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Biomedical subjects

Y W Li

Publications and source records attributed to Y W Li.

At least 91 records · Page 5Linked to original sources
PubMed1995

C1 neurons of neonatal rats: intrinsic beating properties and alpha 2-adrenergic receptors.

Tyrosine-hydroxylase-immunoreactive (TH-ir) neurons (C1 cells) of the rostral ventrolateral medulla (RVL) control sympathetic tone and may be inhibited by the hypotensive drug clonidine. The present study seeks to describe some of the intrinsic properties of bulbospinal C1 cells and to establish whether they have alpha 2-adrenergic inhibitory "autoreceptors." RVL bulbospinal cells (retrogradely labeled with microbeads) were recorded in thin slices from 3- to 7-day-old rats with patch electrodes containing Lucifer yellow. Forty-two of eighty-nine cells were recovered histologically, and 69% were TH-ir. The properties of TH-ir cells could not be distinguished from those of the other bulbospinal cells. Most cells were spontaneously active (0.5-5 spikes/s). Blockade of fast postsynaptic potentials with kynurenic acid plus bicuculline plus strychnine or with a low-Ca(2+)-high-Mg2+ medium failed to reduce their firing rate. The membrane trajectory consisted of one of two patterns interconvertible by injections of depolarizing or hyperpolarizing current: 1) depolarizing ramps leading to spikes or 2) slow oscillations (tetrodotoxin resistant but absent at hyperpolarized potentials) leading to spikes or repolarization. The cells had Ca(2+)-dependent afterhyperpolarizations, large transient outward currents, and a hyperpolarization-activated inward current activated at potentials less than -65 mV, blocked by CsCl, and presumably responsible for a large inward rectification. Of 27 TH-ir cells, 21 had inhibitory responses to alpha 2-adrenergic agonists. These were blocked by idazoxan (n = 9). alpha 2-Agonists activated an inwardly rectifying potassium conductance (KIR). We confirm that bulbospinal C1 cells have intrinsic pacemaker properties and demonstrate that they have alpha 2-adrenergic receptors (autoreceptors) coupled to KIR channels.

Adrenergic alpha-Agonists↗
PubMed1995

Crossed, unfused ectopic kidney with a single ectopic ureter: report of a case.

A 10-year-old girl with an ectopic kidney and a single ectopic ureter inserted into the vaginal vestibule is reported. Abdominal sonography showed a hypoplastic left kidney located in the right lower abdomen. The associated ureter was dilated and tortuous, and did not open into the bladder. Diagnosis was confirmed by retrograde urogram via the ectopic ureteral orifice on the vestibule.

Child↗
PubMed1995

Unilateral occlusion of duplicated uterus with ipsilateral renal anomaly in young girls: a study with MRI.

Twenty-four young girls (mean age 13.0 years) with unilateral occlusion of a duplicated uterus and ipsilateral renal agenesis, dysplasia or hypoplasia were studied with magnetic resonance imaging (MRI) following ultrasound examination. Hydrocolpos (n = 4), hydrometrocolpos (n = 2), hematocolpos (n = 11), hematometrocolpos (n = 5), hematocolpometra, hematosalpinx (n = 3) and hematometra, hematosalpinx (n = 1) were noted (two of these patients had presented with hydrocolpos and hematocolpos before and after the menarche). Twenty-two of these girls presented with ipsilateral renal agenesis (right 11, left 11) with ectopic ureters to Gartner's duct cysts (GDC) in two, in one renal hypoplasia and in one renal dysplasia with ectopic ureters to GDC. MRI offered specific images of the genital tract, showing the exact type of müllerian duct anomaly and providing high diagnostic accuracy. Such preoperative identification of a uterine anomaly, complemented with appropriate surgical intervention, can assist young girls in achieving normal fertility in the future.

Abnormalities, Multiple↗
PubMed1994

Usefulness of magnetic resonance imaging in the assessment of venoatrial connections, atrial morphology, bronchial situs, and other anomalies in right atrial isomerism.

Multiple complex venous and intracardiac anomalies are frequently seen in patients with right atrial isomerism, and complete anatomic information may not always be obtained from combined echocardiography and angiography. Twenty patients with right atrial isomerism were prospectively studied with use of magnetic resonance imaging (MRI); satisfactory imaging was obtained in 18 patients, aged 6 days to 12 years (median 3 months). All patients had undergone echocardiography, cardiac catheterization, and angiocardiography. The purpose of this study was to assess the usefulness of MRI in the evaluation of venoatrial connections, atrial morphology, bronchial situs, and additional anomalies. Bilateral superior venae cavae were documented in 12 patients and anomalous hepatic venous drainage in 11. The pulmonary venous system was imaged in all 18 patients, of whom 12 had total anomalous pulmonary venous connection: 9 supracardiac, 2 infracardiac, and 1 mixed type. Some obstruction to pulmonary venous return was present in 9 of the 12 patients, and the site of obstruction was demonstrated by MRI in 6. Bilateral morphologic right atrial appendages were imaged in 7 patients. Bilateral morphologic right bronchi were identified in 17 patients, asplenia was confirmed in 17 of 18 patients by the absence of splenic tissue on imaging, and hiatal hernia was imaged in 4. Compared with angiography and echocardiography, MRI more clearly defined the pulmonary venous connections in 10 patients with pulmonary venous obstruction. Anomalous hepatic venous connections were better defined by MRI in 2. Therefore, MRI provided valuable supplementary information on the cardiovascular and visceral anomalies in these patients.

Abnormalities, Multiple↗
PubMed1994

Gastrointestinal bleeding and paraparesis in blue rubber bleb nevus syndrome.

Blue rubber bleb nevus syndrome (BRBNS), which consists of cutaneous and visceral hemangiomas, is a rare disease. Complications such as gastrointestinal (GI) bleeding, anemia and coagulopathy have been documented. We report a patient with BRBNS who presented with acute paraparesis in addition to GI bleeding and coagulopathy.

Blood Coagulation Disorders↗
PubMed1994

Expression of Fos-like protein in brain following sustained hypertension and hypotension in conscious rabbits.

The purpose of this study was to examine comprehensively and quantitatively the effects of sustained hypertension and hypotension on neuronal expression of Fos, the protein product of the proto-oncogene c-fos, in the brain of conscious rabbits. Hypertension or hypotension was produced by continuous intravenous infusion of phenylephrine or nitroprusside, at a rate sufficient to increase or decrease, respectively, arterial pressure by 20-30 mmHg, maintained for a period of 60 min. In comparison with a sham control group of rabbits that were infused with the vehicle solution alone, hypertension induced a significant increase in Fos immunoreactivity in the area postrema, the nucleus tractus solitarii, the caudal and intermediate ventrolateral medulla, the lateral parabrachial nucleus and the central nucleus of the amygdala. Double-labelling for tyrosine hydroxylase and Fos immunoreactivity showed that few (approximately 5%) of the Fos-positive neurons in the caudal and intermediate ventrolateral medulla in this group of animals were also positive for tyrosine hydroxylase. Hypotension also produced a significant increase in Fos immunoreactivity in the above regions, as well as in the rostral ventrolateral medulla, the A5 area, the locus coeruleus and subcoeruleus, the paraventricular nucleus, the supraoptic nucleus, the arcuate nucleus and the medial preoptic area. Approximately 65% of neurons in the rostral, intermediate and caudal ventrolateral medulla that expressed Fos following hypotension were also positive for tyrosine hydroxylase. Similarly, in the pons, approximately 75% of Fos-positive cells in the locus coeruleus, subcoeruleus and A5 area were positive for tyrosine hydroxylase. In the hypothalamus, 92% of Fos-positive neurons in the supraoptic nucleus, and 37% of Fos-positive neurons in the paraventricular nucleus, were immunoreactive for vasopressin. Our results demonstrate that hypertension and hypotension induce reproducible and specific patterns of Fos expression in the brainstem and forebrain. The distribution patterns and chemical characteristics of Fos-positive neurons following sustained hypertension or hypotension are significantly different. In particular, hypotension, but not hypertension, caused Fos expression in many tyrosine hydroxylase-positive cells within all pontomedullary catecholamine cell groups.

Animals↗
PubMed1994

Early detection of unilateral occlusion of duplicated müllerian ducts: the use of serial pelvic sonography for girls with renal agenesis.

For early detection of unilateral occlusion of duplicated müllerian ducts, serial pelvic sonography was performed in 215 girls with known renal agenesis, especially following menarche, during the last 6 years. To date, 16 girls with unilateral occlusion of duplicated müllerian ducts were detected. We stress the value of this modality, which can lead to a prompt diagnosis, and allow for early and appropriate surgical intervention.

Abnormalities, Multiple↗
PubMed1994

Analysis of p53 gene mutations in human gliomas by polymerase chain reaction-based single-strand conformation polymorphism and DNA sequencing.

Mutations in the p53 gene have been recognized in brain tumors, and clonal expansion of p53 mutant cells has been shown to be associated with glioma progression. However, studies on the p53 gene have been limited by the need for frozen tissues. We have developed a method utilizing polymerase chain reaction (PCR) for the direct analysis of p53 mutation by single-strand conformation polymorphism (SSCP) and by direct DNA sequencing of the p53 gene using a single 10-microns paraffin-embedded tissue section. We applied this method to screen for p53 gene mutations in exons 5-8 in human gliomas utilizing paraffin-embedded tissues. Twenty paraffin blocks containing tumor were selected from surgical specimens from 17 different adult patients. Tumors included six anaplastic astrocytomas (AAs), nine glioblastomas (GBs), and two mixed malignant gliomas (MMGs). The tissue section on the stained glass slide was used to guide microdissection of an unstained adjacent tissue section to ensure > 90% of the tumor cell population for p53 mutational analysis. Simultaneously, microdissection of the tissue was also carried out to obtain normal tissue from adjacent areas as a control. Mutations in the p53 gene were identified in 3 of 17 (18%) patients by PCR-SSCP analysis and subsequently confirmed by PCR-based DNA sequencing. Mutations in exon 5 resulting in amino acid substitution were found in one thalamic AA (codon 158, CGC > CTT: Arg > Leu) and one cerebral hemispheric GB (codon 151, CCG > CTG: Pro > Leu).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Infantile endodermal sinus tumor presenting with vaginal bleeding: report of a case.

Endodermal sinus tumor (EST) of the vagina is extremely rare and primarily affects infants. We report on a six-month-old female infant with EST of the vagina who presented with vaginal spotting of one month's duration. Pelvic ultrasound and computerized tomography showed a 3.8 x 3.5 cm heterogeneous mass between the bladder and the rectum. The serum alpha-fetoprotein (AFP) level was high (1270 ng/mL) and the beta-human chorionic gonadotropin was undetectable. She received surgical intervention followed by chemotherapy. The patient was disease-free and serum AFP remained undetectable during the eight-month follow-up period.

Endodermal Sinus Tumor↗
PubMed1994

Electrochemical therapy (ECT) for thyroid adenoma during acupuncture anaesthesia: analysis of 46 patients.

Between February 1989 and April 1993, 46 patients with thyroid adenoma were treated by electrochemical treatment (ECT) during acupuncture anaesthesia. After three months to four years follow up period, the cure rate was 97.8%. ECT is a new technique which provides simple, effective and safe treatment of thyroid adenoma. Treatment of benign tumours with ECT represents a new application.

Acupuncture Analgesia↗
PubMed1994

[The analysis of plain film presentation and bone age of achondroplasia].

Achondroplasia is the most common type of inheritant dwarfism. The diagnosis is mainly depended on clinical and plain film presentation. This study mainly focus on the characteristic presentation of plain film in achomdroplasia. We try to find the most consistent presentation and explain it through the development and growth of bone. The presentation in our 16 cases is as follows: Metaphyseal flaring 100% (16/16), Concave backs of vertebral body 100% (4/4), Short & wide tubular bone of hand & foot 85% (12/24). Square iliac bone 78% (11/14), Flare anterior end of ribs 76% (10/13), Decrease interpeduncular distance of lower L-spines 64% (9/14), Proimal < distal tubular bone 33% (5/15). Disproportionately long fibular bone 8% (1/13). We also analyze the heritant characteristics and conclude that most of achondroplasia are caused by mutation. The heritant trait is only 6%. According to bone age study, we found high percentage (31%) of delayed bone maturation.

Achondroplasia↗
PubMed1994

Findings of anomalous pulmonary venous return using MRI.

This study represents a preliminary retrospective assessment of the value of spin-echo magnetic resonance imaging (MRI) in detecting and describing total or partial anomalous pulmonary venous return (APVR). MRI was performed in 21 cases of APVR; orthogonal planes were used in all. Of the 21 cases, 19 were classified as total APVR (TAPVR) and two were partial APVR (PAPVR). Of the 19 cases of TAPVR, seven supracardiac, nine cardiac, one infracardiac and two mixed type were noted. The detection rate of each pulmonary vein combined in all three planes was 57% in the right superior pulmonary vein (RSPV), 62% in the left superior pulmonary vein (LSPV), 76% in the right inferior pulmonary vein (RIPV), and 86% in the left inferior pulmonary vein (LIPV). The axial plane was most effective (RSPV: 38%; LSPV: 52%; RIPV: 71%; LIPV: 81%). The coronal plane offered a better detection rate than the axial plane in RSPV (43%) and additional information of bronchial and visceral situs. Imaging of the combined axial and coronal planes was sufficient to evaluate each individual pulmonary vein. The sagittal plane gave no additional information in this respect. Accurate identification of pulmonary venous confluence and anomalous pulmonary venous channel was 95% (20/21). Limitation of echocardiography and and angiocardiography makes cardiac MRI important in assessing pulmonary vein and pulmonary venous confluence. It obviates the need for invasive angiocardiography and is an important supplement to an inadequate echo.

Adolescent↗
PubMed1994

Persistent hyperinsulinemic hypoglycemia due to nesidiodysplasia in a neonate.

A large, one-hour-old female baby was noted to have hypoglycemia immediately after birth. Although early feeding and then intravenous glucose infusion with a dose gradually increased to 30 mg/kg/min were given, the baby still had recurrent hypoglycemia 14 days after birth. High serum insulin/glucose ratios (> 2.5) were noted twice during hypoglycemic episodes. At the same time, the baby's serum growth hormone, thyroid hormone and cortisol levels were within normal ranges. Hyperinsulinism due to nesidiodysplasia was diagnosed and a near-total pancreatectomy was performed at the age of 14 days. After the operation, euglycemia was achieved and there was no episode of hypoglycemia even after fasting for eight hours. Our experience confirms that surgery is the treatment of choice for patients, including neonates, with hyperinsulinemic hypoglycemia.

Female↗
PubMed1994

Sexual precocity due to intracranial human chorionic gonadotropin-secreting tumor: report of a case.

Human chorionic gonadotropin (HCG)-secreting tumors are one of the causes of isosexual precocity in boys. A seven-year-old boy had been noted to have an increased appetite, accelerated growth and the development of pubic hair in the previous three months. He had an elevated serum testosterone level (16.79 ng/mL). However, the response of luteinizing-hormone and follicle-stimulating-hormone to gonadotropin releasing hormone stimulation was suppressed. An intracranial tumor at the left thalamus was disclosed by a magnetic resonance image scan of the head, and an elevated HCG level (120 mIU/mL) was also noted. Sexual precocity due to an intracranial HCG-secreting tumor was diagnosed and a partial resection of the tumor followed by radiotherapy was carried out. His serum testosterone and HCG levels became undetectable, and the secondary sexual characteristics regressed after treatment.

Brain Neoplasms↗
PubMed1993

Comparison of the pressor effects of angiotensin II and III in the rostral ventrolateral medulla.

Microinjection of angiotensin II and III into the rostral ventrolateral medulla of anesthetized barodenervated rabbits elicited in both cases pressor responses, which were of similar magnitude and time course. The responses to angiotensin II and III were either unchanged or increased in the presence of compounds which inhibit their degradation to shorter length peptides. The results indicate that both angiotensin peptides are independently capable of eliciting pressor responses in the rostral ventrolateral medulla.

Angiotensin II↗
PubMed1993

Detection of human papillomavirus (HPV) DNA in human prostatic tissues by polymerase chain reaction (PCR).

Human papillomavirus (HPV) infections are strongly linked to the pathogenesis of uterine cervical neoplasms, and have been implicated in other cancers of the female genital tract. In contrast, the association of HPV with the cancers of the male urogenital tract is less evident, except in anal and penile cancers. However, recent studies reporting the prevalence of HPV infections in human prostate cancers (60-100% HPV 16 positive vs. no infection of HPV) have raised controversies regarding the prevalence of HPV in benign and neoplastic human prostate. We investigated the prevalence of HPV infections in prostatic intraepithelial neoplasia (PIN) and prostatic adenocarcinomas in 23 surgically resected prostates. Polymerase chain reaction (PCR) was used to amplify HPV 6b/11, 16, and 18 specific DNA sequences, using type specific HPV primers selected from the transforming gene E6-E7. The areas of PIN and cancer in 6 microns H&E stained tissue sections were identified, and respective areas of PIN and cancer were isolated from the adjacent serial sections and used for DNA amplification and HPV detection (Fig. 1). Our results demonstrated the presence of HPV 16 in three carcinomas (13%), using type specific primers in PCR amplified samples. We were not able to demonstrate the presence of other HPV types (HPV 6b/11 or HPV 18) in any of the samples using specific primers. Two of these prostates showed relatively strong positive signals by dot blot analysis, when hybridized with a 32P-labeled HPV 16 type specific oligonucleotide probe. One more sample showed weak positivity, when hybridized with a 32P-labeled HPV 16 type specific oligonucleotide probe. Subsequently, we have confirmed these results by Southern hybridization of the samples transferred to nylon membrane after agarose gel electrophoresis and detected by HPV 16 type specific oligonucleotide probe, using chemiluminescent assay. We, therefore, conclude that HPV infections of the prostate in general are not as common as has been previously claimed by other investigators.

Adenocarcinoma↗
PubMed1993

Association of hiatus hernia with asplenia syndrome.

During a 13-month period, 13 patients with asplenia syndrome were evaluated with MRI for cardiovascular and visceral anomalies. The MR images were reviewed for the presence of haitus hernia which was found in three patients. One of the remaining ten patients with no MRI evidence of hiatus hernia was diagnosed as having gastro-oesophageal reflux and hiatus hernia by an oesophagogram and 24-h pH monitoring. This patient had undergone fundoplication prior to MRI. Out of the 13 patients (31%) with asplenia syndrome, 4 had hiatus hernia. It appears that among patients with the asplenia syndrome, hiatus hernia is a frequent finding. Recurrent pneumonia or bronchiolitis in patients with asplenia syndrome requires evaluation for the presence of hiatus hernia and gastro-oesophageal reflux.

Adolescent↗