Expression patterns of TEL genes in Poaceae suggest a conserved association with cell differentiation

Poaceae species present a conserved distichous phyllotaxy (leaf position along the stem) and share common properties with respect to leaf initiation. The goal of this work was to determine if these common traits imply common genes. Therefore, homologues of the maize TERMINAL EAR1 gene in Poaceae were studied. This gene encodes an RNA-binding motif (RRM) protein, that is suggested to regulate leaf initiation. Using degenerate primers, one unique tel (terminal ear1-like) gene from seven Poaceae members, covering almost all the phylogenetic tree of the family, was identified by PCR. These genes present a very high degree of similarity, a much conserved exon-intron structure, and the three RRMs and TEL characteristic motifs. The evolution of tel sequences in Poaceae strongly correlates with the known phylogenetic tree of this family. RT-PCR gene expression analyses show conserved tel expression in the shoot apex in all species, suggesting functional orthology between these genes. In addition, in situ hybridization experiments with specific antisense probes show tel transcript accumulation in all differentiating cells of the leaf, from the recruitment of leaf founder cells to leaf margins cells. Tel expression is not restricted to initiating leaves as it is also found in pro-vascular tissues, root meristems, and immature inflorescences. Therefore, these results suggest that TEL is not only associated with leaf initiation but more generally with cell differentiation in Poaceae.

Responses to whole head-and-body tilts with and without passive ankle dorsiflexion in the absence of visual feedback

OBJECTIVES

We have investigated lower limb responses in seven blindfolded healthy subjects to well controlled tilts in the standing position. Our aims were (1) to determine the effect of head acceleration magnitude on responses evoked by whole head-and-body tilts, and (2) to establish whether tilt-evoked responses are modifiable by passive ankle dorsiflexion. Whole head-and-body tilts evoked responses in the biceps femoris, medial gastrocnemius and tibialis anterior muscles.

METHODS

Seven young healthy subjects stood on a spring-activated tilting apparatus and underwent sudden whole head-and-body tilts of about 15 degrees from the vertical position, with or without passive ankle dorsiflexion. Head acceleration was recorded with a linear accelerometer and ankle angular displacement with a potentiometer. Surface EMG signals were recorded in the right biceps femoris, medial gastrocnemius and tibialis anterior muscles.

RESULTS

As the peak of head acceleration was increased from 0.5 g to 1.8 g, the frequency of occurrence of tilt-evoked responses increased from 7% to 60% of trials in the biceps femoris muscle during whole head-and-body tilts. In general, the more proximal muscle (biceps femoris) was activated before the more distal muscle (medial gastrocnemius) during whole head-and-body tilts, while the opposite pattern was found during tilt with dorsiflexion.

CONCLUSIONS

Our results indicate that the occurrence of tilt-evoked responses increases with an increase in the amplitude of tilting acceleration. This suggests that tilt-evoked responses are dependent, at least in part, on vestibular stimulation. In addition, the spatio-temporal pattern of biceps femoris and medial gastrocnemius muscle activation was opposite during whole head-and-body tilts and tilts with dorsiflexion. This finding suggests that foot/ankle somatosensory inputs can modify tilt-evoked responses.

A postural adaptation test for stroke patients

PURPOSE

To explore the interrater reliability of the Advanced Mobility and Balance Scale (AMBS) and to determine its discriminative capacity in stroke patients.

METHODS

Twelve hemiparetic patients and six healthy elderly volunteers were videotaped while: (1) executing rapid head motions during standing and walking; and (2) standing and walking on a slope. Five physical therapists viewed the videotapes to establish interrater reliability.

RESULTS

Interrater reliability: Intraclass correlation ratios ranged from 0.93-0.97 for the AMBS global as well as slope and head turn subscores. Construct validity: One-way ANOVAs and post-hoc pairwise comparisons were performed to determine whether there was a difference in scores between high (HFL) and low functional-level (LFL) stroke patients (based on gait speed) and healthy subjects. Mean (+/-SD) global scores were 45 +/- 3 for healthy subjects, 40 +/- 9 for HFL stroke patients and 25 +/- 1 for LFL stroke patients (p < 0.05 for HFL versus LFL patients and LFL patients versus healthy subjects). The AMBS slope subscores were 22 +/- 2, 19 +/- 5, 9 +/- 7 for healthy, HFL and LFL subjects respectively (p < 0.05 for HFL versus LFL patients and LFL patients versus healthy subjects).

CONCLUSION

The AMBS has excellent interrater reliability and good discriminative capacities.

Rhythmical eye-head-torso rotation alters fore-aft head stabilization during treadmill locomotion in humans

A repetitive manoeuvre called torso rotation (TR) is known to temporarily reduce the gain of the horizontal vestibulo-ocular reflex by 10-15% in healthy humans. TR consists of a series of rhythmical rotations of the eyes, head and upper body executed continuously for 30 minutes while standing. Our aim was to investigate whether TR affects the ability to hold the head in a fixed fore-aft position relative to space while walking on a treadmill with eyes closed. Ten healthy subjects stood in a carefully standardized position on a stationary treadmill. The treadmill started unexpectedly and ran for 4 s at 29 cm/s. The test stimulus was a linear acceleration in the fore-aft direction at the moment of treadmill start-up. Linear head position (i.e., ability to stabilize the head) was measured during and following the stimulus. A mechanical system prevented head rotation. Two series of 60 trials were performed before TR (control 1 and control 2 series) and one after TR. Before TR, subjects drifted rearward at an average drift velocity +/- S.D. = 3.1 +/- 0.9 cm/s. This drift was reasonably stable over time within and between the two control series. After TR, head holding ability was further impaired, with subjects having more difficulty to stabilize their head after treadmill start-up. In the first 10 trials after the arrest of TR, the average drift velocity was significantly larger than before TR(6.1 +/- 1.5 cm/sec, p < 0.01). Recovery to control values followed a roughly exponential time course, with 67% recovery occurring in the first 3.4 minutes after TR. Our results indicate that TR impairs the ability to sense and/or respond to fore-aft linear accelerations of the head following treadmill start-up in the absence of vision.

Reflex Interactions during Whole Head-and-Body Tilts are Modified by Age in Humans

We have demonstrated that lower limb extensor muscle response to tibial nerve stimulation is significantly facilitated by whole head-and-body tilt in the forward direction. Our aim was to examine whether this reflex interaction is influenced by age. Reflexes were elicited in lower limb muscles by electrical stimulation (ES) of the right tibial nerve. We compared reflexes during supported stance (ESalone) and sudden forward tilting of the whole head-and-body (Tilt+ES) between 10 healthy subjects aged 66 ± 4 years and 13 subjects aged 27 ± 3 years. In young subjects the area of response evoked in the ipsilateral vastus lateralis (iVL) was significantly increased by 74% during Tilt+ES as compared with ESalone (p < 0.05). Moreover, the latency of contralateral VL and soleus muscle responses (cVL and/or cSO) was significantly shorter by 61 ms during Tilt+ES than ESalone (p < 0.01). In contrast, older subjects showed no significant increase in the excitability of iVL muscle response and cVL and/or cSO muscle responses during Tilt+ES as compared with ESalone despite the application of similar intensity of ES and head acceleration as in young subjects. Our findings showed that the interaction between ES-evoked and tilt-evoked responses in lower limb extensor muscles is modified with age, which suggests modifications of sensorimotor integration involved in balance control.

Human soleus H-reflex excitability is decreased by dynamic head-and-body tilts

The modulation of soleus (SO) H-reflex excitability during dynamic whole head-and-body tilts (WHBT) was investigated in normal healthy subjects. Between 30 and 70 ms, and 151 and 190 ms after head acceleration onset, the H-reflex amplitude was smaller than during quiet standing by 7.6% (p < 0.01) and 15.4% (p = 0.06) respectively. This finding suggested that dynamic WHBT reduced the excitability of the predominantly monosynaptic stretch reflex are in the majority of the subjects studied.

Responses to dynamic head-and-body tilts are enhanced in Parkinson's disease

BACKGROUND

Previous studies demonstrated that destabilizing responses to slow perturbations were enhanced in patients with Parkinson's disease (PD). Our objectives were to investigate the influence of PD on responses to faster whole head-and-body tilts in the standing position, and to establish whether any modification of tilt-evoked responses in PD patients was related to possible changes in the modulation of soleus (SO) H-reflex.

METHODS

Ten PD patients and 10 age-matched normal subjects assumed a standing position on an L-shaped tilting apparatus. Their head and shoulders were firmly attached to the back support of the apparatus, while their feet were fixated to the standing platform. With their vision occluded, the subjects's whole head-and-body was suddenly tilted forward to 20 degrees, at a peak head acceleration of 0.7 g +/- 0.1 g. Tilt-evoked responses were recorded from the lower limb muscles bilaterally. In addition, 40 H-reflexes were elicited in the SO muscle at 30-190 ms intervals after the onset of head acceleration. The M response amplitude was kept within +/- 15% of its control value.

RESULTS

PD patients demonstrated an abnormally high responsiveness to whole head-and-body tilts in comparison with age-matched normal subjects. This was shown by the significantly larger proportion of PD patients manifesting responses in the SO, biceps femoris and vastus lateralis muscles (p < 0.05), as well as their significantly larger SO response area (413%; p < 0.01). In contrast, the amplitude of the SO H-reflex was significantly increased by only 14% (p < 0.05) in these patients, and only at 30-70 ms after head acceleration onset.

CONCLUSIONS

The overexcitable tilt-evoked responses of PD patients could originate from a reduced ability to suppress responses when the body is supported. This enhanced excitability of tilt-evoked responses was probably not due to motoneuronal hyperexcitability or decreased presynaptic inhibition of the group Ia terminals involved in the mainly monosynaptic H-reflex pathway. Thus, we hypothesize that the control of spinal interneurons involved in the tilt-evoked responses may be defective in PD.

Extensor muscle responses to tibial nerve stimulation are enhanced during dynamic tilts in standing humans

We studied the interaction between muscle responses evoked in standing by electrical stimulation (ES) of the tibial nerve and dynamic tilts of the head-and-body in 13 young healthy subjects. Subjects were attached to an L-shaped tilting apparatus and underwent sudden forward tilting of their head-and-body as a whole, without ankle rotation. During such tilts, the area of response evoked in the ipsilateral vastus lateralis (iVL) muscle by the ES was significantly increased by 74% as compared to quiet supported stance (P = 0.01). The response latency of the contralateral VL and soleus muscles i.e. the crossed extension reflex, was significantly shorter during tilt (54 +/- 22 ms) than during quiet supported stance (115 +/- 13 ms, P < 0.01). The increased excitability of extensor muscles activated by ES during tilt seems appropriate to maintain stance during a forward perturbation of the body.

Functional modulation of the human flexion and crossed extension reflexes by body position

The effects of body position on the electrically evoked flexion (FR) and crossed extension reflexes (CER) were investigated in humans. The FR area in the ipsilateral tibialis anterior muscle was significantly smaller during sitting than supported stance by 36% (P < 0.01). In contrast, the excitability of extensor muscles on both sides was enhanced in standing. For instance, twice as many subjects manifested a response in the ipsilateral vastus lateralis (VL) and the contralateral VL and/or soleus muscles (i.e. the CER) in standing than sitting. The FR and CER modulation observed seems to be dictated by the difference in functional demand between sitting and supported stance.

False-positive 201thallium study in Wolff-Parkinson-White syndrome

Wolff-Parkinson-White syndrome (WPW) is known to cause abnormal rest electrocardiogram and stress tests. Consequently, the diagnosis of coronary artery disease (CAD) may be difficult in patients with WPW. Previous reports have described false positive stress 201thallium studies in WPW, but the absence of CAD has rarely been confirmed by coronary angiography. A case of false positive stress 201thallium scintigraphy confirmed by angiography is presented. Left ventricular contractile asynchrony can explain the defects observed in myocardial perfusion scintigraphy. The importance of the defects relates to the length of the delta wave.

cDNA cloning of a human 100 kDa de-ubiquitinating enzyme: the 100 kDa human de-ubiquitinase belongs to the ubiquitin C-terminal hydrolase family 2 (UCH2)

The full length cDNA encoding a 100 kDa human de-ubiquitinating enzyme, referred to as de-ubiquitinase was obtained using one clone selected from a randomly sequenced human brain cDNA library and specific primers. The sequence of 18 peptides generated from the de-ubiquitinase isolated from out-dated human erythrocytes matched perfectly with the predicted amino acid sequence, which would encode a protein containing 858 amino acids (calculated M(r) = 95,743 Da). Homology search disclosed that the protein is a member of a large family of ubiquitin C-terminal hydrolases (UCH2), that was defined on the basis of the presence of two specific patterns, 'the Cys- and His-domains', which are likely to be involved in the de-ubiquitinating activity [7]. An additional conserved region, 'the aspartic acid domain', was also identified, the functional role of which is unknown.

Structural characterization and expression of the human dehydroepiandrosterone sulfotransferase gene

Dehydroepiandrosterone sulfotransferase catalyzes the transformation of dehydroepiandrosterone to dehydroepiandrosterone sulfate, the most abundant steroid in circulation in the human and primate. Dehydroepiandrosterone sulfate serves as precursor for the formation of active androgens and estrogens in peripheral target tissues. In addition, blockade at the dehydroepiandrosterone level could give raise to high level of DHEA and thus disorders due to mild excess of androgen. Recently, the cDNA encoding dehydroepiandrosterone sulfotransferase has been isolated from a human liver cDNA library. To study the regulation and expression, as well as the possible defect linked to DHEA sulfotransferase gene, we have isolated and characterized its structure by screening a lambda EMBL3 library of human leukocyte genomic DNA using human dehydroepiandrosterone sulfotransferase cDNA as a probe. Sequencing of the gene shows that it is included in approximately 17 kb and contains six exons separated by five introns. Northern blot analysis shows a strong signal in the adrenals and liver, whereas no signal was detected in the spleen, thymus, prostate, testis, ovary, small intestine, colon, peripheral blood leukocytes, heart, brain, placenta, lung, skeletal muscle, kidney, or pancreas. Using primer extension analysis, the transcription start site is located at nucleotide 98 upstream from the ATG initiating codon. Putative TATA and CAAT boxes are situated at positions 72 and 96 upstream from the transcription start site, respectively. Using DNA from a panel of human/rodent somatic cell hybrids, and amplification of the gene by the polymerase chain reaction, the human dehydroepiandrosterone sulfotransferase gene has been assigned to chromosome 19.

A spring-activated tilting apparatus for the study of balance control in man

A tilting apparatus has been designed and constructed to produce fore-aft whole head-and-body tilt (WHBT) alone, or in combination with ankle dorsiflexion of standing subjects, about an axis colinear with the ankle joint. The apparatus is composed of a vertical tilting structure attached to a supporting base. Mechanical rotation of the vertical tilting structure is achieved by a spring activating system mounted on its base. Subjects are secured to the vertical structure by a body harness system with the head fixed, and the feet secured to the standing platform. Simultaneous dynamic WHBT and ankle joint displacement are induced by rotating the vertical support; whereas WHBT alone is achieved by concurrent rotation of both the vertical support and standing platform. Tilts are triggered manually, and data acquisition precedes head acceleration onset by 50-100 ms to provide suitable baseline values. This tilting apparatus has been successfully used to apply forward WHBT in 34 subjects with height ranging from 1.55 to 1.87 m and weights from 42 to 95 kg, and at magnitudes of peak head acceleration varying from 0.4 to 2.2 g as measured by a linear accelerometer mounted on a dental bite. These acceleration rates can be reproduced with minor variation in the same subjects. Moreover, the area under the head acceleration traces was reproducible within 15% between subjects. Tilts can be delivered with concomitant ankle dorsiflexion. These features make the low-cost tilting apparatus a very useful tool for the study of human tilting reactions in both laboratories and clinical settings.

A human de-ubiquitinating enzyme with both isopeptidase and peptidase activities in vitro

Some enzymatic and physicochemical properties of a human ubiquitin-specific isopeptidase are reported. The enzyme was purified to homogeneity from red blood cells and its specificity towards polymeric ubiquitin substrates suggests a de-ubiquitinating activity capable of cleaving 'head-to-tail' polyUb chains as well as isoamide 'branched' Ub dimers. KM values show a 10 fold preference for the cleavage of branched Ub dimers over head-to-tail Ub dimers. The enzymatic activity can be strongly inhibited by various peptides containing either of the cleavage site sequences found in Ub polymers, but not by unrelated peptides. The enzyme is monomeric under reducing conditions and exhibits a globular shape with an average diameter of 9 nm, an S20,w value of 5.2 S and a molar mass of 110 kDa +/- 10%. Because the enzyme cleaves both peptide-linked and isopeptide-linked Ub moieties from substrates, we propose to name it de-ubiquitinase rather than isopeptidase.

Two-dimensional polyacrylamide gel electrophoresis analysis of cryoglobulins and identification of an IgM-associated peptide

The clonality of immunoglobulins (Igs) in cryoprecipitates (n = 41) was studied by two-dimensional polyacrylamide gel electrophoresis (2-D PAGE). Our series included 24 cryoglobulins characterized by immunofixation electrophoresis (IF), 12 'trace amount' cryoglobulins, defined by a protein content in the precipitate of less than 0.05 mg/ml of serum, and five cryoglobulins of undetermined protein composition by IF. 2-D PAGE analysis showed polyclonal IgG associated either with monoclonal Igs (type II cryoglobulins; n = 14) or with polyclonal IgM (type III cryoglobulins; n = 14). In ten cryoprecipitates (two 'trace amount' cryoglobulins as well as seven of 19 type II and as one of five type III cryoglobulins by IF) polyclonal IgG were associated with a mixture of polyclonal and monoclonal IgM. These cryoglobulins were tentatively named type II-III cryoglobulins. A monoclonal IgM was observed in one cryoprecipitate (type I cryoglobulins). Two cryoglobulins presented unexpected 2-D patterns, characterized by the presence of oligoclonal IgM, with trace amounts of Igs of different isotypes (tentatively named type II-III(variant) cryoglobulins). A peptide of 44 kDa with a pI of 5.45 was observed in all cryoglobulins containing IgM (n = 40). This peptide was also present in purified monoclonal or polyclonal IgM fractions. N-terminal microsequencing (12 amino acid residues) revealed that this IgM-associated peptide was an unknown protein. Our results highlight the role of 2-D PAGE as an aid in the analysis of cryoglobulins.

Hip-spine movement interaction and muscle activation patterns during sagittal trunk movements in low back pain patients

Profiles of hip-spine movement interaction and muscle activations were characterized in 10 low back pain patients and in 10 normal subjects during trunk forward bending and extension. Electrogoniometric recordings showed that patients performed the movements significantly more slowly than normal subjects when asked to choose a comfortable cadence. For movements performed at the same velocity and amplitude, only the movement profiles at the spine and activation patterns of the erector spinae (ES) muscle during flexion were found to be significantly different between the two groups. A detailed analysis revealed that a subgroup of six patients (SG2) with an abnormal hip-spine movement interaction showed a significant (P < 0.01) lack of relaxation in ES muscle at the end of flexion. Patients from SG2 had pain for a longer time (P < 0.01) compared to patients from SG1 with normal movement and electromyographic profiles. Given the small sample size, these results are not conclusive, but they suggest that the lack of relaxation of the ES muscle may be associated with perturbation of movement patterns and the duration of the symptoms.

Micropreparative two-dimensional electrophoresis allowing the separation of samples containing milligram amounts of proteins

We describe some simple modifications to the micropreparative two-dimensional (2-D) electrophoresis procedure using immobilized pH gradients in the first dimension and sodium dodecyl sulfate-electrophoresis in the second dimension. The geometry of the immobilized pH gradient strips has been changed to allow the use of large sample application cups that can accommodate greater sample volumes. The use of narrow range immobilized pH gradients with a large sample loading volume allows an efficient resolubilization of polypeptides after the first dimension. As a result, the vertical streaking caused by too high a protein concentration is eliminated in the second dimension. Protein identification by N-terminal sequencing is facilitated by the large protein load (1-15 mg) which can be employed using this modification. Spots not normally detectable on conventional analytical 2-D maps, even with sensitive silver staining, are observed. Results for plasma and liver proteins are shown.

Human liver protein map: update 1993

This publication updates the reference human liver protein map. By microsequencing, 27 spots or 34 polypeptide chains were identified. The most abundant polypeptides detected on the silver stained liver map were key elements in major hepatic biochemical pathways. The new polypeptides and previously known proteins are listed in a table and/or labeled on the protein map, thus providing the 1993 reference human liver SWISS-2DPAGE database. SWISS-2DPAGE and the SWISS-PROT protein sequence databases are closely linked together through the use of common accession numbers.

Plasma and red blood cell protein maps: update 1993

This publication updates the reference plasma and red blood cell protein maps obtained with immobilized pH gradients. Seventeen polypeptide spots or chains were partially characterized by direct N-terminal sequencing or by sequencing of peptides obtained from enzymatic digestion. Additional new polypeptides and previously known proteins are listed in a table and/or labeled on the protein maps, thus providing the 1993 update of the human plasma and red blood cell two-dimensional gel SWISS-2DPAGE database. SWISS-2DPAGE and the SWISS-PROT protein sequence databases are closely linked together through the use of common accession numbers.

The focusing positions of polypeptides in immobilized pH gradients can be predicted from their amino acid sequences

The focusing positions in narrow range immobilized pH gradients of 29 polypeptides of known amino acid sequence were determined under denaturing conditions. The isoelectric points of the proteins calculated from their amino acid sequences matched with good accuracy the experimentally determined pI values. We show the advantages of being able to predict the position of a protein of known structure within a two-dimensional gel.

Two-dimensional polyacrylamide gel electrophoresis isolation and microsequencing of Pseudomonas aeruginosa proteins

Outer membrane (OM) proteins of beta-lactam-susceptible and -resistant strains of Pseudomonas aeruginosa were analyzed by 2-D polyacrylamide gel electrophoresis. Carrier ampholytes, pH 4-8, and immobilized pH gradient (IPG), pH 3.5-10.0, procedures were used. An acidic-protein spot (pI = 5.2) detected in susceptible but not in an imipenem-resistant strain was sequenced and twenty-five N-terminal amino acids had total homology with the OM protein D, the imipenem-specific porin of P. aeruginosa. A basic-protein spot (pI = 9.0) detected in ceftazidime-resistant, but not in a susceptible strain was sequenced and fourteen N-terminal amino acids had homology with a beta-lactamase encoded by the ampC gene of P. aeruginosa. The IPG procedure allows identification of more than one hundred proteins of the OM fraction from a single gel. Detection of beta-lactamase in OM fractions might reflect a periplasmic contamination, but its anchorage within the OM cannot be ruled out.

Disulfide bond assignment in human J chain and its covalent pairing with immunoglobulin M

The assignment of disulfide bonds in human J chain and its covalent pairing with immunoglobulin M was determined under conditions which minimize disulfide bond interchange. We show that in J chain the three intradisulfide bridges are formed between Cys 12 and 100, Cys 71 and 91, and Cys 108 and 133. Previous reports [reviewed by Koshland, M. E. (1985) Annu. Rev. Immunol. 3, 425-453] have proposed that cysteines 12, 14, or 68 were linked to the penultimate cysteine 575 of two mu chain tails. In this work, we demonstrate that cysteines 14 and 68 are disulfide-bridged to mu chains. A revised, albeit putative, model of J chain folding is presented which takes into account the correct disulfide pairing and the predictive secondary structure assignment.

Human liver protein map: a reference database established by microsequencing and gel comparison

This publication establishes a reference human liver protein map obtained with immobilized pH gradients. By microsequencing, 57 spots or 42 polypeptide chains were identified. By protein map comparison and matching (liver, red blood cell and plasma sample maps), 8 additional proteins were identified. The new polypeptides and previously known proteins are listed in a table and/or labeled on the protein map, thus providing a human liver two-dimensional gel database. This reference map can be used to identify protein spots on other samples such as rectal cancer biopsies.

Polypeptide marker and disease patterns found while mapping proteins in ascitis

To assess the protein composition of ascitis, 28 samples of ascitic fluid were obtained from patients admitted to Geneva University Hospital. The samples were analysed randomly and blindly by high-resolution two-dimensional polyacrylamide gel electrophoresis. The final visual evaluation was compared with the discharged summary and diagnosis. The protein pattern of ascitis was, as expected, very similar to normal or diseased plasma, with the exception of two spots which were present in ascitic fluids but not in the 200 plasma samples analyzed in parallel. After microsequencing, they proved to be beta-fibrinogen fragments. Several diseases showed distinct patterns, especially acute pancreatitis. A group of intense spots with an apparent molecular mass between those of alpha 1-antitrypsin and beta-haptoglobin were found in all ascitic fluid from pancreatitis cases (six patients). These spots had isoelectric points similar to those of alpha 1-antitrypsin and beta-haptoglobin and microsequencing revealed that they were three different fragments of alpha 1-antitrypsin.