Association between Decreased Estimated Glomerular Filtration Rates and Long-term Mortality in Korean Patients with Acute Myocardial Infarction

A reduced estimated glomerular filtration rate (eGFR) is a predictor for mortality in patients with acute myocardial infarction (AMI). This study aimed to compare mortality according to the GFR and eGFR calculation methods during long-term clinical follow-ups. Using the Korean Acute Myocardial Infarction Registry-National Institutes of Health Data, 13,021 patients with AMI were included in this study. Patients were divided into the surviving (n=11,503, 88.3%) and deceased (n=1,518, 11.7%) groups. Clinical characteristics, cardiovascular risk factors, and 3-year mortality-related factors were analyzed. eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Modification of Diet in Renal Disease (MDRD) equations. The surviving group was younger than the deceased group (62.6±12.4 vs. 73.6±10.5 years, p<0.001), whereas the deceased group had higher hypertension and diabetes prevalences than the surviving group. A high Killip class was more frequently observed in the deceased group. eGFR was significantly lower in the deceased group (82.2±24.1 vs. 55.2±28.6 ml/min/1.73 m², p<0.001). Multivariate analysis revealed that low eGFR was an independent risk factor for mortality during the 3-year follow-up. The CKD-EPI equation was more useful for predicting mortality than the MDRD equation (0.766; 95% confidence interval [CI], 0.753-0.779 vs. 0.738; 95% CI, 0.724-0.753; p=0.001). Decreased renal function was a significant predictor of mortality after 3 years in patients with AMI. The CKD-EPI equation was more useful for predicting mortality than the MDRD equation.

Facemask ventilation and vocal cord angle following neuromuscular blockade: a prospective observational study. Anaesthesia 2022;77:1010-1017. [PMID: 35727620 DOI: 10.1111/anae.15786]

Numerous studies support the idea that neuromuscular blockade facilitates facemask ventilation after induction of anaesthesia. Although improved airway patency or pulmonary compliance and a resolution of laryngospasm have been suggested as possible causes, the exact mechanism remains unclear. We aimed to assess whether neuromuscular blockade improves facemask ventilation and to clarify whether this phenomenon is associated with the vocal cord angle. This prospective observational study included patients aged between 20 and 65 years scheduled for elective surgery under general anaesthesia. After induction of anaesthesia, patients' lungs were ventilated with pressure-controlled ventilation using a facemask. During facemask ventilation, a flexible bronchoscope was inserted through a self-sealing diaphragm at the elbow connector attached to the facemask and breathing circuit and positioned to allow a continuous view of the vocal cords. The mean tidal volume and vocal cord angle were measured before and after administration of neuromuscular blocking drugs. Of 108 patients, 100 completed the study. Mean (SD) tidal volume ((11.0 (3.9) ml.kg^-1 vs. 13.6 (2.6) ml.kg^-1 ; p < 0.001) and mean (SD) vocal cord angle (17° (10°) vs. 26° (5°); p < 0.001) increased significantly after neuromuscular blockade. The proportional increase in mean tidal volume after neuromuscular blockade was positively correlated with vocal cord angle (Spearman's ρ = 0.803; p < 0.001). In conclusion, neuromuscular blockade facilitated facemask ventilation, and the improvement was correlated with further opening of the vocal cords.

Validity and Reliability of the Korean Version of the Revised Self-Care of Heart Failure Index v7.2

The psychometric properties of the Korean version of the revised Self-Care of Heart Failure Index (SCHFI) remain undetermined; therefore, we aimed to evaluate the construct and convergent validity and reliability of the Korean version of the SCHFI in Korean patients with heart failure (HF). Using a cross-sectional design, 207 patients with HF provided data on self-care and self-efficacy in self-care for this psychometric testing. The confirmatory factor analysis supported the construct validity of the Korean version with a three-factor structure: Self-Care Maintenance, Symptom Perception, and Self-Care Management. Convergent validity was supported by the significant relationships between self-efficacy and each scale of the Korean version of the SCHFI (r = .425-.549, p < .001). The reliability estimates were marginally adequate, with a Cronbach's alpha of .655 to .776, McDonald's omega of .710 to .836, and composite reliability coefficients of .704 to .834. The SCHFI was supported as a valid and reliable measure of self-care for Koreans with HF. However, the marginal levels of the Cronbach's alpha coefficients still require validation in a larger sample.

Association between time to treatment and functional outcomes according to the Diffusion-Weighted Imaging Alberta Stroke Program Early Computed Tomography Score in endovascular stroke therapy

BACKGROUND AND PURPOSE

The rate at which the chance of a good outcome of endovascular stroke therapy (EVT) decays with time when eligible patients are selected by baseline diffusion-weighted magnetic resonance imaging (DWI-MRI) and whether ischaemic core size affects this rate remain to be investigated.

METHODS

This study analyses a prospective multicentre registry of stroke patients treated with EVT based on pretreatment DWI-MRI that was categorized into three groups: small [Diffusion-Weighted Imaging Alberta Stroke Program Early Computed Tomography Score (DWI-ASPECTS)] (8-10), moderate (5-7) and large (<5) cores. The main outcome was a good outcome at 90 days (modified Rankin Scale 0-2). The interaction between onset-to-groin puncture time (OTP) and DWI-ASPECTS categories regarding functional outcomes was investigated.

RESULTS

Ultimately, 985 patients (age 69 ± 11 years; male 55%) were analysed. Potential interaction effects between the DWI-ASPECTS categories and OTP on a good outcome at 90 days were observed (P_interaction  = 0.06). Every 60-min delay in OTP was associated with a 16% reduced likelihood of a good outcome at 90 days amongst patients with large cores, although no associations were observed amongst patients with small to moderate cores. Interestingly, the adjusted rates of a good outcome at 90 days steeply declined between 65 and 213 min of OTP and then remained smooth throughout 24 h of OTP (P_nonlinearity  = 0.15).

CONCLUSIONS

Our study showed that the probability of a good outcome after EVT nonlinearly decreased, with a steeper decline at earlier OTP than at later OTP. Discrepant effects of OTP on functional outcomes by baseline DWI-ASPECTS categories were observed. Thus, different strategies for EVT based on time and ischaemic core size are warranted.

Activated leucocyte cell adhesion molecule (ALCAM/CD166) regulates T cell responses in a murine model of food allergy

Food allergy is a major public health problem. Studies have shown that long-term interactions between activated leucocyte cell adhesion molecule (ALCAM/CD166) on the surface of antigen-presenting cells, and CD6, a co-stimulatory molecule, influence immune responses. However, there are currently no studies on the functions of ALCAM in food allergy. Therefore, we aimed to identify the functions of ALCAM in ovalbumin (OVA)-induced food allergy using ALCAM-deficient mice. Wild-type (WT) and ALCAM-deficient (ALCAM^-/- ) mice were sensitized intraperitoneally and with orally fed OVA. The mice were killed, and parameters related to food allergy and T helper type 2 (Th2) immune responses were analysed. ALCAM serum levels increased and mRNA expression decreased in OVA-challenged WT mice. Serum immunoglobulin (Ig)E levels, Th2 cytokine mRNA and histological injuries were higher in OVA-challenged WT mice than in control mice, and these were attenuated in ALCAM^-/- mice. T cell proliferation of total cells, CD3⁺ CD4⁺ T cells and activated T cells in immune tissues were diminished in OVA-challenged ALCAM^-/- mice. Proliferation of co-cultured T cells and dendritic cells (DCs) was decreased by the anti-CD6 antibody. In addition, WT mice sensitized by adoptive transfer of OVA-pulsed ALCAM^-/- BM-derived DCs showed reduced immune responses. Lastly, serum ALCAM levels were higher in children with food allergy than in control subjects. In this study, serum levels of ALCAM were elevated in food allergy-induced WT mice and children with food allergy. Moreover, immune responses and T cell activation were attenuated in OVA-challenged ALCAM^-/- mice. These results indicate that ALCAM regulates food allergy by affecting T cell activation.

Relationship between sputum clusterin levels and childhood asthma

BACKGROUND

Clusterin is a sensitive cellular biosensor of oxidative stress and has been studied as a biomarker for inflammation-associated diseases. Clusterin levels in childhood asthma have not been evaluated.

OBJECTIVES

(1) To evaluate sputum clusterin levels in children with asthma compared to a control group. (2) To assess the relationships between sputum clusterin levels and airway inflammation, pulmonary function, and bronchial hyperresponsiveness.

METHODS

This study included 170 children aged 5-18 years with stable asthma (n = 91), asthma exacerbation (n = 29), or no asthma (healthy controls; n = 50). Induced sputum, pulmonary function, and methacholine challenge tests were performed. Stable asthma was classified into two groups according to the severity. Clusterin levels in sputum were measured using an enzyme-linked immunosorbent assay.

RESULTS

Children with stable asthma had a higher clusterin level than healthy controls [4540 (3872-5651) pg/mL vs. 3857 (1054-4369) pg/mL, P < 0.001]. The clusterin level was also more elevated in eosinophil-dominant sputum than in non-eosinophilic sputum in stable asthma [5094 (4243-6257) pg/mL vs. 4110 (1871-4839) pg/mL, P = 0.0017]. Clusterin levels were associated with asthma severity. Paradoxically, clusterin levels were lower during asthma exacerbation than in stable asthma [1838 (350-4790] pg/mL vs. 4540 (3872-5651) pg/mL, P < 0.001]. Clusterin levels were strongly correlated with the methacholine concentration that caused a 20% decrease in the forced expiratory volume in 1 s (r = -0.617, P < 0.001); there was no significant correlation between clusterin levels and other pulmonary function parameters.

CONCLUSIONS AND CLINICAL RELEVANCE

Clusterin levels were altered in children with stable asthma and asthma exacerbation because of its antioxidant and anti-inflammatory effects. Clusterin may be a marker that reflects airway inflammation and severity of symptoms, and it can be used in the assessment and management of childhood asthma.

Recombinant factor IX (BAX326) in previously treated paediatric patients with haemophilia B: a prospective clinical trial

A newly developed recombinant factor IX (BAX326(1) ) was investigated for prophylactic use in paediatric patients aged <12 years with severe (FIX level <1%) or moderately severe (FIX level 1-2%) haemophilia B. The aim of this prospective clinical trial was to assess the safety, haemostatic efficacy and pharmacokinetic profile of BAX326 in previously treated paediatric patients. BAX326 was administered as prophylaxis twice a week for a period of 6 months, and on demand for treatment of bleeds. Safety was assessed by the occurrence of related AEs, thrombotic events and immunologic assessments. Efficacy was evaluated by annualized bleeding rate (ABR), and by treatment response rating (excellent, good, fair, none). PK was assessed over 72 h. None of the 23 treated paediatric subjects had treatment-related SAEs or AEs. There were no thrombotic events, inhibitory or specific binding antibodies against FIX, rFurin or CHO protein. Twenty-six bleeds (19 non-joint vs. 7 joint bleeds) occurred (mean ABR 2.7 ± 3.14, median 2.0), of which 23 were injury-related. Twenty subjects (87%) did not experience any bleeds of spontaneous aetiology. Haemostatic efficacy of BAX326 was excellent or good for >96% of bleeds (100% of minor, 88.9% of moderate and 100% of major bleeds); the majority (88.5%) resolved after 1-2 infusions. Longer T1/2 and lower IR were observed in younger children (<6 years) compared to those aged 6 to 12 years. BAX326 administered as prophylactic treatment as well as for controlling bleeds is efficacious and safe in paediatric patients aged <12 years with haemophilia B.

Clinical Impact of Non-High Density Lipoprotein-Cholesterol and Apolipoprotein B on Clinical Outcomes in Metabolic Syndrome Patients With Acute Myocardial Infarction Undergoing Percutaneous Coronary Intervention

Background and Objectives

Subjects and Methods

Results

Conclusion

Basic rules of parenteral fluid therapy

The following basic rules of parenteral fluid therapy are formulated with the aim of alleviating concern and confusion about i.v. fluid orders that are experienced by most physicians: Don't be generous with fluid; in determining the water intake, one must know the usual water output through the kidney, skin and lung; one must know the quantities of the electrolytes and nutrients that are being given, and know the initial volume of distribution (usually the ECF); one must know the aim of fluid therapy; one must not give and remove the same substance at the same time; one must be aware that hypertonic saline contains less water for a given amount of Na than isotonic saline; one must be familiar with different i.v. solutions and i.v. additives; one must be aware that the kidney does not manufacture water or electrolytes except for bicarbonate; for short-term fluid therapy, divalent ions (Ca, Mg, and P) do not need replacement; one should think about COP-wedge gradient in determining the type of fluid to be given.

Integrative physiology of basal water permeability in the distal nephron: implications for the syndrome of inappropriate secretion of antidiuretic hormone

Patients who drink more electrolyte-free water than they can excrete may develop hyponatremia. A subgroup of hyponatremic patients has a reduced excretion of electrolyte-free water and a low rate of excretion of solutes even though vasopressin is not detected in their plasma. Basal water permeability in the distal nephron, by permitting a limited volume of electrolyte-free water to be reabsorbed, offers a way to help explain these findings. Basal water permeability will also be considered from the perspective of integrative physiology in evolutionary and developmental biology settings. Its possible clinical importance will be explored in patients with chronic hyponatremia who have a low distal volume delivery. These patients may develop osmotic demyelination if a large solute load leads to a very rapid excretion of electrolyte-free water.

Purification and structural analysis of the hepatitis B virus preS1 expressed from Escherichia coli

The preS1 of hepatitis B virus (HBV) is located at the outermost part of the envelope protein and possesses several functionally important regions such as hepatocyte receptor-binding site and virus-neutralizing epitopes. As the first step to understand the structure-function relationship for the preS1 antigen, we have purified the preS1 and performed its structural characterization by circular dichroism (CD) spectroscopy. The preS1 was purified to near homogeneity from bacterially expressed glutathione S-transferase (GST)-preS1 fusion protein by two-step purification, affinity chromatography on glutathione-agarose column, and cation-exchange chromatography on Mono S column. The CD analysis showed that the purified preS1, which was largely unstructured in aqueous solution, acquired a significant (16%) alpha-helical structure when analyzed in 50% trifluoroethanol or 20 mM SDS. The results suggest that the preS1 assumes a mainly unstructured conformation and may form induced secondary structures upon binding to target proteins or under hydrophobic environment.

New xenicane diterpenoids from the gorgonian Acalycigorgia inermis

Eight diterpenes and norditerpenes including five new xenicane metabolites (4--8) have been isolated from the gorgonian Acalycigorgia inermis. The structures of these compounds have been determined by combined spectroscopic analysis. The new compounds exhibited significant cytotoxicity against a human leukemia cell-line.

Correlation between radiology resident rotation performance and examination scores

RATIONALE AND OBJECTIVES

The authors' purpose was to determine whether there is a relationship between subjective assessment of radiology resident performance on individual rotations and objective assessment of radiology resident performance on the American College of Radiology (ACR) in-training and American Board of Radiology (ABR) written examinations.

MATERIALS AND METHODS

Records of 81 radiology residents completing their residency between 1991 and 2000 were reviewed. Mean scores from all rotation evaluation forms obtained during the study period were calculated for each residency year. The means of the overall raw scores and percentiles obtained on the annual ACR in-training examinations during the first 3 years of residency and of the written portion of the ABR examination taken during the 4th year of residency were also determined. Rotation evaluation scores were then compared to examination scores obtained during the same year of residency, and correlation coefficients were obtained.

RESULTS

In the 2nd, 3rd, and 4th years of radiology residency, there is positive correlation between rotation evaluation scores and overall scores from the corresponding ACR in-training examination and written portion of the ABR examination taken during the same year. In contrast, in the 1st year of residency, resident rotation evaluation scores do not correlate with ACR in-training examination scores.

CONCLUSION

Residents who are perceived as doing well on their rotations after the 1st year of residency are more likely to do well on standardized written examinations.

How well does applicant rank order predict subsequent performance during radiology residency?

RATIONALE AND OBJECTIVES

Residency selection committees expend substantial time and resources on assessing the quality of residency applicants to derive an appropriate rank order for the National Residency Matching Program. The authors determined whether there is a relationship between the rank number or rank percentile of applicants selected for a residency training program and subsequent radiology residency performance.

MATERIALS AND METHODS

Records of radiology residents completing their residency between 1991 and 1998 were reviewed. Available rank numbers and rank percentiles for each resident were compared with subsequent performance, as assessed subjectively by 4th-year radiology rotation evaluation forms and retrospective recall of four senior faculty members and objectively by numerical and percentile scores on the written portion of the American Board of Radiology (ABR) examinations. Correlation coefficients were obtained for each comparison.

RESULTS

Rank number and rank percentile were not significantly correlated with 4th-year resident rotation evaluations or ABR written examination scores or percentiles. A small correlation existed between rank order and retrospective evaluation of resident performance by the four senior faculty.

CONCLUSION

Applicant rank number and rank percentile do not correlate with subsequent radiology residency performance as assessed on rotation evaluation forms or the ABR written examinations.

New perspectives on acid-base balance

This review will cover two main areas of acid-base balance, both of which are attended with much misconception and misunderstanding. One is the external balance of acids and alkali; the other is the contribution of bone buffering in acute and chronic metabolic acidosis.

The importance of race in medical student performance of an AIDS risk assessment interview with simulated patients

INTRODUCTION

This study was done to ascertain the effect of race on medical student-patient communication. The primary hypothesis was that interviewing performance scores would be higher when race of student and race of simulated patient instructor (SPI) were concordant than when they were discordant.

METHODS

Data obtained from student interactions with four Caucasian and four African American female SPIs participating in a case involving an AIDS risk assessment interview were analysed. Performance was assessed using two instruments: an 8-item behaviourally anchored interviewing skills scale and a 14-item checklist reflecting content relevant to sexual behaviour and AIDS risk. SPI groups were comparable and SPIs were trained to a high level of inter-rater reliability. Students (24 African American and 180 non-African American) were assigned to SPIs based on the spelling of the student's name. Performance was scored independently at the conclusion of each interview by both the SPI and the student her/himself.

RESULTS

African American students had lower scale scores than non-African American students in interactions with Caucasian (but not African American) SPIs; and all student scores, both on the skills scale and the content checklist, were higher with African American than with Caucasian SPIs (as assessed by both SPI and student). Women students had higher scores than men.

CONCLUSIONS

Race of SPI has an influence on student performance of an AIDS risk assessment interview. Further studies focusing on racial interactions in the medical interview are required. It appears that race of SPI may need to be accounted for in the development and interpretation of SPI-based clinical competence exams.

Isolation and characterization of polymorphic cDNAs partially encoding ADP-glucose pyrophosphorylase (AGPase) large subunit from sweet potato

cDNA clones encoding sweet potato AGPase large subunit (iAGPLI) from the cDNA library constructed from the tuberous root were isolated. Two clones were characterized and named iAGPLI-a and iAGPLI-b. They were 1,661 bp and 1,277 bp in length and contained partial open reading frames of 450 and 306 amino acids, respectively. Both nucleic acid and amino acid sequence identities between iAGPLI-a and iAGPLI-b were 83.8% and 97.3%, respectively. Based on the amino acid sequence analysis, iAGPLI-a and iAGPLI-b share the highest sequence identity (81%) with potato AGPase large subunit. The iAGPLI-a and iAGPLI-b genes were expressed predominantly in the stem and weakly in the tuberous root, and no transcript was expressed in other tissues. The sweet potato genome contains several copies of the iAGPLI gene.

Light chain of natural antibody plays a dominant role in protein antigen binding

Examinations of the contribution and the specificity of heavy (H) and light (L) chains of natural antibodies to antigen binding may help us to better understand antigen recognition and the development of naive B cells. We previously generated natural Fab antibody fragments reactive to preS1 of HBV using a naive, non-immunized Fab antibody library derived from peripheral B cells of a normal healthy volunteer. We now constructed expression vectors for the Fd (VH + CH1), L chain, and scFv fragments using the sequences encoding parental Fabs as a source of natural antibody genes. The recombinant antibody fragments were expressed as inclusion bodies in E. coli BL21 (DE) cells. When denatured and then refolded, the antibody fragments retained their binding properties. Recombinant L chains and scFvs exhibited three- to 40-fold higher affinities (in the order of 10(7) M(-1)) over the parental Fabs, whereas the affinities of Fds (in the order of 10(5) M(-1)) were much lower compared to the parental Fabs. The results obtained from sandwich ELISA revealed that the L chains bound the virus more efficiently than Fds. Additional experiments were performed to evaluate the specificity of the recombinant fragments for surface proteins of HBV. Fds and L chains were reactive towards HBsAg and the preS2 peptide as well as preS1 and showed patterns of epitope recognition quite different from those of parental Fabs. The data presented here demonstrate that the prominence of the L chain in determining protein binding activity is a property of natural antibodies and is quite unlike the antibodies induced by immunization, and that the specificity of Fab is not determined by the individual antibody chain but by the correct pairing of H and L chain.

Cerebral salt-wasting syndrome. We need better proof of its existence

It is widely believed that the cerebral salt-wasting syndrome (CSWS) exists as an entity distinct from the syndrome of inappropriate ADH secretion, and that it is characterized by evidence of severe renal salt wasting that results in volume depletion and hyponatremia. Proof of the existence of CSWS as an entity requires documentation of renal salt wasting and volume depletion. The present review has been undertaken to examine the evidence that the CSWS is a separate entity. In this effort, we have discussed various methods of documentation of volume depletion, and then reviewed reported cases of CSWS to determine whether volume depletion and renal salt wasting have been clearly demonstrated. Our review has led us to conclude that not one case of purported CSWS has demonstrated clear evidence of volume depletion and renal salt wasting. If renal salt wasting had been proven in these cases, we would conclude that the likely site of renal salt transport was the proximal tubule. The proximal site of salt transport defect has been suggested by the absence of hyperreninemia and hypokalemia, which would be a distinguishing feature of Bartter's syndrome and Gitelman's syndrome.

Characteristics of the intracavity dispersion in an erbium-doped fiber laser

We have found theoretically that the intracavity dispersion of a laser is independent of the pumping power and wavelength and that the resonant group-velocity dispersion vanishes. We have experimentally observed that the intracavity dispersion of an erbium-doped fiber laser was independent of the pumping power and wavelength within the measuring error, which agrees well with our theoretical predictions.

Acute hyponatremia in the perioperative period: insights into its pathophysiology and recommendations for management

Our purpose is to review the topic of acute postoperative hyponatremia by focusing on pertinent aspects of the physiology of water and solute excretion. Four areas will be highlighted: an examination of the source of addition of electrolyte-free water, an exploration of the basis for the very large natriuresis that occurs during cerebral salt wasting following neurosurgery, possible reasons to explain why acute postoperative hyponatremia may pose a greater risk for young women [Ayus and Arieff 1996, Ayus et al. 1992, Arieff 1986, Wijdick et al. 1991], and issues related to treatment of acute hyponatremia.

D-lactic acidosis. A review of clinical presentation, biochemical features, and pathophysiologic mechanisms

This report describes a case of d-lactic acidosis observed by the authors and then reviews all case reports of d-lactic acidosis in the literature in order to define its clinical and biochemical features and pathogenetic mechanisms. The report also reviews the literature on metabolism of d-lactic acid in humans. The clinical presentation of d-lactic acidosis is characterized by episodes of encephalopathy and metabolic acidosis. The diagnosis should be considered in a patient who presents with metabolic acidosis and high serum anion gap, normal lactate level, negative Acetest, short bowel syndrome or other forms of malabsorption, and characteristic neurologic findings. Development of the syndrome requires the following conditions 1) carbohydrate malabsorption with increased delivery of nutrients to the colon, 2) colonic bacterial flora of a type that produces d-lactic acid, 3) ingestion of large amounts of carbohydrate, 4) diminished colonic motility, allowing time for nutrients in the colon to undergo bacterial fermentation, and 5) impaired d-lactate metabolism. In contrast to the initial assumption that d-lactic acid is not metabolized by humans, analysis of published data shows a substantial rate of metabolism of d-lactate by normal humans. Estimates based on these data suggest that impaired metabolism of d-lactate is almost a prerequisite for the development of the syndrome.

Acid production in chronic hemodialysis patients

This study examines endogenous acid production in a group of stable chronic hemodialysis patients with no residual renal function who were admitted to the chronic hemodialysis unit of Mount Sinai Hospital. Net acid production was estimated by the change in body bicarbonate content, which occurs in the interdialytic period. The body bicarbonate content at any time was measured by multiplying the concentration of blood bicarbonate by the apparent bicarbonate space at that time. The apparent bicarbonate space was determined by the change in blood bicarbonate concentration induced by the intravenous administration of a known amount of sodium bicarbonate. Daily sulfuric acid production was also estimated from the reduction in body sulfate content during dialysis. The interdialytic net acid production was measured at approximately 28 mEq/d, a value much lower than that predicted from the protein catabolic rate. This reduced acid production can be explained by reduced sulfuric acid and organic acid production. The mechanism of reduced sulfuric acid production is unknown. Reduced organic acid production is explained partly by the absence of renal excretion of metabolizable organic anions, leaving only the nonmetabolizable fraction as the main source of acid in the interdialytic period.

Teaching smoking-cessation counseling to medical students using simulated patients

OBJECTIVE

Our objective was to evaluate the effectiveness of using simulated patient instructors and the Ockene method to instruct third-year medical students in smoking-cessation counseling techniques.

DESIGN

We used a clinical exercise with self-study preparation and simulated patient instructors.

METHODS

One hundred fifty-nine students participated in a smoking-cessation counseling session in which cognitive and behavioral endpoints were assessed by simulated patient instructors and the students themselves.

RESULTS

Student performance in the cognitive and behavioral components of model smoking-cessation counseling was acceptable. Specific areas of weakness, such as the tendency of students to underemphasize the personal and social benefits of smoking cessation, and to overestimate their competence on a number of skill items, were identified. Student evaluation of the exercise was positive.

CONCLUSIONS

Smoking-cessation counseling can be taught effectively to third-year medical students by simulated patient instructors during a clinical clerkship.

Roles of transmembrane prolines and proline-induced kinks of the lutropin/choriogonadotropin receptor

The lutropin/choriogonadotropin receptor is a seven-helix transmembrane (TM) receptor. A unique feature of TM helices is the content of Pro, which generally is absent in alpha helices of globular proteins. Because Pro disrupts helices and introduces a approximately 26 degrees kink, it has been speculated that Pro plays a crucial role in the structure of TM helices, exoloops, and cytoloops of TM receptors. To examine the roles of the five TM Pros of the lutropin/choriogonadotropin receptor, these residues were individually substituted. Mutant receptors were examined for surface expression, hormone binding, and cAMP induction. Surface expression was monitored after introducing the flag epitope into the receptors. Flag epitopes slightly affected cAMP induction but not hormone binding or surface expression of receptors as monitored by immunofluorescence microscopy and 125I-anti-flag antibody. The results indicate that Pro479 in TM 4 and Pro598 in TM 7 play important yet contrasting roles. Pro479 is crucial for hormone binding at the cell surface but not after solubilization of the receptor. This is more likely due to the Pro side chain than the Pro-induced kink. Pro598 is important for surface expression. The kinks of Pro463 of TM 4, Pro562 of TM 6, or Pro591 of TM 7 are not important because the substitution of Phe for these residues did not significantly impact surface expression, hormone binding, and cAMP induction.

The effect of pass/fail grading and weekly quizzes on first-year students' performances and satisfaction

BACKGROUND

In 1992-93 the University of Michigan Medical School revised its first-year curriculum. An evaluation system using honors, high-pass, pass, and fail grading and only two examinations (a midterm and a final) was replaced with a system using pass/fail grading and weekly quizzes in addition to the two examinations. The objective was to increase students' satisfaction while maintaining a high level of achievement.

METHOD

Students' performance scores and survey data from the final year of the former system (1991-92, 222 students) and the first year of the new system (1992-93, 195 students) were used to investigate whether overall performance decreased and whether the students liked the new approach to grading. Statistical methods used were one-sample t-tests, Student's t-test, and Fisher's Z-test.

RESULTS

Under the new system, the average scores for courses remained well above passing, and no evidence was found that the students achieved at lower levels than had their predecessors with the former, more traditional grading system. Also, higher cumulative pre-final scores (i.e., scores on the weekly quizzes as well as the midterm) did not predict lower, "just passing" achievement on final examinations. The students' responses to the surveys included comments that pass/fail grading eased anxiety and reduced competition while encouraging the students' co-operation.

CONCLUSION

Despite concerns that implementing pass/fail grading for all first-year courses would result in lower overall performance and decreased motivation among students, during the first year of implementation these fears proved to be unfounded as the students continued to perform well and reported greater satisfaction with the new system.

A re-evaluation of the urinary parameters of acid production and excretion in patients with chronic renal acidosis

We have studied acid-base balance in 32 patients attending the renal clinic of Mount Sinai Hospital. The parameters of acid-base balance measured included acid production measured as urinary sulfate and organic anions, net acid excretion measured as urinary ammonia plus titratable acid minus bicarbonate, and net GI absorption of alkali measured by a new method utilizing urinary electrolytes. Net GI absorption of alkali by urinary electrolytes measures alkali addition to the body from the GI tract as well as from any other sources, including bone. All patients had a creatinine clearance less than 80 ml/min and they were divided into two groups: those with normal serum bicarbonate (Group 1; N = 12) and those with subnormal serum bicarbonate (Group 2; N = 20). Hydrogen ion balance was -0.6 +/- 9 mEq/day in the first group, while those in the second group had a hydrogen ion balance of +16 +/- 5 mEq/day. A group of 8 normal controls had a hydrogen ion balance of -0.3 +/- 5 mEq/day. When the sum of all cations was compared with the sum of all anions in the urine, a cation gap of exactly the same magnitude as the positive hydrogen ion balance was found in patients with low serum bicarbonate. In conclusion, our data show that patients with decreased GFR and low serum bicarbonate appear to have a significantly positive hydrogen ion balance. However, we believe that the positive hydrogen ion balance is only apparent, but not real for the following reasons.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycosylation, dimerization, and heparin affinity of lipoprotein lipase in 3T3-L1 adipocytes

The relationship between glycosylation, dimerization, and heparin affinity of lipoprotein lipase (LPL) was studied in 3T3-L1 adipocytes. Three forms of LPL subunits were found in normal cells; totally endo H-resistant (57 kDa), partially sensitive (54 kDa), and totally sensitive (51 kDa) forms. LPL in normal cells was active, dimeric, and showed high affinity for heparin. LPL in cells treated with tunicamycin, preventing the transfer of N-linked oligosaccharide chain, was unglycosylated (51 kDa) and inactive. LPL proteins were found as an aggregate, and had low affinity for heparin. After treatment with castanospermine, an inhibitor of ER glucosidase I, 80% of LPL activity was inhibited. Most of LPL proteins were totally endo H-sensitive, present as an aggregate, and had low affinity for heparin. LPL in cells treated with deoxymannojirimycin, an inhibitor of Golgi mannosidase I, was active, dimeric, and had high affinity for heparin as in normal cells. But LPL subunits were all endo H-sensitive. These results suggest that core glycosylation and subsequent removal of glucose residue is required, but processing after Golgi mannosidase I is not necessary for dimerization and acquisition of high heparin affinity of LPL.

Acid-base balance in chronic peritoneal dialysis patients

Endogenous acid production has never been measured directly in dialysis patients and an empiric formula is used to estimate acid production from their protein catabolic rate. We have studied acid-base balance in 19 stable CAPD patients attending the peritoneal dialysis clinic of Mount Sinai Hospital. They obtained a 24 hour collection of peritoneal dialysis fluid and urine while consuming their usual diet and performing their usual activities. Total alkali gain was calculated from net GI alkali absorption plus urinary net acid excretion plus alkali gain from dialysate, while total acid production was measured directly from the urinary and dialysate excretions of sulfate and organic anions. Net GI alkali absorption was estimated from the difference between cations (Na + K+Ca + Mg) and anions (Cl + 1.8P) in the 24 hour dialysate and urine collections minus the daily total amount of lactate infused. All of our patients had a normal or high serum bicarbonate concentration, which was stable with time. Total alkali gain was virtually identical to total acid production (54.2 vs. 52.4 mEq/day) which suggests that these patients were in neutral acid-base balance. Net GI alkali absorption (22.7 mEq/day) was one of the same range as that of chronic renal failure patients not on dialysis and represented almost one half of the total daily alkali gain. The daily acid production of 52.4 mEq/day was numerically equal to 84% of the protein catabolic rate expressed as g/day, which is similar to the predicted value of 77% of PCR reported in the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of a highly focused case on the effect of small-group facilitators' content expertise on students' learning and satisfaction

BACKGROUND

There has been considerable debate over the need for content expertise to lead a successful small-group discussion for medical students. Some authors feel process expertise related to the conduct of a small group is of more value than content expertise related to the case. At least one study has presented data that suggest content expertise can lead to teacher domination of the learning environment. In an earlier study, the present authors found that students learned more and were more satisfied with small-group instruction when the instruction was facilitated by a faculty member who was an expert in the content of the case. That study also identified no tendency for content experts to dominate the sessions (e.g., through lecturing or otherwise controlling the learning environment). The purpose of the present study was to explore the efficacy of a carefully designed and highly focused case problem to remove the influence of group facilitators' content expertise on students' learning outcomes.

METHOD

The 211 students in the University of Michigan Medical School class of 1994 were randomly assigned to 28 groups in a microbiology and immunology course in the fall of 1991; each small group was led by a faculty facilitator. Complete data were available from 27 groups: 13 groups led by experts and 14 groups led by non-experts. Data collection included observers' codings of interactions between the students and the facilitators (interactional analysis), test scores, and students' ratings of the experience.

RESULTS

Unlike in the previous study, group leaders who were content experts devoted significantly more time to teacher-directed activities than did non-content-expert leaders. However, overall, 62% of the time was devoted to student-initiated activity. The results of the multiple-choice tests that were related specifically to the goals of the case indicated there was no significant difference between the students' performances in the groups led by experts and those led by non-experts. With respect to students' satisfaction, all students gave consistently high ratings to the experience and there was no difference between groups led by expert and non-expert facilitators.

CONCLUSION

The data from this study suggest that a facilitator's content expertise alone does not determine the amount of teacher-directed behavior in a group, the amount of students' learning, or students' satisfaction. The focus built into the case and the amount of facilitator's training directly related to the content of the case are also significant variables related to students' learning, teacher's behavior, and students' satisfaction.

Adapting a diabetes patient education program for use as a university course

A study was conducted to determine if a patient education program, "Life With Diabetes," could be converted to an undergraduate course. The course consisted of seven 2-hour sessions with presentations by a physician, dietitian, psychologist, and clinical nurse specialists. Topics included definition, treatment, nutrition, monitoring, children, older adults, and patient empowerment. A total of 52 students (45 without diabetes, 7 with diabetes) have completed this one-credit course. A patient diabetes knowledge test and a 50-item Diabetes Attitude Survey were administered before and after the course. For the students without diabetes, mean knowledge posttest scores improved significantly, and significant changes were seen on the attitude subscales, with posttest scores moving closer to those of a national panel of diabetes experts. Students with diabetes scored closer to the national panel on the pretest and improved significantly only on the patient autonomy subscale. This course measurably improved knowledge and attitudes among undergraduates, suggesting that a patient education program can be adapted successfully to provide additional training opportunities for diabetes education programs.

Renal stone risk factors in patients with type IV renal tubular acidosis

Renal stone formation is uncommon in patients with type IV renal tubular acidosis (RTA). This study was undertaken to explore the urinary biochemical and physicochemical factors in patients with type IV RTA in order to elucidate the mechanisms that protect them from renal stone formation. Twelve subjects with type IV RTA and 12 matched subjects with a similar degree of kidney impairment but without RTA were studied. Both groups of patients had low urinary excretion of calcium, phosphorus, uric acid, and citrate, probably reflective of kidney impairment. Patients with type IV RTA had a significantly lower urinary pH and urinary excretion of calcium than their matched controls. Hypocitraturia was present in both groups without any significant difference between them. This study suggests that the major protection from renal stone formation in type IV RTA results from impaired renal function and ensuing reduction in renal excretion of stone-forming substances, such as calcium and uric acid.

Alkali absorption and citrate excretion in calcium nephrolithiasis

The role of net gastrointestinal (GI) alkali absorption in the development of hypocitraturia was investigated. The net GI absorption of alkali was estimated from the difference between simple urinary cations (Ca, Mg, Na, and K) and anions (Cl and P). In 131 normal subjects, the 24 h urinary citrate was positively correlated with the net GI absorption of alkali (r = 0.49, p < 0.001). In 11 patients with distal renal tubular acidosis (RTA), urinary citrate excretion was subnormal relative to net GI alkali absorption, with data from most patients residing outside the 95% confidence ellipse described for normal subjects. However, the normal relationship between urinary citrate and net absorbed alkali was maintained in 11 patients with chronic diarrheal syndrome (CDS) and in 124 stone-forming patients devoid of RTA or CDS, half of whom had "idiopathic" hypocitraturia. The 18 stone-forming patients without RTA or CDS received potassium citrate (30-60 mEq/day). Both urinary citrate and net GI alkali absorption increased, yielding a significantly positive correlation (r = 0.62, p < 0.0001), with the slope indistinguishable from that of normal subjects. Thus, urinary citrate was normally dependent on the net GI absorption of alkali. This dependence was less marked in RTA, confirming the renal origin of hypocitraturia. However, the normal dependence was maintained in CDS and in idiopathic hypocitraturia, suggesting that reduced citrate excretion was largely dietary in origin as a result of low net alkali absorption (from a probable relative deficiency of vegetables and fruits or a relative excess of animal proteins).

The relationship between diabetes-related attitudes and patients' self-reported adherence

This study involved 1202 patients who were placed into low adherence or high adherence groups based on their answers to questionnaires. The attitudes of each group were compared for a variety of adherence behaviors. Patients who reported high levels of adherence tended to have attitudes more in accord with diabetes experts. Members of the high adherence group strongly supported the need for special training for health care professionals who treat diabetes, favored team care, accepted the importance of patient compliance, acknowledged the seriousness of non-insulin-dependent diabetes mellitus (NIDDM), and recognized the relationship between glucose control and complications. Differences in attitudes between high- and low adherence groups were more prevalent for difficult adherence areas, eg, diet and exercise, than for easy adherence areas, eg, carrying sweets or diabetic identification. An understanding of patients' attitudes can help diabetes educators and patients develop realistic and relevant self-care plans.

Medical student use of history and physical information in diagnostic reasoning

Clinical data gathering is central to clinical competence. Although research has demonstrated the value to experienced clinicians of information obtained from the history, little is known of how medical students use this information. In the present study, two case simulations (in rheumatoid arthritis and systemic lupus erythematosis) were developed to assess medical student information gathering and utilization. The results indicate that most of the students were already considering the correct diagnosis as a possibility after the presenting complaint and patient description. However, the medical history exerted the strongest influence on transforming the correct diagnosis from just another diagnostic possibility into the favored diagnostic candidate. Students who failed to list the correct diagnosis in the differential diagnosis after obtaining the history were significantly less likely to reach the correct diagnosis at the end of the case. These results confirm the critical importance of the history in medical problem solving.

A comparison of the diabetes-related attitudes of health care professionals and patients

The following study compares the diabetes-related attitudes of sampled health care professionals and patients with diabetes. Attitudes were measured with a revised version of the Diabetes Attitude Scale (DAS) which includes seven factors representing attitudes towards: (1) the need for special training in order to provide diabetes care; (2) patient compliance; (3) the seriousness of noninsulin-dependent diabetes (NIDDM); (4) the relationship between blood glucose levels and the complications of diabetes; (5) the impact of diabetes on the patient's life; (6) patient autonomy; and (7) team care. The highest levels of agreement among patients and professionals concerned the seriousness of NIDDM and the relationship between blood glucose control and the development of the complications of diabetes. The most striking finding of the study was that patients tended to express a significantly more judgmental, moralistic attitude toward patient behavior than did health care professionals.

Renal hypouricemia and absorptive hypercalciuria: a real syndrome

We describe a case of renal hypouricemia due to increased tubular secretion of urate associated with absorptive hypercalciuria. This association has been described in the past, but this is the first time that high plasma levels of 1,25-dihydroxyvitamin D have been reported. A possible cause-and-effect relation between altered uric acid transport and altered vitamin D metabolism in the proximal tubule is suggested.

Effects of expert and non-expert facilitators on the small-group process and on student performance

At the University of Michigan Medical School in 1990, the authors investigated the effects of faculty facilitators' levels of content expertise on the educational process and learning outcomes of small-group teaching sessions. The study was conducted in a microbiology course for second-year students in which four small-group sessions were used to replace 38 hours of lecture and laboratory time. The interactions between 11 expert and ten non-expert faculty facilitators and 156 students were observed and coded. The students' levels of knowledge and satisfaction were measured. The results indicate that, although significant differences in faculty-student interactions were not observed, the students in the 11 groups led by the content experts had higher levels of satisfaction and higher examination scores.

Perceived effectiveness, cost, and availability of patient education methods and materials

To determine the efficacy of and need for patient education methods and media, a needs assessment was sent to 816 members of the American Association of Diabetes Educators. Respondents (n = 325, 40%) included 62% RNs, 36% RDs, 1% other; 62% CDEs. Their mean number of years experience in diabetes education was 8.5, and 99% routinely provided patient education. Respondents indicated that videotapes and slide tapes were the most educationally effective media and books and audiotapes were the least effective. Booklets and videotapes were the most cost-effective and computer-assisted instruction the least effective. While respondents perceived one-to-one counseling, skills training, and diabetes content sessions to be the three most educationally effective methods, support groups and large and small discussion groups were seen as the three most cost-effective educational methods. Among nine potential barriers to quality patient education listed, educators rated lack of third-party reimbursement as a major barrier most frequently and national availability of quality education materials as a barrier least frequently.

Disorders of sodium metabolism: hypernatremia and hyponatremia

OBJECTIVE

Discussion of abnormal plasma sodium concentrations with an emphasis on the pathogenesis, diagnosis, and treatment.

DATA SOURCES

Relevant literature in the English language and the authors' clinical experience.

STUDY SELECTION

No special study has been carried out for the present discussion.

DATA EXTRACTION

The information from the literature and the data from the authors' clinical experience have been used to illustrate important points in the discussion.

DATA SYNTHESIS

A most important aspect in the approach to hypernatremia is determination of the mechanism responsible for impaired water intake. Various mechanisms of abnormal water loss can be determined from measurement of urine osmolality. Hypernatremia is treated by water replacement and measures to reduce abnormal water loss. In most instances, hyponatremia is caused by inappropriate concentration of urine because of either appropriate or inappropriate antidiuretic hormone secretion. The determination of appropriateness of antidiuretic hormone secretion requires the assessment of effective arterial volume. Treatment depends on the pathogenetic mechanism.

CONCLUSIONS

Abnormal plasma sodium concentration results from abnormal water intake or water output. Treatment is guided by determining the pathogenetic mechanism.

Effect of meal on the physiological and physicochemical actions of potassium citrate

The effect of meals on the physiological and physicochemical actions of potassium citrate was examined in 8 patients with nephrolithiasis maintained on a constant metabolic dietary regimen. Potassium citrate (20 mEq. 3 times per day), whether given with food or on an empty stomach, significantly increased urinary pH, citrate and potassium, and decreased urinary calcium and ammonium. Moreover, potassium citrate decreased urinary saturation of calcium oxalate and uric acid, although it slightly increased that of brushite. However, there was no significant difference in these measures when the drug was given with meals from the time when it was given on an empty stomach. Thus, the effect of potassium citrate on urinary risk factors is unaffected by food.