A Mixed-Methods Approach to Develop a Combined Model of U.S. College Student Alcohol-Associated Condomless Sex

Unhealthy alcohol use and sexually transmitted infections (STIs) are significant public health concerns for US college students. Because alcohol use and condomless sex often co-occur in this population, alcohol-associated condomless sex has been identified as a behavioral intervention target. Existing theoretical frameworks have not garnered sufficient empirical support to serve as the foundation for interventions. The primary goal of the current study was to use a mixed-methods approach to develop a model of college student alcohol-associated condomless sex that combines elements from well-established health behavior theories. In Aim 1, multilevel modeling was used to predict condomless vaginal sex in a sample of heterosexual college student drinkers (N = 53). Aim 2 consisted of in-depth interviews (n = 18) to gather perceptions about the role of alcohol in sexual activity and identify supplemental constructs omitted from theories in Aim 1. The multilevel model explained a significant proportion of variance in condomless vaginal sex at the between- and within-person level. Themes derived from the in-depth interviews identified complementary elements of condom use decision-making. Findings from both aims were synthesized to construct a combined model of alcohol-associated condomless sex. This model can be further refined and ultimately serve as the foundation of an alcohol-STI prevention-intervention.

Is the whole the sum of its parts? Agent-based modelling of wastewater treatment systems

Agent-based models (ABMS) simulate individual units within a system, such as the bacteria in a biological wastewater treatment system. This paper outlines past, current and potential future applications of ABMs to wastewater treatment. ABMs track heterogeneities within microbial populations, and this has been demonstrated to yield different predictions of bulk behaviors than the conventional, "lumped" approaches for enhanced biological phosphorus removal (EBPR) completely mixed reactors systems. Current work included the application of the ABM approach to bacterial adaptation/evolution, using the model system of individual EBPR bacteria that are allowed to evolve a kinetic parameter (maximum glycogen storage) in a competitive environment. The ABM approach was successfully implemented to a simple anaerobic-aerobic system and it was found the differing initial states converged to the same optimal solution under uncertain hydraulic residence times associated with completely mixed hydraulics. In another study, an ABM was developed and applied to simulate the heterogeneity in intracellular polymer storage compounds, including polyphosphate (PP), in functional microbial populations in enhanced biological phosphorus removal (EBPR) process. The simulation results were compared to the experimental measurements of single-cell abundance of PP in polyphosphate accumulating organisms (PAOs), performed using Raman microscopy. The model-predicted heterogeneity was generally consistent with observations, and it was used to investigate the relative contribution of external (different life histories) and internal (biological) mechanisms leading to heterogeneity. In the future, ABMs could be combined with computational fluid dynamics (CFD) models to understand incomplete mixing, more intracellular states and mechanisms can be incorporated, and additional experimental verification is needed.

Treatment of acute appendicitis with one-port transumbilical laparoscopic-assisted appendectomy: a six-year, single-centre experience

BACKGROUND

Laparoscopic appendectomy is a feasible and safe alternative to open appendectomy for uncomplicated appendicitis. In the past decade several laparoscopic procedures have been described using one or more ports. We report our experience in treating acute appendicitis with one-port transumbilical laparoscopic-assisted appendectomy (TULAA).

PATIENTS AND METHODS

We performed 231 TULAA on patients in the period from November 2001 to September 2007. We introduced an 11 mm Hasson's port using open technique; an operative channel with 10 mm telescope and an atraumatic grasper were used. After intra-abdominal laparoscopic dissection, the appendix was exteriorised through the umbilical access. The appendectomy was performed outside the abdomen as in the open procedure; the operation was completed using only one port in 227 patients (98%), two and three ports in two patients (1%) while conversion to open surgery was needed in two patients (1%).

RESULTS

The average operating time was 38 minutes and the median time to discharge was three days. Four (1, 7%) early postoperative complications (two suppuration of the umbilical wound) with no major complications were observed.

CONCLUSIONS

Our results demonstrate that TULAA, which combines the advantages of both open and laparoscopic procedures, is a valid alternative form of treating uncomplicated appendicitis. If appendectomy cannot be completed with only one port, insertion of one or more ports may be necessary to safely conclude the procedure.

Short-term effects of atenolol and nifedipine on atrial natriuretic peptide, plasma renin activity, and plasma aldosterone in patients with essential hypertension

The short-term effects of atenolol and nifedipine on plasma levels of atrial natriuretic peptide (ANP), plasma renin activity (PRA), and plasma aldosterone (PA) were studied in two groups of patients with uncomplicated essential hypertension. Urinary catecholamines, and sodium and potassium excretion were also studied. A group of 20 patients with hypertension, after a wash-out period of at least 10 days, was randomly subdivided into two protocol therapy subgroups. One group (six men and four women) received atenolol (100 mg/d), and the other group (six men and four women) received nifedipine (30 mg/d). Circulating plasma levels of ANP, PRA, and PA were determined by radioimmunoassay, and other variables were determined by routine laboratory techniques before therapy and at day 3 and day 7 after the treatment began. Arterial blood pressure and heart rate were monitored during the study. Both drugs reduced arterial blood pressure (P less than .001) significantly. The atenolol therapy decreased heart rate (P less than .001), increased plasma ANP levels and urinary catecholamine excretion, and decreased PRA and circulating PA levels. Nifedipine treatment did not modify plasma ANP values, whereas it increased PRA and PA circulating levels and urinary catecholamine excretion. No differences were shown for urinary volume, urinary sodium, and potassium excretions during the two different treatments. These findings suggest that the increased plasma ANP levels could contribute to the antihypertensive effects of the beta-adrenoreceptor blockers, by a reduction in PRA and PA levels and a vasodilatative effect.(ABSTRACT TRUNCATED AT 250 WORDS)

[Differentiated circadian chrono-risk of acute myocardial infarct]

In order to determine whether acute myocardial infarction (AMI) presents a circadian periodicity in its occurrence, the onset of AMI, evaluated by onset of clinical symptoms and pain, has been analysed in 520 patients with AMI. The definitive criteria of AMI were: typical chest pain, electrocardiographic findings, and plasma CPK-MB elevation. All cases of AMI were divided into subgroups according to sex (males = 369, females = 151), age (less than 60 years old = 254, more than 60 years old = 266), type of AMI (Q wave AMI = 407, non Q wave AMI = 113), previous pharmacological treatment (no treated = 373, treated = 147), history of arterial blood hypertension (normotensive = 403, hypertensive = 117). Cases of Q and non Q wave AMI were also subdivided according to treatment and hypertensive conditions. All AMI occurred outside hospital; silent AMI and reinfarctions were excluded by analyses. The data have been analysed by chronograms and by means of "single cosinor" method, both for total cases, and for each subgroup of AMI. The results show a diurnal variation in AMI occurrence regarding the whole group, with a peak from 4:00 am to noon and with a secondary small no-significant peak in the late evening, and the minimum in the afternoon. Rhythmometric analysis demonstrates a significant circadian rhythm (p less than 0.001) with acrophase at 7:52 am (from 6:08 am to 9:36 am). A statistically-significant circadian rhythm is demonstrated in each subgroup, except in hypertensive patients. Acrophases of males and females, and of patients aged over or under 60 years do not differ from that of the whole group, and between them (p greater than 0.05). The peak of non Q wave AMI occurs at 4:44 am, while the peak of Q wave AMI at 10:08 am: this difference is significant (p less than 0.001). There is also a significant difference between the acrophases of AMI in the treated and untreated groups (p less than 0.01), as well as between normotensive and hypertensive subjects (p less than 0.001). The previous treatment seems able to anticipate the maximum occurrence of AMI in the whole group and in the group of Q wave AMI. These results are very similar to previous observations and confirm the greater morning occurrence of AMI. The present data are discussed in respect with the literature observations, and the possible pathophysiological mechanisms that contribute and conditionate the morning increase and the different peaks in subgroups of AMI patients are discussed.(ABSTRACT TRUNCATED AT 400 WORDS)