By L. Falk. LeTourneau University. 2018.
In some schools tutors are deliberately chosen to be non-experts particularly where the Open Discovery approach is predominant order viagra plus 400 mg mastercard erectile dysfunction natural treatments. Small group activities are supported by independent study for which curriculum time must be carefully protected purchase viagra plus 400mg visa erectile dysfunction treatment algorithm. Where tutor resources are limited it is possible to conduct PBL in large group 113 settings using student-led groups for discussion or by relying to a greater degree on independent study. We have used this approach successfully in a foundation course using PBL for first-year medical students (see later). The selection of the problems This is one of the most important considerations in course design. The problems must be of the kind that will ultimately be faced by the students after they graduate but must also be both broad enough and specific enough to engage the students in learning activities which match the curriculum objectives. In general they should be patient problems or health problems which will require students to go through the following process: Analysis of the problem. Identification of the multidisciplinary knowledge re- quired to understand and solve the problem. Obtaining agreement on when the learning tasks will be achieved, Application of the newly acquired knowledge to the initialproblem. While these problems will usually be represented in written form every chance should be taken to engage the students in the same PBL process with real problems encountered in the health care setting. To this end clinical teachers should be actively engaged in supporting the programme. This can be particularly helpful in the earlier parts of the curriculum where opportunities for clinical experience may be more limited. Your first task will be to obtain the objectives if they have been prepared by an overseeing group. Such objectives should define what it is the students should have achieved when they have completed the module (see Chapter 6). It is important to seek the involvement of teachers from all the disciplines that are expected to contribute to the learning outcome of the students. Once objectives are agreed, case summaries must be carefully prepared, remembering that they should be interesting and complex enough to engage students in the problem-solving process. A written guide should be developed for the tutors involved in the module, its content depending to some extent on the familiarity they are likely to have with the problem. Resource people who could be available for students to contact should be approached and times that meetings with students could be scheduled should be ascertained. Assessment This is one area where there is still considerable debate and development. It is important to involve all disciplines in the preparation of assessment materials as it is to engage them in defining the objectives. Only in this way will they be convinced that their discipline is being adequately represented. This reassurance is particularly important to the basic scientists who are often those most threatened by a change to PBL. Constantly challenging the students to evaluate the success of their learning is a vital role of the tutor. A way of approaching this is outlined in Chapter 8 in the section on self-assessment. Conventional knowledge-based tests, such as MCQs, should be avoided except perhaps for student self-assessment or progress testing. Unfortunately, test methods more suitable for PBL courses are not well developed. The Modified Essay Question may be the simplest and most flexible format if a written test of integrated knowledge is required (see Chapter 8). In many schools the tutor is asked to rate students on their performance with the emphasis being as much on their group and personal learning skills as on their grasp of the content. Few methods have been specifically designed to evaluate problem-based self-directed learning skills. The most well known of these is the Triple Jump Test developed at McMaster University. In the first step the student works through a theoretical problem on a one-to-one basis with a tutor, The student is asked to think aloud as the problem is assessed and learning needs determined. The second step consists of a fixed period of time (2-3 hours) during which the student may seek out relevant information. The final step involves a return to the tutor where the new information is used to re-analyse the problem and hope- fully come to some conclusions. The tutor evaluates the efficiency and effectiveness of the student’s problem- solving and self-directed learning skills.
The Lachman test was normal in 32 patients discount viagra plus 400 mg amex erectile dysfunction diabetes cure, grade 1+ in 12 patients purchase viagra plus 400mg with amex erectile dysfunction among young adults, and grade 3+ in two patients. One patient was felt to have mild PCL instability, and two patients had mild posterolateral instability on emergency room testing at 30°. Radiographs were taken of the knees at the two-year follow-up visit to complete the IKDC forms. Tunnels were measured at their widest point, at the aperture, the mid- point, and 1cm from the distal aspect of the tunnel. In 36 of the 49 cases (73%), the X-rays were available for secondary review of the tunnels. The morphology of the tunnel, the width of its widest point, the width of the aperture, and the cross-sectional area were measured and com- pared to mechanical outcome. In these cases, the tibial tunnel was expanded in seven, and femoral tunnel expansion was identiﬁed in seven cases. In six cases, the expansion could be considered to be signiﬁcant, with the widest point of both tunnels measuring 15mm. Four of the ten cases in group C had between 3mm and 5mm of laxity at maximum manual force at the two- year follow-up mark. No signiﬁcant correlations existed by comparison with the Spearman correlation coefﬁcient between ﬁnal IKDC score or KT-score or with the measurements of the tunnels at the aperture, midsection, widest point, or most distant part of the tunnel. In the ﬁve cases where both tunnels measured greater than 15mm, on at least one radiograph, two cases were in the 3mm to 5mm group. From the other perspective, 18 cases with available radiographs at two-years had less than 2mm of laxity, seven had 3mm to 5mm of laxity, and one had greater than 5mm of laxity on a maximum manual force KT examination. In four of the seven cases, the morphology of the tunnel could be classiﬁed as expansive as opposed to cylindrical and ﬁlling in with bone (57%). However in 6 of the 18 cases (33%) with less than 2mm of laxity, similarly expansive tunnels were identiﬁed. The extent of aperture widening did not correlate with clinical laxity or IKDC score at two-year follow-up. Multiple statistical comparisons were made to identify positive pre- dictive factors, which resulted in an increased trend for a patient to fall into the 3mm to 5mm laxity group at two years. Speciﬁcally using post hoc ANOVA, ANCOVA comparisons, Spearman rank correlations, and unpaired two-tailed student t-tests, it was concluded that gender, patient age, the use of secondary tibial ﬁxation, and the magnitude of preoperative instability and laxity could not be associated with an increased KT manual maximum laxity or an increased prevalence of patients in the 3mm to 5mm laxity group. Comparisons were repeated after the exclusion of the revision surgical procedures, but this did not affect the results. The correlation of IKDC scores and gender, use of the secondary tibial button ﬁxation and revision. Activity in sedentary activities (activities of daily living), light activities (nonpivotal sports), moderate activities (tennis, skiing), and strenuous activity (jumping, pivoting sports) were graded by the patients. These subjective scores are com- bined with a mathematical formula to create the IKDC score. Age, gender, and meniscal pathology were not associated with a signiﬁcant change in the IKDC score (Table 10. Patients with greater than 5mm laxity were associated with a signiﬁcantly decreased IKDC score from those with 0mm to 2mm or 3mm to 5mm (p > 0. There was also a trend toward a decreased score in patients with radiographic evidence of degenerative changes (p < 0. Where BioScrew ﬁxation was used in the case of a revision ACL in four cases, a 3mm to 5mm side-to-side difference was obtained in 3 cases, and a greater than 5mm laxity was obtained in 1 case. Discussion There has been a trend among some investigators to shift to an increased reliance on the semitendinosus graft for ACL reconstruction. This has been promoted by multiple studies, which favor its use after Table 10. Lateral Medial Degenerative OA Total menisectomy menisectomy on X-ray IKDC 84. Results consideration of donor site morbidity and rehabilitation without the sacriﬁce of functional outcome. This study served to evaluate the use of the BioScrew for hamstring ACL reconstruction. The screw is made of poly-L-lactide and biode- grades over several years. It has been shown to work well in patellar tendon graft ACL reconstructions. The adaptation of this interference screw technique to this graft has several advantages, including its straightforward technique, the avoidance of graft cutting (previously seen with metal screws), and ultimate resorption of the graft. An addi- tional advantage is that these screws are cannulated, allowing accurate placement of the screws into the appropriate tunnels. These results demonstrate excellent clinical results in terms of patient satisfaction and outcome. The results indicated that 33 patients (67%) had 0mm to 2mm of laxity; 13 patients (27%) had 3mm to 5mm of laxity, and 2 patients (4.
In con- trast to the van der Waals interaction which falls off reciprocally with dis- tance order viagra plus 400mg online erectile dysfunction zoloft, the electrostatic repulsion falls off exponentially with distance viagra plus 400mg with mastercard erectile dysfunction killing me. Consequently, the van der Waals interaction dominates at small and large distances, whilst the double-layer interaction dominates at intermediate distances. GRIFFITHS The maximum in the potential corresponds to the barrier to aggregation – the inherent stability of the dispersion. If this barrier is larger than the thermal energy kT, the dispersion will be stable. The polymer layers, however, also introduces new contributions to the overall interaction between the particles. As two particles approach one another, compression of the polymer layer may occur which is unfavour- able. Associated with this compression, is an increase in the local polymer concentration – this can be favourable or unfavourable depending on the solubility of the polymer. If the polymer layers increases the stability of the dispersion, it is denoted ‘steric stabilisation’. The polymer must fulﬁl two key criteria; (i) the polymer needs to be of sufﬁcient coverage to coat all the particle sur- faces with a dense polymer layer, and (ii) the polymer layer is ﬁrmly attached to the surface. How this is engineered is beyond the scope of this article, but the consequences of not satisfying these criteria are informa- tive in understanding the effect that polymers have on the overall interpar- ticle interaction. Since complete or incomplete coverage of the particles results in very different properties (i. The presence of insufﬁcient but very large polymers can also reduce the stability. When the particles attain a separation such that the polymer layers on an adjacent particles may bridge between the particles, a favour- able interaction occurs and a loss of stability ensues. A non-adsorbing polymer in solution can also destabilise a dispersion through a mechanism called depletion ﬂocculation. When polymer mole- cules do not interact favourably with the particle surfaces from an enthal- pic perspective, they are repelled from the surface regions due to entropic reasons. A ‘depletion zone’ around the particles is created which has a lower average polymer concentration than the bulk solution. The osmotic The secret of Nature’s microscopic patterns 105 pressure difference results in solvent being pulled from the depletion zone in essence, pulling the particles closer together. Interactions involving surface poly- mers are of great interest in explaining biological microarchitectures as in many cases, the likely components will be separated from the supporting ﬂuids by mixed polymeric membranes involving lipids, proteins and poly- saccharides. Another important interaction that needs to be considered is the ‘hydrophobic interaction’. This can be most easily thought of in terms of two immiscible liquids such as oil and water being induced to mix by adding surfactants, to form (micro) emulsions. The exact structure of the phase formed depends heavily on the relative compositions of the various phases and the structure of the surfactant (see Figure 6. Below some critical surfactant concentration, the system is two-phase with excess oil or water depending on the oil/water concentration. On adding more surfactant, the system moves into a one-phase region with normal micelles forming in water-rich systems. The water constitutes the continuous phase, solvating the headgroups of the surfactant whose hydro- phobic tails solubilise oil in the core of the micelle. Schematic phase diagram for a three-component (oil, water, surfactant) system showing some of the self-assembled structures which form in the various regions. Ultimately, at high surfactant compositions, liquid crystalline (lamellar) structures form. If a polymerisation occurs within one such structure, the resulting (polymer) architectures will probably closely resemble the self-assembled ones formed in our artiﬁcial sporangia. To cause ﬂocculation of the particles, carboxymethylcellulose (CMC) was intro- duced with the intention of initiating a depletion interaction as described above. Although different from sporopollenin, polystyrene shares some properties and is at least reasonably well understood with regard to its col- loidal behaviour. These initial experiments proved successful and resulted in the formation of colloidal crystals like those within the spore walls, but more signiﬁ- cantly, they were built by processes and components which we believe behave in a similar manner to those in the natural system. Similar particle ﬂocculations, but of an amorphous nature and formed from particles of inconsistent size could be produced by either depletion or bridging ﬂoccu- lation. Subsequent experiments have utilised hydrocarbons and lipids (known from the natural system of wall production) to synthesise mimics resembling other types of spore wall with some success. It is disconcerting how ‘life-like’ some structures built from synthetic colloidal particles can be (Figures 6. Experiments involving mimics of sporopollenin (the principal component of spore walls) demonstrate that patterns very similar, if not identical to those of natural spores and pollen, can be produced from mixtures containing colloidal particles.
Responses to an agent are sometimes dramatic buy discount viagra plus 400 mg line erectile dysfunction facts and figures, but more often the improvements are incremental buy generic viagra plus 400mg erectile dysfunction doctors huntsville al. In patients with substantial myoclonus, the combination of pharmacologic and nonpharmacologic measures can be effective. Therapeutic failure should prompt re-evaluation of the diagnosis and treatment plan and a search for exacerbating factors. In the end, sensitivity to quality of life issues can be the most important contribution a clinician can make. Shibasaki H, Ikeda A, Nagamino T, et al: Cortical reﬂex negative myoclonus. Cohn Johns Hopkins Hospital, Children’s Center, McKusick-Nathans Institute of Genetic Medicine, Baltimore, Maryland, U. A number of clinically distinct disorders of muscle manifest abnormalities in other organs, most often the brain. The most common of these, Duchenne muscular dystrophy, is discussed in a separate chapter. The disorders that predominantly affect muscle, but manifest with distinctive abnormalities of brain as well, likely do so because of widespread gene expression and other commonalities of brain and muscle. Other than their shared tissue vulnerabilities, there is a wide range of apparent gene function between these disorders. This is a rapidly expanding area of clinical and fundamental neuroscience, and more disorders and a better understanding of those disorders already described is virtually certain in the next few years. DISORDERS OF PROTEIN GLYCOSYLATION, ‘‘DYSTROGLYCANOPATHIES’’ There has been a recent explosion in the identiﬁcation of neuromuscular diseases caused by mutations in genes that affect carbohydrate metabolism or protein glyco- sylation. A number of these ﬁndings relate to defects in the O-glycosylation of a-dystroglycan. Alpha dystroglycan plays a pivotal role within the dystrophin–glycoprotein complex (DGC), which represents a major factor for muscle ﬁber stability upon con- traction. Identiﬁcation of gene mutations within the DGC and the association with Duchenne=Becker muscular dystrophy and other forms of limb–girdle and congeni- tal muscular dystrophy have dominated the clinical and research ﬁeld for years. Recently, the focus has shifted to post-translational modiﬁcations of proteins, as genes encoding proteins involved in glycosylation have deﬁned a new area of attention in muscular dystrophy. Although the function of most glycosylation is poorly understood, many vertebrate proteins are post-translationally modiﬁed by carbohydrates and it has been estimated that 1% of human genes encode enzymes involved in oligosaccharide synthesis and function. A deﬁciency in post-translational modiﬁcation of a-dystroglycan has now been characterized as a common feature in several forms of muscular dystrophy associated with central nervous system 161 162 Cohn abnormalities. It needs to be emphasized that these types of muscular dystrophies appear to be distinct from the congenital disorders of glycosylation (CDG syn- dromes), a group of diseases that often leads to multisystem disease caused by defects in the well-characterized N-glycosylation pathways as opposed to the less deﬁned O-glycosylation pathways. The majority of patients with muscular dystrophy and associated structural brain morphology present with fairly nonspeciﬁc symptoms such as profound hypo- tonia usually at the time of birth suggesting that abnormalities of skeletal muscle and the central nervous system have occurred in utero during early development. Thus, a fairly extensive initial diagnostic workup of the hypotonic infant is generally needed to distinguish this patient group from patients with other causes of neonatal hypo- tonia such as central nervous system hemorrhage, infection, or neurometabolic diseases. Abnormalities of serum creatine kinase, a myopathic pattern of electromyogra- phy (even in the presence of a normal serum creatine kinase) and any abnormal structural abnormalities detected on CT scan or preferably on MRI should prompt the clinician to perform a skeletal muscle biopsy and consider the above mentioned group of dystroglycanopathies as a potential differential diagnosis (Table 1). The skeletal muscle biopsy generally reveals classic signs of muscular dystrophy involving signs of degeneration and regeneration with centrally located nuclei, ﬁbrosis and fat Table 1 Overview of Clinical and Molecular Forms of Dystroglycanopathies Associated with Central Nervous System Disease Gene= Dystroglycanopathy Inheritance protein Clinical ﬁndings Muscle eye brain AR POMGnT1 Severe muscle weakness, mental disease (MEB) retardation, epilepsy, neuronal migration disorder, ocular abnormalitiesa Walker Warburg AR POMT1 Severe muscle weakness, death syndrome (WWS) usually in infancy, severe psychomotor developmental delay, mental retardation epilepsy, neuronal migration disorder, ocular abnormalitiesa Fukuyama congenital AR Fukutin Severe axial and proximal muscle muscular dystrophy weakness, mental retardation, (FCMD) epilepsy, neuronal migration disorder Congenital muscular AR FKRP Variable muscle weakness, cerebellar dystrophy 1C abnormalities cardiomyopathy (MDC1C) Congenital muscular AR LARGE Variable muscle weakness, dystrophy 1D (MDC1D) profound mental retardation, white matter changes, subtle neuronal migration disorder a Ocular abnormalities may include congenital myopia, glaucoma, pallor of optic discs, retinal hypoplasia. Abbreviations: AR, autosomal recessive; POMGnT1, protein O-mannose b-1,2-N-acetylglucosaminyl- transferase; POMT1, protein O-mannosyltransferase; FKRP, fukutin-related protein; LARGE, putative glycosyltransferase. In addition, immunohistochemical analysis with antibodies directed towards a-dystroglycan exhibits loss or signiﬁcantly reduced expression of a-dystroglycan at the sarcolemma of the muscle ﬁbers. Currently, enzymatic tests and mutational screening are being developed for clinical use in order to conﬁrm the clinical=immunohistological diagnosis of dystroglycanopathies. All the patients within this disease spectrum who also have structural abnormalities of the brain show mild to severe mental retardation. Patients diagnosed with Walker Warburg syndrome are most severely affected and usually die within the ﬁrst few years of life. In contrast, patients within the MDC1C and 1D group (Table 1) can have milder phenotypes particularly in respect to their muscle power. Clinical care is thus directed to supportive and preventative therapy, aiming to prevent secondary sequalae from signiﬁcant muscle weakness such as joint contractures and chronic respiratory hypoventilation. Therefore, close collaboration with physical therapists, orthopedic surgeons, and pulmonologists is a signiﬁcant part of management for these patients. Current research is directed towards enzyme therapy in an effort to potentially modify the aberrant glycosylation of a-dystroglycan. CONGENITAL MUSCULAR DYSTROPHY DUE TO LAMININ a2 DEFICIENCY This form of congenital muscular dystrophy is associated with early onset of weak- ness, often very severe, that is thereafter largely stable with good supportive care. A distinctive abnormality of white matter on MRI and CT imaging ﬁrst suggests profound leukodystrophy, but there is no intellectual or other detectable consis- tent abnormality in CNS function.
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