Cryo-electron microscopy of vitrified specimens

Cryo-electron microscopy of vitrified specimens was just emerging as a practical method when Richard Henderson proposed that we should teach an EMBO course on the new technique. The request seemed to come too early because at that moment the method looked more like a laboratory game than a useful tool. However, during the months which ellapsed before the start of the course, several of the major difficulties associated with electron microscopy of vitrified specimens found surprisingly elegant solutions or simply became non-existent. The course could therefore take place under favourable circumstances in the summer of 1983. It was repeated the following years and cryo-electron microscopy spread rapidly. Since that time, water, which was once the arch enemy of all electronmicroscopists, became what it always was in nature – an integral part of biological matter and a beautiful substance.

Electron microscopy of frozen hydrated sections of vitreous ice and vitrified biological samples

The preparation and high resolution observation of frozen hydrated thin sections has been studied by transmission electron microscopy (TEM and STEM) on model systems, including pure water, protein solutions, catalase crystals, myelin sheath and various tissues. The state of the ice is determined by electron diffraction. Mass measurement in the electron microscope is used to determine section thickness and control hydration. An adequate depth of vitrified material for sectioning can be obtained from many biological suspensions or untreated tissues. Frozen hydrated sections around 100 nm thick can be produced under optimal conditions from vitreous ice or from vitrified biological samples. Sectioning, transfer and observation in the electron microscope is feasible without alteration of the sample hydration or its initial vitrification. Biological structures can be preserved and observed down to 10 nm. Under favourable working conditions, specimen compression during sectioning and electron beam damage are the factors limiting high resolution observations.

Synthesis and cytotoxicity of 1,6,7,8-substituted 2-(4'-substituted phenyl)-4-quinolones and related compounds: identification as antimitotic agents interacting with tubulin

A series of 1,6,7,8-substituted 2-(4'-substituted phenyl)-4-quinolones and related compounds have been synthesized and evaluated as cytotoxic compounds and as antimitotic agents interacting with tubulin. The 2-phenyl-4-quinolones (22-30) with substituents (e.g. F, Cl, and OCH3) at C-6, C-7, and C-8 show, in general, potent cytotoxicity against human lung carcinoma (A-549), ileocecal carcinoma (HCT-8), melanoma (RPMI-7951), and epidermoid carcinoma of the nasopharynx (KB) and two murine leukemia lines (P-388 and L1210). Introduction of alkyl groups at N-1 or C-4 oxygen led to inactive compounds (35-43 and 50). In addition, compounds 24, 26, and 27 were evaluated in the National Cancer Institute's 60 human tumor cell line in vitro screen. These compounds demonstrated the most marked effects in the screen on two colon carcinoma cell lines (COLO-205 and KM-20L2) and on a central nervous system tumor cell line (SF-539) with compound 26 the most potent of the three agents. Compounds 24, 26, and 27 were potent inhibitors of tubulin polymerization, with activity nearly comparable to that of the potent antimitotic natural products colchicine, podophyllotoxin, and combretastatin A-4. The three agents also inhibited the binding of radiolabeled colchicine to tubulin, but this inhibition was less potent than that obtained with the natural products.

Displacement limits for spatial frequency filtered random-dot cinematograms in apparent motion

Two-dimensional band-pass filtered random-dot cinematograms were used to study apparent movement mediated by the short-range process. In the first experiment maximum displacement (dmax) for correct direction of movement was measured for symmetrically filtered low-pass, medium-pass, and high-pass images. dmax was found to be limited by the grain size in the image and increased with the target area. Since eccentric presentation had no effect on dmax, the increase of dmax with target area suggests that apparent movement perception is a global process. In the second experiment the stimulus was filtered differentially in the two orthogonal directions using cone filtering. dmax was found to be commensurate with the length of the clusters in the direction of the movement.

Displacement of hepatitis B virus by hepatitis C virus as the cause of continuing chronic hepatitis

BACKGROUND/AIMS

It has been shown that hepatitis C virus (HCV) superinfection may suppress hepatitis B virus (HBV) leading to hepatitis B surface antigen (HBsAg) clearance and that hepatitis may persist after HBsAg clearance in a few patients. The role of HCV in continuing hepatitis after termination of chronic HBsAg antigenemia remains to be explored in a series of patients.

METHODS

HCV markers were studied using second generation enzyme immunoassay and polymerase chain reaction with reverse transcription and were compared between 41 patients with persistent alanine aminotransferase (ALT) elevation (hepatitis group) and 82 age/sex-matched patients with normal ALT (control group) after HBsAg clearance.

RESULTS

Twenty-six (63%) of the 41 hepatitis group patients were seropositive for antibodies to HCV (anti-HCV) compared with only 4 (5%) of 82 controls (P < 0.0001). Six patients of the hepatitis group and 1 control had an episode of acute hepatitis C with seroconversion of anti-HCV 1-68 months before HBsAg clearance. Of those seropositive for anti-HCV, serum HBV DNA was not detectable, and serum HCV RNA was detected in 23 (88.5%) of the 26 hepatitis patients but none of the 4 controls (P < 0.001). Liver biopsy in 6 anti-HCV positive patients with continuing hepatitis showed features compatible with chronic hepatitis C. HCV RNA, but not HBV DNA, was detected in liver tissues of these 6 patients.

CONCLUSIONS

The results suggest that HCV may usurp the role of HBV in chronic hepatitis and act as the major cause of continuing hepatitis or ALT elevation after HBV/HBsAg clearance.

Cooperative phenomena in apparent movement perception of random-dot cinematograms

To determine if apparent movement perception of random-dot cinematograms (RDC) is a cooperative process, we examined the interaction between adjacent areas whose movement, when perceived independently, was in opposite directions. The stimulus contained alternating ambiguous and unambiguous horizontal random-dot stripes of equal width. The ambiguous areas were biased in a specific direction opposite to the movement of the unambiguous areas. The cooperative process was evaluated by noting that the unambiguous areas were able to reverse the perceived direction of the ambiguous areas. Thus all dots were seen to move uniformly in the unambiguous direction. This phenomenon was dependent on the amount of bias inserted in the ambiguous areas and the width of the stripes. A Cooperative Strength (CS) index was computed. We found that CS depended on the stripe width, and that the average cooperative neighborhood was about 15 min arc in visual angle, suggesting a relationship to the diameter of cortical hypercolumns.

Amino acid sequence of mouse submaxillary gland renin

The complete amino acid sequences of the heavy chain and light chain of mouse submaxillary gland renin have been determined. The heavy chain consists of 288 amino acid residues having a Mr of 31,036 calculated from the sequence. The light chain contains 48 amino acid residues with a Mr of 5,458. The sequence of the heavy chain was determined by automated Edman degradations of the cyanogen bromide peptides and tryptic peptides generated after citraconylation, as well as other peptides generated therefrom. The sequence of the light chain was derived from sequence analyses of the peptides generated by cyanogen bromide cleavage or by digestion with Staphylococcus aureus protease. The sequences in the active site regions in renin containing two catalytically essential aspartyl residues 32 and 215 were found identical with those in pepsin, chymosin, and penicillopepsin. Comparison of the amino acid sequence of renin with that of porcine pepsin indicated a 42% sequence identity of the heavy chain with the amino-terminal and middle regions and a 46% identity of the light chain with the carboxyl-terminal region of the porcine pepsin sequence. Residues identical in renin and pepsin are distributed throughout the length of the molecules, suggesting a similarity in their overall structures.

Inversion of articulatory-to-acoustic transformation in the vocal tract by a computer-sorting technique

We present numerical methods for studying the relationship between the shape of the vocal tract and its acoustic output. For a stationary vocal tract, the articulatory-acoustic relationship can be represented as a multidimensional function of a multidimensional argument: y=f(x), where x, y are vectors describing the vocal-tract shape and the resulting acoustic output, respectively. Assuming that y may be computed for any x, we develop a procedure for inverting f(x). Inversion by computer sorting consists of computing y for many values of x and sorting the resulting (y,x) pairs into a convenient order according to y; x for a given y is then obtained by looking up y in the sorted data. Application of this method for determining parameters of an articulatory model corresponding to a given set of formant frequencies is presented. A method is also described for finding articulatory regions (fibers) which map into a single point in the acoustic space. The local nature of f(x) is determined by linearization in a small neighborhood. Larger regions are explored by extending the linear neighborhoods in small steps. This method was applied for the study of compensatory articulation. Sounds produced by various articulations along a fiber were synthesized and were compared by informal listening tests. These tests show that, in many cases of interest, a given sound could be produced by many different vocal-tract shapes.

Antitumor agents, 138. Rotenoids and isoflavones as cytotoxic constitutents from Amorpha fruticosa

Eight cytotoxic compounds have been isolated from the CHCl3 extract of Amorpha fruticosa. One compound, 6'-O-D-beta-glucopyranosyldalpanol [10], is a new cytotoxic rotenoid. Another known rotenoid, 12 alpha beta-hydroxyamorphigenin [6], was first shown to exhibit extremely potent cytotoxicity (ED50 < 0.001 microgram/ml) in six neoplastic cell lines. In addition to these compounds, three isoflavones (afrormosin [1], 7,2',4', 5'-tetramethoxyisoflavone [2], 8-methylretusin [3]) and five rotenoids (amorphispironone [4], amorphigenin [5], dalpanol [7], 12a beta-hydroxydalpanol [8], and tephrosin [9]) were isolated. Compound 8 was isolated for the first time as a natural product from this plant. The structures of these compounds were established on the basis of spectral data; some were further confirmed by X-ray crystallographic analysis.

Diagnostic Accuracy of Transcranial Doppler for Brain Death Confirmation: Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Transcranial Doppler is a useful ancillary test for brain death confirmation because it is safe, noninvasive, and done at the bedside. Transcranial Doppler confirms brain death by evaluating cerebral circulatory arrest. Case series studies have generally reported good correlations between transcranial Doppler confirmation of cerebral circulatory arrest and clinical confirmation of brain death. The purpose of this study is to evaluate the utility of transcranial Doppler as an ancillary test in brain death confirmation.

MATERIALS AND METHODS

We conducted a systematic review of the literature and a diagnostic test accuracy meta-analysis to compare the sensitivity and specificity of transcranial Doppler confirmation of cerebral circulatory arrest, by using clinical confirmation of brain death as the criterion standard.

RESULTS

We identified 22 eligible studies (1671 patients total), dating from 1987 to 2014. Pooled sensitivity and specificity estimates from 12 study protocols that reported data for the calculation of both values were 0.90 (95% CI, 0.87-0.92) and 0.98 (95% CI, 0.96-0.99), respectively. Between-study differences in the diagnostic performance of transcranial Doppler were found for both sensitivity (I(2) = 76%; P < .001) and specificity (I(2) = 74.3%; P < .001). The threshold effect was not significant (Spearman r = -0.173; P = .612). The area under the curve with the corresponding standard error (SE) was 0.964 ± 0.018, while index Q test ± SE was estimated at 0.910 ± 0.028.

CONCLUSIONS

The results of this meta-analysis suggest that transcranial Doppler is a highly accurate ancillary test for brain death confirmation. However, transcranial Doppler evaluates cerebral circulatory arrest rather than brain stem function, and this limitation needs to be taken into account when interpreting the results of this meta-analysis.

Displacement limits, directional anisotropy and direction versus form discrimination in random-dot cinematograms

Apparent motion mediated by the short-range process was studied. Random-dot cinematograms were used to determine the maximum displacement (dmax) for motion-direction and pattern discrimination. dmax is the maximum spatial separation between a correlated region (target) in the two successively presented random-dot images, when observers can correctly identify the direction of motion or the shape of the target. We have found that: (1) dmax for motion-direction discrimination increases with the square root of the display area; (2) dmax is invariant with eccentricities of 4 deg arc; (3) For rectangular targets and brief presentations, dmax increases with increases of that target-dimension which is parallel to the orientation of the movement. These findings indicate that short-range movement perception is an orientation specific global process. Furthermore, motion-direction discrimination and pattern discrimination of random-dot cinematograms may be mediated by different levels of processes. However, even for pattern discrimination dmax in visual angle increases with increased target area.

Prospective evaluation of systematic sextant transition zone biopsies in large prostates for cancer detection

OBJECTIVES

A prospective evaluation was performed to define the role of systematic transition zone (TZ) biopsies in prostates larger than 50 cc.

METHODS

From August 1994 to July 1997, 213 consecutive patients referred because of an abnormal digital rectal examination or prostate-specific antigen greater than 4.0 ng/mL had a calculated prostate size greater than 50 cc by transrectal ultrasound (TRUS) measurement. These patients underwent TRUS-guided sextant biopsies of the peripheral zone (PZ) and TZ.

RESULTS

The median calculated prostate size was 70 cc with a TZ size of 39 cc. Fifty-five cases of carcinoma of the prostate were found, giving a 26% detection rate. The TZ biopsies detected cancer in 30 of the 55 patients (55% sensitivity) compared with the 47 patients detected by the PZ biopsies (85% sensitivity). Seven cancers (13%) were detected only by the additional TZ biopsies. TZ biopsies revealed bilateral tumors when the PZ biopsies had shown unilateral disease in 2 cases. In 6 cases the TZ biopsies showed higher Gleason grade tumors than was found in the PZ. In the 30 cases with positive TZ biopsy, concordance between the PZ and TZ biopsies occurred in 74% (133 of 180) of the sectors. The PZ biopsy detected cancer in 43 of 66 corresponding sectors that had positive TZ biopsies, giving a sensitivity of 65% and a negative predictive value of 80%.

CONCLUSIONS

Routine PZ biopsies missed detecting 13% of the cancers found with the addition of sextant TZ biopsies in patients with large prostates (greater than 50 cc). In addition, 14% of the patients with cancer had upgrading or detection of bilateral tumor with the added biopsies. Routine systematic sextant TZ biopsies should be considered in patients with prostates greater than 50 cc in size.

Feeding motor program in Limax. I. Neuromuscular correlates and control by chemosensory input

The feeding motor program(FMP) of the terrestrial slug Limax maximus was examined in vivo and in vitro. The feeding pattern of intact animals shows an initial increase in bite frequency followed by a plateau phase. Recordings obtained from semi-intact preparations of the lips, brain, and buccal mass established the correlation of activity in buccal ganglion nerve roots with the protraction-retraction bite cycle. A preparation of the lips, cerebral ganglia, and buccal ganglia was developed, such that, repetitive chemostimulation of the lips yields reproducible bouts of FMP. Sources of proprioceptive feedback from buccal muscles were demonstrated. The feasibility of computer scoring of the FMP is documented. The results demonstrate that aspects of in vivo feeding behavior are retained and identifiable in highly dissected, in vivo preparations.

Isolation and activation of inactive renin from human kidney and plasma. Plasma and renal inactive renins have different molecular weights

Inactive renin and active renin from human kidney and human plasma were prepared in highly purified forms by three steps of chromatography on Octyl-Sepharose, immunoaffinity chromatography, and pepstatin-amino hexyl Sepharose CL-4B. The inactive renin and active renin from human kidney had molecular weights of 51,000 and 44,000 as measured by a calibrated gel filtration column run with internal molecular weight standards. Molecular weights of plasma inactive renin and active renin were 56,000 and 51,000 respectively. Both inactive and active renins were found to be heterogeneous, consisting of several components with different isoelectric points. Renal inactive renin has higher pI values of 6.40, 6.10, 5.90, 5.61, and 5.40. Renal active renin has pI values of 5.73, 5.40, 5.25, and 5.13. The pI values of plasma inactive renin were 6.37, 6.08, 5.77, 5.36, and 5.25; of plasma active renin, 5.68, 5.40, 5.33, and 5.25. Trypsin activation and plasmin activation of plasma inactive renin produced an active enzyme with similar molecular weight but lower pI values. Acid activation of inactive renin did not change the molecular weight and pI values.

Rapid taste-aversion learning by an isolated molluscan central nervous system

The isolated lips and nervous system of the terrestrial slug Limax maximus will produce some of the feeding behavior of the intact animal; i.e., they generate the rhythmic neural activity characteristic of ingestion in response to food extracts applied to the lips. This preparation will respond to a variety of food extracts that elicit feeding in the whole animal. This provides the opportunity for aversive conditioning experiments involving taste discrimination. Pairing lip chemostimulation by attractive food extracts with lip chemostimulation by using bitte plant secondary substances can cause the isolatd brain to selectively suppress its neural response to one food extract while remaining responsive to another. Such isolated brains can learn after one or two trials and retain the learning for more than 8 hr.

Generation of dark-bright soliton trains in superfluid-superfluid counterflow

The dynamics of two penetrating superfluids exhibit an intriguing variety of nonlinear effects. Using two distinguishable components of a Bose-Einstein condensate, we investigate the counterflow of two superfluids in a narrow channel. We present the first experimental observation of trains of dark-bright solitons generated by the counterflow. Our observations are theoretically interpreted by three-dimensional numerical simulations for the coupled Gross-Pitaevskii equations and the analysis of a jump in the two relatively flowing components' densities. Counterflow-induced modulational instability for this miscible system is identified as the central process in the dynamics.

Differential leukocyte counts on admission predict outcomes in patients with acute ischaemic stroke treated with intravenous thrombolysis

BACKGROUND AND PURPOSE

To determine the association of differential leukocyte counts on admission with efficacy and safety outcomes in patients with acute ischaemic stroke (AIS) treated with intravenous thrombolysis (IVT).

METHODS

Consecutive patients with AIS receiving IVT were evaluated at two stroke centers. Differential leukocyte counts and neutrophil:lymphocyte ratio (NLR) were determined during the initial 12 h of admission. Efficacy outcomes were favorable functional outcome (FFO) (modified Rankin Scale scores of 0-1) and functional independence (FI) (modified Rankin Scale scores of 0-2) at 3 months, whereas safety outcomes were symptomatic intracranial hemorrhage and 3-month mortality.

RESULTS

Among 657 IVT-treated patients with AIS, the mean age was 64 ± 14 years, 50% were female and median National Institutes of Health Stroke Scale score was 7 points (interquartile range, 4-13). Lower neutrophil and leukocyte counts and NLR counts were observed in patients with 3-month FFO and FI, whereas higher counts were observed in patients who died at 3 months. The best discriminative factors for 3-month FFO and FI were NLR < 2.2 (sensitivity 51.4%, specificity 63.1%) and leukocyte count <8100/μL (sensitivity 57.5%, specificity 55.1%), respectively. After adjustment for potential confounders, NLR < 2.2 was associated with higher odds of FFO [odds ratio (OR), 1.56; 95% confidence interval (CI), 1.08-2.24; P = 0.018], whereas leukocyte count <8100/μL demonstrated higher odds of 3-month FI (OR, 1.69; 95% CI, 1.11-2.57; P = 0.014) and lower odds of 3-month mortality (OR, 0.31; 95% CI, 0.16-0.60; P = 0.001). Combined neutrophil (<6800/μL) and leukocyte (<8100/μL) counts demonstrated a strong interaction for 3-month FI (OR, 1.73; 95% CI, 1.13-2.67; P interaction = 0.012).

CONCLUSIONS

Differential leukocyte counts on admission were independently associated with clinical outcomes in patients with AIS treated with IVT. These inflammatory biomarkers are potential targets for adjunctive neuroprotection in this stroke subgroup.

Minocycline and matrix metalloproteinase inhibition in acute intracerebral hemorrhage: a pilot study

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) is a devastating cerebrovascular disorder with high morbidity and mortality. Minocycline is a matrix metalloproteinase-9 (MMP-9) inhibitor that may attenuate secondary mechanisms of injury in ICH. The feasibility and safety of minocycline in ICH patients were evaluated in a pilot, double-blinded, placebo-controlled randomized clinical trial.

METHODS

Patients with acute onset (<12 h from symptom onset) ICH and small initial hematoma volume (<30 ml) were randomized to high-dose (10 mg/kg) intravenous minocycline or placebo. The outcome events included adverse events, change in serial National Institutes of Health Stroke Scale score assessments, hematoma volume and MMP-9 measurements, 3-month functional outcome (modified Rankin score) and mortality.

RESULTS

A total of 20 patients were randomized to minocycline (n = 10) or placebo (n = 10). The two groups did not differ in terms of baseline characteristics. No serious adverse events or complications were noted with minocycline infusion. The two groups did not differ in any of the clinical and radiological outcomes. Day 5 serum MMP-9 levels tended to be lower in the minocycline group (372 ± 216 ng/ml vs. 472 ± 235 ng/ml; P = 0.052). Multiple linear regression analysis showed that minocycline was associated with a 217.65 (95% confidence interval -425.21 to -10.10, P = 0.041) decrease in MMP-9 levels between days 1 and 5.

CONCLUSIONS

High-dose intravenous minocycline can be safely administered to patients with ICH. Larger randomized clinical trials evaluating the efficacy of minocycline and MMP-9 inhibition in ICH patients are required.