Determining the Aethalometer multiple scattering enhancement factor C from the filter loading parameter.

Light-absorbing aerosols heat the atmosphere; an accurate quantification of their absorption coefficient is mandatory. However, standard reference instruments (CAPS, MAAP, PAX, PTAAM) are not always available at each measuring site around the world. By integrating all previous published studies concerning the Aethalometers, the AE33 filter loading parameter, provided by the dual-spot algorithm, were used to determine the multiple scattering enhancement factor from the Aethalometer itself (hereinafter CAE) on an yearly and a monthly basis. The method was developed in Milan, where Aethalometer measurements were compared with MAAP data; the comparison showed a good agreement in terms of equivalent black carbon (R2 = 0.93; slope = 1.02 and a negligible intercept = 0.12 µg m-3) leading to a yearly experimental multiple scattering enhancement factor of 2.51 ± 0.04 (hereinafter CMAAP). On a yearly time base the CAE values obtained using the new approach was 2.52 ± 0.01, corresponding to the experimental one (CMAAP). Considering the seasonal behavior, higher experimental CMAAP and computed CAE values were found in summer (2.83 ± 0.12) whereas, the lower ones in winter/early-spring (2.37 ± 0.03), in agreement with the single scattering albedo behavior in the Po Valley. Overall, the agreement between the experimental CMAAP and CAE showed a root mean squared error (RMSE) of just 0.038 on the CMAAP prediction, characterized by a slope close to 1 (1.001 ± 0.178), a negligible intercept (-0.002 ± 0.455) and a high degree of correlation (R2 = 0.955). From an environmental point of view, the application of a dynamic (space/time) determination of CAE increases the accuracy of the aerosol heating rate (compared to applying a fixed C value) up to 16 % solely in Milan, and to 114 % when applied in the Arctic at 80°N.

Van-Gogh-like 2 antagonises the canonical WNT pathway and is methylated in colorectal cancers.

BACKGROUND: Aberrant activation of the canonical WNT signaling is a feature of colorectal cancer (CRC). Van-Gogh-like 2 (VANGL2) belongs to the non-canonical WNT pathway whose activation inhibits canonical WNT signaling. In this study, we investigated the role of VANGL2 and its epigenetic regulation in CRC. METHODS: Van-Gogh-like 2 expression and promoter methylation after 5-aza-2'-deoxycytidine (5-aza) treatment were evaluated in CRC cells. DNA samples from 418 sporadic CRCs were tested for VANGL2 promoter methylation and microsatellite instability (MSI). Proliferation, colony formation and activation of the WNT pathway were tested in cells after VANGL2 overexpression. RESULTS: Van-Gogh-like 2 mRNA was significantly higher in 5-aza-treated RKO, LOVO and SW48, whereas no differences were found in SW480. Van-Gogh-like 2 was fully methylated in RKO, SW48, HCT116, DLD1 and Caco2; partially methylated in LOVO, LS174T and SW837; and unmethylated in SW480, SW620 and HT29. Higher expression of VANGL2 mRNA was found in the unmethylated cell lines. In CRC specimens (8.93% MSI), methylated VANGL2 was associated with MSI, higher grade, proximal colon location and BRAF mutation. Van-Gogh-like 2 overexpression in SW480 significantly decreased proliferation, colony formation and ß-catenin levels. CONCLUSION: Van-Gogh-like 2 is frequently methylated in MSI-CRCs with BRAF mutation and may act as a tumour suppressor gene, counteracting WNT/ß-catenin signaling.

"Purple Drank" (Codeine and Promethazine Cough Syrup): A Systematic Review of a Social Phenomenon with Medical Implications.

In the early 1990s, several studies reported the misuse of codeine and promethazine hydrochloride cough syrup. Since then, the combination of this pharmaceutical, together with sprite or alcohol, known on the streets as "purple drank" or "lean", has become a popular drug among rap singers who promote its tranquilizing and euphoric effects through their music and videos. This review examines the "purple drank" phenomenon, taking into consideration its clinical and social implications. The study was conducted using PubMed, Scopus, and Web of Science as search engines, applying several inclusion and exclusion criteria and the string "Purple AND drank", resulting in 138 records. Seven papers that met our criteria were found. The risk of bias assessment, when applicable, was also considered, resulting in a low level of risk. Epidemiological data highlighted a heterogeneous diffusion of the misuse of this mixture, which is not exclusively linked to a specific type of user (African-American teenagers, athletes, and rappers), as previously reported in American newspapers and in the social media. New digital tools should be taken into consideration for further social and medical evaluations of this phenomenon.

Motion Index: a new parameter to evaluate the diastole by M-Mode imaging.

AIM: Heart failure with normal left ventricle (LV) ejection fraction is commonly understood as diastolic heart failure because this expression implies the presence of LV diastolic dysfunction diagnosed by specific echocardiographic findings, such as slow LV relaxation and increased LV stiffness. In this work the authors propose a new parameter named Motion Index, which is measurable by M-Mode technique and it is likely linked to diastolic dysfunction. METHODS: A patient population composed by 134 subjects was enrolled. They all were in New York Heart Association (NYHA) functional class II. Echocardiogram carried out in all patients allowed the authors to distinguish 2 patient arms depending on the presence or absence of diastolic dysfunction, evaluated by flow Doppler and tissue Doppler. RESULTS: After carrying out every echocardiographic examination, the authors also measured the new parameter that called Motion Index, and found that it had an average value of 46 in patients with normal diastolic function and 33.5 in patients with diastolic dysfunction. This parameter did not depend on systolic dysfunction. CONCLUSIONS: Data obtained showed a statistically significant correlation between Motion Index and means of diastolic function assessed by both flow and tissue Doppler.

Survey of Campylobacter jejuni in stray cats in southern Italy.

AIM: To evaluate the presence of thermotolerant Campylobacter spp. in stray cats in southern Italy. METHODS AND RESULTS: One hundred and thirteen animals were trapped in two different environments (urban area, harbour area) of the city of Naples. From each cat, rectal swabs were collected. The samples were processed in order to detect thermotolerant Campylobacter spp. by culture methods. The positive samples were then confirmed by multiplex polymerase chain reaction. Campylobacter jejuni was isolated from 19/113 (16.8%) stray cats, whereas Campylobacter coli was not isolated. The cat data (age, environment and sex) were analysed by two statistical analyses using the C. jejuni status (positive/negative) as a dependent variable. As regards statistical regression model results, age and environment were risk factors for C. jejuni positivity. In particular, cats older than 1 year had a significantly higher risk of being positive for C. jejuni than cats aged up to 1 year (OR = 10.440; P = 0.000). Moreover, cats living in the harbour area had a significantly higher risk to be a carrier of C. jejuni than cats living in urban area (OR = 17.911; P = 0.008). CONCLUSION: The findings of the present survey confirm stray cats as potential carriers of C. jejuni. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study on the prevalence of C. jejuni in stray cats in Europe.

The long QT syndrome in pediatric age: prognosis and risk factor.

AIM: Long QT syndrome is a rare arrhythmic disease with a low incidence in the general population. There are no sure clinical or electrocardiographic parameters that could lead to a correct prognostic stratification in patients affected by this syndrome. The correlation between the incidence of a sudden death or dangerous ventricular arrhythmias and the duration of QTc interval is still a controversial topic. METHODS: Twenty nine children affected by QT long syndrome were admitted to the Division of Pediatric Cardiology of the Casa del Sole Hospital of Palermo (Italy). Their diagnosis was made by electrocardiogram (ECG). The average age of the patients was 7.6 years. The average follow-up was 4 years and three months. A therapy with beta-blocker was administered to all the children. During the follow-up of 4 year and three months, patients were genotyped. Twenty-three out of 29 children had at least one relative affected by the syndrome. Three of them had a familiar dead because of this syndrome and everyone had a duration of maximum QTc higher than the cut off (P=0.0002). All the people who died had not followed the therapy with beta-blocker. Patients with a maximum QTc recorded <500 had not familiar death by this syndrome. RESULTS: Holter and echocardiogram recorded periodically during the observation did not show dangerous arrhythmic events. All children maintained a good health during the follow-up. CONCLUSION: Although conducted on a small study population, the data analysis recorded during this study suggests that in patients affected by QT long syndrome younger than 16 years old undergoing a beta-blocker therapy the prognosis is excellent. The duration of QTc interval appears as a negative prognostic factor, although the beta-blocker therapy has been reduced considerably the incidence of sudden death.

[Influence of mode of delivery in term breech presentation on the Apgar score and transfer in neonatal care unit. Results of the management of 568 singleton pregnancies in a level III French maternity]. / Influence de la voie d'accouchement dans la présentation du siège à terme sur le score d'Apgar et les transferts en néonatologie. Résultats de la prise en charge de 568 grossesses singleton dans une maternité française de niveau III.

OBJECTIVES: The aim of our study was to define the influence of mode of delivery in term breech presentation on the Apgar score and transfert in neonatal care unit using our university hospital protocol. MATERIAL AND METHOD: We conducted a retrospective study. The study included 568 singleton term pregnancies during the period January 1996 to December 2005. The main selection criteria were Apgar score and transfert in neonatal care unit. RESULTS: Analysis of the Apgar scores at 1.5 and 10min and transfer in neonatal care unit do not show any statistical difference. CONCLUSION: The absence of a difference in neonatal prognosis is to allow vaginal delivery to be carried out. To carry on with the teaching of obstetrical manoeuvres makes it possible to avoid pointless surgical intervention and a bad maternofoetal prognosis in the event of an unexpected breech presentation.

Glucose production in pregnant women at term gestation. Sources of glucose for human fetus.

The effects of pregnancy and diabetes on systemic glucose production rates and the sources of glucose for the human fetus in utero were evaluated in five normal, four gestationally diabetic, and one insulin-dependent diabetic subject undergoing elective caesarean section at term gestation. Five normal nonpregnant women were studied for comparison. Systemic glucose production rates were measured with stable tracer [1-(13)C]glucose according to the prime-constant rate infusion technique. Even though the plasma glucose concentration during normal pregnancy had declined as compared with the nonpregnant subjects (P < 0.0005), the systemic glucose production rate was 16% greater, a rate sufficient to provide the glucose requirement of the fetus at term gestation. The decline in glucose concentration could be the result of an increase in apparent volume of distribution of glucose. Systemic glucose production rates in well-controlled, gestationally diabetic subjects were similar to those in normal pregnant subjects (2.07+/-0.53 vs. 2.42+/-0.51 mg/kg.min). The sources of glucose for the human fetus at term gestation were evaluated by comparing (a) natural variation in (13)C:(12)C ratio of plasma glucose and (b) enriched (13)C:(12)C ratio of plasma glucose during [1-(13)C]glucose infusion in maternal and fetal blood at delivery in both normal and diabetic subjects. These data showed that the fetal glucose pool was in equilibrium with the maternal glucose pool in both normal and diabetic subjects, indicating that a brief maternal fast did not initiate systemic glucose production in human fetus. A materno-fetal gradient was observed for betahydroxybutyrate.

[Minors' request for voluntary termination of pregnancy. A study of their motivations and influences at the CHU of Nice]. / Demandes d'IVG des mineures. Etude de leurs motivations et influences menée au CHU de Nice.

OBJECTIVE: The goal of this work was to determine the influences exerted on minors during a request for voluntary termination of pregnancy (TOP). PATIENTS AND METHODS: We made a retrospective descriptive study at the Centre Hospitalier Universitaire (CHU) of Nice. Two hundred (and) four minor patients were included, from January 1st 2003 to December 31st 2004. RESULTS: In the majority of cases, the entourage (sexual partner or parents) who are informed of the request for TOP support the patient in her choice. In more than 56% of cases, the parents are not informed of the request for TOP. DISCUSSION AND CONCLUSION: It seems, for minors, that it is the need for conforming to the existing social model which motivates the majority of the requests for TOP.

Oncocytic cyst of the larynx: an unusual occurrence.

Oncocytic cysts of the larynx are rare benign, slow growing lesions that are lined predominantly or exclusively by oncocytes, the cytoplasm of which contains a considerable number of hypertrophied mitochondria, which accounts for their eosinophilia and swollen appearance. The oncocytic change is a phenomenon of metaplasia which occurs frequently in epithelial endocrine cells with high metabolic activity and it is also associated with inflammation, degenerative process or cellular ageing. In the larynx, oncocytic metaplasia is very uncommon, but it is occasionally seen in the lining of laryngeal cysts, which are found most commonly in the ventricles or in the false vocal cords, where seromucinous glands are more abundant. Oncocytic cysts typically occur in the elderly and are usually solitary, with involvement of an isolated site, whereas diffuse involvement with multiple cysts is extremely rare. Hoarseness is the most common presenting symptom, while pain, stridor or laryngeal obstruction are unusual complaints. Management of these lesions is conservative and consists of local excision, endoscopic removal being the treatment of choice. Although oncocytic cysts are benign lesions, follow-up is recommended, as recurrence is possible, especially in the case of patients with multiple involvement, since they may show a tendency to develop new cysts. To date, approximately 150 cases of laryngeal oncocytic cysts have been published. Herein, a very unusual case is presented occurring in a 43-year-old male patient, therefore, "epidemiologically" atypical for developing oncocytic lesions. Causes of oncocytic changes and pathogenesis of laryngeal cysts are discussed.

Lifestyle use of drugs by healthy people for enhancing cognition, creativity, motivation and pleasure.

Today, there is continued, and in some cases growing, availability of not only psychoactive substances, including treatments for mental health disorders such as cognitive enhancers, which can enhance or restore brain function, but also 'recreational' drugs such as novel psychoactive substances (NPS). The use of psychoactive drugs has both benefits and risks: whilst new drugs to treat cognitive symptoms in neuropsychiatric or neurodegenerative disorders could have great benefits for many patient groups, the increasing ease of accessibility to recreational NPS and the increasing lifestyle use of cognitive enhancers by healthy people means that the effective management of psychoactive substances will be an issue of increasing importance. Clearly, the potential benefits of cognitive enhancers are large and increasingly relevant, particularly as the population ages, and for this reason, we should continue to devote resources to the development of cognitive enhancers as treatments for neurodegenerative diseases and psychiatric disorders, including Alzheimer's disease, attention deficit hyperactivity disorder and schizophrenia. However, the increasing use of cognitive enhancers by healthy individuals raises safety, ethical and regulatory concerns, which should not be ignored. Similarly, understanding the short- and long-term consequences of the use of NPS, as well as better understanding the motivations and profiles of users could promote more effective prevention and harm reduction measures. Linked Articles This article is part of a themed section on Pharmacology of Cognition: a Panacea for Neuropsychiatric Disease? To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.19/issuetoc.

WITHDRAWN: Neurotrophins and specific receptors in the oviduct tracts of Japanese quail (Coturnix coturnix japonica).

The Publisher regrets that this article is an accidental duplication of an article that has already been published in Ann. Anat., 210 (2017) 112 ­ 120>, http://dx.doi.org/10.1016/j.aanat.2016.04.034. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Expression and distribution of leptin and its receptors in the digestive tract of DIO (diet-induced obese) zebrafish.

The expression and localization of leptin (A and B) and its receptor family in control and diet-induced obese (DIO) adult male zebrafish gut, after 5-weeks overfeeding, administering Artemia nauplii, as fat-rich food, were investigated. Recently, the obese adult zebrafish was considered an experimental model with pathophysiological pathways similar to mammalian obesity. Currently, there are no reports about leptin in fish obesity, or in a state of altered energy balance. By qRT-PCR, leptin A and leptin B expression levels were significantly higher in DIO zebrafish gut than in the control group (CTRL), and the lowest levels of leptin receptor mRNA appeared in DIO zebrafish gut. The presence of leptin and its receptor proteins in the intestinal tract was detected by western blot analysis in both control and DIO zebrafish. By single immunohistochemical staining, leptin and leptin receptor immunoreactive endocrine cells were identified in the intestinal tract either in DIO or control zebrafish. Moreover, leptin immunopositive enteric nervous system elements were observed in both groups. By double immunohistochemical staining, leptin and its receptor were colocalized especially in DIO zebrafish. Thus, our study represents a starting point in the investigation of a possible involvement of leptin in control of energy homeostasis in control and DIO zebrafish.

[Bening enterogenital fistulas arising from the digestive tract: three cases]. / Fistules entérogénitales d'origine digestive bénigne: à propos de trois cas.

Fistulas between the female genital tract and the digestive tract occur after obstetrical, oncological, or post-operative complications. We report herein 3 rare cases of enterogenital fistulas: one colouterine fistula and one colotubal fistula in a patient with diverticulitis, and one ileovaginal fistula in a patient with Crohn's disease. Vaginal discharge was frequent and incited patients to consult a gynecologist. Better knowledge of enterogenital fistulas is necessary to enable earlier diagnosis and apply specific treatment. The incidence of colovaginal fistulas is increasing in diverticular disease because of increased prevalences of hysterectomies and diverticular disease.

Neurotrophin-4 in the brain of adult Nothobranchius furzeri.

Neurotrophin-4 (NT-4) is a member of the well-known family of neurotrophins that regulate the development of neuronal networks by participating in neuronal survival and differentiation, the growth of neuronal processes, synaptic development and plasticity, as well as myelination. NT-4 interacts with two distinct receptors: TrkB, high affinity receptor and p75 low-affinity neurotrophin receptor (p75(NTR)). In the present survey, we identified the gene encoding NT-4 in the teleost Nothobranchius furzeri, a model species for aging research. The identified gene shows a similarity of about 72% with medaka, the closest related species. The neuroanatomical localization of NT-4 mRNA is obtained by using an LNA probe. NT-4 mRNA expression is observed in neurons and glial cells of the forebrain and hindbrain, with very low signal found in the midbrain. This survey confirms that NT-4 is expressed in the brain of N. furzeri during adulthood, suggesting that it could also be implicated in the maintenance and regulation of neuronal functions.

Neurotrophins and specific receptors in the oviduct tracts of Japanese quail (Coturnix coturnix japonica).

Neurotrophins (NGF, BDNF and NT-3) and their specific receptors (TrkA, TrkB and TrkC) were studied in the oviduct of egg laying quails. Neurotrophins (NTs) are mainly involved in the development and maintenance of neuronal populations in the central and peripheral nervous system, but also in reproductive system. In this survey, we first studied the morphological organization of the quail oviduct, distinguished in infundibulum, magnum, isthmus, uterus and vagina, and then we analyzed the expression and localization of NTs and Trks receptors in the whole tracts. By western blotting we detected that the investigated NTs and Trks receptors are expressed in all oviductal tracts. By immunohistochemistry we were able to define the distribution of NTs and Trks. Specifically, NGF, BDNF and NT3 were localized in lining and ductal epithelial cells, and NGF was also detected in secretory cells of tubular glands and in nervous fibers of vessel wall. TrkA and TrkB were present in the lining and ductal epithelium; TrkA and TrkC were present in nervous fibers of vessel wall in all oviductal tracts. Furthermore, we also observed NGF and BDNF co-localized with TrkA and TrkB in cells of the lining and ductal epithelium, suggesting an autocrine mechanism of action.

Propolis and swimming in the prevention of atherogenesis and left ventricular hypertrophy in hypercholesterolemic mice.

AIMS: The present study verified the effect of propolis alone and its association with swimming in dyslipidemia, left ventricular hypertrophy and atherogenesis of hypercholesterolemic mice. METHODS AND RESULTS: The experiments were performed in LDLr-/- mice, fed with high fat diet for 75 days, and were divided into four experimental groups (n=10): HL, sedentary, subjected to aquatic stress (5 min per day, 5 times per week); NAT submitted to a swimming protocol (1 hour per day, 5 times per week) from the 16th day of the experiment; PRO, sedentary, submitted to aquatic stress and which received oral propolis extract (70 uL/animal/day) from the 16th day of the experiment; HL+NAT+PRO, submitted to swimming and which received propolis as described above. After 75 days, blood was collected for analysis of serum lipids. The ratio between the ventricular weight (mg) and the animal weight (g) was calculated. Histological sections of the heart and aorta were processed immunohistochemically with anti-CD40L antibodies to evaluate the inflammatory process; stained with hematoxylin/eosin and picrosirius red to assess morphological and morphometric alterations. The HL animals showed severe dyslipidemia, atherogenesis and left ventricular hypertrophy, associated with a decrease in serum HDLc levels and subsequent development of cardiovascular inflammatory process, characterized by increased expression of CD40L in the left ventricle and aorta. Swimming and propolis alone and\or associated prevented the LVH, atherogenesis and arterial and ventricular inflammation, decreasing the CD40L expression and increasing the HDLc plasmatic levels. CONCLUSION: Propolis alone or associated with a regular physical activity is beneficial in cardiovascular protection through anti-inflammatory action.

Radiation therapy in the management of symptomatic bone metastases: the effect of total dose and histology on pain relief and response duration.

PURPOSE: In order to better define variables and factors that may influence the pain response to radiation, and to look for a radiation regimen that can assure the highest percentage and the longest duration of pain relief, we performed a prospective, although not randomized, study on patients with bone metastases from various primary sites. METHODS AND MATERIALS: From December 1988 to March 1994, 205 patients with a total of 255 solitary or multiple bone metastases from several primary tumors were treated in our radiotherapy center with palliative intent. Irradiation fields were treated with three main fractionation schedules: (1) Conventional fractionation: 40-46 Gy/20-23 fractions in 5-5.5 weeks; (2) Short course: 30-36 Gy/10-12 fractions in 2-2.3 weeks; (3) Fast course: 8-28 Gy/1-4 consecutive fractions. Pain intensity was self-assessed by patients using a visual analogic scale graduated from 0 (no pain) to 10 (the strongest pain one can experience). Analgesic requirement was assessed by using a five-point scale, scoring both analgesic strength and frequency (0 = no drug or occasional nonopioids; 1 = Nonopioids once daily; 2 = Nonopioids more than once daily; 3 = Mild opioids (oral codeine, pentazocine, etc.), once daily; 4 = Mild opioids more than once daily; 5 = Strong opioids (morphine, meperidine, etc.). Complete pain relief meant the achievement of a score < or = 2 in the pain scale or 0 in the analgesic requirement scale. Partial pain relief indicated a score of 3 to 4 or of 1 to 2 on the former and latter scale, respectively. RESULTS: Total pain relief (complete + partial) was observed in 195 (76%) sites, in 158 of which (62%) a complete response was obtained. Metastases from NSC lung tumors appeared to be the least responsive among all primary tumors, with 46% complete pain relief in comparison to 65% and 83% complete relief in breast (p = 0.04) and in prostate metastases (p = 0.002), respectively. A significant difference in pain relief was detected among the several ranges of total dose delivered to the painful metastases, with 81%, 65%, and 46% complete relief rates in the 40-46 Gy, 30-36 Gy (p = 0.03), and 8-28 Gy (p = 0.0001) dose ranges respectively. A straight correlation between total dose and complete pain relief was confirmed by the curve calculated by the logistic model which shows that doses of 30 Gy or more are necessary to achieve complete pain relief in 70% or more of bone metastases. This correlation holds also for the duration of pain control, as shown by the actuarial analysis of time to pain progression. Multivariate analyses, with complete pain relief and time to pain progression as endpoints show a highly significant effect of radiation dose (p = 0.0007) and performance status (p = 0.003), with lower rates of complete pain relief and shorter time to pain progression observed after smaller radiation total doses or higher Eastern Cooperative Oncology Group (ECOG) scores. CONCLUSION: Although single-dose or short course irradiation is an attractive treatment in reducing the number of multiple visits to radiotherapy departments for patients with painful bone metastases, it is nevertheless clear that aggressive protracted treatments seem to offer significant advantages especially for patients in whom the expected life span is not short.

Human immunodeficiency virus infection in urban adolescents: can we predict who is at risk?

Few studies have evaluated the extent of human immunodeficiency virus (HIV) in the adolescent population. However, there has been growing concern that sexual and drug experimentation common in this age group may increase their risks of transmitting the virus. Between October 1, 1987, and January 31, 1989, a blinded, unlinked HIV seroprevalence study was conducted among all adolescents aged 13 through 19 receiving ambulatory care at Children's National Medical Center and having blood drawn for other routine medical indications. Overall, seroprevalence in this group of patients was 0.37% (3.7/1000), with the highest prevalence in females (4.7/1000) and patients 18 through 19 years of age (5.6/1000). Of adolescents considered at high risk who were offered and accepted voluntary HIV testing during the same time period, 4.1% (41/1000) were positive. Inasmuch as this represents only 38% of all of the positive tests obtained in the blinded testing phase of the study, it may indicate that a substantial proportion of HIV-positive adolescent patients may be missed by using standard criteria and methods of identifying risk and/or that those most at risk may be reluctant to be tested for HIV infection. The results suggest that HIV infection is present in this population of urban adolescents and that the seroprevalence rate is higher than in other nonselect groups. Moreover, using traditional risk factors as screening criteria may not identify the majority of those infected. Trends need to be followed and further studies conducted in an attempt to define which adolescents are at highest risk for HIV infection.