Efficacy of empirical cardiac pacing in syncope of unknown cause.

Cardiac pacing is often considered in patients with recurrent syncope after repeated attempts to document the cause have failed. To assess the results of this tactic we reviewed the records of 104 patients who had received pacemakers for known or suspected bradycardia between September 1973 and March 1985. The patients were classified retrospectively into three groups: group 1 (31 patients with a mean age of 73 years) had unequivocal documentation of bradycardia during syncope, group 2 (42 patients with a mean age of 71 years) had electrocardiographic or electrophysiologic evidence of potential bradycardia but no documentation during spontaneous syncope, and group 3 (31 patients with a mean age of 69 years) had a history "suggestive of" bradycardia-related syncope but no other evidence to support the diagnosis. The rates of recurrence of syncope during follow-up were 6.3%, 7.3% and 32.2% in groups 1, 2 and 3 respectively (p less than 0.01). In group 3 recurrence was more probable in patients with loss of consciousness for more than 2 minutes than in those who were unconscious for 2 minutes or less (p less than 0.05). The results suggest that pacemaker implantation is justified for recurrent syncope after extensive attempts to document a spell have failed if abnormal diagnostic test results suggest bradycardia as a possible cause. Empirical pacing is less satisfactory in patients with normal results of evaluation but may arguably be justified when patients have recurrent syncope with injury.     

Arterial endothelial function in a porcine model of early stage atherosclerotic vascular disease

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in the United States and is projected to become the leading cause of mortality in the world. Atherosclerosis is the most important single factor contributing to this disease burden. In this study, we characterize relationships between endothelial dysfunction and vascular disease in an animal model of diet-induced, early-stage atherosclerotic vascular disease. We tested the hypothesis that hypercholesterolaemia induces vascular disease and impairs endothelium-dependent relaxation (EDR) in conduit arteries of adult male Yucatan pigs. Pigs were fed a normal fat (NF) or high fat cholesterol (HFC) diet for 20-24 weeks. Results indicate that, while the HFC diet did not alter EDR in femoral or brachial arteries, EDR was significantly decreased in both carotid and coronary arteries. Sudanophilic fatty streaks were significantly present in the abdominal aorta and common carotid artery. Histopathology revealed increased intima-media thickness (IMT) and foam cell accumulation in Stary Stage I-III lesions in the abdominal aorta, common carotid artery and femoral arteries. In the coronary arteries, the accumulation of foam cells in Stary Stage I and II lesions resulted in a trend for increased IMT. There was no evidence of vascular disease in the brachial arteries. These results indicate that early stages of CVD (Stary Stage I-III) precede decreases in EDR induced by HFC diet, because femoral arteries exhibited foam cell accumulation and an increased IMT but no change in endothelial function.     

Silencing the major apple allergen Mal d 1 by using the RNA interference approach

BACKGROUND: Apple allergy is dominated by IgE antibodies against Mal d 1 in areas where birch pollen is endemic. Apples with significantly decreased levels of Mal d 1 would allow most patients in these areas to eat apples without allergic reactions. OBJECTIVE: The aim of this study was to inhibit the expression of Mal d 1 in apple plants by RNA interference. METHODS: In vitro -grown apple plantlets were transformed with a construct coding for an intron-spliced hairpin RNA containing a Mal d 1-specific inverted repeat sequence separated by a Mal d 1-specific intron sequence. The presence of the construct in transformants was checked by PCR. Expression of Mal d 1 in leaves was monitored by prick-to-prick skin testing in 3 patients allergic to apples and by immunoblotting with a Mal d 1-reactive mAb and with IgE antibodies against Mal d 1. RESULTS: After transformation, plantlets were selected on the basis of having a normal phenotype and growth rate. With PCR, in 6 of 9 selected plantlets, the presence of the gene-silencing construct was demonstrated. By skin prick test it was shown that a wild-type plantlet had significantly ( P < .05) higher allergenicity than 5 of the transformants. Reduction of expression of Mal d 1 was confirmed by immunoblotting. In wild-type and unsuccessful transformants, a strong band was detected with Mal d 1-reactive mAb 5H8 at the expected apparent M r of 17 kDa. This band was virtually absent in the transformants that carried the gene-silencing construct. With human IgE antibodies, the same observations were made. CONCLUSIONS: Mal d 1 expression was successfully reduced by RNA interference. This translated into significantly reduced in vivo allergenicity. These observations support the feasibility of the production by gene silencing of apples hypoallergenic for Mal d 1.     

Automated Recognition of Lateral from PA Chest Radiographs: Saving Seconds in a PACS Environment

Images acquired in a two-view digital chest examination are frequently not electronically distinguishable. As a result the lateral and posterioanterio (PA) images are often improperly positioned on a PACS work station. A series of 1998 chest radiographs (999 lateral, 999 PA or AP) were used to develop a neural network classifier. The images were down-sampled to 16 × 16 matrices, and a feed-forward neural network was trained and tested using the leave-one-out method. Using five nodes in the hidden layer, the neural network correctly identified 987 of the 999 test cases (98.8%) (average of six runs). The simple architecture and speed of this technique suggests that it would be a useful addition to PACS work station software. The accumulated time saved by correctly positioning the lateral and PA chest images on the work station monitors in accordance with each radiologists hanging protocols was estimated to be about 1 week of radiologist time per year.     

Inducible Nitric Oxide Synthase Does Not Affect Resolution of Murine Chlamydial Genital Tract Infections or Eradication of Chlamydiae in Primary Murine Cell Culture

Mice lacking inducible nitric oxide synthase (iNOS) or treated with iNOS inhibitors resolved chlamydial genital tract infections. Additionally, treatment of primary murine cell cultures with gamma interferon restricted chlamydial growth in the absence of nitric oxide. From these results, iNOS activity is unnecessary for the resolution of chlamydial genital tract infections in mice and inhibition of chlamydial growth in culture.     

Immunohistochemical characterization of amyloid proteins in sural nerves and clinical associations in amyloid neuropathy.

To test whether immunohistochemical characterization of proteins in amyloid deposits in biopsied sural nerves gives reliable and useful diagnostic information using commercially available reagents, biopsy specimens of sural nerves from 38 patients with amyloid neuropathy were studied. Transthyretin (TTR) was detected in the amyloid deposits of 11 nerves, lambda light chains (LC) in 8 nerves, kappa LC in 7 nerves, and both lambda and kappa LC in 3 nerves. In 9 nerves, the amyloid deposits were too small to allow adequate immunohistochemical characterization of amyloid proteins in serial sections. Evidence that immunohistochemical characterization was correct came from: 1) evaluation of kin, 2) search for monoclonal proteins in the plasma, and 3) sequencing of the gene abnormalities in TTR+ cases. In 9 of 11 TTR+ cases, in which DNA could be obtained, sequencing of the gene showed that each of the 9 cases was heterozygous for a gene mutation; 7 had previously described mutations and 2 undescribed mutations. Therefore, in the nine sporadic cases without plasma monoclonal light chains, the immunohistochemical characterization correctly identified the protein in amyloid as transthyretin. Likewise, there was a high concordance between immunoglobulin light chains in plasma and light chains in amyloid in primary amyloidosis. Evaluation of the type, distribution, and severity of the neurologic symptoms and deficits showed: 1) the sensorimotor and autonomic neuropathy of amyloidosis characteristically affects proximal as well as distal limbs, and 2) the type of amyloidosis probably cannot be determined from the characteristics or severity of the neuropathy alone or from the location or size of amyloid deposits in nerve.     

Effects of gastrointestinal candidiasis, antibiotics, dietary arabinitol, and cortisone acetate on levels of the Candida metabolite D-arabinitol in rat serum and urine.

We studied the effects of gastrointestinal (GI) colonization by Candida albicans, dietary arabinitol, intragastric antibiotics, and cortisone on levels of the Candida metabolite D-arabinitol in rat serum and urine. Rats given conventional laboratory chow, intragastric gentamicin and chloramphenicol, and 6.0 x 10(8) live C. albicans B311 blastoconidia by gavage had minimal invasive GI disease and no more DL-arabinitol in the urine than controls given killed C. albicans. However, colonized and uncolonized rats given intragastric antibiotics had transiently higher urine arabinitol levels than the corresponding controls given saline. Rats given conventional laboratory chow (which contained 50 micrograms of arabinitol per g) had higher serum and urine arabinitol levels than rats given no dietary arabinitol, but the differences were less than expected. Moreover, intragastric antibiotics did not cause increased arabinitol excretion in rats given no dietary arabinitol. Rats given intragastric antibiotics and live C. albicans but no dietary arabinitol had no more arabinitol in their serum or urine than controls given antibiotics and killed C. albicans or saline and live or killed C. albicans. Lastly, cortisone acetate (10 mg/kg of body weight per day intramuscularly for 10 days) did not cause increased serum or urine arabinitol levels. We conclude that neither GI colonization by C. albicans nor cortisone should interfere with the usefulness of arabinitol as a marker for invasive candidiasis; antibiotics appear to increase arabinitol excretion by suppressing GI bacteria capable of consuming dietary arabinitol.     

Pulmonary marginal zone lymphoma of MALT type as a cause of localised pulmonary amyloidosis

AIM: To describe six patients with pulmonary marginal zone lymphoma in whom amyloid deposition was identified. Marginal zone lymphoma is a recently recognised type of low grade non-Hodgkin's lymphoma. METHODS: A computerised search was performed of all patients seen at the Mayo Clinic with a diagnosis of pulmonary amyloidosis. Six patients with pulmonary amyloidosis who had biopsy confirmed extranodal marginal zone lymphoma of mucosa associated lymphoid tissue type were identified. All were women, ranging in age from 45 to 85 years. RESULTS: Five patients had amyloid deposition in conjunction with pulmonary marginal zone lymphoma at the time of the original diagnosis. One patient was referred for evaluation of localised pulmonary amyloidosis and was found to have coexisting pulmonary marginal zone lymphoma. Clinical presentation was limited to pulmonary symptoms (two of the six) or constitutional symptoms (two), or was asymptomatic (two). In all six cases, initial findings of nodular densities on screening chest roentgenograms led to further evaluation and eventual lobectomy; these findings included multiple pulmonary nodules (four), single nodule (one), and single nodule with diffuse bilateral interstitial infiltrates (one). Bone marrow was examined in five patients and was normal in all. Protein studies performed in four patients revealed no monoclonal protein. No patients had manifestations of systemic amyloidosis, such as renal, neurological, or cardiac involvement, at a median follow up of 50 months. Four of the six patients remain alive at a median of five years. CONCLUSIONS: Pulmonary marginal zone lymphoma may be found in association with localised amyloid deposition and should be considered in the differential diagnosis of localised pulmonary amyloidosis.