Influence of rearing system on growth performance, carcass traits, and meat quality of Yangzhou geese

An experiment was conducted using a total of 540 one-day-old Yangzhou geese to study the effect of rearing system on growth performance, carcass traits, and meat quality of male and female Yangzhou geese. The birds were divided into homogeneous groups according to initial BW and sex. The male and female geese were raised in separate pens under 5 different treatments, with 3 replicate pens of 18 male or 18 female geese per pen for each treatment. This experiment included 2 stages, with geese at 1 to 28 d of age (the first stage) and 29 to 70 d of age (the second stage). The 5 different treatments were 1) system A (geese raised on a wire floor), 2) system B (geese raised on the floor), 3) system C (geese raised on the floor and transferred to to a wire floor), 4) system D (geese raised on a wire floor and transferred to the floor), and 5) system E (geese raised on the floor and transferred to a free range). Results showed that feed conversion rate, BW, and BW gain were significantly affected by rearing system and sex (P < 0.05). For carcass yield, results suggested that eviscerated carcass yield and heart yield were affected by rearing system (P < 0.05) but not by sex (P > 0.05). Differences between sexes, but not rearing systems, were observed for only breast yield, thigh yield, and liver yield (P < 0.05). Rearing system and sex had a remarkable effect (P < 0.05) on subcutaneous fat thickness, abdominal fat yield, and gizzard yield. The nutrient composition (water, protein, and fat), water-holding capacity, shear force, and pH of the pectoralis major muscle were not affected (P > 0.05) by the rearing system, and only water, protein, and pH of the meat were affected by sex (P < 0.05). This study indicates that rearing system A, in which Yangzhou geese were raised on a wire floor, improved growth performance but had little effect on meat quality, implying that the use of rearing system A, using a wire floor, might be feasible and effective for Yangzhou geese.

The buccofacial wall of maxillary sinus: an anatomical consideration for sinus augmentation

PURPOSE

This study aimed to quantify the thickness of the buccofacial wall of the maxillary sinus where sinus augmentations are often performed.

MATERIALS AND METHODS

Fourteen sites located 15 and 20 mm superior to the anatomical cervical line (named as groups H15 and H20, respectively) and along the long axes of the mid and the interproximal of two premolars and two molars were measured from 74 Korean hemiface cadavers.

RESULTS

The buccofacial wall of the maxillary sinus was thinnest at the area between the maxillary second premolar and first molar in groups H15 and H20. The lowest mean thickness was 1.2 mm in both groups. The walls were thicker in males than in females, with statistically significant gender differences found at four and two sites on the anterior horizontal reference in groups H15 and H20, respectively. However, the thickness did not differ significantly with age or laterality. Incomplete septa were found in seven of the 74 specimens, and they were present in the area between the first and second molars in six (86%) of these cases.

CONCLUSIONS

These observations indicate that anatomical characteristics of the buccofacial wall thickness of the maxillary sinus need to be considered when performing a window opening procedure for sinus augmentation.

Effects of payoff functions and preference distributions in an adaptive population

Adaptive populations such as those in financial markets and distributed control can be modeled by the Minority Game. We consider how their dynamics depends on the agents' initial preferences of strategies, when the agents use linear or quadratic payoff functions to evaluate their strategies. We find that the fluctuations of the population making certain decisions (the volatility) depends on the diversity of the distribution of the initial preferences of strategies. When the diversity decreases, more agents tend to adapt their strategies together. In systems with linear payoffs, this results in dynamical transitions from vanishing volatility to a nonvanishing one. For low signal dimensions, the dynamical transitions for the different signals do not take place at the same critical diversity. Rather, a cascade of dynamical transitions takes place when the diversity is reduced. In contrast, no phase transitions are found in systems with the quadratic payoffs. Instead, a basin boundary of attraction separates two groups of samples in the space of the agents' decisions. Initial states inside this boundary converge to small volatility, while those outside diverge to a large one. Furthermore, when the preference distribution becomes more polarized, the dynamics becomes more erratic. All the above results are supported by good agreement between simulations and theory.

Successful application of tissue-engineered skin to refractory ulcers

In this study, the effectiveness of a tissue-engineered skin (Activskin; Aierfu, Xi'an, China) was evaluated for the treatment of various refractory ulcers. These ulcers were treated with Activskin after debridement and irrigation with saline. A second application of Activskin was essential if the first application failed to persist on the wounds. Clinical efficacy and safety were assessed at regular clinic visits during 6 months of follow-up. All 11 treated patients improved with Activskin. The ulcers healed by inward migration from the wound edge. The average healing time was 27.8 days. No recurrent ulceration or other adverse events were observed during follow-up. These results provide preliminary evidence that Activskin is safe and effective in the management of refractory ulcers.

Nitrogen requirement for maintenance in Yangzhou goslings

1. Experiments were conducted to determine the nitrogen (N) requirement for maintenance (N(m)) in Yangzhou goslings. 2. At 56 d old, 18 birds were divided into three equal groups and fed on diets with equal metabolisable energy (ME) and different contents of crude protein (CP; low, medium and high) in an N balance test. N(m) was estimated from the relationship between N output (N(E)) and N intake (N(I)). Following the above N balance test, 16 goslings at the same age were used in a N balance test with an N-free diet. The birds were divided into 4 equal groups and offered an N-free diet at intakes of 90, 70, 50 and 0 g per d, respectively. 3. The estimated N(m) was 240 mg/kg BW(0.75) per d in the N balance test. The result from the N-free diet trial gave a value of 244 mg/kg BW(0.75) per d, confirming the result of the N balance test. The lower intake of N-free diet resulted in more N(E), suggesting that protein catabolism may occur in the body of birds to meet N(m) when dietary N(I) was very low. 4. It was concluded that the N(m) of Yangzhou goslings was about 240 mg/kg BW(0.75).

Introduction of a disulfide bridge enhances the thermostability of a Streptomyces olivaceoviridis xylanase mutant

Substitution of the N-terminus of Streptomyces olivaceoviridis xylanase XYNB to generate mutant TB has been previously shown to increase the thermostability of the enzyme. To further improve the stability of this mutant, we introduced a disulfide bridge (C109-C153) into the TB mutant, generating TS. To assess the effect of the disulfide bridge in the wild-type enzyme, the S109C-N153C mutation was also introduced into XYNB, resulting in XS. The mutants were expressed in Pichia pastoris, the recombinant enzymes were purified, and the effect of temperature and pH on enzymatic activity was characterized. Introduction of the disulfide bridge (C109-C153) into XYNB (XS variant) and TB (TS variant) increased the thermostability up to 2.8-fold and 12.4-fold, respectively, relative to XYNB, after incubation at 70 degrees C, pH 6.0, for 20 min. In addition, a synergistic effect of the disulfide bridge and the N-terminus replacement was observed, which extended the half-life of XYNB from 3 to 150 min. Moreover, XS and TS displayed better resistance to acidic conditions compared with the respective enzymes that did not contain a disulfide bridge.

Current status of water reuse systems in Korea

In Korea, the current water resources will fall short by 2.6 billion tons to meet the 38 billion ton water demand in the year 2020. To overcome the future water shortage, it is desirable to minimize water consumption and to reuse treated wastewater. There are a total of 99 on-site water-recycling systems in the country. The potential capacity of the 99 systems is 429 thousands tons/day, which is 3.6% of the total service water. Compared to other industrialized countries, the number of the water recycling systems in Korea is extremely small. This is mainly due to the following reasons. First, in Korea, any building with more than 60,000 m2 of total floor space is required to install a water reuse system by law. However, only less than 0.5% of the total buildings have more than 10,000 m2. Therefore, the regulation is ineffective and merely nominal. Second, service water is supplied at low charge (0.20 US-dollar/m3 water). The inexpensive service water often discourages people to recycle treated wastewater. Third, people still think recycled water is not clean enough and can cause diseases. Therefore, they should be informed that a well-maintained recycling system does not fail to produce water with high quality.

Effect of exposure to diesel exhaust particles on the susceptibility of the lung to infection

There are at least three mechanisms by which alveolar macrophages play a critical role in protecting the lung from bacterial or viral infections: production of inflammatory cytokines that recruit and activate lung phagocytes, production of antimicrobial reactive oxidant species, and production of interferon (an antiviral agent). In this article we summarize data concerning the effect of exposure to diesel exhaust particles on these alveolar macrophage functions and the role of adsorbed organic chemicals compared to the carbonaceous core in the toxicity of diesel particles. In vitro exposure of rat alveolar macrophages to diesel exhaust particles decreased the ability of lipopolysaccharide (LPS), a bacterial product] to stimulate the production of inflammatory cytokines interleukin-1 (IL-1) and tumor necrosis factor-alpha (TNF-alpha). Methanol extract exhibited this potential but methanol-washed diesel particles did not. Exposure of rats to diesel exhaust particles by intratracheal instillation also decreased LPS-induced TNF-alpha and IL-1 production from alveolar macrophages. In contrast, carbon black did not exhibit this inhibitory effect. Exposure of rats to diesel exhaust particles by inhalation decreased the ability of alveolar macrophages to produce antimicrobial reactive oxidant species in response to zymosan (a fungal component). In contrast, exposure to coal dust increased zymosan-stimulated oxidant production. In vivo exposure to diesel exhaust particles but not to carbon black decreased the ability of the lungs to clear bacteria. Inhalation exposure of mice to diesel exhaust particles but not to coal dust depressed the ability of the lung to produce the antiviral agent interferon and increased viral multiplication in the lung. These results support the hypothesis that exposure to diesel exhaust particles increases the susceptibility of the lung to infection by depressing the antimicrobial potential of alveolar macrophages. This inhibitory effect appears to be due to adsorbed organic chemicals rather than the carbonaceous core of the diesel particles.

Effect of age on respiratory defense mechanisms: pulmonary bacterial clearance in Fischer 344 rats after intratracheal instillation of Listeria monocytogenes

STUDY OBJECTIVES

To examine the lung defense mechanisms of both young and aged rats before and after pulmonary challenge with a bacterial pathogen.

DESIGN

Male Fischer 344 rats, either 2.5 months or 20 months of age, were intratracheally inoculated with 5 x 10(3), 5 x 10(4), or 5 x 10(5) Listeria monocytogenes, and the effects on mortality, lung inflammation, pulmonary bacterial clearance, alveolar macrophage (AM) function, and T-lymphocyte characterization were determined.

MEASUREMENTS AND RESULTS

In noninfected control animals, the older rats had lower numbers of AMs on lavage and a lower percentage of total T, CD4+, and CD8+ cells. No difference was observed between noninfected young and old rats in AM function, assessing both chemiluminescence and nitric oxide (NO) production. After bacterial challenge, aged rats exhibited an increase in mortality, pulmonary infection, and edema, and lung lesions, which were more extensive than those observed in the younger rats. Interestingly, AM chemiluminescence was enhanced, while AM NO, a highly important antibacterial defense product, was abrogated in the aged rats as compared to the young rats.

CONCLUSIONS

This study demonstrated that advanced age is associated with alterations in lung defense mechanisms and increased susceptibility to pulmonary bacterial infection marked by elevated mortality, slowed pulmonary bacterial clearance, and altered AM function, specifically a decrease in NO production. These observations are indicative of reduced pulmonary defense function in an older population of rats.

Effect of silica inhalation on the pulmonary clearance of a bacterial pathogen in Fischer 344 rats

Silica inhalation predisposes workers to bacterial infection and impairments in pulmonary defense function. In this study, we evaluated the effect of pre-exposure to silica on lung defense mechanisms by use of a rat pulmonary Listeria monocytogenes infection model. Male Fischer 344 rats were exposed by inhalation to filtered air or silica (15 mg/m3 x 6 h/day x 5 days/wk). After 21 or 59 days of silica exposure, the rats were inoculated intratracheally with 5 x 10(3) L. monocytogenes. At 0 (noninfected controls), 3, and 7 days after infection, the left lungs were removed, homogenized, and the number of viable L. monocytogenes was counted after an overnight culture at 37 degrees C. Bronchoalveolar lavage (BAL) was performed on the right lungs. Alveolar macrophages (AM) were collected, and the AM production of chemiluminescence (CL), an index of reactive oxygen species generation, was measured. The number of lavagable neutrophils (PMNs) and acellular BAL lactate dehydrogenase (LDH) activity were determined as indices of inflammation and injury, respectively. Pre-exposure to silica for 59 days caused substantial increases in PMN number and LDH activity compared with the air controls, whereas silica inhalation for both 21 and 59 days significantly enhanced the pulmonary clearance of L. monocytogenes compared with air controls. Dramatic elevations were also observed in zymosan- and phorbol myristate acetate (PMA)-stimulated CL production by lung phagocytes recovered from rats pre-exposed to silica for 59 days. These results demonstrate that short-term exposure to inhaled silica particles activates lung phagocytes, as evidenced by increases in reactive oxygen species. This up-regulation in the production of antimicrobial oxidants is likely responsible for the enhancement in pulmonary clearance of L. monocytogenes observed with short-term silica inhalation.

A mathematical model for malaria transmission relating global warming and local socioeconomic conditions

OBJECTIVE

Sensitivity analysis was applied to a mathematical model describing malaria transmission relating global warming and local socioeconomic conditions.

METHODS

A previous compartment model was proposed to describe the overall transmission of malaria. This model was built up on several parameters and the prevalence of malaria in a community was characterized by the values assigned to them. To assess the control efforts, the model parameters can vary on broad intervals.

RESULTS

By performing the sensitivity analysis on equilibrium points, which represent the level of malaria infection in a community, the different possible scenarios are obtained when the parameters are changed.

CONCLUSIONS

Depending on malaria risk, the efforts to control its transmission can be guided by a subset of parameters used in the mathematical model.

Diesel exhaust particles suppress macrophage function and slow the pulmonary clearance of Listeria monocytogenes in rats

In this study, we tested the hypothesis that exposure to diesel exhaust particles (DEP) may increase susceptibility of the host to pulmonary infection. Male Sprague-Dawley rats received a single dose of DEP (5 mg/kg), carbon black (CB, 5 mg/kg), or saline intratracheally. Three days later, the rats were inoculated intratracheally with approximately 5,000 Listeria monocytogenes and sacrificed at 3, 5, and 7 days postinfection, and we determined the number of viable Listeria in the left lobe of lungs. The remaining lungs underwent bronchoalveolar lavage (BAL) and the retrieved BAL cells were identified and counted. Luminol-dependent chemiluminescence, a measure of reactive oxygen species (ROS) formation, generated by BAL cells was monitored and the levels of nitric oxide and tumor necrosis factor (TNF)-[alpha] produced by macrophages in culture were determined. At 7 days postinfection, we excised the lung-draining lymph nodes and phenotyped the lymphocyte subpopulations. Exposure of rats to DEP, but not to CB, decreased the clearance of Listeria from the lungs. Listeria-induced generation of luminol-dependent chemiluminescence by pulmonary phagocytes decreased by exposure to DEP but not CB. Similarly, Listeria-induced production of NO by alveolar macrophages was negated at 3, 5, and 7 days after inoculation in DEP-exposed rats. In contrast, CB exposure had no effect on Listeria-induced NO production at 3 days after infection and had a substantially smaller effect than DEP at later days. Exposure to DEP or CB resulted in enlarged lung-draining lymph nodes and increased the number and percentage of CD4(+) and CD8(+) T cells. These results showed that exposure to DEP decreased the ability of macrophages to produce antimicrobial oxidants in response to Listeria, which may play a role in the increased susceptibility of rats to pulmonary infection. This DEP-induced suppression is caused partially by chemicals adsorbed onto the carbon core of DEP, because impaired macrophage function and decreased Listeria clearance were not observed following exposure to CB.

Diesel exhaust particles suppress macrophage function and slow the pulmonary clearance of Listeria monocytogenes in rats

In this study, we tested the hypothesis that exposure to diesel exhaust particles (DEP) may increase susceptibility of the host to pulmonary infection. Male Sprague-Dawley rats received a single dose of DEP (5 mg/kg), carbon black (CB, 5 mg/kg), or saline intratracheally. Three days later, the rats were inoculated intratracheally with approximately 5,000 Listeria monocytogenes and sacrificed at 3, 5, and 7 days postinfection, and we determined the number of viable Listeria in the left lobe of lungs. The remaining lungs underwent bronchoalveolar lavage (BAL) and the retrieved BAL cells were identified and counted. Luminol-dependent chemiluminescence, a measure of reactive oxygen species (ROS) formation, generated by BAL cells was monitored and the levels of nitric oxide and tumor necrosis factor (TNF)-[alpha] produced by macrophages in culture were determined. At 7 days postinfection, we excised the lung-draining lymph nodes and phenotyped the lymphocyte subpopulations. Exposure of rats to DEP, but not to CB, decreased the clearance of Listeria from the lungs. Listeria-induced generation of luminol-dependent chemiluminescence by pulmonary phagocytes decreased by exposure to DEP but not CB. Similarly, Listeria-induced production of NO by alveolar macrophages was negated at 3, 5, and 7 days after inoculation in DEP-exposed rats. In contrast, CB exposure had no effect on Listeria-induced NO production at 3 days after infection and had a substantially smaller effect than DEP at later days. Exposure to DEP or CB resulted in enlarged lung-draining lymph nodes and increased the number and percentage of CD4(+) and CD8(+) T cells. These results showed that exposure to DEP decreased the ability of macrophages to produce antimicrobial oxidants in response to Listeria, which may play a role in the increased susceptibility of rats to pulmonary infection. This DEP-induced suppression is caused partially by chemicals adsorbed onto the carbon core of DEP, because impaired macrophage function and decreased Listeria clearance were not observed following exposure to CB.

[Effect of improved topical agents on healing time of deep second-degree burn wound]

OBJECTIVE

With the recognization of the mechanism of wound healing, some topical agents are created and applied in trauma to improve the healing rate of wounds. The main purpose of this study is to investigate the effect of some topical agents on the healing rate of deep second-degree burn wounds.

METHODS

One thousand five hundred and sixty-three patients with deep second-degree burn wounds(total burn surface area < or = 10%) were involved in this study from January 1982 to December 1999. According to the application time of different treating measures including supplement of Zn, application of growth factors and collagenase, the patients were divided into 3 groups, wound healing rates were compared.

RESULTS

Before 1991, none of special topical agents were used, and the healing time of deep second-degree burn wounds was(23.8 +/- 3.5) days. From 1991 to 1996, with the topical application of SD-Ag-Zn, which can provide Zn for cells taking part in wound healing, the healing time of deep second-degree burn wounds was (20.6 +/- 3.2) days, earlier than no special topical agents (P < 0.05). From 1997 to 1999, growth factors such as basic fibroblast growth factor(bFGF) and epithelial growth factor (EGF) and collagenases were applied in wound treatment combining with SD-Ag-Zn, wound healing time was (16.2 +/- 2.8) days, earlier than no special topical agents (P < 0.01) and simple SD-Ag-Zn application (P < 0.05).

CONCLUSION

It indicates that the improvement of topical agents can accelerate wound healing speed.

[STR polymorphisms in five Chinese ethnic groups(2)]

Population genetic studies were performed in Chinese Han, Hui, Mongolian, Tibetan and Uygur. Allele frequency distributions were analyzed for ten loci, i.e., D3S1358, VWA, CSF1PO, FGA, THO1, TPOX, D5S818, D13S317 and D7S820 by GeneScan. The results showed that there were 60 STR alleles and 149 genotypes in Han; 63 STR alleles and 144 genotypes in Hui; 69 STR alleles and 173 genotypes in Mongolian; 77 STR alleles and 168 genotypes in Tibetan; 70 STR alleles and 148 genotypes in Uygur. Significant differences were identified among ethnic groups (African-American, US-Caucasian and Chinese-Oriental), but similarity was found among the five Chinese populations, and immunogenomics and pharmacogenomics studied in this report. These findings indicated that the nine STR loci and amelogenin locus were very useful for individual identification in forensic science.

[Genescan for STR analysis and genetic distribution in a population sample from Han, China]

Genetic distributions for nine STR loci and Amelogenin locus were determined in a Chinese Han population based on DNA sequencing. The databanks in Chinese Population were generated by using Genescan, genotype and genetic distribution analysis. Allele frequency distribution was determined for 10 loci, such as D3S1358, VWA, FGA, Amelogenin, THO1, TPOX, CSF1PO, D5S818, D13S317 and D7S820. The results show significant differences between ethnic groups (African-American, US-Caucasian and Chinese Han) in the pattern of distribution as well as in the related frequency of the most common alleles of their STR loci. The probabilities of identity values for the population described in this section are 2.79 x 10(-10) (U.S-Caucasian), 1.23 x 10(-10) (African-American) and 0.5 x 10(-10) (Chinese Han). The results show the probability of Paternity Exclusion (PPE) values of 0.9998 (Chinese Han), 0.9996 (African-American) and 0.9994 (U.S-Caucasian). These results suggested that the nine STR loci and the Amelogenin locus are very useful for human identification, such as analyzing forensis casework, establishing DNA databanks, processing paternity test, evaluation linkage genetics, studying gene natural resources and monitoring bone marrow transplants.

[Population genetics of Chinese surnames. II. Inheritance stability of surnames and regional consanguinity of population]

This paper analyzes and compares the distributional curves and isonymy of surnames and the consanguinity of regional population in the Song and Ming dynasties and the 2 present. The distribution of surnames in the three periods reveals two significant phenomena: (1) The historical inheritance of Chinese surnames is continuous and stable. This explains why the consanguineous culture relics represented by surnames and the evolution of life substances especially Y chromosome has basically the same pattern. (2) Two types of surnames, common and rare, can be identified in China. The 100 common surnames, less than 5% of the total number of Chinese surnames, are connected with more than 85% of the population, while the rare surnames, more than 95% of the total number of surnames, are related to only about 15% of the population. The distribution of common surnames acts as the major factor reflecting the genetic composition in different regions, and it determines the historical population migration and the degree of consanguinity between regional populations. The rare surnames are of regional characteristic and relative isolation. As a result, it is possible that the study of Chinese surnames and of the distribution pattern of population with the same surname serves as an important approaches to Chinese paternal genetics and Y chromosome evolution. This may provide valuable clue for the study of population highly subject to genetic diseases.

[Population genetics of Chinese surnames. I. Surname frequency distribution and genetic diversity in Chinese]

This paper deals with the distributional characteristics of Chinese surnames and the factors affecting their distribution. Analysis of alpha and nu values for three periods in the last 1,000 years clearly reveals the distributional pattern of Chinese surnames. In China, communities with the same surname are widespread, especially in the central areas where there are more relatively isolated Y chromosome of the same source (communities with the same surname) and more surnames than in other areas (especially the South China). If each surname has a certain kind of mono-type Y-DNA, then, according to the distribution of surnames, there exist the most mono-type of Y-DNA in the central provinces where are the originating center of Chinese surnames. For the first time, an equation is constructed predicting the kind of Chinese surnames. It has been estimated that there are about 3,100 surnames present in use for the Han nationality.

Fluvoxamine for children and adolescents with obsessive-compulsive disorder: a randomized, controlled, multicenter trial

OBJECTIVE

To determine the safety and efficacy of fluvoxamine for the treatment of children and adolescents with obsessive-compulsive disorder (OCD) with a double-blind, placebo-controlled, multicenter study.

METHOD

Subjects, aged 8 to 17 years, meeting DSM-III-R criteria for OCD were recruited from July 1991 to August 1994. After a 7- to 14-day single-blind, placebo washout/screening period, subjects were randomly assigned to fluvoxamine 50 to 200 mg/day or placebo for 10 weeks. Subjects who had not responded after 6 weeks could discontinue the double-blind phase of the study and enter a long-term, open-label trial of fluvoxamine. Analyses used an intent-to-treat sample with a last-observation-carried-forward method.

RESULTS

Mean Children's Yale-Brown Obsessive Compulsive Scale (CY-BOCS) scores with fluvoxamine were significantly (p < .05) different from those with placebo at weeks 1, 2, 3, 4, 6, and 10. Significant (p < .05) differences between fluvoxamine and placebo were observed for all secondary outcome measures at all visits. Based on a 25% reduction of CY-BOCS scores, 42% of subjects taking fluvoxamine were responders compared with 26% taking placebo. Forty-six (19 fluvoxamine, 27 placebo) of 120 randomized subjects discontinued early. Adverse events with a placebo-adjusted rate greater than 10% were insomnia and asthenia.

CONCLUSIONS

Fluvoxamine has a rapid onset of action and is well tolerated and efficacious for the short-term treatment of pediatric OCD.

Subchronic silica exposure enhances respiratory defense mechanisms and the pulmonary clearance of Listeria monocytogenes in rats

Both Listeria monocytogenes infection and silica exposure have been shown to significantly alter immune responses. In this study, we evaluated the effect of preexposure to silica on lung defense mechanisms using a rat pulmonary L. monocytogenes infection model. Male Sprague-Dawley rats were instilled intratracheally with saline (vehicle control) or silica using either an acute treatment regimen (5 mg/kg; 3 days) or a subchronic treatment protocol (80 mg/kg; 35 days). At 3 or 35 days after silica instillation, the rats were inoculated intratracheally with either approximately 5000 or 500,000 L. monocytogenes. At 3, 5, and 7 days postinfection, the left lung was removed, homogenized, and cultured on brain heart infusion agar at 37 degrees C. The numbers of viable L. monocytogenes were counted after an overnight incubation. Bronchoalveolar lavage (BAL) was performed on the right lungs, and BAL cell differentials, acellular lactate dehydrogenase (LDH) activity and albumin content were determined. Alveolar macrophage (AM) chemiluminescence (CL) and phagocytosis were assessed as a measure of macrophage function. Lung-associated lymph nodes were removed, and lymphocytes were recovered and differentiated. Preexposure to silica significantly increased the pulmonary clearance of L. monocytogenes as compared to saline controls. Exposure to silica caused significant increases in BAL neutrophils, LDH and albumin, and lymph-nodal T cells and natural killer (NK) cells in infected and noninfected rats. CL and phagocytosis were also elevated in silica-treated rats. In summary, the results demonstrated that exposure of rats to silica enhanced pulmonary immune responses, as evidenced by increases in neutrophils, NK cells, T lymphocytes, and macrophage activation. These elevations in pulmonary immune response are likely responsible for the increase in pulmonary clearance of L. monocytogenes observed with preexposure to silica.

Esterified estrogen therapy in postmenopausal women. Relationships of bone marker changes and plasma estradiol to BMD changes: a two-year study

OBJECTIVE

To determine the relationships among bone mineral density changes, bone marker changes, and plasma estrogens in postmenopausal women receiving estrogen replacement therapy.

DESIGN

A total of 406 postmenopausal women received 1,000 mg calcium and continuous esterified estrogens (0.3 mg, 0.625 mg, or 1.25 mg) or placebo daily for up to 24 months. Bone mineral density and bone marker measurements were determined at 6-month intervals; plasma estrogens were measured in a subset after 12, 18, and 24 months.

RESULTS

Esterified estrogens produced significant increases in bone mineral density (lumbar spine, hip) compared with baseline and placebo at 6, 12, 18, and 24 months. Bone markers decreased from baseline with all esterified estrogen doses relative to placebo. Bone marker changes at 6 months correlated negatively with bone mineral density changes at 24 months (correlation coefficient range = -0.122 to -0.439). The strongest correlation was noted for spine bone mineral density changes and serum osteocalcin. Mean plasma estrogen levels increased with esterified estrogen dose, and bone mineral density changes correlated positively with plasma estrogen levels. Positive bone mineral density changes were noted in treatment groups with plasma estradiol levels at and above 25 pg/mL.

CONCLUSIONS

Esterified estrogens, at doses from 0.3 mg to 1.25 mg/day, unopposed by progestin, increase bone mineral density of the spine and hip in postmenopausal women. These bone mineral density changes correlated significantly with bone marker changes at 6 months and with plasma estrogens at 12, 18, or 24 months. Data variability minimizes the predictive value of the bone marker changes in monitoring individual therapy.

Changes in F-actin organization induced by hard metal particle exposure in rat pulmonary epithelial cells using laser scanning confocal microscopy

Chronic inhalation of hard metal (WC-Co) particles causes alveolitis and the eventual development of pulmonary fibrosis. The initial inflammatory response includes a change in the alveolar epithelial cell-capillary barrier, which has been shown to be regulated by the state of assembly and organization of the actin cytoskeletal network. The objective of this study was to evaluate the effect WC-Co particles have on F-actin organization of lung epithelial cells in an in vitro culture system. Rat lung epithelial (L2) cells were exposed to 5, 25, and 100 microg/mL of WC-Co particles, as well as the individual components (Co and WC) of the hard metal mixture particles for 24 h. The effect on F-actin organization was visualized by laser scanning confocal microscopy (LSCM) following Bodipy-Phallacidin staining. Minimal changes in the F-actin microfilaments of L2 cells were observed by LSCM after exposure to WC and WC-Co at 5 and 25 microg/mL, while at 100 microg/mL, there was a noticeable disruption in the uniform distribution of L2 cell F-actin microfilaments. After exposure to Co, a dose-dependent change in the F-actin organization of the L2 cells was observed. Little change in F-actin assembly was observed after treatment with 5 microg/mL of Co (the concentration equivalent to the 5% amount of Co commonly present in 100 microg/mL of the WC-Co sample mixture). However, at 100 microg/mL of Co, the microfilaments aggregated into homogeneous masses within the cells, and a significant loss in the organization of L2 F-actin was observed. These dramatic alterations in F-actin organization seen after exposure to the higher doses of Co were attributed to an increase in L2 cell injury as measured by lactate dehydrogenase and trypan blue exclusion. We conclude the pulmonary response evoked in the lung by inhalation of high levels of WC-Co particles is unlikely due to alterations in the F-actin microfilaments of lung-epithelial cells.

Assessing the effects of global warming and local social and economic conditions on the malaria transmission

OBJECTIVE

To show how a mathematical model can be used to describe and to understand the malaria transmission.

METHODS

The effects on malaria transmission due to the impact of the global temperature changes and prevailing social and economic conditions in a community were assessed based on a previously presented compartmental model, which describes the overall transmission of malaria.

RESULTS/CONCLUSIONS

The assessments were made from the scenarios produced by the model both in steady state and dynamic analyses. Depending on the risk level of malaria, the effects on malaria transmission can be predicted by the temperature ambient or local social and-economic conditions.

Malaria transmission model for different levels of acquired immunity and temperature-dependent parameters (vector)

OBJECTIVE

Describe the overall transmission of malaria through a compartmental model, considering the human host and mosquito vector.

METHODS

A mathematical model was developed based on the following parameters: human host immunity, assuming the existence of acquired immunity and immunological memory, which boosts the protective response upon reinfection; mosquito vector, taking into account that the average period of development from egg to adult mosquito and the extrinsic incubation period of parasites (transformation of infected but non-infectious mosquitoes into infectious mosquitoes) are dependent on the ambient temperature.

RESULTS

The steady state equilibrium values obtained with the model allowed the calculation of the basic reproduction ratio in terms of the model's parameters.

CONCLUSIONS

The model allowed the calculation of the basic reproduction ratio, one of the most important epidemiological variables.