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Biomedical subjects

T Kahn

Publications and source records attributed to T Kahn.

At least 19 recordsLinked to original sources
PubMed1992

Molecular cloning, analysis, and chromosomal localization of a mouse genomic sequence related to the human papillomavirus type 18 E5 region.

The E5 open reading frame (ORF) from bovine papillomavirus type 1 (BPV 1) as well as the E5 ORFs from human papillomaviruses (HPV) type 6 and type 16 have been reported to transform immortalized rodent cells. In an analysis of murine and human tumors for the presence of putative papillomavirus-related sequences, we cloned amplified cellular sequences from the mouse cell line Eb that cross-hybridized with the E5 ORF of HPV 18. A 2.1-kb fragment termed HC1 was sequenced. In normal murine cells, it was present as a single-copy genomic sequence located on chromosome 8. A region of 213 nucleotides corresponded to the E5 gene (HC1 E5), based on the best alignments and on the presence of direct and inverted repeats bearing a central sequence motif. These structural elements are also present in the HPV 18 E5 ORF. HC1 E5 contained an ORF that was transcribed bidirectionally. The transcription in the E5 direction was enhanced in RNA obtained from organs and tumors from carcinogen-treated animals and C127 cells. The polypeptide deduced from the sequence was related to E5 proteins from genital papillomaviruses, to the putative product of the Q300 mouse gene, and to several viral and human growth factors. The data suggest that there may be several cellular counterparts to the viral E5 proteins.

Amino Acid Sequence↗
PubMed1992

Sudden loss of hearing and vestibular function, muscular weakness, and multiple white matter lesions in preschool children.

Sudden cochlear hearing loss, occurring successively or simultaneously in both ears, was observed in four unrelated preschool children. Vestibular testing could be carried out in three patients and showed complete bilateral loss of function. All patients had a mildly retarded motor development due to nonprogressive muscular weakness. On MR imaging all patients showed multiple periventricular and subcortical white matter lesions. These lesions were not clearly progressive in one patient examined repeatedly over 6 years. Virological, bacteriological, immunological, and metabolic examinations were normal in all patients. Muscle biopsy showed morphologically abnormal mitochondria in two and lipid storage in one patient. No indications have been found for a disturbed functioning of the muscle mitochondria. The identical pattern and course of the disease in these patients suggests a new nosological entity, the aetiology of which can only speculatively be attributed to a vascular process associated with a mitochondriopathy.

Biopsy↗
PubMed1992

Seroprevalence of antibodies to the human immunodeficiency virus in dialysis workers: results of a multi-center study.

The Center for Devices and Radiological Health, in collaboration with the Department of Veterans Affairs Medical Center, Brooklyn, N.Y., conducted a multi-center, multi-institutional study of the seroprevalence of antibodies to the human immunodeficiency virus (HIV) among dialysis workers. Seven dialysis units and 112 dialysis workers participated in the study over a period of 2 years. Participation was limited to dialysis workers who, by questionnaire, denied non-occupational risk factors for HIV infection. The vast majority of the study participants were drawn from areas where the prevalence of HIV infection and AIDS cases are substantially greater than the national average. Study participants received the ELISA test for HIV antibodies. All 112 of the participants tested negative for HIV antibodies. These results are encouraging, as they failed to reveal unrecognized occupational transmission of HIV infection among dialysis workers.

HIV↗
PubMed1991

Presence and integration of human papillomavirus type 6 in a tonsillar carcinoma.

Human papillomavirus type 6 subtype a (HPV-6a) was detected in a human invasive tonsillar carcinoma. Southern blot hybridization analysis showed the presence of additional bands when using non-cutting and single-cut restriction enzymes. Molecular cloning yielded two recombinant clones of 8.0 and 1.4 kb in size. The first represents the complete HPV-6a genome. Sequence analysis of the second clone showed a 0.6 kb DNA sequence corresponding to the L2 region of HPV-6a, whereas the rest belongs to cellular sequences. These data show the presence of a usually low risk HPV type in an invasive carcinoma, at an unusual infection site, with viral DNA integrated into the host genome. These findings add evidence in support of the hypothesis of a relationship between HPV infection and at least some ororespiratory cancers.

Base Sequence↗
PubMed1991

[MRT in syringomyelia--follow-up control after syringo-arachnoid shunt surgery with clinical correlation].

In 8 patients with syringomyelia, MR long-term follow-ups (observation period 25-46 months) were done after syringosubarachnoidal shunt operations. MR showed directly after surgery in 6 cases an extensive collapse of the syringomyelias and in 2 cases a lesser reduction of the diameter of the syrinx. During the subsequent course the size of the cavities increased again in 3 cases. The size of the syrinx visualised by MR did not correlate with the clinical status during the follow-up studies. This seems to point to an insufficient representation of the disease process by the morphological visualisation of the size of the syrinx.

Adult↗
PubMed1991

Accuracy of imaging modalities in staging the local extent of prostate cancer.

In this study, none of the evaluated clinical staging methods was found to predict reliably the presence or absence of extracapsular growth of histologically proved carcinoma of the prostate. In this respect, digital rectal examination, transrectal ultrasound, CT, and MR imaging cannot contribute to treatment decisions in localized prostate cancer. Further studies are under way to determine the value of 7.5-MHz scanners in transrectal ultrasound and high-resolution surface coils in MR imaging.

Biopsy↗
PubMed1990

Sulcus topography of the parietal opercular region: an anatomic and MR study.

The study describes the sulcal and gyral topography, variability, and left-right asymmetry of the parietal operculum. Eighty postmortem hemispheres as well as sagittal magnetic resonance images from 20 health volunteers (40 hemispheres) were evaluated. Four different types of parietal opercular sulcus topography were recognized. Most frequently, and conforming with the anatomic "textbook pattern", the inferior postcentral sulcus (POCS) is the sulcus anterior to the posterior ascending ramus (PAR) of the Sylvian fissure (type 1). Variations were the following: lack of a PAR (type 2), interposition of an intermediate opercular sulcus and gyrus between PAR and POCS (type 3), and direct transition of PAR into POCS with subsequent lack of a classical supramarginal gyrus (type 4). Inconstancy of the sulcal standard arrangement was especially pronounced among left hemispheres, where the patterns differed from type 1 in one third of the cases. Types 2 and 3 were significantly more frequent in left hemispheres, whereas type 4 occurred significantly more frequently in right hemispheres. Upon intraindividual left-right comparison, a remarkable 38% of the brains showed gross asymmetry of the parietal opercular sulcus patterns, characterized by a left type 2 or 3 and/or a right type 4; another 5% exhibited a reverse type of asymmetry. The findings supplement previous data on gross variability and left-right asymmetry of the posterior Sylvian fissure and its lower bank. They indicate that the Sylvian fissure is an unreliable landmark with respect to inferior parietal structures especially in left hemispheres. Individual mapping of perisylvian topography may contribute to studies on structural-functional relationship.

Adult↗
PubMed1990

Serum creatinine in patients with spinal cord injury.

In a group of 18 male patients with spinal cord injury, we found serum creatinine to be within normal limits or only minimally elevated despite significant reduction in creatinine clearance. In 8 control subjects with serum creatinine between 1.0 and 1.5 mg/dL (88.4 and 132.6 mumol/L), the measured creatinine clearance was 66.4 +/- 28.2 mL/min. In contrast, in the 5 patients with spinal cord injury whose serum creatinine was in the same range, the measured creatinine clearance was only 31.0 +/- 19 mL/min. Urinary creatinine excretion was lower in patients with spinal cord injury than in the 18 male controls (653 mg/24 hr vs. 1505 mg/24 hr). The decreased urinary creatinine could not be explained by differences in age, sex, or body weight. We calculated the relationship of creatinine clearance (Ccr) and serum creatinine (Scr) in patients with spinal cord injury to be given by the equation Ccr (mL/min) = 45/Scr (mg/dL), r = 0.73. We recommend timed urine collections for creatinine to estimate creatinine clearance accurately for clinical evaluation of patients with spinal cord injury.

Creatinine↗
PubMed1989

Infarction of intestine with massive amyloid deposition in two patients on long-term hemodialysis.

Two patients undergoing hemodialysis for 19 and 13 yr, respectively, developed intestinal infarction with extensive amyloid deposits in the muscle layer and blood vessels. In 1 patient the deposit reacted positively with antiserum to beta 2-microglobulin by immunohistochemical stain, and therefore was classified as beta 2-microglobulin in origin. The amyloid protein of the other patient remains unclassified. In patients with gastrointestinal symptoms who have been undergoing hemodialysis for long periods of time, amyloidosis of the intestine should be considered.

Amyloidosis↗
PubMed1989

[NMR tomography with gadolinium-DTPA of the trunk in pediatric oncology].

The results of enhanced MR imaging for staging, follow-up and diagnosis of recurrence are presented in 24 children with thoracic, abdominal and pelvic masses. The use of gadolinium-DTPA usually leads to better definition of the tumour and of its relation to neighbouring organs, thereby making it easier to determine whether the tumour is resectable. The place of MR imaging in the diagnostic work-up of paediatric tumours is discussed.

Abdominal Neoplasms↗
PubMed1989

[Space-occupying lesions in the pineal region--MRT using Gd-DTPA].

The results obtained from contrast-enhanced MRI in 21 patients with masses in the pineal region are reported. The use of gadolinium-DTPA results in intensive contrast uptake by the tumour; this produces better definition of the tumour and more exact delineation from neighbouring structures. This is of importance in judging resectability and in choosing the operative approach. During chemotherapy or radiotherapy, it provides reliable demonstration of the success of treatment and accurately demonstrates the size of the tumour and the presence of necrosis. On the other hand, histologic classification of pineal tumours is possible only occasionally.

Adolescent↗
PubMed1989

[Contrast medium enhanced MRT of tumors of the posterior fossa in children and adolescents].

The results of contrast-enhanced MR in 24 children and adolescents with tumours of the posterior cranial fossa are presented. During initial diagnosis, the majority of tumours showed intensive enhancement with improved demarcation from neighbouring structures. The solid component of a cystic tumour, even when small and not visible on the original scan, could be demonstrated in all cases by means of gadolinium-DTPA. Post-operatively, T2-weighted scans regularly showed areas of high signal strength at the margin of the resection; in the absence of a mass or demonstrable progression, the significance of this is uncertain. In these cases gadolinium-DTPA, because of the function of the blood-brain barrier, greatly increases accuracy in demonstrating residual or recurrent tumours.

Adolescent↗
PubMed1989

[MRT using gadolinium-DTPA in spinal intradural space-occupying lesions].

The results of contrast enhanced MRI in 36 patients with suspected spinal intradural tumours are described. All intramedullary tumors showed distinctive enhancement and solid tumors could be delineated clearly, even if they were not clearly visible on unenhanced scans. The differentiation between neoplasm and non-neoplastic syrinx was markedly improved. The sensitivity of MRI for demonstrating intradural extramedullary tumours was greatly improved by gadolinium DTPA and even small lesions or flat meningeal infiltrates could be visualised. In addition, gadolinium DTPA improved the delineation and localisation of larger lesions, even if they had already been seen on unenhanced images.

Adolescent↗
PubMed1989

Human papillomavirus type 53.

The cloning and partial characterization of the genome of human papillomavirus type 53 is presented. The virus is a distinct type and is most closely related to human papillomavirus type 30.

Cervix Uteri↗
PubMed1989

Prostatic carcinoma and benign prostatic hyperplasia: MR imaging with histopathologic correlation.

Twenty-eight patients with prostatic carcinoma who underwent magnetic resonance (MR) imaging and subsequent radical prostatectomy were studied. The resected prostates were sectioned axially, and the whole-mount prostatic specimen was compared with the corresponding MR images. The carcinoma could be identified in 20 cases (71%), but the tumor volume was underestimated in 12 patients (43%). In 19 of 20 visualized cases (95%), the carcinoma was seen as an area of low signal intensity within the peripheral zone on T2-weighted images. However, in one case the signal intensity of the carcinoma was higher than that of the remainder of the peripheral zone. All carcinomas were located within the peripheral zone. The accuracy of MR imaging in the prediction of extraglandular tumor spread was 82%, with a sensitivity of 37.5% and a specificity of 100%. Nineteen patients (67%) exhibited histologically benign hyperplasia, which could be identified on MR images in 10 cases (53%). The signal intensities of the nodules varied. All areas of benign hyperplasia were located within the central zone. The location of the pathologic changes must therefore be considered in differential diagnosis.

Adenocarcinoma↗