Lumbar erector spinae oxygenation during prolonged contractions: implications for prolonged work

Owing to the recent interest in torso stabilization exercises together with many questions regarding the duration of prolonged isometric holds in occupational settings, the authors attempted to assess the level of back muscle oxygenation during prolonged isometric contractions. Specifically, this study recorded relative oxygen saturation of haemoglobin/myoglobin using Near Infrared Spectroscopy (NIRS) in the L3 erector mass during prolonged isometric contractions at intensities from 2 to 30% of maximum voluntary contraction (MVC). It was hypothesized that available oxygen to these muscles is severely compromised even at moderate levels of activation observed in occupational work. Eight volunteers without a history of lower back pain or injury participated in this study. The exercise task involved isometric contraction of the lower erector spinae at five different levels of each subject's maximal voluntary contraction: 2, 5, 10, 20 and 30% MVC, presented in random order. Subjects were placed in a sitting position, with a curved plastic plate secured horizontally to the pelvis to minimize movement at the hip joint. During extensor exertions, they were restrained with a harness that was attached at chest level to a load cell. Each isometric contraction was performed for 30 s followed by 1 min of rest. All levels of contraction demonstrated reduction in oxygen. Given the concern for motion artefact on the NIRS signal, sham trials were conducted where the subjects went through the procedure of attaching the pulling cable but no active pull was performed. These trials showed no change in the NIRS signal. At this time NIRS appears to be the only non-invasive instrumentation available to indicate total available muscle oxygen during low level, prolonged work. Although the specific tissue volume sampled by NIRS cannot be positively identified, it appears that tissue oxygenation in the lumbar extensor musculature is reduced as a function of contraction intensity, even at levels as low as 2% of MVC. These data have implications for prolonged work where postures requiring isometric contractions are sometimes held for hours, and where musculoskeletal illness has been linked to prolonged contraction levels above 2%MVC--these data suggest a possible biological pathway.     

Automatic 3-D segmentation of internal structures of the head in MR images using a combination of similarity and free-form transformations: Part II, validation on severely atrophied brains

Studies aimed at quantifying neuroanatomical differences between populations require the volume measurements of individual brain structures. If the study contains a large number of images, manual segmentation is not practical. This study tests the hypothesis that a fully automatic, atlas-based segmentation method can be used to quantify atrophy indexes derived from the brain and cerebellum volumes in normal subjects and chronic alcoholics. This is accomplished by registering an atlas volume with a subject volume, first using a global transformation, and then improving the registration using a local transformation. Segmented structures in the atlas volume are then mapped to the corresponding structures in the subject volume using the combined global and local transformations. This technique has been applied to seven normal and seven alcoholic subjects. Three magnetic resonance volumes were obtained for each subject and each volume was segmented automatically, using the atlas-based method. Accuracy was assessed by manually segmenting regions and measuring the similarity between corresponding regions obtained automatically. Repeatability was determined by comparing volume measurements of segmented structures from each acquisition of the same subject. Results demonstrate that the method is accurate, that the results are repeatable, and that it can provide a method for automatic quantification of brain atrophy, even when the degree of atrophy is large.     

4-Defect repair of grade 4 cystocele

PURPOSE: The 4-defect repair of grade 4 cystocele corrects discrete and severe deficiencies of vesicourethral support. We describe this technique used during pelvic reconstruction in 130 women. MATERIALS AND METHODS: During a 3-year period 130 patients (age range 35 to 96 years) underwent repair of grade 4 cystocele using the 4-defect repair technique. Cystocele repair had been performed in 60 patients (46%) and hysterectomy had been performed in 85 (65%). A "goalpost incision" is used in the vaginal wall to facilitate separation of the wall from underlying perivesical fascia, entry into the retropubic space, and exposure of the urethropelvic ligament, cardinal ligament and perivesical fascia. The 4 polypropylene sutures are used to provide an anterior vaginal wall sling which is modified to incorporate perivesical fascia and cardinal ligaments. Central defect repair is achieved by approximation of the cardinal ligaments and midline plication of the perivesical fascia over absorbable mesh. RESULTS: A total of 112 patients were available for followup which ranged from 6 to 42 months (mean 21). Repair of grade 4 cystocele was accompanied by other transvaginal repairs in 94 patients (83%), including rectocele repair in 81, hysterectomy in 22 and enterocele repair in 31. Of the patients 92% had excellent objective and subjective results for anatomical cystocele repair. Of the patients with preoperative stress urinary incontinence 90% had excellent or good subjective results. De novo urge incontinence was seen in 7% of patients. CONCLUSIONS: The 4-defect repair technique relies on anatomical restoration of 4 distinct deficiencies of pelvic support and is highly effective for relief of symptoms of grade 4 cystocele.     

Tyrosine-dependent and -independent mechanisms of STAT3 activation by the human granulocyte colony-stimulating factor (G-CSF) receptor are differentially utilized depending on G-CSF concentration

The granulocyte colony-stimulating factor receptor (G-CSF-R) activates multiple STAT proteins. Although the membrane-proximal cytoplasmic region of the G-CSF-R is necessary and sufficient for activation of STAT1 and STAT5, activation of STAT3 requires the membrane distal region that contains four tyrosines. Although one of these (Y704) has previously been shown to be involved in STAT3 activation from a truncated G-CSF-R derived from a patient with severe chronic neutropenia (SCN), this tyrosine is not required for STAT3 activation by the full-length G-CSF-R. To investigate possible alternative mechanisms of STAT3 activation, we generated a series of Ba/F3 cell transfectants expressing the wild-type G-CSF-R or mutant receptors that either completely lack tyrosines or retain just one of the four cytoplasmic tyrosines of the G-CSF-R. We show that, at saturating G-CSF concentrations, STAT3 activation from the full-length G-CSF-R is efficiently mediated by the C-terminal domain in a manner independent of receptor tyrosines. In contrast, at low G-CSF concentrations, Y704 and Y744 of the G-CSF-R play a major role in STAT3 activation. Both tyrosine-dependent and -independent mechanisms of STAT3 activation are sensitive to the Jak2 inhibitor AG-490, follow similar kinetics, and lead to transactivation of a STAT3 reporter construct, indicating functional equivalence. STAT3 activation is also impaired, particularly at nonsaturating G-CSF concentrations, in bone marrow cells from mice expressing a truncated G-CSF-R (gcsfr-triangle up715). These findings suggest that G-CSF-induced STAT3 activation during basal granulopoiesis (low G-CSF) and "emergency" granulopoiesis (high G-CSF) are differentially controlled. In addition, the data establish the importance of the G-CSF-R C-terminus in STAT3 activation in primary cells, which has implications for understanding why truncated G-CSF-R derived from SCN patients are defective in maturation signaling.     

Involvement of heme components in sterol metabolism ofSaccharomyces cerevisiae

There is an intimate association between sterol biosynthesis in yeast and aerobicity. Besides the requirement for molecular oxygen for the epoxidation of squalene, cytochrome hemoproteins are involved in demethylation and desaturation steps. Regulatory effects of hemes on sterol formation have been demonstrated using specifically defective mutants of yeast. Heme competency participates in a mechanism whereby wild-type cells are prevented from taking exogenous sterols from the growth media. The multiple interactions of hemes and sterols appear to be associated with the variously defined functions for sterols in the yeast cells. Based on a paper presented at the Symposium on Plant and Fungal Sterols: Biosynthesis, Metabolism and Function, held at the AOCS Annual Meeting, Baltimore, MD, April 1990.     

A resolution comparison of several time-frequency representations

Two signal components are considered resolved in a time-frequency representation when two distinct peaks can be observed. The time-frequency resolution limit of two Gaussian components, alike except for their time and frequency centers, is determined for the Wigner distribution, the pseudo-Wigner distribution, the smoother Wigner distribution, the squared magnitude of the short-time Fourier transform, and the Choi-Williams distribution. The relative performance of the various distributions depends on the signal. The pseudo-Wigner distribution is best for signals of this class with only one frequency component at any one time, the Choi-Williams distribution is most attractive for signals in which all components have constant frequency content, and the matched filter short-time Fourier transform is best for signal components with significant frequency modulation. A relationship between the short-time Fourier transform and the cross-Wigner distribution is used to argue that, with a properly chosen window, the short-time Fourier transform of the cross-Wigner distribution must provide better signal component separation that the Wigner distribution     

Proteolytic cleavage and activation of PAK2 during UV irradiation-induced apoptosis in A431 cells

Exposure of mammalian cells to ultraviolet (UV) light elicits a cellular response and can also lead to apoptotic cell death. In this report, we show that a 36-kDa myelin basic protein (MBP) kinase detected by an in-gel kinase assay can be dramatically activated during the early stages of UV irradiation-triggered apoptosis of A431 cells. Immunoblot analysis revealed that this 36-kDa MBP kinase could be recognized by an antibody against the C-terminal regions of a family of p21Cdc42/Rac-activated kinases (PAKs). By using this antibody and a PAK2-specific antibody against the N-terminal region of PAK2 as studying tools, we further demonstrated that UV irradiation caused cleavage of PAK2 to generate a 36-kDa C-terminal catalytic fragment and a 30-kDa N-terminal fragment in A431 cells. The appearance of the 36-kDa C-terminal catalytic fragment of PAK2 matched exactly with the activation of the 36-kDa MBP kinase in A431 cells upon UV irradiation. In addition, UV irradiation also led to activation of CPP32/caspase-3, but not ICH-1L/caspase-2 and ICE/caspase-1, in A431 cells and the kinetics of activation of CPP32/caspase-3 appeared to correlate well with that of DNA fragmentation and of cleavage/activation of PAK2, respectively. Moreover, blockage of activation of CPP32/caspase-3 by pretreating the cells with two specific tetrapeptidic inhibitors for caspases (Ac-DEVD-cho and Ac-YVAD-cmk) could significantly attenuate the extent of cleavage/activation of PAK2 induced by UV irradiation. Collectively, the results demonstrate that cleavage and activation of PAK2 can be induced during the early stages of UV irradiation-triggered apoptosis and indicate the involvement of CPP32/caspase-3 in this process.     

New protein genetic studies in six Amazonian Indian populations

A total of 732 individuals affiliated with six Amazonian Indian populations were variously studied in relation to 26 protein genetic systems. Eleven of them were found to be monomorphic in these groups, in accordance with previous investigations. Similarities and dissimilarities (the latter involving the Rh, Duffy, haptoglobin and transferrin systems) were observed in relation to earlier investigations in four of these populations (Galibi, Palikour, Mundurucu and Tenharim). A dimeric, cathodal variant of albumin was found among two Galibi subjects, and the fairly common occurrence of CP* ACAY among some South American Indian populations was confirmed. The results in the six populations were compared with those from 29 others. When relationships are searched for among tribes of the same linguistic group, the factor that seems to be most influential is geographical localization, an exception being the pattern observed among the Cayapo subgroups. The latter shows genetic differences of the same level of magnitude as those observed among Ge-speaking tribes.     

The effect of intravenous and oral fluconazole on the pharmacokinetics and pharmacodynamics of intravenous alfentanil

The growth-promoting activity of PDGF-BB was studied on the adult osteoclasts in the present study. The PDGF receptor beta was detected on the osteoclast membrane through immunohistochemistry (LSAB method) and immunomicroscopy. The PDGF-BB was exerted on the osteoclasts that adhered to the bone slice at concentrations of 0, 10, 20, 30, and 40 ng/ml. The volume of Howship's lacuna augmented significantly and the number of resorption pits also increased with its dose (p < 0.01). The activity of both total acid phosphatase (ACP) and tartrate-resistant acid phosphatase (TRAP) increased significantly. These results suggest that PDGF-BB promotes adult osteoclastic bone resorption directly through PDGF receptor beta and is believed to play important roles in the bone healing process and reconstruction.     

Ruthenium-106 brachytherapy for peripheral retinal capillary hemangioma

OBJECTIVE: This study aimed to evaluate the efficacy and safety of ruthenium-106 brachytherapy of large peripheral retinal capillary hemangiomas. DESIGN: A retrospective case series. PARTICIPANTS: In 25 eyes of 24 patients, peripheral capillary retinal hemangiomas were treated. INTERVENTION: Brachytherapy using 106-ruthenium/106-rhodium plaques was performed. MAIN OUTCOME MEASURES: Eyes were reviewed for hemangioma regression after brachytherapy, occurrence of retinal detachment, requirement of additional vitreoretinal surgery, final visual outcome, and final retinal status. RESULTS: Preoperative mean visual acuity of all eyes treated was 20/60, mean hemangioma diameter was 3.8 mm, corresponding to approximately 2 disc diameters. In 14 eyes, the retina was attached before surgery, 8 eyes showed an exudative detachment, and 3 eyes showed a traction detachment. Fifteen patients had definite von Hippel-Lindau syndrome. Twenty-three of 25 hemangiomas could be destroyed by single brachytherapy. In 16 eyes, a favorable outcome could be achieved. In nine eyes, outcome was unfavorable, characterized by a severe drop in visual acuity, a persisting exudative retinal detachment, or a recurrent traction detachment. In one eye requiring repeated brachytherapy, irradiation retinopathy occurred. Hemangiomas up to a size of approximately 5.0 mm without preoperative exudative detachment could be treated safely by brachytherapy, whereas a larger hemangioma size or a pre-existing exudative retinal detachment predisposed to an unfavorable outcome. CONCLUSION: Solitary peripheral retinal hemangioma can be ablated effectively by ruthenium-106 brachytherapy. A favorable outcome can be expected if the hemangioma diameter is 5.0 mm or smaller and if there is no preoperative exudative retinal detachment.