We concluded that, except for the symptomatology and the ability to diagnose, the clinicopathologic features of early gastric cancer were similar between these two time periods. Repeated investigation of suspicious lesions and endoscopic screening on asymptomatic subjects may increase the rate of detection and thus guarantee a favorable outcome.

Adult↗
PubMed1993

Effects of neuroactive agents on the isolated heart activities of marine bivalve Meretrix lusoria.

By recording method, we measured simultaneously both the contractile force (CF) and the action potential (AP) of the isolated heart to confirm the chief cardioregulatory transmitters of a marine bivalve. The effects of several neuroactive agents on CF, HR and the amplitude of AP in marine bivalve were investigated. Acetylcholine and carbachol produced inhibitory effects on the heart performance at 1.0 x 10(-11) M. Choline also exhibited inhibitory effects at a higher concentration, but atropine, curare, pilocarpine and hexamethonium bromide (all at 1.0 x 10(-4) M) exerted no significant effects on the spontaneous cardiac activities. 5-HT and 8-OH-DPAT produced positive chronotropic and inotropic effects on the heart at 1.0 x 10(-8) M, whereas adrenaline and dopamine were positively inotropic at 1.0 x 10(-5) M. The perfusion of adrenaline or dopamine typically prolonged the plateau duration of the action potential, and then enhanced CF. However, histamine, GABA and PGF2 alpha all exerted no significant effect on either CF or the amplitude of AP of the isolated heart. The results indicate that 5-HT and acetylcholine are excitatory and inhibitory agents, respectively, that regulate the isolated cardiac performance in a marine bivalve. The mechanism of positively inotropic effects of biogenic amines is discussed.

Acetylcholine↗
PubMed1993

Hepatic lymphoma mimicking liver abscess: report of a case and review of the literature.

Early detection of hepatic lymphoma involvement is of prime importance, as it affects the choice of treatment and the prognosis. However, clinical recognition of these lesions at the time of initial staging or during the course of the disease is difficult because infiltration by lymphoma is usually diffuse rather than focal. We describe a 64-year-old man with a previous history of peripheral T-cell lymphoma involving the lung, skin and inguinal lymph nodes. After six months of chemotherapy resulting in a complete clinical remission, he suffered from an intermittent fever and right upper quadrant pain one week prior to admission. Abdominal ultrasonography and computed tomography disclosed a 6.0 x 5.7 cm heterogeneous mass in the liver. The serum alfafetoprotein level was within the normal limits and an indirect hemagglutinin titer for ameba was negative. The patient was initially treated for a liver abscess until a liver biopsy showed malignant lymphoma. Chemotherapy was initiated and the tumor was remarkable reduced in size, with a final dimension of 2.3 x 2.2 cm before discharge. radiologic patterns of hepatic lymphoma and its differential diagnosis are discussed in this report.

Diagnosis, Differential↗
PubMed1993

Hematuria due to nutcracker phenomenon of left renal vein: report of a case.

The nutcracker phenomenon refers to compression of the left renal vein between the aorta and the superior mesenteric artery, which leads to painless intermittent gross hematuria. An 11-year-old girl presented with a two-year history of recurrent painless hematuria. Physical examination and routine laboratory examinations were noncontributory. Renal ultrasonographic study, selective left renal angiography and retrograde left renal venography showed evidence of compression of the left renal vein where it crossed between the aorta and the superior mesenteric artery. A needle biopsy of the right kidney revealed no abnormal histologic change. These results led to a diagnosis of the nutcracker phenomenon; to the best of our knowledge, this may be the first case reported in Taiwan. Herein, we present our experience with this case and discuss the diagnostic options.

Angiography, Digital Subtraction↗
PubMed1993

Helicobacter pylori infection in early and advanced gastric adenocarcinoma: a seroprevalence study in 143 Taiwanese patients.

The association between gastric adenocarcinoma and Helicobacter pylori infection remains controversial. A seroprevalence study of Helicobacter pylori infection in 143 patients with gastric adenocarcinoma and a control group of 823 subjects randomly selected from four areas in Taiwan, was carried out to elucidate the association. The overall seropositivity of Helicobacter pylori in gastric adenocarcinoma patients (62.9%) was higher than in controls (54.4%), but the difference was not statistically significant (p > 0.05). The seropositivity of early gastric adenocarcinoma (61.5%) was not significantly different from that of advanced gastric adenocarcinoma (63.2%). Various demographic factors such as sex, blood type, cigarette smoking, tumor histology and location were not associated with the seroprevalence of Helicobacter pylori. The age-specific seroprevalence of Helicobacter pylori tended to be higher in younger patients and decreased after the age of 60 years in gastric adenocarcinoma, in contrast to a stepwise increase of seropositivity in controls. This suggests that Helicobacter pylori infection in early life may be a contributory factor in gastric carcinogenesis.

Adenocarcinoma↗
PubMed1993

Serum levels of pepsinogen I and gastrin in gastric carcinoma: the influence of Helicobacter pylori infection and tumor characteristics.

The influence of Helicobacter pylori infection on serum levels of pepsinogen I and gastrin in gastric carcinoma was investigated by simultaneous determination of serum pepsinogen I, gastrin, and IgG antibodies against Helicobacter pylori in 100 patients with gastric carcinoma, and in another 100 age- and sex-matched healthy controls. Serum pepsinogen I level was significantly lower in gastric carcinoma than in controls (55.5 +/- 28.1 vs. 76.9 +/- 25.1 ng/ml, p < 0.005), but there was no difference in serum gastrin between them (63.2 +/- 30.2 vs. 57.4 +/- 28.5 pg/ml, p = 0.16). Helicobacter pylori infection caused a significant increase in serum PGI level in advanced, intestinal type, and non-cardia gastric carcinoma. The serum gastrin level was affected by neither Helicobacter pylori infection nor any of the tumor characteristics. It is concluded that pepsinogen I, rather than gastrin, in the serum is greatly influenced by Helicobacter pylori infection and tumor characteristics in gastric carcinoma.

Adult↗
PubMed1992

Activation of neuromedin B-preferring bombesin receptors on rat glioblastoma C-6 cells increases cellular Ca2+ and phosphoinositides.

Recent cloning studies confirm the presence of two subtypes of bombesin (Bn) receptors. In contrast to the gastrin-releasing peptide (GRP)-preferring subtype, which has been widely studied, nothing is known about the cellular mechanisms of the neuromedin B (NMB)-preferring subtype, which occurs widely in the central nervous system and gastrointestinal tissues, partially because of the lack of a cell line with functional receptors. In the present study we have investigated Bn receptors on the rat glioblastoma cell line C-6, reported to contain mRNA of the NMB receptor subtype. Binding of 125I-[D-Tyr0]NMB to these cells was time- and temperature-dependent, saturable, reversible, and only inhibited by Bn receptor agonists or antagonists. For Bn receptor agonists the relative potencies were: NMB (1.7 nM) approximately equal to litorin (3 nM) greater than ranatensin (8 nM) greater than Bn (19 nM) greater than neuromedin C (NMC) (210 nM) greater than GRP (500 nM). These relative affinities were almost identical to those for the NMB receptor subtype on rat oesophageal tissue and for Balb 3T3 cells stably transfected with the NMB receptor subtype. These potencies differed from those for the GRP receptor subtype on rat pancreatic acini [Bn approximately equal to litorin (4 nM) greater than ranatensin, NMC, GRP (15-20 nM) much greater than NMB (351 nM)]. The relative potencies of four different classes of Bn receptor antagonists were compared. Results from C-6 tumour cells agreed closely with those for binding to the NMB receptor subtype on rat oesophageal tissue and in Balb 3T3 cells stably transfected with this receptor, and differed markedly from those for binding to the GRP receptor subtype on rat pancreatic acini. Four Bn receptor antagonists had a higher affinity for the GRP subtype ([D-Phe6]Bn-(6-13)ethyl ester (500 x), [D-Phe6][psi 13-14,Cpa14]Bn- (6-14) (70 x) (where psi 13-14 refers to the replacement of the -CONH- peptide bond between Leu13 and Met14 by -CH2NH2) [psi 13-14,Leu14]Bn, [D-Phe6]Bn-(6-13) propylamide (30 x)] and two had a higher affinity for the NMB subtype on C-6 cells and transfected cells ([D-Pro4,D-Trp7,9,10] substance P-(4-11) (9 x) and [Tyr4,D-Phe12]Bn (18 x)]. In C-6 tumour cells, Bn receptor agonists caused an increase in cytosolic Ca2+ and the generation of inositol phosphates. For both responses, NMB was more than 50-fold more potent than GRP. Neither NMB nor GRP increased cyclic AMP. These results demonstrate that the rat glioblastoma cell line C-6 possesses functional NMB-preferring Bn receptors, and agonist occupation activates phospholipase C, thus increasing cytosolic Ca2+ and inositol phosphate formation. Because the interaction of Bn-related peptides with C-6 cell receptors is identical with that reported in other tissues containing the mRNA for the NMB subtype, this cell line should prove useful in exploring further the cellular basis of action of the peptides that interact with this receptor in the central nervous system and various other tissues.

3T3 Cells↗
PubMed1992

Intrinsic resistance to methotrexate in human soft tissue sarcoma cell lines.

A human fibrosarcoma cell line, HT-1080, and four new cell lines (HS-16, HS-28, HS-30, and HS-42) were established from untreated patients with mesenchymal chondrosarcoma, peripheral nerve sheath sarcoma, malignant hemangiopericytoma, and mixed mesodermal tumor, respectively, and were used for analysis of mechanisms of intrinsic resistance to methotrexate. All four new cell lines were resistant to methotrexate as determined by inhibition of thymidylate synthase in whole cells and by growth inhibition, as compared with HT-1080, a methotrexate sensitive cell line. Methotrexate uptake, level of dihydrofolate reductase, and inhibition of this enzyme by methotrexate in the four cell lines were comparable to HT-1080 cells. However, levels of long chain polyglutamates (glu3-5) of methotrexate achieved after a 24-h incubation with this drug were much lower in the four new cell lines as compared to the HT-1080 cell line (5- to 20-fold lower). The low levels of methotrexate polyglutamates formed is likely the major cause of intrinsic methotrexate resistance in these new sarcoma cell lines.

Drug Resistance↗
PubMed1992

Mechanisms of natural resistance to antifolates in human soft tissue sarcomas.

Efforts to use fresh human sarcoma cells for evaluating antifolate resistance with an in situ thymidylate synthesis assay using 5-[3H] deoxyuridine were unsuccessful because of low thymidylate synthesis activity in enzymatically disaggregated tumors. By incubating tumor cell suspensions in supplemented RPMI-1640 medium with 10% fetal bovine serum for 3 days, activity of the in situ thymidylate synthesis assay markedly increased (1.42 versus 0.03 pmol/h/10(7) cells), thus allowing 75% of samples to be evaluated for antifolate sensitivity. By criteria developed with a methotrexate-resistant and -sensitive cell line, this assay indicated that most sarcomas are naturally resistant to methotrexate (12 of 15). Natural resistance to 10-ethyl-10-deazaaminopterin and trimetrexate was also observed in 60% of the samples (nine of 15, respectively). The results from the 3-day in situ assay were confirmed by specific tests for resistance mechanisms in most sarcoma samples. The resistance mechanisms detected were impaired polyglutamylation, an increased level of dihydrofolate reductase, and amplification of this gene. These results encourage further exploration of this assay to predict response to antifolates in individual patients and to evaluate efficacy of new antifolates as candidates for clinical trial.

Aminopterin↗
PubMed1992

Hepatitis C virus RNA in saliva of patients with posttransfusion hepatitis and low efficiency of transmission among spouses.

In a prospective study of posttransfusion hepatitis, 14 patients who were diagnosed with posttransfusion hepatitis C were enrolled randomly for the study of hepatitis C virus (HCV) RNA in saliva. Saliva and serum samples were collected on the same day. Spouses of 11 married patients were also tested for anti-C100 and HCV RNA. Paired serum and saliva samples were tested for HCV RNA by a nested polymerase chain reaction (PCR). Two primer pairs specific for the non-coding region of HCV were used for the PCR and a oligonucleotide sequence between the primers was used as the probe for Southern hybridization. Six patients were positive for HCV RNA by first round PCR amplification and an additional four patients were detected after second round PCR. All patients were negative for HCV RNA in saliva after first round PCR, while seven were positive after second round PCR amplification. All seven patients were positive for HCV RNA in paired serum samples. HCV RNA was detectable in saliva from 1 week to 38 months after the onset of hepatitis. All spouses were negative for anti-C100 and HCV RNA. We conclude that HCV RNA is present in the saliva of approximately half of patients with acute and chronic hepatitis C, and the presence of HCV RNA correlates with HCV viremia. The efficiency of HCV transmission is low among spouses.

Adult↗
PubMed1992

Posttransfusion hepatitis revisited by hepatitis C antibody assays and polymerase chain reaction.

Sera of 40 patients with posttransfusion non-A, non-B hepatitis were tested for hepatitis C and B viral genomes by polymerase chain reaction and for hepatitis C antibodies by synthetic peptide immunoassays. Five were then considered to have chronic hepatitis before transfusion. Six patients without hepatitis C markers and hepatitis B virus DNA recovered. In 29 recipients who became positive for hepatitis C virus RNA, posttransfusion hepatitis C was diagnosed. Of them, 5 were hepatitis B surface antigen carriers. Synthetic peptide immunoassays detected 28 whereas anti-C100 assay detected 23 of the 29 acute hepatitis C patients. Anticapsid antibody appeared earlier than the antinonstructural antibody in 10 seroconverters. They appeared simultaneously in 15 seroconverters but anticapsid antibody appeared later then the antinonstructural antibody in 3 hepatitis B carriers. Transient suppression of hepatitis B surface antigenemia was found in 2, whereas elevated hepatitis B virus DNA was found in 3 carriers during acute hepatitis C superinfection. In 2 carriers whose hepatitis C became chronic, both hepatitis B and C viral genomes persisted throughout 2 years of followup. Therefore these assays define posttransfusion hepatitis C more precisely, and there seems no significant interference between chronic hepatitis B and C virus infections.

Adult↗