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Biomedical subjects

J H Yang

Publications and source records attributed to J H Yang.

At least 73 records · Page 4Linked to original sources
PubMed1998

Pheochromocytoma complicated with cardiomyopathy after delivery--a case report and literature review.

Pheochromocytoma in pregnancy is very rare but it is associated with very high maternal and fetal mortality. Therefore, it is important to include pheochromocytoma in the differential diagnosis of hypertension associated with pregnancy. It is difficult to make a diagnosis of pheochromocytoma in pregnancy before delivery. The characteristic symptoms of pheochromocytoma could be initiated during delivery because the process of delivery, general anesthesia, fetal movement, induce acute surge of catecholamine release, which could also induce cardiomyopathy. Early diagnosis and intensive care can affect the prognosis of cardiomyopathy induced by pheochromocytoma. Proper management with alpha-blockade, beta-blockade and angiotension converting enzyme inhibitor could acutely reverse the course of cardiomyopathy.

Adrenal Gland Neoplasms↗
PubMed1998

The aryl hydrocarbon receptor interacts with transcription factor IIB.

The aryl hydrocarbon receptor (AHR) and its DNA binding partner, the AHR nuclear translocator (ARNT), are basic helix-loop-helix transcription factors that mediate many of the toxic and carcinogenic effects of polyhalogenated aromatic hydrocarbons. The basic regions of the AHR and ARNT contact the GCGTG recognition site, whereas both their helix-loop-helix domains and periodicity-ARNT-single-minded domains participate in heterodimerization. To delineate the transcription factors that may facilitate DNA binding and transcriptional activation of the AHR/ARNT heterodimer, we questioned whether transcription factor IIB (TFIIB) may interact with either the AHR or ARNT and whether this interaction may affect the ability of the AHR/ARNT complex to bind DNA. Coaffinity precipitation assays demonstrated that both the AHR and ARNT were capable of interacting with TFIIB. Domain mapping experiments revealed that TFIIB interacts with the periodicity-ARNT-single-minded and carboxyl-terminal regions of the AHR. To determine whether the interaction between TFIIB and the AHR may affect DNA binding of the AHR and ARNT complex, we performed gel shift experiments in the absence and presence of TFIIB. The addition of TFIIB significantly increased the formation of the AHR/ARNT DNA binding complex, but only if TFIIB was first allowed to interact with the AHR before the addition of ARNT. These results indicate that TFIIB interacts with the AHR and may stabilize the DNA binding form of the AHR and thereby augment the ability of the AHR/ARNT complex to interact with its DNA recognition site.

Aryl Hydrocarbon Receptor Nuclear Translocator↗
PubMed1998

Controlled ovarian hyperstimulation and intrauterine insemination in subfertility. How many treatment cycles are sufficient?

OBJECTIVE: To examine the combined effects of factors influencing the pregnancy rates following controlled ovarian hyperstimulation (COH) and intrauterine insemination (IUI). STUDY DESIGN: After utilizing the couple as the unit of analysis, 416 couples undergoing COH and IUI with the husband's sperm were studied retrospectively. RESULTS: The woman's age, postwash total motile sperm counts and number of IUI treatment cycles were three major factors that affected the results of IUI. The predicted cumulative pregnancy rates under different values of the above three factors were therefore calculated using multiple logistic regression analysis and were compared to the pregnancy rate achieved by a cycle of in vitro fertilization and tubal embryo transfer. CONCLUSION: Three treatment cycles of IUI are optimal for women aged < or = 34 with postwash total motile sperm counts > 5 x 10(6). For women either aged > or = 35 or with postwash total motile sperm counts < 5 x 10(6), the cumulative pregnancy rates achieved by IUI are extremely low, and other means of assisted reproduction are recommended for couples in those categories. However, this conclusion pertains to our clinics, and other institutions should establish their own data.

Adult↗
PubMed1997

Purification and characterization of a human RNA adenosine deaminase for glutamate receptor B pre-mRNA editing.

The glutamate receptor subunit B (GluR-B) pre-mRNA is edited at two adenosine residues, resulting in amino acid changes that alter the electrophysiologic properties of the glutamate receptor. Previous studies showed that these amino acid changes are due to adenosine to inosine conversions in two codons resulting from adenosine deamination. Here, we describe the purification and characterization of an activity from human HeLa cells that efficiently and accurately edits GluR-B pre-mRNA at both of these sites. The purified activity contains a human homolog of the recently reported rat RED1 (rRED1) protein, a member of the family of double-stranded RNA-dependent deaminase proteins. Recombinant human RED1 (hRED1), but not recombinant dsRAD, another member of the family, efficiently edits both the Q/R and R/G sites of GluR-B RNA. We conclude that the GluR-B editing activity present in HeLa cell extracts and the recombinant hRED1 protein are indistinguishable.

Adenosine↗
PubMed1997

Tumors of the orbit. Pitfalls of the surgical approach in 37 children with orbital tumor.

The authors review their experience with 37 children with orbital tumors, summarizing their surgical techniques, the indications applied, and the pitfalls of each surgical approach. Tumors located in the retro-ocular or intraorbital space were surgically excised through a transcranial approach (28 cases), while for tumors in other sites lateral orbitotomy (5 cases), medial orbitotomy (1 case) and biopsy (3 cases) were performed. A transcranial approach was used for tumors with intracranial extension and for those located in the orbital apex and deep medial orbital compartment. Lateral orbitotomy was used for tumors located in the superior, temporal or inferior compartment of the orbit and those in the lateral apex. A medial orbitotomy was used for tumors located medial to the optic nerve. Outcomes of the surgical intervention varied, depending on the pathology, location and extent of the individual tumors. To obtain optimal exposure and minimize functional deficits, the pitfalls of surgical approaches to orbital tumors are discussed.

Adolescent↗
PubMed1997

Intravenous albumin does not prevent the development of severe ovarian hyperstimulation syndrome.

OBJECTIVE: To determine the efficacy of IV albumin in the prevention of severe ovarian hyperstimulation syndrome (OHSS). DESIGN: Prospective study group with historical control. SETTING: University hospital-based IVF program. PATIENT(S): Between 1993 and 1995, 42 consecutive patients undergoing IVF-ET or tubal ET who had serum E2 levels > or = 3,600 pg/mL (conversion factor to SI unit, 3.671) on the day of hCG administration and/or > or = 20 oocytes retrieved were considered at high risk for severe OHSS and were selected as the control group. From December 1995 to October 1996, IV albumin was given to 30 consecutive patients who fulfilled these criteria. INTERVENTION(S): The treatment group received IV albumin after oocyte retrieval. MAIN OUTCOME MEASURE: Occurrence of severe OHSS. RESULT(S): None of the 16 patients in the treatment group in nonconception cycles developed severe OHSS, compared with 5 (21.7%) of 23 in the control group. In conception cycles, 4 (28.6%) of 14 patients in the treatment group developed severe OHSS, compared with 9 (47.4%) of 19 in the control group. All 4 patients with multiple pregnancies in the treatment group developed severe OHSS, compared with 3 (60%) of 5 in the control group. None of the 10 patients with singleton pregnancies in the treatment group developed severe OHSS, compared with 6 (42.9%) of 14 in the control group. CONCLUSION(S): Intravenous albumin prevents severe OHSS in high-risk patients who did not conceive or who carried singleton pregnancies, but not in the patients with high-order pregnancies.

Adult↗
PubMed1997

Characterization of glutamate transporter function in the tiger salamander retina.

Glutamate transporters in the tiger salamander retina were studied by autoradiographic and intracellular recording techniques. When the retina was incubated with 15 microM L-[3H]glutamate, photoreceptors and Muller cells were labeled, indicating that these cells had high-affinity glutamate uptake transporters. A much higher dose of glutamate than kainate was required in the bath to produce the same membrane depolarization in horizontal cells (HCs), and the time course of glutamate-induced depolarization was much slower than that of the kainate-induced depolarization. Since glutamate is a substrate of glutamate transporters whereas kainate is not, we attribute these differences to the buffering of extracellular glutamate by glutamate transporters in the retina. D-aspartate (D-asp) increased the efficacy of bath-applied glutamate. Dihydrokainate (DHKA) exerted little effect on glutamate efficacy when applied alone, but it increased glutamate efficacy in the presence of D-asp. These results are consistent with the notion that glutamate transporters in Muller cells are D-asp sensitive and those in photoreceptors are DHKA and D-asp sensitive. Application of DHKA (1-2 mM) did not affect the dark membrane potential or the light responses in rods and cones, but it depolarized the HC dark membrane potential and reduced the HC peak and tail light responses. Our results suggest that DHKA-sensitive glutamate transporters in photoreceptors regulate glutamate levels in rod and cone synaptic clefts. They modulate dark membrane potential and the relative rod cone inputs in retinal HCs.

ATP-Binding Cassette Transporters↗
PubMed1997

Rupioid psoriasis associated with arthropathy.

We reported a rare case of rupioid psoriasis associated with arthropathy. A 28-year-old male had suffered from severe arthritis for 6 months and had limpet-like, cone-shaped skin lesions on the extremities for 3 months. The histopathology revealed remarkable Munro's and Kogoj microabscesses, intense dermal edema, and moderate inflammatory cell infiltration. The radiological examination showed bilateral sacroilitis. The skin lesions and arthritis responded dramatically in three weeks to i.m. methotrexate combined with topical steroids and emollients and occlusive dressing technique. There was no recurrence of such skin lesions during the two year follow-up period.

Abscess↗
PubMed1997

Long GnRH-agonist protocol in an IVF program. Is it appropriate for women with normal FSH levels and high FSH/LH ratios?

OBJECTIVE: To determine whether subjects with an elevated ratio of follicle-stimulating hormone (FSH) to luteinizing hormone (LH) but normal basal FSH levels should be regarded as poor responders to controlled ovarian hyperstimulation. STUDY DESIGN: One hundred twenty-five women undergoing in vitro fertilization (IVF) for the first time were recruited in this retrospective cohort study. Women over 40 years old or having serum basal FSH > 10 mIU/mL were excluded. RESULTS: Various cutoff values for the FSH/LH ratio were chosen, and the ratio demonstrated that pregnancy rates were apparently higher in patients with the long protocol than with the short one if they had an FSH/LH ratio < 3.0 (48.5% vs. 25.8%, P = .034), < 2.5 (53.3% vs. 28.6%, P = .030) or < 2.0 (57.8% vs. 21.7%, P = .005). Pregnancy rates were similar with the long and short protocols in patients with FSH/LH > or = 3.0 (57.1% vs. 70%, P = .521), FSH/LH > or = 2.5 (40% vs. 53.8%, P = .435) or FSH/LH > or = 2.0 (40% vs. 55.6%, P = .281). CONCLUSION: This study failed to demonstrate that FSH/LH was a useful parameter for predicting reproductive outcome in IVF programs and for patient selection for the long or short gonadotropin-releasing hormone agonist protocol.

Buserelin↗
PubMed1996

Agenesis of the ductus venosus in a case of monochorionic twins which mimics twin-twin transfusion syndrome.

We describe a pair of monochorionic twins with clinical manifestation of twin-twin transfusion syndrome, including discordant fetal growth, hydrops of the larger twin, and the 'stuck twin' phenomenon of the smaller twin. In the hydropic twin, we found agenesis of the ductus venosus and an abnormal umbilical vein draining directly into the inferior vena cava. There was also marked enlargement of the right atrium, representing the volume overload on it. We believe that the agenesis of the ductus venosus in the larger twin may have contributed to the 'unbalanced shunting' between the monochorionic twins. This then led to a clinical picture mimicking that seen in the authentic twin-twin transfusion syndrome.

Adult↗
PubMed1996

Malignant ovarian germ cell tumors.

OBJECTIVES: Fifty patients with malignant ovarian germ cell tumors, which accounts for 10.8% of all ovarian malignancies, were treated from 1977 through 1994. Their cases are reviewed. METHODS: The histology includes endodermal sinus tumor (EST) in 15 patients, immature teratoma in 14, dysgerminoma in 13, and mixed germ cell tumor in eight. The mean age at presentation was 21.5 years and mean primary tumor diameter was 16 cm. All patients underwent surgery as the initial treatment, and 10 received more than one operation. Postoperative adjuvant chemotherapy was not given to cases with stage Ia immature teratoma and dysgerminoma. VAC (vincristine, actinomycin D, cyclophosphamide) and BVP (bleomycin, vinblastine, cisplatin) regimens were utilized in early 1980s for EST and advanced-stage tumors of immature teratoma and dysgerminoma. BEP (bleomycin, etoposide, cisplatin) and EP (etoposide, cisplatin) regimens were applied in advanced-stage disease and some stage I disease since 1990. VIP (VP-16, ifosfamide, cisplatin) regimen was employed as salvage regimen in cases where other combinations failed. RESULTS: alpha-Fetoprotein (AFP) was elevated in every tumor containing endodermal sinus element, and AFP served as a good indicator for prediction of tumor recurrence. The follow-up time ranged from 5 to 144 months with the mean of 54.5 months. CONCLUSIONS: The survival rate for EST was 54%, that for immature teratoma and dysgerminoma was 85% and 90%, respectively.

Adolescent↗
PubMed1995

Adenoviral-mediated gene transfer into primary human and mouse mammary epithelial cells in vitro and in vivo.

Primary mammary epithelial cells from both the human and mouse mammary glands can be genetically altered under a variety of situations using the replication-defective adenoviral vector containing a marker gene encoding the E. coli beta-galactosidase. Primary human and mouse mammary epithelial cells in monolayer culture and in three-dimensional collagen gel culture systems were transduced by adenovector at high efficiency. Successful gene transfer was also accomplished in situ and in vivo. In the mouse mammary gland, anatomically restricted gene transfer and expression was demonstrated by micro-injection of adenoviral vector directly into the main duct of the mammary gland. Injection of adenoviral vector directly into the human mammary tissues from reduction mammoplasty specimens, into the mouse mammary gland-free fat pad containing the previously transplanted dissociated human mammary epithelial cells, and intratumorally into the human breast cancer xenografts in nude mice, all resulted in successful gene transfer to human mammary epithelial cells. High efficiency introduction of genetic material into primary mammary epithelial cells is important in the study of mammary carcinogenesis and potentially for gene therapy of human breast cancer.

Adenoviridae↗
PubMed1995

Editing of glutamate receptor subunit B pre-mRNA in vitro by site-specific deamination of adenosine.

Editing of the glutamate receptor subunit B (GluR-B) pre-mRNA at a single adenosine residue results in an amino-acid change that profoundly alters the electrophysiological properties of the receptor. Here we show that the GluR-B pre-mRNA is efficiently and accurately edited in vitro, and that base-pair interactions between the editing site and a sequence in the downstream intron are required for substrate recognition. In addition, we directly demonstrate that editing results from the conversion of adenosine to inosine by enzymatic deamination. The biochemical properties of this GluR-B editing activity are similar to those of a double-stranded-RNA-dependent adenosine deaminase, but RNA competition and column fractionation experiments indicate that the GluR-B editing and deaminase activities are distinct. Thus, the GluR-B editing enzyme may contain the adenosine deaminase, or a similar activity, and an RNA recognition subunit that specifically targets the enzyme to the editing site.

Adenosine↗
PubMed1995

Photoageing-associated mitochondrial DNA length mutations in human skin.

It has recently been suggested that mitochondrial DNA (mtDNA) mutations are important contributors to human ageing and degenerative diseases. Using PCR techniques, we demonstrated three types of mtDNA length mutations, a 4977 bp deletion, a 7436 bp deletion and tandem duplications, in normal human skin tissues. We found that these mutations started to appear in the third decade of life, and the age at which the mutations could be detected in sun-exposed skin was usually younger than in non-exposed skin. Moreover, the incidences of these deletions and tandem duplications of mtDNA in sun-exposed skin were all significantly higher than those in non-exposed skin (P < 0.05). The 4977 bp deletion was the most prevalant mtDNA mutation in human skin, and the 7436 bp deletion was the least frequent among the three types of mtDNA mutations examined. We first demonstrated the existence of tandem duplications with sizes of about 260 bp, 200 bp and 150 bp in the D-loop region of mtDNA in the skin of elderly individuals. Among the three tandem duplications, the 200-bp duplication was found to occur most frequently in ageing skin. The tandem duplications were found to coexist with either or both of the deletions in some elderly individuals. The frequency of occurrence of mtDNA deletions and tandem duplications in skin was found to increase in an age-dependent manner. However, the incidence of tandem duplications was not well correlated with the age of the subject.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Chronic exercise enhances endothelium-mediated dilation in spontaneously hypertensive rats.

This study investigated the effect of physical training on endothelial function in spontaneously hypertensive rats (SHR). After 3 months, in conscious trained- and untrained-SHR body weight, systolic blood pressure and heart rate were 220 +/- 6 g vs 271 +/- 9 g, 172 +/- 7 mmHg vs 210 +/- 8 mmHg and 314 +/- 10 vs. 348 +/- 12 beats/min, respectively. In vitro, the dose-response curves of norepinephrine in isolated intact aortic and mesenteric rings form the exercise trained-SHR were significantly lower than those from the untrained-SHR. With denuded preparations, norepinephrine concentration-response curves were shifted to the left both in the trained- and untrained-SHR. This shift in the trained-SHR exceeded that in the untrained-SHR. The vasodilator response to acetylcholine in the trained-SHR was significantly greater than that in the untrained-SHR. Either N omega-nitro-L-arginine (100 mumol/l) or methylene blue (10 mumol/l) inhibited acetylcholine-induced vasodilator effect in aorta of trained- and untrained-SHR, but not in mesenteric artery of trained-SHR. Tetraethylammonium (10 mmol/l) inhibited significantly the N omega-nitro-L-arginine and methylene blue-resistant relaxation in mesenteric artery of trained-SHR, but not only by indomethacin (10 mumol/l). Collectively, these data demonstrate that chronic exercise increases EDRF/EDHF production (presumably by increasing endothelial shear stress), and may contribute to the enhanced effects of post-exercise hypotension.

Acetylcholine↗
PubMed1995

Destructive encephalopathy in incontinentia pigmenti: a case report.

We report a 2-day-old neonate with incontinentia pigmenti combined with destructive encephalopathy. Generalized seizures developed soon after birth; characteristic papulovesicles and hyperpigmented linear streaks appeared several days later. The brain CT scan showed multiple low density areas with cortical atrophy and ventricular enlargement. Histopathological examination favored the diagnosis of incontinentia pigmenti. Although a series of microbiological examinations failed to identify any infectious agent, the patient was still treated vigorously with anticonvulsants, systemic antibiotics, and acyclovir from the beginning of hospitalization. However, the seizures persisted, and the patient died 26 days after birth. Our report suggests that incontinentia pigmenti with encephalopathy may have a fatal prognosis.

Anticonvulsants↗