Modified Dynamic CT Myelography for Type 1 and 2 CSF Leaks: A Procedural Approach

BACKGROUND AND PURPOSE

Dynamic CT myelography can identify spinal CSF leaks secondary to dural tears (type 1) and ruptured meningeal diverticula (type 2), but the radiation can be high secondary to multiple successive acquisitions. The purpose of this article is to discuss the procedural approach of a modified dynamic CT myelography technique with single scan acquisitions, reduced contrast volume, and condensed scan coverage and compare its radiation dose with that in traditional dynamic CT myelography.

MATERIALS AND METHODS

Retrospective review was performed for patients with spontaneous CSF leaks showing extradural collections on spine MR imaging who underwent traditional and modified dynamic CT myelography. The radiation doses between the 2 cohorts were compared.

RESULTS

Thirty-seven patients (25 women, 12 men) had a type 1 or 2 CSF leak on dynamic CT myelography. Thirty-one patients had a type 1 CSF leak, and 6 patients had type 2 leaks. The traditional dynamic CT myelography was performed in 25 patients, and the average number of acquisitions per dynamic CT myelography was 3.6. The mean total effective dose per dynamic CT myelography was 31.3 mSv (range, 11.3-68.4 mSv). The modified dynamic CT myelography was performed in 12 patients, and the average number of acquisitions was 2.8. The mean total effective dose per dynamic CT myelography was 15.1 mSv (range, 4.8-24.6 mSv). The effective dose and dose-length product between the cohorts were statistically significant (P  < .0001 and .01, respectively).

CONCLUSIONS

Modified dynamic CT myelography performed with single scan acquisitions, smaller volume of contrast, and reduced scan coverage can reduce the radiation dose for type 1 and 2 CSF leak detection.

Spontaneous Spinal CSF Leaks Stratified by Age, Body Mass Index, and Spinal Level

BACKGROUND AND PURPOSE

There are 3 main types of spinal CSF leaks, and the imaging appearances are well-reported. Specific patient demographics and spinal locations of the various types of spinal leaks are less frequently described. The purpose of this article was to stratify the various types of spontaneous CSF leaks on the basis of age, body mass index, and spinal level.

MATERIALS AND METHODS

Retrospective review was performed for all patients with spontaneous spinal CSF leaks identified on CT myelography. Age, body mass index, and spinal CSF leak type and level were recorded.

RESULTS

Sixty-five patients (37 women and 28 men) had spinal CSF leaks. Type 1 CSF leaks (dural tears) were observed in 25 patients (mean age, 44.5 years; mean body mass index, 24.3) and were most common in the upper thoracic spine (72%), particularly at the T1-T2 level (36%). Type 2 CSF leaks (ruptured meningeal diverticula) were observed in 4 patients (mean age, 45.5 years; mean body mass index, 27.5) and were all seen in the lower thoracic spine. Type 3 CSF leaks (CSF-venous fistulas) were observed in 36 patients (mean age, 58.8 years; mean body mass index, 27.0) and were most common on the right side (72%) and in the lower thoracic spine (56%).

CONCLUSIONS

Type 1 CSF leaks occurred in younger patients with a normal body mass index, while patients with type 3 CSF leaks were relatively older and had an elevated body mass index. Type 1 leaks mostly occurred in the upper thoracic spine, and types 2 and 3 leaks mostly occurred in the lower thoracic spine.

Decubitus CT Myelography for CSF-Venous Fistulas: A Procedural Approach

Decubitus CT myelography is a reported method to identify CSF-venous fistulas in patients with spontaneous intracranial hypotension. One of the main advantages of decubitus CT myelography in detecting CSF-venous fistulas is using gravity to dependently opacify the CSF-venous fistula, which can be missed on traditional myelographic techniques. Most of the CSF-venous fistulas in the literature have been identified in patients receiving general anesthesia and digital subtraction myelography, a technique that is not performed at all institutions. In this article, we discuss the decubitus CT myelography technique and how to implement it in daily practice.

[The clinicopathological characteristics of diabetic nephropathy and non-diabetic renal diseases in diabetic patients]

Objective: To analyze the clinicopathological characteristics of renal lesions in type 2 diabetic patients and to differentiate diabetic nephropathy (DN) from non-diabetic renal diseases(NDRD). Methods: Type 2 diabetic patients who received renal biopsy in Ruijin Hospital from January 2011 to December 2015 were recruited in this study. Clinical history, laboratory results and pathological data were retrospectively collected. According to the pathological findings, the patients were divided into 3 groups: DN, NDRD, DN+NDRD. Logistic model was applied to explore the independent clinical predictive factors in differentiating DN from NDRD. Results: A total of 207 type 2 diabetic patients received renal biopsy, accounting for 6.82% of all biopsy population. Fifty-one patients were diagnosed with DN, 142 with NDRD and 14 with both DN and NDRD. In NDRD, membranous nephropathy(MN)(34.5%) was the most common finding, followed by IgA nephropathy(19.7%).By contrast, NDRD patients manifested a shorter diabetic course, a higher baseline hemoglobin level, a lower baseline serum creatinine, a higher prevalence of hematuria, a lower prevalence of hypertension and diabetic retinopathy, a better control of blood glucose, better compliance of monitoring blood glucose and less family history of diabetes. In multivariate logistic model, diabetic family history(OR=4.68, P=0.04) and long history of diabetes(OR=1.01, P=0.02) were risk factors of DN. Conclusion: There is a high prevalence of NDRD in diabetic patients with renal lesions. Family history of diabetes and duration of diabetes are independent predictors of DN.

Receptor for activated C kinase 1 (RACK1) inhibits function of transient receptor potential (TRP)-type channel Pkd2L1 through physical interaction

Pkd2L1 (also called TRPP3) is a non-selective cation channel permeable to Ca(2+), Na(+), and K(+) and is activated by Ca(2+). It is also part of an acid-triggered off-response cation channel complex. We previously reported roles of the Pkd2L1 C-terminal fragments in its channel function, but the role of the N terminus remains unclear. Using a yeast two-hybrid screening, we found that the Pkd2L1 N terminus interacts with the receptor for activated C kinase 1 (RACK1), a scaffolding/anchoring protein implicated in various cellular functions. This interaction requires the last two Trp-Asp (WD) motifs of RACK1 and fragment Ala(19)-Pro(45) of Pkd2L1. The interaction was confirmed by GST pulldown, blot overlay, and co-immunoprecipitation assays. By (45)Ca tracer uptake and two-microelectrode voltage clamp electrophysiology, we found that in Xenopus oocytes with RACK1 overexpression Pkd2L1 channel activity is abolished or substantially reduced. Combining with oocyte surface biotinylation experiments, we demonstrated that RACK1 inhibits the function of Pkd2L1 channel on the plasma membrane in addition to reducing its total and plasma membrane expression. Overexpressing Pkd2L1 N- or C-terminal fragments as potential blocking peptides for the Pkd2L1-RACK1 interaction, we found that Pkd2L1 N-terminal fragment Met(1)-Pro(45), but not Ile(40)-Ile(97) or C-terminal fragments, abolishes the inhibition of Pkd2L1 channel by overexpressed and oocyte-native RACK1 likely through disrupting the Pkd2L1-RACK1 association. Taken together, our study demonstrated that RACK1 inhibits Pkd2L1 channel function through binding to domain Met(1)-Pro(45) of Pkd2L1. Thus, Pkd2L1 is a novel target channel whose function is regulated by the versatile scaffolding protein RACK1.

Direct binding of alpha-actinin enhances TRPP3 channel activity

Transient receptor potential (TRP) polycystin 2 and 3 (TRPP2 and 3) are homologous members of the TRP superfamily of cation channels but have different physiological functions. TRPP2 is part of a flow sensor, and is defective in autosomal dominant polycystic kidney disease and implicated in left-right asymmetry development. TRPP3 is reported to implicate in sour tasting in bipolar cells of taste buds of the tongue and in the regulation of pH-sensitive action potential in neurons surrounding the central canal of spinal cord. TRPP3 is present in both excitable and non-excitable cells in various tissues, such as retina, brain, heart, testis, and kidney, but its common and cell type-specific functional characteristics remain largely unknown. In this study, we investigated physical and functional interactions between TRPP3 and alpha-actinin, an actin-bundling protein known to regulate several types of ion channels. We employed planer lipid bilayer electrophysiology system to study the function of TRPP3 channel that was affinity-purified from Madin-Darby canine kidney cells. Upon reconstitution in bilayer, TRPP3 exhibited cation channel activities that were substantially augmented by alpha-actinin. The TRPP3-alpha-actinin association was documented by co-immunoprecipitation using native cells and tissues, yeast two-hybrid, and in vitro binding assays. Further, TRPP3 was abundantly present in mouse brain where it associates with alpha-actinin-2. Taken together, alpha-actinin not only attaches TRPP3 to the cytoskeleton but also up-regulates TRPP3 channel function. It remains to be determined whether the TRPP3-alpha-actinin interaction is relevant to acid sensing and other functions in neuronal and non-neuronal cells.

Alpha-actinin associates with polycystin-2 and regulates its channel activity

Polycystin-2 (PC2) is the product of the PKD2 gene, which is mutated in 10-15% patients of autosomal dominant polycystic kidney disease (ADPKD). PC2 is an integral transmembrane protein and acts as a calcium-permeable cation channel. The functional modulation of this channel by other protein partners remains largely unknown. In the present study, using a yeast two-hybrid approach, we discovered that both intracellular N- and C-termini of PC2 associate with alpha-actinins, actin-binding and actin-bundling proteins important in cytoskeleton organization, cell adhesion, proliferation and migration. The PC2-alpha-actinin association was confirmed by in vitro glutathione S-transferase pull-down and dot blot overlay assays. In addition, the in vivo interaction between endogenous PC2 and alpha-actinins was demonstrated by co-immunoprecipitation in human embryonic kidney 293 and Madin-Darby canine kidney (MDCK) cells, rat kidney and heart tissues and human syncytiotrophoblast (hST) apical membrane vesicles. Immunofluorescence experiments showed that PC2 and alpha-actinin were partially co-localized in epithelial MDCK and inner medullary collecting duct cells, NIH 3T3 fibroblasts and hST vesicles. We studied the functional modulation of PC2 by alpha-actinin in a lipid bilayer electrophysiology system using in vitro translated PC2 and found that alpha-actinin substantially stimulated the channel activity of reconstituted PC2. A similar stimulatory effect of alpha-actinin on PC2 was also observed when hST vesicles were reconstituted in lipid bilayer. Thus, physical and functional interactions between PC2 and alpha-actinin may play an important role in abnormal cell adhesion, proliferation and migration observed in ADPKD.

A modified mammalian tandem affinity purification procedure to prepare functional polycystin-2 channel

The tandem affinity purification (TAP) procedure was initially developed as a tool for rapid purification of native protein complexes expressed at their natural levels in yeast cells. This purification procedure was also applied to study interactions between soluble proteins in mammalian cells. In order to apply this procedure to mammalian membrane proteins, we created a modified TAP tag expression vector and fused with the PKD2 gene, encoding a membrane cation channel protein, polycystin-2, mutated in 15% of autosomal dominant polycystic kidney disease. We generated epithelial Madin-Darby canine kidney cell line stably expressing TAP-tagged polycystin-2, improved the subsequent steps for membrane protein release and stability, and succeeded in purifying this protein. Using patch clamp electrophysiology, we detected specific polycystin-2 channel activities when the purified protein was reconstituted into a lipid bilayer system. Thus, this modified TAP procedure provides a powerful alternative to functionally characterize membrane proteins, such as ion channels, transporters and receptors, using cell-free system derived from mammalian cells.

Troponin I binds polycystin-L and inhibits its calcium-induced channel activation

Polycystin-L (PCL) is an isoform of polycystin-2, the product of the second gene associated with autosomal dominant polycystic kidney disease, and functions as a Ca(2+)-regulated nonselective cation channel. We recently demonstrated that polycystin-2 interacts with troponin I, an important regulatory component of the actin microfilament complex in striated muscle cells and an angiogenesis inhibitor. In this study, using the two-microelectrode voltage-clamp technique and Xenopus oocyte expression system, we showed that the calcium-induced PCL channel activation is substantially inhibited by the skeletal and cardiac troponin I (60% and 31% reduction, respectively). Reciprocal co-immunoprecipitation experiments demonstrated that PCL physically associates with the skeletal and cardiac troponin I isoforms in overexpressed Xenopus oocytes and mouse fibroblast NIH 3T3 cells. Furthermore, both native PCL and cardiac troponin I were present in human heart tissues where they indeed associate with each other. GST pull-down and microtiter binding assays showed that the C-terminus of PCL interacts with the troponin I proteins. The yeast two-hybrid assay further verified this interaction and defined the corresponding interacting domains of the PCL C-terminus and troponin I. Taken together, this study suggests that troponin I acts as a regulatory subunit of the PCL channel complex and provides the first direct evidence that PCL is associated with the actin cytoskeleton through troponin I.

Polycystin-2 interacts with troponin I, an angiogenesis inhibitor

Polycystin-2 (PC2), encoded by the PKD2 gene, is mutated in 10-15% of autosomal dominant polycystic kidney disease (ADPKD) patients. PC2 is a Ca(2+)-permeable nonselective cation channel and is present in kidney and many other organs. Likewise, PKD2-mutated patients and mice exhibit extrarenal abnormalities. In comparison with cysts in the kidney, liver, and pancreas, abnormalities in the heart, brain, and vascular vessels are less understood. In particular, roles of PC2 in muscle and endothelia remain largely unknown. In the present study, using a yeast two-hybrid screening, we discovered that the PC2 carboxyl terminal domain (D682-V968) interacts with the cardiac troponin I, an important regulatory component of the actin microfilament in cardiac muscle cells. This interaction was demonstrated by GST pull-down and microtiter binding assays. Dose-dependent binding between PC2 and troponin I followed a Michaelis-Menten relationship, indicating a 1:1 binding stoichiometry. The interacting domains were located to the R872-H927 segment of PC2 and the M1-V107 and K106-L158 segments of troponin I. Co-immunoprecipitation experiments demonstrated that the cardiac and two skeletal isoforms of troponin I were all associated with PC2, when coexpressed in mouse fibroblast NIH 3T3 cells and Xenopus oocytes. Furthermore, reciprocal co-immunoprecipitation verified the interaction between the native polycystin-2 and troponin I in human adult heart tissues. This study thus provides new evidence for a direct attachment of PC2 to the actin microfilament network, in addition to the recently identified association between PC2 and trypomyosin-1. Troponin I functions as an inhibitory subunit of the troponin complex for calcium-dependent regulation of muscle contraction and as an inhibitor of angiogenesis seen in ADPKD. It is possible that altered interaction due to pathogenic polycystin-1 or -2 mutations can account for angiogenesis in ADPKD and may be corrected to some extent by exogenous troponin I.

Climate change record in subsurface temperatures: A global perspective

Analyses of underground temperature measurements from 358 boreholes in eastern North America, central Europe, southern Africa, and Australia indicate that, in the 20th century, the average surface temperature of Earth has increased by about 0.5 degreesC and that the 20th century has been the warmest of the past five centuries. The subsurface temperatures also indicate that Earth's mean surface temperature has increased by about 1.0 degreesC over the past five centuries. The geothermal data offer an independent confirmation of the unusual character of 20th-century climate that has emerged from recent multiproxy studies.

The effect of triiodothyronine on the association of the rat apolipoprotein A-I, C-III and A-IV genes with the nuclear matrix

The association of apolipoprotein genes with the nuclear matrix of rat liver has been studied. The proportion of the apolipoprotein (apo) A-I, A-IV, C-III and E genes and the albumin gene associated with the matrix in normal rat liver was approximately 11%. In hypothyroid rats, the association of the apo A-I and apo A-IV genes with the matrix was reduced to 1.3% and 2.1% respectively, while in hyperthyroid rats, the association increased to 59% and 39% respectively. In contrast, the association of the apo C-III gene, which is located between the A-I and A-IV genes on chromosome 11, was not significantly affected by thyroid status. The association of the apo E and albumin genes with the matrix was also unaltered by changes in thyroid status. The increased association of the apo A-I and A-IV genes with the nuclear matrix of hyperthyroid animals accompanies the transcriptional activation of these genes by thyroid hormones.

Controlled release effect of insecticide microcapsules and their results in common household insect pest control

Since 1978 we have prepared microencapsulated insecticides by complex coacervation and interfacial polymerization for household insect pest control, fenthion being the main core element. A series of tests have been conducted against mosquitoes (Culex pipiens quinquefasciatus), cockroaches (Periplaneta americana) and bedbugs (Cimex lectularius), and the results indicate that microencapsulation can prolong persistent effects by 2-12 times, enhance safety and subdue offensive odour. Furthermore, the production cost is comparatively low.

Number and activity of active ribosomes in bacterial polyribosomes

Polyribosomes were isolated from Baccillus licheniformis, grown at 37 and 46 degrees C, and from Bacillus stearothermophilus, grown at 46 and 55 degrees C. The polyribosomes were incubated with either [3H]puromycin or [14C]phenylalanine. The number of active ribosomes (i.e. those to which growing polypeptide chains are attached) was calculated from the amount of [3H]peptidyl-puromycin formed. The activity of an active ribosome (i.e. the total number of amino acid molecules incorporated/unit time per active ribosome) was calculated from the uptake of [14C]phenylalanine. The number of active ribosomes per migrogram of RNA was as follows: for B. licheniformis, 1.66 X 10(12) and 1.72 X 10(12) at 37 and 46 degrees C respectively; for B. stearothermophilus, 2.59 X 10(12) at 46 and 55 degreesC respectively. The activity per active ribosome was as follows: for B. licheniformis, 0.61 and 0.05 at 37 and 46 degrees C respectively; for B. stearothermophilus, 0.58 and 0.42 at 46 and 55 degrees C respectively.

Fatty acid distribution in mesophilic and thermophilic strains of the genus Bacillus

The fatty acid distribution of three mesophilic and three thermophilic strains of the genus Bacillus was determined by gas chromatography of the fatty acid methyl esters. Fatty acid i-15:0 was the most abundant in both the mesophiles (51%) and the thermophiles (41%). The second most abundant fatty acid was a-15:0 in the mesophiles (22%), and i-17:0 in the thermophiles (27%). The fatty acid pair i-15:0, i-17:0 was the most predominant pair in both the mesophiles (61%) and the thermophiles (66%). The fatty acid pair a-15:0, a-17:0 was the second most predominant pair and was much higher in the mesophiles (30%) than in the thermophiles (15%). The average fatty acid chain length was 15.5 for the mesophiles and 16.0 for the thermophiles. The significance of these results for the lipid theory of thermophily is discussed.