Role of pulsatility on particle dispersion in expiratory flows

Expiratory events, such as coughs, are often pulsatile in nature and result in vortical flow structures that transport respiratory particles. In this work, direct numerical simulation (DNS) of turbulent pulsatile jets, coupled with Lagrangian particle tracking of micron-sized droplets, is performed to investigate the role of secondary and tertiary expulsions on particle dispersion and penetration. Fully developed turbulence obtained from DNS of a turbulent pipe flow is provided at the jet orifice. The volumetric flow rate at the orifice is modulated in time according to a damped sine wave, thereby allowing for control of the number of pulses, duration, and peak amplitude. Thermodynamic effects, such as evaporation and buoyancy, are neglected in order to isolate the role of pulsatility on particle dispersion. The resulting vortex structures are analyzed for single-, two-, and three-pulse jets. The evolution of the particle cloud is then compared to existing single-pulse models. Particle dispersion and penetration of the entire cloud are found to be hindered by increased pulsatility. However, the penetration of particles emanating from a secondary or tertiary expulsion is enhanced due to acceleration downstream by vortex structures.

The use of phenome-wide association studies (PheWAS) for exploration of novel genotype-phenotype relationships and pleiotropy discovery

The field of phenomics has been investigating network structure among large arrays of phenotypes, and genome-wide association studies (GWAS) have been used to investigate the relationship between genetic variation and single diseases/outcomes. A novel approach has emerged combining both the exploration of phenotypic structure and genotypic variation, known as the phenome-wide association study (PheWAS). The Population Architecture using Genomics and Epidemiology (PAGE) network is a National Human Genome Research Institute (NHGRI)-supported collaboration of four groups accessing eight extensively characterized epidemiologic studies. The primary focus of PAGE is deep characterization of well-replicated GWAS variants and their relationships to various phenotypes and traits in diverse epidemiologic studies that include European Americans, African Americans, Mexican Americans/Hispanics, Asians/Pacific Islanders, and Native Americans. The rich phenotypic resources of PAGE studies provide a unique opportunity for PheWAS as each genotyped variant can be tested for an association with the wide array of phenotypic measurements available within the studies of PAGE, including prevalent and incident status for multiple common clinical conditions and risk factors, as well as clinical parameters and intermediate biomarkers. The results of PheWAS can be used to discover novel relationships between SNPs, phenotypes, and networks of interrelated phenotypes; identify pleiotropy; provide novel mechanistic insights; and foster hypothesis generation. The PAGE network has developed infrastructure to support and perform PheWAS in a high-throughput manner. As implementing the PheWAS approach has presented several challenges, the infrastructure and methodology, as well as insights gained in this project, are presented herein to benefit the larger scientific community.

Do urinary estrogen metabolites reflect the differences in breast cancer risk between Singapore Chinese and United States African-American and white women?

Breast cancer risk is substantially lower in Singapore than in women from the United STATES: Part of the risk discrepancy is probably explained by differences in the production of endogenous estrogens, but differences in the pathway by which estrogen is metabolized may also play a role. We undertook a study to determine whether the ratio of urinary 2-hydroxyestrone (2OHE(1)):16alpha-hydroxyestrone (16alpha-OHE(1)) was higher in Singapore Chinese than in a group of United States (predominantly African-American) women living in Los ANGELES: We also wanted to determine whether any difference in estrogen metabolite ratio between these two groups of women was greater than that in estrone (E(1)), estradiol (E(2)) and estriol (E(3)). The participants in this study were randomly selected healthy, non-estrogen using women participating in the Singapore Chinese Health Study (n = 67) or the Hawaii/Los Angeles Multiethnic Cohort Study (n = 58). After adjusting for age and age at menopause, mean urinary 2-OHE(1) was only 23% (P = 0.03) higher in Singapore Chinese than in United States women, and there were no statistically significant differences in 16alpha-OHE(1) levels or in the ratio of 2-OHE(1):16alpha-OHE(1) between the two groups. The adjusted mean 2-OHE(1):16alpha-OHE(1) ratio was 1.63 in Singapore Chinese and 1.48 in United States women (P = 0.41). In contrast, the adjusted mean values of E1, E2, and E3 were 162% (P < 0.0001), 152% (P < 0.0001), and 92% (P = 0.0009) higher, respectively, in United States women than in Singapore Chinese women. Our study suggests that urinary E1, E2, and E3 reflect the differences in breast cancer risk between Singapore Chinese and United States women to a stronger degree than the estrogen metabolites 2OHE(1) and 16alpha-OHE(1) or the ratio of 2OHE(1):16alpha-OHE(1.)

Can clinical parameters predict fractures in acute pediatric wrist injuries?

OBJECTIVE

Fractures around the wrist are common in pediatric patients presenting to the emergency department (ED). This pilot study was aimed at identifying clinical variables that are most likely to be associated with a fracture.

METHODS

This was a prospective blinded case series of patients 3-18 years of age presenting with an acute (<3 days) wrist injury, without obvious deformity. A team of five investigators blinded to the eventual radiographic findings evaluated patients. Physical examination variables included range of motion (ROM), site of maximal tenderness, and functional deficit. The latter was determined objectively, by recording any difference in grip strength between the injured and noninjured hands. Diagnostic radiographs were obtained for all patients. Univariate analysis using Wilks' log likelihood ratio test was performed to identify clinical variables associated with confirmed wrist fractures. Sample size was determined based on the ability to detect a difference of 15 degrees in the ROM variables, 20% point differences in grip strength, and 30% proportion differences in categorical variables using a power of 0.8 and a two-tailed of 0.05.

RESULTS

The ROMs were not significantly different between the fracture (Fx) and nonfracture (NFx) group. There was significant change in the grip strength between the Fx and NFx groups (t = 3.3, p = 0.0019). Tenderness over the distal radius was also associated with a greater likelihood of a fracture (G(2) = 5.0, p = 0.02). Sensitivity of clinical prediction was found to be 79%, and specificity was 63%. The false-negative rate was 0.21 and the false-positive rate was 0.37, while the positive predictive value was found to be 0.68 and negative predictive value 0.75.

CONCLUSIONS

Distal radius point tenderness and a 20% or more decrease in grip strength were predictive of fractures.

Childhood hypoglycemia in an urban emergency department: epidemiology and a diagnostic approach to the problem

OBJECTIVE

To 1) determine the prevalence of hypoglycemia in childhood in a pediatric emergency department (ED), 2) determine epidemiology of idiopathic ketotic hypoglycemia (IKH), 3) determine diagnostic yield of the workup of hypoglycemia, and 4) review a diagnostic approach to hypoglycemia.

SETTING

Urban pediatric ED of a tertiary level children's hospital.

METHODS

Retrospective review of all medical records with a primary or secondary diagnosis of hypoglycemia (ICD-9 code 251.2) seen at the ED between 1/92 and 8/95.

RESULTS

Thirty-one patients were identified. Mean blood glucose was 34.2 mg/dl. Prevalence of hypoglycemia among population seeking care in our ED was 6.54/100,000 visits. Eighteen patients were diagnosed with IKH for a prevalence of 3.9/100,000. IKH demographics were: mean age 27.7 months; 12 males, 6 females; 8 white, 9 black, and 1 not available. The weights of five patients were < 25th percentile. Fourteen of the 18 IKH patients had hormone studies done insulin [cost $40], growth hormone [$69], cortisol [$54]. All 14 had appropriately suppressed insulin levels (< 5microU/ml) and high cortisol levels > 22 microg/ml. Thirteen of the 14 had normal or high growth hormone (GH) levels (0.7-6 ng/ml). Four IKH patients had urine drug screens ($280); all were negative. Although no IKH patient was febrile, six had sepsis workups ($380); all were negative. Urine ketones were positive in 15 of the 18 tested (> 3+ in eight patients). Mean anion gap was 20 (range: 16-30). Eight of the 18 IKH patients were discharged from the ED after return to normal status.

CONCLUSIONS

IKH is the most common cause of hypoglycemia in children beyond the infancy period. In its typical presentation (previously healthy one- to five-year-old, with normal growth and development, who presents with a first episode of symptomatic fasting hypoglycemia and appropriate degree of ketonuria, without hepatomegaly, and with resolution of symptoms on administration of glucose), an extensive and overzealous workup for endocrinopathy or inborn error of metabolism is not necessary.

Cancer incidence among Filipinos in Los Angeles County, 1972-1991

Although Filipinos are the second largest Asian subgroup in the United States, little is known about their patterns of cancer incidence. We have examined cancer incidence rates among Filipinos living in Los Angeles County from 1972 through 1991 and evaluated their risk of non-localized cancer relative to non-Hispanic whites. Although Filipinos have substantially lower cancer rates than non-Hispanic whites in Los Angeles County, their incidence rates of liver cancer, cancer of the nasopharynx and thyroid cancer are higher. Filipino men and women had somewhat more advanced cancer at diagnosis, on average, than non-Hispanic whites, though no statistically significant differences were observed for sites where early detection methods exist. Our data suggest that Filipino-Americans would benefit from increased screening for cervical and breast cancer as well as efforts to interrupt transmission of hepatitis B virus to reduce liver cancer incidence.

A case-control study of maternal risk factors for thyroid cancer in young women (California, United States)

A population-based case-control interview study investigated whether reproductive factors are related to the striking female-over-male excess of thyroid cancer among women of reproductive age in Los Angeles County, CA (United States). As a separate component of that study, mothers of 153 cases and 140 controls who were age 40 or younger at diagnosis or reference date were interviewed by telephone to determine the significance of family and maternal risk factors in the subsequent development of thyroid cancer among the daughters. More case than control mothers experienced miscarriage prior to the index pregnancy (odds ratio [OR] = 2.0, 95 percent confidence interval [CI] = 1.1-3.5). Increased risk was associated with family history of thyroid cancer or other thyroid disease (OR = 2.1, CI = 1.2-3.6). More control than case mothers smoked during the index pregnancy (OR = 0.6, CI = 0.4-1.0); however, among mothers who smoked, case mothers smoked more. Case mothers experienced a greater increase in weight from minimum adult weight to weight at index pregnancy (P for trend = 0.01). Reports from mothers also confirmed the risk associated with the daughter's exposure to ionizing radiation from birth through adolescence; ionizing radiation remains the best-established risk factor for thyroid cancer.

Spinal meningiomas in women in Los Angeles County: investigation of an etiological hypothesis

A series of 3 studies explored the hypothesis that the preponderance of spinal meningiomas among postmenopausal women relates to their higher prevalence of spinal osteoporosis: (a) medical records showed that meningiomas in women, unlike other spinal tumors, usually arise in the mid thoracic spine where osteoporotic vertebral fractures predominate; (b) radiographic evidence of osteoporosis was seen commonly with meningiomas but not with other spinal tumors; and (c) age-adjusted multivariate analysis of data from an interview study of 81 women with spinal meningioma and 155 random digit dial controls showed 6 factors related to risk. Four factors were protective: (a) current use (at diagnosis) of estrogen replacement therapy [odds ratio (OR) = 0.2; 95% confidence interval (CI) = 0.1-0.6]; (b) past use of oral contraceptives (P trend < 0.01); (c) past participation in sports (OR = 0.5; CI = 0.2-0.9); and (d) premenopausal status (OR = 0.2; CI = 0.1-0.7). Risk increased among women who had ever smoked cigarettes (OR = 1.7; CI = 0.9-3.1) or had a history of high dose radiography (> 500 mrad exposure to active marrow/examination; includes upper or lower gastrointestinal series and/or cardiac angiography; OR = 2.9, and CI = 1.6-5.3), although no association was seen with prior radiotherapy. Other results that did not support the hypothesis include findings that cases and controls were similar in mean body weight and in the proportion who had postmenopausal fractures or height loss. In conclusion, these studies lend some support to our hypothesis, but other known meningioma risk factors such as ionizing radiation also appear important.(ABSTRACT TRUNCATED AT 250 WORDS)

Physiologic and pathologic evaluation of chronic extra-aortic counterpulsation with latissimus dorsi flap. Preliminary results

This study attempted to evaluate the efficacy of chronic extra-aortic counterpulsation with a latissimus dorsi neuro vascular flap. Five dogs had a preliminary procedure consisting of the creation of a latissimus dorsi flap and a thoracotomy in which the flap was wrapped around the descending aorta just distal to the left subclavian artery. An epicardial lead was placed on the left ventricle and a nerve stimulating lead placed around the thoraco-dorsal nerve. Three weeks later, both leads were connected to a cardiomyostimulator programmed to function in a counterpulsation mode with a 1:2 assist frequency. Hemodynamic measurements were made at 6 and 8 and 10 and 12 weeks and the dogs were sacrificed. Three dogs had all sets of hemodynamic measurements made. Two of the three dogs demonstrated diastolic augmentation at 6 and 8 and 10 and 12 weeks average 20 to 25 mmHg. The third dog failed to demonstrate any change. All dogs were sacrificed at 12 weeks and specimens were submitted for histologic evaluation. The muscle flap was preserved in all animals. The aorta subjacent to the flap showed, (1) normal intima with no evidence of disruption or thrombus in all animals, (2) in the animals in whom counterpulsation was observed, there appeared to be thinning of the media in the aorta subjacent to the muscle flap, and (3) no evidence of distal emboli. This study demonstrated that chronic counterpulsation can be obtained with a latissimus dorsi flap. The actual hemodynamic benefits are not determined from this study. The medial thinning in the aortic wall may limit the long-term benefit of this procedure.

Management of indirect inguinal hernias by laparoscopic closure of the neck of the sac

Fifteen animals with indirect inguinal hernias were treated by closure of the abdominal opening of the patent processus vaginalis by the application of staples laparoscopically. The satisfactory results confirm those obtained in a previous study, where similar openings found during laparotomy for abdominal surgery were closed by the application of metal clips. Laparoscopic closure of the abdominal opening of a hernial sac may have advantages over the present operative management.