Local adaptation from afar: migratory bird populations diverge in the initiation of reproductive timing while wintering in sympatry.

The initiation of reproduction in many seasonally breeding animals is controlled by photoperiod and tends to be clinal: populations at higher latitudes breed later than those at lower latitudes, often reflecting a higher photoperiodic threshold. Migratory animals presumably time reproduction to match conditions at their breeding grounds, at least in part, by cues perceived on their wintering grounds. We asked how closely related dark-eyed junco (Junco hyemalis) populations that overwinter in sympatry but breed in allopatry respond to their shared winter environment by comparing early spring indices of readiness to migrate (fat and muscle condition) and breed (baseline and elevated testosterone). We measured stable hydrogen isotopes from feathers grown the preceding year and claws grown during winter to estimate breeding and wintering latitudes, respectively. We predicted that if reproductive initiation is adapted to the emergence of resources at their respective breeding destinations, then birds migrating to higher latitudes (slate-coloured junco; J. h. hyemalis) should delay breeding as compared with those migrating to lower latitudes (pink-sided junco; J. h. mearnsi) despite a common overwinter environment. We found higher testosterone in pink-sided juncos, consistent with earlier reproductive initiation, suggesting local adaptation in reproductive phenology is achieved through differential responses to predictive environmental cues.

The relationship of insulin resistance measured by reliable indexes to coronary artery disease risk factors and outcomes--a systematic review.

OBJECTIVES: To provide a qualitative and quantitative review of the published literature that examines the relationship between reliable markers of insulin resistance and coronary artery disease risk factors (plasma glucose, triglycerides, high density lipoprotein cholesterol, hypertension, obesity, low density lipoprotein size) and outcomes (as related to ischemic heart disease) in populations with and without type 2 diabetes. METHODS: The MEDLINE database was searched (January 1966 to April 2000). Additional references were identified from bibliographies of retrieved articles. The quantitative relationship between insulin resistance and coronary artery disease outcomes was estimated in individual studies by derivation of 2x2 tables. RESULTS: Of 780 publications reviewed, 28 met the inclusion criteria. Twenty publications investigated the relationship of insulin resistance markers with coronary artery disease risk factor profiles only, while eight publications primarily evaluated coronary artery disease outcomes. CONCLUSIONS: The present review suggests that populations with lower insulin resistance measured by reliable indexes are consistently associated with better overall cardiovascular risk profiles (including reduced clustering of risk factors), and improved coronary artery disease outcomes than populations with elevated insulin resistance.

Moderate to heavy caffeine consumption during pregnancy and relationship to spontaneous abortion and abnormal fetal growth: a meta-analysis.

The objective was to determine the association of moderate to heavy caffeine consumption during pregnancy on spontaneous abortion and birth weight in humans. Data sources used included a computerized literature search of MEDLINE (1966-July 1996); EMBASE (1988-November 1996); Psychlit I (1974-1986); Psychlit II (1987-1996); CINAHL (1982-May 1996) and manual search of bibliographies of pertinent articles. Inclusion criteria were: English language research articles; pregnant human females; case control or cohort design; documented quantity of caffeine consumption during pregnancy; control group with minimal or no caffeine consumption (0 to 150 mg caffeine/d); documented data regarding spontaneous abortion and/or fetal growth. The exclusion criteria were: case reports; editorials; review papers. The methods section of each study was examined independently by two blinded investigators with a third investigator adjudicating disagreements. Two independent investigators extracted data onto a standardized form. A third investigator adjudicated discrepancies. We compared a caffeine-exposed group (>150 mg/d) and controls (0 to 150 mg/d), using Mantel-Haenszel pooling. Of the 32 studies meeting inclusion criteria, 12 had extractable data (6 for spontaneous abortion, 7 for low birth weight, 1 common study). Mantel-Haenszel odds ratio (CI95%) was 1.36 (1.29-1.45) for spontaneous abortion in 42,988 pregnancies. The overall risk ratio was 1.51 (1.39-1.63) for low birthweight (<2500 g) in 64,268 pregnancies. Control for confounders such as maternal age, smoking, and ethanol use was not possible. We concluded that there is a small but statistically significant increase in the risks for spontaneous abortion and low birthweight babies in pregnant women consuming >150 mg caffeine per d. A possible contribution to these results of maternal age, smoking, ethanol use, or other confounders could not be excluded.

The cricopharyngeal sphincter in gastric reflux.

This study was prompted by a clinical association noted between reflux oesophagitis and upper oesophageal disorders. Patients with reflux oesophagitis have been shown to have a significantly raised resting cricopharyngeal pressure. Patients with reflux oesophagitis (36%) complaining of dysphagia localized to the throat also had a high resting cricopharyngeal pressure. Successful repair of a hiatus hernia restored the cricopharyngeal pressure to within the normal range. Four of the five patients studied who had a pharyngeal pouch also had a raised cricopharyngeal pressure.