Effect of dirithromycin on Haemophilus influenzae infection of the respiratory mucosa

Macrolides have properties other than their antibiotic action which may benefit patients with airway infections. We have investigated the effect of dirithromycin (0.125 to 8.0 microg/ml) on the interaction of Haemophilus influenzae with respiratory mucosa in vitro using human nasal epithelium, adenoid tissue, and bovine trachea. Dirithromycin did not affect the ciliary beat frequency of the nasal epithelium or the transport of mucus on bovine trachea, but dirithromycin (1 microg/ml) did reduce the slowing of the ciliary beat frequency and the damage to the nasal epithelium caused by H. influenzae broth culture filtrate. Amoxicillin (2 microg/ml) did not reduce the effects of the H. influenzae broth culture filtrate. H. influenzae infection of the organ cultures for 24 h caused mucosal damage and the loss of ciliated cells. Bacteria adhered to damaged epithelium and to a lesser extent to mucus and unciliated cells. Incubation of H. influenzae with dirithromycin at sub-MICs (0.125 and 0.5 microg/ml) prior to infection of the organ cultures did not reduce the mucosal damage caused by bacterial infection. By contrast, incubation of adenoid tissue with dirithromycin (0.125 to 1.0 microg/ml) for 4 h prior to assembling the organ culture reduced the mucosal damage caused by subsequent H. influenzae infection by as much as 50%. The number of bacteria adherent to the mucosa was reduced, although the tissue that had been incubated with dirithromycin (0.125 and 0.5 microg/ml) did not inhibit bacterial growth. This was achieved by a reduction in the amount of damaged epithelium to which H. influenzae adhered and a reduction in the density of bacteria adhering to mucus. We conclude that dirithromycin at concentrations achievable in vivo markedly reduces the mucosal damage caused by H. influenzae infection due to a cytoprotective effect.

Erythrocyte glutathione balance and membrane stability during preeclampsia

This study aimed to determine whether oxidative damage to the erythrocyte occurs in preeclampsia, and relates to disease severity. The oxidative status of intact erythrocytes from preeclamptic patients and normal pregnant women was determined using spin echo 1H-NMR, which measures both the concentration and redox state of intracellular glutathione. Previous studies of preeclampsia have only measured total glutathione levels. Membrane fragility was determined from the degree of lysis caused by incubation in hypotonic saline. Erythrocytes from moderate-severe preeclamptic patients underwent more lysis than erythrocytes from control pregnant women (p < .05) or mild preeclamptic patients. It is suggested that increased lysis results from oxidative damage to the erythrocyte membrane, causing a decrease in membrane fluidity and reducing its ability to withstand osmotic changes. Intracellular glutathione was more oxidized in erythrocytes from pregnant women compared to nonpregnant controls (p < .05), and there was a less significant trend toward more oxidized glutathione with increasing severity of preeclampsia. The moderate-severe group showed a clear division in glutathione redox status: some patients had very oxidized glutathione while others had a normal redox balance. This novel finding suggests that some patients may be unusually susceptible to erythrocyte glutathione oxidation, possibly leading to general cellular damage, in particular HELLP Syndrome.

Practice choices of graduating family medicine residents

OBJECTIVE

To examine the types of practices family medicine residents chose during the first 2 years after residency, and how these choices have changed over a 15-year period.

DESIGN

Mailed survey.

SETTING

Areas served by graduates of the Queen's University family medicine residency program.

PARTICIPANTS

Two hundred thirty (76%) of the 303 graduates from 1977 to 1991 of the Queen's University family medicine residency program responded to the questionnaire.

MAIN OUTCOME MEASURES

Type of practices residents entered immediately out of residency: whether they began full-time, part-time, locum tenens, or other type of practice; length of time spent in the first practice situation; and proportion of residents who had settled into a full-time practice within 2 years of completing residency.

RESULTS

Residents who graduated before 1985 were significantly more likely to go into full-time practice immediately out of residency (P = .0001). The earlier residents had graduated from the program, the more likely they were to go immediately into full-time practice. This finding was not affected by residents' age, sex, size of community of origin, exposure to rural teaching sites, marital status, or how well prepared for practice they felt. Residents graduating before 1985 were also more likely to be in full-time practice within 2 years of completing their residency program (P = .003).

CONCLUSIONS

Recent family medicine residents did not enter full-time practice immediately out of residency as often as those who had graduated earlier, nor did they commit to full-time practice within 2 years of graduating as often as residents graduating before 1985 did.

Oxidation of erythrocyte glutathione by monocytes stimulated with interleukin-6. Analysis by 1H spin echo NMR

1H spin echo NMR was used to follow the release of reactive oxygen species (ROS) from human monocytes by monitoring erythrocyte glutathione status, which is sensitive to applied oxidative stress. This allowed the ability of the cytokine interleukin-6 (IL-6) to stimulate release of ROS from monocytes to be assessed in terms of oxidative damage to other cells, providing an estimation of its importance in vivo. It was found that incubation of monocytes with erythrocytes in the presence of IL-6 resulted in oxidation of the erythrocyte glutathione pool, indicating that oxidants are released in sufficient amounts to cause oxidative stress. High levels of IL-6 occurring in plasma of women with severe pre-eclampsia could therefore be responsible for depleted plasma antioxidants and haemolysis. The oxidation of erythrocyte glutathione was inhibited by the presence of the cyclooxygenase inhibitor indomethacin, suggesting that this may be of value in the treatment of oxidative pathologies.

Lack of morphine and enkephalin tolerance in 129/SvEv mice: evidence for a NMDA receptor defect

In contrast to the rapid development of tolerance to morphine in CD-1 mice, tolerance is not seen in 129/SvEv mice implanted with morphine pellets or given daily morphine injections for 5 days. Similarly, the progressive and complete loss of analgesia in CD-1 mice seen with repeated dosing of the delta ligand [D-Pen2, D-Pen5]enkephalin is not observed in 129/SvEv mice. In contrast, tolerance develops normally to both the kappa1 drug U50,488H and the kappa3 agent naloxone benzoylhdrazone. N-methyl-D-aspartate (NMDA) given alone attenuates morphine analgesia in CD-1 mice and accelerates the development of tolerance in CD-1 mice when given daily with morphine. In contrast, NMDA has no significant effect in the 129/SvEv mice in either paradigm. Activation of NMDA receptors can lead to the production of nitric oxide, which also is involved with morphine tolerance. Sodium nitroprusside and L-arginine increase nitric oxide levels and decrease morphine analgesia in both the control CD-1 and 129/SvEv mice. Thus, the defect in the NMDA/nitric oxide cascade responsible for the loss of morphine tolerance in the 129/SvEv mice rests at the level of the NMDA receptor itself or in the steps up to the activation of nitric oxide synthase.

Effect of salmeterol on Haemophilus influenzae infection of respiratory mucosa in vitro

Haemophilus influenzae is a common bacterial pathogen causing human respiratory tract infections. We have previously shown that the beta2-agonist salmeterol reduces damage to the respiratory mucosa caused by Pseudomonas aeruginosa in vitro. We have now investigated the effect of salmeterol on H. influenzae infection of adenoid tissue in an organ culture by scanning electron microscopy. Tissue was preincubated with or without salmeterol (4x10(-7)M), prior to infection with H. influenzae and incubated for 12 or 24 h. Infected organ cultures had increased epithelial damage and decreased numbers of both ciliated and unciliated cells at 12h, which were significantly different (p < or = 0.01) from the controls at 24 h. Salmeterol (4x10(-7)M) significantly (p < or = 0.03) reduced damage and loss of ciliated cells in infected organ cultures at both 12 and 24, and significantly (p < or = 0.03) reduced loss of unciliated cells at 24 h. Salmeterol had no effect on the density of bacteria adhering to each individual mucosal feature or the total number of bacteria adhering to the organ culture. These results suggest that salmeterol protects the respiratory epithelium against Haemophilus influenzae-induced damage. The mechanism of salmeterol cytoprotection and its potential clinical relevance remain to be investigated.

A two-component model of texture for analysis and synthesis

A model of natural texture based on a structural component that uses affine coordinate transformations and a stochastic residual component is presented. It is argued that the selection of an appropriate analysis scale can be formulated in terms of a tradeoff between the rate at which parameters are generated and the distortion resulting from the approximation by the structural component. An efficient algorithm for identifying the parameters of the structural model is described and its utility demonstrated on a number of synthetic and natural textures.

Myocrisin-mediated oxidative stress

This study reports on the ability of myocrisin to mediate in the production and detoxification of oxidants (principally hydrogen peroxide) in the monocyte in-vivo and in-vitro. The hydrogen peroxide produced by the monocyte derived from rheumatoid arthritis patients being treated with myocrisin was found to be 14.9 +/- 1.6 nmoles/10(6) cells and is elevated above levels found in monocytes obtained from patients either being treated with non-steroidal anti-inflammatory drugs (NSAIDs) (11.3 +/- 0.4 nmoles/10(6) cells; P < 0.01) or normal healthy volunteers (11.2 +/- 1.2 nmoles/10(6) cells; P < 0.01). A comparative study on glutathione (GSH) oxidation indicated that levels of monocyte GSH were elevated in myocrisin-treated patients (2.4 +/- 0.49 mmol/l) over normal healthy volunteers (0.83 +/- 0.18 mM; P < 0.01) and that levels of monocyte diglutathione (GSSG) were depressed (myocrisin, 0.97 +/- 0.41 micromol/l; normal, 5.71 +/- 0.73 micromol/l; P < 0.01). The non-inhibition of glutathione reductase and the inhibition of glutathione peroxidase by gold provides the link between these two observations. Thus, gold therapy would seem to elevate monocyte hydrogen peroxide, increase monocyte reduced glutathione and decrease plasma glutathione peroxidase activity. Subsequently, the data from this small group of patients (n = 10) provides an indication that, in-vivo, myocrisin contributes to an increase in oxidative stress.

A new ambulatory classification and funding model for radiation oncology: non-admitted patients in Victorian hospitals

The Victorian Department of Human Services has developed a classification and funding model for non-admitted radiation oncology patients. Agencies were previously funded on an historical cost input basis. For 1996-97, payments were made according to the new Non-admitted Radiation Oncology Classification System and include four key components. Fixed grants are based on Weighted Radiation Therapy Services targets for megavoltage courses, planning procedures (dosimetry and simulation) and consultations. The additional throughput pool covers additional Weighted Radiation Therapy Services once targets are reached, with access conditional on the utilisation of a minimum number of megavoltage fields by each hospital. Block grants cover specialised treatments, such as brachytherapy, allied health payments and other support services. Compensation grants were available to bring payments up to the level of the previous year. There is potential to provide incentives to promote best practice in Australia through linking appropriate practice to funding models. Key Australian and international developments should be monitored, including economic evaluation studies, classification and funding models, and the deliberations of the American College of Radiology, the American Society for Therapeutic Radiology and Oncology, the Trans-Tasman Radiation Oncology Group and the Council of Oncology Societies of Australia. National impact on clinical practice guidelines in Australia can be achieved through the Quality of Care and Health Outcomes Committee of the National Health and Medical Research Council.

Roxithromycin, clarithromycin, and azithromycin attenuate the injurious effects of bioactive phospholipids on human respiratory epithelium in vitro

The effects of the bioactive phospholipids (PL), platelet-activating factor (PAF), lyso-PAF, and lysophosphatidylcholine (LPC) on the beat frequency and structural integrity of human ciliated respiratory epithelium were studied in vitro, in the presence or absence of polymorphonuclear leukocytes (PMNL), the antimicrobial agents, roxithromycin, clarithromycin, and azithromycin and the antioxidative enzymes catalase and superoxide dismutase (SOD). All three PL caused dose-dependent slowing of ciliary beat frequency (CBF) and epithelial damage (ED) at concentrations > or = 1 microgram/ml, which were unaffected by inclusion of the antimicrobial agents and antioxidative enzymes. When epithelial strips were exposed to the combination of PMNL and PL, there was significant potentiation of ciliary dysfunction and ED, which was ameliorated by pretreatment of the PMNL with the antimicrobial agents or by inclusion of catalase, but not SOD. These results demonstrate that LPC, PAF, and lyso-PAF cause epithelial damage by direct mechanisms which are oxidant-independent, as well as by indirect mechanisms involving phagocyte-derived reactive oxidants. Macrolides and azalide antimicrobial agents may have beneficial effects on airway inflammation in asthma and microbial infections by protecting ciliated epithelium against oxidative damage inflicted by PL-sensitized phagocytes.

Carry-over effects of ozone on root growth and carbohydrate concentrations of ponderosa pine seedlings

Ozone exposure decreases belowground carbon allocation and root growth of plants; however, the extent to which these effects persist and the cumulative impact of ozone stress on plant growth are poorly understood. To evaluate the potential for plant compensation, we followed the progression of ozone effects, with particular emphasis on the development of new roots. Ponderosa pine (Pinus ponderosa Dougl. ex Laws.) seedlings were exposed to ozone for 2 years. Following removal of the seedlings from ozone, root growth was assessed to characterize the carry-over effects on new root production, and carbohydrate concentrations were measured to determine if allocation strategies differed among ozone treatments. Four months after removal from ozone, dormant seedlings had significantly lower starch concentrations in stems, coarse roots and fine roots than control seedlings. Following root flushing, starch concentrations in all seedlings decreased, with ozone-treated seedlings containing significantly less starch, sucrose, fructose, glucose and total monosaccharides than control seedlings. There was some evidence that stem starch was mobilized to compensate partially for the lower concentrations of root starch in ozone-treated seedlings; however, there was significantly less new root production in seedlings previously exposed to ozone for 2 years than in control seedlings. Early senescence of older needle age classes, perhaps resulting in inadequate available photosynthate, may be responsible for the reduction in new root production during the year following exposure to ozone. Stored carbohydrate reserves, which were depleted in seedlings previously exposed to ozone, were insufficient to compensate for the ozone-induced reduction in canopy photosynthate. We conclude that there are carry-over effects of ozone exposure on ponderosa pine seedlings, including an enhanced potential for seedling susceptibility to other stresses even in respite years when ozone concentrations are low.

Altered interleukin 12 and nitric oxide levels in recurrent miscarriage

The causes of recurrent miscarriage are not fully understood. Recent studies have suggested that whilst a TH 2 type immune response may be associated with a healthy pregnancy, miscarriage may be associated with a TH 1 type response. Serum levels of nitric oxide (NO) and Interleukin 12 (IL 12) were measured in; healthy non-pregnant women; healthy pregnant women; women suffering spontaneous abortion; pregnant women with a history of recurrent miscarriage; non-pregnant women with a history of recurrent miscarriage. Normal pregnancy was associated with a significant decrease in serum levels of nitrite (13.0 vs. 22.0 P < 0.0001). In women admitted with spontaneous abortion there was a significant increase in the levels of nitrite (16.0 vs. 13.0 P < 0.05), but no change in IL 12 compared to normal pregnant women. In pregnant women with a history of recurrent miscarriage levels of nitrite (16.0 vs. 13.0 P < 0.05) and IL 12 (10.0 vs. 6.0 P < 0.0006) were significantly elevated compared to normal pregnancy. When these women were sampled prior to becoming pregnant the levels of NO were found to be significantly lower than those in the non-pregnant control group (13.1 vs. 22.0 P < 0.05) although levels of IL 12 were unchanged. No correlation was found between serum nitrite and IL 12 levels. This report further supports the idea that polarisation of the immune response during pregnancy may predispose to recurrent miscarriage.

Organochlorine pesticides and polychlorinated biphenyls (PCBs) in sediments and biota from four US Arctic lakes

Organochlorine (OC) concentrations in surface sediment, snails (Lymnea sp.), and two freshwater fish species (grayling, Thymallus arcticus; and lake trout, Salvelinus namaycush) from four lakes in the US Arctic were determined. In surface sediment, chlorinated benzenes (including hexachlorobenzene, HCB), and p,p'-DDT were the primary analytes detected (max = 0.7 ng/g dry wt), while individual polychlorinated biphenyl (PCB) congeners were always below 0.1 ng/g. A wider range of compounds and higher concentrations were found in lake trout, the top predatory fish species in the same lakes. The concentration ranges for hexachlorocyclohexanes (HCHs), chlordane-related compounds (CHLORs), DDTs, and PCBs in lake trout and grayling were similar to those reported for other arctic freshwater fish (1-100 ng/g wet wt), but one to two orders of magnitude lower than Great Lakes salmonids. Nitrogen isotope analysis confirmed that differences in OC concentrations between grayling and lake trout are explained partly by differences in food web position.

Dietary restriction reduces insulin-like growth factor I levels, which modulates apoptosis, cell proliferation, and tumor progression in p53-deficient mice

Diet contributes to over one-third of cancer deaths in the Western world, yet the factors in the diet that influence cancer are not elucidated. A reduction in caloric intake dramatically slows cancer progression in rodents, and this may be a major contribution to dietary effects on cancer. Insulin-like growth factor I (IGF-I) is lowered during dietary restriction (DR) in both humans and rats. Because IGF-I modulates cell proliferation, apoptosis, and tumorigenesis, the mechanisms behind the protective effects of DR may depend on the reduction of this multifaceted growth factor. To test this hypothesis, IGF-I was restored during DR to ascertain if lowering of IGF-I was central to slowing bladder cancer progression during DR. Heterozygous p53-deficient mice received a bladder carcinogen, p-cresidine, to induce preneoplasia. After confirmation of bladder urothelial preneoplasia, the mice were divided into three groups: (a) ad libitum; (b) 20% DR; and (c) 20% DR plus IGF-I (IGF-I/DR). Serum IGF-I was lowered 24% by DR but was completely restored in the IGF-I/DR-treated mice using recombinant IGF-I administered via osmotic minipumps. Although tumor progression was decreased by DR, restoration of IGF-I serum levels in DR-treated mice increased the stage of the cancers. Furthermore, IGF-I modulated tumor progression independent of changes in body weight. Rates of apoptosis in the preneoplastic lesions were 10 times higher in DR-treated mice compared to those in IGF/DR- and ad libitum-treated mice. Administration of IGF-I to DR-treated mice also stimulated cell proliferation 6-fold in hyperplastic foci. In conclusion, DR lowered IGF-I levels, thereby favoring apoptosis over cell proliferation and ultimately slowing tumor progression. This is the first mechanistic study demonstrating that IGF-I supplementation abrogates the protective effect of DR on neoplastic progression.

Lung pathology in high-altitude pulmonary edema

Autopsy findings in 10 cases of high-altitude pulmonary edema have been collected from published articles and personal observations. All cases were males with a mean age of 37 years (22-62). The altitude of occurrence was from 8400 to 17 500 feet. The mean combined lung weight in nine cases was 1682 g (1200-3000 g). Cerebral edema was present in five of eight cases. The most frequency pulmonary findings in addition to diffuse edema consisted of leukocyte infiltrates, alveolar hemorrhages, thrombi in small pulmonary arteries, and alveolar hyaline membranes. Pulmonary infarction was present in only one case. Right ventricular dilatation was commonly present. The left ventricle was normal. No significant coronary disease was present.

Court-authorized medication for incompetent hospitalized patients

The authors provide an overview of recent developments affecting court-authorized treatment of incompetent patients, focusing on a state psychiatric system that has historically been in the vanguard in this arena in the United States.

Association mapping of disease loci, by use of a pooled DNA genomic screen

Genomic screening to map disease loci by association requires automation, pooling of DNA samples, and 3,000-6,000 highly polymorphic, evenly spaced microsatellite markers. Case-control samples can be used in an initial screen, followed by family-based data to confirm marker associations. Association mapping is relevant to genetic studies of complex diseases in which linkage analysis may be less effective and to cases in which multigenerational data are difficult to obtain, including rare or late-onset conditions and infectious diseases. The method can also be used effectively to follow up and confirm regions identified in linkage studies or to investigate candidate disease loci. Study designs can incorporate disease heterogeneity and interaction effects by appropriate subdivision of samples before screening. Here we report use of pooled DNA amplifications-the accurate determination of marker-disease associations for both case-control and nuclear family-based data-including application of correction methods for stutter artifact and preferential amplification. These issues, combined with a discussion of both statistical power and experimental design to define the necessary requirements for detecting of disease loci while virtually eliminating false positives, suggest the feasibility and efficiency of association mapping using pooled DNA screening.