Extracellular and cellular Hsp72 differ as biomarkers in acute exercise/environmental stress and recovery.

Stress-inducible Hsp72 is a potential biomarker to track risk of exertional heat illness during exercise/environmental stress. Characterization of extracellular (eHsp72) vs cellular Hsp72 (iHsp72) responses is required to define the appropriate use of Hsp72 as a reliable biomarker. In each of four repeat visits, participants (n = 6 men, 4 trials; total n = 24): (a) passively dehydrated overnight, (b) exercised (2 h) with no fluid in a hot, humid environmental chamber, (c) rested and rehydrated (1 h), (d) maximally exercised for 0.5 h, and (e) returned after 24 h of at-home recovery and rehydration. We measured rectal temperature, hydration status (% body mass loss, urine markers, serum osmolality), and Hsp72 (ELISA, flow cytometry. eHsp72 (circulating) and iHsp72 (CD3+ PBMCs) correlated (P < 0.05) with markers of heat, exercise, and dehydration stresses. eHsp72 immediately post-exercise (>15% above baseline, P < 0.05) decreased back to baseline levels by 1 h post-exercise, but iHsp72 expression continued to rise and remained elevated 24 h post-exercise (~2.5-fold baseline, P < 0.05). These data suggest that in addition to the classic physiological biomarkers of exercise heat stress, using cellular Hsp72 as an indicator of lasting effects of stress into recovery may be most appropriate for determining long-term effects of stress on risk for exertional heat illness.

Mecp2 truncation in male mice promotes affiliative social behavior.

Mouse models of Rett syndrome, with targeted mutations in the Mecp2 gene, show a high degree of phenotypic consistency with the clinical syndrome. In addition to severe and age-specific regression in motor and cognitive abilities, a variety of studies have demonstrated that Mecp2 mutant mice display impaired social behavior. Conversely, other studies indicate complex enhancements of social behavior in Mecp2 mutant mice. Since social behavior is a complicated accumulation of constructs, we performed a series of classic and refined social behavior tasks and revealed a relatively consistent pattern of enhanced pro-social behavior in hypomorphic Mecp2 (308/Y) mutant mice. Analyses of repetitive motor acts, and cognitive stereotypy did not reveal any profound differences due to genotype. Taken together, these results suggest that the mutations associated with Rett syndrome are not necessarily associated with autism-relevant social impairment in mice. However, this gene may be a valuable candidate for revealing basic mechanisms of affiliative behavior.

Dual candidemia detected by nested polymerase chain reaction in two critically ill children.

The use of improved microbiological procedures associated with molecular techniques has increased the identification of Candida bloodstream infections, even if the isolation of more than one species by culture methods remains uncommon. We report the cases of two children presenting with severe gastrointestinal disorders and other risk factors that contribute to Candida infections. In the first patient, C. albicans DNA was initially detected by a nested-amplification and C. tropicalis was found later during hospitalization, while blood cultures were persistently negative. In the second child, there was amplification of C. albicans and C. glabrata DNA in the same samples, but blood cultures yielded only C. albicans. Both patients received antifungal therapy but had unfavorable outcomes. These two cases illustrate that PCR was more successful than culture methods in detecting Candida in the bloodstream of high risk children, and was also able to detect the presence of more than one species in the same patient that might impact therapy when the fungi are resistant to azole compounds.

Importância do controle de qualidade para a redução das amostras insatisfatórias cérvico-vaginais / The importance of quality control to reduce unsatisfactory cervicl smears

O objetivo deste estudo foi analisar as não-conformidades analíticas dos exames citopatológicos realizados no Setor de Citologia Oncótica, da Divisão de Patologia do Instituto Adolfo Lutz (SCO-IAL), e discutir ações corretivas para minimizar essas ocorrências. O SCO-IAL recebeu 44.197 amostras citopatológicas cérvico-vaginais enviadas pelas Unidades de Saúde (US), de setembro de 2005 a fevereiro de 2007, que foram coradas pelo método de Papanicolaou e classificadas segundo a Nomenclatura Brasileira recomendada pelo Ministério da Saúde. Do total, 1.155 (2,61%) foram classificadas como insatisfatórias, sendo: 351 por artefatos de dessecamento; 198 pela presença de piócitos; 98 por material insuficiente; 47 pela presença de sangue e 12 por superposição celular. Em 449 casos, houve associação de duas ou mais causas; sendo o dessecamento presente em 351 casos. Das 198 amostras insatisfatórias pela presença de piócitos, 37 apresentaram agentes infecciosos. Observou-se também nesse mesmo período que dos 1.558(3.52%) casos de atipias de significado indeterminado, 371 foram limitados em seu diagnóstico. Os resultados obtidos demonstram que programas de treinamento nas US são de melhor estratégia para melhoria na qualidade das amostras. O controle de qualidade interno e externo, desde a colheita até a emissão dos laudos, é fundamental para o sucesso dos programas de rastreamento citológico.

Effect of hydration state on testosterone and cortisol responses to training-intensity exercise in collegiate runners.

Exercise intensity powerfully influences testosterone, cortisol, and testosterone : cortisol ratio (T:C) responses to endurance exercise. Hydration state may also modulate these hormones, and therefore may alter the anabolic/catabolic balance in response to endurance exercise and training. This study examined the effect of running intensity on testosterone, cortisol, and T : C when exercise was initiated in a hypohydrated state. Nine male collegiate runners (age = 20 +/- 0 y, height = 178 +/- 2 cm, mass = 67.0 +/- 1.8 kg, body fat % = 9.8 +/- 0.7 %, V.O2max = 65.7 +/- 1.1 ml.kg (-1).min (-1)) completed four 10-min treadmill runs differing in pre-exercise hydration status (euhydrated, or hypohydrated by 5 % of body mass) and exercise intensity (70 % or 85 % V.O2max). Body mass, urine osmolality, and urine-specific gravity documented fluid balance; blood samples drawn pre-, immediately post-, and 20 min post-exercise were analyzed for testosterone, cortisol, and T : C. Except for heart rate measured during the 70 % V.O2max trials, heart rate, V.O2, and plasma lactate were similar between euhydrated and hypohydrated conditions for a given intensity, suggesting hypohydration did not measurably increase the physiological stress of the exercise bouts. Furthermore, hydration state had no measurable effect on testosterone concentrations before, during, or after exercise at either intensity. Regardless of exercise intensity, cortisol concentrations were greater during hypohydration than euhydration pre-exercise and 20 min post-exercise. Additionally, T : C was significantly lower 20 min post-exercise at 70 % V.O2max when subjects were initially hypohydrated (T : C = 0.055) versus euhydrated (T : C = 0.072). These findings suggest that depending on exercise intensity, T : C may be altered by hydration state, therefore influencing the balance between anabolism and catabolism in response to running exercise performed at typical training intensities.

Tamoxifen down-regulates CaMKII messenger RNA levels in normal human breast tissue.

Tamoxifen was proven to reduce the incidence of breast cancer by 49% in women at increased risk of the disease in the Breast Cancer Prevention Trial. In order to identify potential candidates to explain the preventive effect induced by tamoxifen on breast cancer, normal breast tissue obtained from 42 fibroadenoma patients, randomly assigned to receive placebo or tamoxifen, was analyzed by the reverse Northern blot and RT-PCR techniques. The cDNA fragments used on Northern blot membranes were generated by the Human Cancer Genome Project funded by the Ludwig Institute for Cancer Research and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo, Brazil). Total RNA was obtained from normal breast tissue from patients with clinical, cytological and ultrasound diagnosis of fibroadenoma. After a 50-day treatment with tamoxifen (10 or 20 mg/day) or placebo, normal breast tissue adjacent to the tumor was collected during lumpectomy with local anesthesia. One differentially expressed gene, Calcium/calmodulin-dependent protein kinase II (CaMKII), was found to be down-regulated during TAM treatment. CaMKII is an ubiquitous serine/threonine protein kinase that has been implicated in the diverse effects of hormones utilizing Ca2+ as a second messenger as well as in c-fos activation. These results indicate that the down-regulation of CaMKII induced by TAM might represent alternative or additional mechanisms of the action of this drug on cell cycle control and response to hormones in normal human breast tissue.

Origin of parathyroid hormone (PTH) fragments detected by intact-PTH assays.

BACKGROUND: Intact parathyroid hormone (I-PTH) assays react with non-(1-84)PTH, large carboxyl-terminal (C) fragments with a partially preserved amino-terminal (N) structure. They account for up to 50% of I-PTH in renal failure and may be implicated in PTH resistance. We wanted to know if they were secreted by the parathyroid glands and generated by peripheral metabolism of PTH(1-84). METHODS: Anesthetized normal and nephrectomized (NPX) rats were injected i.v. with 1.5 microg human (h) PTH(1-84). Blood was obtained from 8 rats at 2, 4, 6, 8, 12, 24, 48 and 96 min. I-PTH (Allegro I-PTH) was measured in all samples. Pools of serum were fractionated by HPLC at each time point and the fractions assayed to quantitate hPTH(1-84) and non-(1-84)PTH. Secretion studies were performed with dispersed cells from 5 parathyroid adenomas. The serum of 10 patients with primary hyperparathyroidism and cell supernatants were fractionated by HPLC and were analyzed as described. RESULTS: hPTH(1-84) disappeared from serum biexponentially. The half-life of the first exponential was similar in normal (2.08 min) and NPX (1.94 min) rats, while that of the second was longer in NPX rats (32.4 vs 20.9 min). The residual quantity of hPTH(1-84) under the curve was greater in NPX (6964+/-2392 pmol) than in normal rats (3229+/-561 pmol; P<0.001). Non-(1-84)PTH concentration was maximal at 8 min in both groups and was higher in NPX (92.8+/-13.8 pmol/l) than in normal rats (38.8+/-7.2 pmol/l; P<0.01). The area under the curve of non-(1-84)PTH was also greater in NPX (1904+/-405 pmol) than in normal rats (664+/-168 pmol; P<0.001). All parathyroid adenomas secreted non-(1-84)PTH. It represented 21.1+/-3.9% of secreted and 32.5+/-1.3% of circulating I-PTH in primary hyperparathyroidism. CONCLUSIONS: Non-(1-84)PTH, like other C-PTH fragments, originates from both the peripheral metabolism of hPTH(1-84) and from parathyroid gland secretion. Renal failure influences its concentration by increasing the amount of substrate available and by reducing non-(1-84)PTH clearance. Its higher proportion in serum relative to cell supernatants in primary hyperparathyroidism reflects the added role of peripheral metabolism and the longer half-life of fragments.

Twinfilin is required for actin-dependent developmental processes in Drosophila.

The actin cytoskeleton is essential for cellular remodeling and many developmental and morphological processes. Twinfilin is a ubiquitous actin monomer-binding protein whose biological function has remained unclear. We discovered and cloned the Drosophila twinfilin homologue, and show that this protein is ubiquitously expressed in different tissues and developmental stages. A mutation in the twf gene leads to a number of developmental defects, including aberrant bristle morphology. This results from uncontrolled polymerization of actin filaments and misorientation of actin bundles in developing bristles. In wild-type bristles, twinfilin localizes diffusively to cytoplasm and to the ends of actin bundles, and may therefore be involved in localization of actin monomers in cells. We also show that twinfilin and the ADF/cofilin encoding gene twinstar interact genetically in bristle morphogenesis. These results demonstrate that the accurate regulation of size and dynamics of the actin monomer pool by twinfilin is essential for a number of actin-dependent developmental processes in multicellular eukaryotes.

Telemedicine in a box: overcoming complexity and high-cost telemedicine barriers using self-contained videoconferencing units.

This report describes our experience using low-and moderate-cost videoconferencing systems for telemedicine. After determining that low-cost systems using a standard personal computer and personal computer camera were unsatisfactory, a demonstration project was carried out using a $4000 self-contained videoconferencing unit (telemedicine in a box), using eight simulated telemedicine consultation scenarios. The quality of the videoconferencing was good for all eight scenarios. All eight consultation simulations demonstrated different ways of improving patient care. Two of the major problems hindering the broad proliferation of telemedicine (high cost and high complexity) are solved by the telemedicine in a box concept. Focussing on the telemedicine in a box concept when planning a telemedicine system will improve its feasibility in the real world of health care.

Efficacy of N-acetylcysteine to reduce the effects of aflatoxin B1 intoxication in broiler chickens.

N-acetylcysteine (NAC) has been used safely in humans and in other mammals as an antidote against several toxic and carcinogenic agents, including aflatoxin B1 (AFB1). The aim of this study was to evaluate the capability of dietary supplementation with NAC to ameliorate the effects of subacute intoxication with AFB1 in broiler chickens. One hundred twenty male Hubbard 1-d-old chickens were allocated into one of four dietary treatments: 1) control group without treatment, 2) purified AFB1 added to diet (3 mg/kg of feed) for 21 d, 3) NAC (800 mg/kg BW, daily), or 4) AFB1 plus NAC at the same doses as Groups 2 and 3. Broilers treated with AFB1 plus NAC were shown to be partially protected against deleterious effects on BW (57.8%), daily weight gain (49.1%), feed conversion index (21.4%), plasma and hepatic total protein concentration (45.2, 66.7%), plasma alanine aminotransferase (67.4%), hepatic glutathione-S-transferase (18.8%), and reduced glutathione liver concentration (75.0%). In addition, they showed less intense liver fading, friable texture, and microvesicular steatosis. In the kidney, thickening of glomerular basement membrane was also less severe in NAC+AFB1-treated chickens than in AFB1-treated chickens. Our results suggest that NAC provided protection against negative effects on performance, liver and renal damage, and biochemical alterations induced by AFB1 in broiler chickens. Effects of NAC alone on chick performance were also evaluated. Addition of NAC to diet (800 mg/kg BW) did not negatively affect feed consumption, conversion index, or serum chemistry and did not induce structural changes in the liver or kidney.

Principles of patient safety in pediatrics.

The American Academy of Pediatrics and its members are committed to improving the health care system to provide the best and safest health care for infants, children, adolescents, and young adults. In response to a 1999 Institute of Medicine report on building a safer health system, a set of principles was established to guide the profession in designing a health care system that maximizes quality of care and minimizes medical errors through identification and resolution. This set of principles provides direction on setting up processes to identify and learn from errors, developing performance standards and expectations for safety, and promoting leadership and knowledge.

Injury reduction and bounce characteristics of safety baseballs and acceptability by youth leagues.

The only reasonable way to reduce the potential for ball-related youth baseball injuries sustained by the defensive players (the majority of ball-related injuries) is to make the ball less injurious. The American Academy of Pediatrics' 1994 statement on youth baseball injuries in this regard reads, "Consideration should be given to utilizing low-impact NOCSAE-approved baseballs and softballs for children 5 to 14 years of age, if these balls demonstrate satisfactory playing characteristics and reduce injury risk. A variety of studies should be undertaken to determine the efficacy of low-impact balls in reducing serious impact injuries." The purpose of this study, in accordance with this AAP policy, is to investigate the following: A) injury reduction potential of softer baseballs, B) their bounce characteristics, and C) their acceptability by youth leagues. Six simple injury models were studied, baseball bounce characteristics were analyzed, and attitudes of safety baseballs among statewide Little League district presidents were surveyed. Injury models demonstrated less injury potential with safety baseballs compared to that with standard hard baseballs. Safety baseballs bounced higher after vertical drops and slow throws, but during fast throws (with the greatest injury potential), the bounce heights were similar for all ball types. Of 27 survey cards sent out, 13 were returned. While 9 respondents indicated that they were already using safety baseballs for the younger players, none of the 13 respondents indicated that they were planning to expand the use of safety baseballs in their leagues. In conclusion, safety baseballs are less injurious in these models. The bounce characteristics of safety baseballs are satisfactory. Youth baseball league officials are not very willing to expand the use of safety baseballs. We recommend using safety baseballs as a standard for all youth baseball leagues because these balls are safer.

GPS computer navigators to shorten EMS response and transport times.

GPS (global positioning satellite system to determine one's position on earth) units have become inexpensive and compact. The purpose of this study is to assess the effectiveness of a GPS enhanced computer street map navigator to improve the ability of EMS drivers in an urban setting to locate their destination and shorten response times. For part I, residential addresses in the city were randomly selected from a telephone directory. Two driver/navigator teams were assigned to drive to the address adhering to speed limits. One team used a standard street map, whereas the other team used a GPS computer navigator. The travel time and distance of the runs were compared. For part II, the computer GPS navigator was placed on an ambulance to supplement their normal methods of navigation to find the address requesting EMS. After the run was completed, EMS providers were interviewed to determine their opinion of whether the GPS navigator was helpful. For part I the results showed that in the 29 initial test runs, comparing the GPS team versus the standard map team, the mean distances traveled were 8.7 versus 9.0 kilometers (not significant) and the mean travel times were 13.5 versus 14.6 minutes (P=.02), respectively. The GPS team arrived faster in 72% runs. For part II the results showed that most EMS providers surveyed noted that the GPS computer navigator enhanced their ability to find the destination and all EMS providers acknowledged that it would enhance their ability to find a destination in an area in which they were unfamiliar. These results suggest that a portable GPS computer navigator system is helpful and can enhance the ability of prehospital care providers to locate their destination. Because these units are accurate and inexpensive, GPS computer navigators may be a valuable tool in reducing pre-hospital transport times.

Synthetic carboxyl-terminal fragments of parathyroid hormone (PTH) decrease ionized calcium concentration in rats by acting on a receptor different from the PTH/PTH-related peptide receptor.

Even if the carboxyl-terminal (C-) fragments/intact (I-) PTH ratio is tightly regulated by the ionized calcium (Ca(2+)) concentration in humans and animals, in health and in disease, the physiological roles of C-PTH fragments and of the C-PTH receptor remain elusive. To explore these issues, we studied the influence of synthetic C-PTH peptides of various lengths on Ca(2+) concentration and on the calcemic response to human (h) PTH-(1-34) and hPTH-(1-84) in anesthetized thyroparathyroidectomized (TPTX) rats. We also looked at the capacity of these PTH preparations to react with the PTH/PTHrP receptor and with a receptor for the carboxyl (C)-terminal portion of PTH (C-PTH receptor) in rat osteosarcoma cells, ROS 17/2.8. The Ca(2+) concentration was reduced by 0.19 +/- 0.03 mmol/liter over 2 h in all TPTX groups. Infusion of solvent over 2 more h had no further effect on the Ca(2+) concentration (-0.01 +/- 0.01 mmol/liter), whereas infusion of hPTH-(7-84) or a fragment mixture [10% hPTH-(7-84) and 45% each of hPTH-(39-84) and hPTH-(53-84)] 10 nmol/h further decreased the Ca(2+) concentration by 0.18 +/- 0.02 (P<0.001) and 0.07+/-0.04 mmol/liter (P< 0.001), respectively. Infusion of hPTH-(1-84) or hPTH-(1-34) (1 nmol/h) increased the Ca(2+) concentration by 0.16 +/- 0.03 (P < 0.001) and 0.19 +/- 0.03 mmol/liter (P < 0.001), respectively. Adding hPTH-(7-84) (10 nmol/h) to these preparations prevented the calcemic response and maintained Ca(2+) concentrations equal to or below levels observed in TPTX animals infused with solvent alone. Adding the fragment mixture (10 nmol/h) to hPTH-(1-84) did not prevent a normal calcemic response, but partially blocked the response to hPTH-(1-34), and more than 3 nmol/h hPTH-(7-84) prevented it. Both hPTH-(1-84) and hPTH-(1-34) stimulated cAMP production in ROS 17/2.8 clonal cells, whereas hPTH-(7-84) was ineffective in this respect. Both hPTH-(1-84) and hPTH-(1-34) displaced (125)I-[Nle(8,18),Tyr(34)]hPTH-(1-34) amide from the PTH/PTHrP receptor, whereas hPTH-(7-84) had no such influence. Both hPTH-(1-84) and hPTH-(7-84) displaced (125)I-[Tyr(34)]hPTH-(19-84) from the C-PTH receptor, the former preparation being more potent on a molar basis, whereas hPTH-(1-34) had no effect. These results suggest that C-PTH fragments, particularly hPTH-(7-84), can influence the Ca(2+) concentration negatively in vivo and limit in such a way the calcemic responses to hPTH-(1-84) and hPTH-(1-34) by interacting with a receptor different from the PTH/PTHrP receptor, possibly a C-PTH receptor.

Child literacy promotion in the emergency department.

INTRODUCTION: Studies using primary health care settings to promote literacy have demonstrated success. Since socioeconomically disadvantaged children have less access to primary care, obtaining much of their medical care episodically in emergency departments (ED), the purpose of this study is to investigate the effectiveness of a simple literacy promotion program conducted in the ED and to determine its efficacy and if there is a difference in promoting literacy with a brochure alone versus a brochure plus a children's book. METHODS: Medical student study investigators enrolled patients aged 20 months to 7 years undergoing acute care treatment and evaluation in an ED. Subjects were randomized to a literacy promotion brochure versus a brochure plus a children's book. Phone follow-up interviews were conducted to survey the degree of parental reading taking place at home. RESULTS: Fifty-one families were enrolled, 8 could not be contacted for follow-up, which left 43 families. Twenty-eight were randomized to book + handout and 15 were randomized to handout alone. On follow-up phone interviews, no significant change in reading was demonstrated regardless of whether a brochure alone was given or a book was given with the brochure. CONCLUSION: Literacy promotion in the ED was not associated with any measurable improvement in parent-child reading. This could mean that the ED is not an effective place to promote literacy or confounding factors in this study are responsible for failing to demonstrate a measurable benefit.

Parental pediatric corticosteroid preferences.

Corticosteroids are often prescribed in the acute care management of asthma. Prednisolone can be administered intramuscularly (IM) or orally in 2 different concentrations. This study evaluated parental preference for three prednisolone preparations based on the route of administration, taste, and volume required. Accompanying adults (AAs) of pediatric patients were interviewed about their preferences based on the 3 factors. Those AAs who passed the health screen (51 of 214) were asked to taste 2 oral prednisolone preparations and reinterviewed about their corticosteroid preferences. Of the 214 AAs, 96% were parents. Of the group, 43% preferred IM corticosteroids whereas 40% preferred oral corticosteroids. Without considering taste as a factor for oral corticosteroids, 94% preferred the more concentrated syrup compared with the less concentrated one. When told that the less concentrated syrup tasted better, 58% preferred the less concentrated/better tasting syrup. After the 51 taste test subcohort subjects tasted the syrups, 96% preferred the less concentrated/ better tasting syrup over the more concentrated/poorer tasting syrup. Taste is more important than volume of administration for this particular corticosteroid comparison. Simply asking parents about their IM/oral and syrup formulation preferences may be the easiest way of optimizing their treatment plan.

Revising the decision analysis for febrile children at risk for occult bacteremia in a future era of widespread pneumococcal immunization.

Previous decision analyses (DA), which have attempted to determine a superior management option for febrile children at risk for occult bacteremia, have come to different conclusions based on their underlying assumptions. Most DAs have recommended a laboratory evaluation with antibiotic treatment or have concluded that all management options are roughly the same. The purpose of this revised DA is to determine which management strategy will be superior in an anticipated era of widespread pneumococcal immunization. Decision analysis methodology comparing the following 3 management options: Obs: observation, no tests, no antibiotics; CBC+: Complete blood count (CBC) first; if the white blood cell count (WBC) >15,000, then blood culture (BC) plus antibiotics (Abx); BC+Abx: BC+Abx for all patients. Assumptions include a current bacteremia rate of 2% to 4%, and 95% of this bacteremia is caused by S. pneumococcus (which has a 15% persistent bacteremia rate) with the remainder caused by virulent bacteria (which has a 100% persistent bacteremia rate), and other assumptions made by previous decision analysis publications. Pneumococcal vaccine efficacy rates of 0%, 50%, 75%, and 100% in preventing pneumococcal bacteremia were analyzed. Overall death and neurologic sequelae rates are lower with efficacious pneumococcal vaccine. The Obs strategy is superior for all efficacy rates (including 0%) if the negative consequences of treatment are high. If the negative consequences of treatment are low, the CBC+ strategy is superior at pneumococcal vaccine efficacy rates of 50% or greater. The absolute differences between the outcomes of the 3 strategies are small, making them similar. This decision analysis indicates that widespread efficacious pneumococcal vaccine will reduce the overall morbidity and mortality associated with pneumococcal bacteremia. This favors the Obs strategy, but the superior management strategy is still dependent on an assumption of the negative consequences of treatment. Since the outcome measures for each of the management strategies are similar numerically, the strategy chosen in clinical practice may consider other factors associated with the clinical encounter such as those described.

Distinct chromosomal deleted regions defining different subsets of head and neck tumors.

The aim of this work is detecting the loss of heterozygosity (LOH) and its relationship with the development and progression of head and neck cancer. Matched normal and tumor DNA from 81 patients with head and neck cancer were examined for LOH using six microsatellite repeat markers mapped to chromosomal regions 3p13, 6q13, 9p21, 11p15, 17p13.1, and 17q22. LOH frequency at a locus ranged from 21% to 55%. The highest frequencies were at 3p (41%), 9p (48%), and 17p (54%). Thirty-two of 81 tumor samples showed allelic loss at more than one region. Significant associations were found between LOH at 3p and 9p (P = 0.001), 9p and 11p (P = 0.03), and 9p and 17p (P = 0.007). LOH at 11p was frequent in tumors from the oral cavity (5/17), oropharynx (2/7), and hypopharynx (5/10), but absent in tumors from the larynx (0/11) (P = 0.02), and LOH at 17q was observed in tumors from oral cavity (10/30) and hypopharynx (3/9), but not in tumors from the oropharynx (0/10) or larynx (0/13) (P = 0.003). In addition to that, the occurrence of allelic losses at 9p and 17p strongly correlates to tobacco smoking (P = 0.03 and P = 0.006, respectively) and alcohol intake (P = 0.01 and P = 0.005, respectively). These results suggest that tumors from different sites have different LOH patterns and corroborate with epidemiological data implicating tobacco and alcohol in the etiology of head and neck tumors.