Citations

ABSTRACT The initiation of reverse transcription and nucleocapsid assembly in hepatitis B virus (HBV) depends on the specific recognition of an RNA signal (the packaging signal, ε) on the pregenomic RNA (pgRNA) by the viral reverse transcriptase (RT). RT-ε interaction in the duck hepatitis B virus (DHBV) was recently shown to require the molecular chaperone complex, the heat shock protein 90 (Hsp90). However, the requirement for RT-ε interaction in the human HBV has remained unknown due to the inability to obtain a purified RT protein active in specific ε binding. We now report that Hsp90 is also required for HBV RT-ε interaction. Inhibition of Hsp90 led to diminished HBV pgRNA packaging into nucleocapsids in cells, which depends on RT-ε interaction. Furthermore, using truncated HBV RT proteins purified from bacteria and five purified Hsp90 chaperone factors, we have developed an in vitro RT-ε binding assay. Our results demonstrate that Hsp90, in a dynamic process that was dependent on ATP hydrolysis, facilitated RT-ε interaction in HBV, as in DHBV. Specific ε binding required sequences from both the amino-terminal terminal protein and the carboxy-terminal RT domain. Only the cognate HBV ε, but not the DHBV ε, could bind the HBV RT proteins. Furthermore, the internal bulge, but not the apical loop, of ε was required for RT binding. The establishment of a defined in vitro reconstitution system has now paved the way for future biochemical and structural studies to elucidate the mechanisms of RT-ε interaction and chaperone activation.

Background— The primary aim and central hypothesis of the study are that a designated syncope unit in the emergency department improves diagnostic yield and reduces hospital admission for patients with syncope who are at intermediate risk for an adverse cardiovascular outcome. Methods and Results— In this prospective, randomized, single-center study, patients were randomly allocated to 2 treatment arms: syncope unit evaluation and standard care. The 2 groups were compared with χ 2 test for independence of categorical variables. Wilcoxon rank sum test was used for continuous variables. Survival was estimated with the Kaplan-Meier method. One hundred three consecutive patients (53 women; mean age 64±17 years) entered the study. Fifty-one patients were randomized to the syncope unit. For the syncope unit and standard care patients, the presumptive diagnosis was established in 34 (67%) and 5 (10%) patients ( P <0.001), respectively, hospital admission was required for 22 (43%) and 51 (98%) patients ( P <0.001), and total patient-hospital days were reduced from 140 to 64. Actuarial survival was 97% and 90% ( P =0.30), and survival free from recurrent syncope was 88% and 89% ( P =0.72) at 2 years for the syncope unit and standard care groups, respectively. Conclusions— The novel syncope unit designed for this study significantly improved diagnostic yield in the emergency department and reduced hospital admission and total length of hospital stay without affecting recurrent syncope and all-cause mortality among intermediate-risk patients. Observations from the present study provide benchmark data for improving patient care and effectively utilizing healthcare resources.

AbstractAs refinement of technetium‐99m 2‐methoxyisobutyl isonitrile‐scintigraphy (MIBI)‐scintigraphy of parathyroid glands has continued since its initial use in 1989, the sensitivity, specificity, and overall accuracy of the technique have improved greatly, approaching 100% for larger, solitary adenomas. Preoperative use of sestamibi scintigraphy has become commonplace and allows surgeons the option of a minimally invasive, or focused approach for their patients with primary hyperparathyroidism. Intraoperative use of the gamma probe based on sestamibi localization has not caught on due to lesser accuracy, cumbersome gamma probes, small doses of radiation exposure for patients and staff, and the greater accuracy and current confidence in intraoperative parathormone (PTH) monitoring. However, with the potential for smaller and more accurate gamma probes that truly assist in localizing abnormal parathyroid glands, the potential for cost reduction by shortening operative times, avoiding expensive PTH assays, and eliminating the need for pathologic analysis, gamma scintigraphy may yet become a viable option for many parathyroid surgeons.

AbstractThe etiology, prognosis, and optimal management of primary gastric carcinoids remain controversial. Records of 36 consecutive patients with gastric carcinoid (15 men) were reviewed retrospectively between 1975 and 1990. Follow‐up was complete in 97% of cases. Mean age at diagnosis was 58.4 years (range 24–82 years). The clinical presentations included anemia (72%), pain (69%), and carcinoid syndrome (11%). Associated autoimmune and endocrine abnormalities were common and included atrophic gastritis (67%), pernicious anemia (58%), hypothyroidism (39%), diabetes (19%), Addison's disease (6%), and hyperparathyroidism (6%). Lesions were nonantral in 78%, involving only the corpus in 42%, the fundus in 28%, and only the antrum in 8%; 42% were multiple. Urinary 5‐hydroxyindoleacetic acid (5‐HIAA) and serum gastrin levels were elevated in 17% and 50% of those tested, respectively. Histologic examination revealed that 28% of lesions were ≥2 cm, and 33% had liver metastases on presentation or developed them during follow‐up. Eight patients (22%) died of tumor with a median survival of 39 months. The presence of metastases, atypical histology, serosal involvement, and size > 2 cm were adverse prognostic factors. In patients without hypergastrinemia (n=6), 66% developed metastases, 60% had elevated 5‐HIAA, and 50% died of carcinoid tumor. In sharp contrast, those patients with hypergastrinemia and “typical” gastric carcinoids (n=15), metastases and death did not occur (p<0.003 and p < 0.005, respectively, compared with eugastrinemic patients). In the latter group (hypergastrinemia and typical histology), pernicious anemia was common (73%); solitary lesions and serosal penetration were seen comparatively less often (33% versus 100%, p<0.005 and 0% versus 33%, p<0.05, respectively); and no lesion measured > 2.0 cm compared to 66% in the group without elevated gastrin (p<0.002). No patient with hypergastrinaemia had elevated levels of 5‐HIAA. Overall survival at 5 and 10 years was 58% and 28%, respectively. Survival was 80% at 5 and 10 years in the hypergastrinemic group. Gastric carcinoid tumors that are histologically atypical, large (>2 cm), or present without elevated gastrin are potentially lethal and require aggressive therapy. In contrast, gastric carcinoids with typical histology and hypergastrinemia are rarely lethal, and conservative management with local excision and close observation is appropriate.

ABSTRACTSuperantigen peptide antagonists failed to block T-cell activation and cytokine production as well as toxic shock induced by staphylococcal enterotoxin B (SEB) in HLA class II transgenic mice. They also failed to inhibit the binding of SEB to HLA class II molecules as well as activation of human T lymphocytes in vitro.

AbstractAmiodarone‐associated thyrotoxicosis (AAT) is often poorly tolerated owing to underlying cardiac disease, and it is frequently refractory to conventional medical treatment. The goal of this study was to describe the patient characteristics, management, and outcomes of all the patients treated surgically for AAT at a single institution. We conducted a retrospective chart review of all patients managed surgically for AAT (April 1985 through November 2002) at the Mayo Clinic in Rochester, Minnesota. Altogether, 29 men and 5 women, ages 39 to 85 years (median 60 years), treated with amiodarone for 3 to 108 months underwent near‐total or total thyroidectomy. Frequent symptoms were worsening heart failure, fatigue, weight loss, and tremor. Altogether, 12 patients failed medical management of their AAT, and 21 received no preoperative medical therapy. One patient had been successfully managed medically but required definitive treatment. Common indications for operation were the need to remain on amiodarone, cardiac decompensation, medically refractory disease, and severe symptoms, both hyperthyroid and cardiac, necessitating prompt resolution. The median ± SD American Society of Anesthesiologists (ASA) classification (1 = healthy through 5 = moribund) was 3.00 ± 0.58. A total of 27 specimens had histology consistent with AAT. Complications included death (n = 3), rehospitalization (n = 3), symptomatic hypocalcemia (n = 2), pneumonia (n = 2), cervical hematoma (n = 1), prolonged ventilatory wean (n = 1), and stroke (n = 1); one patient developed hypotension, adult respiratory distress syndrome, and sepsis. Of the 31 surviving patients, 25 (80%) remained on amiodarone postoperatively. The median follow‐up was 29 months, at which time all surviving patients were free of hyperthyroid symptoms. Thyroidectomy is an effective treatment for AAT but has a high incidence of perioperative morbidity and mortality. The cardiovascular co‐morbidities and high operative risk in this group of patients may account for the increased complication rate.