Macromolecular diffusion of biological polymers measured by confocal fluorescence recovery after photobleaching

Fluorescence recovery after photobleaching with an unmodified confocal laser scanning microscope (confocal FRAP) was used to determine the diffusion properties of network forming biological macromolecules such as aggrecan. The technique was validated using fluorescein isothiocyanate (FITC)-labeled dextrans and proteins (molecular mass 4-2000 kDa) at 25 degrees C and with fluorescent microspheres (207 nm diameter) over a temperature range of 5-50 degrees C. Lateral diffusion coefficients (D) were independent of the focus position, and the degree and extent of bleach. The free diffusion coefficient (Do) of FITC-aggrecan determined by confocal FRAP was 4.25 +/- 0.6 x 10(-8) cm2 s-1, which is compatible with dynamic laser light scattering measurements. It appeared to be independent of concentration below 2.0 mg/ml, but at higher concentrations (2-20 mg/ml) the self-diffusion coefficient followed the function D = Do(e)(-Bc). The concentration at which the self-diffusion coefficient began to fall corresponded to the concentration predicted for domain overlap. Multimolecular aggregates of aggrecan ( approximately 30 monomers) had a much lower free diffusion coefficient (Do = 6.6 +/- 1.0 x 10(-9) cm2 s-1) but showed a decrease in mobility with concentration of a form similar to that of the monomer. The method provides a technique for investigating the macromolecular organization in glycan-rich networks at concentrations close to those found physiologically.     

Prevalence and impact of risk factors for lower body difficulty among Mexican Americans, African Americans, and whites

BACKGROUND: The purpose of the study was to estimate the prevalence of sociodemographic, health behavior, chronic disease, and impairment factors and their impact on difficulty in lower body function among two age-cohorts (51-61 and 71-81 years) of Mexican Americans, African Americans, and Whites. METHODS: Reports from 8,727 and 4,510 self-respondents of the 1992 baseline Health and Retirement Survey and the 1993 baseline Assets and Health Dynamics Study, respectively, were used to estimate prevalence. Multiple linear regression of the 4-item lower body difficulty scale (alpha = .80) was used to estimate the direct effects of the risk factors within the age-cohort and ethnicity groups. RESULTS: Overall, the risk factors are more prevalent among both minority groups and the older age-cohort. Lower body deficits are particularly high among Mexican Americans and the younger age-cohort of African Americans. The impact of risk factors does not vary much by ethnicity or age-cohort. Female gender, pain, arthritis, and heart and lung disease are the major risk factors, and they account for about one-third of the variance in lower body difficulty for each group. CONCLUSIONS: Efforts to prevent or reduce lower body difficulty should pay particular attention to pain, arthritis, and heart and lung disease. The central role of sociodemographic and behavioral factors in chronic disease argues for their continued inclusion in disability modeling and prevention.     

Radiobiological modeling of combined targeted 131I therapy and total body irradiation for treatment of disseminated tumors of differing radiosensitivity

PURPOSE: A model is presented for calculating combinations of targeted 131I and total body irradiation, followed by bone marrow rescue, in the treatment of tumors of different radiosensitivity. The model is used to evaluate the role of the total body irradiation component in the optimal combination regime as a function of the radiosensitivity of the tumor cells. METHODS AND MATERIALS: A microdosimetric model was used to calculate absorbed dose in small tumors and micrometastases when uniformly targeted by the radionuclide 131I. Cell kill was calculated from absorbed dose using an extended version of the linear quadratic model. The addition of varying total doses of total body irradiation, assuming 2 Gy fractions, was also calculated using the linear quadratic model. The net cell kill from combined modality (targeted 131I and total body irradiation) was computed for varying proportions of the two components, for a range of tumor sizes, restricting the total radiation dose to within tolerance for a full-course TBI regime (approximately 14 Gy total) in all cases. The calculations were repeated for a range of presumed tumor uptakes of the targeting agent and for a range of tumor radiosensitivities, typical of those reported for tumor cells of differing type in culture. Optimal regimes were identified as those predicted to yield a high probable tumor cure rate (evaluated using a Poisson statistical model) for all tumor sizes. RESULTS: The analysis supports earlier model studies which predicted that systemic combination treatment with targeted 131I and total body irradiation would be superior to either component used alone. The intrinsic tumor radiosensitivity is found to be a factor which influences the optimal combination of the 131I and external beam total body irradiation components. The total body irradiation component is greater in optimal regimes treating radio-resistant than radiosensitive tumors. However, an obligatory total body irradiation component is also predicted for more radiosensitive tumors; the analysis suggests that the total body irradiation component should in no circumstances be less than 2 x 2 Gy, whilst practical arguments exist in favor of higher doses. CONCLUSION: Total body irradiation is an obligatory component for effective systemic treatment of disseminated malignant tumors to which 131I can be selectively targeted. Clinical studies applying this strategy to the treatment of neuroblastoma by 131I targeted by meta-iodo-benguanidine (mIBG), total body irradiation and bone marrow rescue are now in progress.     

Alterations in the postovariectomy increases in gonadotropin secretion in middle-aged persistent-estrous rats: correlation with pituitary gonadotropin subunit gene expression

This study compared the changes in pituitary and serum levels of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) at various times following ovariectomy (OVX) between young cyclic and middle-aged persistent-estrous (PE) rats and related these to the relative gene expression of the pituitary gonadotropin subunits. In intact animals, both pituitary and serum levels of LH were similar between these two age groups, while the LH beta mRNA expression was significantly (p < 0.05) greater in young rats. Following OVX in young rats, the serum LH levels markedly increased (p < 0.05) beginning on day 7 and reaching a maximum fourfold increase by day 9. In contrast, the post-OVX increases in serum LH in middle-aged females were significantly delayed. OVX significantly (p < 0.05) increased pituitary LH contents of young rats by day 5, but had no effect on LH contents in middle-aged females until day 30 post-OVX. These changes were associated with increases in LH beta mRNA expression in both young and middle-aged females, but the levels were significantly (p < 0.05) lower in middle-aged females. Both pituitary and serum levels of FSH were significantly (p < 0.05) higher in middle-aged PE than in young rats prior to OVX, while the FSH beta mRNA expression was similar in both age groups. Following OVX in young rats, serum FSH levels rapidly increased (p < 0.05) on day 3 and attained tenfold higher values by day 30.(ABSTRACT TRUNCATED AT 250 WORDS)     

Teenage smoking, attempts to quit, and school performance

OBJECTIVES: This study examined the relationship between school performance, smoking, and quitting attempts among teenagers. METHODS: A logistic regression model was used to predict the probability of being a current smoker or a former smoker. Data were derived from the 1990 California Youth Tobacco Survey. RESULTS: Students' school performance was a key factor in predicting smoking and quitting attempts when other sociodemographic and family income factors were controlled. CONCLUSIONS: Developing academic or remedial classes designed to improve students' school performance may lead to a reduction in smoking rates among teenagers while simultaneously providing a human capital investment in their futures.     

Incident reporting in acute pain management

Incident reporting is an effective tool for continuous quality improvement in clinical practice. A prospective study on voluntary incident reporting in pain management was conducted at a major teaching hospital in Hong Kong. Over a 12-month period, 53 incidents were reported in 1275 patients who received pain relief treatments which were supervised by the acute pain service. The majority of the incidents were first detected by the pain team. The most common incidents involved delivery circuits, delivery pump and drug administration. A large proportion (81.4%) of the incidents were thought to be preventable. Human factors were involved in 41.9% of the patients reported, most commonly associated with unfamiliar technique/inexperience, inattention and inadequate communication. Four patients developed major morbidity of which two were attributed to inadequate analgesia, while three others had major physiological changes without morbidity. Strategies have been formulated to prevent further occurrence of these incidents. We propose that incident reporting is a potentially useful tool in identifying and preventing adverse events in postoperative pain management.     

Lidocaine as a diluent for administration of benzathine penicillin G

OBJECTIVE: Benzathine penicillin G is recommended for secondary prophylaxis of rheumatic fever. Its main disadvantage is local pain and discomfort associated with the injection. Lidocaine as a diluent may reduce this discomfort. We compared the administration of benzathine penicillin G with two diluents; sterile water and lidocaine hydrochloride 1% for penicillin concentrations and pain of injection. DESIGN: In a randomized double blind, crossover trial, 18 children ages 11 to 19 years who required prophylactic treatment for rheumatic fever were randomly divided into two groups. One received an injection of benzathine penicillin G diluted with 3.2 ml of sterile water, followed 1 month later by an injection of benzathine penicillin G diluted in lidocaine hydrochloride 1%; the second group received the same regimen in the reverse order. Serum penicillin concentrations and subjective pain sensation were determined after each injection. RESULTS: Peak serum penicillin concentrations at 24 h after injection were similar for both preparations (0.100 microg/ml for water, 0.102 microg/ml for lidocaine), as were the other serum values measured throughout the month. After 28 days detectable concentrations (> or =0.020 microg/ml) were found in 44 and 291% of the subjects, respectively (P = 0.4). Urine penicillin concentrations on Day 28 were 1.81 +/- 0.25 and 2.31 +/- 0.25 microg/ml, respectively. The pain score immediately after the injection was significantly lower with the lidocaine than with the sterile water dilution. CONCLUSION: Use of lidocaine hydrochloride as a diluent for benzathine penicillin G does not change the penicillin concentration in body fluids and significantly reduces the pain of injection. We suggest the use of lidocaine hydrochloride 1% as a diluent for benzathine penicillin G.     

In vivo effects of chicken interferon-gamma during infection with Eimeria

Newly hatched chickens are highly susceptible to infection by opportunistic pathogens during the first 1 or 2 weeks of life. The use of cytokines as therapeutic agents has been studied in animal models as well as in immunosuppressed patients. This approach has become more feasible in livestock animals, in particular poultry, with the recent cloning of cytokine genes and the development of new technologies, such as live delivery vectors. We have recently cloned the gene for chicken interferon-gamma (Ch-IFN-gamma). Poly-HIS-tagged recombinant Ch-IFN-gamma was expressed in Escherichia coli, was purified by Ni chromatography, and was found to be stable at 4 degrees C and an ambient temperature for at least several months and Several weeks, respectively. Ch-IFN-gamma was capable of protecting chick fibroblasts from undergoing virus-mediated lysis, induced nitrite secretion from chicken macrophages in vitro, and enhanced MHC class II expression on macrophages. Administration of recombinant Ch-IFN-gamma to chickens resulted in enhanced weight gain over a 12-day period. Furthermore, the therapeutic potential of Ch-IFN-gamma was assessed using a coccidial challenge model. Birds were treated with Ch-IFN-gamma or a diluent control and then infected with Eimeria acervulina. Infected birds treated with Ch-IFN-gamma showed improved weight gain relative to noninfected birds. The ability of Ch-IFN-gamma to enhance weight gain in the face of coccidial infection makes it an excellent candidate as a therapeutic agent.     

Attention deficit hyperactivity disorder (ADHD) is associated with early onset substance use disorders

We evaluated the association between attention deficit hyperactivity disorder (ADHD) and the age of onset of psychoactive substance use disorders (PSUD) in adults with ADHD. We hypothesized that ADHD and psychiatric comorbidity would be risk factors for early onset PSUD. We compared 120 referred adults having a clinical diagnosis of childhood-onset ADHD with 268 non-ADHD adults. All diagnoses were obtained using DSM-III-R based structured psychiatric interviews. We used group comparisons of age at onset and Cox proportional hazard models to examine the development of PSUD over time. ADHD was associated with earlier onset of PSUD independently of psychiatric comorbidity. Conduct and juvenile bipolar disorders conferred a significantly increased risk for early onset PSUD independently of ADHD. Psychiatric disorders commonly emerged before the onset of PSUD in both groups. Persistent ADHD with and without psychiatric comorbidity was associated with adolescent onset PSUD. In addition, comorbidity with conduct and juvenile bipolar disorders predicted very early onset PSUD in both ADHD and non-ADHD individuals. These findings confirm and extend previous findings documenting important associations between PSUD and psychiatric comorbidity including persistent ADHD.