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Biomedical subjects

J Hough

Publications and source records attributed to J Hough.

At least 19 recordsLinked to original sources
PubMed2006

Dynamic production of hypoxia-inducible factor-1alpha in early transplanted islets.

More than half of transplanted beta-cells undergo apoptotic cell death triggered by nonimmunological factors within a few days after transplantation. To investigate the dynamic hypoxic responses in early transplanted islets, syngeneic islets were transplanted under the kidney capsule of balb/c mice. Hypoxia-inducible factor-1alpha (HIF-1alpha) was strongly expressed at post-transplant day (POD) 1, increased on POD 3, and gradually diminished on POD 14. Insulin secretion decreased on POD 3 in association with a significant increase of HIF-1alpha-related beta-cell death, which can be suppressed by short-term hyperbaric oxygen therapy. On POD 7, apoptosis was not further activated by continually produced HIF-1alpha. In contrast, improvement of nerve growth factor and duodenal homeobox factor-1 (PDx-1) production resulted in islet graft recovery and remodeling. In addition, significant activation of vascular endothelial growth factor in islet grafts on POD 7 correlated with development of massive newly formed microvessels, whose maturation is advanced on POD 14 with gradual diminution of HIF-1alpha. We conclude that (1) transplanted islets strongly express HIF-1alpha in association with beta-cell death and decreased insulin production until adequate revascularization is established and (2) early suppression of HIF-1alpha results in less beta-cell death thereby minimizing early graft failure.

Animals↗
PubMed2003

True acquired left ventricular aneurysms in childhood.

AIM: True left ventricular aneurysms are rarely encountered in childhood. Etiological factors are varied and often indeterminable. There is a paucity of literature detailing the surgical techniques used to repair pediatric aneurysms. METHODS: Three children aged 21 months, 19 months and 5 years with true left ventricular aneurysms underwent surgical repair in our unit. The clinical details, surgical technique, histological review, hospital outcome and short term follow-up is discussed. RESULTS: Two patients underwent repair of their aneurysms by means of the Cooley endoaneurysmorraphy technique, and 1 patient underwent repair using the aneurysm resection and linear plication technique. Histological examination revealed tuberculosis to be the etiological factor in one patient, while a non-specific vasculitis was present in the other 2 patients. Immediate postoperative course was uneventful and all 3 patients were discharged from hospital within one week. Two patients were recatheterized during follow-up visits. All patients were asymptomatic at 1 year follow-up. Echocardiography demonstrated good left ventricular function with disappearance of preoperative mitral regurgitation. CONCLUSION: Pediatric left ventricular aneurysms may be successfully repaired using standard operative techniques. These techniques render excellent short-term RESULTS: Longer follow-up is needed to fully evaluate the outcome of these children.

Cardiac Surgical Procedures↗
PubMed2002

Evaluation of kangaroo pericardium as an alternative substitute for reconstructive cardiac surgery.

BACKGROUND: Bioprosthetic materials (human, bovine and porcine) are used in various cardio-thoracic repair and replacement procedures because of excellent performance and low thrombogenicity. These bioprosthetic substitutes fail due to degeneration and calcification. This study examines the morphology, tensile properties and calcification potential of kangaroo pericardium in vitro and in vivo. METHODS: Bovine (control tissue) and kangaroo pericardium, fixed in 0.625% buffered glutaraldehyde, were examined by light and scanning electron microscopy. A standard method was used for biaxial testing. Pericardial strips (10 x 5 mm) were implanted subcutaneously into male Wistar rats and retrieved after 4, 6 and 8 weeks and examined by Von Kossa's stain technique and atomic absorption spectrophotometry. RESULTS: Histology revealed serosa and fibrosa cell layers in both tissues. Electron microscopy showed a densely arranged collagen matrix in kangaroo pericardium. Kangaroo pericardium calcified significantly less than bovine pericardium at 4 weeks (0.80+/-0.28 versus 21.60+/-4.80 microg/mg) at 6 weeks (0.48+/-0.08 versus 32.80+/-14.4 microg/mg) and at 8 weeks (2.40+/-1.20 versus 30.40+/-17.20 microg/mg), respectively. CONCLUSIONS: Kangaroo pericardium has a densely arranged collagen matrix with a higher extensibility and significantly lower calcification potential. Therefore, kangaroo pericardium could be used as an alternative substitute in cardiac surgery because of its low calcification potential.

Animals↗
PubMed2000

Very high Q measurements on a fused silica monolithic pendulum for use in enhanced gravity wave detectors

We present for the first time the results of very high Q factor measurements for a 2.8 kg fused silica mass suspended by two fused quartz fibers attached by a novel technique for joining fused silica or quartz. The Q for the pendulum mode at 0.93 Hz was (2.3+/-0. 2)x10(7), the highest value demonstrated to date for a mass of this size. By employing such a new suspension system the sensitivity of the gravitational wave detectors currently under construction can be increased up to 1 order of magnitude.

Journal Article↗
PubMed1998

A plant-based cholera toxin B subunit-insulin fusion protein protects against the development of autoimmune diabetes.

Oral administration of disease-specific autoantigens can prevent or delay the onset of autoimmune disease symptoms. We have generated transgenic potato plants that synthesize human insulin, a major insulin-dependent diabetes mellitus autoantigen, at levels up to 0.05% of total soluble protein. To direct delivery of plant-synthesized insulin to the gut-associated lymphoid tissues, insulin was linked to the C-terminus of the cholera toxin B subunit (CTB). Transgenic potato tubers produced 0.1% of total soluble protein as the pentameric CTB-insulin fusion, which retained GM1-ganglioside binding affinity and native antigenicity of both CTB and insulin. Nonobese diabetic mice fed transformed potato tuber tissues containing microgram amounts of the CTB-insulin fusion protein showed a substantial reduction in pancreatic islet inflammation (insulitis), and a delay in the progression of clinical diabetes. Feeding transgenic potato tissues producing insulin or CTB protein alone did not provide a significant reduction in insulitis or diabetic symptoms. The experimental results indicate that food plants are feasible production and delivery systems for immunotolerization against this T cell-mediated autoimmune disease.

Animals↗
PubMed1998

Enterococcal endocarditis--a case treated with teicoplanin and amoxycillin.

The study aimed to determine the antibacterial therapy effective in the cure of endocarditis caused by Enterococcus faecalis resistant to clinically achievable levels of vancomycin. Isolation of the causative enterococcus had been achieved by direct inoculation of the resected valve into the culture medium in theatre. The patient was known to have had an aortic valve defect since childhood and had recently undergone splenectomy following trauma. Blood cultures were negative prior to valve replacement. A perivalvular abscess was noted at operation. In vitro minimal bactericidal results and serum activity were the basis of the postoperative choice of drugs. The minimal bactericidal level of teicoplanin was 250 micrograms/ml and that of amoxycillin 64 micrograms/ml. Neither is achievable with the advocated dosage. A combination of these two cell-wall-active agents successfully eliminated the infection. Acting at two different sites in the synthesis of the bacterial cell wall, teicoplanin and amoxycillin were found to be bactericidal in vitro at the trough levels of the antibiotics in the serum. The patient recovered fully.

Adult↗
PubMed1996

Laboratory evaluation of tissue heart valves. A comparative assessment.

Tissue of commercially prepared tissue heart valves were evaluated and compared with aluminium treated, fixed porcine valve tissue in vitro (tensile strength, scanning and transmission electron microscopy) and in vivo (calcification potential after subcutaneous implantation in the rat model). Valve leaflets (n = 40) were divided into four groups according to the method of treatment: Group I (fixed in 0.652% glutaraldehyde, control), Group II (fixed and treated with aluminium), Group III (fixed and treated with Toluidine blue) and Group IV (fixed and treated with watersoluble alkyl sulphate). Tensile strength was not influenced in Group II and III (p > 0.05). Group IV indicated a significant (p < 0.05) reduction in tensile strength. Scanning electron microscopy revealed damage and loss of surface endothelium in Group III and IV respectively. Transmission electron microscopy indicated damage to underlying matricial cells in Group III and IV. Calcification potential was significantly (p < 0.001) reduced in Group II to IV. We conclude that damage ultrastructure could contribute to the reduced tensile strength in Group IV and that reduced tensile strength might have an influence on the long-term durability of tissue heart valves. Antimineralization treatment of tissue heart valves does retard calcification but is yet unable to inhibit the process completely.

Animals↗
PubMed1993

Determining locations of intracerebral lesions for proton radiotherapy.

Using an external view of the head, the ability to direct a proton radiotherapy beam at an intracerebral lesion is described, using a biostereometric (BSM) technique. The positions of markers, recognizable on computed tomography (CT) or magnetic resonance (MR) images, at known locations on the skin of a patient's head are related to the site of the lesion seen on the images. The markers' positions are determined by a BSM device, incorporating six video cameras coupled to a computer. A transformation from a coordinate system, defined by the CT or MR images, to another coordinate system, that of the BSM device, allows the proton beam to be directed towards the lesion. Markers used in this work were solid steel spheres for CT and plastic spheres containing oil for MR images.

Biomarkers↗
PubMed1989

Left ventricular myxoma. A case report.

A 27-year-old woman with a systolic ejection murmur caused by a left ventricular myxoma is described. The diagnosis of this potential fatal condition was made by echocardiography. The clinical differences between atrial and left ventricular myxoma are discussed.

Adult↗
PubMed1987

A middle ear implantable hearing device for controlled amplification of sound in the human: a preliminary report.

Millions of people in the United States suffer from hearing impairment that is not benefited or poorly benefited by surgery or conventional hearing aids. Recently, we introduced an implantable Temporal Bone Stimulator (TBS) designed for those patients having a hearing loss due to external canal conditions; such as, external canal atresia or disease, inoperable ossicular problems, atelectasis or eustachian tube malfunction, and chronic open-cavity mastoid disease. This device requires relatively good cochlear function. However, the electromagnetic application of this device has led to the development of a new device we call the Implantable Hearing Device (IHD). This device stimulates, by an electromagnetic field, an independent electromagnetic sensitive prosthesis attached to the ossicular chain. This direct energy transfer to the ossicular chain provides a high degree of sound amplification and fidelity, thus providing benefit for those with various degrees of sensorineural hearing impairment. Preliminary disclosure of the device design, the animal experimental results, and the data from human testing will be given.

Animals↗
PubMed1986

Air in the aorta: treatment by reversed perfusion.

A ventricular septal defect was repaired in a 3 1/2-year-old child on cardiopulmonary bypass. Because of excessive pulmonary venous return, a period of circulatory arrest under deep hypothermia was used. A large volume of air was found in the arterial line and the ascending aorta before perfusion was reinstituted. The air probably entered the arterial system through a large aortopulmonary collateral artery during circulatory arrest. This artery was not visualized on angiocardiography and could have caused excessive pulmonary venous return during perfusion. Air was successfully expelled by reversed perfusion. There were no neurological sequelae.

Aortic Diseases↗
PubMed1986

The surgical technique for implantation of the temporal bone stimulator (Audiant ABC).

Microsurgical techniques and modern hearing aids are very limited in providing hearing improvement to patients with a vast number of middle ear and external ear canal conditions. A new electromagnetic temporal bone stimulator (TBS), capable of direct stimulation of the cochlea, has been developed. Nothing is placed in the external ear canal. The internal portion of the device is placed in the mastoid portion of the temporal bone, thus completely bypassing the external canal, the ossicles, and the middle ear. This provides stimulation to the inner ear regardless of the condition of the external canal and the middle ear. Unilateral hearing losses may also be benefited by transfer of energy to the opposite ear. Selection of patients, the surgical technique, and the instrumental armamentarium are discussed. The pitfalls and expected results are described.

Audiometry↗