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Biomedical subjects

H Levin

Publications and source records attributed to H Levin.

At least 19 recordsLinked to original sources
PubMed1992

Hypertension as a complication of multicystic dysplastic kidney.

The detection of multicystic dysplastic kidney in utero using prenatal ultrasound is becoming a more frequent occurrence. An accurate diagnosis of multicystic dysplastic kidney usually can be made radiographically, and therefore the main indication for surgery in the asymptomatic patient may be the potential risk of complications developing later in life. We report hypertension as a complication of multicystic dysplastic kidney and review the literature.

Child, Preschool↗
PubMed1992

Should chronic treatment-refractory akathisia be an indication for the use of clozapine in schizophrenic patients?

BACKGROUND: Clozapine, an atypical neuroleptic, is an effective medication in a subgroup of schizophrenic patients who have either failed to respond to the typical neuroleptics or experienced intolerable side effects such as neuroleptic malignant syndrome and disabling tardive dyskinesia. Its efficacy for persistent and disabling akathisia is less clear. Akathisia, especially the chronic and disabling form, can be a treatment dilemma for the clinician and the patient. METHOD: We describe three representative case illustrations of schizophrenic patients who had severe, persistent treatment-resistant akathisia. Two of them had refractory psychoses and the third had multiple disabling side effects during treatment with typical neuroleptics. Two had tardive dyskinesia. These patients were treated with clozapine while other neuroleptics were discontinued. RESULTS: During a 2-year follow-up, these patients made impressive social and vocational strides coinciding with a fairly rapid remission of akathisia (under 3 months) and a lesser though notable improvement in the psychoses. Tardive dyskinesia also remitted, though over a period of 6 to 12 months. CONCLUSION: Our experience leads us to suggest a trial of clozapine in a subgroup of schizophrenic patients, who in addition to refractory psychoses have persistent disabling akathisia. However, given the risk of agranulocytosis with clozapine, we suggest that the usual treatment strategies for akathisia be tried before clozapine is initiated in the approved manner. Future controlled trials of clozapine that specifically investigate persistent akathisia may answer this question more conclusively.

Adult↗
PubMed1990

Phase II study of homoharringtonine in patients with recurrent primary malignant central nervous system tumors.

A phase II trial of Homoharringtonine (HHT) was performed in 15 patients with recurrent or progressive malignant glioma. The drug was administered at a initial dose of 4 mg/m2/day by continuous 5 day intravenous infusion (3 mg/m2/day x 5 days for heavily pretreated patients). Courses were repeated every 3-4 weeks upon recovery from toxicity. No objective antitumor regressions occurred. Two patients had no change in their CT brain scans for 2-3 months and one patient had stable disease for 6 months. Toxicity was tolerable and included myelosuppression and occasionally mild hypotension. Chemosensitivity testing with HHT and several other chemotherapy drugs was performed in glioma cell lines, including cell lines derived from these patients. The results suggest that HHT is an inactive drug in malignant glioma using this dose schedule.

Adult↗
PubMed1988

[Diagnosis and treatment of sacral and retrorectal tumors. II].

Forty-three sacral and retrorectal tumors encountered at the Cleveland Clinic were reviewed, with emphasis on incidence, diagnosis, and management. Benign tumors could be differentiated from malignant lesions on the basis of history, physical examination, and radiologic studies. CT scan and Magnetic Resonance Imaging are the most useful tests for staging. Small benign tumors may be removed through a posterior approach. All malignant lesions, and benign lesions greater than 3-4 cm in size should be removed through a combined anterior and posterior approach. All tumors should be completely removed wherever possible, since both benign and malignant tumors will recur when excision is incomplete. Radiotherapy and chemotherapy may provide some palliation for malignant tumors, but these modalities are not curative in our experience.

Adult↗
PubMed1987

The effect of heart rate and contractility on the measurement of left ventricular mass by 201Tl SPECT.

Left ventricular myocardial mass can be measured by 201Tl SPECT, but the effects of changes in heart rate and contractility have not been determined. We constructed a dynamic computer model simulating the contracting left ventricle. Thirty two summed static views at each of 3 heart rates and 3 ejection fractions were manufactured to simulate a 180 degrees acquisition. Each image set underwent tomographic reconstruction. Left ventricular mass was measured at a fixed percent threshold in each slice. The results show that left ventricular mass varied little with heart rate (4%) and only slightly more (8%) with ejection fraction. Thus, in the normal clinical setting, left ventricular mass measurements by SPECT are minimally affected by the dynamic state of the heart.

Computer Simulation↗
PubMed1986

Aniridia, congenital glaucoma, and hydrocephalus in a male infant with ring chromosome 6.

A premature infant with unilateral aniridia and congenital ectropion uveae, contralateral Rieger anomaly, bilateral congenital glaucoma, and hydrocephalus was found to have ring chromosome 6. The findings are consistent with multiple manifestations of a neural crest-derived maldevelopment of the anterior segment and central nervous system. Comparison with the 14 previously reported cases of ring chromosome 6 illustrates the phenotypic variability of this syndrome.

Abnormalities, Multiple↗
PubMed1986

Computer modeling of planar myocardial perfusion imaging: effect of heart rate and ejection fraction on wall thickness and chamber size.

Myocardial perfusion imaging is generally performed as a static acquisition without regard for dynamic changes in the cardiac cycle. The effect of heart rate and ejection fraction on the appearance of left ventricular chamber size and wall thickness as perceived in 201Tl scintigrams has not, to our knowledge, been previously studied. A dynamic computer model of the left ventricle was constructed, capable of varying the heart rate and ejection fraction. Parallel slices through the model were convolved with experimentally derived 201Tl point spread functions at corresponding depths to incorporate the effects of scatter and attenuation. Both gated and static left anterior oblique images were created at three clinically encountered heart rates and ejection fractions, with constant end-diastolic volume and left ventricular mass. Results of the study indicate that perceived and quantified wall thickness increases and chamber size decreases appreciably with increasing ejection fraction and (slightly) with increasing heart rate. Thus, evaluation of wall thickness and chamber size in planar images should take into account variations in heart rate and contractility. This is especially pertinent to estimates of left ventricular hypertrophy and chamber size, attempted from nongated myocardial perfusion images.

Computers↗
PubMed1986

Effect of variable left ventricular vertical orientation on planar myocardial perfusion images.

Differences in vertical orientation of the left ventricle within the chest cavity cannot be corrected by gamma camera positioning. The effect of variations in vertical angulation on the appearance of the diagnostically important left anterior oblique (LAO) view has not been previously evaluated. In the current study, a computer simulation of a normal left ventricle was created and "imaged," varying only the degree of vertical rotation. The effect of six vertical positions on the LAO image was assessed visually and with horizontal and circumferential profile analysis. Results indicate a homogenous distribution of counts in the horizontal views. With increasing verticality, there are fewer counts in the valve plane, while the inferoapex initially increases in count density, and then progressively decreases. Quantification revealed count variations of up to 37% in the valve plane and 45% in the inferoapex due entirely to differences in vertical orientation of the left ventricular simulation. A survey of 167 patients who underwent routine stress thallium imaging showed a vertical angulation that varied from 7 degrees to 64 degrees (mean = 37 degrees) as determined from the anterior view. Clinical images were similar in appearance to computer generated images after correction for anterior view foreshortening. The present study suggests that the accuracy of current quantitative thallium methods to detect coronary artery disease might be enhanced by the use of a revised set of normal standards corrected for vertical orientation of the left ventricle.

Computers↗
PubMed1985

Transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation in dogs.

Elevation of intrathoracic pressure during cardiopulmonary resuscitation generates carotid pressure and flow, but also increases intracranial pressure. This increase in intracranial pressure may limit cerebral blood flow. Therefore, we performed studies designed to quantify the extent of this transmission and to identify the mechanism of transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation in dogs. Intracranial pressure increased during the chest compression phase of all modes of cardiopulmonary resuscitation tested. During simultaneous compression-ventilation cardiopulmonary resuscitation, change in intracranial pressure (mm Hg) = 0.33 change in intrathoracic pressure (mm Hg) + 2.02 (r = 0.86) and was not significantly different from the relationship observed during conventional cardiopulmonary resuscitation. The magnitude of transmission of intrathoracic pressure to the intracranial space was increased by binding the abdomen and by raising the baseline intracranial pressure. No single route accounted for transmission of intrathoracic pressure to the intracranial space during cardiopulmonary resuscitation. Intracranial pressure fluctuations were unrelated to either carotid arterial or jugular venous pressure, and were found instead to be the result of pressure transmission by blood in non-valved veins and by cerebrospinal fluid. This was determined by three maneuvers. First, obstruction of cerebrospinal fluid flow by ligation of the cervical spinal cord reduced intracranial pressure (P less than 0.001) and made the change in intracranial pressure equivalent to pressure changes at the confluence of the intracranial venous sinuses, without affecting pressure changes at the confluence of the intracranial venous sinuses. Second, ligation of the cervical spinal cord and one of the two longitudinal vertebral veins adjacent to the cervical cord reduced the pressure changes in the intracranial space and at the confluence of the intracranial venous sinuses to about 60% of the levels observed when the cervical cord alone was ligated. Thus, the non-valved longitudinal vertebral veins appear to be the vascular channels of critical importance to pressure transmission. Finally, pressure changes in the thoracic cerebrospinal fluid were increased (P less than 0.05) by cord ligation, even after exsanguination minimized pressure transmission via blood-filled channels, indicating direct transmission of intrathoracic pressure through intervertebral foramina to the cerebrospinal fluid.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1979

Impaired renal allograft function: a comparative study with angiography and histopathology.

We reviewed 47 renal transplant recipients who had undergone angiography and transplant biopsy to evaluate impaired allograft function. Angiographic criteria for rejection were seen in all allografts with hyperacute rejection, accelerated rejection and chronic rejection, and in 13 of 17 allografts with acute cellular rejection. Angiography was normal in allografts with vasomotor nephropathy or transplant glomerulopathy. Angiography is an accurate method for the diagnosis of most causes of post-transplant dysfunction.

Biopsy↗
PubMed1978

Experimental bladder substitution using a biodegradable graft of natural tissue.

A controlled canine experimental study has been performed to test the application of a biodegradeable graft to vesical augmentation. The graft, after providing initial bladder enlargement, is progressively reabsorbed while serving as a foundation for the regeneration and healing of the layers of the bladder remnant. Follow-up studies at 1 year revealed no urinary infection, calculi, extravasation of urine, or rejection of the material. Normal bladder capacities were maintained throughout the study and the reconstructed bladders functioned normally. The biodegradable graft was equally successful when applied either to a histologically normal bladder remnant, or to a pathological bladder of intramural fibrosis. These results suggest that this material may be well suited to clinical bladder substitution in humans.

Animals↗