Olfactory bulbectomy alters NMDA receptor levels in the rat prefrontal cortex

Olfactory bulbectomized (OBX) rats show a variety of behavioral and biochemical deficits that parallel human depression. We investigated the expression of glutamate receptor subtypes in cortical and subcortical brain regions following bilateral olfactory bulbectomy in adult rats. Quantitative receptor autoradiography using [(125)I]MK-801 (NMDA receptor), [(3)H]AMPA (AMPA receptor), and [(3)H]kainate (kainate receptor) was performed on brain sections at 1-5 weeks following olfactory bulbectomy. Our results show an elevation of NMDA receptors in the medial prefrontal cortex within 1 week following bulbectomy, which persisted up to at least 5 weeks post-bulbectomy. Neither kainate nor AMPA receptors were altered in any brain region examined. The potential significance of these results is discussed in light of experimental findings supporting a role for NMDA receptors in the mechanism of action of antidepressant drugs and the pathophysiology of major depression.

Enhanced nucleus accumbens dopamine and plasma corticosterone stress responses in adult rats with neonatal excitotoxic lesions to the medial prefrontal cortex

The medial prefrontal cortex modulates the nucleus accumbens dopamine response to stress and has been implicated in feedback regulation of hypothalamic-pituitary-adrenal axis activation by stress. Here we report on the effects of bilateral neonatal (postnatal day 7) ibotenate-induced lesions to the medial prefrontal cortex on nucleus accumbens dopamine and neuroendocrine function in adult rats. Voltammetry was used to monitor the dopamine response to each of five, once-daily exposures to tail-pinch stress whereas alterations in neuroendocrine function were determined from the plasma corticosterone response to a single 20-min episode of restraint stress. Potential lesion-induced deficits in sensory-motor gating were assessed by measuring prepulse inhibition of the acoustic startle response before and after repeated stress. Our data show that each daily stress episode elicited larger and longer-lasting dopamine increases in prefrontal cortex-lesioned animals than in sham-lesioned controls. Furthermore, greater stress-induced elevations in plasma corticosterone were seen in lesioned animals than in their sham-lesioned counterparts. However, while repeated stress potentiated startle responses in animals of both groups, there was no effect of lesion on the amplitude or on prepulse inhibition of the startle response.Together, these findings indicate that neonatal prefrontal cortex damage can lead to changes in mesolimbic dopamine and neuroendocrine function during adulthood. They also add to a growing body of experimental and clinical evidence implicating abnormal prefrontal cortex neuronal development in the pathophysiology of schizophrenia and other disorders linked to central dopamine dysfunction.

[Improvement in inspiratory muscle function in patients with mitral stenosis after percutaneous mitral valvuloplasty. Preliminary communication]

BACKGROUND

It has been proved that there is an inspiratory muscle dysfunction in mitral stenosis; Although its causes still remain unknown.

AIM

To evaluate the effect of percutaneous balloon mitral valvuloplasty (PMV) on inspiratory muscle performance (IMP) in patients with mitral stenosis (mitral area < 1.5 cm2).

PATIENTS AND METHODS

We studied IMP in 8 patients (35 +/- 10 years) before and 3 months after successful PMV. Inspiratory muscle strength was studied by measuring maximal statistical inspiratory mouth pressure (MIP). Endurance was evaluated using a two minute incremental threshold loading test in order to obtain the maximal sustainable inspiratory pressure (SIP), with the maximal sustainable load (MSL) the patients could sustain for 2 minutes.

RESULTS

Mitral valvuloplasty increased mean cardiac index from 3.1 +/- 0.3 to 4.15 +/- 0.3 l/min/m2 (p < 0.01), and significantly decreased mean pulmonary and capillary pressures. The MIP value(118 +/- 6 cmH2O), similar to that of normal group, increased to 137 +/- 7 cmH2O (p < 0.01). SIP and maximal sustainable load were 52 +/- 3 cmH2O and 294 +/- 29 g respectively, lower than normal subjects (p < 0.05). They increased after PMV to 80 +/- 3 cmH2O and 463 +/- 26 g respectively (p < 0.001).

CONCLUSIONS

PMV improved inspiratory muscle function in patients with severe mitral stenosis, probably secondary to a decrease work of breath and improvement of ventricular function.

The teaching of cultural issues in U.S. and Canadian medical schools

PURPOSE

Despite the importance of culture in health care and the rapid growth of ethnic diversity in the United States and Canada, little is known about the teaching of cultural issues in medical schools. The study goals, therefore, were to determine the number of U.S. and Canadian medical schools that have courses on cultural issues, and to examine the format, content, and timing of those courses.

METHOD

The authors contacted the deans of students and/ or directors of courses on cultural issues at all 126 U.S. and all 16 Canadian medical schools. Using a cross-sectional telephone survey, they asked whether each school had a course on cultural sensitivity or multicultural issues and, if so, whether it was separate or contained within a larger course, when in the curriculum the course was taught, and which ethnic groups the course addressed.

RESULTS

The response rates were 94% for both U.S. (118) and Canadian (15) schools. Very few schools (U.S. = 8%; and Canada = 0%) had separate courses specifically addressing cultural issues. Schools in both countries usually addressed cultural issues in one to three lectures as part of larger, mostly preclinical courses. Significantly more Canadian than U.S. schools provided no instruction on cultural issues (27% versus 8%; p = .04). Few schools taught about the specific cultural issues of the largest minority groups in their geographic areas: only 28% and 26% of U.S. schools taught about African American and Latino issues, respectively, and only two thirds of Canadian schools taught about either Asian or Native Canadian issues. Only 35% of U.S. schools addressed the cultural issues of the largest minority groups in their particular states.

CONCLUSIONS

Most U.S. and Canadian medical schools provide inadequate instruction about cultural issues, especially the specific cultural aspects of large minority groups.

Pediatricians' attitudes, beliefs, and practices regarding clinical practice guidelines: a national survey

BACKGROUND

Clinical practice guidelines are increasingly being used for a wide variety of medical conditions, but not enough is known about physicians' attitudes and beliefs about guidelines, how often and under what circumstances they are used, and factors associated with their acceptance.

OBJECTIVE

To determine practice guideline attitudes, beliefs, practices, and factors associated with use among a representative national sample of general pediatricians.

STUDY DESIGN

Cross-sectional mail survey.

SUBJECTS

Random sample of general pediatrician members of the American Academy of Pediatrics residing in all 50 states and Puerto Rico.

SURVEY INSTRUMENT

Twenty-four multiple-choice, Likert scale, yes-no, and open-ended questions about pediatric clinical practice guidelines.

RESULTS

From 1088 respondents, 461 specialists were excluded; the remaining 627 general pediatricians were mostly male (61%), white (81%), and in group practice (62%) in a suburban location (48%). Practice guidelines are used by 35% of pediatricians, in part by 44%, and not at all by 21%. Over 100 different practice guidelines are used, most commonly for asthma (77%), hyperbilirubinemia (27%), and otitis media (19%). Common reasons for use of practice guidelines include standardization of care (17%) and helpfulness (10%). Commonly cited problems with practice guidelines include failure to allow for clinical judgment (54%), use in litigation (16%), and limitation of autonomy (5%). In multivariate analysis, the odds of practice guideline use were greater among pediatricians in health maintenance organization practices (odds ratio [OR]: 9.1; 95% confidence interval [CI]: 1.2-68.0) and those who were nonwhite (OR: 2.3; 95% CI: 1.1-4.8), but lower in those with more weekly patient visits (OR:.7; 95% CI:.5-.9). Features most likely to lead to practice guideline use include simplicity (16%), feasibility (12%), and evidence of improved outcomes (10%). Most pediatricians agree that practice guidelines improve outcomes (89%), are motivated by a desire to improve quality (94%), and should not be used in litigation (82%) or disciplinary actions (77%), nor be motivated by a desire to reduce costs (73%).

CONCLUSIONS

Most general pediatricians use practice guidelines, but no specific guidelines, except those for asthma, are used by >27% of pediatricians. The results of this study suggest that practice guidelines are most likely to be followed if they are simple, flexible, rigorously tested, not used punitively, and are motivated by desires to improve quality, not reduce costs.

Dopamina: síntesis, liberación y receptores en el Sistema Nervioso Central

La dopamina es el neurotransmisor catecolaminérgico más importante del Sistema Nervioso Central (SNC) de los mamíferos y participa en la regulación de diversas funciones como la conducta motora, la emotividad y la afectividad así como en la comunicación neuroendócrina. La dopamina se sintetiza a partir del aminoácido L-tirosina y existen mecanismos que regulan de manera muy precisa su síntesis y liberación. Las técnicas de clonación molecular han permitido la identificación de 5 tipos de receptores dopaminérgicos, todos ellos acoplados a proteínas G y divididos en dos familias farmacológicas denominadas D1 y D2. Los receptores de la familia D1 (subtipos D1 y D5) están acoplados a proteínas Gs y estimulan la formación de AMPc como principal mecanismo de transducción de señales. Los subtipos pertenecientes a la familia D2 (D2, D3 y D4) inhiben la formación de AMPc, activan canales de K+ y reducen la entrada de iones de Ca2+ a través de canales dependientes del voltaje, efectos mediados también por proteínas G (Gαi y Gαo). Los receptores dopaminérgicos se encuentran ampliamente distribuidos en diversas áreas del SNC (aunque de manera diferencial de acuerdo al subtipo) donde son responsables de las diversas acciones fisiológicas de la dopamina. El estudio de los sistemas y receptores dopaminérgicos del SNC ha generado gran interés, debido a que diversas alteraciones en la transmisión dopaminérgica han sido relacionadas, directa o indirectamente, con transtornos severos como la enfermedad de Parkinson y la esquizofrenia, así como con la adicción a drogas (anfetaminas y cocaína por ejemplo).

Steroidal antiandrogens and 5alpha-reductase inhibitors

The purpose of this work is to synthesize a pregnane derivative with a high antiandrogenic effect or a high inhibitory activity for the enzyme 5 alpha-reductase type 2. Benign prostatic hyperplasia and prostate cancer are androgen dependent diseases which afflict a large percentage of the male population. Dihydrotestosterone 3, a 5 alpha-reductase metabolite of testosterone 2 has been implicated as a causative factor in the progression of these diseases, largely through the clinical evaluation of males who are genetically deficient of steroid 5 alpha-reductase enzyme. As a result of this study, the inhibition of this enzyme has become a pharmacological strategy for the design and synthesis of new drugs. The advent of finasteride 22 "figure 5" a 5 alpha-reductase inhibitor, has greatly alleviated the symptoms associated with benign prostatic hyperplasia. On the other hand, the discovery of cyproterone acetate 4 "figure 2" alone or in combination with the antiandrogens flutamide 14 "figure 3" or bicalutamide 21 has greatly reduced the misery of prostate cancer. Prostate cancer kills about 40,000 men in the USA and approximately 400,000 prostatectomies are performed each year. In our laboratory we have recently synthesized ten new progesterone derivatives 17 alpha-acyloyloxy-6-halo (chloro, bromo) 16 beta-methyl-4, 6-pregnadiene-3, 20-diones (54a-54e and 55a-55e), "figure 10". These steroids were evaluated as antiandrogens and exhibited a much higher activity than the commercially available cyproterone acetate 4. The same compounds were also evaluated as 5 alpha-reductase inhibitors and showed a slightly higher inhibitory activity than that of finasteride 22, the drug of choice today for the treatment of benign prostatic hyperplasia In another study we synthesized several new 4-halo (bromo and chloro) 17 alpha-benzoyloxy and also 4-halo-17 alpha-acetoxy progesterone derivatives (58-63) "figure 13". These compounds were prepared from the commercially available 17 alpha-acetoxy progesterone 56. The pharmacological evaluation of these steroids "figure 14" indicated that the 17 alpha-benzoyloxy derivatives (4-chloro and bromo) 62 and 63 were very potent antiandrogens. On the other hand, the 4-halo (bromo and chloro) 17 alpha-acetoxy (58, 59) and the 17 alpha-benzoyloxy-4-chloro analog 63 showed a very high inhibitory activity for the enzyme 5 alpha-reductase type 2 "figure 15".

Synthesis and pharmacological evaluation of 4-halo progesterone derivatives as antiandrogen

The pharmacological activity of eight pregnane derivatives 17-alpha acetoxyprogesterone 9, 17-alpha acetoxy-4, 5-epoxypregnan-3, 20-dione 10, 17-alpha acetoxy-4-chloro-4-pregnene-3, 20-dione 11, 17-alpha acetoxy-4-bromo-4-pregnene-3, 20-dione 12, 17-alpha hydroxy-4-bromo-4-pregnene-3, 20-dione 13, 4-chloro-17-alpha hydroxy-4-pregnene-3, 20-dione 14, 17-alpha benzoyloxy-4-bromo-4-pregnene-3, 20-dione 15 and 17-alpha benzoyloxy-4-chloro-4-pregnene-3, 20-dione 16 was determined. These compounds were evaluated as antiandrogens on gonadectomized hamster seminal vesicles. The pharmacological data in this study indicate that compounds 15 and 16 having a C-17 benzoyloxy moiety showed the highest antiandrogenic activity as measured by the reduction of the weight of the seminal vesicles, followed by the steroids 11 and 12 (17-alpha acetoxy group). The free alcohols 13 and 14 exhibited a lower antiandrogenic activity. Apparently, the ester moiety at C-17 is a necessary requirement for the presence of high antiandrogenic activity. Shows the inhibitory effect on the conversion of testosterone (T) to DHT, of the above described steroids as measured by the amount of produced DHT 2 expressed as pmoles of DHT/g of protein/h. Steroids 11, 12 and 16 showed a much higher inhibitory activity on the conversion of testosterone (T) to dihydrotestosterone (DHT) than presently used finasteride 3.

The impact of ethnicity, family income, and parental education on children's health and use of health services

OBJECTIVES

This study characterized ethnic disparities for children in demographics, health status, and use of services; explored whether ethnic subgroups (Puerto Rican, Cuban, and Mexican) have additional distinctive differences; and determined whether disparities are explained by differences in family income and parental education.

METHODS

Bivariate and multivariate analyses of data on 99,268 children from the 1989-91 National Health Interview Surveys were conducted.

RESULTS

Native American, Black, and Hispanic children are poorest (35%, 41% below poverty level vs 10% of Whites), least healthy (66%-74% in excellent or very good health vs 85% of Whites), and have the least well educated parents. Compared with Whites, non-White children average fewer doctor visits and are more likely to have excessive intervals between visits. Hispanic subgroup differences in demographics, health, and use of services equal or surpass differences among major ethnic groups. In multivariate analyses, almost all ethnic group disparities persisted after adjustment for family income, parental education, and other relevant covariates.

CONCLUSIONS

Major ethnic groups and subgroups of children differ strikingly in demographics, health, and use of services; subgroup differences are easily overlooked; and most disparities persist even after adjustment for family income and parental education.

Expression of dopamine receptors in the subthalamic nucleus of the rat: characterization using reverse transcriptase-polymerase chain reaction and autoradiography

We analysed the expression of dopamine receptor subtypes in the subthalamic nucleus by means of reverse transcriptase-polymerase chain reaction. We also studied, using autoradiography, all pharmacologically characterized dopamine receptors in four subregions of the subthalamic nucleus. For comparison, dopamine receptor subtypes were also evaluated in brain regions where they are more abundant and well characterized. The radioligands used were: [3H]SCH-23390, [3H]emonapride and [3H]2-dipropylamino-7-hydroxy-1,2,3,4-tetrahydronaphthalene for dopamine D1, D2 and D3 receptors, respectively; and [3H]YM-09151-2 in the presence of raclopride for dopamine D4 receptors. Finally, we also evaluated the effect of unilateral 6-hydroxydopamine injection into the medial forebrain bundle on dopamine receptor levels expressed in the ipsilateral subthalamic nucleus. The lesion was estimated by decrease in the binding of [3H]WIN-35428, a specific dopamine transporter label. D1, D2 and D3 receptor messenger RNAs and binding sites were present in the subthalamic nucleus, but no messenger RNA for D4 receptors was found, although specific binding sites for these receptors were observed. As compared to the intact side, the 6-hydroxydopamine lesion did not change D1 receptors, increased D2 receptors, and decreased D3 receptors and the dopamine transporter. The results suggest that postsynaptic D1, D2 or D3 receptors can mediate the effect of dopamine on subthalamic nucleus neuronal activity. D4 receptors would mediate exclusively presynaptic effects. These results reinforce the idea that dopamine receptors in the subthalamic nucleus may play an important role in the physiology of the basal ganglia and in the pathophysiology of Parkinson's disease.

Neonatal ventral hippocampal lesions attenuate the nucleus accumbens dopamine response to stress: an electrochemical study in the adult rat

Neonatal damage to the ventral hippocampus (VH) can lead, during adulthood, to behaviours that are believed to reflect enhanced mesocorticolimbic dopamine (DA) transmission. In the present study, the effects of neonatal excitotoxic lesions to the VH on spontaneous locomotor activity and stress-elicited increases in extracellular nucleus accumbens (NAcc) DA levels were examined in adult rats. Male pups received, on postnatal day 7, bilateral injections of either an ibotenic acid solution (lesioned) or vehicle (sham-lesioned) into the VH. At 3-4 months of age, animals were assessed during five daily sessions for changes in spontaneous locomotor activity associated with habituation to a novel environment. Voltammetry was used in separate groups of sham- and VH-lesioned animals to monitor the NAcc DA response to each of five once-daily exposures to tail-pinch stress. The results indicate that while VH-lesioned animals seem to habituate to novelty, they remain hyperactive relative to sham-lesioned controls. In contrast, however, stress consistently elicited in VH-lesioned animals smaller and shorter-lasting increases in NAcc DA than in sham-lesioned controls. These data suggest that neonatal excitotoxic damage to VH leads to changes in DA function that persist into adulthood. The blunted response to stress seen in VH-lesioned animals indicates that one consequence of such damage is a functional hyporeactivity in meso-NAcc DA neurons. The fact that these animals are spontaneously more active suggests compensatory changes in DA function that are efferent to DA terminals in NAcc.

Androgenic and anti-androgenic effects of progesterone derivatives with different halogens as substituents at the C-6 position

The pharmacological activities of four pregnane derivatives: 17alpha-hydroxy-16beta-methylpregna-4,6-diene-3,20-dio ne (7), 17alpha-acetoxy-16beta-methylpregna-4,6-diene-3,20-dio ne (8), 17alpha-acetoxy-6-bromo-16beta-methylpregna-4,6-diene- 3,20-dione (10), and 17alpha-acetoxy-6-chloro-16beta-methylpregna-4,6-diene -3,20-dione (11), were determined. The derivatives were evaluated on gonadectomized male hamster flank organs and seminal vesicles. The results indicate that topical applications of testosterone (T) on the flank organs increased the diameter of the pigmented spot. Similarly, the same phenomenon occurred on the glands treated with compound 11, whereas compound 10 decreased the size of the spot significantly. In this study, we determined the effects of several new steroids on the conversion of T to DHT in flank organs and seminal vesicles. The results show that compound 10 inhibited T conversion to DHT, but compound 11, at a dose of 200 microg, stimulated T conversion in both flank organs and seminal vesicles. However, when 2 mg of compound 11 was applied, it inhibited the conversion of T to DHT, suggesting that this compound also represses gonadotropin release. The difference between compounds 10 and 11 involves the electronegativity of the halogen at the C-6 position of the progesterone skeleton. These data clearly indicate that by decreasing the electronegativity of the halogen at C-6 (compound 10), 5alpha-reductase is inhibited in both tissues and at different pHs. On the other hand, when the electronegativity of the halogen atom was increased (11), there was a much lower inhibitory effect on the conversion of T to DHT.

Lewis and Fischer rats: a comparison of dopamine transporter and receptors levels

Previous reports have shown that the inbred strains of rat, Lewis (LEW) and Fischer 344 (F344), differ in several behavioural and biochemical indices of mesolimbic dopamine (DA) function. Specifically, these two strains differ in their behavioural and neurochemical response to novel environments, and acute amphetamine or cocaine challenge as well as in their susceptibility to addiction. To investigate if differences in DA D1-like, D2-like, D3 receptors and DA transporter could be correlated with these behavioural differences between strains, a comparative autoradiographic study of DA receptors and transporter within the striatal and accumbal regions was undertaken. We observed strain and region specific differences in binding levels for DA D2-like and D3 receptors and for the DA transporter. Namely, DA transporter levels in the striatum, nucleus accumbens and olfactory tubercle of LEW rats were significantly lower than in F344 rats. DA D3 densities in the shell of the nucleus accumbens and olfactory tubercle of LEW rats were lower than the levels found in the F344 rats. Finally, LEW rats have a lower levels of D2-like receptors in the striatum and the core of the nucleus accumbens compared to F344 rats. These data suggest that differences in DA transporter and DA receptors may in part contribute to differences in DA related behaviour seen between these two strains.

Non-Hodgkin's lymphomas in Mexico. A clinicopathological and molecular analysis

It is now well established that the clinical and histopathological characteristics of non-Hodgkin's lymphomas may vary significantly throughout the world. However, only a few reports have been published in Latin American countries. In this work, the clinical and pathologic findings of 264 patients with non-Hodgkin's lymphomas in Mexico City were analyzed. Diffuse large (14%) and diffuse mixed cell types (20%) predominated among nodal lymphomas. Within the group of patients with high grade malignancies, immunoblastic sarcomas were the most common (40/48). It is important to mention that follicular lymphomas were sporadic (4.5%). Among extranodal lymphomas the most commonly involved site was the gastrointestinal tract (11.3%), followed by the midline (6%). Molecular analysis of 65 cases with immunoglobulin and T-cell receptor gene probes showed that most lymphomas were of B-cell lineage (66%). The remaining group was composed of T-cell (25%) and bigenotypic malignancies (9%). All attempts to establish a correlation between the clinical stage and histopathological types with the genetic findings were not successful. However, pre-B and bigenotypic lymphomas were observed mainly in patients over 60 years of age. This study highlights some relevant characteristics of non-Hodgkin's lymphomas in Mexico.

Access barriers to health care for Latino children

BACKGROUND

Latinos will soon be the largest minority group in the United States, but too little is known about major access barriers to health care for this group and whether these barriers result in adverse consequences.

OBJECTIVE

To identify important access barriers to health care for Latino children, as cited by parents.

DESIGN

Cross-sectional survey of parents of all 203 children coming to the pediatric Latino clinic at an innercity hospital. Questions focused on barriers to health care experienced prior to receiving care at the Latino clinic.

RESULTS

Parental ethnicity included Dominican (36%), Puerto Rican (34%), Central American (13%), and South American (11%). Only 42% of parents were American citizens, whereas 36% had green cards, and 13% had no documentation. Eight percent of parents and 65% of the children were born in the United States. Parents rated their ability to speak English as follows: very well/well, 27%; not very well, 46%; and not at all, 26%. The median annual household income was $11,000; 40% of parents never graduated from high school, and 49% headed single-parent households. Forty-three percent of the children were uninsured. A sick child was routinely brought to hospital clinics by 56% of parents, to the emergency department by 21%, and to neighborhood health centers by 21%. When asked to name the single greatest barrier to health care for their children, parents cited language problems (26%), long waiting time at the physician's office (15%), no medical insurance (13%), and difficulty paying medical bills (7%). When parents were asked if a particular barrier had ever caused them not to bring their children in, transportation was cited by 21%; not being able to afford health care, 18%; excessive waiting time in the clinic, 17%; no health insurance, 16%; and lack of cultural understanding by staff, 11%. Some parents who spoke little or no English reported that medical staff not speaking Spanish had led to adverse health consequences for their children, including poor medical care (8%), misdiagnosis (6%), and prescription of inappropriate medications (5%). Multivariate analyses of selected health outcomes using 7 independent variables showed that low family income was significantly associated with greater odds of a child's having suboptimal health status (odds ratio, 1.5; 95% confidence interval, 1.04-2.2) and an increased number of physician visits in the past year (P<.04), but reduced odds (odds ratio, 0.6; 95% confidence interval, 0.4-0.9) of the child's being brought to the emergency department for a routine sick visit. Children whose parents had resided in the United States for fewer than 8 years were at reduced odds (odds ratio, 0.5; 95% confidence interval, 0.2-0.9) for having spent a day or more in bed for illness in the past year.

CONCLUSIONS

Parents identified language problems, cultural differences, poverty, lack of health insurance, transportation difficulties, and long waiting times as the major access barriers to health care for Latino children. Language problems can result in adverse health consequences for some children, including poor medical care, misdiagnosis, and inappropriate medication and hospitalization. Low family income is an important independent risk factor among Latino children for suboptimal health and high utilization of health services.

Serum insulin but not leptin is associated with spontaneous and growth hormone (GH)-releasing hormone-stimulated GH secretion in normal volunteers with and without weight loss

Weight loss in humans is associated with elevated hypothalamic-pituitary growth hormone (GH) secretion. This study evaluates the effects of weight loss on the hypothalamic-pituitary (GH-releasing hormone [GHRH]-GH) axis in 14 normal-weight (body mass index [BMI], 25+/-1 Kg/m2) subjects, of whom half had undergone a diet-induced weight loss of 14%+/-2% (mean+/-SEM). Insulin-like growth factor-1 (IGF-1), insulin, oral glucose tolerance, leptin, and GH pulse patterns were determined in both groups after weight maintenance for 1 week. Of note, we tested the effects of recent weight loss (3 months) and not a recent dietary intake, since both groups ingested a normal calorie diet for 2 days in the Clinical Research Center (CRC) prestudy. Serum insulin (3.8+/-0.7 v 9.0+/-0.9 microU/mL, P < .01) and C-peptide (0.44+/-0.06 v 0.59+/-0.04 ng/mL, P < .05) were significantly lower in the weight loss group. Serum leptin was not different. Endogenous GH pulse height (11.9+/-4.8 v 1.3+/-0.1 microg/L, P < .05), area per GH pulse ([AUC] 57+/-28 v 6+/-1 microg/L, P < .05), and mean GH (3.91+/-0.76 v 0.85+/-0.16 microg/L, P < .01) were increased in the weight loss group. The serum insulin level was inversely associated with the mean GH concentration (r=-.678, P < .01) and GH pulse height (r=-.733, P < .01). In addition to spontaneous GH secretion, the GHRH-stimulated GH pulse height (41.8+/-18.1 v7.1+/-1.6 microg/L, P < .05) and AUC (161+/-35 v46+/-13 microg/L/min, P < .05) were also increased in the weight loss group. The insulin concentration was also inversely correlated with the GHRH-stimulated GH pulse height (r=-.718, P < .01). The leptin concentration was correlated with the BMI (r=.554, P < .05) and body fat (r=.744, P < .01), but not with GH secretion. In summary, even though these patients were on a normal calorie diet, a history of recent weight loss in young men and women of normal weight and health can be associated with a significant increase in spontaneous GH pulse height and GHRH-stimulated pulse height. Weight loss was also associated with a reduced serum insulin level. The observed increase in GH secretion may be secondary to the reduction in insulin or alterations of other factors acting at the site of the pituitary.

[Isolation of Helicobacter pylori from dental plaque]

It has been suggested that oral dissemination might be the major transmission vehicle for Helicobacter pylori, and that dental plaque might act as its reservoir. The presence of H. pylori was investigated in 62 odontological male and female patients (average age: 35 years old). Samples were taken from supragingival plaque, placed in 0.3 ml of thioglycolate broth, cultured within 12 h in Mueller-Hinton agar with the addition of 5-7% of sheep blood and antibiotic supplement, and incubated at 37 degrees C in microaerophilia for 5-7 days. Typical colonies were identified by gram, urease, oxidase and catalase. H. pylori was detected in a 15 year-old patient suffering from gastric acidity (1.61% positivity index). The medium used facilitated recovery of the agent from a sample abundant in germs. H. pylori was not recovered from the same patient 12 months later, suggesting that there might have been a transitory passage by gastric reflux or that the bacterium was acquired from an exogenous source.

Barriers to health care access for Latino children: a review

BACKGROUND AND OBJECTIVES

More than 9 million Latino children currently live in the United States. Latinos will soon be the largest minority group in the country, but little is known about access barriers to health care faced by Latino children. We reviewed the literature to define specific barriers to care for Latino children, identify methodologic problems, and highlight the clinical and research implications of the identified barriers.

METHODS

We did a MEDLINE search, using combinations of the key words Hispanic, children, and access. Study exclusion criteria included "not an original research article," "enrolled only adult subjects," "no separate data analysis for children," and "dental care focus."

RESULTS

The search yielded 497 citations, of which 27 met the inclusion criteria. Of the 32 potential barriers identified, 21 had good supportive evidence. Lack of health insurance was a consistent barrier; recent data revealed that 26% of Latino children are uninsured, compared with 10% of white children and 14% of African-American children. Latino children also are at greater risk for episodic insurance coverage, low rates of private insurance, and loss of employee-based coverage. Parent beliefs about the etiology and treatment of their child's illness, use of home remedies, choice of sources of advice, and folk medicine practices may also influence how health care is obtained. Few data are available on differences in access among major Latino subpopulations, and no studies focused primarily on barriers as perceived by Latino parents. Evidence is equivocal or lacking that the following are barriers for Latino children: immigration status, duration of parent residency in the United States, and acculturation. Several barriers were identified that originate with practices and behaviors of health care providers, including reduced screening, missed vaccination opportunities, decreased likelihood of receiving prescriptions, and poor communication.

CONCLUSIONS

Lack of health insurance and lack of a regular source of care are major access barriers for Latino children, but many other barriers were identified that also can have a substantial effect on health care. In addition, the behaviors and practices of both health care providers and parents can affect access to care. Too little is known about what parents perceive to be the major barriers, access differences among Latino subpopulations, the roles of language and culture, and the causes of obstacles resulting from the actions of providers.

Molecular analysis of snRNAs and scRNAs using autoantibodies from patients with systemic lupus erythematosus

Immunoprecipitation analysis of total HeLa cells RNA extract by protein A-Sheparose purified autoantibodies and pCp 32P-3' end labeling RNAs revealed that U1, U2, U4 and U5 snRNAs are related with anti-Sm or U1nRNP autoantibodies, while the hY1, hY3, hY4 and hY5 scRNAs were related to anti-SSA/Ro autoantibodies present in sera of patients with Systemic Lupus Erythematosus. The authors detected molecular snRNAs and scRNAs specificities by autoantibodies in 71 sera, the molecular RNA specificity for anti-Sm (U1, U2, U4 and U5 snRNAs) was present in 39%; anti-SSA/Ro sera reacted against scRNAs (hY1, hY3, hY4 and hY5) in 36%, then anti-U1nRNP sera recognized U1 snRNA in 13% of sera and anti-rRNP related with rRNA were recognized in 8%. Twenty-nine SLE sera were RNA negative. A molecular characterization of the autoantibodies in sera from SLE patients may be a useful tool for clinical and laboratory diagnosis of SLE, and the use of autoantibodies as molecular probes allows to continue exploring some basic mechanism of gene expression.

Cloning and in situ hybridization analysis of the expression of polysialyltransferase mRNA in the developing and adult rat brain

Polysialyltransferase (PST) is an enzyme that catalyzes the addition of polysialic acid (PSA), a homopolymer of alpha-2,8-linked sialic acid residues, onto neural cell adhesion molecule (NCAM). The expression of PSA-NCAM in the brain is developmentally regulated and is of critical importance; however, the temporal and spatial developmental expression of brain PST, a potential key player in the control of PSA-NCAM levels, remains unclear. In the present study, we have cloned the coding region of rat PST cDNA by reverse transcription-polymerase chain reaction, using primers based on the hamster PST-1 cDNA sequence. A 39-mer oligonucleotide complementary to rat PST cDNA was synthesized to investigate the distribution of its mRNA in the developing and adult rat brain by Northern blot and in situ hybridization. In the embryonic rat brain, PST mRNA was detected abundantly throughout the neuroepithelia of most brain regions. At post-natal days 1 and 14, PST was detected throughout the neocortex, in the pyramidal cells (PC) of the hippocampus proper, the granule cell layer (GCL) of the dentate gyrus, the anterior ventral nucleus of the thalamus (AVNT) and the GCL and external germinal layer of the cerebellum. Finally, from PD21 until adulthood, expression of PST mRNA was restricted to the PC layer of the hippocampus proper, the GCL of the dentate gyrus, the AVNT, the GCL of the cerebellum and the dorsal and lateral nucleus of the anterior olfactory bulb. The developmental profile of PST mRNA is paralleled in some structures by that of the PSA-NCAM, there are, however, notable exceptions. Therefore, our results demonstrate that expression of rat PST mRNA is developmentally regulated, is present in the adult rat brain in restricted areas and may be involved in regulating temporal and spatial expression of PSA-NCAM.

Reciprocal interaction between glutamate and dopamine in the pars reticulata of the rat substantia nigra: a microdialysis study

We studied the interactions between glutamate and dopamine in the pars reticulata of the substantia nigra by using microdialysis in unanaesthetized rats. Increased extracellular levels of glutamate in the pars reticulata were obtained by microinjecting the muscarinic agonist carbachol into the ipsilateral subthalamic nucleus. The increase of glutamate levels was followed by increments in extracellular levels of dopamine and GABA. Increased levels of the three neurotransmitters were also observed during the administration of N-methyl-D-aspartate through the microdialysis probe. The increase in glutamate and GABA caused by N-methyl-D-aspartate was blocked by SCH 23390, a selective D1 antagonist. However, the D1 antagonist did not prevent the increase in dopamine levels. The selective D1 agonist SKF 38393, added to the microdialysis probe, increased the levels of the three neurotransmitters. However, after the lesion of the subthalamic nucleus with kainic acid, SKF 38393 increased only the level of GABA but not those of glutamate and dopamine. In addition, the lesion of the subthalamic nucleus produced a drastic (80%) fall in the extracellular levels of glutamate. These data suggest that glutamate, through N-methyl-d-aspartate receptors, stimulates the release of dopamine from dopaminergic dendrites present in the substantia nigra pars reticulata, and that dopamine in turn stimulates the release of glutamate and GABA. Both effects are mediated by D1 dopamine receptors present on subthalamonigral and striatonigral axon terminals, respectively.