Utilization of Bt corn residues by grazing beef steers and Bt corn silage and grain by growing beef cattle and lactating dairy cows

Three experiments were conducted to evaluate the impact of the Bacillus thuringiensis (Bt)-11 transformation event in two parental corn hybrids differing in date of maturity on beef and dairy cattle performance. Sixteen lactating Holstein dairy cows in replicated 4 x 4 Latin squares were assigned to four diets in a 2 x 2 factorial arrangement: Bt vs non-Bt trait and early- vs late-maturing corn hybrids. The diets contained 40% of the test corn silage plus 28% corn grain from the same corn hybrid (DM basis). There was no effect of the Bt trait on efficiency of milk production, ruminal pH, acetate:propionate ratio, or in situ digestion kinetics of NDF. The early-maturing corn hybrids resulted in greater total VFA concentrations in the rumen and efficiency of 4% fat-corrected milk production than the later-maturing hybrids (P < 0.05). Sixty-seven steer calves were used in a 70-d corn residue grazing trial for the late-maturing corn hybrids only. Daily BW gain of steers was similar for those grazing Bt and non-Bt corn residues, and the steers exhibited no grazing preference between Bt and non-Bt corn residue. One hundred twenty-eight steer calves were assigned to four silage-based growing diets in a 2 x 2 factorial arrangement: Bt vs non-Bt trait and early- vs late-maturing corn hybrids. The diets contained 90% corn silage and 10% supplement (DM basis). The DMI was higher for steers fed Bt compared with non-Bt hybrids (P < 0.02). An interaction (P < 0.03) was observed for feed efficiency between hybrid genotype and incorporation of the Bt trait. Feed efficiency was greater (P < 0.05) for steers fed the later-maturing non-Bt hybrid compared with the later-maturing Bt hybrid; however, feed efficiency was similar between steers fed early-maturing Bt and non-Bt corn silages. Steers fed the early-maturing hybrid gained 11% faster and were 7% more efficient compared with those fed the late-maturing hybrid. These latter results agree with the dairy experiment in which the early-maturing hybrid resulted in 5% greater efficiency of milk production than the later-maturing corn hybrid. In all experiments, incorporation of the Bt trait into corn had no consistent effect on cattle performance. In addition, background genetics of the corn hybrids appeared to have a more consistent impact on performance than did presence of the Bt trait.

An epidemiological study of the respiratory health of workers in the European refractory ceramic fibre industry

OBJECTIVES

To investigate possible relations between respiratory health and past airborne exposure to refractory ceramic fibres (RCFs) and respirable dust in workers at six European factories, studied previously in 1987.

METHODS

The target population comprised all current workers associated with RCF production, plus others who had participated in 1987 "leavers". Information was collected on personal characteristics, chest radiographs, lung function, respiratory symptoms, smoking, and full occupational history. Regression analysis was used to study relations between indices of health of individual workers and of cumulative exposure to airborne dust and fibres, and likely past exposure to asbestos.

RESULTS AND DISCUSSION

774 workers participated (90% of current workers, 37% of leavers). Profusion of small opacities in exposed workers (51% 0/1+; 8% 1/0+) was similar to that among an unexposed control group but higher than in new readings of the 1987 study films (11% 0/1+, 2% 1/0+). The large difference between 1987 and recent films may be, at least in part, a reading artefact associated with film appearance. Small opacities of International Labour Organisation (ILO) category 1/0+ were not associated with exposure. An association of borderline significance overall between 0/1+ opacities and exposure to respirable fibres was found for some exposure periods only, the time related pattern being biologically implausible. Pleural changes were related to age and exposure to asbestos, and findings were consistent with an effect of time since first exposure to RCFs. Among men, forced expired volume in 1 second (FEV(1)) and forced vital capacity (FVC) were inversely related to exposure to fibres, in current smokers only. FEV(1)/ FVC ratio and transfer factor (TL(CO)) were not related to exposures. The estimated restrictive effect was on average mild. Prevalence of respiratory symptoms was low. Chronic bronchitis and its associated symptoms (cough, phlegm) showed some association with recent exposure to respirable fibres. This could be due to an irritant effect of RCFs.

The role of endogenous opioids in moderate exercise training-induced enhancement of the secondary antibody response in mice

BACKGROUND AND PURPOSE

Moderate exercise training (60%-80% of maximal oxygen uptake) enhances the secondary antibody response. The mechanism underlying this enhancement, however, has not been determined. In moderate doses, endogenous opioids such as enkephalins enhance antibody response. Furthermore, serum concentrations of endogenous opioids increase in response to exercise, and training programs augment this effect. Therefore, the enhancement of the secondary antibody response induced by moderate exercise may be brought about, in part, by endogenous opioids. The purpose of this study was to examine the effects of naltrexone (an opioid antagonist) on the enhancement of secondary antibody response induced by moderate exercise in young mice.

SUBJECTS AND METHODS

C57BL/6 mice immunized to human serum albumin (HSA) were randomly assigned to 1 of 3 groups: naltrexone, placebo, or control (received no intervention). Then, the mice in each group were randomly assigned to either an exercise group (treadmill running at 15 m/min, 0ø slope, 5 days per week for 8 weeks) or a non-exercise group. At the end of 8 weeks, booster immunization was given, and the mice in the exercise group continued to exercise. Ten days later, when high levels of antibodies are produced in secondary antibody response, anti-HSA antibodies in serum were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

With naltrexone implantation, mice that exercised showed a depression of secondary antibody response as compared with mice that exercised and either received a placebo or did not receive any intervention.

DISCUSSION AND CONCLUSION

Endogenous opioids may play a role in the enhancement of the secondary antibody response observed after moderate exercise.

A noninvasive method to collect nasally exhaled air condensate in humans of all ages

BACKGROUND

The analysis of exhaled breath condensate may provide valuable insights into inflammatory and other metabolic processes of the lungs. However, its collection by active exhalation with conventional methods is cumbersome, demands a substantial level of co-operation with high motivation and is very difficult or impossible in children younger than about 4-6 years or in the elderly. A comfortable, noninvasive and efficient method is desirable.

DESIGN AND PATIENTS

For collection a high-performance pump connected to a cold trap and nasal prongs were used. The volume of the condensate collected was assessed in 141 children of all ages and five adults. As an example for a low molecular component, H2O2 a marker of oxidative stress, was determined fluorometrically.

RESULTS

On average, in healthy children from 4 weeks to 18 years of age, 84.0 (79.4, 87.3) microL min(-1) of nasally exhaled air condensate were collected. The volume obtained was about 45% less in 1-6-year-old children, increased linearly with collection time, and averaged about 20-30% of the exhaled water vapour. The concentration of H2O2 in the healthy children was 0.49 (0.48, 0.61) microM and did not depend on age, the time of the day, family, or personal history of atopy and sex.

CONCLUSIONS

The method described is generally applicable, comfortable, noninvasive, safe and efficient and allows the collection of nasally exhaled air condensate for the evaluation of metabolic processes of the lungs.

Comparison of corn silage hybrids for yield, nutrient composition, in vitro digestibility, and milk yield by dairy cows

A study was undertaken to compare Novartis N29-F1, a dual-purpose 90-d relative maturity corn hybrid, and Novartis NX3018, a 90-d relative maturity leafy corn silage hybrid for dry matter (DM) yield, in vitro digestibility, plant components, nutrient composition, and lactational performance by Holstein cows. The two corn hybrids were planted in replicated 15.2- x 321-m plots. Plant population and DM yield were similar between the two corn hybrids. Novartis NX3018 had higher content of crude protein and ash, a higher proportion of leaves and stalks, and a lower proportion of grain compared with Novartis N29-F1. The cob, grain, and leaves of Novartis NX3018 had higher in vitro true DM and neutral detergent fiber disappearances compared with the respective plant components of Novartis N29-F1. Thirty-eight midlactation multiparous Holstein cows (78 +/- 23.0 days in milk) producing 47.2 +/- 8.9 kg of milk per cow per day were blocked and assigned randomly to one of two total mixed ration (TMR) containing (DM basis) approximately 26% Novartis N29-F1 or Novartis NX3018 corn silage. Cows were housed in a free-stall barn and group fed ad libitum. The lactation study was conducted as a crossover design with two 28-d periods. Samples and data were collected during the final 7 d of each period. The total mixed rations were formulated using the Cornell-Penn-Miner Dairy nutrition model. Cows that were fed the total mixed rations containing Novartis NX3018 corn silage produced higher yields of milk 3.5% fat-corrected milk (FCM), milk crude protein, and milk lactose compared to cows that were fed the TMR containing Novartis N29-F1 corn silage. In conclusion, the Novartis NX3018 corn hybrid was leafier and more digestible in vitro, and when fed to dairy cows as silage, promoted higher milk yield compared with the Novartis N29-F1 corn hybrid.

Influence of the bradykinin B1/B2-receptor-antagonist B 9430 on the cerebral microcirculation and outcome of gerbils from global cerebral ischemia

The influence of the bradykinin B1/B2 antagonist B 9430 on the cerebral microcirculation following global cerebral ischemia was investigated in a closed cranial window preparation in Mongolian gerbils by intravital fluorescence microscopy. Global cerebral ischemia (GCI) was induced by occlusion of both common carotid arteries for 15 min. Leukocyte-endothelium interactions, vessel diameters, and the segmental microvascular blood flow were observed by intravital microscopy before and up to three hours after global cerebral ischemia. Following the early reperfusion period the animals survived up to 4 days after ischemia. The neurological deficit and the body weight were assessed daily. On day 4 animals were subjected to perfusion fixation and the brain was removed. Nerve cell damage from ischemia was quantified histologically in cortex, hippocampus, and striatum. Animals with treatment received the bradykinin B1/B2 receptor antagonist B 9430 before (i.v.), during, and after ischemia (s.c.) until the end of the experiment. The frequency of leukocytes (cells/100 microns x min) rolling along the venular endothelium post ischemia was significantly decreased (p < 0.05) in treated animals as compared to untreated controls (33.0 +/- 6.2 vs. 8.5 +/- 2.3) as well as the number of leukocytes attached to the endothelial surface (7.2 +/- 3.0 vs. 2.0 +/- 1.0, n.s.). The neuroscore on day 4 (pre-ischemic control: 22 points) was reduced to 13.4 +/- 3.2 in untreated animals, while to 4.7 +/- 3.2 points in the treatment group. No differences between animals with and without treatment were found as to the number of viable neurons. Although bradykinin is released in the brain during global cerebral ischemia, its antagonisation does not improve outcome despite the effective inhibition of leukocyte-endothelium interactions.

Prevention and early detection of type 2 diabetes in children and adolescents

Type 2 ("adult-onset") diabetes in young adults and children has become increasingly common over the last 10 years, and has been described as an "emerging epidemic." The financial and societal ramifications of such a development are substantial and demand a prompt and aggressive public health response. Emphasis must be placed upon preventive behaviors and early detection, and creation of new public policy to address the related societal issues. Recommendations for prevention and screening of high-risk children and adolescents are provided.

Reconstitution of a functional duck hepatitis B virus replication initiation complex from separate reverse transcriptase domains expressed in Escherichia coli

Hepatitis B viruses replicate through reverse transcription of an RNA intermediate, the pregenomic RNA (pgRNA). Replication is initiated de novo and requires formation of a ribonucleoprotein complex comprising the viral reverse transcriptase (P protein), an RNA stem-loop structure (epsilon) on the pgRNA, and cellular proteins, including the heat shock protein Hsp90, the cochaperone p23, and additional, as yet unknown, factors. Functional complexes catalyze the synthesis of a short DNA primer that is templated by epsilon and covalently linked to the terminal protein (TP) domain of P protein. Currently, the only system for generating such complexes in the test tube is in vitro translation of duck hepatitis B virus (DHBV) P protein in rabbit reticulocyte lysate (RRL), which also provides the necessary factors. However, its limited translation capacity precludes a closer analysis of the complex. To overcome this restriction we sought to produce larger amounts of DHBV P protein by expression in Escherichia coli, followed by complex reconstitution in RRL. Because previous attempts to generate full-length P protein in bacteria have failed we investigated whether separate expression of the TP and reverse transcriptase-RNase H (RT-RH) domains would allow higher yields and whether these domains could trans complement each other. Indeed, TP and, after minor C-terminal modifications, also RT-RH could be expressed in substantial amounts, and when added to RRL, they were capable of epsilon-dependent DNA primer synthesis, demonstrating posttranslational activation. This reconstitution system should pave the way for a detailed understanding of the unique hepadnaviral replication initiation mechanism.

Electrical activity of the diaphragm during pressure support ventilation in acute respiratory failure

We compared crural diaphragm electrical activity (EAdi) with transdiaphragmatic pressure (Pdi) during varying levels of pressure support ventilation (PS) in 13 intubated patients. With changing PS, we found no evidence for changes in neuromechanical coupling of the diaphragm. From lowest to highest PS (2 cm H(2)O +/- 4 to 20 cm H(2)O +/- 7), tidal volume increased from 430 ml +/- 180 to 527 ml +/- 180 (p < 0.001). The inspiratory volume calculated during the period when EAdi increased to its peak did not change from 276 +/- 147 to 277 +/- 162 ml, p = 0.976. Respiratory rate decreased from 23.9 (+/- 7) to 21.3 (+/- 7) breaths/min (p = 0.015). EAdi and Pdi decreased proportionally by adding PS (r = 0.84 and r = 0.90, for mean and peak values, respectively). Mean and peak EAdi decreased (p < 0.001) by 33 +/- 21% (mean +/- SD) and 37 +/- 23% with the addition of 10 cm H(2)O of PS, similar to the decrease in the mean and peak Pdi (p < 0.001) observed (34 +/- 36 and 35 +/- 23%). We also found that ventilator assist continued during the diaphragm deactivation period, a phenomenon that was further exaggerated at higher PS levels. We conclude that EAdi is a valid measurement of neural drive to the diaphragm in acute respiratory failure.

A rodent model of alcoholic heart muscle disease and its evaluation by echocardiography

BACKGROUND

Transthoracic echocardiography was used in a rodent animal model to determine whether long-term alcohol consumption (8 and 12 months) was associated with the development of a dilated cardiomyopathy. We also investigated whether alcohol-induced changes in cardiac structure corresponded to activation of the renin-angiotensin system and the natriuretic peptide (NP) system.

METHODS

Male rats received either the Lieber-DeCarli liquid alcohol diet (EtOH) (9%v/v) (n = 8) or control diet (CON) (n = 8). Echocardiography (echo) was used to determine left-ventricular (LV) dimensions, and isolated heart studies (Langendorff and atrium) were used to assess ex vivo contractility. Plasma and tissue angiotensin-I converting enzyme (ACE) activity was measured. Gene expression, plasma, and tissue levels of the NPs were determined by northern blot analysis and radioimmunoassay, respectively.

RESULTS

After 8 months of alcohol consumption, there was a trend for the end diastolic dimension, end systolic dimension, and LV mass to be greater in the 8 month EtOH group compared with the CON group. However, after 12 months of alcohol consumption, significant increases were found between the groups in several echo parameters. Tissue ACE activity (nmoles/min/mg protein) was greater in the 12 month EtOH group compared with the 12 month CON and 8 month EtOH group (p < 0.05). We found no differences between groups in gene expression (messenger RNA), plasma, and tissue levels of the NPs.

CONCLUSIONS

Echocardiography revealed that 8 to 12 months of alcohol consumption was associated with the development of a dilated cardiomyopathy. However, this was not preceded by an increase in tissue ACE activity, and these changes occurred in the absence of increased plasma and LV tissue levels of the NPs.

Uptake of a natural surfactant and increased delivery of small organic anions into type II pneumocytes

The uptake of natural lung surfactant into differentiated type II cells may be used for the targeted delivery of other molecules. The fluorescent anion pyranine [hydroxypyren-1,3,6-trisulfonic acid, sodium salt (HPTS)] was incorporated into a bovine surfactant labeled with [3H]dipalmitoylphosphatidylcholine ([3H]DPPC). The uptake of [3H]DPPC and of HPTS increased with time of incubation and concentration, decreased with the size of the vesicles used, and was stimulated by 8-bromo-cAMP and partially inhibited by hypertonic sucrose. However, the amount of HPTS uptake was approximately 100 times smaller than that of [3H]DPPC. This large difference was due to a more rapid regurgitation of some of the HPTS from the cells but not to leakage from the surfactant before uptake. The acidification of the internalized surfactant increased linearly over 90 min to 7.13, and after 24 h, a pH of 6.83 was measured. In conclusion, after internalization of a double-labeled natural surfactant, the lipid moieties were accumulated in relation to the anions, which were targeted to a compartment not very acidic and in part rapidly expelled from the cells.

Autopsy-confirmed familial early-onset Alzheimer disease caused by the l153V presenilin 1 mutation

BACKGROUND

Three affected individuals are described from a small English kindred with early-onset autosomal dominant familial Alzheimer disease (FAD) caused by a leucine-to-valine change at codon 153 (L153V) of the presenilin 1 (PSEN1) gene.

METHODS

Clinical information on the pedigree was collected directly from family members and from hospital records. Samples of DNA were screened by means of direct sequencing of all coding exons of PSEN1. One patient underwent neuropathological examination.

RESULTS

Mean age at onset of symptoms was 35.3 years (95% confidence interval [CI], 34.6-36.0 years); at death, 44.0 years (95% CI, 39.1-48.9 years). Mean duration of illness was 8.3 years (95% CI, 4.7-11.9 years). Myoclonus was a late feature in 1 patient; seizures were not reported in any subjects. Spastic paraparesis and extrapyramidal signs were absent. The neuropsychometric profile of 1 patient showed relatively preserved naming skills in the setting of global cognitive deficits. Results of neuropathological examination demonstrated the signature lesions of Alzheimer disease and the presence of occasional cortical Lewy bodies.

CONCLUSIONS

The PSEN1 L153V mutation lies in the main mutation cluster of PSEN1 in the second transmembrane domain. It causes early-onset FAD with clinical features similar to those of other reported FAD pedigrees.

Diaphragm activation during exercise in chronic obstructive pulmonary disease

Although it has been postulated that central inhibition of respiratory drive may prevent development of diaphragm fatigue in patients with chronic obstructive pulmonary disease (COPD) during exercise, this premise has not been validated. We evaluated diaphragm electrical activation (EAdi) relative to maximum in 10 patients with moderately severe COPD at rest and during incremental exhaustive bicycle exercise. Flow was measured with a pneumotachograph and volume by integration of flow. EAdi and transdiaphragmatic pressures (Pdi) were measured using an esophageal catheter. End-expiratory lung volume (EELV) was assessed by inspiratory capacity (IC) maneuvers, and maximal voluntary EAdi was obtained during these maneuvers. Minute ventilation (V E) was 12.2 +/- 1.9 L/min (mean +/- SD) at rest, and increased progressively (p < 0.001) to 31.0 +/- 7.8 L/min at end-exercise. EELV increased during exercise (p < 0.001) causing end-inspiratory lung volume to attain 97 +/- 3% of TLC at end-exercise. Pdi at rest was 9.4 +/- 3.2 cm H(2)O and increased during the first two thirds of exercise (p < 0.001) to plateau at about 13 cm H(2)O. EAdi was 24 +/- 6% of voluntary maximal at rest and increased progressively during exercise (p < 0.001) to reach 81 +/- 7% at end-exercise. In conclusion, dynamic hyperinflation during exhaustive exercise in patients with COPD reduces diaphragm pressure-generating capacity, promoting high levels of diaphragm activation.

Desflurane pharmacokinetics during cardiopulmonary bypass

OBJECTIVE

To describe the washin and washout of desflurane when first administered during cardiopulmonary bypass (CPB) for cardiac surgery.

DESIGN

A single-arm prospective study.

SETTING

University-affiliated hospital operating room.

PARTICIPANTS

Ten adult patients presenting for cardiac surgery.

INTERVENTIONS

Consenting patients presenting for cardiac surgery received anesthesia with midazolam and fentanyl. Patients were cooled to 32 degrees C on CPB, then desflurane 6% was administered and blood samples drawn repeatedly from the arterial and venous bypass cannulae as well as from the membrane oxygenator inlet and exhaust from 2 to 32 minutes of desflurane administration. Just before rewarming, final (maximum) washin samples were taken. On rewarming, desflurane was discontinued, and blood and gas samples were taken 2 to 24 minutes thereafter.

MEASUREMENTS AND MAIN RESULTS

CPB time was 116 +/- 10 minutes, and ischemic time was 81 +/- 6 minutes. Mean pump flow was 4.49 +/- 0.03 L/min, and mean arterial pressure was 70.1 +/- 1 mmHg during the study period. Arterial washin of desflurane was initially rapid; arterial concentrations reached 50% of administered concentrations within 4 minutes, but then slowed, reaching 68% of inspired concentrations at 32 minutes (desflurane concentration 4.0% +/- 0.3%). Arterial washout of desflurane was more rapid; arterial concentrations fell to 18% of the maximum concentration reached within 4 minutes, and only 8% of the maximum arterial concentration was present in blood 20 minutes later.

CONCLUSION

Desflurane showed rapid initial washin and washout on CPB when administration was started at 32 degrees C and stopped at time of rewarming.

Correlates of knowledge of one's blood pressure and cholesterol levels among older members of a managed care plan

We examined factors predicting knowledge of one's blood pressure, total cholesterol, and high-density lipoprotein levels (HDL) among older persons who reported a recent blood pressure or cholesterol test. Data come from a self-administered, health risk assessment that was mailed to health plan members, age 55 and older, in a Santa Barbara, California medical group. Despite their universal access to health care and high levels of reported compliance with preventive health care screening practices, 41%, 49%, and 77% of respondents reported that they did not know their blood pressure, cholesterol, or HDL levels, respectively. After controlling for potential confounders, age and low income were inversely associated with the respondents' ability to report each level. In addition, current smoking and obesity were inversely associated with self-reported knowledge of both cholesterol measures. Persons taking medication for hypertension or hypercholesterolemia were much more likely than those not taking medication to be able to report their blood pressure and cholesterol levels. Except for persons currently undergoing treatment for related conditions, these results suggest that a substantial proportion of the older persons at high risk for cardiovascular disease do not know their levels of these important biological risk factors. This lack of knowledge has important implications for public health education, and may hinder risk-reduction efforts among the elderly.

Changes in respiratory effort sensation over time are linked to the frequency content of diaphragm electrical activity

This study evaluated whether respiratory effort sensation (RES) changes over time when breathing is performed with constant contraction pattern, fixed diaphragm activation, and maintained pressure generation. Another aim was to assess whether there was any association between RES and the power spectrum center frequency of the diaphragm (CFdi) electrical activity. Six healthy subjects performed two 10-min periods targeting diaphragm electrical activation (EAdi) to 40% of maximum using (1) expulsive or Mueller maneuvers at FRC generating a mean transdiaphragmatic (Pdi) pressure of 55.0 +/- 22.7 cm H(2)O (+/- SD) and (2) inspiration to 71.2 +/- 14.1% of inspiratory capacity (IC) generating a Pdi of 21.4 +/- 5.2 cm H(2)O. The Pdi did not decrease over time during either maneuver. During both periods RES increased (p < 0.001) and CFdi decreased (p < 0.001) over time with higher Pdi levels producing larger decreases in CFdi (p = 0.003) and greater increases in RES (p = 0.008). Changes in CFdi and RES were related, and identical slopes were obtained during the two maneuvers. In conclusion, while breathing with a fixed pattern, constant diaphragm activation, and maintained pressure generation, RES increases over time and is associated with CFdi independent of the level of diaphragm pressure generated.

Alteration of the vascular supply in the rabbit ciliary body by transscleral diode laser cyclophotocoagulation

BACKGROUND

Besides the direct destruction of the non-pigmented ciliary epithelium by cyclodestructive procedures, further mechanisms are responsible for the decrease of intraocular pressure. This study evaluates the alteration of the ciliary body vascularization by contact transscleral diode laser cyclophotocoagulation in rabbit eyes.

METHODS

Pigmented chinchilla bastard rabbits were used. Preliminary experiments were conducted to determine the parameters for diode laser cyclophotocoagulation of the pars plana or pars plicata. Then, treatment of the pars plicata (three rabbits) or pars plana (three rabbits) was performed in the right eye of six rabbits. After 2, 6 and 12 weeks histologic and transmission electron microscopic studies were performed. Furthermore, three rabbits received pars plicata cyclophotocoagulation of the right and pars plana cyclophotocoagulation of the left eye. After 2, 6 and 12 weeks, vascular casts of the ciliary body were investigated by scanning electron microscopy.

RESULTS

Histologic and transmission electron microscopic studies showed a marked coagulation necrosis with subsequent ciliary body atrophy, destruction of the ciliary epithelium, pigment dispersion in the ciliary body stroma and peripheral anterior synechiae. Examination of vascular casts of the ciliary body revealed a marked rarefication of the capillary network within the treated areas of the ciliary body in all eyes and at every time of investigation. Anterior to the laser burns the capillary network was not markedly affected in the eyes with cyclophotocoagulation of the pars plana. After 3 months short vessel sprouts were seen, but regeneration was mostly incomplete.

CONCLUSIONS

The vascular casting technique is an excellent method for the investigation of changes in ciliary body vascularization after cyclodestruction. This study is the first to demonstrate a marked rarefication of the ciliary body vascularization after diode laser cyclophotocoagulation using vascular casts. The results suggest that alteration of vascularization probably acts as a strong synergistic mechanism in the decrease of intraocular pressure after cyclophotocoagulation of the pars plicata.

Hg3AsE4X (E = S, Se; X = Cl, Br, I), a family of isotypic compounds with an acentric, layered structure

Four isotypic compounds Hg3AsS4Cl, Hg3AsS4Br, Hg3AsSe4Br, and Hg3AsSe4I were synthesized in the quaternary system mercury/arsenic/chalcogen/halogen by vapor transport reactions from As, Hg(II) halide, Hg(II) chalcogenide, and elemental chalcogen at temperatures between 250 and 310 degrees C. Their structures were solved by single-crystal X-ray diffraction analyses. The compounds crystallize in the hexagonal system with the acentric space group P63mc and the following lattice parameters: a = 7.431(5) A, c = 9.003(8) A for Hg3AsS4Cl, a = 7.430(5) A, c = 9.364(5) A for Hg3AsS4Br, a = 7.707(8) A, c = 9.47(2) A for Hg3AsSe4Br, and a = 7.6902(7) A, c = 9.968(1) A for Hg3AsSe4I, and Z = 2. All compounds are air-stable and form hexagonal prismatic crystals. The colors vary from yellow (Hg3AsS4Cl) to red (Hg3AsSe4I). The structures consist of infinity 2[Hg3AsE4]+ polycationic layers built of six-membered Hg3E3 and Hg2AsE3 rings in chair and boat conformations. Alternatively, the structure of the layers can be described as composed of [AsE3]3- and [Hg3E]4+ ions both forming regular trigonal pyramids. The halide ions are intercalated between the layers and have only weak bonds to the mercury atoms. The acentricity of the structures was confirmed through SHG measurements using IR laser radiation (lambda = 1064 nm).

Characterization of osteoclast precursors in human blood

Osteoclast precursors (OCPs) circulate in the mononuclear fraction of peripheral blood (PB), but their abundance and surface characteristics are unknown. Previous studies suggest that the receptor activator for NF-kappaB (RANK) on cytokine-treated OCPs in mouse bone marrow interacts with osteoprotegerin ligand (OPGL/TRANCE/RANKL/ODF) to initiate osteoclast differentiation. Hence, we used a fluorescent form of human OPGL (Hu-OPGL-F) to identify possible RANK-expressing OCPs in untreated peripheral blood mononuclear cells (PBMCs) using fluorescence-activated cell sorting analysis. Monocytes [CD14-phycoerythrin (PE) antibody (Ab) positive (+) cells, 10-15% of PBMCs] all (98-100%) co-labelled with Hu-OPGL-F (n > 18). T lymphocytes (CD3-PE Ab+ cells, 66% of PBMCs) did not bind Hu-OPGL-F; however, B cells (CD19-PE Ab+ cells, 9% of PBMCs) were also positive for Hu-OPGL-F. All Hu-OPGL-F+ monocytes also co-labelled with CD33, CD61, CD11b, CD38, CD45 and CD54 Abs, but not CD34 or CD56 Abs. Hu-OPGL-F binding was dose dependent and competed with excess Hu-OPGL. When Hu-OPGL-F+, CD14-PE Ab+, CD33-PE Ab+, Hu-OPGL-F+/CD14-PE Ab+ or Hu-OPGL-F+/CD33-PE Ab+ cells were cultured with OPGL (20 ng/ml) and colony-stimulating factor (CSF)-1 (25 ng/ml), OC-like cells readily developed. Thus, all freshly isolated monocytes demonstrate displaceable Hu-OPGL-F binding, suggesting the presence of RANK on OCPs in PB; also, OCPs within a purified PB monocyte population form osteoclast-like cells in the complete absence of other cell types in OPGL and CSF-1 containing medium.

Glutathione S-transferase and drug sensitivity in malignant glioma

Malignant gliomas are largely resistant to current approaches of adjuvant chemotherapy. Gluthatione S-transferases (GST) have been attributed a role in the resistance of cancer cells, e.g., to nitrosoureas. Here, we assessed the expression levels of GST-pi and GST-mu RNA and protein as well as total GST activity in a panel of 12 human glioma cell lines and correlated these data with p53 status, BCL-2 family protein expression and drug sensitivity in these cells. Neither GST protein levels nor GST activity correlated with genetic or functional p53 status or with the expression of various BCL-2 family proteins. No evidence for GST-mediated protection from chemotherapeutic drugs became apparent. In contrast, high levels of GST-pi protein, probably the major source of GST activity in glioma cells, and of total GST activity correlated with enhanced sensitivity to vincristine-induced clonogenic cell death. Expression of GST-pi in human glioblastomas in vivo was confirmed by immunohistochemistry. Neither total, nor cytoplasmic or nuclear, GST-pi immunoreactivity correlated with the response to adjuvant radiotherapy or radiochemotherapy. A comparative analysis of primary and recurrent tumors showed that GST expression was not enhanced by radiochemotherapy in vivo. We conclude that GST does not account for the differential chemosensitivity of glioma cell lines in vitro and does not accumulate in glioma subpopulations that form recurrent tumors after radiochemotherapy in vivo.

Expiratory muscle pressure and breathing mechanics in chronic obstructive pulmonary disease

Expiratory muscle recruitment is common in stable chronic obstructive pulmonary disease (COPD) patients. Due to airway obstruction, there is little reason to believe that active expiration in COPD would be mechanically effective in lowering operating lung volume. The physiological significance of expiratory muscle recruitment in COPD, therefore, remains unknown. The purpose of this study was to assess, in COPD patients breathing at rest, the effect of expiratory muscle contraction on force generating ability of the diaphragm. The force generating ability of the diaphragm was evaluated from its pressure swing (Pdi) for a given diaphragm electrical activity (Edi), where Edi was normalized as % of its maximal value (Pdi/Edi/Edi,max). Phasic expiratory muscle contraction was measured as the total expiratory rise in gastric pressure (Pga,exp.rise). Nineteen seated patients with moderate to severe COPD, participated in the study and 10 exhibited phasic rise in Pga during expiration with a mean Pga,exp.rise of 1.91+/-0.89 cmH2O. The patients were thus divided into passive expiration (PE) and active expiration (AE) groups. There was no significant difference in various lung function and breathing pattern parameters between the two groups. Pdi/Edi/Edi,max was 0.63+/-0.07 and 0.54+/-0.07 cmH2O/% in PE and AE groups, respectively, and was not significantly different between each other. Compared with PE group, AE group not only recruited expiratory muscles, but also preferentially recruited inspiratory rib cage muscles and derecruited the diaphragm. The results do not support a significant improvement of the force-generating ability of the diaphragm by phasic contraction of expiratory muscles at rest in chronic obstructive pulmonary disease patients.