Preliminary investigation of airgap electrospun silk-fibroin-based structures for ligament analogue engineering.

The process of electrospinning has proven to be highly beneficial for use in a number of tissue-engineering applications due to its ease of use, flexibility and tailorable properties. There have been many publications on the creation of aligned fibrous structures created through various forms of electrospinning, most involving the use of a metal target rotating at high speeds. This work focuses on the use of a variation known as airgap electrospinning, which does not use a metal collecting target but rather a pair of grounded electrodes equidistant from the charged polymer solution to create highly aligned 3D structures. This study involved a preliminary investigation and comparison of traditionally and airgap electrospun silk-fibroin-based ligament constructs. Structures were characterized with SEM and alignment FFT, and underwent porosity, permeability, and mechanical anisotropy evaluation. Preliminary cell culture with human dermal fibroblasts was performed to determine the degree of cellular orientation and penetration. Results showed airgap electrospun structures to be anisotropic with significantly increased porosity and cellular penetration compared to their traditionally electrospun counterparts.

Electrospinning-aligned and random polydioxanone-polycaprolactone-silk fibroin-blended scaffolds: geometry for a vascular matrix.

Extracellular matrices are arranged with a specific geometry based on tissue type and mechanical stimulus. For blood vessels in the body, preferential alignment of fibers is in the direction of repetitive force. Electrospinning is a controllable process which can result in fiber alignment and randomization depending on the parameters utilized. In this study, arterial grafts composed of polycaprolactone (PCL), polydioxanone (PDO) and silk fibroin in blends of 100:0 and 50:50 for both PCL:silk and PDO:silk were investigated to determine if fibers could be controllably aligned using a mandrel rotational speed ranging from 500 to 8000 revolutions per minute (RPM). Results revealed that large- and small-diameter mandrels produced different degrees of fiber alignment based on a fast Fourier transform of scanning electron microscope images. Uniaxial tensile testing further demonstrated scaffold anisotropy through changes in peak stress, modulus and strain at break at mandrel rotational speeds of 500 and 8000 RPM, causing peak stress and modulus for PCL to increase 5- and 4.5-fold, respectively, as rotational speed increased. Additional mechanical testing was performed on grafts using dynamic compliance, burst strength and longitudinal strength displaying that grafts electrospun at higher rotational rates produced stiffer conduits which had lower compliance and higher burst strength compared to the lower mandrel rotational rate. Scaffold properties were found to depend on several parameters in the electrospinning process: mandrel rotational rate, polymer type, and mandrel size. Vascular scaffold design under anisotropic conditions provided interesting insights and warrants further investigation.

The impact of ultrasound in suspected acute appendicitis.

AIMS: To evaluate prospectively the impact of an appendix ultrasound (US) service on the clinical management of patients presenting with suspected acute appendicitis. MATERIALS AND METHODS: The referring clinician completed a proforma for patients presenting with suspected acute appendicitis. Two visual analogue scales assessed clinical suspicion before and after knowledge of laboratory results. The clinician also indicated if they intended to operate had US been unavailable. During a 3-year period, 327 patients were examined by graded-compression US and diagnosed "positive" or "negative" for acute appendicitis. Findings were correlated with histopathology results. The referring clinician completed a retrospective audit questionnaire to assess user satisfaction. RESULTS: Clinical suspicion was altered by knowledge of laboratory results. The decision to operate if US had been unavailable, was "yes" in 70 cases (group A), "no" in 231 (group B), and incomplete in 26 (group C). In group A, 31 patients (44.3%) had a negative US and 25 avoided surgery. US identified 39 cases of appendicitis and 37 appendicectomies confirmed appendicitis in 34 cases. In group B, 72 (31.2%) patients had a positive US and 66 appendicectomies confirmed 51 cases of appendicitis. The sensitivity of US was 94.7% in group A, 93.3% in group B and 93.8% overall. Specificity was 90.6% in group A, 91.2% in group B and 91.3% overall. US findings were contrary to intended surgical management in 103 cases. Management was altered in 97 cases (32.2%), with a positive outcome in 85 (28.2%). The referrers found US of appendix very useful in planning appropriate management. CONCLUSION: US of the appendix increases diagnostic accuracy, alters management and is more sensitive and specific than clinical impression, either alone, or in conjunction with laboratory results.

Electrospun polydioxanone-elastin blends: potential for bioresorbable vascular grafts.

An electrospun cardiovascular graft composed of polydioxanone (PDO) and elastin has been designed and fabricated with mechanical properties to more closely match those of native arterial tissue, while remaining conducive to tissue regeneration. PDO was chosen to provide mechanical integrity to the prosthetic, while elastin provides elasticity and bioactivity (to promote regeneration in vitro/in situ). It is the elastic nature of elastin that dominates the low-strain mechanical response of the vessel to blood flow and prevents pulsatile energy from being dissipated as heat. Uniaxial tensile and suture retention tests were performed on the electrospun grafts to demonstrate the similarities of the mechanical properties between the grafts and native vessel. Dynamic compliance measurements produced values that ranged from 1.2 to 5.6%/100 mmHg for a set of three different mean arterial pressures. Results showed the 50:50 ratio to closely mimic the compliance of native femoral artery, while grafts that contained less elastin exceeded the suture retention strength of native vessel. Preliminary cell culture studies showed the elastin-containing grafts to be bioactive as cells migrated through their full thickness within 7 days, but failed to migrate into pure PDO scaffolds. Electrospinning of the PDO and elastin-blended composite into a conduit for use as a small diameter vascular graft has extreme potential and warrants further investigation as it thus far compares favorably to native vessel.

Perineural cysts presenting as complex adnexal cystic masses on transvaginal sonography.

OBJECTIVE: This study describes the sonographic features of sacral perineural cysts that initially presented as adnexal complex cystic masses on transvaginal sonography. CONCLUSION: Perineural cysts may have a complex cystic appearance, including septation and internal debris, on transvaginal sonography. The extraovarian, extraperitoneal, and posterior location on real-time sonography are suggestive features.

Radiological features of epiploic appendagitis and segmental omental infarction.

Epiploic appendagitis and segmental omental infarction are more frequently encountered with the increased use of abdominal ultrasound and Computed tomography (CT) in the radiological assessment of the patient who presents clinically with acute abdominal pain. Recognition of specific imaging abnormalities enables the radiologist to make the correct diagnosis. This is important, as the appropriate management of both conditions is often conservative. Follow-up imaging features correlate with clinical improvement.

Duplex Doppler ultrasonography of lower limb veins: detection of cardiac abnormalities.

AIM: We describe the detection of right sided cardiac abnormalities by Doppler ultrasonography of the lower limb veins. We also attempt to quantify the degree of tricuspid regurgitation (TR) by analysis of the femoral vein Doppler waveform (DW). MATERIALS AND METHODS: The DWs of the lower limb veins were examined in 276 patients over a 17-month period. The detection of abnormal pulsatile DW was compared with echocardiography on these patients. The reports of chest radiographs (CXR) obtained on 104 of the 276 patients were reviewed. RESULTS: Abnormal cardiac pulsatility of the DW was detected in nine patients (3.3%), with abnormally high retrograde velocity peak (RVP) recordings. These abnormal RVPs are compared to RVPs in a normal control group. The RVPs in the abnormal group revealed a statistically significant (Pearson's r = 0.9113) correlation with the degree of TR observed on echocardiography. All nine patients (100%) demonstrated cardiac enlargement on CXR compared to 16 of the 95 (16.8%) with a normal DW and available report of recently performed CXR. CONCLUSION: Doppler ultrasonography of lower limb veins is a frequently performed examination in most Radiology departments. We describe a simple, effective and reproducible ultrasound technique enabling detection of an underlying cardiac abnormality that may provide an estimation of the degree of TR. These important signs should alert the examining radiologist to the presence of an underlying cardiac dysfunction that may require further appropriate cardiac evaluation.McClure, M. J. (2000). Clinical Radiology 55, 533-536.

Wildervanck's syndrome presenting as hemiparesthesia.

A 41-year-old male presented with recent-onset left hemiparesthesia, described as a "tingling numbness" of the upper extremity, torso, and face. History revealed a lifelong horizontal diplopia, neck stiffness, and left-sided hearing loss for 5 months. Examination revealed an ocular exam consistent with Duane's retraction syndrome, clinical and radiographic evidence of congenital fusion of C2 and C3 demonstrative of the Klippel-Feil anomaly, and a sensorineural hearing loss confirmed by audiometry. The diagnosis of Wildervanck's syndrome was made based on this classic triad of findings. A thorough evaluation has not yielded an objective explanation for the episodic hemiparesthesia. We present a patient exhibiting the classic triad of Wildervanck's syndrome, whose presentation is unique because hemiparesthesia has not previously been reported in association with this rare syndrome.

Infant stimulation during hospitalization.

Stimulation is essential to the development of infants and children. They are developing skills related to gross motor, fine motor-adaptive, language, and personal-social functioning. Hospitalization can disrupt the developmental process for infants, even those without pre-existing developmental delays, if intervention is not provided. Hospitalized infants are often subjected to an overabundance of meaningless stimulation or understimulation. Nursing needs to insure provision of meaningful stimulation to help alleviate the effects of hospitalization. Parents and/or significant others need to be included whenever possible. A suggested infant stimulation program for hospitalized infants is presented. Practicality for the pediatric clinician facilitates easy intervention.

Characterization of a new model of GM2-gangliosidosis (Sandhoff's disease) in Korat cats.

We have detected a disorder in Korat cats (initially imported from Thailand) that is analogous to human Sandhoff's disease. Pedigree analysis indicates that this disease in an autosomal recessive disorder in the American Korat. Postmortem studies on one affected cat showed hepatomegaly that was not reported in the only other known feline model of GM2-gangliosidosis type II. Histologic and ultra-structural evaluation revealed typical storage vacuoles. There was a marked deficiency in the activity of hexosaminidase (HEX) A and B in affected brain and liver as compared to controls. Electrophoresis of a liver extract revealed a deficiency of normal HEX A and B in the affected animals. The blocking primary enzyme immunoassay verified the presence of antigenically reactive HEX present in affected cat livers in quantities slightly elevated with respect to the normal HEX concentration in control cats. In leukocytes, obligate heterozygotes had intermediate levels of total HEX activity with a slight increase in the percent activity due to HEX A. Indeed, 4 of 11 phenotypically normal animals in addition to four obligate heterozygotes appear to be carriers using this assay. Affected brain and liver compared with control brain and liver contained a great excess of bound N-acetylneuraminic acid in the Folch upper-phase solids; thin-layer chromatography showed a marked increase in GM2-ganglioside. In summary, we have characterized the pedigree, pathology, and biochemistry of a new feline model of GM2-gangliosidosis which is similar to but different from the only other known feline model.