Biomedical subjects

H Gong

Publications and source records attributed to H Gong.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Impact of high temperature on testicular growth and development of valuable silkworm Antheraea yamamai(Lepidoptera: Saturiidae)].

The results indicated that high temperature had a significant impact on the growth and development of testis in Japanese oak silkworm Antheraea yamamai. The testicular size of the 3rd and 4th instar larvae increased within the range from 20 to 29 degrees C, and slightly decreased at 32 degrees C. While in the 5th instar, it decreased within the range from 20 to 26 degrees C, with the biggest size at 20 degrees C. The testis was almost hard to grow and develop because the larvae could not survive at 29 to 32 degrees C. When the mature larvae were treated at 32 degrees C at the beginning of coconing or at the 1st or 6th day of pupating, the growth of testicular size and spermatogenesis were significantly arrested, and the sperm number and the content of soluble protein in the testis markedly decreased. When the male moth of the 1st day was treated at 32 degrees C, the activity of the sperms in the testis obviously decreased, in contrast to the treatment at 20 degrees C. It is concluded that for the egg raising of the silkworm, its mature larvae, puape in cocoons and male moths should not be exposed to 32 degrees C from cocooning to adult stage. The proper temperature for rearing 3rd, 4th and 5th instar larvae was discussed.

Animals↗

PubMed2000

[Treatment of hemangioma in oral and maxillofacial region with pingyangmycin injection].

OBJECTIVE: To investigate the indication and result in hemangioma in oral and maxillofacial region with Pingyangmycin injection. METHODS: 1282 patients (554 males and 728 females) with hemangioma in oral and maxillofacial region have been treated in our hospital during the 10-year period from May 1990 to March 1999. The patients range between 0.5-84 years old. Lip, cheek and tongue were usually involved. 1211 patients were treated with injection of Pingyangmycin(about 0.89 mg/ml) and dexamethasone (about 0.55 mg/ml), 1 time/1-2 weeks. RESULTS: The curative rates of cavernous hemangioma and strawberry hemangioma were 93.87% and 84.90%, but that of plexiform hemangioma was 22.22% and those of portwine stain and central hemangioma of the jaws were 0%, respectively. Serious complications associated with Pingyangmycin injection, such as pulmonary fibrosis were not seen. CONCLUSION: Injection of Pingyangmycin is selective primary method for cavernous and strawberry hemangioma treatment.

Adolescent↗

PubMed2000

Factors affecting the stability of the performance of ambient fine-particle concentrators.

This article describes a systematic evaluation of factors affecting the stability of the performance of Harvard ambient fine-particle concentrators, an essential requirement for controlled animal and human exposure studies that utilize these technologies. Phenomenological problems during the operation of the concentrator, including pressure drop increase and decrease in concentration enrichment, were statistically correlated with ambient air parameters such as temperature, relative humidity, PM2.5 mass concentration, and mass median diameter. The normalized hourly pressure drop across the concentrator was strongly associated (R2 = .81) with the product of ambient PM2.5 mass concentration and the difference between the vapor pressure downstream of the impactor nozzle and the saturation vapor pressure at the adiabatic expansion temperature (i.e., the temperature of the aerosol immediately downstream of the virtual impactors). From multiple regression analysis, the average enrichment factor was predicted reasonably well (R2 = .67) by aerosol mass median diameter and the normalized hourly pressure drop. Based on these results, we can anticipate in any given day whether an exposure study can be conducted without a considerable increase in the concentrator pressure drop, which might lead to an abrupt or premature termination of the exposure. As particle mass concentration and ambient dewpoint are the two main parameters responsible for raising the pressure drop across the concentrator, efforts should be made to either desiccate the ambient aerosol at days of high dewpoints, or to dilute the ambient PM at days of high concentrations, prior to drawing the aerosol through the virtual impactors. The latter approach is recommended on days of severe ambient pollution conditions because it is simpler and also makes it possible to maintain the appropriate concentration level delivered to the exposure chamber.

Air Pollutants↗

PubMed1999

Adenosinergic modulation of rat basal forebrain neurons during sleep and waking: neuronal recording with microdialysis.

1. The cholinergic system of the basal forebrain (BF) is hypothesized to play an important role in behavioural and electrocortical arousal. Adenosine has been proposed as a sleep-promoting substance that induces sleep by inhibiting cholinergic neurons of the BF and brainstem. However, adenosinergic influences on the activity of BF neurons in naturally awake and sleeping animals have not been demonstrated. 2. We recorded the sleep-wake discharge profile of BF neurons and simultaneously assessed adenosinergic influences on wake- and sleep-related activity of these neurons by delivering adenosinergic agents adjacent to the recorded neurons with a microdialysis probe. Discharge rates of BF neurons were recorded through two to three sleep-wake episodes during baseline (artificial cerebrospinal fluid perfusion), and after delivering an adenosine transport inhibitor (s-(p-nitrobenzyl)-6-thioinosine; NBTI), or exogenous adenosine, or a selective adenosine A1 receptor antagonist (8-cyclopentyl-1, 3-dimethylxanthine; CPDX). 3. NBTI and adenosine decreased the discharge rate of BF neurons during both waking and non-rapid eye movement (NREM) sleep. In contrast, CPDX increased the discharge rate of BF neurons during both waking and NREM sleep. These results suggest that in naturally awake and sleeping animals, adenosine exerts tonic inhibitory influences on BF neurons, supporting the hypothesized role of adenosine in sleep regulation. 4. However, in the presence of exogenous adenosine, NBTI or CPDX, BF neurons retained their wake- and sleep-related discharge patterns, i.e. still exhibited changes in discharge rate during transitions between waking and NREM sleep. This suggests that other neurotransmitters/neuromodulators also contribute to the sleep-wake discharge modulation of BF neurons.

Adenosine↗

PubMed1999

Sleep-waking discharge of neurons in the posterior lateral hypothalamus of the albino rat.

The sleep-waking discharge patterns of neurons in the posterior lateral hypothalamus (PLH) were investigated in the rat. Previous studies in the cat demonstrated that this region contained neurons that fired tonically at low rates (2-4 Hz) during waking, decreased firing in non-rapid eye-movement (NREM) sleep and nearly ceased firing during rapid eye-movement (REM) sleep. These "REM-off" neurons were proposed to be histaminergic neurons of the tuberomammillary nucleus (TM). Since many anatomical and physiological studies are performed in the rat, we sought to examine the sleep-waking discharge of these neurons in this animal. We found three main types of discharge patterns among PLH neurons. Waking-related neurons decreased their discharge in NREM sleep, and remained at low rates during REM sleep. A subpopulation of these neurons discharged very little during REM sleep (<0.2 Hz) (REM-off neurons). Waking/REM-related neurons decreased their discharge in NREM sleep and returned to waking rates in REM sleep. REM-related neurons decreased their discharge in NREM sleep and increased their discharge during REM sleep higher than waking rates. No NREM-related discharge patterns were recorded. Waking-related and waking/REM-related neurons were similar in location within the PLH and action potential duration. Some REM-off and other waking-related neurons were recorded within the boundaries of the histaminergic TM, however, not all waking-related and REM-off neurons were found within this region. Furthermore, neurons with waking/REM-related and state-indifferent discharge patterns were localized within the TM. These results suggest that waking-related and/or REM-off neurons may not be exclusively histaminergic in rats.

Animals↗

PubMed1999

Arginine deiminase inhibits cell proliferation by arresting cell cycle and inducing apoptosis.

We have previously demonstrated that arginine deiminase inhibits the proliferation of vascular endothelial cells, but the mechanisms leading to growth inhibition have remained unclear. We report here that low concentrations of arginine deiminase purified from Mycoplasma arginini inhibit proliferation of various cultured cells by arresting the cell cycle in G(1) and/or S phase with higher arginine deiminase concentrations leading to subsequent apoptosis. Our results demonstrate that arginine deiminase inhibits cell proliferation not only by depletion of arginine, but also by mechanisms involving the cell cycle and death signals.

Apoptosis↗

PubMed1999

Xenopus laevis sperm receptor gp69/64 glycoprotein is a homolog of the mammalian sperm receptor ZP2.

Little is known about sperm-binding proteins in the egg envelope of nonmammalian vertebrate species. We report here the molecular cloning and characterization of a recently identified sperm receptor (gp69/64) in the Xenopus laevis egg vitelline envelope. Our data indicate that the gp69 and gp64 glycoproteins are two glycoforms of the receptor and have the same number of N-linked oligosaccharide chains but differ in the extent of O-glycosylation. The amino acid sequence of the receptor is closely related to that of the mouse zona pellucida protein ZP2. Most of the sequence conservation, including a ZP domain, a potential furin cleavage site, and a putative transmembrane domain are located in the C-terminal half of the receptor. Proteolytic cleavage of the gp69/64 protein by a cortical granule protease during fertilization removes 27 amino acid residues from the N terminus of gp69/64 and results in loss of sperm binding to the activated eggs. Similarly, we find that treatment of eggs with type I collagenase removes 31 residues from the N terminus of gp69/64 and has the same effect on sperm binding. The isolated and purified N terminus-truncated receptor protein is inactive as an inhibitor of sperm-egg binding. Earlier studies on the effect of Pronase digestion on receptor activity suggest that this N-terminal peptide may contain an O-linked glycan that is involved in the binding process. Based on these results and the findings on the primary structure of the receptor, a pathway for the maturation and secretion of gp69/64, as well as its inactivation following fertilization, is proposed.

Amino Acid Sequence↗

PubMed1999

Optic nerve changes in manganese-deficient rats.

In the present study the changes in the optic nerve due to dietary manganese (Mn) deficiency has examined in Wistar Kyoto rats, since there is a lack of information on the significance of manganese in the optic nerve. After 5 months on a Mn-deficient diet, the optic nerve was examined by light and transmission electron microscopy. The serum manganese level of the deficient rats was significantly lower than that of the controls. The light microscopic findings showed significantly fewer myelinated axons in the Mn-deficient rats and Mn-recovery rats than in the control group, and there were obviously more oligodendrocytes in the recovery rats. Ultrastructural findings were: significantly decreased diameters and lamellae of myelinated axons in the optic nerves of the Mn-deficient rats and abnormal mitochondria in the axons. Rats fed a normal diet for 3 months after 5 months on a Mn deficient diet had a normal serum manganese level, but no change in the abnormal morphology of the myelinated axons. It is concluded that the optic nerve needs manganese for the maintenance of its cell structure.

Animals↗

PubMed1999

Eosinophilic granuloma (Kimura's disease) of the orbit: a case report.

BACKGROUND: Eosinophilic granuloma of the soft tissue, Kimura's disease, is a benign slow-growing tumor that is manifested clinically by one or more inflammatory nodules involving mainly the face and scalp, but rarely the eye. CASE REPORT: The patient was a 32-year-old male with swelling of the left lower eyelid, marked peripheral blood eosinophilia and increased serum immunogloblin E. MRI revealed swelling of all rectus muscles of the left eye, but no tumor mass. Corticosteroid treatment reduced the swelling of the eyelid, but it recurred after corticosteroid was discontinued. Eight years later the patient returned with a complaint of increased swelling of the left lower eyelid. An elastic, nontender, soft tumor mass was palpable subcutaneously in the left lower eyelid extending into the orbit. MRI revealed a tumor mass in the left orbital space. The parotid gland was also swollen and palpable. Both tumors were resected surgically, and histopathological study revealed prominent proliferation of lymphoid follicles with germinal centers showing interfollicular infiltration by eosinophils. The pathological findings in the parotid gland were similar. The diagnosis was Kimura's disease. CONCLUSION: This patient is unique in that he had no tumor at the first examination, only swelling of the rectus muscles, and a tumor mass appeared many years later. Unilateral swelling of the rectus muscles may be one of the first signs of Kimura's disease. Not only tumor but also swelling of the rectus muscles limited ocular movement.

Adult↗

PubMed1999

Apoptosis of the hyaloid artery in the rat eye.

The hyaloid artery is a vestigial vessel situated on the optic nerve extending to the posterior surface of the lens in the vitreous cavity of the eye. We studied the nature and pattern of cell death during regression of the hyaloid artery. The cells comprising the hyaloid artery appear to be alive for 20 days after birth in the rat, and cell death during regression of the hyaloid artery has the characteristics of apoptosis. We observed apoptotic bodies containing condensed chromatin and identified the hyaloid vessels as targets of macrophage-mediated remodelling. Using the "TUNEL method" for labeling fragmented DNA in vascular cells, we assessed the pattern of apoptotic cell death during hyaloid artery regression. Our study demonstrated the appearance of apoptosis in pericytes as well as endothelial cells during regression in the vasculature. In pericytes, apoptosis appeared to begin or to occur more frequently than in endothelial cells. Both morphological and TUNEL analyses indicated that capillary apoptosis occurs mainly from day 10 to day 20 after birth rather than from the 1st day. Macrophages were present near the hyaloid artery and these may influence apoptosis.

Aging↗

PubMed1999

Changes in manganese superoxide dismutase expression after exposure of the retina to intense light.

Manganese superoxide dismutase (Mn-SOD) is a naturally-occurring scavenger of superoxide, one of several reactive oxygen intermediates. To determine if Mn-SOD expression is enhanced as a defensive mechanism against oxidative challenges, such as intense light exposure, rats were exposed to cyclic light (80 lux) for 2 weeks, intense light (1,800 lux) for 24 h, and then again to cyclic light. Experimental and control (exposed to cyclic light only) eyes were enucleated 3 h, 1, 3, 7, and 14 days after light challenge. Protein expression was examined immunohistochemically using rabbit antisera against rat Mn-SOD. There was no significant difference between the light-exposed and the control groups in the thickness of the outer nuclear layers. Both retinal pigment epithelial cells and photoreceptor inner segments in the normal retina were labeled for Mn-SOD. Mn-SOD labeling was lost 3 h and day 1 after light challenge. It was re-expressed in the retinal pigment epithelial cells 3, 7, and 14 days after the light challenge, and in the photoreceptor inner segments after day 14. These results suggest that the retina might have a protective potential against light damage, in which Mn-SOD may play an important role.

Animals↗

PubMed1999

Day-to-day particulate exposures and health changes in Los Angeles area residents with severe lung disease.

We measured particulate matter (PM2.5 and PM10) exposures, home temperature, arterial blood oxygen saturation, blood pressure, and lung function in 30 volunteer Los Angeles area residents during four-day intervals. Continuous Holter electrocardiograms were recorded in a subgroup on the first two days. Subjects recorded symptoms and time-activity patterns in diaries during monitoring, and during a reference period one week earlier/later. All subjects had severe chronic obstructive pulmonary disease. PM10 (24-hr mean) at monitoring stations near subjects' homes averaged 33 micrograms/m3, and ranged from 9 to 84 micrograms/m3. In longitudinal analyses, day-to-day changes in PM2.5 and PM10 outside subjects' homes significantly tracked concurrent station PM10 (r2 = 0.22 and 0.44, respectively). Indoor and personal concentrations were less related to station readings (r2 < or = 0.1), but tracked each other (r2 > or = 0.4). In-home temperatures tracked outdoor temperatures more for lows (r2 = 0.27) than for highs (r2 = 0.10). These longitudinal relationships of subject-oriented and station PM measurements were generally similar to cross-sectional relationships observed previously in similar subjects. Among health measurements, only blood pressure showed reasonably consistent unfavorable longitudinal associations with particulates, more with station or outdoor PM than with indoor or personal PM.

Aged↗

PubMed1999

Corneal changes in manganese-deficient rats.

PURPOSE: This study was undertaken to examine the changes in the cornea due to dietary manganese (Mn) deficiency in Wistar-Kyoto rats, because there is a lack of information on the significance of manganese in the cornea. METHODS: Mature female Wistar-Kyoto albino rats were mated with males. All pregnant females were divided into Mn-deficient and control groups. The offspring were fed a Mn-deficient diet. When they reached age 3 months, Mn-deficient females were mated with Mn-deficient males. The offspring of this second generation of Mn-deficient rats continued to be fed on the Mn-deficient diet and were used for the experiment. The corneas were examined at age 2 months. After 3 months on a Mn-deficient diet, the rats were given a normal diet for a 3-month recovery experiment. The corneas were examined by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). RESULTS: TEM revealed very few microvilli and bundles of tonofibrils and abnormal mitochondria in the corneal epithelium of Mn-deficient rats. The stroma was thin, and collagen fibers were decreased prominently in diameter. Descemet's membrane was thinner than in the control group. SEM showed many fewer microvilli in the Mn-deficient rats and more dark cells in the most superficial layer of epithelium. SEM also showed endothelial cells with a pentagonal instead of a hexagonal shape in Mn-deficient rats. Rats fed a normal diet for 3 months after Mn deficiency showed a normal serum Mn level and almost normal corneal structure. CONCLUSION: This study suggested that the cornea needs Mn for the maintenance of its cell structure.

Animals↗

PubMed1999

The 21st century environment and air quality influences on asthma.

"Criteria" air pollutants are federally regulated pollutants that occur widely outdoors and have diverse sources, most often related to combustion. They include ozone (O3), particulate matter, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and lead. All except lead may interfere with oxygen delivery, and so may be of special concern to asthmatics. In controlled experiments, SO2 causes acute asthma symptoms and bronchoconstriction, preventable by beta-agonist medications. Ozone causes acute irritant symptoms, restrictive lung dysfunction, increased bronchial reactivity, and lower-airway inflammation in healthy people and asthmatics. Exposures to O3, and possibly to other pollutants, appear to exacerbate bronchoconstrictive or inflammatory responses to inhaled aeroallergens (bioaerosols); this may represent an important health risk to asthmatics. Exposure levels known to evoke acute responses to O3 or SO2 are uncommon in community air pollution; however, some asthmatics might be susceptible to lesser, more common exposures. Evidence concerning NO2 is equivocal, but it may have O3-like effects in some asthmatics. Epidemiology has often associated particulate pollution with asthma exacerbations and other cardiorespiratory illnesses, even in cities with relatively mild air pollution. Current laboratory research cannot fully explain this association. Advances in emission controls should further reduce ambient pollution levels, but probably will not reduce asthma morbidity. Better asthma management, with improved anti-inflammatory medications, more careful monitoring by patients and health care providers, and reasonable efforts to reduce pollutant and aeroallergen exposures, offers the best hope to reduce asthma morbidity in the new century.

Air Pollutants↗

PubMed1999

Room airflow studies using sonic anemometry.

To ensure prompt response by real-time air monitors to an accidental release of toxic aerosols in a workplace, safety professionals should understand airflow patterns. This understanding can be achieved with validated computational fluid dynamics (CFD) computer simulations, or with experimental techniques, such as measurements with smoke, neutrally buoyant markers, trace gases, or trace aerosol particles. As a supplementary technique to quantify airflows, the use of a state-of-the art, three-dimensional sonic anemometer was explored. This instrument allows for the precise measurements of the air-velocity vector components in the range of a few centimeters per second, which is common in many indoor work environments. Measurements of air velocities and directions at selected locations were made for the purpose of providing data for characterizing fundamental aspects of indoor air movement in two ventilated rooms and for comparison to CFD model predictions. One room was a mockup of a plutonium workroom, and the other was an actual functioning plutonium workroom. In the mockup room, air-velocity vector components were measured at 19 locations at three heights (60, 120 and 180 cm) with average velocities varying from 1.4 cm s-1 to 9.7 cm s-1. There were complex flow patterns observed with turbulence intensities from 39% up to 108%. In the plutonium workroom, measurements were made at the breathing-zone height, recording average velocities ranging from 9.9 cm s-1 to 35.5 cm s-1 with turbulence intensities from 33% to 108%.

Aerosols↗

PubMed1999

Effect of spirometer temperature on FEV1 in a longitudinal epidemiological study.

OBJECTIVES: To assess the magnitude of error in pulmonary function measurements introduced by variation in spirometer temperature under field conditions. In a large scale epidemiological study of school children, the influence was investigated of spirometer temperature on forced expiratory volume in 1 second (FEV1) measured with dry rolling seal volumetric spirometers and conventional body temperature, pressure, and saturation (BTPS) corrections. METHODS: Linear regression analyses were performed on data from 995 test-retest pairs on 851 different children, with 1-110 days between test and retest, and spirometer temperature differences between -13 degrees C and +9 degrees C. RESULTS: After adjusting for effects of growth (test-retest intervals) and circadian variation (changes in times of testing), differences in standard BTPS corrected FEV1 showed significant (p < 0.05) dependence on differences in spirometer temperature between tests (-0.24%/degree C). CONCLUSIONS: When spirometer temperatures vary widely, standard BTPS correction does not fully adjust for gas contraction. To improve accuracy of volume measurements in epidemiological studies, additional correction for variation in spirometer temperature should be considered.

Adolescent↗

PubMed1999

A study of twelve Southern California communities with differing levels and types of air pollution. I. Prevalence of respiratory morbidity.

To study possible chronic respiratory effects of air pollutants, we initiated a 10-yr prospective cohort study of Southern California children, with a study design focused on four pollutants: ozone, particulate matter, acids, and nitrogen dioxide (NO2). Twelve demographically similar communities were selected on the basis of historic monitoring information to represent extremes of exposure to one or more pollutants. In each community, about 150 public school students in grade 4, 75 in grade 7, and 75 in grade 10 were enrolled through their classrooms. Informed consent and written responses to surveys about students' lifetime residential histories, historic and current health status, residential characteristics, and physical activity were obtained with the help of the parents. In the first testing season, 3,676 students returned questionnaires. We confirmed associations previously reported between respiratory morbidity prevalence and the presence of personal, demographic, and residential risk factors. Rates of respiratory illness were higher for males, those living in houses with pets, pests, mildew, and water damage, those whose parents had asthma, and those living in houses with smokers. Wheeze prevalence was positively associated with levels of both acid (odds ratio [OR] = 1.45; 95% confidence interval [CI], 1.14-1.83) and NO2 (OR = 1.54; 95% CI, 1.08-2.19) in boys. We conclude, based on this cross-sectional assessment of questionnaire responses, that current levels of ambient air pollution in Southern California may be associated with effects on schoolchildren's respiratory morbidity as assessed by questionnaire.

Acids↗

PubMed1999

A study of twelve Southern California communities with differing levels and types of air pollution. II. Effects on pulmonary function.

To study the possible chronic respiratory effects of air pollutants, we designed and initiated a 10-yr prospective study of Southern California public schoolchildren living in 12 communities with different levels and profiles of air pollution. The design of the study, exposure assessment methods, and survey methods and results related to respiratory symptoms and conditions are described in the accompanying paper. Pulmonary function tests were completed on 3,293 subjects. We evaluated cross-sectionally the effects of air pollution exposures based on data collected in 1986-1990 by existing monitoring stations and data collected by our study team in 1994. Expected relationships were seen between demographic, physical, and other environmental factors and pulmonary function values. When the data were stratified by sex, an association was seen between pollution levels and lower pulmonary function in female subjects, with the associations being stronger for the 1994 exposure data than the 1986-1990 data. After adjustment, PM10, PM2.5, and NO2 were each significantly associated with lower FVC, FEV1, and maximal midexpiratory flow (MMEF); acid vapor with lower FVC, FEV1, peak expiratory flow rate (PEFR), and MMEF; and O3 with lower PEFR and MMEF. Effects were generally larger in those girls spending more time outdoors. Stepwise regression of adjusted pulmonary function values for girls in the 12 communities showed that NO2 was most strongly associated with lower FVC (r = -0.74, p < 0.01), PM2.5 with FEV1 (r = -0.72, p < 0.01), O3 with PEFR (r = -0.75, p < 0.005), and PM2.5 with MMEF (r = -0.80, p < 0.005). There was a statistically significant association between ozone exposure and decreased FVC and FEV1 in girls with asthma. For boys, significant associations were seen between peak O3 exposures and lower FVC and FEV1, but only in those spending more time outdoors. These findings underline the importance of follow-up of this cohort.

Acids↗