Biomedical subjects

J Huang

Publications and source records attributed to J Huang.

At least 469 records · Page 26Linked to original sources

PubMed1998

Unsuspected pulmonary embolism: prospective detection on routine helical CT scans.

PURPOSE: To determine the prevalence of unsuspected pulmonary embolism (PE) on routine thoracic helical computed tomographic (CT) scans and to quantify the improvement in PE detection by using a cine-paging mode on a workstation instead of hard-copy review. MATERIALS AND METHODS: Seven hundred eighty-five patients referred for routine contrast medium-enhanced thoracic CT within 9 months were prospectively recruited. Helical CT was performed. Studies were prospectively interpreted by four radiologists. Two radiologists performed routine, undirected, hard-copy consensus review for official interpretation; two of three thoracic radiologists independently performed a dedicated workstation-based search for PE. The presence of PE involving the main, lobar, or segmental pulmonary arteries was assigned a score of 1-5 (1 = definitely negative, 5 = definitely positive) by each independent reviewer. Patients with a score of 4 or 5 underwent lower-extremity ultrasound, ventilation-perfusion scintigraphy, or both, followed by pulmonary CT angiography if the findings were still equivocal. RESULTS: Twelve (1.5%) of the 785 patients had unsuspected PE, with an inpatient prevalence of 5% (eight of 160) and an outpatient prevalence of 0.6% (four of 625). Of the 12 patients with unsuspected PE, 10 (83%) had cancer. Of the 81 inpatients with cancer, seven (9%) had unsuspected PE. A dedicated workstation-based search resulted in detection of PE in three more patients (25%) than did hard-copy interpretation. CONCLUSION: The prevalence of unsuspected PE was highest among inpatients with cancer. A directed, workstation-based search can improve the PE detection rate over that with hard-copy review.

Adolescent↗

PubMed1998

Effect of hypoxia on pulmonary blood flow-segmental vascular resistance relationship in perfused cat lungs.

To investigate the effect of alveolar hypoxia on the pulmonary blood flow-segmental vascular resistance relationship, we determined the longitudinal distribution of vascular resistance while increasing blood flow during hyperoxia or hypoxia in perfused cat lungs. We measured microvascular pressures by the micropipette servo-null method, partitioned the pulmonary vessels into three segments [i.e., arterial (from main pulmonary artery to 30- to 50-micron arterioles), venous (from 30- to 50-micron venules to left atrium), and microvascular (between arterioles and venules) segments] and calculated segmental vascular resistance. During hyperoxia, total resistance decreased with increased blood flow because of a reduction of microvascular resistance. In contrast, during hypoxia, not only microvascular resistance but also arterial resistance decreased with increase of blood flow while venous resistance remained unchanged. The reduction of arterial resistance was presumably caused by arterial distension induced by an elevated arterial pressure during hypoxia. We conclude that, during hypoxia, both microvessels and arteries >50 micron in diameter play a role in preventing further increases in total pulmonary vascular resistance with increased blood flow.

Animals↗

PubMed1998

Depressed ventilatory response to hypoxia in hypothermic newborn piglets: role of glutamate.

To evaluate whether changes in extracellular glutamate (Glu) levels in the central nervous system could explain the depressed hypoxic ventilatory response in hypothermic neonates, 12 anesthetized, paralyzed, and mechanically ventilated piglets <7 days old were studied. The Glu levels in the nucleus tractus solitarius obtained by microdialysis, minute phrenic output (MPO), O2 consumption, arterial blood pressure, heart rate, and arterial blood gases were measured in room air and during 15 min of isocapnic hypoxia (inspired O2 fraction = 0.10) at brain temperatures of 39.0 +/- 0.5 degrees C [normothermia (NT)] and 35.0 +/- 0.5 degrees C [hypothermia (HT)]. During NT, MPO increased significantly during hypoxia and remained above baseline. However, during HT, there was a marked decrease in MPO during hypoxia (NT vs. HT, P < 0.03). Glu levels increased significantly in hypoxia during NT; however, this increase was eliminated during HT (P < 0.02). A significant linear correlation was observed between the changes in MPO and Glu levels during hypoxia (r = 0.61, P < 0.0001). Changes in pH, arterial PO2, O2 consumption, arterial blood pressure, and heart rate during hypoxia were not different between the NT and HT groups. These results suggest that the depressed ventilatory response to hypoxia observed during HT is centrally mediated and in part related to a decrease in Glu concentration in the nucleus tractus solitarius.

Acid-Base Equilibrium↗

PubMed1998

Effect of L-aspartate on the ventilatory response to hypoxia in sedated newborn piglets.

L-aspartate (L-ASP) acts as an excitatory amino acid neurotransmitter at the synapses of brain stem respiratory neurons. In order to determine the effect of L-ASP on the neonatal ventilatory response to hypoxia, 9 control piglets [age 4.3 +/- (SD) 0.9 days, weight 1.9 +/- 0.5 kg] and 9 L-ASP-treated animals [age 5.0 +/- (SD) 1.4 days, weight 2.1 +/- 0.7 kg] were studied. Minute ventilation, oxygen consumption, arterial blood pressure, and blood gases were measured in sedated piglets while spontaneously breathing room air and during 1, 5, and 10 min of hypoxia (O2 concentration in inspired gas 0.10). Measurements were obtained before and 60 min after the administration of L-ASP (580 mg/kg i.v. over 1 h) or 5% dextrose solution. In the control animals, the ventilatory response to hypoxia was similar before and after dextrose infusion. In contrast, a significant and sustained increase in ventilation was observed at 1, 5, and 10 min of hypoxia after the administration of L-ASP. Changes in oxygen consumption, heart rate, arterial blood pressure, pH, and arterial O2 tension with hypoxia were similar before and after the L-ASP infusion, while the arterial CO2 tension decreased significantly during hypoxia after the administration of L-ASP. These data suggest that the excitatory amino acid L-ASP is an important mediator of the hypoxic hyperventilation in the neonate. We speculate that the administration of exogenous L-ASP modifies the balance of central nervous system neurotransmitters during hypoxia, resulting in predominance of excitatory neurotransmission.

Anesthesia↗

PubMed1998

Pharyngeal cross-sectional area and pharyngeal compliance in normal males and females.

Obstructive sleep apnea syndrome is ascribed to pharyngeal dysfunction, but there are only a few reports about the normal morphological values in this anatomical region. We measured the pharyngeal cross-sectional area and the compliance (collapsibility), using the acoustic reflection technique with air breathing, in 181 healthy subjects (age 21-69 years). We assessed their sex-related differences, and the effects of age, body size and body postures on these parameters. The pharyngeal cross-sectional area, defined as the region from the fauces to the glottis, posturally changed with successive decreases in the sitting, left lateral decubitus and supine positions. The area was significantly greater in male than in female subjects in the sitting position (p < 0.01), but no difference was present in the recumbent positions. The pharyngeal cross-sectional area did not correlate with either age or body size. The specific pharyngeal compliance was greater in the males than in the females (p < 0.01) and increased with age only in the male subjects.

Adult↗

PubMed1998

In vivo efficacy of SM-20302, a GP IIb/IIIa receptor antagonist, correlates with ex vivo platelet inhibition in heparinized blood but not in citrated blood.

We tested the hypothesis that the in vivo antithrombotic efficacy of SM-20302, a GP IIb/IIIa receptor antagonist, correlates with the ex vivo platelet inhibition in heparinized platelet rich plasma (hPRP) but not in citrated PRP (cPRP). The studies were performed in a canine model of carotid artery thrombosis in which thrombus formation was induced by electrolytic injury. Thrombosis of the right carotid artery was induced immediately after the administration of saline (n=12). Thirty minutes after persistent occlusive thrombosis was obtained, the vessel segment was ligated, and the time to occlusion and thrombus weight were noted. Subsequently, thrombosis of the left carotid artery was initiated in the presence of SM-20302 (100, 300, 600, or 1000 microg/kg i.v.; n=4 to 6). All the doses of SM-20302 inhibited (by > or = 90%) the ex vivo platelet aggregation induced by ADP and arachidonic acid (AA) in cPRP. In hPRP, a dose-dependent inhibition of ex vivo platelet aggregation was observed. The maximal inhibition produced by 100 to 1000 microg/kg SM-20302 ranged from 18% to 80% for ADP and 44% to 88% for AA. Maximal prolongation of the template bleeding time induced by the 100-, 300-, 600-, and 1000-microg/kg doses were 2.5-, 9.5-, 10-, and > 10-fold, respectively. All the injured carotid arteries (n=12) in the saline-treated group occluded. SM-20302 pretreatment produced a dose-dependent maintenance of the carotid artery patency, and the incidence of occlusion at 4 hours was 5/6, 3/6, 0/6, and 0/6 for the 100-, 300-, 600-, and 1000-microg/kg doses, respectively. The results indicate that SM-20302 prevents carotid artery thrombosis in response to electrolytic arterial wall injury and that its in vivo antithrombotic efficacy can be correlated accurately with the ex vivo platelet inhibition in PRP prepared from heparinized blood but not from citrated blood.

Animals↗

PubMed1998

Intermediate myasthenia syndrome following acute organophosphates poisoning--an analysis of 21 cases.

1. Twenty-one cases out of 272 patients of acute organophosphates poisoning were diagnosed as intermediate syndrome (IMS) with a prevalence at 7.7%. The responsible OP insecticides included parathion, omethoate and some OP containing pesticide mixtures. IMS occurred mainly in severe OP poisoning patients who recovered from the acute cholinergic crisis at 7-75 h after the onset of acute poisoning. 2. Muscular weakness appeared in the following three categories of muscles: (1) neck flexors and proximal limb muscles; (2) muscles innervated by motor cranial nerves and/or (3) respiratory muscles. Blood acetylcholinesterase activity was persistently inhibited. Electroneuromyography (ENMG) with repetitive nerve stimulation (RNS) at frequencies of 20 Hz or 30 Hz in seven patients showed decrements of common muscle action potentials during the presence of myasthenia in five patients and became normal when their muscle strength recovered. 3. Mild IMS recovered within 2-7 days and had a favorable prognosis. Severe IMS patients with respiratory paralysis needed immediate endotracheal intubation and mechanical ventilation. Recovery of weakness of the respiratory muscles and proximal limb muscles took longer, the slowest being 30 days. Four of the patients died of respiratory paralysis and the fatality rate was 19%. 4. The mechanism of IMS remains to be further investigated. The RNS/ENMG changes indicate a post-synaptic block at the neuromuscular junctions. 5. In order to promote the recognition of this syndrome, we proposed to name the syndrome as Intermediate Myasthenia Syndrome (IMS).

Adolescent↗

PubMed1998

Prognostic factors in the treatment of human immunodeficiency virus-associated non-Hodgkin's lymphoma: analysis of AIDS Clinical Trials Group protocol 142--low-dose versus standard-dose m-BACOD plus granulocyte-macrophage colony-stimulating factor. National Institute of Allergy and Infectious Diseases.

PURPOSE: The overall results of chemotherapy in human immunodeficiency virus (HIV)-associated non-Hodgkin's lymphoma (NHL) have been poor. To define a subgroup of patients who may have a better outcome, an analysis of prognostic factors was performed of patients treated in AIDS Clinical Trials Group (ACTG) protocol 142, a phase III randomized trial of low-dose versus standard-dose methotrexate, bleomycin, doxorubicin, cyclophosphamide, vincristine, and dexamethasone (m-BACOD) plus granulocyte-macrophage colony-stimulating factor (GM-CSF) for the treatment of patients with newly diagnosed HIV-associated NHL. MATERIALS AND METHODS: The following baseline variables were included as potential predictors of survival among 192 patients who received treatment: age; intravenous drug use (IVDU); specific type of sexual contact as risk factors (homosexual, bisexual, or heterosexual contact); prior AIDS diagnosis; CD4 cell count; serum lactic acid dehydrogenase (LDH); histology; Karnofsky performance status (KPS); stage; B symptoms; race (white/nonwhite); nodal involvement; extranodal involvement; number of extranodal sites; specific sites: bone marrow, liver, kidney, lung, or gastrointestinal tract; and treatment arm (standard-dose m-BACOD/low-dose m-BACOD). RESULTS: Age greater than 35 years, IVDU, stages III/IV, and CD4 cell counts less than 100/microL were adverse prognostic factors in multivariate analyses using the Cox proportional hazards model. The median overall survival for patients with none or one of the adverse factors was 46 weeks, with two was 44 weeks, and with three or four was 18 weeks. At 144 weeks, 29.5% of patients with none or one, 16.9% with two, and 0% with three or four factors were alive (P < .001). CONCLUSION: Long-term survival can be achieved in approximately one third of patients with HIV-associated NHL with favorable characteristics.

Adolescent↗

PubMed1998

Nutritional habits and serum lipid levels in a low-fat intake Chinese population sample.

The dietary intake of macronutrients and of specific minerals and vitamins was measured in a low-fat intake adult population living in a rural area in northwestern China. The total intake of fat amounted to +/- 12% of total energy. The P/S ratio was 2.5 and the U/S ratio 3.8. Carbohydrates provide about 75% of total energy. The mean total serum cholesterol was 148 mg/dl in men and 163 mg/dl in women. The mean HDL-cholesterol level was 38.6 mg/dl in men and 39.4 mg/dl in women, confirming the absence of a significant sex difference in HDL-cholesterol in low-fat consuming populations. Triglyceride levels were similar to those of Western populations. For both sexes taken together a positive correlation was found between the serum cholesterol level and saturated fat intake (p < 0.001) and a negative correlation with the P/S ratio (p < 0.05). Calcium intake was low: 346 mg/d in men and 245 mg/d in women.

Adult↗

PubMed1998

Acute effects of carbofuran in workers of two pesticide plants.

This paper investigates the acute effects of carbofuran in workers of two pesticide-formulating plants. Mean airborne carbofuran concentrations ranged from 0.025 to 1.115 mg/m3 in plant A and from 0.018 to 0.067 mg/m3 in plant B, respectively. In workers of plant A the post-shift blood cholinesterase activity was significantly reduced, compared to pre-shift values. No difference in blood cholinesterase activity was found between pre- and post-shift values in workers of plant B. During the investigation, 25 cases of acute carbofuran poisoning were diagnosed by their clinical picture and depressed cholinesterase activity in blood. Usual symptoms included dizziness, weakness, blurred vision, nausea and sweating. Pallor, epigastric pain, vomiting and chest tightness occurred only in a few cases. Myosis was recorded in 24 cases. Fasciculation of muscle gastrocnemius induced by percussion was found in 6 cases, and four of them had also fasciculation of muscle orbicularis oculi. Inhibition of cholinesterase activity in the blood was related with the clinical features; however, the inhibition was rapidly reversible. In most cases, recovery was complete within 2-3 hours, with or without atropine treatment, after the subjects were removed from exposure. Rapid onset, mild illness and quick recovery are typical characteristics of occupational acute carbofuran poisoning.

Acute Disease↗

PubMed1998

[Relationship between expression of tumor suppressor protein p21 and p53 and cell proliferation in the gastric carcinoma].

To study the relationship between the expressions of tumor supressor protein p21 and p53 and malignant growth of gastric carcinoma, 88 paraffin embedded specimens of gastric carcinoma and gastric ulcer were examined with immunohistochemical method. We found that the expression rate of mutated protein p53 in the gastric carcinoma was about 40% and the expression rate of p21 protein in gastric mucous carcinoma, undifferentiated carcinoma, poorly differentiated carcinoma was obviously low. The expression of PCNA in gastric adenoid cancer was very high. The results suggest that the low expression of p21 proteins and mutation of p53 proteins in gastric cancer cells play a certain role in the morbidity of gastric carcinoma, but its involvement in the malignant growth of gastric carcinoma cells is not obvious.

Adenocarcinoma↗

PubMed1998

[Study on electroneuromyography of 175 workers exposed to carbon disulfide].

A study on electroneuromyography of 175 workers exposed to carbon disulfide demonstrated that electroneuromyographic abnormalities of these workers were in accordance with characteristic alteration of axonal polyneuropathy. Electroneuromyography was an objective and sensitive method to detect the early damage of peripheral nerve caused by low-level exposure to carbon disulfide. The dose-response relationship between the exposure to carbon disulfide and the damage of peripheral nerve was demonstrated.

Adult↗

PubMed1998

[Mechanism for the formation of F-V curve configuration analysed with tangent time constant and wave-speed theory in normal adolescents].

To understand the distribution of F-V curve configuration and the characteristics of tangent time constant (tau t), and to explore the mechanical mechanism for the formation of F-V curve configuration, we measured the tau t of high, mid, low lung volumes (tau t75, tau t50, tau t25) from F-V curves in 728 normal adolescents aged 8-19. The results showed that the distribution of the concave type was the highest among 4 types of F-V curve configuration with a range of 40%-70%. Its tau t features were tau t75 > tau t50 > tau t25 and magnitude of tau t75 > 1s. Then the concave type and its tau t features were called "adolescent fashion". Contrastedly, the distribution of the convex type was the lowest, only 4%-22%. The mechanical mechanism responsible for the formation of the concave type was analysed with the wave-speed theory. During the growth of adolescents, the lung elastic pressure and driving pressure increase with age. The diameters of airways increase, especially those of the peripheral airways with profuse branches. These changes lead to a decrease of resistance. Therefore, the critical flow (Vc) or wave-speed flow (Vmax) of peripheral airways is raised, and the flow there-in could hardly be limited. Thus the choke point (CP) will stay in trachea for a longer period, leading to the elongation of the plateau towards the tail or the concavity of the curve towards the volume axis and hence the formation of the concave type.

Adolescent↗

PubMed1998

[Characteristics of F-V curve configuration and its tangent time constants and its wave-speed mechanism in normal humans above 50 years old].

To understand the characteristics of F-V curve configuration and its tangent time constant (tau 1) in normal humans above 50 years old, the tau 1 at high, mid, low lung volumes (tau 175, tau 150, tau 125) were measured from F-V curves for 135 normal humans aged 50-84. The results showed that the convex type was the most frequent one (40%-75%) among the 4 types of F-V curve and its tau 1 characteristics were tau 175 > tau 150 < tau 125 and magnitude of tau 175 < 1s; on the other hand, the concave type was the least frequent one (0.18%). These suggested that the convex type and its tau 1 characteristics might be the changes in senility. Further, the mechanical mechanism for the convex type of F-V curve configuration was explored.

Age Factors↗

PubMed1998

[Determination of airway resistance with the interruption technique in 300 normal adolescents].

The airway resistance (Raw) was determined with interruption technique in 300 normal adolescents aged 12 to 19 years on the RM-6000 polygraph system. FVC, V75, V50, V25 were also measured. The regression equations of expiratory and inspiratory resistances were built with multiple stepwise regression analysis on the IBM-PC/XT computer with age, height and FVC as independent variables. The results showed that both expiratory and inspiratory resistances decreased with age and negatively correlated with height and FVC, but FVC, V75, V50, V25 increased with age. These reflected that Raw declined with the growth and development of the lung and airway proportionally. This fact is correspondent with some international investigations. The rules and regression equations of Raw variation during the growth of adolescents for Chinese presented in this paper can be put to use in public health and clinical work.

Adolescent↗

PubMed1998

[A randomized trial of Zudan in the prophylaxis of nausea and vomiting induced by cisplatin].

OBJECTIVE: To study the anti-emetic effect of Zudan on high-dose cisplatin and its toxicity. METHODS: A randomized, crossover assay was used in thirty patients who received cisplatin chemotherapy to compare the efficacy and the toxicity of identical dose of Zudan and Zofran. RESULTS: The response rate of acute vomiting induced by cisplatin was 70.0% in patients receiving Zudan and 63.3% in those receiving Zofran. Complete response rate was 56.7% in Zudan arm and 53.3% in Zofran arm. The two arms were not remarkably different in response rates or adverse reactions. CONCLUSION: Zudan is safe and effective in the control of vomiting induced by cisplatin.

Adolescent↗

PubMed1998

[Malignant clonogenic precursors in the peripheral blood of patients with multiple myeloma].

OBJECTIVE: To study the clonogenic potential of circulating malignant precursors in the peripheral blood of patients with multiple myeloma (MM). METHODS: A new cell culture system was used to expand putative malignant precursor clones and promote their differentiation. Meanwhile, immunocytochemical staining, Giemsa-Wright staining and scanning electron microscopy were employed to reveal the growth properties and biological features of fresh and expanded malignant precursors and plasmacytes. RESULTS: Small lymphocyte-like B cells, which were actively proliferative and grew in the form of clusters, were found at the third day after culture. They accounted for 38% +/- 14%. The cells didn't express cytoplasmic immunoglobulin (CyIg) and CD38 antigen. In addition, no typical plasmacytes were observed. At the sixth day of culture, morphologically discernible plasmacytes, which grew in the form of large clumps in this culture system, were detected and represented 58% +/- 8%. These plasmacytes strongly expressed CD38 antigen and monoclonal CyIg identical to that of the original myeloma cells. CONCLUSION: Malignant clonogenic precursor cells, which have high proliferative potential, are present in the peripheral blood of MM cases, and could proliferate and differentiate into myeloma cells.

Adult↗

PubMed1998

[Antiandrogen treatment for nude mice model with ectopic transplanted human HCC].

OBJECTIVE: To investigate the effect of antiandrogen on hepatocellular carcinoma (HCC). METHODS: Nude mice model with orthotopic transplanted human HCC was constructed and the androgen receptor (AR) in tumor and surrounding liver tissue was assayed dynamically. Nude mice with ectopic transplanted HCC were treated with flutamide (blocker of AR) at two different dosages (Group F1, F2), normal saline(Group C), and anticancer drug(Group M). The effect of treatments was compared among the groups. RESULTS: The quantity of AR in nucleus and cytoplasm in tumor and tumor-surrounding tissue decreased with the increasing size of tumor in proper order. AR in tumor was significantly less in F1 and F2 groups than in other groups. The tumor weight of group F1, F2 and C had no significant difference (1.36 +/- 0.82 g, 2.66 +/- 1.40 g, 1.66 +/- 0.79 g, respectively), but was significantly higher than that of group M. CONCLUSION: Androgen may play a role at the initial stage of hepatocarcinogenesis, and antiandrogen therapy may be ineffective in the established tumor.

Androgen Antagonists↗