Mechanisms of insulin resistance in cystic fibrosis

Cystic fibrosis (CF) is associated with a high incidence of diabetes. Studies evaluating causes of CF-related diabetes (CFRD) have consistently documented decreased insulin secretion. In patients with CFRD, insulin sensitivity has been documented to be decreased, but controversy exists in patients with normal or impaired glucose tolerance (IGT). We undertook this study 1) to reexplore insulin sensitivity in patients with IGT and 2) to evaluate potential mechanisms of insulin resistance in CF, including GLUT-4 translocation, elevation of serum cytokines, and free fatty acid (FFA) levels. We recruited nine CF subjects with impaired glucose tolerance (IGTCF) and nine age-, gender-, and body mass index-matched control volunteers. Each underwent a hyperinsulinemic euglycemic clamp (200 mU. m(-2). min(-1)) to measure insulin sensitivity. A muscle biopsy was obtained at maximal insulin stimulation for measure of GLUT-4 translocation with sucrose gradients. An oral glucose tolerance test and National Institutes of Health (NIH) clinical status scores were measured in all volunteers. We also measured tumor necrosis factor (TNF)-alpha levels and FFA in all subjects. Additionally, we report the results of TNF-alpha and FFA in 32 CF patients previously studied by our group. Results were that glucose disposal rate (GDR) was significantly lower in the CFIGT subjects than in controls, indicative of impaired insulin action. GLUT-4 translocation was impaired in CF and correlated with GDR. TNF-alpha levels were higher in all CF subjects than in controls and correlated with GDR. There was no difference in FFA between CF and control subjects. Modified NIH clinical status scores were inversely correlated with GDR and TNF-alpha levels. We conclude that IGTCF patients have decreased peripheral insulin sensitivity. Mechanisms include elevation of TNF-alpha and impaired translocation of GLUT-4.

Pharmacokinetics and tissue penetration of linezolid following multiple oral doses

The pharmacokinetics of multiple-dose linezolid were determined following administration of five 600-mg oral doses given every 12 h to each of six healthy male volunteers. Concentrations of the drug were determined in plasma and inflammatory blister fluid using high-pressure liquid chromatography. A mean peak concentration in plasma of 18.3 microg/ml (standard deviation [SD], 6.0) was attained at a mean time of 0.7 h (SD, 0.3) after the final dose. The penetration into the inflammatory fluid was 104% (SD, 20.7). A mean peak concentration of 16.4 microg/ml (SD, 10.6) was attained in the inflammatory fluid at 3 h (SD, 0.6) after the final dose. The elimination half-life from serum and inflammatory fluid was 4.9 (SD, 1.8) and 5.7 (SD, 1.7) h, respectively. The area under the concentration-time curve in plasma and blister fluid was 140.3 (SD, 73.1) and 155.3 (SD, 80.1) microg x h/ml, respectively. These data suggest that linezolid has good tissue penetration, and we can predict that it will be successful in the treatment of a variety of gram-positive infections.

Spontaneous urinary chemiluminescence and diet. An intervention study in humans

Spontaneous urinary visible chemiluminiscence has been measured in samples from a diet intervention study in humans. For a month, two groups, each of 21 male volunteers, received either a Mediterranean-type diet or an occidental (high-fat) diet. Urinary chemiluminescence levels (in 10(3) cpm) were 8.5 +/- 3.1 and 6.0 +/- 2.0 for the high-fat and Mediterranean-type diets, respectively. The differences obtained were statistically significant. These results reflect differences in the oxidative stress associate to both diets and support the proposal that spontaneous urinary chemiluminiscence constitutes a complementary index of systemic oxidative stress.

Immune responsiveness following academic stress in first-year medical students

Many studies illustrate that physical or psychologic stressors can alter human immune function, which might predispose one to an increased susceptibility to infections. In the present study, we monitored immune responsiveness in 16 first-year medical students (age 23.8 +/- 2.2 years) during the first examination session. Baseline blood samples were collected 30 days prior to the first examination session. Subsequently, subjects were randomly assigned to two groups, and blood samples were collected at 24 h (POST24h) or 48 h (POST48h) after an examination. The percentage of CD3(+), CD3(+)CD4(+), CD3(+)CD8(+), CD3(+)CD45RO(+), CD3(+)CD45RA(+), CD3(-)CD16(+)56(+), CD19(+), and CD14(+) cells in whole blood was examined to determine changes in circulating immune cell populations. Activation of peripheral blood mononuclear cells (PBMC) with a mixture of phorbol myristate acetate (PMA) and ionomycin or lipopolysaccharide (LPS) for 4 h was used to assess the distribution of interleukin-2 (IL-2)-secreting or interferon-gamma (IFN-gamma)-secreting CD4(+) and CD8(+) cells, as well as IL-1alpha-secreting CD14(+) cells. Activation with a combination of phytohemagglutinin (PHA) and LPS was used to assess secretion of IL-2, IFN-gamma, IL-4, IL-10, soluble IL-2 receptor-alpha (sIL-2Ralpha), IL-1beta, and IL-1R antagonist (IL-1Ra) by PBMC in 48-h cell culture. A significantly higher level of total T cells was found at POST24h, and CD14(+) was elevated at both POST24h and POST48h. The percentage of CD4(+) and CD8(+) cells significantly declined at POST24 and POST48h. A significant elevation in the percentage of memory T cells was observed at POST48h, whereas the percentage of naive T cells was elevated at POST24h and POST48h. These changes were accompanied by a significant decline in percentage of natural killer (NK) cells 24 h after the examination. The percentage of IL-2-producing CD4(+) and CD8(+) cells was significantly lower at POST24h, and the percentage of CD8(+)IFN-gamma(+) cells significantly declined at POST48h. The percentage of CD14(+)IL-1alpha(+) significantly declined at both POST24 and POST48h. A significant decrease was observed in IL-2 secretion 24 h after the examinations, and the secretion of IL-4 and IL-1beta significantly declined at POST48h. No changes in IFN-gamma, IL-10, sIL-2Ralpha, and IL-1Ra secretion were observed. We conclude that the stress outcomes of academic examinations in first-year medical students can significantly alter immune cell distribution and in vitro production and secretion of specific cytokines.

Increased activation of protein C, but lower plasma levels of free, activated protein C in uraemic patients: relationship with systemic inflammation and haemostatic activation

Chronic renal failure (CRF) courses with both systemic inflammatory reaction and haemostatic activation. We explored the relationship of these processes with plasma levels of free, activated protein C (APC) and complexes of APC with its inhibitors in patients with CRF under conservative treatment. Plasma concentrations of inflammatory cytokines [tumour necrosis factor alpha (TNFalpha) and interleukin 8], acute-phase proteins (C-reactive protein, fibrinogen, alpha1-anti-trypsin and von Willebrand factor), and markers of haemostatic activation (thrombin-anti-thrombin complexes, plasmin-anti-plasmin complexes, and fibrin and fibrinogen degradation products) were higher in patients than in controls. Inflammatory and haemostatic markers were significantly and positively correlated. Total plasma APC and APC:alpha1-anti-trypsin (alpha1AT) complexes were 44% and 75% higher in patients than in controls (P = 0.0001), whereas free APC was 20% lower (P < 0.015). No significant difference was observed in APC:protein C inhibitor (PCI) complexes between both groups. The free/total APC ratio was significantly lower in patients than in controls (P < 0.0001). Total plasma APC and APC:alpha1AT were positively correlated with activation markers of haemostasis and acute-phase proteins, whereas free APC was inversely correlated with plasma levels of creatinine, acute-phase proteins and fibrin degradation products (FnDP). Systemic inflammation and activation of haemostasis are interrelated processes in CRF. APC generation was increased in response to elevated thrombin production, but the inflammatory reaction, associated with increased synthesis of alpha1AT, reduced its anticoagulant effect. Lower free plasma APC in CRF may be pathogenically associated with atherothrombosis, a major cause of death in this disease.

Complementary effects of Mediterranean diet and moderate red wine intake on haemostatic cardiovascular risk factors

OBJECTIVES

To compare the effect of alcohol-free Mediterranean-type diet (MD) and high-fat diet (HFD) on plasma concentration of emergent haemostatic cardiovascular risk factors (HCVRF). Also, to test if red wine supplementation modifies HCVRF, independent of diet.

DESIGN, SUBJECTS AND INTERVENTION

Controlled prospective intervention study. Two groups, each of 21 healthy male university students (22+/-3.4 y), received either MD or HFD for 90 days. Between days 30 and 60, both diets were supplemented with 240 ml/day of red wine. Baseline and T30, T60 and T90-day samples were drawn. No drop out from the study was observed.

SETTING

University campus and outpatient nutrition clinic.

RESULTS

Volunteers on HFD at T30 had increases in pro-coagulants fibrinogen (22%), factor VIIc (9%), and factor VIIIc (4%), and decreases in natural anticoagulants antithrombin III (3%), protein C (11%) and protein S (6%) and of 20% in plasminogen activator inhibitor-1. At the same time, individuals on MD had increases in fibrinogen (4%), antithrombin III (5%), protein C (3%), protein S (2.7%), and decreases in factor VIIIc (9%), and plasminogen activator inhibitor-1 (21%). After adjusting by baseline values, MD was associated with lower plasma fibrinogen (P=0.03), factor VIIc (P=0.034) and factor VIIIc (P=0.0057) and with higher levels of protein S (P=0.013). Red wine supplementation, in both diets, resulted in decreased plasma fibrinogen (P=0.001) and factor VIIc (P=0.05), and increased tissue plasminogen activator antigen (P=0.01) and plasminogen activator inhibitor-1 antigen (P=0.0003). Wine consumption was also associated with significantly (P=0.01) divergent effects on antithrombin III: it decreased by 10% in individuals on HFD but increased slightly in those on MD. No effects of diet or wine were detected in plasma protein C and C-reactive protein.

CONCLUSION

MD and moderate consumption of red wine have complementary, mostly beneficial effects on HCVRF.

Effect of alpha subunit on allosteric modulation of ion channel function in stably expressed human recombinant gamma-aminobutyric acid(A) receptors determined using (36)Cl ion flux

Inhibitory gamma-aminobutyric acid (GABA)(A) receptors are subject to modulation at a variety of allosteric sites, with pharmacology dependent on receptor subunit combination. The influence of different alpha subunits in combination with beta3gamma2s was examined in stably expressed human recombinant GABA(A) receptors by measuring (36)Cl influx through the ion channel pore. Muscimol and GABA exhibited similar maximal efficacy at each receptor subtype, although muscimol was more potent, with responses blocked by picrotoxin and bicuculline. Receptors containing the alpha3 subunit exhibited slightly lower potency. The comparative pharmacology of a range of benzodiazepine site ligands was examined, revealing a range of intrinsic efficacies at different receptor subtypes. Of the diazepam-sensitive GABA(A) receptors (alpha1, alpha2, alpha3, alpha5), alpha5 showed the most divergence, being discriminated by zolpidem in terms of very low affinity, and CL218,872 and CGS9895 with different efficacies. Benzodiazepine potentiation at alpha3beta3gamma2s with nonselective agonist chlordiazepoxide was greater than at alpha1, alpha2, or alpha5 (P < 0.001). The presence of an alpha4 subunit conferred a unique pharmacological profile. The partial agonist bretazenil was the most efficacious benzodiazepine, despite lower alpha4 affinity, and FG8205 displayed similar efficacy. Most striking were the lack of affinity/efficacy for classical benzodiazepines and the relatively high efficacy of Ro15-1788 (53 +/- 12%), CGS8216 (56 +/- 6%), CGS9895 (65 +/- 6%), and the weak partial inverse agonist Ro15-4513 (87 +/- 5%). Each receptor subtype was modulated by pentobarbital, loreclezole, and 5alpha-pregnan-3alpha-ol-20-one, but the type of alpha subunit influenced the level of potentiation. The maximal pentobarbital response was significantly greater at alpha4beta3gamma2s (226 +/- 10% increase in the EC(20) response to GABA) than any other modulator. The rank order of potentiation for pregnanolone was alpha5 > alpha2 > alpha3 = alpha4 > alpha1, for loreclezole alpha1 = alpha2 = alpha3 > alpha5 > alpha4, and for pentobarbital alpha4 = alpha5 = alpha2 > alpha1 = alpha3.

Growth factors regulate the survival and fate of cells derived from human neurospheres

Cells isolated from the embryonic, neonatal, and adult rodent central nervous system divide in response to epidermal growth factor (EGF) and fibroblast growth factor 2 (FGF-2), while retaining the ability to differentiate into neurons and glia. These cultures can be grown in aggregates termed neurospheres, which contain a heterogeneous mix of both multipotent stem cells and more restricted progenitor populations. Neurospheres can also be generated from the embryonic human brain and in some cases have been expanded for extended periods of time in culture. However, the mechanisms controlling the number of neurons generated from human neurospheres are poorly understood. Here we show that maintaining cell-cell contact during the differentiation stage, in combination with growth factor administration, can increase the number of neurons generated under serum-free conditions from 8% to > 60%. Neurotrophic factors 3 and 4 (NT3, NT4) and platelet-derived growth factor (PDGF) were the most potent, and acted by increasing neuronal survival rather than inducing neuronal phenotype. Following differentiation, the neurons could survive dissociation and either replating or transplantation into the adult rat brain. This experimental system provides a practically limitless supply of enriched, non-genetically transformed neurons. These should be useful for both neuroactive drug screening in vitro and possibly cell therapy for neurodegenerative diseases.

[Study of cytokines kinetics in severe sepsis and its relationship with mortality and score of organic dysfunction]

BACKGROUND

The Infectious Systemic Inflammatory Response syndrome and multiple organic dysfunction have common physiopathological mechanisms. Multiple organic dysfunction can be assessed using severity scores.

AIM

To relate cytokine kinetics with a multiple organic dysfunction score during sepsis.

MATERIAL AND METHODS

Tumor necrosis factor alpha (TNF alpha) and interleukin 6 (IL6) kinetics were studied in 25 patients with severe sepsis with less than 48 h of evolution and interleukin 1 beta (IL beta) kinetics was studied in 13 patients. Measurements were made at 0, 12, 24 and 48 hours after admission to the study, using an ELISA technique. These parameters were correlated with the Marshall multiple organic dysfunction score and survival.

RESULTS

Mean age of study subjects was 70 years, the APACHE II score was 16.9 +/- 6 and the Marshall score was 6.8 +/- 3.6. Sepsis was of pulmonary origin in 56% of patients and intra abdominal in 32%. Mortality was 36%. TNF alpha increased during the study period (24.1 pg/ml initially and 37.8 pg/ml at 24 hours, with a slight posterior reduction, p < 0.02). These levels had no association with mortality or organic dysfunction. IL6 remained elevated during the first hours and had a tendency to decrease thereafter. Decreased patients had higher values than survivors (306 pg/ml and 55.4 pg/ml respectively, p = 0.011). Its values were tightly correlated with Marshall score, with the number of failing organs, with the presence of shock and with probability of dying during hospitalization. IL1 beta remained low and was not associated with clinical parameters.

CONCLUSIONS

There is a tight correlation between the elevation of IL6 and the severity of the Systemic Inflammatory Response and mortality in these patients with sepsis.

Pharmacokinetics and tissue penetration of gemifloxacin following a single oral dose

The pharmacokinetics and tissue penetration of gemifloxacin were determined during a 24 h period following oral administration of a single 320 mg dose to each of 10 healthy male volunteers. Concentrations of the drug in plasma, inflammatory blister fluid and urine were determined using a microbial assay. A peak plasma concentration (mean +/- S.D.) of 2.33 +/- 0.5 mg/L was reached at 1.20 +/- 0.4 h. Mean penetration into inflammatory fluid was 61.19 +/- 10.4%. A peak concentration of 0.74 +/- 0.3 mg/L was reached in the inflammatory fluid at a mean time of 3.40 +/- 1.7 h. The mean elimination half-life from serum and inflammatory fluid was 5.94 +/- 0.4 and 6.27 +/- 2.4 h, respectively. Urinary excretion of the drug at 24 h post-dose was 36.11% of the total given. These results demonstrate that gemifloxacin penetrates into the site of inflammation and reaches sufficient concentrations to inhibit many pathogens.

Sub-ice foraging behavior of emperor penguins

Emperor penguins (Aptenodytes forsteri) were equipped with a remote underwater video camera, the Crittercam, to evaluate sub-ice foraging behavior while the birds dived from an isolated dive hole. Three birds dived and foraged successfully for 1 h periods after being trained to wear and to dive with a harness for camera attachment. Video and depth profile recordings revealed that emperor penguins travel at shallow depths (&lt;50 m), ascend to the undersurface of the ice to feed on fish, and descend back to depth to return to the exit hole. Although the mean durations of dives of individual birds with the Crittercam were 21–35 % shorter than the diving durations of these same birds without the camera, the dive profiles in both situations were similar, thus demonstrating a similar foraging strategy in birds diving without the camera. Despite shorter diving durations with the camera, the penguins were still successful at prey capture in 80 % of 91 dives greater than 1 min in duration. Prey included the sub-ice fish Pagothenia borchgrevinki. Hunting ascents (from depth to within 5 m of the surface) occurred in 85 % of dives, ranged from zero to three per dive, and were associated with successful prey capture in 77 % of 128 ascents. Occasionally, several fish were captured during a single ascent. These observations and this application of video technology create a model for further physiological and behavioral studies of foraging, and also emphasize the potential importance of shallow dives as sources of food intake for emperor penguins during foraging trips to sea.

Lung cancer and arsenic concentrations in drinking water in Chile

Cities in northern Chile had arsenic concentrations of 860 microg/liter in drinking water in the period 1958-1970. Concentrations have since been reduced to 40 microg/liter. We investigated the relation between lung cancer and arsenic in drinking water in northern Chile in a case-control study involving patients diagnosed with lung cancer between 1994 and 1996 and frequency-matched hospital controls. The study identified 152 lung cancer cases and 419 controls. Participants were interviewed regarding drinking water sources, cigarette smoking, and other variables. Logistic regression analysis revealed a clear trend in lung cancer odds ratios and 95% confidence intervals (CIs) with increasing concentration of arsenic in drinking water, as follows: 1, 1.6 (95% CI = 0.5-5.3), 3.9 (95% CI = 1.2-12.3), 5.2 (95% CI = 2.3-11.7), and 8.9 (95% CI = 4.0-19.6), for arsenic concentrations ranging from less than 10 microg/liter to a 65-year average concentration of 200-400 microg/liter. There was evidence of synergy between cigarette smoking and ingestion of arsenic in drinking water; the odds ratio for lung cancer was 32.0 (95% CI = 7.2-198.0) among smokers exposed to more than 200 microg/liter of arsenic in drinking water (lifetime average) compared with nonsmokers exposed to less than 50 microg/liter. This study provides strong evidence that ingestion of inorganic arsenic is associated with human lung cancer.

[Number of physicians in Chile: current and prospective estimate, and an international comparison]

BACKGROUND

In the last decades, the number of Universities with medical schools has increased dramatically in our country.

AIM

To introduce a conceptual model to estimate the number of physicians that are incorporated to the profession in Chile every year as well as the cumulative number of active physicians in specific time frame. To provide information about the number of available physicians in the country and compare it with the international context.

MATERIAL AND METHODS

This model includes information about the number of students that are admitted in all medical schools of the country, the dropout rate, the number of immigrant physicians from other countries, and the cumulative number of active physicians in the previous period.

RESULTS

There is an increased number of new medical students starting in 1994 that will produce, starting in 2001, a significant increased in the number of new physicians graduated from Chilean Universities. Meanwhile the increased number of new physicians in recent years is mainly explained by a significant increase in immigrant physicians. The number of active physicians estimated by the year 2000 is 18,549 and this number will be 25,704 by the year 2007. With these estimated numbers, we introduce a qualitative model that allowed us to compare the current number of active physicians in Chile with other countries, especially those with a comparable degree of development. This model uses first The Human Development Index and later the per capita income of different countries adjusted by purchasing power in USA. According to these calculations, Chile has a lower number of physicians than similar countries, and this difference will persist, even after the significant increase in the new physicians expected for the new future.

CONCLUSIONS

Chile continues to have a lower number of physicians than countries with similar human development indices (Rev Méd Chile 2000; 128: 1167-76).

Linear discriminant models for unbalanced longitudinal data

This paper discusses statistical methods for the classification of observations into one of two or more groups based on longitudinal observations. Measurements on subjects in longitudinal medical studies are often collected at different times and on a different number of occasions. Classical multivariate methods for linear discriminant analysis are difficult to apply to repeated measurements due to the highly unbalanced structure observed in these data. Linear models for the analysis of longitudinal data proposed by Laird and Ware and non-linear models proposed by Lindstrom and Bates can be used to estimate population parameters for a discriminant model that classifies individuals into distinct predefined groups or populations. An example is presented using data from a study in 150 pregnant women in Santiago, Chile, in order to predict normal versus abnormal pregnancy outcomes.

[Academic performance of medical students: a predictable result?]

BACKGROUND

Traditionally, medical schools demand their students a high dedication in time, responsibility and integrity.

AIM

To assess the predictive capacity of several specific variables, on the academic performance of medical students.

MATERIAL AND METHODS

All students who entered during 1984-1995 period were studied. The academic performance was assessed using two indices: an overall evaluation of successfulness as determined by the approval rate in different courses and grade-point average obtained during the first three years at the Medical School. The variables used to predict academic performance were year of enrollment, high school grades, university admission test scores, biomedical and demographic characteristics. All these were measured at the time when the student was enrolled.

RESULTS

Eight hundred and eight students were studied at the end of the third year. The most important predictive variables selected for both performance indices were: high school grades, admission biology test scores, place were high school studies were done, and previous university studies. In addition verbal and mathematics admission academic performance tests scores were selected for grade-point average index. Although, the overall admission score and high school academic performance were significantly associated with the two outcomes, they were not selected in the final models.

CONCLUSIONS

The best predictors of an optimal academic performance in these medical students were high school grades, admission biology test scores, residing in Metropolitan Santiago and previous university studies.

Sedative but not anxiolytic properties of benzodiazepines are mediated by the GABA(A) receptor alpha1 subtype

Inhibitory neurotransmission in the brain is largely mediated by GABA(A) receptors. Potentiation of GABA receptor activation through an allosteric benzodiazepine (BZ) site produces the sedative, anxiolytic, muscle relaxant, anticonvulsant and cognition-impairing effects of clinically used BZs such as diazepam. We created genetically modified mice (alpha1 H101R) with a diazepam-insensitive alpha1 subtype and a selective BZ site ligand, L-838,417, to explore GABA(A) receptor subtypes mediating specific physiological effects. These two complimentary approaches revealed that the alpha1 subtype mediated the sedative, but not the anxiolytic effects of benzodiazepines. This finding suggests ways to improve anxiolytics and to develop drugs for other neurological disorders based on their specificity for GABA(A) receptor subtypes in distinct neuronal circuits.

In vitro activities of methylenecyclopropane analogues of nucleosides and their phosphoralaninate prodrugs against cytomegalovirus and other herpesvirus infections

Human cytomegalovirus (HCMV) infection does not generally cause problems in the immunocompetent adult but can result in severe clinical disease in the fetus, neonate, and immunocompromised host. Ganciclovir (GCV), the agent currently used to treat most HCMV infections, has resulted in much therapeutic success; however, efficacy remains suboptimal. Therefore, there is still a need to develop new compounds for use against HCMV infections. In the present study, several Z- and E-series methylenecyclopropane analogues and their phosphoroalaninate prodrugs were tested initially for activity against HCMV, strain AD169, and murine cytomegalovirus (MCMV) in vitro. Many were found to exhibit efficacy comparable to that of GCV against HCMV in plaque assays and were active against MCMV as well. The compounds were also tested for efficacy against herpes simplex virus types 1 and 2, varicella-zoster virus, and Epstein-Barr virus, and some had levels of activity that were comparable to that of acyclovir. In addition, the compounds synguanol (QYL-438) and 2-amino-6-cyclopropylamino analogue (QYL-769) were chosen for further evaluation and were found to be effective against additional laboratory and clinical isolates of HCMV and GCV-resistant isolates. QYL-438 and QYL-769 were found to be nontoxic in human and mouse fibroblasts and were considerably less toxic than GCV in granulocyte macrophage CFUs and erythroid burst-forming units. These results provide evidence for the high activity of some of these methylenecyclopropane analogues against various herpesviruses, particularly HCMV, in tissue culture and suggest that further evaluation is warranted to determine their potential for use in future clinical studies.

A clinical comparison of pain perception to the Wand and a traditional syringe

OBJECTIVES

This study compared the pain response of a group of 40 volunteers to the Wand with the response to syringe injections.

STUDY DESIGN

Of 240 total injections given, 120 were with the Wand system, and 120 were with the traditional aspirating syringe. Three injections were evaluated: injections to the middle superior alveolar (MSA) of the maxillary right first premolar and the maxillary left first premolar; palatal injections of the maxillary right first premolar and the maxillary left first premolar; and inferior alveolar nerve injection (IAN) of both the right and the left sides. Each volunteer received 6 injections, 3 on one side with the Wand and 3 on the opposite side with the syringe (control). All injections were given by the primary investigator without the use of a topical anesthetic. Pain perception levels were recorded with a 4-point visual analog scale: no pain, mild pain, moderate pain, and severe pain. The results were evaluated statistically by using an unpaired t test.

RESULTS

The results showed injections with the syringe were statistically more painful than injections with the Wand in 4 of 18 evaluations: MSA of the maxillary left first premolar, female volunteers responses to MSA of the maxillary left first premolar, IAN left side injections, and male responses to IAN left injections (P =.01, P =.05, P =.05 and P =.05, respectively).

CONCLUSIONS

The Wand generally seemed to provide less painful injections; however, the mean ratings of pain were mostly mild pain for both injections. Therefore, the clinical significance of the results should be interpreted with caution. The operator technique and tactile skill in syringe injections and site of injection (right or left) could be important factors that were not evaluated in this study.

Prevalence of the APC E1317Q variant in colorectal cancer patients

The notion that some common variants of APC might confer an increased colorectal tumour risk is supported by studies of the I1307K polymorphism. Recently it has been proposed that the E1317Q variant is also associated with an increased risk. We have studied the prevalence of E1317Q in 364 colorectal cancer patients and in 290 controls. Two patients were shown to possess E1317Q. Neither had a family history of colorectal cancer or co-existent adenomatous polyps. Two controls also carried E1317Q. This finding suggests that E1317Q is unlikely to be associated with anything more than a moderate increase in risk of colorectal cancer.

Tear lipocalins: potential lipid scavengers for the corneal surface

PURPOSE

To investigate the dynamic effect of tear lipocalins (TLs), the major lipid-binding protein in tears, at aqueous-cornea and lipid-aqueous interfaces, and their potential contribution to surface tension in the tear film.

METHODS

Human apo- and holo-TLs were applied to the aqueous subphase in a Langmuir trough, and changes in surface pressure were measured. Changes in the contact angle of tear components were observed on Teflon and ferric-stearate-treated surfaces. A nitroxide-labeled derivative of lauric acid and a fluorescence-labeled derivative of palmitic acid were used to monitor the dynamic interaction of lipid removed from a hydrophobic surface by the major tear components in solution.

RESULTS

TLs increase the surface pressure at the aqueous-air interface by penetrating, spreading, and rearranging on the surface. Apo-TLs show a longer diffusion-dependent induction time than holo-TLs due to more extensive oligomerization of the apoprotein. Kinetic analysis of relaxation time suggests that apo-TLs have more rapid surface penetration and rearrangement than holo-TLs, indicative of a more flexible structure in apo-TLs. TLs reduce the contact angle of solutions on lipid films, a property that is greater with TLs than other tear proteins. TLs, unlike lysozyme and lactoferrin, remove labeled lipids from hydrophobic surfaces and deliver them into solution.

CONCLUSIONS

TLs are potent lipid-binding proteins that increase the surface pressure of aqueous solutions while scavenging lipids from hydrophobic surfaces and delivering them to the aqueous phase of tears. These data suggest important functional roles for TLs in maintaining the integrity of the tear film.

Genetic characterization of heather (Calluna vulgaris (L.) hull) subject to different management regimes across great britain

Heather plants were collected from 34 populations in Great Britain, which differed according to their geographical location and associated management histories. Comparisons of differential grazing regimes were made across 10 sites in the first year of study, whereas the influence of differential burning regimes was considered at four sites during the second year. The extent of genetic variation, both within and between the selected heather populations, was examined using polymerase chain reaction (PCR)-based DNA fingerprinting methodologies. Initially, high genetic variation within populations obscured differences between populations. Heather stands that were geographically close proved to be genetically similar. Site latitude and longitude were strongly associated with genetic differences between heather populations; however, a range of grazing and burning management treatments had no consistent effect upon genetic diversity. The results represent the first national survey of genetic variation at the DNA level within UK populations of this important heathland species. They provided insights into the genetic structure of heather-dominated heathlands, revealing a lack of clonal dominance within populations, but rather a much more varied genetic makeup than might have been expected given the species' ability to propagate vegetatively. The processes that influence genetic diversity in heather populations are discussed, and the potential role of molecular techniques in heathland conservation is considered.