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The purpose of this study was to explore caffeine intake habits and the perception of its effects on health among college students. After completing a literature review on the topic of caffeine and its effects, a problem was identified relating to increased caffeine consumption and a gap in knowledge about the effects of caffeine among college students. This was a quantitative, cross-sectional study with a descriptive design. The participants were 120 college students in a campus population of about 2000 in Northern Indiana. The survey contained five demographic and 19 Likert-type statements on a 4-point scale of (1) "strongly disagree," (2) "disagree," (3) "agree," and (4) "strongly agree." Data collection occurred on the college campus at the sandwich shop, during the lunch hour. In the perception category, "Regularly consuming caffeine can have long-term negative effects on health" (mean [SD], 3.10 [0.68]) received the highest agreement. In the habit category, "I drink caffeinated beverages because I like the taste" (mean [SD], 3.11 [0.85]) received the highest agreement. In conclusion, college students are aware of the negative effects of caffeine, yet 75% consumed one or more and some exceeding five servings daily.

Morphogenesis of the semicircular canal ducts in the vertebrate inner ear is a dramatic example of epithelial remodelling in the embryo, and failure of normal canal development results in vestibular dysfunction. In zebrafish and Xenopus, semicircular canal ducts develop when projections of epithelium, driven by extracellular matrix production, push into the otic vesicle and fuse to form pillars. We show that in the zebrafish, extracellular matrix gene expression is high during projection outgrowth and then rapidly downregulated after fusion. Enzymatic disruption of hyaluronan in the projections leads to their collapse and a failure to form pillars: as a result, the ears swell. We have cloned a zebrafish mutant, lauscher (lau), identified by its swollen ear phenotype. The primary defect in the ear is abnormal projection outgrowth and a failure of fusion to form the semicircular canal pillars. Otic expression of extracellular matrix components is highly disrupted: several genes fail to become downregulated and remain expressed at abnormally high levels into late larval stages. The lau mutations disrupt gpr126, an adhesion class G protein-coupled receptor gene. Expression of gpr126 is similar to that of sox10, an ear and neural crest marker, and is partially dependent on sox10 activity. Fusion of canal projections and downregulation of otic versican expression in a hypomorphic lau allele can be restored by cAMP agonists. We propose that Gpr126 acts through a cAMP-mediated pathway to control the outgrowth and adhesion of canal projections in the zebrafish ear via the regulation of extracellular matrix gene expression.

Pulsed field gradient NMR is a well-established technique for the determination of self-diffusion coefficients. However, a significant source of systematic error exists in the spatial variation of the applied pulsed field gradient. Non-uniform pulsed field gradients cause the decay of peak amplitudes to deviate from the expected exponential dependence on gradient squared. This has two undesirable effects: the apparent diffusion coefficient will deviate from the true value to an extent determined by the choice of experimental parameters, and the error estimated by the nonlinear least squares fitting will contain a significant systematic contribution. In particular, the apparent diffusion coefficient determined by exponential fitting of the diffusional attenuation of NMR signals will depend both on the exact pulse widths used and on the range of gradient amplitudes chosen. These problems can be partially compensated for if experimental attenuation data are fitted to a function corrected for the measured spatial dependence of the gradient and signal strength. This study describes a general alternative to existing methods for the calibration of NMR diffusion measurements. The dominant longitudinal variation of the pulsed field gradient amplitude and the signal strength are mapped by measuring pulsed field gradient echoes in the presence of a weak read gradient. These data are then used to construct a predicted signal decay function for the whole sample, which is parameterised as the exponential of a power series. Results are presented which compare diffusion coefficients obtained using the new calibration method with previous literature values.

Solid-state carbon-13 (13C) and nitrogen-15 (15N) nuclear magnetic resonance (NMR) have been used to investigate how water interacts with sildenafil citrate. When the humidity is altered, the water concentration in the solid compound changes in a reversible manner. The proportion of occupied sites depends on the humidity, but the water concentration never reaches a rational (e.g., 1:1) stoichiometric ratio to form a true hydrate. The NMR spectra were obtained under several humidity-controlled conditions to determine what changes occur as the water content is varied and where the water is located in the crystal structure. Only one set of 15N and 13C signals is observed for each humidity level. This shows that water incorporated into the crystal lattice of sildenafil citrate is very mobile and exchanges rapidly on the NMR time scale between various sites. The 13C data are consistent with formation of a hydrogen bond between a water molecule and one carbonyl of the citrate anion. The spectra also show that the water content affects the environment (perhaps influencing the average conformation) of the propyl group. Additionally, 15N dipolar dephasing experiments show that the sildenafil molecule is only protonated in the piperazine ring. The work is supported by solution-state NMR., (Copyright 2004 Wiley-Liss, Inc. and the American Pharmacists Association.)

Stability and reproducibility of the spectrometer are fundamental to the success of many modern NMR experiments. Variation in room temperature is a particularly important source of instability, in part because it can cause coherent artifacts in NMR spectra. Small changes in room temperature lead to corresponding changes in the phases, amplitudes, and frequencies of NMR signals. These can lead in turn to apparently random spectral artifacts such as t(1)-noise in two-dimensional (2D) NMR and to the incomplete cancellation of signals in difference spectra, but also, importantly, to F(1) satellite signals in 2D spectra. These "parallel diagonals" arise from the use of air conditioning, which typically forces room temperature to oscillate within a fixed band. Work to identify, quantify, and suppress sources of temperature sensitivity in a modern 300-MHz spectrometer has led to a greater than 10-fold improvement in the signal-to-artifact ratio., (Copyright 2001 Academic Press.)

2D spectra, particularly for homonuclear correlation, can show a variety of artifactual signals in the F1 domain. Common sources include carry-over of signal modulation from one transient to the next ("rapid pulsing artifacts") and systematic variations in room temperature ("parallel diagonals"). In both cases there is one very simple expedient which can greatly reduce the impact of these sources of error. Multidimensional data sets are almost invariably recorded by simply incrementing or decrementing evolution periods, largely for reasons of convenience and historical precedent. If instead the sampling of the evolution periods is carried out in random order, the perturbations responsible for the sharp F1 signals in the conventional experiment manifest themselves as t1 noise. Since the randomized acquisition redistributes coherent artifactual signals randomly in F1, the maximum artifactual signal is substantially reduced in the randomized experiment and no longer appears in the form of misleading distinct peaks., (Copyright 1999 Academic Press.)

A three-dimensional experiment is described in which NMR signals are separated according to their proton chemical shift, 13C chemical shift, and diffusion coefficient. The sequence is built up from a stimulated echo sequence with bipolar field gradient pulses and a conventional decoupled HMQC sequence. Results are presented for a model mixture of quinine, camphene, and geraniol in deuteriomethanol. Copyright 1998 Academic Press.

High performance liquid chromatography has been coupled simultaneously to high field NMR and MS detectors, giving UV, NMR and mass spectra for each component in a mixture, after on-line separation. This powerful new tool for the structure elucidation of components in mixtures without isolation has been successfully applied to the analysis of the metabolites of paracetamol in human urine.

The earlier use of combined liquid chromatography/NMR spectrometry/mass spectrometry (LC/NMR/MS) involved the use of a particle beam interface. This paper describes further developments of this hyphenated technology, in particular the incorporation of an electrospray interface into the LC/NMR/MS system. This improved LC/NMR/MS system was designed for the support of a combinatorial library program. The power of this technique is demonstrated in the successful structural elucidation of each compound in a mixture of commercially available peptides.

Some NMR resonances which have previously been observed but not identified in mammalian brain tissue extracts have been shown to arise from ethanolamine. This conclusion is drawn from a systematic study of the perchloric acid extracts of rodent brain tissue in which several NMR experiments were used to assign the peaks unambiguously. The extraction procedure used in this work gave samples with highly reproducible spectra, and ethanolamine was observed in all our extract samples. A localized increase in the concentration of ethanolamine was seen in the spectra of extracts produced from a cerebral infarct induced by occlusion of the middle cerebral artery in the rat.

This essay begins with the history from 1989 through late 1991 of the Primary Care Organization's Consortium (PCOC), a group of representatives from nine major academic and professional organizations for primary care specialties. The PCOC was formed to discuss what might be done to reverse the alarming decrease in the number of medical students who choose primary care specialties. The article reviews some of the conditions that many believe have caused the continuing move away from primary care careers, and concludes with a description of the PCOC's program to encourage medical students to choose primary care careers, and the new opportunities for collaborative planning of such programs that are now available to medical schools. The PCOC's success in defining its program is due to a process of interdisciplinary planning and collaboration at the national level that hopefully will facilitate similar collaboration among medical school departments.

The medical curriculum at the University of Washington places considerable responsibility on the student in planning his education. This is provided for by assigning to elective courses 50 percent of the credits required for graduation. While the student has considerable freedom to choose among electives, as many credits are elected in the basic sciences as in the clinical disciplines. Four consecutive entering classes elected a disproportionately high number of credits in anatomy and pharmacology. A need for basic science courses in apparently perceived by the medical student, and their voluntary election is bound to facilitate learning. In new curricula the responsibility rests on the faculty to provide opportunities for detailed coverage of the various disciplines in order to cater to those students who are motivated to pursue them in greater depth.

In the early 1970s, affirmative-action programs were introduced to accomplish a number of social goals, including increasing the supply of minority physicians and improving the health care of the poor. To assess the success of such programs, we analyzed data on people who graduated from U.S. medical schools in 1975 to determine how specialty choice, practice locations, patient populations served, and board-certification rates differ between minority and nonminority graduates. A larger proportion of minority graduates (55 per cent vs. 41 per cent, P less than 0.001) chose the primary-care specialties of family practice, general internal medicine, general pediatrics, and obstetrics-gynecology. Significantly more minority physicians (12 per cent vs. 6 per cent, P less than 0.01) practiced in locations designated as health-manpower shortage areas by the federal government and had more Medicaid recipients in their patient populations (31 per cent for blacks, 24 per cent for Hispanics, 14 per cent for whites; P less than 0.001). Physicians from each racial or ethnic group served disproportionately more patients of their own racial or ethnic group (P less than 0.001), but minority physicians did not serve significantly more persons from other racial or ethnic minority groups than did nonminority physicians. Many minority physicians served patient populations much like those of their nonminority colleagues, which indicates that substantial integration of the medical marketplace has taken place. Significantly fewer minority graduates had become board-certified by 1984 (48 per cent vs. 80 per cent, P less than 0.001), and most of this disparity was associated with differences in premedical-school characteristics and in the patient populations they served. Our analysis shows that minority graduates of the medical school class of 1975 are fulfilling many of the objectives of affirmative-action programs.

A study was conducted that analyzed the relationship between various characteristics of the preclinical curriculum and institutional performance on the Part I examination of the National Board of Medical Examiners (NBME) at a sample of 85 U.S. medical schools. Total scheduled hours per week was the single curriculum characteristic having a positive and significant relationship with institutional NBME examination performance. However, when the data were controlled by medical school selectivity in admissions and institutional policy on the taking of the examination, total scheduled hours per week failed to make a significant contribution to the prediction of performance. The results were viewed as failing to provide support and justification for intense preclinical curriculum loads on the basis that this would enhance NBME examination performance. The authors conclude that simple comparisons of schools on the basis of mean NBME examination performance are meaningless unless the entering abilities of students and school policies on the examination are taken into account. The authors also suggest that those schools that prescribe heavy and intense preclinical curriculum loads should reexamine those policies in light of recommendations of the Project Panel on the General Professional Education of the Physician and College Preparation for Medicine.

To acquire information about the characteristics of U.S. citizens who had recently studied medicine abroad, the Educational Commission for Foreign Medical Graduates (ECFMG) and the Association of American Medical Colleges merged independently collected data on a study group of 10,460 U.S. citizens who attended 359 medical schools in 75 foreign countries and who took their first ECFMG examination between 1978 and 1982. The study group was markedly heterogeneous: 21 percent were not U.S. citizens at birth, 32 percent did not have English as a native language, and 12 percent had two or more years of undergraduate college education in Puerto Rico. Sixty-seven percent resided in New York, New Jersey, California, Florida, or Puerto Rico, and 74 percent studied medicine in Mexico or the Caribbean. Forty-six percent passed the ECFMG examination on their first attempt, and 22 percent passed a subsequent examination. Only 45 percent had applied to a U.S. medical school, and 65 percent had taken the Medical College Admission Test. The means of the college grade-point averages, known for 39 percent of the study group, and of the scores on the admission test, known for 65 percent, were lower than those of both accepted and unaccepted applicants to U.S. medical schools in the 1976 and 1978 entering classes. The finding that 55 percent of the study group did not apply to a U.S. medical school does not support the widely held belief that most, if not all, U.S. citizens who attend foreign medical schools do so only after several unsuccessful attempts to gain admission to a U.S. school.