Citations

The mitochondrial enzyme, dihydrolipoamide dehydrogenase (DLD), is essential for energy metabolism across eukaryotes. Here, conditions known to destabilize the DLD homodimer enabled the mouse, pig, or human enzyme to function as a protease. A catalytic dyad (S456–E431) buried at the homodimer interface was identified. Serine protease inhibitors and an S456A or an E431A point mutation abolished the proteolytic activity, whereas other point mutations at the homodimer interface domain enhanced the proteolytic activity, causing partial or complete loss of DLD activity. In humans, mutations in the DLD homodimer interface have been linked to an atypical form of DLD deficiency. These findings reveal a previously unrecognized mechanism by which certain DLD mutations can simultaneously induce the loss of a primary metabolic activity and the gain of a moonlighting proteolytic activity. The latter could contribute to the metabolic derangement associated with DLD deficiency and represent a target for therapies of this condition.

ABSTRACT Globoid cell leukodystrophy (GLD), also known as Krabbe disease, is a devastating, degenerative neurological disorder. It is inherited as an autosomal recessive trait caused by loss‐of‐function mutations in the galactocerebrosidase (GALC) gene. Previously, we have shown that peripheral injection of recombinant GALC, administered every other day, results in a substantial improvement in early clinical phenotype in the twitcher mouse model of GLD. While we did detect active enzyme in the brain following peripheral administration, most of the administered enzyme was localized to the periphery. Given the substantial central nervous system (CNS) involvement in this disease, we were interested in determining whether or not a single‐dose administration of the recombinant enzyme directly to the CNS, which could potentially be achieved clinically, would result in any substantial improvement. Following intracerebroventricu‐lar (icv) administration of GALC we noted a significant, 16.5%, reduction in the GALC substrate psychosine, the abnormal accumulation of which is believed to play a pivotal role in the CNS pathology observed in this disease. Moreover, recombinant GALC was found not only in periventricular regions but also at sites distant to the injection such as the cerebral cortex and cerebellum. Most importantly, animals receiving a single icv dose of the enzyme at postnatal day 20 survived up to 51 days, which compares favorably to the control twitcher animals, which normally only live to postnatal day 40/42. These results indicate that even a single icv administration of the recombinant enzyme can have significant clinical impact and suggests that other lysosomal storage disorders with significant CNS involvement may similarly benefit.—Lee, W.C., Tsoi, Y.K., Troendle, F.J., DeLucia, M.W., Ahmed, Z., Dicky, C.A., Dickson, D.W., Eckman, C.B. Single dose intracerebroventricular administration of galactocerebrosidase improves survival in a mouse model of globoid cell leukodystrophy. FASEB J. 21, 2520–2527 (2007)

Purpose To evaluate patient assessment of long-term effect of pelvic radiotherapy on bowel function. Patients and Methods As part of a prospective randomized trial evaluating the impact of sucralfate on bowel function in patients receiving pelvic radiotherapy, patient-assessed bowel function data were collected during radiotherapy and again at 4 weeks and 1 year after completion of radiotherapy. Results The number of bowel movements per day increased up to week 4 and then slowly decreased. At 1 year, the mean number of bowel movements per day had increased from 1.75 to 2.09 and the median from 1 to 2. All measures of adverse bowel function worsened during radiotherapy. Frequency of bowel movements and symptoms of frequency, nocturnal bowel movements, cramping, and bleeding returned close to baseline values by 1 year. Symptoms of urgency, clustering, and measures of incontinence were all persistent at 1 year. The mean increase in bowel function score at 1 year was 0.74 (range, −5 to 7). Conclusion Pelvic radiotherapy is associated with a slight increase in bowel movement frequency and decrease in several patient-reported measures of adverse bowel function. Several measures of adverse function persisted at 1 year.

In the present study we hypothesized that endothelial progenitor cells (EPCs) enhance production of vasoprotective substances in cerebral arteries. Isolated mononuclear cells from rabbit peripheral blood were cultured in endothelial growth medium (EGM-2) for 7 days to yield EPCs. Rabbit basilar arteries were exposed to autologous EPCs (≈5×10 5 cells) in vitro or in vivo. Twenty-four hours after intracisternal delivery of autologous EPCs, basilar arteries were isolated and expression of vasoregulatory proteins, production of prostacyclin (PGI 2 ), and cAMP were determined. Arteries transplanted with EPCs demonstrated increased protein expression of cyclooxygenase-2 and PGI 2 in adventitia, media, and endothelium. Furthermore, production of PGI 2 and arterial content of cAMP, second messenger for PGI 2 , were significantly augmented after transplantation of EPCs. In contrast, production of thromboxane A 2 was significantly reduced, whereas production of prostaglandin E 2 remained unchanged. The increased production of PGI 2 and arterial content of cAMP were inhibited only by a selective cyclooxygenase-2 inhibitor, NS-398. In vitro or in vivo treatment of basilar artery with conditioned media from EPCs also caused increase in cyclooxygenase-2 and PGI 2 synthase protein expression associated with elevation of cAMP. Our results suggest that in cerebral arteries, paracrine effect of EPCs promotes vasoprotection by increasing PGI 2 production and intracellular concentration of cAMP. This effect appears to be mediated by activation of arachidonic acid metabolism via stimulation of cyclooxygenase-2/PGI 2 synthase pathway.

To determine whether nonglucose nutrient–induced insulin secretion is impaired in pre-diabetes, subjects with impaired or normal fasting glucose were studied after ingesting either a mixed meal containing 75 g glucose or 75 g glucose alone. Despite comparable glucose areas above basal, glucose-induced insulin secretion was higher (P < 0.05) and insulin action lower (P < 0.05) during the meal than the oral glucose tolerance test (OGTT) in all subgroups regardless of whether they had abnormal or normal glucose tolerance (NGT). However, the nutrient-induced δ (meal minus OGTT) in insulin secretion and glucagon concentrations did not differ among groups. Furthermore, the decrease in insulin action after meal ingestion was compensated in all groups by an appropriate increase in insulin secretion resulting in disposition indexes during meals that were equal to or greater than those present during the OGTT. In contrast, disposition indexes were reduced (P < 0.01) during the OGTT in the impaired glucose tolerance groups, indicating that reduced glucose induced insulin secretion. We conclude that, whereas glucose-induced insulin secretion is impaired in people with abnormal glucose tolerance, nonglucose nutrient–induced secretion is intact, suggesting that a glucose-specific defect in the insulin secretory pathway is an early event in the evolution of type 2 diabetes.

The purpose of this study was to evaluate the cost-effectiveness of routine wrist radiography in the evaluation of patients with a wrist ganglion. In the setting of a University-based hand surgery practice, 103 consecutive patients with a dorsal or volar wrist ganglion underwent posteroanterior, lateral, and oblique radiographs of the involved wrist. There were 24 men and 79 women with an average age of 34 years (range 4–67 years). A retrospective review of the medical records was performed. Abnormalities on plain radiographs were noted in only 13 patients (13%). Findings included six cases of thumb carpometacarpal joint arthritis and one case each of an enchondroma, congenital distal radioulnar joint (DRUJ) anomaly, DRUJ degenerative changes, intraosseous ganglion, carpal boss, radiocarpal arthritis, and thumb metacarpophalangeal joint osteoarthritis. In only one case (1%) did the findings alter the management. At our institution, the professional and technical charge for three views of the wrist is $172. This confers a cost of $17,716 per therapeutically significant finding in our series. We conclude that routinely performing wrist radiography is not cost-effective in the evaluation and treatment decision-making process in patients with a wrist ganglion.

Abstract Recent evidence suggests that there is etiologic heterogeneity among the various subtypes of lymphoid neoplasms. However, epidemiologic analyses by disease subtype have proven challenging due to the numerous clinical and pathologic schemes used to classify lymphomas and lymphoid leukemias over the last several decades. On behalf of the International Lymphoma Epidemiology Consortium (InterLymph) Pathology Working Group, we present a proposed nested classification of lymphoid neoplasms to facilitate the analysis of lymphoid neoplasm subtypes in epidemiologic research. The proposed classification is based on the World Health Organization classification of lymphoid neoplasms and the International Classification of Diseases–Oncology, Third Edition (ICD-O-3). We also provide a translation into the proposed classification from previous classifications, including the Working Formulation, Revised European-American Lymphoma (REAL) classification, and ICD-O-2. We recommend that epidemiologic studies include analyses by lymphoma subtype to the most detailed extent allowable by sample size. The standardization of groupings for epidemiologic research of lymphoma subtypes is essential for comparing subtype-specific reports in the literature, harmonizing cases within a single study diagnosed using different systems, as well as combining data from multiple studies for the purpose of pooled analysis or meta-analysis, and will probably prove to be critical for elucidating etiologies of the various lymphoid neoplasms.