Calcimimetic Use in Dialysis-Dependent Medicare Fee-for-Service Beneficiaries and Implications for Bundled Payment

BACKGROUND

Patients who are dialysis dependent and have secondary hyperparathyroidism (SHPT) may require calcimimetics to reduce parathyroid hormone levels to treatment goals. Medicare currently uses the Transitional Drug Add-on Payment Adjustment (TDAPA) designation under the ESKD Prospective Payment System ("bundled payment") to pay for calcimimetics (the first products eligible for the adjustment); this payment designation for calcimimetics is expected to conclude after 2020. This study explores variability in calcimimetic use across key patient characteristics and its potential effect on policy options for incorporating calcimimetics permanently into the bundle.

METHODS

This descriptive analysis used the 100% sample of Medicare FFS Part B (outpatient) 2018 claims to describe national-, regional-, and patient-level variation (including race, dual eligibility, and dialysis vintage) in calcimimetic use among beneficiaries who are dialysis dependent.

RESULTS

A total of 373,874 beneficiaries were analyzed, 28% had ≥90 days of calcimimetic use during 2018. At the national level, the proportion of patients on dialysis using calcimimetics was roughly 80% higher in Black versus non-Black patients on dialysis, 30% higher in patients on dialysis who were dual eligible versus non-dual eligible, and three times higher in patients with a dialysis vintage ≥3 years versus <3 years (all results unadjusted). Calcimimetic use was similar across census regions, however, substantial variation in calcimimetic use was observed at the facility level. Medicare spending for calcimimetic therapies as a proportion of total Medicare dialysis spending was >10% in approximately 20% of dialysis facilities.

CONCLUSIONS

Although less than a third of beneficiaries use calcimimetics, certain patient-level characteristics are associated with higher rates of maintenance calcimimetic use. Due to the financial pressure many dialysis facilities face, how calcimimetics are incorporated into the bundle may have a direct effect on facility reimbursement for, and patient access to, therapy. Careful consideration will be required to ensure patients who are vulnerable and require treatment for SHPT do not face barriers to appropriate care.

First description of a giant manta ray fetus Mobula birostris (Walbaum 1792) from Tumbes, Peru (Southeast Pacific)

The population of Mobula birostris ("giant manta ray") found in the waters of northern Peru and Ecuador is believed to be the largest in the world (Harding Beirwagen, 2009). This species is considered to be the largest within the group of manta rays, as they attains at least 670 cm disc width (reported to 910 cm) (White et al., 2006) and there is a record of an individual weighing 2000 kg (Kunjipalu Boopendranath, 1981). This species is ovoviviparous (matrotrophic viviparious) (Herbert, 2012). A single pup follows a gestation period of approximently one year, (Marshall et al., 2008, Mendonça et al., 2012). Sucessive pregnancies are speculated to be separated by a refactory period of two or more years (Mendonça et al., 2012). The objective of this study is to record the measurements of a M. birostris fetus of a female caught accidentally in the region of Tumbes, Peru. This is the first record of morphological and morphometric data regarding a manta fetus in Peru.

MDDScore: confirmation of a blood test to aid in the diagnosis of major depressive disorder

BACKGROUND

Previously, a biomarker panel was developed for use as an aid to major depressive disorder (MDD) diagnosis; it consisted of 9 biomarkers associated with the neurotrophic, metabolic, inflammatory, and hypothalamic-pituitary-adrenal axis pathways. This panel and associated algorithm produced good clinical sensitivity and specificity (92% and 81%, respectively) in differentiating MDD patients from individuals without MDD. To further validate the panel, we performed a prospective study using a larger set of new prospectively acquired MDD patients and a similarly collected population of nondepressed subjects. The addition of gender and body mass index (BMI) effects to the algorithm was also evaluated.

METHOD

Blood samples were obtained from MDD patients (n = 68) clinically evaluated at multiple sites in 2011 and 2012 using standard psychiatric assessment tools and structured clinical interviews according to DSM-IV criteria. Blood samples (n = 86) from nondepressed subjects were obtained as controls. MDD and nondepressed samples were randomized into independent training (n = 102) and validation sets (n = 52). Analytes in sera were quantified by immunoassay.

RESULTS

Training set biomarker data were used to develop a logistic regression model that included gender and BMI in a manner that allowed for their interaction with the biochemical analytes. For the training set, the sensitivity and specificity of the test (with 95% CI) were 93% (0.80-0.98) and 95% (0.85-0.99), respectively. This method (designated the MDDScore) was then applied to the independent validation set and had a sensitivity and specificity of 96% (0.77-0.98) and 86% (0.66-0.95), respectively. The overall accuracy for the training set was 94%; the validation set accuracy was 91%.

CONCLUSION

Examination of a randomized independent set of samples confirms the ability of the previously established biomarker panel to identify persons with MDD; the accuracy was over 90%. The improved model that adds gender and BMI to the previously established panel of 9 biomarkers is robust and simple; it provides the most rigorously tested, objective diagnostic test for MDD to date.

Randomised clinical trial: pre-dosing with taribavirin before starting pegylated interferon vs. standard combination regimen in treatment-naïve patients with chronic hepatitis C genotype 1

BACKGROUND

Combination therapy with the ribavirin (RBV) prodrug taribavirin (TBV) and pegylated interferon (PIFN) has produced lower rates of anaemia than with RBV and PIFN. Studies have demonstrated that the sharpest decline in viral load during TBV therapy occurs at Weeks 4 through 6, when TBV reaches steady-state blood levels.

AIM

The current proof-of-concept study was conducted to examine whether first-order viral kinetics could be influenced by pre-dosing TBV to steady state before introducing PIFN.

METHODS

Therapy-naïve patients with chronic hepatitis C virus (HCV) genotype 1 (G1) were randomised to receive (i) TBV 600 mg BID monotherapy for 4 weeks followed by combination therapy with PIFN [pre-dosing arm (n = 23)] or (ii) TBV administered concurrently with PIFN [standard dosing arm (n = 19)].

RESULTS

More patients achieved undetectable virus or a ≥2-log(10) reduction of HCV RNA at Week 4 in the pre-dosing vs. the standard dosing arm [33% vs. 22% (P = 0.497)]. There was also a trend towards greater reduction in mean log(10) change in HCV RNA in the pre-dosing vs. the standard dosing arm, which was statistically significant at Day 1 [-0.34 ± 0.46 vs. 0.09 ± 0.32 (P < 0.003)] but not at other time points up to Week 24. No significant difference was observed in the rates of anaemia (haemoglobin <10 g/dL) between study arms (4.5% vs. 5.3%).

CONCLUSIONS

Pre-dosing TBV prior to starting PIFN produces a trend towards improved efficacy although statistical significance was not reached in this small patient population. These results warrant larger clinical trials of TBV pre-dosing.

The pathophysiology, medical management and dental implications of adult attention-deficit/hyperactivity disorder

BACKGROUND

Few published reports in the dental literature have focused on adult attention-deficit/hyperactivity disorder (ADHD) and its dental implications.

TYPES OF STUDIES REVIEWED

The authors conducted a MEDLINE search for the period 2000 through 2005 using the terms "adult" and "attention-deficit" to define ADHD's pathology, medical treatment and dental implications.

RESULTS

ADHD is a developmental condition that affects slightly more than 4 percent of the adult U.S. population. Its symptoms include inattention, hyperactivity and impulsivity that can cause personal, social, occupational and leisure-time dysfunction. Medications used to treat the disorder include stimulants, selective noradrenergic uptake inhibitors and tricyclic antidepressants.

CLINICAL IMPLICATIONS

The oral health of people with ADHD may be compromised by inattention and impulsivity that impair home care regimens and can lead to cigarette addiction, which may cause oral cancer and damage the periodontium, and excessive ingestion of caffeinated sugar-laden soft drinks that promote dental caries. To safely care for this patient population, dentists must be familiar with the stimulant and nonstimulant medications used to treat adult ADHD, because these drugs can cause adverse orofacial and systemic reactions and interact adversely with dental therapeutic agents.

Depot-specific regulation of glucose uptake and insulin sensitivity in HIV-lipodystrophy

Altered fat distribution is associated with insulin resistance in HIV, but little is known about regional glucose metabolism in fat and muscle depots in this patient population. The aim of the present study was to quantify regional fat, muscle, and whole body glucose disposal in HIV-infected men with lipoatrophy. Whole body glucose disposal was determined by hyperinsulinemic clamp technique (80 mU x m(-2) x min(-1)) in 6 HIV-infected men and 5 age/weight-matched healthy volunteers. Regional glucose uptake in muscle and subcutaneous (SAT) and visceral adipose tissue (VAT) was quantified in fasting and insulin-stimulated states using 2-deoxy-[18F]fluoro-D-glucose positron emission tomography. HIV-infected subjects with lipoatrophy had significantly increased glucose uptake into SAT (3.8 +/- 0.4 vs. 2.3 +/- 0.5 micromol x kg tissue(-1) x min(-1), P < 0.05) in the fasted state. Glucose uptake into VAT did not differ between groups. VAT area was inversely related with whole body glucose disposal, insulin sensitivity, and muscle glucose uptake during insulin stimulation. VAT area was highly predictive of whole body glucose disposal (r2 = 0.94, P < 0.0001). This may be mediated by adiponectin, which was significantly associated with VAT area (r = -0.75, P = 0.008), and whole body glucose disposal (r = 0.80, P = 0.003). This is the first study to directly demonstrate increased glucose uptake in subcutaneous fat of lipoatrophic patients, which may partially compensate for loss of SAT. Furthermore, we demonstrate a clear relationship between VAT and glucose metabolism in multiple fat and muscle depots, suggesting the critical importance of this depot in the regulation of glucose and highlighting the significant potential role of adiponectin in this process.

Reducing bioaerosol dispersion from wastewater treatment and its land application: a review and analysis

Wastewater treatment systems and spray irrigation of treated water may spread microorganisms such as bacteria and viruses through dispersion of aerosol particles. A recent review (Brooks, Josephson, Gerba, & Pepper, 2004) identifies appropriate reports. Teltsch and co-authors report findings that suggest effective management controls involve providing buffer zones, irrigating in the daytime and in times of low humidity, reducing microorganism levels in water used for spraying, and testing for multiple types of viruses and bacteria (Teltsch & Katzenelson, 1978; Teltsch, Shuval, & Tadmor, 1980; Teltsch, Kedmi, Bonnet, Borenzstajn-Rotem, & Katzenelson, 1980). Camann, Moore, Harding, and Sorber support these findings. They also note that fecal streptococci are hardier than fecal coliform and appear frequently in background samples, suggesting that this bacterium is a better indicator of background and downwind conditions than are fecal coliform bacteria. In their study, storage prior to spray irrigation reduced microorganism concentrations by 99 percent. Downwind concentrations of sprayed reservoir water were often comparable to background values (Camann, Moore, Harding, & Sorber, 1988). Italian researchers (Brandi, Sisti, & Amagliani, 2000; Carducci, Gemelli, Cantiani, Casini, & Rovini, 1999; Carducci et al., 2000) confirm variable die-away rates of microorganisms, observe a positive association between fecal streptococci and the presence of viruses, and recommend consideration of submerged aeration for sludge digestion at sewage treatment plants. No reports are available that measure dispersion of bioaerosols from wastewater consistently treated to meet contemporary disinfection standards.

Comparison of quality of life, work productivity and medical resource utilization of peginterferon alpha 2a vs the combination of interferon alpha 2b plus ribavirin as initial treatment in patients with chronic hepatitis C

The on-treatment impact of interferon-based therapies on quality of life (QOL), work productivity, and medical resource utilization has not been systematically studied. We evaluated the effects of treatment with peginterferon alpha (pegIFNalpha) 2a monotherapy and the combination of interferon alpha (IFNalpha) 2b plus ribavirin (RBV) on health-related QOL, work productivity and resource utilization. A total of 412 patients with hepatitis C infection were randomized to open-label treatment with either pegIFNalpha 2a (n = 206) or IFNalpha 2b/RBV (n = 206). PegIFNalpha 2a was administered subcutaneously at a dose of 180 microg once weekly for 48 weeks; and IFNalpha 2b/RBV at doses of 3 MU thrice weekly subcutaneously and 1000-1200 mg/day orally. Outcome measures included the SF-36 Health Survey Questionnaire and additional generic and specific scales. During treatment, for all SF-36 summary and Hepatitis Quality of Life Questionnaire (HQLQ)-specific scales, the pegIFNalpha 2a group experienced less impairment than did the IFNalpha 2b/RBV patients. The between-treatment differences were significant for many of the scores particularly in the first 24 weeks of treatment. Across all measures of work functioning and productivity at each visit, patients randomized to pegIFNalpha 2a treatment showed less impairment relative to the group treated with IFNalpha 2b/RBV. Hence treatment with pegIFNalpha 2a relative to IFNalpha 2b/RBV minimizes the adverse impact of therapy on health-related QOL. Patients randomized to pegIFNalpha 2a had improved work productivity, less activity impairment, decreased need for prescription drugs to treat adverse effects, and better adherence to therapy.

Adefovir dipivoxil alone or in combination with lamivudine in patients with lamivudine-resistant chronic hepatitis B

BACKGROUND AND AIMS

Adefovir dipivoxil possesses potent in vitro and in vivo antiviral activity in wild-type hepatitis B. This study assessed the safety and efficacy of adefovir dipivoxil alone and in combination with lamivudine compared with ongoing lamivudine therapy in patients with chronic hepatitis B with compensated liver disease and lamivudine-resistant hepatitis B virus (HBV).

METHODS

Fifty-nine hepatitis B e antigen (HBeAg)-positive patients with genotypic evidence of lamivudine-resistant HBV, serum alanine aminotransferase (ALT) level > or =1.2 times the upper limit of normal, and serum HBV DNA level > or =6 log(10) copies/mL despite ongoing treatment with lamivudine were randomized to adefovir dipivoxil 10 mg, lamivudine 100 mg, or addition of adefovir dipivoxil to ongoing lamivudine daily. The primary end point was the time-weighted average change from baseline in serum HBV DNA level (DAVG) up to week 16.

RESULTS

Rapid reductions in serum HBV DNA level were seen by 4 weeks in all recipients of adefovir dipivoxil; DAVG(16) was -0.07 in the lamivudine group compared with -2.45 and -2.46 log(10) copies/mL in the adefovir dipivoxil/lamivudine and adefovir dipivoxil monotherapy groups, respectively (P < 0.001). Median change from baseline in serum HBV DNA level at week 48 was 0.0, -3.59, and -4.04 log(10) copies/mL in the lamivudine, adefovir dipivoxil/lamivudine, and adefovir dipivoxil groups, respectively. ALT level normalized in 10 of 19 (53%) and 9 of 18 (47%) recipients of adefovir dipivoxil/lamivudine and adefovir dipivoxil, respectively, compared with 1 of 19 (5%) recipients of lamivudine. Three patients receiving adefovir dipivoxil or adefovir dipivoxil/lamivudine and none receiving lamivudine monotherapy were HBeAg negative at week 48 and one became hepatitis B surface antigen negative.

CONCLUSIONS

These data, limited to patients with compensated liver disease, indicate that adefovir dipivoxil alone or in combination with ongoing lamivudine therapy provides effective antiviral therapy in patients with lamivudine-resistant HBV.

Cytomegalovirus in hematopoietic stem cell transplant recipients: current status, known challenges, and future strategies

Cytomegalovirus (CMV) infection is a major cause of morbidity and mortality after hematopoietic stem cell transplantation. Significant progress has been made in the prevention of CMV disease over the past decade, but prevention of late CMV disease continues to be a challenge in selected high-risk populations. The pretransplantation CMV serostatus of the donor and/or recipient remains an important risk factor for posttransplantation outcome despite the use of antiviral prophylaxis and preemptive therapy; CMV-seropositive recipients of T cell-depleted grafts in particular continue to have a survival disadvantage compared with seronegative recipients with seronegative donors. The risk of developing antiviral drug resistance remains low in most patients; however, in a setting of intense immunosuppression (eg, after transplantation from a haploidentical donor), the incidence may be as high as 8%. Primary CMV infection via blood transfusion can be reduced by the provision of seronegative or leukocyte-depleted blood products; however, a small risk of 1% to 2% of CMV disease remains. Surveillance and preemptive therapy are effective in preventing the sequelae of transfusion-related CMV infection. Indirect immunomodulatory effects of CMV are increasingly recognized in hematopoietic stem cell transplant recipients. Strategies currently being investigated include long-term suppression of CMV with valganciclovir for the prevention of late CMV infection and disease, adoptive transfer of CMV-specific T cells, and donor and recipient vaccination strategies.

Long-term improvement in functional dyspepsia using hypnotherapy

BACKGROUND & AIMS

We have shown hypnotherapy (HT) to be effective in irritable bowel syndrome, with long-term improvements in symptomatology and quality of life (QOL). This study aimed to assess the efficacy of HT in functional dyspepsia (FD).

METHODS

A total of 126 FD patients were randomized to HT, supportive therapy plus placebo medication, or medical treatment for 16 weeks. Percentage change in symptomatology from baseline was assessed after the 16-week treatment phase (short-term) and after 56 weeks (long-term) with 26 HT, 24 supportive therapy, and 29 medical treatment patients completing all phases of the study. QOL was measured as a secondary outcome.

RESULTS

Short-term symptom scores improved more in the HT group (median, 59%) than in the supportive (41%; P = 0.01) or medical treatment (33%; P = 0.057) groups. HT also benefited QOL (42%) compared with either supportive therapy (10% [P < 0.001]) or medical treatment (11% [P < 0.001]). Long-term, HT significantly improved symptoms (73%) compared with supportive therapy (34% [P < 0.02]) or medical treatment (43% [P < 0.01]). QOL improved significantly more with HT (44%) than with medical treatment (20% [P < 0.001]). QOL did improve in the supportive therapy (43%) group, but 5 of these patients commenced taking antidepressants during follow-up. A total of 90% of the patients in the medical treatment group and 82% of the patients in the supportive therapy group commenced medication during follow-up, whereas none in the HT group did so (P < 0.001). Those in the HT group visited their general practitioner or gastroenterologist significantly less (median, 1) than did those in the supportive therapy (median, 4) and medical treatment (median, 4) groups during follow-up (P < 0.001).

CONCLUSIONS

HT is highly effective in the long-term management of FD. Furthermore, the dramatic reduction in medication use and consultation rate provide major economic advantages.

The burden of selected digestive diseases in the United States

BACKGROUND & AIMS

Gastrointestinal (GI) and liver diseases inflict a heavy economic burden. Although the burden is considerable, current and accessible information on the prevalence, morbidity, and cost is sparse. This study was undertaken to estimate the economic burden of GI and liver disease in the United States for use by policy makers, health care providers, and the public.

METHODS

Data were extracted from a number of publicly available and proprietary national databases to determine the prevalence, direct costs, and indirect costs for 17 selected GI and liver diseases. Indirect cost calculations were purposefully very conservative. These costs were compared with National Institutes of Health (NIH) research expenditures for selected GI and liver diseases.

RESULTS

The most prevalent diseases were non-food-borne gastroenteritis (135 million cases/year), food-borne illness (76 million), gastroesophageal reflux disease (GERD; 19 million), and irritable bowel syndrome (IBS; 15 million). The disease with the highest annual direct costs in the United States was GERD ($9.3 billion), followed by gallbladder disease ($5.8 billion), colorectal cancer ($4.8 billion), and peptic ulcer disease ($3.1 billion). The estimated direct costs for these 17 diseases in 1998 dollars were $36.0 billion, with estimated indirect costs of $22.8 billion. The estimated direct costs for all digestive diseases were $85.5 billion. Total NIH research expenditures were $676 million in 2000.

CONCLUSIONS

GI and liver diseases exact heavy economic and social costs in the United States. Understanding the prevalence and costs of these diseases is important to help set priorities to reduce the burden of illness.

Gene and antisense delivery in alcoholism research

This article represents the proceedings of a symposium at the 2001 annual meeting of the Research Society on Alcoholism in Montreal, Canada. Drs. Yedy Israel and Fulton Crews were organizers and co-chairpersons. The presentations were (1) Introduction to the symposium, by Yedy Israel; (2) Gene delivery to the brain, by Fulton T. Crews; (3) Gene therapy in alcoholic liver injury, by Ronald Thurman; and (4) Antisense oligonucleotides and antisense-gene delivery, by Yedy Israel.

Sinusoidal spread of liver metastases from renal cell carcinoma: simulation of diffuse liver disease on MR imaging

Rarely, hepatic metastases can simulate hepatic infiltrative diseases. We present a case of a patient with advanced metastatic renal cell carcinoma who developed hepatomegaly and clinical signs of hepatocellular injury. On magnetic resonance imaging, the injury simulated a diffuse process, e.g., acute fulminant viral or chemical hepatitis or drug toxicity. Despite its high resolution, magnetic resonance imaging might not depict focal lesions in patients with extensive metastases. In correlation with clinical history, malignant disease should be considered when diffusely abnormal hepatic signal intensity is noted.

Diffuse desmoplastic breast carcinoma metastases to the liver simulating cirrhosis at MR imaging: report of two cases

Two patients with breast carcinoma, without a prior diagnosis of liver lesions, had proved desmoplastic hepatic metastases that resembled cirrhosis at magnetic resonance (MR) imaging. The cirrhotic appearance of the livers may have resulted from the hepatotoxic effects of chemotherapy and/or hepatic infiltration by the metastatic tumor itself. Despite its high soft-tissue contrast, MR imaging may fail to depict extensive metastases from breast carcinoma, especially when they simulate other diseases (eg, cirrhosis). Correlation of MR imaging findings with clinical history is mandatory.

Inhibition of insulin-like growth factor-I signaling by ethanol in neuronal cells

BACKGROUND

Ethanol inhibits insulin-like growth factor-I receptor (IGF-IR) activation. However, the potency of ethanol for inhibition of the IGF-IR and other receptor tyrosine kinases varies considerably among different cell types. We investigated the effect of ethanol on IGF-I signaling in several neuronal cell types.

METHODS

IGF-I signaling was examined in SH-SY5Y neuroblastoma cells, primary cultured rat cerebellar granule neurons, and rat NG-108 neuroblastoma x glioma hybrids. The tyrosine phosphorylation of IGF-IR, IRS-2, Shc, and p42/p44 MAP kinase (MAPK), and the association of Grb-2 with Shc, were examined by immunoprecipitations and Western blotting.

RESULTS

IGF-I-mediated tyrosine phosphorylation of MAPK was inhibited by ethanol in all cell lines. IGF-IR autophosphorylation was markedly inhibited by ethanol in SH-SY5Y cells, was only mildly inhibited in cerebellar granule neurons, and was unaffected in rat NG-108 cells. In vitro tyrosine autophosphorylation of immunopurified IGF-IR obtained from all cell lines was inhibited by ethanol. There was also differential ethanol sensitivity of IRS-2 and Shc phosphorylation, and the association of Shc with IRS-2, among the different cell types.

CONCLUSIONS

The findings demonstrate that IGF-I-mediated MAPK activation is a sensitive target of ethanol in diverse neuronal cell types. The data are consistent with ethanol-induced inhibition of IGF-IR activity, although the extent of IGF-IR tyrosine autophosphorylation per se is a poor marker of the inhibitory action of ethanol on this receptor. Furthermore, despite uniform inhibition of MAPK in the different neuronal cell types, tyrosine phosphorylation of proximal mediators of the IGF-IR are differentially inhibited by ethanol.

Psychosocial therapies in diabetes: report of the Psychosocial Therapies Working Group

OBJECTIVE

To review key advances in the behavioral science literature related to psychosocial issues and therapies for persons with diabetes, to discuss barriers to research progress, and to make recommendations for future research.

RESEARCH DESIGN AND METHODS

Key findings from the literature on psychosocial research in diabetes are reviewed separately for children and adults. Specific issues covered include psychosocial adjustment and psychiatric disorders, neurocognitive functioning, quality of life, and psychosocial therapies. Barriers that must be addressed to allow research in this area to progress are discussed. Recommendations are then made concerning high-priority areas for advancing research in the field.

CONCLUSIONS

A substantial amount of behavioral science research has demonstrated that psychosocial factors play an integral role in the management of diabetes in both children and adults. Research has also shown the efficacy of a number of psychosocial therapies that can improve regimen adherence, glycemic control, psychosocial functioning, and quality of life. More research in this area is needed to develop psychosocial intervention programs for specific patient populations and to demonstrate the cost-effectiveness of these approaches.

The longitudinal primary care clerkship at Harvard Medical School

The primary care clerkship (PCC) at Harvard Medical School was established in 1997. The goals are to provide students with longitudinal experiences with patients and to include modern themes in the curriculum: managing illness and clinical relationships over time; finding the best available answers to clinical questions; preventing illness and promoting health; dealing with clinical uncertainty; getting the best outcomes with available resources; working in a health care team; and sharing decision making with patients. The PCC, a required course in the clinical years, meets one afternoon a week for nine months. Students spend three afternoons per month in primary care practices, where they see three to five patients per session and follow at least one patient ("longitudinal patient") over time. Classroom sessions, in both large- and small-group formats, promote a common educational philosophy and experience, and reinforce habits of problem-based learning established in the preclinical years. The students rated 74% of their preceptors excellent, especially praising their ability to facilitate and support good interpersonal relationships with patients, their ability to encourage students' independent evaluation of patients (as opposed to shadowing), and their enthusiasm for teaching. Students saw their longitudinal patients a mean of 4.8 times; 83% saw their patients at least three times. The PCC complements the curriculum of block clerkships in hospitals, and because the two are offered concurrently, students are required to come to terms with two substantially different cultures within medicine. Other medical schools are beginning to develop longitudinal clerkships to ensure that students have essential educational experiences that are difficult to achieve in block, hospital-based clerkships.

Tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) by oxidant stress in cerebellar granule neurons: modulation by N-methyl-D-aspartate through calcineurin activity

Insulin receptor-substrate-1 (IRS-1) is a docking protein for several tyrosine kinase receptors. Upon tyrosine phosphorylation, IRS-1 binds to signaling molecules that express Src homology 2 (SH-2) binding domains, including phosphatidylinositol 3-kinase (PI 3-kinase), phosphotyrosine phosphatase SHP-2 (Syp), Nck, Crk and Grb-2. Hydrogen peroxide (H(2)O(2)) induces tyrosine phosphorylation of key signaling mediators presumably by inhibition of tyrosine phosphatases. In many cell types, the activation of extracellular signal-related kinases (e.g. MAPK) and other protein kinases by H(2)O(2) leads to transcriptional activation. In the current study, we examined the effect of H(2)O(2) on IRS-1 tyrosine phosphorylation in primary cultured rat cerebellar granule neurons. H(2)O(2) stimulated the rapid tyrosine phosphorylation of IRS-1 and p42/p44 MAP kinase, and induced its association with PI 3-kinase. H(2)O(2)-induced IRS-1 phosphorylation was rapidly reversible (5 min) whereas MAPK phosphorylation persisted for up to 1 h. NMDA reversed H(2)O(2)-mediated tyrosine phosphorylation of IRS-1 and its association with PI 3-kinase. The dephosphorylation of IRS-1 by NMDA was calcium-dependent and was inhibited by the calcineurin inhibitor cyclosporine. Calmodulin-dependent tyrosine phosphatase activity of calcineurin was observed in vitro using both immunoprecipitated and recombinant tyrosine-phosphorylated IRS-1 as substrates. These data highlight the role of multiple phosphatases in the regulation of IRS-1 tyrosine phosphorylation and identify a novel functional property of calcineurin.

Liver disease and diabetes mellitus

The liver plays an important role in the pathogenesis of NIDDM. More importantly to the clinician is the myriad of situations in which the care of the patient with diabetes is affected by or causes an effect to the liver. Patients with underlying diabetes can present with abnormal liver chemistries, which can represent findings as benign as hepatic steatosis or as severe as cirrhosis of the liver. The medications used to treat diabetes can be potent hepatotoxins. Several primary liver diseases are associated with increased risk of the development of diabetes. Epidemiologically, there seems to be a correlation between diabetes mellitus, the most common endocrinologic disease, and hepatitis C, the leading cause of chronic liver disease in the United States. In the management of end-stage liver disease, both cirrhosis and orthotopic liver transplantation promote glucose intolerance and diabetes in a number of patients through various mechanisms including insulin resistance and impaired insulin secretion. These relationships highlight both the importance of the liver as an endocrine organ and the multisystem aspects of the patient with diabetes mellitus.