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Biomedical subjects

M Kunin

Publications and source records attributed to M Kunin.

13 recordsLinked to original sources
PubMed2002

Conservative treatment of prosthetic valve endocarditis due to Mycobacterium fortuitum.

Described here is the case of a patient with infective endocarditis in a prosthetic valve due to a Mycobacterium fortuitum-group organism. The patient was treated medically and had a favorable clinical response. This is only the second report of survival after Mycobacterium fortuitum-group endocarditis, and the first of survival without surgical intervention. The duration of treatment is not well defined for this patient, but life-long suppressive therapy will likely be required.

Aged↗
PubMed2001

Cell transformation induced by hepatitis C virus NS3 serine protease.

Persistent infection with hepatitis C virus (HCV) may lead to hepatocellular carcinoma (HCC). It has been suggested that HCV-encoded proteins are directly involved in the tumorigenic process. The HCV nonstructural protein NS3 has been identified as a virus-encoded serine protease. To study whether HCV NS3 has oncogenic activity, nontumorigenic rat fibroblast (RF) cells were stably transfected with an expression vector containing cDNA for the NS3 serine protease (nucleotides 3356-4080). The NS3 serine protease activity was determined in the transfected cells. The transfected cells grew rapidly and proliferated serum independently, lost contact inhibition, grew anchorage independently in soft agar and induced significant tumour formation in nude mice. Cells transfected with an expression vector containing a mutated NS3 serine protease (serine 139 to alanine at the catalytic site) showed no transforming abilities; their growth was dependent on serum and they did not grow anchorage independently in soft agar. Moreover, cells transfected with the NS3 serine protease and treated with the chymotrypsin inhibitors TPCK and PMSF (a serine protease inhibitor) lost their transforming feature. These results suggest that the NS3 serine protease of HCV is involved in cell transformation and that the ability to transform requires an active enzyme.

Animals↗
PubMed2000

Role of muscle pulleys in producing eye position-dependence in the angular vestibuloocular reflex: a model-based study.

It is well established that the head and eye velocity axes do not always align during compensatory vestibular slow phases. It has been shown that the eye velocity axis systematically tilts away from the head velocity axis in a manner that is dependent on eye-in-head position. The mechanisms responsible for producing these axis tilts are unclear. In this model-based study, we aimed to determine whether muscle pulleys could be involved in bringing about these phenomena. The model presented incorporates semicircular canals, central vestibular pathways, and an ocular motor plant with pulleys. The pulleys were modeled so that they brought about a rotation of the torque axes of the extraocular muscles that was a fraction of the angle of eye deviation from primary position. The degree to which the pulleys rotated the torque axes was altered by means of a pulley coefficient. Model input was head velocity and initial eye position data from passive and active yaw head impulses with fixation at 0 degrees, 20 degrees up and 20 degrees down, obtained from a previous experiment. The optimal pulley coefficient required to fit the data was determined by calculating the mean square error between data and model predictions of torsional eye velocity. For active head impulses, the optimal pulley coefficient varied considerably between subjects. The median optimal pulley coefficient was found to be 0.5, the pulley coefficient required for producing saccades that perfectly obey Listing's law when using a two-dimensional saccadic pulse signal. The model predicted the direction of the axis tilts observed in response to passive head impulses from 50 ms after onset. During passive head impulses, the median optimal pulley coefficient was found to be 0.21, when roll gain was fixed at 0.7. The model did not accurately predict the alignment of the eye and head velocity axes that was observed early in the response to passive head impulses. We found that this alignment could be well predicted if the roll gain of the angular vestibuloocular reflex was modified during the initial period of the response, while pulley coefficient was maintained at 0.5. Hence a roll gain modification allows stabilization of the retinal image without requiring a change in the pulley effect. Our results therefore indicate that the eye position-dependent velocity axis tilts could arise due to the effects of the pulleys and that a roll gain modification in the central vestibular structures may be responsible for countering the pulley effect.

Computer Simulation↗
PubMed1999

Mesalamine-induced granulomatous hepatitis.

A 42-yr-old man with ulcerative colitis was admitted for investigation of prolonged fever associated with cholestatic liver tests. Endoscopic retrograde cholangiopancreatography demonstrated a normal biliary tree, and liver biopsy showed granulomata. A clinical diagnosis of drug-induced granulomatous hepatitis was established as the symptoms disappeared after cessation of mesalamine therapy and recurred on rechallenge. Although the differential diagnosis of fever and hepatitis in patients with inflammatory bowel disease is wide, in this case mesalamine is the most likely cause.

Adult↗
PubMed1997

Vibration reduces thermal pain in adjacent dermatomes.

Spatial summation of thermal pain crosses dermatomal boundaries. In this study we examined whether a vibrational stimulus applied to adjacent or remote dermatomes affects thermal pain perception to the volar forearm. Contact heat at 2 degrees C above thermal pain threshold was applied, and a Visual Analog Scale (VAS) was used for pain assessment. We found a significant decrease in mean VAS rating when simultaneous vibratory stimuli were given to the dermatome adjacent to that receiving thermal stimulation, or to the same dermatome on the contralateral side. There was no change in VAS rating when vibration was given two or more dermatomes away. Vibration within the same dermatome also did not yield a significant change in VAS rating, possibly due to difficulty in magnitude assessment of stimuli given simultaneously within a single dermatome. The finding that vibration can reduce pain across dermatomes may allow for more flexible design of stimulation therapy for pain.

Adolescent↗
PubMed1990

The encased ureter: bullet and bodkin pattern, a reliable radiographic sign.

Among the causes of constricted ureter is benign or malignant encasement. The diagnosis of ureteric encasement is frequently overlooked, even by well informed clinicians and radiologists. The most common benign cause is retroperitoneal fibrosis and the most frequent malignant causes are extension from an adjacent primary tumour, true metastases to the ureter and lymphoma. Lack of recognition of the process may lead to mistaken diagnosis of an inflammatory stricture or infiltrating transitional cell tumour, with resultant inappropriate management. A sign which appears to be almost specific for encasement, the bullet and bodkin configuration, is described here. Newer imaging modalities such as computed tomography and ultrasound, while helpful, are probably less sensitive and less specific than the retrograde ureterogram because a detectable mass is not always present.

Humans↗
PubMed1988

Visual contrast enhancement with a patterned overlay.

A dot-screen pattern was devised and superimposed on computed tomography images to improve contrast at a viewbox. The phenomenon is believed to be probably related to lateral inhibition. To evaluate its usefulness, the device was used on 12 images (eight showed metastatic liver lesions, and four were normal); each image was viewed without the device by ten observers. Three control images were viewed a second time without the device. The remaining nine images were viewed a second time with the device. The overlay improved diagnostic performance in nine observers. Sensitivity improved by 12%, and confidence in true-positive findings increased by 41.6%. Forty-five percent of false-negative findings were converted to true positive with the use of the overlay.

Humans↗
PubMed1986

Bridging septa of the perinephric space: anatomic, pathologic, and diagnostic considerations.

The perinephric space is not a simple fat-filled chamber through which fluid may be distributed unhindered. It is divided into multiple compartments by fibrous lamellae, the bridging septa. Some of these structures arise from the renal capsule and extend to the perinephric fascia; others are attached only to the renal capsule and are arranged more or less parallel to the renal surface. Still others connect the anterior to the posterior leaves of the perinephric fascia. The resulting compartments exert an important influence on pathologic processes, resulting, for example, in limitation of the spread of pus and tamponade of bleeding points. The configuration of many perinephric collections can only be understood by knowledge of the existence and arrangement of these lamellae. The current criteria for differentiation of subcapsular from perinephric hematomas are shown to be in error, and a new sign for such differentiation is described. There are also implications regarding therapeutic drainage of perinephric abscesses, particularly by the percutaneous route. A new classification of the perinephric fascia is proposed.

Abscess↗
PubMed1984

Concentric folds in the bladder: a new sign of chronic outlet obstruction and neurogenic bladder.

The finding of concentric folds in the bladder on excretory urography is a hitherto unreported but reliable sign of chronic urinary retention, usually due to outlet obstruction or neurogenic bladder. In a study of 152 consecutive patients with urinary retention, the presence of typical concentric folds alone was found to be as common and, therefore, as sensitive an indicator as trabeculation. The sign is useful in evaluating the significance of the incompletely emptied bladder on the post-void film, and in detecting unsuspected disease. A false-positive rate of 1.5% was found in a control series of 190 women, and no false-positive findings were seen in 214 men concurrently studied. A hypothesis concerning the mechanism of concentric fold formation is advanced.

Chronic Disease↗