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Biomedical subjects

G Lund

Publications and source records attributed to G Lund.

At least 37 records · Page 2Linked to original sources
PubMed1989

Usher syndrome: clinical findings and gene localization studies.

The issue of genetic heterogeneity is a critical problem in the localization of the gene(s) for Usher syndrome. Based on the data obtained on families studied to date, the differences between type I and type II Usher syndrome appear quite distinct with regard to auditory and vestibular function. Although the majority of families can be confidently diagnosed as typical type I or type II, clinical investigations revealed four families with findings that did not fit into either of the two more common subtypes. These findings emphasize the critical importance of an in-depth clinical analysis concomitant with the linkage investigation to assure accurate subtyping of Usher syndrome. Based on an analysis of only those families with definite type I or type II Usher syndrome, approximately 17% of the genome can be excluded as a potential site of the gene for type I, and 14% can be excluded as the site for the type II gene. This study will continue until the Usher gene(s) is successfully localized.

Adolescent↗
PubMed1989

Usher syndrome: an otoneurologic study.

Usher syndrome is an autosomal recessive disorder characterized by severe hearing loss or deafness and retinitis pigmentosa. Eleven families with 25 affected members were studied. The test battery included genetic studies, clinical examination, audiological, ophthalmologic, and otoneurological tests, and magnetic resonance imaging. Sixteen affected persons had profound hearing loss or were considered anacusic, with absent bilateral vestibular responses. These patients had varying degrees of retinitis pigmentosa. These 16 patients were considered to have type I Usher syndrome. Nine persons were diagnosed as Usher type II with a moderate to profound hearing loss, normal vestibular function, and retinitis pigmentosa of varying degree. Magnetic resonance imaging was normal in all cases. Otoneurological tests indicated no central nervous system disturbances. The conclusion is that hearing loss and balance problems in Usher syndrome are due to inner ear damage with no evidence of central nervous system disturbances. Furthermore, the ataxia seen in Usher type I is due to a combination of retinitis pigmentosa and bilateral peripheral vestibular deficiency.

Adolescent↗
PubMed1989

Evaluation of magnetic resonance imaging in the diagnosis of osteonecrosis of the femoral head. Accuracy compared with radiographs, core biopsy, and intraosseous pressure measurements.

The accuracy of magnetic resonance imaging in the detection of osteonecrosis of the femoral head was compared with that of other diagnostic methods in current use: plain radiography, bone-marrow pressure determinations, intramedullary venography, and histological examination of core-biopsy bone specimens. In the first phase of the study, forty-eight patients (ninety-six hips) who were at high risk for avascular necrosis were studied. Abnormal patterns on magnetic resonance imaging, consistent with those seen in necrosis, were found in all hips that were suspected of having Ficat Stage-2 or 3 changes on the basis of radiographic evidence of the disease. Abnormal patterns on magnetic resonance imaging that were characteristic of avascular necrosis were also observed in 17 per cent of the hips that were suspected of having Ficat Stage-0 changes and in 64 per cent of those that showed Stage-1 changes, all with no radiographic changes. In the second phase of the study, twenty-three of the ninety-six hips that were suspected of having early-stage necrosis of the femoral head but showed slight or no radiographic changes were studied by repeat radiographs, Ficat functional evaluations of bone, core biopsies of the femoral head, and magnetic resonance imaging. Of the twenty-three hips, eighteen (78 per cent) had positive changes on magnetic resonance imaging; nineteen (83 per cent) had positive histological evidence of necrosis; and fourteen (61 per cent) had positive findings by bone-marrow pressure studies and intramedullary venography. Although false-negative and false-positive results were observed with magnetic resonance imaging, the over-all results of this study suggest that magnetic resonance imaging may be useful for the early diagnosis of avascular necrosis.

Adult↗
PubMed1988

MR imaging of the spine in children.

MR imaging was reviewed in 66 pediatric spinal cord patients with diagnoses of posterior fossa tumor (n = 8), primary spinal cord tumor (n = 3), metastatic disease (n = 11), neuroectodermal disorder (n = 8), congenital malformation (n = 14), trauma (n = 2), and demyelinating, neurodegenerative, or metabolic disorders (n = 9). MR proved to be useful in delineating the extent of posterior fossa and cord tumor including metastasis to the cord. MR was of limited value in demyelinating and metabolic disorders. Arnold Chiari malformations, syringomyelia, tethered cord and meningoceles were all easily evaluated using MR.

Child↗
PubMed1987

Retrieving the Amplatz retrievable vena cava filter.

The new Amplatz retrievable filter was placed 15 times into the inferior vena cava (IVC) of 7 dogs. Retrieval of the filter was attempted in 11 cases after 1 week and in 3 cases after 2 weeks. The retrieval was successful and without complication in all 14 cases. The 15th placement resulted in thrombotic occlusion of the IVC, and no retrieval was attempted.

Animals↗
PubMed1987

Exercise reduces persistent ductus arteriosus shunting in piglets.

To determine the effects of dynamic exercise on ductal left to right shunting and skeletal and myocardial blood flow distribution, a persistent ductus arteriosus was created by balloon catheters in neonatal piglets. At 8-10 weeks of age, aortic, pulmonary artery, and left atrial catheters were placed and radiolabelled microspheres injected for measuring left ventricular output, organ blood flows, and ductus left to right shunting at rest and during treadmill exercise (1.6 mph). At rest, effective left ventricular output and myocardial and skeletal muscle blood flows were similar in the study group and controls. Exercise increased skeletal muscle and left ventricular blood flows similarly in the control and study group and did not accentuate the exercise induced small reduction in the left ventricular subendocardial to subepicardial blood flow ratio. This was due to a significant reduction in the ductus left to right shunt during exercise (mean(SD) 34(15) vs 18(7)%, p less than 0.02) and maintenance of effective left ventricular output in the study group (447(144) vs 446(98) ml.min-1.kg-1 in controls). The reduction in ductus shunting during exercise was due to a significant decrease in systemic vascular resistance and a small increase in pulmonary vascular and ductus resistance. Thus, reduced persistent ductus arteriosus shunting and maintenance of effective left ventricular output prevents myocardial perfusion abnormalities during dynamic exercise in swine with a persistent ductus and small to moderate left to right shunts.

Animals↗
PubMed1987

Prostatic urethra: experimental dilation in dogs.

An animal study was undertaken to develop a balloon dilation technique that could be used in humans to treat the common ailment of benign prostatic hypertrophy. Dogs were used as a model because of the similarities in the prostate between the two species and the ready availability of the canines. A retrograde transurethral approach was used for dilation. Balloon catheters, 8-20 mm in diameter, were used. Significant, long-lasting dilatation of the prostatic urethra was not accomplished until 20-mm balloons (or two 10-mm ones) inflated for 10 minutes were used. The animals were followed for up to 14 months. No deleterious histologic effects of dilation were identified within the urethra or prostate that could lead to stenosis of the prostatic urethra in later stages.

Animals↗
PubMed1987

Benign prostatic hypertrophy: retrograde transurethral dilation of the prostatic urethra in humans. Work in progress.

Retrograde transurethral balloon dilation of the prostatic urethra was performed in five human volunteers with benign prostatic hypertrophy. Each patient underwent cystoscopy, uroflow studies, voiding cystourethrography, retrograde urethrography, and magnetic resonance imaging before dilation and at defined intervals afterward. The longest follow-up to date is 8 months. Patients were given topical anesthetics and mild sedatives, and dilation was performed with a 25-mm urethroplasty balloon catheter inflated at 3-6 atm for 10 minutes. All catheter manipulations were done with a guide wire and under fluoroscopic control. Significant resolution of symptoms of prostatism was seen in four patients. The unsatisfactory results in the last patient were believed to be caused by ineffectual dilation of predominantly middle lobe hypertrophy--a condition that is now regarded as a contraindication to dilation. This technique has promise to replace transurethral resection of the prostate as the treatment of choice for this common male ailment.

Aged↗
PubMed1987

MRI in organ transplantation.

Experience with MRI in transplant patients is limited. The normal transplant kidney is characterized by a sharply defined corticomedullary border on T1 weighted images. Loss of CMC is seen in transplant rejection and in some patients with ATN. Presence of CMC does not rule out rejection, however. The spectrum of changes in cyclosporine toxicity is unclear, as only a few patients have been reported. For heart, liver, and pancreas transplantation magnetic resonance spectroscopy and imaging may prove useful in the evaluation of organ viability preoperatively and in early detection of rejection. Carefully designed prospective studies are needed to better define the role of MRI in organ transplantation.

Graft Rejection↗
PubMed1987

Immunological findings during an acute relapse of subacute sclerosing panencephalitis in a patient with an unusually prolonged disease course.

A 171/2-year-old male subacute sclerosing panencephalitis patient underwent a disease relapse after an 8 year remission. A total of 14 paired peripheral blood/cerebrospinal fluid specimens were obtained during this relapse. These specimens were tested for 13 parameters of non-specific or measles virus-specific cell-mediated and humoral immunity. There was a rapid and significant fluctuation in all of these tests. Total loss of measles-specific T cells response was found during the relapse. The response re-appeared and measles-specific antibodies increased significantly later on. The results suggest that measles virus infection was reactivated in this patient and that the observed immunological changes could at least partially be explained by this.

Adolescent↗
PubMed1986

Circulating immune complexes in patients with subacute sclerosing panencephalitis.

Levels of immune complexes (ICs) in serum and cerebrospinal fluid (CSF) specimens from subacute sclerosing panencephalitis (SSPE) patients were measured using a solid-phase C1q radioimmunoassay. Single or serial serum specimens were available from 19 patients, while serial CSF specimens were available from two patients. ICs isolated from one CSF specimen by C1q immobilized to Affi-Gel were analyzed for measles virus antigens by binding of measles virus-specific antisera and by polyacrylamide gel electrophoresis followed by Western blotting. Of 78 serum specimens analyzed, 36 (46%) were positive for ICs. When the 8 patients with 3 or more serum specimens were analyzed, 6 had fluctuating levels of ICs. Two of 5 CSF specimens obtained from a patient during acute disease onset were IC-positive, while a second patient exhibited a rapid increase and decrease of IC levels in 14 CSF specimens obtained during an acute disease exacerbation. Composition analysis of ICs isolated from one of the CSF specimens revealed the presence of antigens corresponding in size to measles virus polymerase, nucleoprotein, and possibly, hemagglutinin polypeptides. These results show that SSPE patients frequently have ICs, that IC levels fluctuate in both serum and CSF, and that the ICs are at least partially composed of measles virus antigens.

Antigen-Antibody Complex↗
PubMed1986

Experience with the Amplatz retrievable vena caval filter. Work in progress.

The Amplatz retrievable vena caval filter was designed in an attempt to decrease complications associated with the placement of Mobin-Uddin or Kimray-Greenfield filters. The design allows percutaneous retrieval, thus expanding application of the filter to situations requiring temporary prophylaxis against pulmonary embolism. Filters have been placed in 16 patients, nine (56%) for prophylactic purposes. All filters were easily inserted percutaneously. Complications occurred in three patients; these included complete thrombosis of the inferior vena cava below the filter, misplacement of one filter into the pericaval retroperitoneal tissue, and development of thrombus cranial to the filter. With the current introduction system, the possibility of filter misplacement has been essentially eliminated. No patient experienced symptoms suggestive of pulmonary embolism after filter insertion. One filter retrieval has been performed, with no complications.

Adult↗
PubMed1986

MR evaluation of the portal vein in pediatric liver transplant candidates.

Nine pediatric liver transplant candidates underwent preoperative MR evaluation of the portal vein and the inferior vena cava. Sonographic correlation was available in all patients and angiographic correlation was available in five. Pathologic correlation was obtained in seven cases either at liver transplantation or autopsy. MR demonstrated portal vein patency in three cases when it was not seen by angiography and confirmed portal vein patency in one patient when it was questionably identified on sonography. The portal vein was not seen on MR imaging in two cases when it was seen on sonography and angiography: in one case, it was small and to-and-fro flow was demonstrated angiographically; in the second case, the portal vein was occluded by tumor thrombus. Two vessels in two patients were misidentified by sonography and identified correctly by MR. These were an azygous continuation of the inferior vena cava and a large collateral vein in the portal region. Knowledge of the anatomy and documentation of vascular patency are essential in evaluation of patients before liver transplantation. In patients with complex anatomy or hemodynamics, it may be necessary to obtain this information from several imaging techniques (sonography, angiography, and MR).

Child, Preschool↗