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Biomedical subjects

B Lo

Publications and source records attributed to B Lo.

At least 37 records · Page 2Linked to original sources
PubMed2000

The effect of coffee on gastric emptying and oro-caecal transit time.

BACKGROUND: The consumption of coffee allegedly induces or aggravates gastrointestinal symptoms. In order to investigate the effect of coffee on gastrointestinal motility we studied the effect of coffee on gastric emptying and oro-caecal transit time. METHODS: In a randomised, controlled, cross-over study gastric emptying and oro-caecal transit time were studied in 12 healthy volunteers, using applied potential tomography and lactulose hydrogen breath test, respectively. After 1 day of coffee abstinence and an overnight fast, coffee or the control drink (water) was drunk and 10 min thereafter a liquid nutrient meal was ingested together with lactulose. During 150 min, recordings were made with applied potential tomography and breath samples were taken every 5 min. Lag-phase duration and gastric half-emptying time were determined by two blinded observers. RESULTS: The lag-phase duration after coffee (median 19.8 min, range 6-47 min) was not significantly different from that after water (median 19.3 min, range 11-37.5), nor was the gastric half-emptying time (median 75.7 min, range 56-157.6 vs. median 83.4 min, range 64. 6-148.4). Likewise, coffee had no significant effect on oro-caecal transit time (median 135 min, range 60-270 vs. median 140 min, range 55-270). No significant correlation between any of these parameters and mean daily coffee intake was found. CONCLUSIONS: Coffee does not affect gastric emptying of a liquid meal or small bowel transit.

Adult↗
PubMed1999

Resolving disagreements in the patient-physician relationship: tools for improving communication in managed care.

Managed care uses financial incentives and restrictions on tests and procedures to attempt to influence physician decision making and limit costs. Increasingly, the public is questioning whether physicians are truly making decisions based on the patient's best interest or are unduly influenced by economic incentives. These circumstances lead to the potential for disagreements and conflict in the patient-physician relationship. We convened a group of individuals in October 1998, including patient representatives, leaders from health care organizations, practicing physicians, communication experts, and medical ethicists, to articulate the types of disagreements emerging in the patient-physician relationship as a result of managed care. We addressed 3 specific scenarios physicians may encounter, including allocation, illustrated by a patient who is referred to a different ophthalmologist based on a new arrangement in the physician's group; access, illustrated by a patient who wishes to see his own physician for a same-day visit rather than a nurse specialist; and financial incentives, illustrated by a patient who expects to have a test performed and a physician who does not believe the test is necessary but is afraid the patient will think the physician is not ordering the test because of financial incentives. Using these scenarios, we suggest communication strategies that physicians can use to decrease the potential for disagreements. In addition, we propose strategies that health plans or physician groups can use to alleviate or resolve these disagreements.

Communication↗
PubMed1999

Primary care physicians should be coordinators, not gatekeepers.

Primary care gatekeeping, in which the goal of the primary care physician (PCP) is to reduce patient referrals to specialists and thereby reduce costs, is not an adequate system in which to practice medicine. However, returning to the pre-managed care model of uncoordinated open access to specialists is a poor solution. The primary care model should be retained, but PCPs should be transformed from gatekeepers into coordinators of care, in which the goal of the PCP is to integrate both primary and specialty care to improve quality. Changes in the PCP's daily work process, as well as the referral and payment processes, need to be implemented to reach this goal. This model would eliminate the requirement that referrals to specialists be authorized by the primary care physician or managed care organization. Financial incentives would be needed, eg, to encourage PCPs to provide management of complex cases and discourage both over-referral and underreferral to specialists. Budgeting specialists should control excess costs that might be created by the elimination of the primary care gatekeeper. Pilot projects are needed to test and refine this model of PCP as coordinator of care.

Case Management↗
PubMed1999

Effect of incentives on the use of indicated services in managed care.

In managed care, financial incentives and utilization review create conflicts of interest for physicians. We sought to determine whether these incentives would lead physicians to deny indicated services. We surveyed internists practicing in areas with at least 30% penetration of managed care. Our questionnaire included four scenarios in which a test or referral is indicated according to clearly established practice guidelines. We randomly assigned physicians to receive one of five versions of the questionnaire, which differed only in the type of reimbursement incentive and utilization review that applied to the scenarios. We received responses from 710 (70%) of 1,009 internists. Although physicians underutilized services regardless of incentives in all scenarios, physicians whose questionnaires depicted full capitation said that they would order fewer services than physicians whose questionnaires depicted fee-for-service. In the scenario in which an x-ray of the lumbosacral spine is indicated for a patient with low back pain, 86% of physicians randomized to the full capitation version said that they would order the test compared to 94% in the fee-for-service version. Similarly, physicians randomized to scenarios requiring utilization review said that they would order fewer services than those randomized to scenarios requiring completion of an insurance form. Scenarios depicting managed care incentives caused consistent, modest underutilization compared to fee-for-service scenarioes, although physicians underutilized services under all financial incentives and utilization review. In response, physicians must develop better methods for detecting underutilization and devise programs to increase the provision of indicated services.

Adult↗
PubMed1998

Postexposure prophylaxis after nonoccupational HIV exposure: clinical, ethical, and policy considerations.

In the wake of recent breakthroughs in antiviral therapies and Centers for Disease Control and Prevention (CDC) recommendations advocating occupational postexposure prophylaxis (PEP), health care workers are increasingly receiving inquiries about PEP following exposures to the human immunodeficiency virus (HIV) through sex and injection drug use. The probability of HIV transmission by certain sexual or injection drug exposures is of the same order of magnitude as percutaneous occupational exposures for which the CDC recommends PEP. In such cases, if the exposure is sporadic, it seems appropriate to extrapolate from the data on occupational PEP and recommend prophylaxis. However, for individuals with continuing or low-risk exposures, we instead recommend referrals to state-of-the-art risk reduction programs. Clinicians, using local HIV seroprevalence data and their knowledge of transmission probabilities, can help exposed patients make an informed decision regarding PEP. Because of the large number of risky encounters that will not be treated prophylactically, even after significant outreach efforts, public health interventions that emphasize PEP as part of a comprehensive HIV prevention program should be confined to cities with highest HIV prevalences.

Anti-HIV Agents↗
PubMed1998

Cysteine scanning mutagenesis of the segment between putative transmembrane helices IV and V of the high affinity Na+/Glucose cotransporter SGLT1. Evidence that this region participates in the Na+ and voltage dependence of the transporter.

Site-directed mutagenesis and chemical modification of specific cysteine amino acid side chains by methanethiosulfonate (MTS) derivatives were combined to elucidate structure/function relationships of the cloned rabbit Na+/glucose cotransporter, SGLT1. Each amino acid in the region (residues 162-173) between putative transmembrane helices IV and V of SGLT1 was replaced individually with Cys. Mutant proteins were expressed in Xenopus laevis oocytes and studied using the two-electrode voltage clamp method. At certain key positions, Cys substitution resulted in 1) a change in the apparent affinity for sugar, 2) an alteration in the voltage dependence of the transient currents, and 3) a sensitivity to inhibition by either the ethylamine (MTSEA) or the ethylsulfonate MTS derivatives. For the three Cys mutants inhibited by MTSEA (F163C, A166C, and L173C), inhibition of steady state transport is related to changes in membrane potential-dependent transitions within the Na+/glucose transport cycle. MTSEA shifted the transient currents of these Cys mutants toward more negative membrane potentials (DeltaV0. 5 = -18 mV for F163C and A166C, -12 mV for L173C). When the mutations were combined to produce double and triple Cys mutants, the degree to which the transient currents were shifted along the membrane potential axis by MTSEA correlated with the number of cysteines. In this way it was possible to manipulate the voltage dependence of the transient currents over a range spanning 91 mV. Examination of the Na+ dependence of the transient currents indicates that a 91-mV shift is equivalent to that caused by a 10-fold reduction in the external Na+ concentration. We conclude that this region has a role in determining the Na+ binding- and voltage-sensing properties of SGLT1 and that it forms an alpha-helix with one surface possibly lining a Na+ pore within SGLT1.

Amino Acid Sequence↗
PubMed1998

Functional studies of the rabbit intestinal Na+/glucose carrier (SGLT1) expressed in COS-7 cells: evaluation of the mutant A166C indicates this region is important for Na+-activation of the carrier.

We have exploited two mutants of the rabbit intestinal Na+/glucose carrier SGLT1 to explore the structure/function relationship of this Na+/glucose transporter in COS-7 cells. A functional N-terminal myc-epitope-tagged SGLT1 protein was constructed and used to determine the plasma-membrane localization of SGLT1. The kinetic and specificity characteristics of the myc-tagged SGLT1 mutant were identical with those of wild-type SGLT1. Immunogold labelling and electron microscopy confirmed the topology of the N-terminal region to be extracellular. Expression of the SGLT1 A166C mutant in these cells showed diminished levels of Na+-dependent alpha-methyl-d-glucopyranoside transport activity compared with wild-type SGLT1. For SGLT1 A166C, Vmax was 0.92+/-0.08 nmol/min per mg of protein and Km was 0.98+/-0.13 mM; for wild-type SGLT1, Vmax was 1.98+/-0.47 nmol/min per mg of protein and Km was 0.36+/-0.16 mM. Significantly, phlorrhizin (phloridzin) binding experiments confirmed equal expression of Na+-dependent high-affinity phlorrhizin binding to COS-7 cells expressing SGLT1 A166C or wild-type SGLT1 (Bmax 1.55+/-0.18 and 1.69+/-0.57 pmol/mg of protein respectively); Kd values were 0.46+/-0.15 and 0.51+/-0.11 microM for SGLT1 A166C and wild-type SGLT1 respectively. The specificity of sugar interaction was unchanged by the A166C mutation. We conclude that the replacement of an alanine residue by cysteine at position 166 has a profound effect on transporter function, resulting in a decrease in transporter turnover rate by a factor of 2. Taken as a whole the functional changes observed by SGLT1 A166C are most consistent with the mutation having caused an altered Na+ interaction with the transporter.

Animals↗
PubMed1998

Replacement of Ala-166 with cysteine in the high affinity rabbit sodium/glucose transporter alters transport kinetics and allows methanethiosulfonate ethylamine to inhibit transporter function.

An alanine to cysteine mutation at position 166 has been introduced by site-directed mutagenesis into the rabbit sodium/glucose transporter (rSGLT1). When expressed in Xenopus laevis oocytes, this mutant transporter (A166C rSGLT1) demonstrates a significantly lower apparent affinity for alpha-methyl glucoside (alphaMG) compared with the wild-type transporter (apparent Km = 0.8 versus 0.15 mM). Using the two-electrode voltage clamp technique, transient currents have also been measured, and for the mutant transporter, the transients induced by large depolarizations exhibit longer time constants than those for wild type. Moreover, the substitution of Ala-166 with a cysteine allows the sulfydryl specific reagent, methanethiosulfonate ethylamine (MTSEA), to react with and alter the function of the transporter. Whereas the wild-type transporter is unaffected by reaction with MTSEA, A166C rSGLT1 has its steady-state currents induced by 1 mM alphaMG inhibited 83% within a minute of exposure to MTSEA. Furthermore, the pre-steady-state transients of the A166C mutant after MTSEA exposure demonstrate much shorter time constants than before while the total amount of charge transferred is only slightly diminished. These results together provide evidence that position 166 is situated in a region critical to the functioning of rSGLT1.

Alanine↗
PubMed1998

Health Care Financing Administration's new regulations for financial incentives in Medicaid and Medicare managed care: one step forward?

Because financial incentives for managed care physicians may create conflicts of interests, new regulations have been instituted that will result in disclosure of certain financial incentives to the Federal Government and to some patients. Given the limitations of these regulations, health plans and physicians should take the lead in addressing concerns about the harmful effects of financial incentives. For example, public disclosure may deter unusually strong financial incentives. Purchasing coalitions, advocacy groups, and journalists should have increased access to information about physician-level incentives. These nonregulatory measures might reassure patients that managed care physicians are committed to their best interests.

Centers for Medicare and Medicaid Services, U.S.↗
PubMed1998

What hysterectomy [corrected] patients want to know about the roles of residents and medical students in their care.

PURPOSE: To determine what patients want to know regarding the participation of trainees in their care. METHOD: In 1995, questionnaires were sent to 111 women who had undergone elective hysterectomies between September 1992 and June 1994 at two teaching hospitals at the University of California, San Francisco, School of Medicine. The questionnaires asked the women about their awareness of and attitudes toward the participation of residents and medical students in their care and about how they thought physicians should communicate information regarding residents to patients. RESULTS: Fifty-nine women (68%) returned the questionnaire. Thirty-seven of them (63%) knew that a resident had been involved in their care. Eighty percent of the respondents felt it important to know how residents were supervised and what they would do during the operation. Nearly half did not know whether a medical student had been involved in their care. Over 90% agreed that the attending gynecologist should tell patients that a resident would participate in the operation as well as what the resident would do. Most believed that residents are adequately supervised and that medical students have time to provide more attention to patients. CONCLUSIONS: Most of the women wanted to know about the participation and specific roles of residents and students. Attending physicians should take the initiative to talk with patients about the roles of trainees. Open discussions can promote patient autonomy, maintain public confidence in academic health institutions, and benefit future patients.

Attitude to Health↗
PubMed1997

Palliative options of last resort: a comparison of voluntarily stopping eating and drinking, terminal sedation, physician-assisted suicide, and voluntary active euthanasia.

Palliative care is generally agreed to be the standard of care for the dying, but there remain some patients for whom intolerable suffering persists. In the face of ethical and legal controversy about the acceptability of physician-assisted suicide and voluntary active euthanasia, voluntarily stopping eating and drinking and terminal sedation have been proposed as ethically superior responses of last resort that do not require changes in professional standards or the law. The clinical and ethical differences and similarities between these 4 practices are critically compared in light of the doctrine of double effect, the active/passive distinction, patient voluntariness, proportionality between risks and benefits, and the physician's potential conflict of duties. Terminal sedation and voluntarily stopping eating and drinking would allow clinicians to remain responsive to a wide range of patient suffering, but they are ethically and clinically more complex and closer to physician-assisted suicide and voluntary active euthanasia than is ordinarily acknowledged. Safeguards are presented for any medical action that may hasten death, including determining that palliative care is ineffective, obtaining informed consent, ensuring diagnostic and prognostic clarity, obtaining an independent second opinion, and implementing reporting and monitoring processes. Explicit public policy about which of these practices are permissible would reassure the many patients who fear a bad death in their future and allow for a predictable response for the few whose suffering becomes intolerable in spite of optimal palliative care.

Beneficence↗