Insulin secretion and intracellular Ca2+ rises in monolayer cultures of neonatal rat beta-cells

Glucose-induced insulin release, glucose-induced rises in intracellular free Ca2+ concentration ([Ca2+]i), and voltage-dependent Ca2+ channel activity were assessed in monolayer cultures of beta-cells from 3-5-day-old rats. The glucose-stimulated insulin secretory responses and [Ca2+]i rises were like those in adult rat beta-cells rather than fetal rat beta-cells. Voltage-dependent Ca2+ channel antagonists decreased glucose-induced insulin secretion, aborted the [Ca2+]i rise and, like deprivation of extracellular Ca2+, prevented the glucose-induced rise in [Ca2+]i when added before the glucose challenge. The presence of nifedipine-sensitive, voltage-dependent Ca2+ channels was demonstrated directly by measuring Ca2+ currents using the whole-cell configuration of the patch-clamp technique and indirectly by measuring [Ca2+]i after membrane depolarization by 45 mM K+ or 200 microM tolbutamide. Thus, in cultured beta-cells of 3-5-day-old rats the coupling of glucose stimulation to Ca2+ influx is essentially mature, in contrast to what has been reported for fetal or very early neonatal cells.

DNA primers for amplification of mitochondrial cytochrome c oxidase subunit I from diverse metazoan invertebrates

We describe "universal" DNA primers for polymerase chain reaction (PCR) amplification of a 710-bp fragment of the mitochondrial cytochrome c oxidase subunit I gene (COI) from 11 invertebrate phyla: Echinodermata, Mollusca, Annelida, Pogonophora, Arthropoda, Nemertinea, Echiura, Sipuncula, Platyhelminthes, Tardigrada, and Coelenterata, as well as the putative phylum Vestimentifera. Preliminary comparisons revealed that these COI primers generate informative sequences for phylogenetic analyses at the species and higher taxonomic levels.

Sexual practices and intentions among preadolescent and early adolescent low-income urban African-Americans

OBJECTIVE

To assess the sexual practices and the social and intrapersonal influences on sexual practices and intentions which have an impact on the risk for acquired immunodeficiency syndrome among pre- and early adolescent, low-income African-American youths.

DESIGN

Cross-sectional cohort study conducted in nine recreation centers serving three public housing developments in an eastern city.

PARTICIPANTS

Three hundred fifty-one African-American youths 9 to 15 years of age.

OUTCOME MEASURES

Past and intended sexual intercourse, and past and intended condom use determined by a risk assessment instrument delivered aurally and visually via a "talking" MacIntosh computer.

RESULTS

The median age was 11 years; 35% of youths had had sexual intercourse and 20% of virgins thought it likely that they would become sexually active in the next six months. Age and male gender were correlated with sexual activity. Of sexually active youths 62% had used a condom during their last episode of coitus and 60% expected to do so at the next episode. Among sexually active youths, 24% of boys and 35% of girls had had anal intercourse. Rates of foreplay (nonpenetrative sex) were low even among sexually active youths. The median number of sexual partners in the past six months was two. Social influences from parents, peers, and partners in an intimate relationship were important for all four sexual outcomes both by univariate analysis and after logistic regression.

IMPLICATIONS

A high percentage of the low-income, urban African-American pre- and early adolescents in this study are engaging or intending to engage in high-risk sexual behaviors. Acquired immunodeficiency syndrome reduction interventions for early adolescents should incorporate the importance of social influences from multiple sources.

Social influences on the sexual behavior of youth at risk for HIV exposure

OBJECTIVES

Adolescents are increasingly at risk for infection with human immunodeficiency virus (HIV) and other sexually transmitted diseases, especially in poor urban minority communities. To aid the design of interventions in these communities, this study investigated the role of knowledge, attitudes, perceived parental monitoring, and peer behavior in the onset and progression of sexual behavior in children at risk for exposure to HIV.

METHODS

A computerized personal interview was administered to 300 African-American 9- to 15-year-old children living in six public housing developments in a large US city.

RESULTS

Although children's knowledge about the hazards of sex increased with age, their sexual activity also increased (from 12% sexually experienced at 9 years of age to more than 80% experienced at 15 years of age). Parental monitoring appeared able to influence sexual activity. However, the perceived behavior of friends was associated with the rate at which sexual activity progressed with age and the degree to which condom use was maintained with age.

CONCLUSIONS

The early onset and prevalence of sexual behavior and the importance of peer group influence call for early interventions that simultaneously influence the parents and peers in children's social networks.

Functional imaging of head and neck tumors using positron emission tomography

Positron emission tomography (PET) is an imaging modality that generates in vivo maps of tissue radioactivity originating from a labelled substrate of glucose metabolism: 18-fluorine labelled deoxy-glucose (FDG). This study was undertaken to evaluate PET in the detection of head and neck malignancies, and to determine its effectiveness in diagnosing recurrent cancer in operated or irradiated fields. PET revealed that each biopsy-proven tumour is an area of increased radioactivity. Tumour radioactivity ranged from 130% to 300% above that of the cerebellum, and up to 650% above the contralateral, normal side. By basing the maps on tissue metabolic function, PET proved capable of distinguishing tumour (increased radioactivity) from scar tissue (reduced radioactivity). Its application may facilitate the diagnosis of recurrent tumours amid the fibrosis and distortion of normal architecture in operated, irradiated fields.

Changes in the cell wall accompanying drying and maturation determine the ease of isolation of protoplasts from wheat aleurone layers

Cell walls of aleurone tissue of developing wheat grains (25 days post anthesis) are degraded by cellulase to give a good yield of protoplasts. As grains become older the aleurone cell walls become increasingly resistant to cellulase, which is completely ineffective on 45-day old material. Resistance to cellulase is provoked even in aleurone cells of young grains by enforced drying of the grains to 12% water content. This suggests that the decreasing effectiveness of cellulase that occurs as grains develop and mature may be caused partly by the natural loss of water.Resistance to degradation by the aleurone cell walls of older or dried grains is to a large extent overcome by the addition of hemicellulase and xylanase to the digestion mixture but completely if acetyl esterase is also included. Changes involving hemicelluloses and xylans are therefore implicated in the effects of drying or maturation, including acetylation processes especially in grains which are almost mature. Arising from these findings a method has been developed for obtaining a high yield of protoplasts from aleurone layers of mature wheat grains, having a high viability and response to gibberellic acid.

Sexual abuse: developmental differences in children's behavior and self-perception

Developmental differences in behavior and self-perception were examined in a group of 44 preschool and school-age children referred for evaluation of sexual abuse and 41 comparison children with no history of sexual abuse, matched on age and gender, and from a similar socioeconomic background. Children suspected of having been sexually abused were rated by their parents as having more internalizing and externalizing problems than comparison children. When children rated their self-competence and social acceptance, there were no group differences between children based on their abuse status; however, there was significant within-group variation among the children suspected of having been sexually abused. Preschool children had elevated scores of perceived competence and social acceptance, and school-age children had depressed scores. There were no age differences among the children in the comparison group. The results suggest that among children suspected of abuse, not only does their self-perception vary by their developmental level, but preschool children may respond with elevated perceptions of themselves. Focusing on individual differences in children's response to suspicions of sexual abuse enables us to identify risk and protective factors that contribute to the psychological outcomes of child sexual abuse.

Operating characteristics of 18 different continuous-flow jet nebulizers with beclomethasone dipropionate liposome aerosol

A study of 18 different commercially available continuous-flow, jet nebulizers was performed with a standard liposomal formulation of beclomethasone dipropionate (Bec-DP) prepared with dilauroyl phosphatidylcholine (Bec-DLPC). The analysis compared the total Bec-DP output from aqueous suspensions of Bec-DLPC containing an initial starting reservoir concentration of 0.5 mg/ml. Aerosols from each nebulizer tested were characterized by the mass median aerodynamic diameter, geometric standard deviation, drug output, and the predicted percentage regional deposition of inhaled Bec-DLPC liposomes within the human respiratory tract. These data can provide a basis for the selection of commercially available jet nebulizers for use with glucocorticoid liposome aerosols for treatment of asthma and other inflammatory lung diseases.

A follow-up study of behavior problems associated with child sexual abuse

The objectives of this study were to examine: (a) behavior in children evaluated for sexual abuse, (b) the stability of their behavior over 4 months, and (c) the relationship between aspects of the abuse and the children's behavior. The Child Behavior Checklist (CBCL) was completed by parents of 93 prepubertal children evaluated for sexual abuse and 80 nonabused children matched on age, gender, and race. A follow-up CBCL was completed after 4 months by 45% of parents of abused children. Sexually abused children had significantly more behavior problems than comparison children, including depression, aggression, sleep and somatic complaints, hyperactivity, and sexual problems. At follow-up, only those children who initially had externalizing behavior in the clinical range improved significantly. During the initial evaluation, behavior problems were associated with the child's disclosure of abuse and during follow-up, behavior problems were associated with abnormal physical findings. However, behavior problems were not related to characteristics of the abuse or perpetrator, likelihood of abuse, or therapeutic services. The persistence of behavior problems suggests that children suspected of having been sexually abused should receive an assessment of their psychological status and careful follow-up.

Prenatal drug exposure: neurodevelopmental outcome and parenting environment

Examined neurodevelopmental patterns and caregiving environment among 20 infants prenatally exposed to cocaine and 20 drug-free infants. The Brazelton Scale was administered 4 times. Drug-exposed infants had less optimal neurodevelopment than comparison infants at birth, but by 6 weeks only differences in autonomic stability were apparent. Neurodevelopmental performance was related positively to the child-centered quality of the environment. Though support buffered stress in both groups, the effect was more robust among drug-free mothers. Findings support the need to consider neurodevelopmental recovery and the caregiving environment in evaluations of developmental outcome among drug-exposed infants.

Mycobacterial infections of the head and neck

Despite the decline of pulmonary tuberculosis in the Western world, the incidence of cervical mycobacterial infections has remained relatively unaffected. A retrospective review was conducted of 20 patients treated for head and neck tuberculosis from 1984 to 1991. They were mostly an immigrant group coming from underdeveloped countries close to the equator. All cases were treated with antituberculous chemotherapy; 18 patients also underwent surgical excision of their lymphadenopathy. Sixteen patients showed complete response to combined treatment and one relapse was successfully retreated with antituberculous medication. Three patients died from unrelated causes--two from human immunodeficiency virus infection and one from nasopharyngeal carcinoma. The most reliable indicator of mycobacterial infection was the pathologic specimen, making the need for surgical intervention an important diagnostic consideration. As with other reports, most patients in our series had negative chest x-ray films, variable responses to skin testing, and negative cultures. The epidemiology, pathogenesis, and management of this disease are discussed.

War and peace

Mary Black describes the superhuman effort required to evacuate patients from the shattered city of Sarajevo. But, she says, what its people really need is an end to the fighting.

Early initiation of sex and its lack of association with risk behaviors among adolescent African-Americans

OBJECTIVE

High rates of adolescent homicide, pregnancy, substance abuse, and sexually transmitted diseases underscore the importance of interventions designed to reduce problem behaviors. However, the definition of "problem" behavior and the association with other activities may change between youth cultures. Therefore, greater attention to defining the "problem" behaviors to be targeted will permit more effective utilization of primary vs secondary intervention strategies and identification of high-risk individuals.

DESIGN

Two studies of African-American adolescents regarding sexual intercourse, school truancy, substance abuse, and drug trafficking are presented. The first study involved 57 youths (10 to 14 years of age) from a pediatric primary health center and gathered data through pile-sorting. The second study of 300 youths (9 to 15 years of age) from six public housing sites used a questionnaire administered by a "talking" computer. Both studies assessed different self-reported behaviors, feelings about engaging in specific behaviors, and perceptions of friends' behaviors.

RESULTS

While 40% of subjects reported having had sex, substantially smaller proportions reported school truancy (14%), illicit drug use (2% to 6%), or drug trafficking (6%). Analyses of reported behaviors, feelings, and perceived peer norms revealed that sex was consistently depicted as forming a different domain from other problem behaviors.

CONCLUSIONS

Interventions that rely on primary prevention strategies for sexual intercourse and that identify sexually active youths as at risk for problem behaviors may not be appropriate for African-American adolescents growing up in resource-depleted urban areas.

A comparison of visual and automated methods of analyzing fetal heart rate tests

OBJECTIVES

Our objective in this study was to compare evaluation and clinical implications of visual versus computerized analysis of nonstress tests.

METHODS

Nonstress tests of 575 high-risk patients were analyzed visually and by a computer using the Oxford Sonicaid System 8000. Standard reactivity criteria were used for visual assessment; the System 8000 used an algorithm with the Dawes-Redman criteria.

RESULTS

Ninety-six percent of nonstress tests that met Dawes-Redman criteria were reactive by visual analysis; 93% of reactive nonstress tests met Dawes-Redman criteria. Only 30% of tests that failed Dawes-Redman criteria were nonreactive, whereas 44% of nonreactive tests failed to meet Dawes-Redman criteria. Sensitivities, specificities, and positive and negative predictive values were similar for both approaches. Additional tests or interventions would have occurred in 9% of the cases analyzed by System 8000 and in 49% of the cases analyzed visually.

CONCLUSIONS

Although these approaches rate nonstress tests differently, their diagnostic performances are similar. Automated fetal heart rate testing may become an acceptable alternative to conventional visual analysis.

Expression of the pro-opiomelanocortin gene in lung neuroendocrine tumours: in situ hybridization and immunohistochemical studies

Neuroendocrine tumours of the lung may be associated with the ectopic adrenocorticotrophin (ACTH) syndrome and may synthesize and secrete ACTH-related peptides in the absence of the syndrome. However, immunocytochemical analysis may not confirm these biochemical findings, particularly in small cell carcinoma, which is poorly granulated. To investigate further the morphological evidence for expression of the pro-opiomelanocortin (POMC) gene in neuroendocrine lung tumours, we have examined a series of 46 small cell carcinomas and 13 carcinoid tumours of the lung by in situ hybridization for POMC mRNA using a digoxigenin-labelled oligoprobe. We have compared the findings with the immunocytochemical detection of ACTH and beta-endorphin. In situ hybridization was positive in 15 of 46 small cell carcinomas (33 per cent) and in 8 of 13 carcinoid tumours (62 per cent). Immunocytochemical staining was positive in only one carcinoid tumour. These in situ hybridization studies have corroborated biochemical data indicating POMC gene expression in a high proportion of lung neuroendocrine tumours. This suggests that the low levels of expression detected by immunocytochemistry may be due to low levels of hormone storage. Multivariate analysis showed a weak negative association between POMC expression and survival in small cell carcinomas, although this did not reach statistical significance.

The diagnosis of child sexual abuse

OBJECTIVE

To examine how the history, psychological evaluation, medical examination, and child's response to the examination contributed to a diagnosis of child sexual abuse by an interdisciplinary team.

DESIGN

Patient series.

SETTING

Subspecialty clinic for evaluating prepubertal children alleged to have been sexually abused.

PARTICIPANTS

One hundred thirty-two children alleged to have been sexually abused and their parents or guardian, evaluated consecutively in a subspecialty clinic between September 1989 and June 1990.

MEASUREMENTS/MAIN RESULTS

A social worker interviewed the parents, a psychologist interviewed the child, and a pediatrician obtained a medical history and examined the child. Parents completed a Child Behavior Check list and the child's response to the physical examination was noted. Both a disclosure by the child and abnormal physical findings were significantly and independently associated with the team's diagnosis of sexual abuse, whereas the presence of sexualized behavior, somatic problems, and the child's response to the examination did not make an additional contribution to the diagnosis.

CONCLUSIONS

The findings support the need for a skilled psychological interview and a medical examination of a child alleged to have been sexually abused to make the diagnosis of sexual abuse. An interdisciplinary team appears to be a valuable approach for evaluating these children and their families.

Thyroid hormones precociously increase nerve growth factor gene expression in the submandibular gland of neonatal mice

The developmental regulation of the expression of nerve growth factor (NGF) was studied in the mouse submandibular gland (SMG). Having demonstrated that, in the neonatal mouse, maturation of the SMG can be accelerated by treatment with thyroid hormones, with the resulting induction in SMG content of NGF, studies were undertaken to further examine the locus of thyroid hormone action. Because of the sexual dimorphism of the SMG, both male and female neonatal mice were used. NGF messenger RNA levels were undetectable in SMGs from untreated immature mice, while hybridization to total RNA from T4-treated mice was easily observable for NGF complementary DNA. Treatment for 14 days compared to 7 days resulted in a 7-fold increase in SMG NGF mRNA levels. A signal was obtained in 21-day-old control mice using S1 nuclease protection analysis; T4 increased NGF mRNA levels by 100-fold in both male and female immature mice. Heteronuclear RNA levels were induced 20-fold by T4. No sex differences were readily observable. Determination of the effect of thyroid hormone treatment on SMG NGF gene expression by nuclear run-on assay demonstrated a significant transcriptional effect of T4. Initial experiments using the pmngf6 vector, which is a pBR322-derived probe containing the full length NGF cDNA, showed a 2.5-fold induction of gene transcription. When an internal fragment of pmngf6 was subcloned into pTZ18R, thus removing the dC/dG tails contained in pmngf6, the background hybridization was considerably reduced and a 12.5-fold induction in NGF gene transcription was obtained after T4 treatment of neonatal mice. The results show that thyroid hormones increase NGF gene expression in the SMG of the immature male and female mouse. This effect is due in part to a significantly enhanced rate of gene transcription.

Thyroid hormone and androgen regulation of nerve growth factor gene expression in the mouse submandibular gland

The nerve growth factor (NGF) content of the mouse submandibular gland (SMG) is under hormonal control and is modulated by both thyroid hormones (TH) and androgens. The sexual dimorphism of the gland is well documented. In the adult male mouse, the SMG contains 10 times more NGF compared to the female. Conversely, castration of male mice reduces the SMG NGF levels to those found in control females. In order to determine the locus at which androgens and TH exert their effect on NGF gene expression in the SMG, steady-state NGF mRNA levels were determined. Daily treatment of adult female mice with TH for 1 week increased NGF mRNA levels 6-fold. Androgen treatment produced a 20-fold increase in SMG NGF mRNA, which was comparable to levels detected in the control adult male SMG. The effect of TH on NGF mRNA levels was time-dependent and coincided with the increase in NGF protein concentrations. At 48 h after a single TH injection, NGF mRNA levels (measured in SMG total RNA) increased 2-4-fold, while heteronuclear (hn) RNA levels were increased 1.5-2-fold. The NGF gene transcription rate was determined by run-on assay following TH treatment. A small but significant 2-fold induction by TH of NGF gene transcription was found at 24-48 h. Cytoplasmic RNA prepared from the same SMGs used in the run-on experiments was tested by S1 nuclease protection; NGF cytoplasmic RNA was increased 7-fold in the SMGs of females treated with TH 48 h previously. These results demonstrate that the effect of TH on NGF gene expression is due in part to an induction of NGF gene transcription. The discrepancies observed between transcription rate and mRNA levels suggest that the major effect of TH is at the post-transcriptional level, possibly mRNA stabilization. The time required to observe an induction of TH on NGF gene transcription is suggestive of an indirect effect, possibly through the induction by TH of another protein which in turn activates the NGF gene.