Hereditary and Sporadic Papillary Renal Carcinomas with c-met Mutations Share a Distinct Morphological Phenotype

Germline mutations of c-met oncogene at 7q31 have been detected in patients with hereditary papillary renal cell carcinoma. In addition, c-met mutations were shown to play a role in 13% of patients with papillary renal cell carcinoma and no family history of renal tumors. The histopathology of papillary renal cell carcinoma with c-met mutations has not been previously described. We analyzed the histopathology of 103 bilateral archival papillary renal cell carcinomas and 4 metastases in 29 patients from 6 hereditary papillary renal cell carcinoma families with germline c-met mutations and 6 papillary renal cell carcinomas with c-met mutations from 5 patients with no family history of renal tumors. Twenty-five sporadic renal tumors with prominent papillary architecture and without somatic c-met mutations were evaluated for comparison. All papillary renal cell carcinomas with c-met mutations were 75 to 100% papillary/tubulopapillary in architecture and showed chromophil basophilic, papillary renal cell carcinoma type 1 histology. Fuhrman nuclear grade 1-2 was seen in tumors from 23 patients, and nuclear grade 3 was observed focally in 8 patients. Seventeen patients had multiple papillary adenomas and microscopic papillary lesions in the surrounding renal parenchyma. Clear cells with intracytoplasmic lipid and glycogen were focally present in tumors of 94% papillary renal cell carcinoma patients. Clear cells of papillary renal cell carcinoma had small basophilic nuclei, and clear cell areas lacked a fine vascular network characteristic of conventional (clear) cell renal cell carcinoma. We conclude that papillary renal cell carcinoma patients with c-met mutations develop multiple, bilateral, papillary macroscopic and microscopic renal lesions. Renal tumors with c-met genotype show a distinctive papillary renal cell carcinoma type 1 phenotype and are genetically and histologically different from renal tumors seen in other hereditary renal syndromes and most sporadic renal tumors with papillary architecture. Although all hereditary and sporadic papillary renal cell carcinomas with c-met mutations share papillary renal cell carcinoma type 1 histology, not all type 1 sporadic papillary renal cell carcinomas harbor c-met mutations.     

Depressive symptoms in patients with obstructive sleep apnea: biological mechanistic pathways

This study examined the association between depressive symptoms, as well as depressive symptom dimensions, and three candidate biological pathways linking them to Obstructive sleep apnea (OSA): (1) inflammation; (2) circulating leptin; and (3) intermittent hypoxemia. Participants included 181 obese adults with moderate-to-severe OSA enrolled in the Cardiovascular Consequences of Sleep Apnea (COSA) trial. Depressive symptoms were measured using the Beck Depression Inventory-II (BDI-II). We assessed inflammation using C-reactive protein levels (CRP), circulating leptin by radioimmunoassay using a double antibody/PEG assay, and intermittent hypoxemia by the percentage of sleep time each patient had below 90% oxyhemoglobin saturation. We found no significant associations between BDI-II total or cognitive scores and CRP, leptin, or percentage of sleep time below 90% oxyhemoglobin saturation after controlling for relevant confounding factors. Somatic symptoms, however, were positively associated with percentage of sleep time below 90% saturation (β = 0.202, P = 0.032), but not with CRP or circulating leptin in adjusted models. Another significant predictor of depressive symptoms included sleep efficiency (β_{BDI Total} = ?0.230, P = 0.003; β_cognitive = ?0.173, P = 0.030 (β_somatic = -0.255, P = 0.001). In patients with moderate-to-severe OSA, intermittent hypoxia may play a role in somatic rather than cognitive or total depressive symptoms.     

Case-control study of subjective and objective differences in sleep patterns in older adults with insomnia symptoms

Older adults have high prevalence rates of insomnia symptoms, yet it is unclear if these insomnia symptoms are associated with objective impairments in sleep. We hypothesized that insomnia complaints in older adults would be associated with objective differences in sleep compared with those without insomnia complaints. To test this hypothesis, we conducted a cross‐sectional study in which older adults with insomnia complaints (cases, n = 100) were compared with older adults without insomnia complaints (controls, n = 100) using dual‐night in‐lab nocturnal polysomnography, study questionnaires and 7 days of at‐home actigraphy and sleep diaries. Cases were noted to have reduced objective total sleep time compared with controls (25.8 ± 8.56 min, P = 0.003). This was largely due to increased wakefulness after sleep onset, and not increased sleep latency. When participants with sleep‐related breathing disorder or periodic limb movement disorder were excluded, the polysomnography total sleep time difference became even larger. Cases also had reduced slow‐wave sleep (5.10 ± 1.38 min versus 10.57 ± 2.29 min, effect size −0.29, P = 0.04). When comparing self‐reported sleep latency and sleep efficiency with objective polysomnographic findings, cases demonstrated low, but statistically significant correlations, while no such correlations were observed in controls. Cases tended to underestimate their sleep efficiency by 1.6% (±18.4%), while controls overestimated their sleep efficiency by 12.4% (±14.5%). In conclusion, we noted that older adults with insomnia complaints have significant differences in several objective sleep findings relative to controls, suggesting that insomnia complaints in older adults are associated with objective impairments in sleep.     

Contrast sensitivity of MT receptive field centers and surrounds

Neurons throughout the visual system have receptive fields with both excitatory and suppressive components. The latter are responsible for a phenomenon known as surround suppression, in which responses decrease as a stimulus is extended beyond a certain size. Previous work has shown that surround suppression in the primary visual cortex depends strongly on stimulus contrast. Such complex center-surround interactions are thought to relate to a variety of functions, although little is known about how they affect responses in the extrastriate visual cortex. We have therefore examined the interaction of center and surround in the middle temporal (MT) area of the macaque (Macaca mulatta) extrastriate cortex by recording neuronal responses to stimuli of different sizes and contrasts. Our findings indicate that surround suppression in MT is highly contrast dependent, with the strongest suppression emerging unexpectedly at intermediate stimulus contrasts. These results can be explained by a simple model that takes into account the nonlinear contrast sensitivity of the neurons that provide input to MT. The model also provides a qualitative link to previous reports of a topographic organization of area MT based on clusters of neurons with differing surround suppression strength. We show that this organization can be detected in the gamma-band local field potentials (LFPs) and that the model parameters can predict the contrast sensitivity of these LFP responses. Overall our results show that surround suppression in area MT is far more common than previously suspected, highlighting the potential functional importance of the accumulation of nonlinearities along the dorsal visual pathway.     

Heart rate variability during wakefulness as a marker of obstructive sleep apnea severity

Study ObjectivesPatients with obstructive sleep apnea (OSA) exhibit heterogeneous heart rate variability (HRV) during wakefulness and sleep. We investigated the influence of OSA severity on HRV parameters during wakefulness in a large international clinical sample.Methods1247 subjects (426 without OSA and 821 patients with OSA) were enrolled from the Sleep Apnea Global Interdisciplinary Consortium. HRV parameters were calculated during a 5-minute wakefulness period with spontaneous breathing prior to the sleep study, using time-domain, frequency-domain and nonlinear methods. Differences in HRV were evaluated among groups using analysis of covariance, controlling for relevant covariates.ResultsPatients with OSA showed significantly lower time-domain variations and less complexity of heartbeats compared to individuals without OSA. Those with severe OSA had remarkably reduced HRV compared to all other groups. Compared to non-OSA patients, those with severe OSA had lower HRV based on SDNN (adjusted mean: 37.4 vs. 46.2 ms; p < 0.0001), RMSSD (21.5 vs. 27.9 ms; p < 0.0001), ShanEn (1.83 vs. 2.01; p < 0.0001), and Forbword (36.7 vs. 33.0; p = 0.0001). While no differences were found in frequency-domain measures overall, among obese patients there was a shift to sympathetic dominance in severe OSA, with a higher LF/HF ratio compared to obese non-OSA patients (4.2 vs. 2.7; p = 0.009).ConclusionsTime-domain and nonlinear HRV measures during wakefulness are associated with OSA severity, with severe patients having remarkably reduced and less complex HRV. Frequency-domain measures show a shift to sympathetic dominance only in obese OSA patients. Thus, HRV during wakefulness could provide additional information about cardiovascular physiology in OSA patients.Clinical Trial Information: A Prospective Observational Cohort to Study the Genetics of Obstructive Sleep Apnea and Associated Co-Morbidities (German Clinical Trials Register - DKRS, DRKS00003966) https://www.drks.de/drks_web/navigate.do?navigationId=trial.HTML&TRIAL_ID=DRKS00003966     

Molecular cloning and mutagenesis of a DNA locus involved in lipooligosaccharide biosynthesis in Haemophilus somnus

Haemophilus somnus undergoes antigenic and structural phase variation in its lipooligosaccharide (LOS). A gene (lob-1) containing repetitive 5'-CAAT-3' sequences that may, in part, contribute to phase variation was cloned and sequenced (T. J. Inzana et al., Infect. Immun. 65:4675-4681, 1997). We have now identified another putative gene (lob-2A) immediately upstream from lob-1. Lob-2A contained homology to several LOS biosynthesis proteins of the family Pasteurellaceae and the LgtB and LgtE galactosyltransferases of Neisseria meningitidis and N. gonorrhoeae. Unlike lob-1, lob-2A contained 18 to 20 5'-GA-3' repeats 141 bp upstream of the termination codon as determined by PCR amplification of DNA from individual colonies. Twenty repeats were most common, but when 19 5'-GA-3' repeats were present a stop codon would occur 1 bp after the last 5'-GA-3' repeat. A 630-bp SalI-BsgI fragment within lob-2A was deleted, and a kanamycin resistance (Km(r)) gene was inserted into this site to create pCAATDeltalob2A. Following electroporation of pCAATDeltalob2A into H. somnus 738, several allelic exchange mutants were isolated. The LOS electrophoretic profile of one mutant, strain 738-lob2A1::Km, was altered, and the phase variation rate was reduced but phase variation was not eliminated. A variant with 19 5'-GA-3' repeats in lob-2A had an LOS profile similar to that of 738-lob2A1::Km, suggesting that lob-2A was turned off in this phase. Nanoelectrospray mass spectrometry (nES-MS) and nuclear magnetic resonance spectroscopy showed that 738-lob2A1::Km was deficient in the terminal betaGal(1-3)betaGlcNAc residue present in parent strain 738. Mutant 738-lob2A1::Km was significantly more sensitive to the bactericidal action of normal bovine serum and was less virulent in mice than was parent strain 738. When H. somnus 129Pt was electrotransformed with shuttle vector pLS88 containing lob-2A, its LOS electrophoretic profile was modified and additional N-acetylhexosamine residues were present, as determined by nES-MS analysis. These results indicated that lob-2A may be an N-acetylglucosamine transferase involved in LOS biosynthesis and phase variation and that LOS structure is important to H. somnus virulence.     

Differential effects of the antioxidant alpha-lipoic acid on the proliferation of mitogen-stimulated peripheral blood lymphocytes and leukaemic T cells

The effects of the antioxidant alpha-lipoic acid (LA) on the proliferation of mitogen-stimulated human peripheral blood lymphocytes (HPBL) were investigated in comparison to its effects on the proliferation of two leukaemic T cell lines, Jurkat and CCRF-CEM. At low mM concentrations, LA inhibited in a dose-dependent manner DNA synthesis of HPBL stimulated with either phorbol myristate acetate (PMA) in combination with ionomycin (IoM), or phytohaemagglutinin (PHA). At similar concentrations, LA inhibited the proliferation of Jurkat and CCRF-CEM cells. However, LA was preferentially cytotoxic to the leukaemic cell lines. The selective toxicity of LA to Jurkat cells was shown by electron microscopy (EM) to be due to the induction of apoptosis. Furthermore, LA had different effects on the secretion of interleukin-2 (IL-2) and steady-state levels of IL-2 mRNA in mitogen-stimulated HPBL depending on the mitogens used. LA dramatically increased the induction of IL-2 mRNA and IL-2 protein secretion in PMA/IoM-stimulated HPBL, whereas it inhibited these in HPBL stimulated with PHA. The differential effects of LA on normal and leukaemic T lymphocytes may indicate a new route towards development of therapeutic agents.     

Dendritic cells in the T-cell areas of lymphoid organs

Summary: Substantial numbers of dendritic cells (DCs) are found in the T-cell areas of peripheral lymphoid organs such as the spleen, lymph node and Peyer's patch. By electron microscopy these DCs (also called interdigitating cells) form a network through which T cells continually recirculate. The cytological features of DCs in the T-cell areas, as well as a number of markers detected with monoclonal antibodies, are similar to mature DCs that develop from other sites such as skin and bone marrow. Some markers that are expressed in abundance are: MHC II and the associated invariant chain, accessory molecules such as CD40 and CD86, a multilectin receptor for antigen presentation called DEC-205, the integrin CD11c, several antigens within the endocytic system that are detected by monoclonal anti-bodies but are as yet uncharacterized at the molecular level, and, in the human system, molecules termed Sl00b, CD83 and p55. DCs in the periphery can pick up antigens and migrate to the T-cell areas to initiate immunity However, there are new observations that DCs within the T-cell areas also express high levels of self-antigens and functional fas-ligand capable of Inducing CD4⁺ T-cell death. We speculate that there are at least 2 sets of DCs in the T-cell areas, a migratory myeloid pathway that brings in antigens from the periphery and induces immunity, and a more resident lymphoid pathway that presents self-antigens and maintains tolerance.     

Cytogenetic,spectral karyotyping,fluorescence in situ hybridization,and comparative genomic hybridization characterization of two new secondary leukemia cell lines with 5q deletions,and MYC and MLL amplification

Cytogenetic studies of patients with therapy-induced acute myeloid leukemia (t-AML) have demonstrated whole chromosome loss or q-arm deletion of chromosomes 5 and/or 7 in a majority of cases. We have established two cell lines, SAML-1 and SAML-2, from two patients who developed t-AML after radiation and chemotherapy for Hodgkin disease. In both cases, the leukemia cells contained 5q deletions. SAML-1 has 58 chromosomes and numerous abnormalities, including der(1)(1qter-->1p22::5q31-->5qter), der(5)(5pter-->5q22::1p22-->1pter), +8, der(13)i(13)(q10)del(13)(q11q14.1), and t(10;11). Fluorescence in situ hybridization (FISH) with unique sequence probes for the 5q31 region showed loss of IL4, IL5, IRF1, and IL3, and translocation of IL9, DS5S89, EGR1, and CSFIR to 1p. SAML-2 has 45 chromosomes, del(5)(q11.2q31) with a t(12;13)ins(12;5), leading to the proximity of IRF1 and RB1, and complex translocations of chromosomes 8 and 11, resulting in amplification of MYC and MLL. Comparative genomic hybridization and spectral karyotyping were consistent with the G-banding karyotype and FISH analyses. Because a potential tumor suppressor(s) in the 5q31 region has yet to be identified, these cell lines should prove useful in the study of the mechanisms leading to the development of t-AML.