The Facioscapulohumeral muscular dystrophy region on 4qter and the homologous locus on 10qter evolved independently under different evolutionary pressure

Background  

The homologous 4q and 10q subtelomeric regions include two distinctive polymorphic arrays of 3.3 kb repeats, named D4Z4. An additional BlnI restriction site on the 10q-type sequence allows to distinguish the chromosomal origin of the repeats. Reduction in the number of D4Z4 repeats below a threshold of 10 at the 4q locus is tightly linked to Facioscapulohumeral Muscular Dystrophy (FSHD), while similar contractions at 10q locus, are not pathogenic. Sequence variations due to the presence of BlnI-sensitive repeats (10q-type) on chromosome 4 or viceversa of BlnI-resistant repeats (4q-type) on chromosome 10 are observed in both alleles.     

An in vivo role for Trypanosoma cruzi calreticulin in antiangiogenesis

Angiogenesis leads to neovascularization from existing blood vessels. It is associated with tumor growth and metastasis and is regulated by pro- and antiangiogenic molecules, some of them currently under clinical trials for cancer treatment. During the last few years we have cloned, sequenced and expressed a Trypanosoma cruzi calreticulin gene (TcCRT). Its product, TcCRT, a 45 kDa protein, is more than 50% identical to human CRT (HuCRT). TcCRT, present on the surface of trypomastigotes, binds both C1q and mannan binding lectin and inhibits the classical activation pathway of human complement. Since TcCRT is highly homologous to a functional antiangiogenic fragment from HuCRT (aa 120–180), recombinant (r) and native (n) TcCRT were tested in their antiangiogenic effects, in the chick embryonic chorioallantoid membrane (CAM) assay. Both proteins mediated highly significant antiangiogenic effects in the in vivo CAM assay. This effect was further substantiated in experiments showing that the plasmid construct pSecTag/TcCRT also displayed significant antiangiogenic properties, as compared to the empty vector. Most likely, the fact that antiangiogenic substances act preferentially on growing neoplasic tissues, but not on already established tumors, is due to their effects on emerging blood vessels. The results shown here indicate that TcCRT, like its human counterpart, has antiangiogenic properties. These properties may explain, at least partly, the reported antineoplasic effect of experimental T. cruzi infection.     

Differential Effects of Thalidomide on Angiogenesis and Tumor Growth in Mice

Thalidomide, clinically used as an antiinflammatory and antitumoral drug, inhibited sponge-induced angiogenesis when administered systemically (100 mg/kg^–1) in mice. However, it failed to inhibit solid Ehrlich tumor in the same mouse strain. We have used functional, biochemical and histological parameters to assess neovascularization and fibrovascular tissue infiltration of the mice sponge granuloma. The neovascularization growth as detected by development of blood flow and hemoglobin content extracted from the implants showed that thalidomide inhibited fibrovascular tissue formation by 40%. The functional and biochemical parameters correlated well with the histological study. Thalidomide had no inhibitory effect in the development of Ehrlich tumor. The detection of this selective action using the same animal strain bearing two different processes, supports the hypothesis that rather than species specificity, thalidomide is tissue specific. This approach may be used to identify the specificity of other therapeutic agents against distinct angiogenesis-dependent diseases.     

Compartmental Analysis of Breathing in the Supine and Prone Positions by Optoelectronic Plethysmography

Optoelectronic plethysmography (OEP) has been shown to be a reliable method for the analysis of chest wall kinematics partitioned into pulmonary rib cage, abdominal rib cage, abdomen, and right and left side in the seated and erect positions. In this paper, we extended the applicability of this method to the supine and prone positions, typically adopted in critically ill patients. For this purpose we have first developed proper geometrical and mathematical models of the chest wall which are able to provide consistent and reliable estimations of total and compartmental volume variations in these positions suitable for clinical settings. Then we compared chest wall (CW) volume changes computed from OEP( V _CW) with lung volume changes measured with a water seal spirometer (SP) ( V _SP)in 10 normal subjects during quiet (QB) and deep (DB) breathing on rigid and soft supports. We found that on a rigid support the average differences between V _SP and V _CW were –4.2% ± 6.2%, –3.0% ± 6.1%, –1.7% ±7.0%, and –4.5% ± 9.8%, respectively, during supine/QB, supine/DB, prone/QB, and prone/DB. On the soft surface we obtained –0.1% ± 6.0%, –1.8% ± 7.8%, 18.0% ± 11.7%, and 10.2% ± 9.6%, respectively. On rigid support and QB, the abdominal compartment contributed most of the V _CW in the supine (63.1% ± 11.4%) and prone (53.5% ± 13.1%) positions. V _CW was equally distributed between right and left sides. In the prone position we found a different chest wall volume distribution between pulmonary and abdominal rib cage (22.1% ± 8.6% and 24.4% ± 6.8, respectively) compared with the supine position (23.3% ± 9.3% and 13.6% ± 3.0%). © 2001 Biomedical Engineering Society. PAC01: 8763Lk, 8719Uv     

Evaluation of Etest strips for rapid susceptibility testing of Mycobacterium tuberculosis

In this study, our objective was to evaluate Etest strips containing exponential gradients of isoniazid (INH), rifampin (RIF), and streptomycin (STR) for susceptibility testing of Mycobacterium tuberculosis. M. tuberculosis isolates were tested for antimicrobial susceptibilities by the standard proportion method using L?wenstein-Jensen (LJ) medium and by the Etest. The MICs determined by the Etest were obtained at 5, 7, or 10 days. In some strains with Etest-discrepant results, radiometric susceptibility testing (BACTEC) was performed to determine a consensus result. M. tuberculosis concordance between the two methods was 97% (86 of 89 isolates) for RIF, 96% for INH (84 of 87 isolates), and 80% (61 of 76 isolates) for STR. Most of the MICs determined by the Etest were easy to interpret and readable within 5 days. Results correlated well with those obtained by the LJ proportion and BACTEC methods for INH and RIF. However, a high proportion of false-sensitive and false-resistant results were observed, most often for STR. We also observed that variations in the inoculum size of M. tuberculosis isolates affected the MICs to a substantial degree. These discrepancies, along with the expense of the media, the Etest strips, and the specialized equipment required (CO2 incubator), make this method less useful in developing countries.     

Firing of inferior colliculus neurons in response to low-frequency sound stimulation during sleep and waking

SUMMARY  In vivo extracellular recordings of 102 units in the central nucleus of the inferior colliculus (IC), were made in chronically implanted guinea-pigs during the sleep/wake cycle. During wakefulness, the units were classified according to their response characteristics. Most neurons (63%) recorded showed changes, increasing or decreasing in the number of evoked discharges during the animal's transitions between wakefulness and slow-wave sleep. In the paradoxical sleep phase, the result was similar; changes were observed in most neurons, while only 11% of units did not shift their discharge pattern during ipsilateral sound stimulation.
The post-stimulus time histogram of the overall evoked pattern of discharge showed sleep/wake dependency, i.e. changed in 35% of the units recorded during the 50 ms of sound stimulation.
Fifty-five percent of auditory neurons did not show any change in the spontaneous firing rate during slow-wave sleep as compared to the previous waking period, while 22% exhibited a discharge increase and 23% decreased their firing. During paradoxical sleep, 14 out of 17 cells increased their spontaneous firing rate. The IC auditory neurons send descending connections to regions such as the dorsal pontine nuclei, known to mediate sleep processes. Thus, for constant auditory input, the firing rate or number of discharge variations are due to functional shifts in the sleeping brain. Auditory processing is present during sleep and differs from that observed during wakefulness. Differences were observed in the evoked firing number and/or spontaneous rate, as well as in the pattern of discharge. The ultimate reason for auditory unit shifts during sleep remains yet unexplained.     

The behavior of novel hydrophilic composite bone cements in simulated body fluids

Composite bone cements were formulated with bioactive glass (MgO--SiO(2)--3CaO. P(2)O(5)) as the filler and hydrophilic matrix. The matrix was composed of a starch/cellulose acetate blend (SCA) as the solid component and a mixture of methylmethacrylate/acrylic acid (MMA/AA) as the liquid component. The curing parameters, mechanical properties, and bioactive behavior of these composite cements were determined. The addition of up to 30 wt % of glass improved both compressive modulus and yield strength and kept the maximum curing temperature at the same value presented by a typical acrylic-based commercial formulation. The lack of a strongly bonded interface (because no coupling agent was used) had important effects on the swelling and mechanical properties of the novel bone cements. However, bone cements containing AA did not show a bioactive behavior, because of the deleterious effect of this monomer on the calcium phosphate precipitation on the polymeric surfaces. Formulations without AA were prepared with MMA or 2-hydroxyethyl methacrylate (HEMA) as the liquid component. Only these formulations could form an apatite-like layer on their surface. These systems, therefore, are very promising: They are bioactive, hydrophilic, partially degradable, and present interesting mechanical properties. This combination of properties could facilitate the release of bioactive agents from the cement, allow bone ingrowth in the cement, and induce a press-fitting effect, improving the interfaces with both the prosthesis and the bone.