Alpha and gamma motoneurons in the peroneal nuclei of the cat spinal cord: an ultrastructural study.

The aim of the present study was to investigate whether ultrastructural features can be used as a guide to identify alpha- and gamma-motoneurons among the intermediate-size neurons of the peroneal motor nuclei. The peroneus brevis and peroneus tertius muscles of adult cats were injected with horseradish peroxidase, and motoneurons labeled by retrograde axonal transport were examined by electron microscopy. In both nuclei, the distributions of cell-body diameters, measured in the light microscope, were bimodal covering the range of 28-84 microns, with a trough around 50 microns. The sample of 25 motoneurons selected for the ultrastructural study included not only large (presumed alpha) and small (presumed gamma) neurons but also intermediate-size cell bodies with diameters in the 40-60 microns range. For each motoneuron, 2-5 profiles were reconstructed from ultrathin sections taken at 6-8 microns intervals. Synaptic boutons were counted and their lengths of apposition were measured. On the basis of three criteria, namely: (1) bouton types present on the membrane, (2) percentage of membrane length covered by synapses, and (3) the aspect of the nucleolus, all the examined motoneurons, including those with intermediate sizes, fell into one of two categories. Fourteen motoneurons, with cell-body diameters in a range of 55-84 microns, were contacted by all types of boutons (mainly S-type with spherical vesicles, F-type with flattened vesicles, and C-type with subsynaptic cistern); the synaptic covering of the somatic membrane was over 40% and the nucleus contained a vacuolated nucleolus. These were considered alpha-motoneurons. Eleven motoneurons, with only S and F boutons, a synaptic covering under 30%, a compact nucleolus and a cell-body diameter ranging between 28 and 50 microns, were considered gamma-motoneurons. No other combination of the three criteria was observed. These results show that unequivocal distinction of alpha- and gamma-motoneurons is possible in the peroneal nuclei, on the basis of morphological differences independent of cell-body size.     

Chromosomes in tumors derived from mouse tumor x diploid cell hybrids obtained in vitro

Hybrids formed in vivo between Cl.1D tumor cells and host cells have been shown to carry a copy of each chromosome pair contributed by the host cell parent (1). However, in these hybrids, the tissue type of the host cell parents remained unknown. In the present study, hybrids between the malignant Cl.1D fibroblasts and either normal diploid fibroblasts (CF hybrids) or normal thymocytes (CT hybrids) were examined. These hybrids produced tumors when injected into host mice. Metaphases of growing hybrid cell tumors were analyzed. Neither CF nor CT malignant hybrids showed loss of any specific chromosome pair contributed by the normal cell parent. Since elimination of any chromosome pair contributed by the diploid fibroblast parent is not a prerequisite for CF hybrid tumoral growth, it seems unlikely that malignancy of hybrids results from nonexpression of normal alleles of those genes putatively implied in malignancy of Cl.1D cells.     

Distribution of fusimotor axons to intrafusal muscle fibres in cat tenuissimus spindles as determined by the glycogen-depletion method.

1. The distribution of fusimotor axons to bag1, bag2 and chain muscle fibres in cat tenuissimus spindles has been studied using a modification of the glycogen-depletion technique of Edstrrom & Kugelberg (1968). Single fusimotor axons were stimulated intermittently at 40-100/sec for long periods (30-90 sec) during blood occlusion. Portions of muscle containing the activated spindles were quick-frozen, fixed in absolute ethanol during freeze-substitution, and then embedded in paraffin wax. Serial transverse sections were stained for glycogen using the periodic acid-Schiff method, and examined for depletion. 2. Dynamic gamma axons (i.e. those that increase the dynamic index of primary-ending responses to ramp stretches of large amplitude) depleted bag1 fibres almost exclusively. 3. Static gamma axons (i.e. those that reduce or abolish the dynamic index) depleted both bag and chain fibres. Bag1 and bag2 fibres were depleted about equally. 4. A single static gamma axon may activate both bag and chain fibres in one spindle (the most common pattern), chain fibres only in another, and bag fibres only in a third spindle. 5. Static gamma axons with conduction velocities less than 25 m/sec also had a non-selective distribution, but no depletion was observed in bag2 fibres. 6. The zones of depletion produced by dynamic gamma axons were distributed more or less equally in the intra- and extracapsular parts of spindle poles, whereas those produced by static gamma axons were mainly intracapsular. 7. The results are compared with the glycogen-depletion studies of Brown & Butler (1973, 1975) and our own study of the distribution of static gamma axons to spindles in which all other motor axons had degenerated (Barker, Emonet-Dénand, Laporte, Proske & Stacey, 1973). The implications of the finding that both static gamma and dynamic gamma axons activate bag1 fibres are discussed.     

Glycogen-depletion method of intrafusal distribution of gamma-axons that increase sensitivity of spindle secondary endings

1. The glycogen-depletion method was used in cat tenuissimus muscles to investigate whether the action of static gamma-axons that increase the sensitivity of spindle secondary endings to muscle length is associated with a specific pattern of distribution of these axons to intrafusal muscle fibers. 2. In each experiment, a single gamma-axon acting on a secondary ending of a precisely located spindle was repetitively stimulated, and subsequently the intrafusal muscle fibers of that spindle were examined for glycogen depletion. 3. The gamma-axons whose repetitive stimulation increased the length sensitivity of secondary endings depleted all the chain fibers in one or both poles of the spindle, with the bag fibers being inconstantly involved. The gamma-axons whose stimulation did not exert this effect produced much more restricted patterns of glycogen depletion. 4. The length sensitivities of two secondary endings belonging to the same spindle were similarly affected by a single gamma-axon, whereas a gamma-axon could increase the sensitivity of a secondary ending without altering that of the primary ending of the same spindle. 5. The action exerted by single gamma-axons on secondary endings appears related to their intrafusal distribution since enhancement of the secondary endings sensitivity was observed only when all the chain fibers of at least one spindle pole were activated. 6. If several static gamma-axons supplying a given spindle are firing together, an increase in the length sensitivity of the secondary endings of that spindle can be expected since probably all chain fibers are activated.     

Intervention to reduce intentions to use tobacco among pediatric cancer survivors.

PURPOSE: In this randomized controlled trial, we sought to determine whether a risk counseling intervention would increase knowledge and perceived vulnerability to tobacco-related health risks and decrease future intentions to use tobacco among preadolescents and adolescents previously treated for cancer. PATIENT AND METHODS: Participants included 103 cancer survivors between the ages of 10 and 18 years who were randomly assigned to either a standard care control (SCC) group or a tobacco intervention (TI) group. Patients in the SCC group received standard advice about the risks of tobacco use. Patients in the TI group received more intensive late effects risk counseling in addition to an educational video, goal setting, written physician feedback, smoking literature, and follow-up telephone counseling. The effect of our intervention was assessed by self-reported knowledge, perceived vulnerability, and intentions at baseline, 6, and 12 months. RESULTS: Compared with the SCC group, patients who received our intervention had significantly higher knowledge scores, higher perceived vulnerability scores, and lower intention scores at 12 months. No significant differences between the SCC and TI groups at 6 months, across all measures, were found. CONCLUSION: Pediatric survivors' knowledge, perceived vulnerability to health risks, and intentions to use tobacco can be modified by a risk counseling intervention. The delayed effect of our intervention indicates that these changes may evolve over time. Implications for health care providers who engage in tobacco counseling with young cancer survivors are discussed. Additional longitudinal studies are needed to determine definitive long-term intervention effects on actual tobacco use in this high-risk population.     

Examination of the latent factor structure and construct validity of the stigma of suicide scale-short form

A major limitation of research on attitudes toward suicide is that most measures lack evidence of a stable factor structure. To investigate the structure of recently developed stigma of suicide scale-short form (SOSS-SF), we conducted an exploratory factor analysis in a sample of 499 undergraduates. Results revealed a three-factor structure: Stigma, Isolation/Depression, and Glorification/Normalization. We also identified good convergent and discriminant validity between the SOSS-SF and related constructs. In a separate sample of 570 undergraduates, a confirmatory factor analysis (CFA) demonstrated adequate fit for the three-factor model. In addition, a multiple-group CFA demonstrated invariance across gender.     

Enteral Autonomy with Teduglutide Treatment of Intestinal Failure/Short Bowel Syndrome with Depleted Central Venous Access

Digestive Diseases and Sciences -     

Hispanic Men in the United States: Acculturation and Recent Sexual Behaviors With Female Partners, 2006–2010

Objectives. We examined Hispanic men’s recent risky and protective sexual behaviors with female partners by acculturation.Methods. Using the 2006–2010 National Survey of Family Growth, we performed bivariate analyses to compare acculturation groups (Hispanic Spanish-speaking immigrants, Hispanic English-speaking immigrants, Hispanic US natives, and non-Hispanic White men) by demographics and recent sexual behaviors with women. Multivariable logistic regression models for sexual behaviors by acculturation group were adjusted for demographics.Results. Compared with Hispanic Spanish-speaking immigrants, non-Hispanic White men were less likely to report exchange of money or drugs for sex (adjusted odds ratio [AOR] = 0.3; 95% confidence interval [CI] = 0.1, 0.9), but were also less likely to report condom use at last vaginal (AOR = 0.6; 95% CI = 0.4, 0.8) and anal sex (AOR = 0.4; 95% CI = 0.3, 0.7). Hispanic US natives were less likely to report condom use at last vaginal sex than were Spanish-speaking immigrants (AOR = 0.6; 95% CI = 0.4, 0.8). English- and Spanish-speaking immigrants did not differ in risky or protective sexual behaviors.Conclusions. Our findings suggest that targeted interventions focusing on unique sexual risks and sociodemographic differences by acculturation level, particularly nativity, may be helpful for preventing sexually transmitted infections.In the United States, Hispanics are one of the subpopulations disproportionately affected by sexually transmitted infections (STIs).1 In 2010, reported cases of chlamydia were 2.7 times higher for Hispanics than for non-Hispanic Whites.1 Similarly, primary and secondary syphilis cases were 2.2 times higher for Hispanics than for non-Hispanic Whites, an increase of 9.5% since 2009.1 Reported gonorrhea rates were also 2.2 times higher for Hispanics than for non-Hispanic Whites. Regarding gender, the racial/ethnic disparity in gonorrhea rates was higher for men (48.7 per 100 000 for Hispanics vs 19.5 per 100 000 for non-Hispanic Whites) than for women (51.1 per 100 000 for Hispanics vs 26.6 per 100 000 for non-Hispanic Whites).1 Among young adult men (18–26 years), STI disparities were even greater; among Hispanic men, the prevalence of chlamydia and gonorrhea was 5.3 and 4.1 times higher than for non-Hispanic White men, respectively.2Research has shown that Hispanics face many unique challenges that increase their risks for STIs, including immigration-related challenges, living apart from their spouse or regular partner, language barriers, racism, social isolation, and limited access to health care.1,3–5 Compared with non-Hispanic Whites, Hispanics often also have higher poverty, unemployment, and high school dropout rates, and are younger.1,4,6 From 2000 to 2010, the Hispanic population in the United States increased by more than 15.2 million (an increase of 43%), contributing to half of the total population growth in the country.7 Because of the growing Hispanic population, the disproportionate burden of STIs, and the numerous barriers and challenges increasing their risk for STIs, an assessment of the sexual behaviors of Hispanics, including risk and protective behaviors, are of public health importance.An epidemiological concept known as the Hispanic paradox posits that health outcomes for Hispanics tend to be more similar to those of non-Hispanic Whites than those of non-Hispanic Blacks because of less acculturation, or “Americanization,” among Hispanics, which has been shown to be associated with lower sexual risk behaviors and better health outcomes.8–10 Some research suggests that the Hispanic paradox is variable and fluid or may not exist at all.11,12 Although many studies have examined the relationship between acculturation and sexual risk behaviors that are related to STI transmission, most of this research has focused on Hispanic women, adolescents, or men who have sex with men.13–22 Fewer studies have examined differences among Hispanic men in their sexual behaviors with female partners in terms of acculturation group. One study found that low-income, recent-immigrant Hispanic men (living in the United States less than 5 years) were more likely to commercially exchange sexual services and less likely to have a main sex partner than established immigrants (living in the United States for more than 5 years).23 Conversely, established Hispanic immigrant men were more likely to report unprotected sexual intercourse and multiple sex partners than recent immigrants.23 For protective behaviors, condom use at last sex did not significantly differ by acculturation among Hispanic men, although condom use is positively associated with acculturation for women.18,24,25 All of these studies were restricted to specific local areas.Acculturation of Hispanics has been measured in many ways—the use of a single variable, a combination of variables, or scales developed to capture the various aspects of acculturation. Complex measures of acculturation include attitudinal and behavioral factors focused on cultural values.10 More intricate scales of acculturation include heritage and mainstream scales with measures of attitude, behavior, and social relations.10,26 However, it is difficult to include comprehensive measures of acculturation in national surveys that have limited space and competing interests. Measures such as language, country of origin, nativity, and length of time in the country are considered proxy measures of acculturation.11,13,19,27–29 The most frequently used variable to measure acculturation is language of interview (English or Spanish) or the language spoken at home.3,13,14,17,19,21,22,24,27–33 Although acculturation is a multifaceted concept, research suggests that language preference may be a reliable proxy for more complex acculturation measures of Hispanics living in the United States.17For an examination of differences in Hispanic men’s sexual behaviors with female partners by level of acculturation, a national-level examination is useful given the diversity of the Hispanic population in the United States, where origin (Mexican, Puerto Rican, Cuban, Central American, etc.) differs by geography.34 Using data from a national survey, we analyzed the recent sexual behaviors of acculturation groups of Hispanic men (categorized by language of interview and nativity) and compared them with those of non-Hispanic White men. Specifically, we sought to examine differences in recent risky and protective sexual behaviors with female partners among acculturation groups using the 2006–2010 National Survey of Family Growth (NSFG).     

Pancreatic expression of human insulin gene in transgenic mice.

We have investigated the possibility of obtaining integration and expression of a native human gene in transgenic mice. An 11-kilobase (kb) human chromosomal DNA fragment including the insulin gene (1430 base pairs) was microinjected into fertilized mouse eggs. This fragment was present in the genomic DNA of several developing animals. One transgenic mouse and its progeny were analyzed for expression of the foreign gene. Synthesis and release of human insulin was revealed by detection of the human C-peptide in the plasma and urine. Human insulin mRNA was found in pancreas but not in other tissues. These findings indicate that the 11-kb human DNA fragment carries the sequences necessary for tissue-specific expression of the insulin gene and the human regulatory sequences react to homologous signals in the mouse.