Purification and partial characterization of thermal hysteresis proteins from overwintering larvae of pine needle gall midge, Thecodiplosis japonensis (Diptera: cecidomiidae)

The pine needle gall midge of Thecodiplosis japonensis is a serious forest pest and overwinters as a 3rd instar larva at soil surface in Korea. The time necessary for killing 50% of larvae at -15 degree C is 160 min. During overwintering period, T. japonensis larvae accumulate relatively high content of trehalose as the main cryoprotectant. In this paper, the proteinaceous cryoprotectants were identified. Two thermal hysteresis proteins (THP-1S and 2S) were purified from overwintering larvae by ethanol fractionation, trichloroacetic acid precipitation, ion-exchange chromatography (DEAE-Sephadex A-25) and gel permeation chromatography (Sephadex G-100). Their molecular weights are 34.9 and 37.8 kD respectively. T. japonensis THPs cannot be stained by periodic acid-Schiffs' reagent, suggesting no carbohydrate in them. The thermal hysteresis activity of THP-2 at the concentration of 50 mg/ml is 11.02 +/- 0.08 degree C (mean +/- SD, n=10), perhaps the highest active insect THP. It is the first report of purified T. japonensis THPs in Diptera.

A simple sample preparation for enhancing the sensitivity of mass spectrometric oligosaccharide determinations through the use of an adsorptive hydrophobic resin

A simple microadsorption technique is described to remove detergent additives from oligosaccharide samples before their mass spectrometric analysis. The described methodology has been validated with submicrogram quantities of contaminated glycoproteins. This procedure is applicable to investigating minute quantities of glycans in both the positive- and negative-ion mode of matrix-assisted laser desorption/ionization mass spectrometry.

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.

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.

[The principles of use of antibiotic drugs in plastic surgery: a preliminary exploration]

OBJECTIVE

To investigate the use of antibiotic drugs in the plastic surgery patients.

METHODS

With a random-sampling method, the patterns of use of antibiotic drugs were reviewed in 840 cases (1014 surgical operations) from the Plastic Surgery Hospital, the Chinese Academy of Medical Sciences.

RESULTS

About 99.21 per cent of patients received antibiotic drugs, and prophylaxis accounted for about 99.70 per cent of all antibiotic drugs. The drugs used most often for prophylaxis were penicillin, followed by cephalosporins.

CONCLUSION

By analysing the data, it is clearly shown that there exist abuse and inappropriate use of antibiotic drugs. Surgeons must keep in mind that antibiotic prophylaxis should be used with appropriate indications, optimum time and duration.

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.

A novel recombinant adeno-associated virus vector packaging system with HSV-1 amplicon providing helper functions

A novel packaging system for producing recombinant adeno-associated virus (rAAV) vector was described. Instead of the conventional method for rAAV production by two-plasmid co-transfection followed by superinfection with adenovirus 5, an HSV-1 amplicon system expressing AAV-2 rep and cap genes from their native promoters was used to provide complete helper functions for rAAV replicating and packaging. This HSV-1 amplicon stock consisted of two kinds of infectious HSV-1 virions, a replicating-defective HSV-I amplicon pseudovirus harboring multi-copies of AAV-2 rep and cap gene and a temperature-sensitive HSV-1 mutant strain ts-KOS. High-titer rAAV was generated with this new packaging system. This packaging system gives a simple and scaleable process for rAAV production.

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.

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.

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.

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.

Effects of Na-K-2Cl cotransport regulators on outflow facility in calf and human eyes in vitro

PURPOSE

Cultured human trabecular meshwork (TM) cells possess substantial Na-K-Cl activity, which is involved in the regulation of TM cell volume. The hypothesis in the present study was that drugs that affect the cotransporter might alter aqueous humor outflow facility (C) in the intact eye. The effects of agents and conditions known to modulate Na-K-CI cotransport activity and/or TM cell volume on C in perfused anterior segments were investigated.

METHODS

Human and calf eyes were dissected and perfused, and C was determined according to standard published methods. Perfusates with modified osmolarity were used to cause alterations in TM cell volume. Cl-free perfusate and/or bumetanide (10(-5) M) was used to inhibit Na-K-Cl cotransport activity, and vasopressin (10(-7) M, 10(-8) M) was used to stimulate cotransport activity.

RESULTS

In human eyes, hypo-osmotic perfusate decreased C 12%, whereas hyper-osmotic perfusate increased C 44%. These changes lasted approximately 30 minutes, after which C began to normalize. Inhibition of Na-K-Cl cotransport using Cl-free medium or bumetanide resulted in facility increases of 27% and 22%, respectively. There was an additive increase in C with bumetanide plus Cl-free media. Stimulating Na-K-Cl cotransport with 10(-8)M and 10(-7)M vasopressin resulted in 28% and 35% decreases in C, respectively. The results were similar in calf eyes: Cl-free medium or bumetanide resulted in 41% and 52% increases in C, whereas 10(-8) M and 10(-7) M vasopressin resulted in 14% and 19% decreases in C, respectively.

CONCLUSIONS

Modulation of Na-K-Cl cotransport results in changes in C that may be mediated in part by cell volume changes.

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.

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%.

A theoretical basis for investigating ambient air pollution and children's respiratory health

Acute respiratory health effects in children from exposure at current ambient levels of ozone are well documented; however, evidence for acute effects from other criteria pollutants such as nitrogen dioxide and respirable particles is inconsistent. Whether chronic effects result from long-term exposure to any of these pollutants during childhood is an important unresolved question. Establishing whether acute or chronic effects result from childhood exposure and identifying sensitive subgroups may require integration of biologic mechanisms of lung defenses, injury, and response into the study design and statistical models used in analyses. This review explores the theoretical basis for explaining such adverse effects in light of our contemporary understanding of mechanisms of lung injury and response at the cellular and molecular levels. The rapidly evolving understanding of the effects of air pollution on cellular and molecular levels presents an opportunity to develop and refine innovative biologically based hypotheses about the effects of childhood exposure. We hypothesize that children with low fruit and vegetable intake, low antioxidant levels, high polyunsaturated fat intake, or who have inherited certain alleles for genes involved in lung defenses and immune response regulation may be at increased risk for adverse effects. Because responses to air pollutants of interest are complex and involve a number of pathophysiologic processes, the magnitude of main effects of dietary factors, genes, and gene-environment interactions may be modest for individuals; however, each may make an important contribution to the population burden of preventable respiratory diseases.

[Helicobacter pylori infection and expression of PCNA, p53, c-erbB-2 in carcinoma and precancerours lesions of the stomach]

OBJECTIVE

To study the role of Helicobacter pylori (Hp) in gastric carcinoma.

METHODS

Hp was examined in 70 patients with gastric carcinoma, 62 patients with pre-malignant lesions and 16 controls by improved Warthin-Starry method and PCNA, p53, cerbB-2 protein examined immunohistochemically.

RESULTS

The frequency of Hp infection in gastric carcinoma and its precusor lesions was significantly higher than that in the controls. There was no significant difference in Hp infection rate between gastric carcinoma and its precursor lesions, nor between the intestinal type and diffuse type of gastric carcinoma. Hp infection correlated well with expressions of PCNA, c-erbB-2 and with co-expression of PCNA, p53 and c-erbB-2 in gastric carcinoma and its precusors. p53 protein was expressed only in gastric carcinoma, and its expression level was higher in the presence than in the absence of Hp infection (P < 0.01).

CONCLUSION

Hp might act as a tumor promoter in the genesis of gastric cancer.

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.

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.

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.

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.

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.

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.

[Expression of transforming growth factor alpha and its relationship with HBV infection in hepatocellular carcinomas]

OBJECTIVE

To assess the expression of TGF alpha in hepatocellular carcinoma and its relationship with HBV infection.

METHODS

Using in situ hybridization and streptavidin-peroxidase immunohistochemistry to detect TGF alpha mRNA, TGF alpha protein and HBV DNA in 53 cases of HCC and 14 cases of controls.

RESULTS

Positive rates of TGF alpha mRNA and TGF alpha protein in carcinoma tissue were 30.2% and 73.6% respectively, which were higher than in normal controls (P < 0.05). The expression of TGF alpha mRNA and TGF alpha protein was increased significantly in dysplastic liver cells (DLC) locating aside from the tumor tissue in comparing with those of non-dysplastic liver cells (NDLC) (P < 0.05). Positive rates of HBV DNA in carcinoma tissue and paratumorous liver tissue were 56.6% and 60.4% respectively, which were higher than in the normal controls (P < 0.001). Positive rate of HBV DNA in the nuclei of tumor tissues, tissue of the dysplastic areas and non-dysplastic areas was lowering down successively (P < 0.05). There was a significant relationship between expression of TGF alpha mRNA and TGF alpha protein in the carcinoma tissues and HBV DNA in the tumorous and its surrounding tissues respectively.

CONCLUSIONS

Expression of TGF alpha in carcinoma tissues was closely associated with the existence of HBV DNA and TGF alpha may participate in the early stage of liver carcinogenesis. The increased expression of HBV DNA in nuclei may serve as an important morphology marker in distinguishing carcinoma from DLC and NDLC.

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.

[Preventive and therapeutic effects of calcium lactate on osteoporosis in aged ovariectomized rats]

Twelve-month-old rats were ovariectomized (OVX), remained untreated for one month. Calcium lactate was given daily by gavage at the dose of 125, 250 and 750 mg/kg(Ca125, Ca250, Ca750) for 3 months. The results showed that compared with OVX rats, Ca250 could markedly increase the bone mineral density (BMD) at right femur. Both Ca250 and Ca750 could markedly enhance the ash weight, ratio of ash weight to dry weight of left femur and ratio of 24-hour urinary Ca/Cr. Ca125 could markedly decrease serum ALP concentration. Both Ca125 and Ca250 could decrease the ratio of 24-hour urinary Hop/Cr. All doses of calcium lactate groups could elevate serum Ca, and were no influence on the volume, wet and dry weight of the left femur and serum OC levels. In conclusion, the administration of calcium lactate to aged OVX rats prevents bone resorption, and its mechanism may be relating to the supplement of calcium properly.

Relationship between acute ozone responsiveness and chronic loss of lung function in residents of a high-ozone community

We hypothesized that acute respiratory responsiveness to ozone predicts chronic lung injury from repeated exposure to ozone-containing air pollution. We tested this hypothesis in 164 middle-aged nonsmoking residents of an ozone-polluted community who underwent lung-function measurements during 1986 and 1987 (i.e., time 3). The time-3 study was a follow up of more comprehensive studies conducted in 1977-1978 (time 1) and in 1982-1983 (time 2). In contrast to the apparent rapid (i.e., approximately 60 ml/y) decline in lung-function measurements between times 1 and 2, our subjects showed little change in forced vital capacity (FVC) or forced expired volume in 1 s (FEV1.0) between times 2 and 3, and they experienced a normal decline between times 1 and 3. A subgroup (n = 45) underwent 2-h laboratory ozone exposures to 0.4 ppm ozone, accompanied by intermittent exercise, and they experienced mild acute reductions in FEV1.0 and FVC, but there was little change in bronchial responsiveness to methacholine. Individual acute responses to laboratory ozone were not correlated with individual long-term changes between times 1 and 3. In summary, the results did not support our initial hypothesis, and they did not confirm rapid function decline in nonsmokers chronically exposed to ozone-containing air pollution.

Cardiovascular effects of ozone exposure in human volunteers

We hypothesized that ozone (O3) exposure acutely affects cardiovascular hemodynamics in humans and, in particular, in subjects with essential hypertension. We studied 10 nonmedicated hypertensive and six healthy male adults. Each subject, after catheterization of the right heart and a radial artery, was exposed in an environmentally controlled chamber to filtered air (FA) on one day and to 0.3 ppm O3 on the following day for 3 h with intermittent exercise. Relative to FA exposure, O3 exposure induced no statistically significant changes in cardiac index, ventricular performance, pulmonary artery pressure, pulmonary and systemic vascular resistances, ECG, serum cardiac enzymes, plasma catecholamines and atrial natriuretic factor, and SaO2. The overall results did not indicate major acute cardiovascular effects of O3 in either the hypertensive or the control subjects. However, mean preexposure to postexposure changes were significantly (p < 0.02) larger with O3 than with FA for rate-pressure product (1,353 beats/min/mm Hg) and for heart rate (8 beats/min); these responses were not significantly different between the hypertensive and the control subjects. Significant O3 effects were also observed for mean FEV1 (-6%), and AaPO2 (> 10 mm Hg increase), which were not significantly different between the two groups. These results suggest that O3 exposure can increase myocardial work and impair pulmonary gas exchange to a degree that might be clinically important in persons with significant preexisting cardiovascular impairment, with or without concomitant lung disease.

[A novel gene delivery system targeting to epidermal growth factor receptor overexpressing cancer cells]

A polypeptide with 33 amino acid residues was designed and synthesized. Its C terminal was composed of multiple lysine residues, which played as a DNA condensing agent, whereas the N terminal was the receptor binding domain of Epidermal Growth Factor(N32-K48). Through a spontaneous self-assembly process with electrostatic interaction, the synthetic peptide combined with a luciferase expression vector, pEBluc, to form an EGF receptor targeting nucleic acid complex. Significant luciferase activity was detected 48 hours after adding this complex directly to the culture medium of the A431 cells. This synthetic peptide could be used to construct a gene transfer system mediated by the endocytosis via EGF receptor. It promoted a very possibility of the gene therapy for the cancers such as glioma, melanoma and squamous carcinoma which are known of epidermal growth factor receptor overexpression.

p75NTR and Trk receptors are expressed in reciprocal patterns in a wide variety of non-neural tissues during rat embryonic development, indicating independent receptor functions

The p75 kDa neurotrophin receptor (p75NTR) has been detected in a number of non-neural tissues, especially during development. Reports of Trk receptor transcripts in non-neural tissues raise the possibility that the sites of p75NTR expression during development may correlate with Trk receptor expression. Coexpression of p75NTR with the Trk receptors in developing non-neural tissues would support the hypothesis that there is a cooperative function between the two receptor subclasses. To address these questions, p75NTR was localized relative to the three known Trk receptors in adjacent sections of rat embryos at stages of development when the highest levels of p75NTR have been observed in the muscle, maxillary pad, kidney, and lung. Using in situ hybridization and immunhistochemical analyses, we show here that the Trk receptors are expressed extensively in non-neural tissues during cell differentiation and tissue morphogenesis but in patterns that are generally reciprocal to that of p75NTR. The results indicate p75NTR most likely functions independently of the Trk receptors in most developing non-neural tissues. However, the p75NTR consistently appears in non-neural cells adjacent to those expressing Trk receptors. The reciprocal patterns of expression indicate that the separate activities of the two receptors most likely complement each other in regulating cell-cell interactions important for the innervation of developing non-neural tissues.

Inhibition of JAK3 and STAT6 tyrosine phosphorylation by the immunosuppressive drug leflunomide leads to a block in IgG1 production

Leflunomide is an immunosuppressive drug capable of inhibiting T and B cell responses in vivo. A number of studies demonstrate that leflunomide functions both as a pyrimidine synthesis inhibitor and as a tyrosine kinase inhibitor. We previously reported that leflunomide inhibits LPS-stimulated B cell proliferation, cell cycle progression, and IgM secretion. This inhibition can be reversed by the addition of exogenous uridine, suggesting that leflunomide functions as a pyrimidine synthesis inhibitor in B cells. We report here that while the addition of uridine restored proliferation and IgM secretion to leflunomide-treated LPS-stimulated B cells, as determined by metabolic labeling and immunoprecipitation, it did not completely restore secretion of IgG Ab. We hypothesized that leflunomide inhibits LPS-induced IgG secretion by inhibiting tyrosine kinase activity required for isotype switch. We tested this hypothesis in a well-defined model of isotype switch, LPS plus IL-4 induction of IgG1. Leflunomide inhibited IgG1 secretion in this model in a dose-dependent manner. The signal transduction pathway utilized by IL-4 to induce IgG1 involves tyrosine phosphorylation of the IL-4 receptor, JAK1, JAK3, and STAT6 proteins induced by IL-4 binding to the IL-4R. Leflunomide diminished the tyrosine phosphorylation of JAK3 and STAT6 in the absence or presence of uridine. In gel mobility shift studies, STAT6 binding to the STAT6 DNA binding site in the IgG1 promoter decreased in the presence of leflunomide or leflunomide plus uridine. Taken together, these data suggest that leflunomide acts as a tyrosine kinase inhibitor to block IgG1 production.

Temperature standardization of multiple spirometers

In respiratory health surveys involving multiple spirometers, spirometer differences may introduce important biases. We investigated temperature measurement variability as a cause of spirometer differences. Digital thermometers recorded internal (cylinder) and external (outer casing) temperatures of six similar rolling-seal spirometers during field use and in laboratory tests at controlled room temperatures. Internal and external thermometers substantially agreed in recording spirometer temperature changes, which lagged room temperature changes. Offsets of individual thermometers from overall mean readings were roughly the same in field testing of 3908 students in > 60 schools over 5 months and in subsequent laboratory tests. Thermometers differed by as much as 1.3 degrees C, causing differences as large as 0.8% in vital capacity measurements. We conclude that (1) interior and exterior temperatures of typical rolling-seal spirometers do not differ greatly, although both may differ from surrounding air temperature; and (2) variations between individual digital thermometers may be large enough to bias spirometric data appreciably in large-scale surveys. Variations should be controlled by selection of similar-reading thermometers and/or correction to a uniform standard.

In vitro and in vivo mechanisms of action of the antiproliferative and immunosuppressive agent, brequinar sodium

Intracellular pyrimidine nucleotides (PyN) can be synthesized de novo from glutamine, CO2, and ATP, or they can be salvaged from preformed pyrimidine nucleosides. The antiproliferative and immunosuppressive activities of brequinar sodium (BQR) are thought to be due to the inhibition of the activity of dihydroorotate dehydrogenase, which results in a suppression of de novo pyrimidine synthesis. Here we describe the effects of the pyrimidine nucleoSide, uridine, on the antiproliferative and immunosuppressive activities of BQR. In vitro reduction of PyN levels in Con A-stimulated T cells and inhibition of cell proliferation by low concentrations of BQR (< or =65 microM) are reversed by uridine. However, uridine is unable to reverse the effects of high concentrations of BQR (> or =65 microM). The ability of BQR to induce anemia in BALB/c mice is prevented by the coadministration of uridine. In contrast, the immunosuppressive activity of BQR is unaffected by similar doses of uridine. PyN levels in the bone marrow, but not in the spleen, are depressed in mice treated with BQR. These observations suggest that the induction of anemia by BQR is due to depletion of intracellular PyN in hemopoietic stem cells located in the bone marrow. They also suggest that the mechanism of immunosuppression by BQR may be only marginally dependent on depletion of intracellular PyN in lymphocytes located in the periphery. We report a novel activity of BQR: inhibition of tyrosine phosphorylation, and hypothesize that the immunosuppressive activity may be due, in part, to this unsuspected ability of BQR to inhibit tyrosine phosphorylation in lymphocytes.

The non-uniform distribution of albumin in human and bovine cornea

In our previous studies, we noted a non-uniform distribution of protein tracer preferentially entering the anterior stromal lamellae of the cornea from the limbus. Given other differences reported previously between the anterior and posterior lamellae of the cornea, and the number of corneal disorders in which abnormalities are preferentially confined to either the anterior or posterior lamellae, we were prompted to examine the distribution of albumin in normal human and bovine cornea. The distribution of albumin in bovine and human cornea was studied immunohistochemically. Total soluble protein and albumin in the anterior 1/3 and posterior 2/3 of the central, middle and peripheral cornea of bovine eyes was measured biochemically. To aid in interpreting the findings, a theoretical model was developed based upon the combined effects of diffusive and convective transport. Using immunohistochemical methods, in both bovine and human eyes, intense staining of albumin was found in the anterior 1/3 of the corneal stroma. There was a gradual reduction in staining intensity from the limbus to the central cornea in the anterior corneal stroma. Less staining was found in the posterior 2/3 of corneal stroma. Additionally, a greater concentration of soluble protein and albumin was found in the anterior stroma than in the posterior stroma of the bovine eyes by biochemical analyses. The theoretical model demonstrated that this distribution of protein required a difference in excluded volume fraction between the anterior and posterior stroma and was consistent with a convective flux originating at the limbus and passing through the corneal stroma. The soluble proteins of the bovine and human cornea are preferentially concentrated in the anterior cornea and near the limbus. This distribution is likely due to differences in excluded volume fraction between the anterior and posterior stroma and a small convective flux passing through the cornea.

Projection of health benefits from ambient ozone reduction related to the use of methyl tertiary butyl ether (MTBE) in the reformulated gasoline program

To estimate potential public health benefits from ozone (O3) pollution reduction attributable to the use of methyl tertiary-butyl ether (MTBE) in gasoline, O3 dose-response estimates from the biomedical literature were combined with model estimates of O3 reduction. Modeling employed EPA MOBILE5a and Complex models to predict emission changes, industry AQIRP techniques to predict ambient O3 changes, and the National Exposure Model to predict human exposures. Human health effects considered were lung function decrements and respiratory irritant symptoms (using dose-response functions measured in laboratory and field studies), and increased death rates (using concentration-response functions inferred statistically from public-health data). Other reported health effects, such as lung inflammation, increases in asthma attacks, and hospitalizations, were not addressed because of inadequate dose-response information. Even for the health responses considered, quantitation of improvements due to MTBE use is problematical, because MTBE affects only a small percentage of existing O3 pollution, and because exposure-response relationships are not well understood for population subgroups most likely to be affected. Nevertheless, it is reasonable to conclude that even small MTBE-associated reductions in peak ambient O3 levels (1-5 ppb, according to model estimates) should yield considerable public health benefits. Tens of millions of Americans are potentially exposed to O3 in the concentration range associated with health effects. Even if only a small percentage of them are susceptible, any incremental reduction in O3 (as with MTBE use) must mitigate or prevent effects for a meaningful number of people. Better quantitative estimates of benefit must await a more detailed understanding of each link in the chain of causation.

Interendothelial junctions in normal human Schlemm's canal respond to changes in pressure

PURPOSE

To determine if changes in the structure and complexity of junctions between endothelial cells lining Schlemm's canal (SC) occur in normal human eyes with changes in perfusion pressure.

METHODS

Twelve normal human eyes were either perfusion-fixed (at 15 or 45 mm Hg) or immersion-fixed (0 mm Hg) in modified Karnovsky's fluid. 'Outflow facility was measured continually during the perfusion fixation. The intercellular junctions of the endothelial cells of SC were ultrastructurally examined in thin sections, including serial sections and freeze-fracture replicas. Morphometric data on the number of junctional strands per total length of tight junction were documented and categorized by the number of strands (one, two, or three or more). The length of endothelial cell overlap was measured on thin sections.

RESULTS

In freeze-fracture replicas, perfusion-fixed eyes demonstrated less complex junctions. At 15 mm Hg, 18.06% of the total junctional length was represented by three or more strands; at 45 mm Hg, this percentage decreased to 8.59%. In immersion-fixed eyes, 24.17% of the total junctional length was represented by three or more strands. These differences were statistically significant (P < 0.0012). In sections, the amount of endothelial cell overlap, and thus the length of paracellular pathway, was reduced in perfusion-fixed versus immersion-fixed eyes (P < 0.02). Extensive serial sectioning demonstrated that giant vacuoles were formed, either by individual endothelial cells or by two or more adjacent endothelial cells.

CONCLUSIONS

When compared with specimens fixed at zero pressure, overlap between endothelial cells of SC is reduced significantly when this cell layer is under conditions of flow similar to those encountered in vivo. The tight junctions between cells of the inner wall of SC become less complex with increasing pressure. Our data suggest that the paracellular pathway into SC in the normal eye is sensitive to modulation within a range of physiologically relevant pressures.

Control of lymphoproliferative and autoimmune disease in MRL-lpr/lpr mice by brequinar sodium: mechanisms of action

Brequinar sodium (BQR) was originally developed as an antitumor drug and subsequently as an immunosuppressant for controlling transplant rejection. It has been widely accepted that the antitumor and immunosuppressive activities of BQR are dependent on its ability to inhibit the enzymatic activity of dihydroorotate dehydrogenase, the fourth enzyme in the de novo pyrimidine synthesis pathway. Recently, we discovered that BQR has the ability to inhibit protein tyrosine phosphorylation in anti-CD3-stimulated murine T lymphocytes and to inhibit the activity of src-related protein tyrosine kinases, p56lck and p59fyn. We examined the in vivo activities of BQR in MRL-lpr/lpr mice. We report that the dose of BQR (10 mg/kg/day) that induced anemia, controlled lymphadenopathy and inhibited autoantibody production, also selectively reduced the pyrimidine nucleotide levels in the bone marrow and in the lymph nodes. Coadministration of uridine (1000 mg/kg/day) with BQR completely normalized pyrimidine nucleotide levels in the bone marrow and lymph nodes, and prevented BQR-induced anemia. However, coadministration of uridine with BQR only partially reversed the anti-proliferative effects of BQR, and did not antagonize the inhibitory effect of BQR on autoantibody production. Finally, we report that BQR markedly reduced protein tyrosine phosphorylation in lymph nodes of MRL-lpr/lpr mice. These results collectively suggest that the control of lymphadenopathy and autoantibody production in MRL-lpr/lpr mice by BQR is only partially dependent on inhibition of pyrimidine nucleotide synthesis, and suggest a critical role for in vivo inhibition of protein tyrosine phosphorylation.

Xenopus Cdc6 confers sperm binding competence to oocytes without inducing their maturation

Amphibian eggs normally require meiotic maturation to be competent for fertilization. A necessary prerequisite for this event is sperm binding, and we show that under normal physiological conditions this property is acquired at, but not before, meiotic maturation. Immature oocytes do not bind sperm, but injection of total egg poly(A)+ mRNA into immature oocytes confers sperm binding in the absence of meiotic maturation. Using an expression cloning approach we have isolated a single cDNA from egg poly(A)+ mRNA that can induce sperm binding in immature oocytes. The cDNA was found to encode Xenopus Cdc6, a protein that previously has been shown to function in initiation of DNA replication and cell cycle control. This unanticipated finding provides evidence of a link between a regulator of the cell cycle and alterations in cell surface properties that affect gamete binding.

Intraocular pressure and outflow facility are unchanged following acute and chronic intracameral chondroitinase ABC and hyaluronidase in monkeys

We determined the effect of chronic and acute loss of glycosaminoglycans from the aqueous outflow pathway on intraocular pressure (IOP) and outflow facility in the subhuman primate eye. For the study of the chronic effects of the GAGases, cynomolgus monkeys received intracameral injections of hyaluronidase (Streptomyces, 5 or 50 units, n=2) or chondroitinase ABC (0.05 or 0.25 units, n=2) biweekly for 8 months (4 months for each dose). IOP was measured at 3, 7, 10 and 14 days after each injection. Outflow facility (2-level constant pressure) was determined at 2, 4, 6, and 8 months. Monkeys were killed 6 days after the last injection. The changes in the distribution of hyaluronic acid and sulfated proteoglycans in the outflow pathway were examined using substrate-specific histochemical techniques. The acute effects of these enzymes on outflow facilities (30 min or 2 hr after enzyme) were determined in another group of animals (n=4 for each time enzyme-1). IOP and outflow facility were unchanged compared to controls (heat inactivated enzyme) at any time in the chronically or acutely treated monkeys. Hyaluronic acid staining was absent in the outflow pathways of eyes treated chronically with hyaluronidase compared with control eyes, while collagen-associated sulfated proteoglycans were decreased but not completely removed by the chronic chondroitinase ABC treatment. Chronic loss of these glycosaminoglycans from the trabecular meshwork does not appear to contribute to the IOP elevation and decrease in outflow facility that accompanies open-angle glaucoma. Most importantly, no increase in outflow facility was found with acute hyaluronidase or chondroitinase treatment.

Comparison of ion exchange and cw CO(2) laser treatment of Nd-doped phosphate laser glass

We investigate the relation of ion-exchange treatment and laser conditioning of a glass surface. The surface of Nd-doped phosphate laser glass was preirradiated with a cw CO(2) laser and strengthened by the ion-exchange treatment. It is shown that residual compressive stress occurs on the surface as peak-to-valley roughness and the appearance of microcracks decreases. Damage threshold of the glass surface increases by a factor of 1.7-3. The mechanism of laser conditioning is consistent with that of the ion-exchange treatment.

Xenopus laevis sperm-egg adhesion is regulated by modifications in the sperm receptor and the egg vitelline envelope

The biochemical and ultrastructural changes in the envelope of the Xenopus laevis egg that occur during oviposition and fertilization have been thoroughly studied (Hedrick, J. L., and Nishihara, D. M., Methods Cell Biol. 36, 231-247, 1991; Larabell, C. A., and Chandler, D. E., J. Electron Microsc. Tech. 17, 294-318, 1991). However, the biological significance of these changes with respect to gamete interaction has been unclear. In the current study, it was found that changes in the envelope are directly responsible for regulating sperm-egg adhesion, an initial step of fertilization. As a result of these transformations, sperm bind only to unfertilized oviposited eggs, not to oocytes or coelomic eggs. In addition, they do not bind to fertilized eggs. The molecular and cellular basis of the regulation of the sperm binding process was investigated in the context of our recent findings that two structurally related envelope glycoproteins, gp69/64, serve as sperm receptors during fertilization (Tian, J.-D., Gong, H., Thomsen, G. H., and Lennarz, W. J., J. Cell Biol. 136, 1099-1108, 1997). Although the purified gp69/64 glycoproteins isolated from the oocyte or coelomic egg envelopes exhibited sperm binding activity, when these proteins are part of the intact oocyte or coelomic egg envelopes, they are not accessible to either anti-gp69/64 antibodies or to sperm. During the conversion from the coelomic to the vitelline envelope, the gp69/64 sperm receptors become exposed on the surface, an event that correlates with proteolytic cleavage of gp43 and accompanying ultrastructural alterations in the envelope. Conversely, after fertilization, when the vitelline envelope of the egg is converted to the fertilization envelope of the zygote, limited proteolytic cleavage of the sperm receptor results in loss of sperm binding activity. In addition, formation of a fertilization layer on top of the structurally altered VE adds another physical block to sperm binding. These results provide new insights into structure-function relationships between envelope components of the anuran egg, and provide further evidence supporting the key role of gp69/64 as sperm receptors during X. laevis fertilization.

In vivo mechanism by which leflunomide controls lymphoproliferative and autoimmune disease in MRL/MpJ-lpr/lpr mice

Two activities have been identified for the immunosuppressive metabolite of leflunomide, A77 1726: inhibition of dihydroorotate dehydrogenase (DHO-DHase), an enzyme involved in the biosynthesis of pyrimidine nucleotides (PyN); and inhibition of protein tyrosine kinases. The in vitro potency of A77 1726 as a DHO-DHase inhibitor is reported to be 10- to 500-fold greater than as a tyrosine kinase inhibitor. These observations suggested that the immunosuppressive efficacy of leflunomide in vivo is related to inhibition of DHO-DHase. However, observations that patients with disorders in the PyN synthetic pathway are not overtly immunodeficient militate against this hypothesis. We investigated the effects of leflunomide in vivo and report that amelioration of lymphoproliferative and autoimmune diseases in MRL/MpJ-lpr/lpr (lpr/lpr) mice by leflunomide is not accompanied by reduced PyN concentrations in lymph node cells. Our hypothesis that lymphocytes could salvage serum uridine to counter the effects of reduced PyN synthesis in vivo was supported by in vitro studies. Finally, we observed that amelioration of disease correlated with a reduction of tyrosine phosphorylated proteins in lymph node cells of lpr/lpr mice. These observations suggest that the primary mechanism by which leflunomide prevents autoimmune and lymphoproliferative diseases in lpr/lpr mice is not depletion of PyN, but correlates with reduced tyrosine phosphorylation concentrations in lymph node cells.

In vivo mechanism by which leflunomide controls lymphoproliferative and autoimmune disease in MRL/MpJ-lpr/lpr mice

Two activities have been identified for the immunosuppressive metabolite of leflunomide, A77 1726: inhibition of dihydroorotate dehydrogenase (DHO-DHase), an enzyme involved in the biosynthesis of pyrimidine nucleotides (PyN); and inhibition of protein tyrosine kinases. The in vitro potency of A77 1726 as a DHO-DHase inhibitor is reported to be 10- to 500-fold greater than as a tyrosine kinase inhibitor. These observations suggested that the immunosuppressive efficacy of leflunomide in vivo is related to inhibition of DHO-DHase. However, observations that patients with disorders in the PyN synthetic pathway are not overtly immunodeficient militate against this hypothesis. We investigated the effects of leflunomide in vivo and report that amelioration of lymphoproliferative and autoimmune diseases in MRL/MpJ-lpr/lpr (lpr/lpr) mice by leflunomide is not accompanied by reduced PyN concentrations in lymph node cells. Our hypothesis that lymphocytes could salvage serum uridine to counter the effects of reduced PyN synthesis in vivo was supported by in vitro studies. Finally, we observed that amelioration of disease correlated with a reduction of tyrosine phosphorylated proteins in lymph node cells of lpr/lpr mice. These observations suggest that the primary mechanism by which leflunomide prevents autoimmune and lymphoproliferative diseases in lpr/lpr mice is not depletion of PyN, but correlates with reduced tyrosine phosphorylation concentrations in lymph node cells.

The immunosuppressive metabolite of leflunomide, A77 1726, affects murine T cells through two biochemical mechanisms

The immunosuppressive metabolite of leflunomide, A77 1726, inhibits the enzymatic activity of protein tyrosine kinases and of dihydro-orotic acid dehydrogenase, an enzyme involved in pyrimidine biosynthesis. Here murine CTLL cell lines were studied to determine which of the biochemical targets of A77 1726 was responsible for the observed inhibition of proliferation and cytotoxic activity. At low concentrations of A77 1726, pyrimidine biosynthesis is the target, since inhibition of proliferation correlates with a reduction in pyrimidine NTP levels and is reversed by uridine. At higher concentrations of A77 1726, uridine no longer reverses the inhibition of proliferation even though pyrimidine NTP levels are restored. This second mechanism for inhibiting proliferation is probably inhibition of protein tyrosine kinases, since these higher concentrations of A77 1726 inhibit IL-2-induced tyrosine phosphorylation of Jak1 and Jak3, the protein tyrosine kinases initiating signaling by the IL-2R. Tyrosine phosphorylation of the beta-chain of the IL-2R, which is required for IL-2-driven proliferation, is also inhibited by A77 1726. Cytotoxicity of a CTLL line that overexpresses the Lck protein tyrosine kinase is inhibited by A77 1726; this inhibition is not affected by uridine, but does correlate with inhibition of an Lck in vitro kinase reaction. These studies establish that inhibition of pyrimidine biosynthesis and that of protein tyrosine kinase both contribute to the effects of A77 1726 on CTLL cell lines.

The immunosuppressive metabolite of leflunomide, A77 1726, affects murine T cells through two biochemical mechanisms

The immunosuppressive metabolite of leflunomide, A77 1726, inhibits the enzymatic activity of protein tyrosine kinases and of dihydro-orotic acid dehydrogenase, an enzyme involved in pyrimidine biosynthesis. Here murine CTLL cell lines were studied to determine which of the biochemical targets of A77 1726 was responsible for the observed inhibition of proliferation and cytotoxic activity. At low concentrations of A77 1726, pyrimidine biosynthesis is the target, since inhibition of proliferation correlates with a reduction in pyrimidine NTP levels and is reversed by uridine. At higher concentrations of A77 1726, uridine no longer reverses the inhibition of proliferation even though pyrimidine NTP levels are restored. This second mechanism for inhibiting proliferation is probably inhibition of protein tyrosine kinases, since these higher concentrations of A77 1726 inhibit IL-2-induced tyrosine phosphorylation of Jak1 and Jak3, the protein tyrosine kinases initiating signaling by the IL-2R. Tyrosine phosphorylation of the beta-chain of the IL-2R, which is required for IL-2-driven proliferation, is also inhibited by A77 1726. Cytotoxicity of a CTLL line that overexpresses the Lck protein tyrosine kinase is inhibited by A77 1726; this inhibition is not affected by uridine, but does correlate with inhibition of an Lck in vitro kinase reaction. These studies establish that inhibition of pyrimidine biosynthesis and that of protein tyrosine kinase both contribute to the effects of A77 1726 on CTLL cell lines.

[Measurement and analysis of tumor tissue autofluorescence spectra]

Measurement results of laser induced autofluorescence spectra of tumor tissue from little rat are given in this paper it is compared with normal tissue of the same body After analyzing the origin of tumor tissue autofluorescence and the difference with normal tissue spectra, it is concluded that autofluorescence spectra of tissue may reflect the features of tumor tissue and be utilized to diagnose the tumor.

Chamber exposures of children to mixed ozone, sulfur dioxide, and sulfuric acid

To help assess acute health effects of summer air pollution in the eastern United States, we simulated ambient "acid summer haze" as closely as was practical in a laboratory chamber. We exposed young volunteers who were thought to be sensitive to this pollutant mixture on the basis of previous epidemiologic evidence. Specifically, we exposed 41 subjects aged 9-12 y to mixed ozone (0.10 ppm), sulfur dioxide (0.10 ppm), and 0.6-microm sulfuric acid aerosol (100 +/- 40 microg/m3, mean +/- standard deviation) for 4 h, during which there was intermittent exercise. Fifteen subjects were healthy, and 26 had allergy or mild asthma. The entire group responded nonsignificantly (p > .05) to pollution exposure (relative to clean air), as determined by spirometry, symptoms, and overall discomfort level during exercise. Subjects with allergy/asthma showed a positive association (p = .01) between symptoms and acid dose; in healthy subjects, that association was negative (p = .08). In these chamber-exposure studies, we noted less of an effect than was reported in previous epidemiologic studies of children exposed to ambient "acid summer haze."

The role of soluble proteins in generating aqueous outflow resistance in the bovine and human eye

Previous research has shown that wash-out in bovine and primate eyes can be greatly reduced by perfusing with buffer containing 5-15% serum. It was suggested that protein diffusion from the iris root might raise the in vivo protein concentration in the trabecular meshwork to a level much higher than in the anterior chamber. In this study, we investigated the protein concentration in effluent from the outflow pathways in bovine and human eyes, its possible relationship to wash-out, and whether the reduction of wash-out was caused by a bulk protein effect. Bovine and human eyes were placed under silicone oil and perfused with buffer. Outflow facility was continuously determined while effluent was periodically collected from the surface of the eye, and the soluble protein concentration in the effluent was determined. Separate studies were conducted perfusing either albumin or gamma-globulin through bovine eyes. Theoretical models were developed to study the transport of protein into the perfusion fluid. In the bovine eyes, the initial protein concentration in the collected effluent was approximately 1% that of serum, much lower than the 10-15% buffer in serum required to prevent wash-out. Furthermore, the rate of change of outflow facility showed a different dependence on perfused volume than did the protein concentration. Human eyes showed a much higher level of protein in the perfusate, that decayed over a much longer time period. A statistically significant correlation existed between outflow resistance and soluble protein concentration in both bovine and human eyes. However, modelling studies suggested that this correlation might be due to flow resistance setting the flowrate which then determines the protein concentration of the effluent. Separate experiments indicated that the decreased rate of wash-out caused by perfusion of 10-15% serum in buffer was not due to either albumin or gamma-globulin alone. These results suggest that the reduction of wash-out observed in previous studies when serum proteins were perfused through bovine and monkey eyes was not due to the general level of serum proteins but may instead be due to interactions of a particular protein(s).

Hyaluronic acid in the normal and glaucomatous optic nerve

Eighteen normal human eye-bank eyes (age: 18-81 years), five fetal eyes (16-24 weeks), 11 primary open-angle glaucoma (POAG) eyes (age: 76-89 years), and two Schnabel's cavernous optic atrophy eyes were examined using a biotinylated-hyaluronan binding protein to study the changes in the distribution of hyaluronic acid (HA) in the fetal, adult and glaucomatous optic nerve head. The vitreous body served as a positive control. Sections treated with Streptomyces hyaluronidase were used to confirm specificity. Monoclonal antibodies to myelin basic protein (MBP) and glial fibrillary acidic protein (GFAP) were used as additional controls. In fetal optic nerve, HA was localized in blood vessels, peripapillary sclera and the pial septae in the retrolaminar nerve. No staining was associated with axons. Staining for MBP was negative. In adults, HA was found surrounding the myelin sheaths in the retrolaminar nerve; staining decreased with age. In contrast, HA staining in myelinated peripheral nerves (e.g. ciliaries) remained unchanged with age. HA also was localized to the adventitia of arteries and veins throughout the posterior segment. Compared to age-matched normal eyes, HA staining was virtually absent around myelin sheaths of the retrolaminar nerve in POAG eyes. Similar changes were not found in other HA positive structures. In Schnabel's cavernous optic atrophy. HA was present in increased amount in the atrophic area, but virtually absent in the remaining retrolaminar nerve. HA staining was invariably positive in vitreous, and Streptomyces hyaluronidase treated sections were negative. In adults, staining of MBP was associated with the myelin sheath in the retrolaminar nerve. In contrast to HA, staining of MBP was unchanged with age and in POAG. In Schnabel's atrophy, MBP staining disappeared only in the atrophic area. HA in the retrolaminar optic nerve appears to be associate with the space-filling matrix between myelin sheaths. HA is not present in the axon bundles prior to myelination of the optic nerve. HA in the retrolaminar optic nerve appears to decrease with age and is further reduced in POAG; however, corresponding changes are not found in MBP or in peripheral nerves. Perhaps, decreased amounts of HA is related to a higher susceptibility to elevated intraocular pressure or to optic nerve atrophy. In Schnabel's cavernous optic atrophy, HA is present in increased amount only in the atrophic area while MBP is markedly decreased, suggesting in situ production of HA in areas of optic nerve atrophy.