Mitochondrial dysfunction, oxidative stress, and neurodegeneration elicited by a bacterial metabolite in a C. elegans Parkinson's model.

Genetic and idiopathic forms of Parkinson's disease (PD) are characterized by loss of dopamine (DA) neurons and typically the formation of protein inclusions containing the alpha-synuclein (α-syn) protein. Environmental contributors to PD remain largely unresolved but toxins, such as paraquat or rotenone, represent well-studied enhancers of susceptibility. Previously, we reported that a bacterial metabolite produced by Streptomyces venezuelae caused age- and dose-dependent DA neurodegeneration in Caenorhabditis elegans and human SH-SY5Y neurons. We hypothesized that this metabolite from a common soil bacterium could enhance neurodegeneration in combination with PD susceptibility gene mutations or toxicants. Here, we report that exposure to the metabolite in C. elegans DA neurons expressing human α-syn or LRRK2 G2019S exacerbates neurodegeneration. Using the PD toxin models 6-hydroxydopamine and rotenone, we demonstrate that exposure to more than one environmental risk factor has an additive effect in eliciting DA neurodegeneration. Evidence suggests that PD-related toxicants cause mitochondrial dysfunction, thus we examined the impact of the metabolite on mitochondrial activity and oxidative stress. An ex vivo assay of C. elegans extracts revealed that this metabolite causes excessive production of reactive oxygen species. Likewise, enhanced expression of a superoxide dismutase reporter was observed in vivo. The anti-oxidant probucol fully rescued metabolite-induced DA neurodegeneration, as well. Interestingly, the stress-responsive FOXO transcription factor DAF-16 was activated following exposure to the metabolite. Through further mechanistic analysis, we discerned the mitochondrial defects associated with metabolite exposure included adenosine triphosphate impairment and upregulation of the mitochondrial unfolded protein response. Metabolite-induced toxicity in DA neurons was rescued by complex I activators. RNA interference (RNAi) knockdown of mitochondrial complex I subunits resulted in rescue of metabolite-induced toxicity in DA neurons. Taken together, our characterization of cellular responses to the S. venezuelae metabolite indicates that this putative environmental trigger of neurotoxicity may cause cell death, in part, through mitochondrial dysfunction and oxidative stress.

Primary nodal neuroendocrine (Merkel cell) tumor in a patient with HIV infection.

Lymphadenopathy in the human immunodeficiency virus (HIV) can be of diverse etiology, ranging from infection to cancer. A neoplasm of epithelial origin manifested as inguinal lymphadenopathy without a primary lesion is rare. We report a case of Merkel cell tumor confined only to a lymph node in a patient with the acquired immunodeficiency syndrome (AIDS). We believe this is the first report of primary nodal Merkel cell tumor in a patient with HIV. Because Merkel cell tumor is a rare skin neoplasm with features suggestive of high malignant potential, it is important to distinguish a primary nodal Merkel cell tumor from malignant metastatic processes on the one hand and relatively benign causes of adenopathy on the other.

MES-1, a protein required for unequal divisions of the germline in early C. elegans embryos, resembles receptor tyrosine kinases and is localized to the boundary between the germline and gut cells.

During Caenorhabditis elegans embryogenesis the primordial germ cell, P(4), is generated via a series of unequal divisions. These divisions produce germline blastomeres (P(1), P(2), P(3), P(4)) that differ from their somatic sisters in their size, fate and cytoplasmic content (e.g. germ granules). mes-1 mutant embryos display the striking phenotype of transformation of P(4) into a muscle precursor, like its somatic sister. A loss of polarity in P(2) and P(3) cell-specific events underlies the Mes-1 phenotype. In mes-1 embryos, P(2) and P(3) undergo symmetric divisions and partition germ granules to both daughters. This paper shows that mes-1 encodes a receptor tyrosine kinase-like protein, though it lacks several residues conserved in all kinases and therefore is predicted not to have kinase activity. Immunolocalization analysis shows that MES-1 is present in four- to 24-cell embryos, where it is localized in a crescent at the junction between the germline cell and its neighboring gut cell. This is the region of P(2) and P(3) to which the spindle and P granules must move to ensure normal division asymmetry and cytoplasmic partitioning. Indeed, during early stages of mitosis in P(2) and P(3), one centrosome is positioned adjacent to the MES-1 crescent. Staining of isolated blastomeres demonstrated that MES-1 was present in the membrane of the germline blastomeres, consistent with a cell-autonomous function. Analysis of MES-1 distribution in various cell-fate and patterning mutants suggests that its localization is not dependent on the correct fate of either the germline or the gut blastomere but is dependent upon correct spatial organization of the embryo. Our results suggest that MES-1 directly positions the developing mitotic spindle and its associated P granules within P(2) and P(3), or provides an orientation signal for P(2)- and P(3)-specific events.

Initial microbiologic studies did not affect outcome in adults hospitalized with community-acquired pneumonia.

Microbiologic studies (MBSs) fail to identify a specific pathogen in more than 50% of patients with community-acquired pneumonia (CAP). The 1993 American Thoracic Society guideline (ATS-GL) for the management of CAP advised selecting initial antibiotic regimens based on severity of illness and comorbidities. Our study evaluated the role of initial MBS in adult patients hospitalized with CAP and treated according to the ATS-GL. In 184 patients hospitalized at our facility for CAP in 1996, and treated according to the ATS-GL, 25 (14%) failed to respond to initial antibiotic regimens. In these nonresponders, there was no difference in mortality between those in whom antibiotics were changed empirically, and those with MBS-guided changes. We conclude that initial MBS may not be warranted in many adult patients admitted for CAP. Exceptions include patients with conditions that predispose to less common, more resistant pathogens.

Computer networking in an ambulatory health care setting.

Computers are a ubiquitous part of the ambulatory health care environment. Although stand-alone computers may be adequate for a small practice, networked computers can create much more powerful and cost-effective computerized systems. Local area networks allow groups of computers to share peripheral devices and computerized information within an office or cluster of offices. Wide area networks allow computers to securely share devices and information across a large geographical area. Either singly or in combination, these networks can be used to create robust systems to help physicians automate their practices and improve their access to important clinical information. In this article, we will examine common network configurations, explain how they function, and provide examples of real-world implementations of networking technology in health care.

Evil is more than banal: situationism and the concept of evil.

Social psychology as a discipline has given relatively little attention to the problem of evil in society, and those discussions in this field that do exist typically regard evil actions as only varieties of aggression without any characteristics that distinguish them from other forms of intentional mistreatment of others. Because of the field's situationistic perspective emphasizing the individual's susceptibility to the power of the immediate situation, social psychoiogists generally view the fairly high levels of obedience to authority displayed in Milgram's (1963, 1974) classic experiment as the paradigmatic example of evil behavior. For them, much evil is, in Arendt's (1963) well-known phrase, only "banal," and Milgram's findings are often viewed as illustrating the "central dynamic" involved in the slaughter of millions of Jews and other "undesirables" in the Holocaust. This article holds that Milgram's (1974) obedience research does not represent significant features of the Holocaust, especially the sadism that occurred not infrequently, and disregards the vital difference between those who initiated the murderous policy and the others who followed their orders. Building on Darley's (1992) earlier conjectures about the features that ordinary people might consider in judging whether any given action is evil, I suggest that many persons have a prototypic conception of evil and speculate about the dimensions that could be involved in this prototype.

Breaking down the barriers. Improving physician buy-in of CPR systems.

The computer-based patient record (CPR) continues to gain recognition and notoriety as its potential benefits are paralleled by its potential problems. The benefits of an effective CPR system include increased efficiency, improved quality and cost savings. But potential problems may actually be decreased efficiency, lowered quality (rarely), and economic losses. Factors that effect these potential CPR outcomes include system quality, system expense and physician buy-in. But even though CPR systems are starting to show improved quality at more reasonable prices, the lack of physician buy-in may stop groups from pursuing CPR systems at this time. They realize that even a perfect CPR system will ultimately fail unless physicians understand the system and use it appropriately.

Macrorestriction analysis of Caenorhabditis elegans genomic DNA.

The usefulness of genomic physical maps is greatly enhanced by linkage of the physical map with the genetic map. We describe a "macrorestriction mapping" procedure for Caenorhabditis elegans that we have applied to this endeavor. High molecular weight, genomic DNA is digested with infrequently cutting restriction enzymes and size-fractionated by pulsed field gel electrophoresis. Southern blots of the gels are probed with clones from the C. elegans physical map. This procedure allows the construction of restriction maps covering several hundred kilobases and the detection of polymorphic restriction fragments using probes that map several hundred kilobases away. We describe several applications of this technique. (1) We determined that the amount of DNA in a previously uncloned region is < 220 kb. (2) We mapped the mes-1 gene to a cosmid, by detecting polymorphic restriction fragments associated with a deletion allele of the gene. The 25-kb deletion was initially detected using as a probe sequences located approximately 400 kb away from the gene. (3) We mapped the molecular endpoint of the deficiency hDf6, and determined that three spontaneously derived duplications in the unc-38-dpy-5 region have very complex molecular structures, containing internal rearrangements and deletions.

Adjuvant systemic therapy for breast cancer. Issues for primary care physicians.

Chemotherapy, hormone therapy, or both are used for adjuvant management in patients with breast cancer. Early systemic therapy can delay and possibly prevent the progression of micrometastatic disease. Positive axillary nodes constitute the major risk factor for later systemic disease, and most oncologists believe that all women with positive nodes should have adjuvant therapy. In patients with negative nodes, tumor size is apparently the most important factor. The prognosis is excellent when the lesion is smaller than 1 cm, and adjuvant therapy can probably be avoided. However, therapy is generally advisable when the tumor is larger than 2 cm. Although intense scheduled follow-up is beneficial for some patients, it is costly and does not always result in a survival advantage. Asymptomatic patients may do well with considerably less routine testing.

Recurrent anaphylaxis due to unrecognized latex hypersensitivity in two healthcare professionals.

BACKGROUND: Anaphylaxis is a potentially fatal immediate-type reaction and intense effort may be required to identify the allergen responsible. In some cases, a "hidden" allergen may be responsible that is not apparent in spite of careful clinical assessment. OBJECTIVES: This report describes the assessment of two cases of anaphylaxis in which a search for an allergen was initially not conclusive and the diagnosis of idiopathic anaphylaxis was considered. METHODS: Two patients were evaluated by various physicians for anaphylaxis with no clear indication of a responsible allergen. Persistence in evaluation led to the identification of the allergen responsible. RESULTS: In two health care workers latex was identified as the "hidden" cause of anaphylaxis. This allergen had not been considered in either case in initial evaluations. Neither patient has had a recurrence of anaphylaxis since latex was identified as the cause of anaphylaxis. CONCLUSIONS: Although latex is widely recognized as a cause of anaphylaxis, it can still be unrecognized in some cases of recurrent anaphylaxis. Latex must be considered as a "hidden" cause of anaphylaxis, particularly in health care workers.

Hemostasis in renal disease: pathophysiology and management.

The hemostatic abnormalities commonly encountered in patients with renal disease can significantly threaten the well-being of the patient and pose difficult management issues for the clinician. In this review, we explore the pathophysiology underlying the bleeding diathesis and hypercoagulability that can occur. Current therapeutic interventions are also discussed.

What do applicants look for when selecting internal medicine residency programs? A comparison of rating scale and open-ended responses.

OBJECTIVE: To develop reliable scale measures of factors most important to applicants when they select internal medicine residencies and to assess their validity by comparing scores from these measures with responses to open-ended questions. DESIGN: All 353 applicants ranked by the University of North Carolina at Chapel Hill (UNC-CH) for the 1988 National Residency Match Program received a questionnaire after submitting their match lists. First, they listed the three most important factors considered in ranking residency programs and starred the single most important factor out of the three. Then, they rated 41 items on a five-point Likert scale ranging from 1 (not important) to 5 (extremely important). SETTING: Categorical internal medicine residency program at an academic medical center. MEASUREMENTS AND MAIN RESULTS: 315 (88%) applicants responded to the survey. Three reliable scales, Interpersonal Issues (7 items, alpha = 0.78), Reputation (5 items, alpha = 0.77), and Work Issues (11 items, alpha = 0.89), were developed using exploratory factor analysis of applicants' responses to the 41 items. Applicants felt interpersonal issues were very important (mean score = 4.2 +/- 0.5), academic reputation was important (3.3 +/- 0.8), and work issues were less important (2.8 +/- 0.7). The differences between these scores were significant (F = 3.76, p < 0.05). The ratings for the top five items not in these scales also indicated that education and location were very important. These results were corroborated by applicants' responses to the open-ended request to list the three most important factors in ranking residencies. CONCLUSION: These findings suggest that work issues are important, but greater emphasis is placed on interpersonal issues, education, location, and a program's reputation when applicants select residency programs. Furthermore, this study provides evidence supporting the reliability and validity of the three scales.

Validity of the in-training examination for predicting American Board of Internal Medicine certifying examination scores.

OBJECTIVE: To determine whether the results of the Internal Medicine In-Training Examination (ITE) can predict subsequent performance on the American Board of Internal Medicine certifying examination (ABIMCE). DESIGN: Retrospective data review. SETTING: A mixture of six community hospital and university-based internal medicine training programs in the Eastern United States. SUBJECTS: 109 residents who first took the ABIMCE in 1988 or 1989, and who had also taken at least one ITE. MEASUREMENTS: Scores for the composite and subspecialty sections of the ITE were compared with those for the ABIMCE. An R2 was obtained to relate the scores on the two examinations. A cutoff score was derived to maximize the ability of the ITE to discriminate between residents who were likely to pass and those who were likely to fail the ABIMCE. MAIN RESULTS: ABIMCE scores were available for 109 residents who had also taken the ITE during PGY-2 (19), PGY-3 (50), or both years (40). Composite scores on the ABIMCE were highly correlated with those on the ITE-PGY-2 (R2 = 0.593) and the ITE-PGY-3 (R2 = 0.677) (p less than 0.0001 for each). Most of the subspecialty sections on the two examinations were significantly correlated, although less strongly (range of R2 = 0.041 to 0.32) than were the composite scores. An empirically derived cutoff score of the 35th percentile on the ITE-PGY-2 had a positive predictive value of 89% (probability of passing ABIMCE) and a negative predictive value of 83% (probability of failing ABIMCE). CONCLUSIONS: Performance on the ITE can accurately predict and is highly correlated with performance on the ABIMCE. ITE results may therefore be useful in counseling residents about their educational needs in preparation for the ABIMCE.

Therapy of pulmonary nocardiosis in immunocompromised mice.

We compared the bactericidal efficacies of various antimicrobial agents and combinations thereof in experimentally induced Nocardia asteroides pneumonia in immunocompromised mice. Cortisone acetate treatment, which produced impaired cell-mediated immune function, was followed by nasal inoculation of 5 x 10(4) CFU of N. asteroides into each mouse. Therapy was begun 24 h after inoculation and continued for the next 96 h. Dosages of antimicrobial agents resulted in concentrations approximating levels in human serum. Animals from each of nine treatment groups were sacrificed every 24 h. The pulmonary tissue obtained was homogenized and quantitatively cultured. Results were calculated to indicate the number of CFU per gram of lung tissue. Amikacin and imipenem were the two most effective single agents studied. Sulfadiazine and ciprofloxacin were ineffective, and ceftriaxone reduced bacterial counts modestly. Combination therapy did not enhance the bactericidal activities of the agents tested. We conclude that amikacin and imipenem, as well as select broad-spectrum cephalosporins, represent therapy superior to the sulfonamides in this experimental model and may represent alternative treatment for patients who cannot tolerate sulfa agents (e.g., human immunodeficiency virus-infected patients) or who fail primary treatment.

Two distinct forms of active transcription factor CREB (cAMP response element binding protein).

Mammalian cells express two distinct forms of transcription factor CREB (cAMP response element binding protein) that are apparently the products of alternative splicing of the CREB gene transcript. The two proteins differ by a 14-amino acid serine-rich insertion present in one of the CREB isoforms. We show that both CREB isoforms are expressed in many cell types and mammalian species. Both encode proteins that bind specifically to a cAMP response element in vitro. As expected for proteins of this class, the CREB proteins bind DNA as dimers. Both proteins impart cAMP-regulated transcriptional activity to a heterologous DNA-binding domain, showing that cAMP directly modulates the transcriptional stimulatory activity of CREB. The presence of multiple CREB isoforms with identical DNA-binding specificities but differences in the presumed regulatory domain raises the possibility that CREB proteins may be able to integrate distinct regulatory signals at the level of gene transcription.

Loop diuretic and anion modification of NEM-induced K transport in human red blood cells.

The thioalkylating agent N-ethylmaleimide (NEM) causes ouabain-insensitive K loss from human red blood cells. This K loss is inhibited when intracellular Cl is replaced by another permeant anion or when loop diuretics are placed in the incubation medium after NEM exposure. In this report, we have tested the possibility that Cl replacement or loop diuretics not only influence the transport of K induced by NEM but also the interaction of NEM with its target sulfhydryl group. This possibility was examined by replacing intracellular Cl or exposing the cells to loop diuretics before NEM exposure, then measuring K loss in a Cl medium free of loop diuretics. We found that such pretreatment with either Cl substitution or loop diuretics stimulated, rather than inhibited, NEM-induced K loss. This enhancement was not additive in that the increase in K loss induced by anion substitution was not increased further when loop diuretics were also present. These data suggest that anion substitution and loop diuretics enhance the interaction of NEM with its cellular target but inhibit the K loss induced by NEM.