Does contact lead to similarity or similarity to contact?

Evidence from the Finnish Twin Registry (e.g., Rose et al., 1988) shows that adult monozygotic (MZ) twins are more similar, within pairs, in personality if the cotwins are presently cohabiting or in frequent contact than if they are seldom in contact. Results of a follow-up study led Kaprio et al. (1990) to conclude that changes in social contact between monozygotic cotwins precede (and causally contribute to) changes in their intrapair similarity (p. 9). If true, this conclusion has important theoretical implications, e.g., many heritability estimates would have to be revised downward. We adduce evidence suggesting that similarity leads to contact, rather than the other way around. Low correlations between twins' frequency of contact and their absolute within-pair difference on all traits thus far studied indicates that, whichever the direction of causality, the relationship between MZ within-pair similarity and their frequency of contact is very weak.This work was supported in part by Grant 2 RO1 MH37860-06 from the National Institute of Mental Health in support of the Minnesota Twin Registry.Richard Rose, Jaakko Kapno, and Christopher Williams will be replying to this paper in a subsequent issue.     

Is lead exposure the principal cause of essential hypertension?

Lead is a ubiquitous toxin, known to have adverse effects on the body even at low levels of exposure. In this review we explore whether low lead may be the principal or a major contributory cause of essential hypertension, and whether removal of lead from the environment may eventually reduce both the overall incidence of hypertension and the increased incidence with aging.     

Does airway hyperresponsiveness monitoring lead to improved asthma control?

The current guidelines recommend an approach to asthma management based on asthma control, rather than asthma severity. Although several specific questionnaires have been developed and control criteria have been established based on clinical guidelines, the evaluation of asthma control is still not optimal. In general, these indicators provide adequate assessment of current control, but they are more limited when estimating future risk. There is much evidence demonstrating the persistence of airway inflammation and airway hyperresponsiveness (AHR) in patients with total control. Therefore, the objective of this review was to analyse the possible role of AHR monitoring as an instrument for assessing asthma control. We will evaluate its capacity as an indicator for future risk, both for estimating the possibility of clinical deterioration and loss of lung function or exacerbations. Furthermore, its relationship with inhaled corticosteroid treatment will be analysed, while emphasizing its capacity for predicting response and adjusting dosage, as well as information about the capability of AHR for monitoring treatment. Last of all, we will discuss the main limitations and emerging opportunities of AHR as an assessment instrument for asthma control.     

Does dose reduction of renally cleared antibiotics in patients with impaired renal function lead to adequate drug exposure? A systematic review

BackgroundThere is inconsistency between many guidelines in the recommended dose reduction of renally cleared antibiotics in patients with impaired renal function.ObjectivesThis systematic review summarizes the available evidence on the adequacy of the recommended dose reduction in terms of achieving sufficient antibiotic drug exposure or pharmacokinetic/pharmacodynamic target attainment after treatment with these reduced doses.Data sourcesWe systematically searched Ovid Medline and Embase from inception (respectively 1946 and 1947) through July 2019.Study eligibility criteriaAll studies reporting antibiotic drug exposure and/or pharmacokinetic/pharmacodynamic (PK/PD) target attainment after dose reduction of antibiotics in patients with impaired renal function.ParticipantsAdult patients with or without infections.InterventionsAdministration of reduced doses of antibiotics (orally, intravenously or intramuscularly).MethodsThe reduced dose was considered adequate when the most relevant parameters of drug exposure or PK/PD target attainment in patients with impaired renal function were within a range of 80% to 125% of that patients with adequate renal function receiving a regular dose (reference) or when PK/PD target attainment was attained in at least 90% of the patients with impaired renal function, regardless of the lack of a reference group.ResultsTwenty-seven of the 4202 identified studies were included. The quality of 15 of 27 studies was fair, and most studies were of β-lactams (12/27). Best evidence was available for meropenem: four studies were included, of which two studies were of good quality. Drug exposure for meropenem is 158% to 286% higher in patients with impaired renal function receiving reduced doses compared to patients with adequate renal function receiving regular doses. For all other antibiotics, a maximum of one good-quality study could be identified.ConclusionsNo good-quality evidence on the recommended dose reduction of renally cleared antibiotics in patients with impaired renal function is present, with the exception of meropenem.     

Does the contribution of stimulus-hand correspondence to the auditory Simon effect increase with practice?

In two-choice reaction tasks for which stimulus location is irrelevant, crossing the hands typically does not alter the benefit for corresponding stimulus and response locations (the Simon effect), which implies location coding of responses. However, for auditory tasks in which a consistent mapping between responding hand and tone pitch is maintained, the Simon effect may become smaller for crossed than uncrossed hands with practice, suggesting increased reliance on anatomical coding. Two experiments tested this possibility. In Exp. 1, the Simon effect tended to be smaller with crossed than uncrossed hands in the second half of 1,600 trials but not in the first half. Experiment 2 showed that this result was not due to reinstructing subjects mid-experiment about the consistent mapping of stimuli to hands. Although the Simon effect was apparent with crossed hands throughout both experiments, it tended to be slightly smaller than the effect obtained with uncrossed hands.     

Does maternal smoking increase the risk of neonatal polycythaemia?

The objective of this observational study was to determine the relationship between tobacco smoking during pregnancy and neonatal Polycythaemia, and to assess the dose-response relationship. Thirty two pregnant women who smoked tobacco (cases), and ninety pregnant women who did not smoke (controls), were randomly selected from the annual obstetrics population in the Erinville hospital in Cork. This study was carried out over eighteen months and the subjects were seen three times, at 28, 32, and 36 weeks gestation. At each visit, a smokalyser test was preformed and the results were recorded. The subjects were also given charts to fill in the number of cigarettes they smoked each day for the four week period. Nicotine consumption milligrams per day was calculated depending on the brand they smoked. Finally, at labour, cord blood samples were obtained and sent for haemoglobin and haematocrit estimation. At the end of the study it was found that both cord blood haemoglobin and haematocrit were statistically significantly higher in smoking mothers, p < 0.01 and p < 0.001 respectively. The dose-response relationship was also statistically significant.     

Does adoption of an evidence-based practice lead to job turnover? Results from a randomized trial

It is important to understand the impact of implementation of evidence-based practices (EBPs) on the workforce. EBP implementation can increase job demands, stress, and burnout, and may thereby exacerbate turnover. This study examined the effects of implementation of an EBP on turnover among staff at nine child welfare agencies. A total of 102 providers were randomized to either adopt an EBP, SafeCare^©, or continue providing services as usual. Participants completed a baseline survey assessing demographics, attitudes toward EBPs, and organizational functioning, and provider turnover was recorded for up to 18 months following implementation. The overall turnover rate was 35%, but did not differ by EBP assignment (odds ratio [OR] = 1.27; 95% confidence interval [0.66, 2.45]). Variables associated with turnover included age (OR = 0.92), years since degree completion (OR = 0.94), prior exposure to EBP (OR = 3.91), believing that adopting an EBP was burdensome (OR = 0.52), and motivation for change (OR = 0.89). EBP assignment moderated two aspects of negative attitudes toward EBP (divergence and monitoring) to predict turnover; those attitudes were only positively related to turnover for individuals assigned to the EBP (OR = 1.46, 1.16). Implications of the findings for implementation are discussed.     

Does the progression of myocardial fibrosis lead to atrial fibrillation in patients with hypertrophic cardiomyopathy?

The majority of left ventricular (LV) inflow volumes in hypertrophic cardiomyopathy (HCM) depend on atrial contraction because of impaired LV relaxation. If HCM is complicated by atrial fibrillation (AF), heart failure can develop because of the loss of atrial contraction. The purpose of this study was to determine the relationship between the development of AF and myocardial fibrosis or intramyocardial small artery (IMSA) stenosis in autopsied hearts with HCM. Studies were performed in five HCM hearts with AF (AF group) and five HCM hearts without AF (non-AF group). LV specimens were divided into the inner (IT), middle (MT), and outer (OT) thirds. We selected at random 120 fields and 20 IMSAs from each layer and assessed them quantitatively using an image analyzer. We determined the extent of fibrosis (%F) and the degree of stenosis of each IMSA (%L). The %F in the AF group was greater than in the non-AF group (P<.01). In the AF group, the %F of the IT was greater than in the MT and the OT (P<.01). In the non-AF group, the %F of the IT was greater than in the MT (P<.05), and the %F of the MT was greater than in the OT (P<.01). The %L was similar in the AF and non-AF groups. In both groups, the %L of the IT was lower than in the MT (P<.01), which was lower than that of the OT (P<.05). LV fibrosis is more severe in patients with HCM and AF than in those without AF. Therefore, myocardial fibrosis might impair LV relaxation, resulting in hemodynamic intolerance to AF.     

Does cigarette smoke exposure lead to histopathological alterations in the olfactory epithelium? An electron microscopic study on a rat model

Objective: This study was conducted to examine the influence of smoke exposure of variable duration on the ultrastructure of and histopathologic and morphologic alterations in the olfactory epithelium.

Methods: A total of 24 Wistar albino rats were randomly assigned to three groups and fed a standard rat chow and tap water. Experimental rats in groups I and II were exposed to cigarette smoke in a glass cabin over a period of 2 months for 5 or 15 min, respectively, four times daily; control rats (group III) were not exposed to cigarette smoke. After dissection, all tissue specimens were processed using routine procedures for TEM.

Results: Groups I and II exhibited the presence of intraepithelial inflammatory cells and especially deep invaginations in the nuclear membrane of supporting cells. Extended intercellular spaces, cytoplasmic protrusions on the apical surface of supporting cells, atrophy of microvilli and olfactory neuron cilia as well as numerous electron-dense granular structures and lysosome-like structures were observed to an increasing degree from group I to group II. Particularly in group II, both supporting cells and olfactory neurons exhibited a cytoplasmic edema, mitochondrial degeneration, and numerous vacuolar structures, as well as apoptotic and minimal necrotic changes. In this group, hyperplasia of basal cells was also observed.

Conclusion: Our electron microscopic findings show that cigarette smoke leads to toxic degenerative changes in the rat olfactory mucosa.