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Biomedical subjects

M Cohen

Publications and source records attributed to M Cohen.

At least 361 records · Page 20Linked to original sources
PubMed1997

A new resin-reinforced glass ionomer cement for use with orthodontic attachments.

Resin cements are commonly used to bond orthodontic appliances. However, etching enamel and bracket bonding is an extremely technique-sensitive process. Moisture and saliva control, particularly in the gingival third of posterior teeth, is difficult and time-consuming, but is critical to success. Recently, a light-cure resin-reinforced glass ionomer cement was shown to perform with equal bonding capacity. This is accomplished in a wet field, without etching, and with the glass ionomer feature of fluoride release. Now, a self-cure resin-reinforced glass ionomer cement has been introduced. The self-cure cement will provide equal clinical success in areas where light curing is not possible or desired. This article compares traditional resin cements and glass ionomer cements for bonding orthodontic appliances.

Acrylic Resins↗
PubMed1996

[Giant cavernous hemangioma of the liver].

Hemangioma, the most common benign tumor of the liver, is found in 2% of all autopsies. Giant cavernous hemangiomas are those larger than 4 cm, and the only ones of clinical importance. During 1991-95 we saw 69 patients with cavernous hemangiomas of the liver ranging from 2 to 25 cm in diameter. In 62% (30 women and 13 men) they ranged from 4 to 15 cm (mean 6.3). Only 11 patients, in whom the hemangioma was symptomatic, were referred for surgery. The others were either asymptomatic or their symptoms were considered mild, and they were only followed. 4 refused surgery, but in 7 the hemangioma (ranging from 4.8 to 15.0 cm, mean 10.2) was removed; 1 required 4 units of blood. There was no mortality; complications consisted of single cases of slipped tie requiring reoperation for intraabdominal bleeding, a bile leak treated by percutaneous drainage, and delayed wound healing. After 6 months all patients were symptom-free. Our data are consistent with the present trend to operate only when a giant, cavernous hemangioma of the liver produces symptoms.

Female↗
PubMed1996

Gay, lesbian and bisexual health care issues and medical curricula.

The authors respond to Nancy Robb's account of the inadequacy of medical school curricula in addressing health care issues relevant to gay, lesbian and bisexual people (see page 765 of this issue) by proposing a framework for curriculum reform. This framework supports the development of knowledge, attitudes and skills necessary to the provision of sensitive and comprehensive care for these patient groups through four types of learning experiences: didactic instruction, small-group discussions, simulated patient encounters, and supervised encounters with real patients. Equally important is the attitudinal context in which learning takes place. Without fostering a supportive and accepting environment for education about gay, lesbian and bisexual health care issues, medical schools cannot ensure that future physicians will be equipped to provide appropriate care for all members of society.

Bisexuality↗
PubMed1996

Expression of the endogenous retrovirus ERV3 (HERV-R) during induced monocytic differentiation in the U-937 cell line.

ERV3 (HERV-R) is a complete human endogenous retrovirus located on the long arm of chromosome 7. LTR-env-gene-spliced mRNA of 9 and 3.5 Kb is widely expressed in human tissues and cells, but gag-pol mRNA has not been found. Further, the env gp70 gene contains an open reading frame throughout its length and its expression has recently been detected as a full-length protein. The highest expression of ERV3 detected so far is in placenta and the lowest in cytotrophoblasts and choriocarcinoma cell lines. In this report we have studied ERV3 mRNA and protein expression in the human monoblastic cell line U-937 during differentiation into monocytes/macrophages. Differentiation of U-937 cells was induced by 1,25a-dihydroxyvitamin D3 (vitD3), retinoic acid (RA), gamma interferon (IFN-gamma) and phorbol-myristate-acetate (PMA-TPA). The expression of ERV3 env mRNA was found to be differentiation-associated, with high expression detected in the late stages of monocytic development. Using TPA, the expression of ERV3 env was detected as 9- and 3.5-kb transcripts by Northern blotting, as mRNA by in situ hybridization and as a cytoplasmic 65-kDa protein by immunofluorescence and Western blots. Low levels of basal expression were found, with up-regulation of both message and protein at 24 to 48 hr after addition of TPA. Induction with vitD3, IFN-gamma and RA produced higher levels of mRNA at earlier time points. It is concluded that the U-937 cell line represents an excellent model system for further studies to study the relationship between ERV3 expression and cellular differentiation.

Calcitriol↗
PubMed1996

Randomized, double-blind, placebo-controlled dose-ranging study of tirofiban (MK-383) platelet IIb/IIIa blockade in high risk patients undergoing coronary angioplasty.

OBJECTIVES: The objectives of this double-blind, placebo-controlled, randomized dose-ranging study were 1) to examine the safety and tolerability of tirofiban (MK-383), a new nonpeptide platelet IIb/IIIa receptor antagonist, on a background of intravenous heparin and aspirin therapy; 2) to study the pharmacodynamics and pharmacokinetics of tirofiban; and 3) to evaluate the incidence of adverse cardiac outcomes (urgent repeat revascularization, myocardial infarction and death) with tirofiban versus placebo in a high risk subset of patients undergoing coronary angioplasty. BACKGROUND: Abrupt vessel closure complicates 4% to 8% of angioplasty procedures. Recent data have suggested that agents that antagonize the platelet glycoprotein IIb/IIIa receptor may reduce the incidence of adverse ischemic outcomes after coronary angioplasty. METHODS: Seventy-three patients received tirofiban in three sequential dose panels and 20 patients received placebo. Patients within each panel were randomized to receive either tirofiban or placebo in a 3:1 randomization design. Bolus doses of 5, 10 and 10 microg/kg and continuous infusion (16 to 24 h) doses of 0.05, 0.10 and 0.15 microg/kg per min were administered in panels I, II and III, respectively. Patients received concomitant heparin and aspirin for the angioplasty procedure. Data on patients receiving placebo (heparin and aspirin only) were pooled across panels for comparisons. The pharmacodynamic effect of tirofiban on ex vivo platelet aggregation to 5 micromol/liter adenosine diphosphate (ADP) and bleeding times were measured. Clinical outcomes were assessed in all patients, but the power to detect clinically meaningful differences (a one-third reduction in clinical events) between groups was limited (5%). RESULTS: Tirofiban was associated with a dose-dependent inhibition of ex vivo ADP-mediated platelet aggregation that was sustained during intravenous infusion and resolved rapidly after drug cessation. Adverse bleeding events, largely related to vascular access site hemorrhage, were slightly increased at the highest dose. Adverse clinical outcomes were infrequent in all patients and were not different among the small number of patients within each group. CONCLUSIONS: This study establishes a rational and generally well tolerated dosing regimen for administration of tirofiban as adjunctive therapy in high risk angioplasty patients. The impact of tirofiban on adverse clinical outcomes after angioplasty awaits definition by a larger clinical trial.

Angioplasty, Balloon, Coronary↗
PubMed1996

Reduction of high-grade spondylolisthesis using Edwards instrumentation.

STUDY DESIGN: Sixteen patients with high-grade spondylolisthesis (Grade III or higher) who underwent posterior decompression and reduction using the Edwards Modular Spine System (Spinal System Ltd., Baltimore, MD) were reviewed clinically and radiographically. OBJECTIVES: This study was undertaken to determine the efficacy of one specific reduction technique to treat patients with high-grade spondylolisthesis where there has been a loss of sagittal balance, intractable pain, and/or neurologic deficit. SUMMARY OF BACKGROUND DATA: The average age of our patients was 20 years. Preoperative slippage averaged 89%; preoperative slip angle averaged 50 degrees. Indications for surgery were back and leg pain, progression of slippage (in 9 patients), and/or the inability to stand upright with the knees straight. METHODS: Pre- and postoperative radiographic films were reviewed. The percent slip and the slip angle were measured pre- and postoperatively. Clinical data were obtained via chart review, telephone interview, and/or office visit. RESULTS: The average preoperative slip was 89%; postoperatively, the average slip was 29%. Slip angle averaged 50 degrees preoperatively and improved to a postoperative average of 24 degrees. Three patients had neurologic impairment postoperatively; one did not resolve. Four patients had hardware failure; all were revised. Ten patients had an excellent result, 5 patients had a good result, and 1 patient had a fair result. The average follow-up was 3.8 years. CONCLUSION: This procedure is technically demanding and is subject to the known risks of surgical treatment for high-grade spondylolisthesis. For select patients, it may be effective for reducing severe deformity and can be expected to afford good to excellent results. Improved sacral fixation may reduce the rate of hardware-related complications.

Adolescent↗
PubMed1996

Transcriptional activation of the Cdk inhibitor p21 by vitamin D3 leads to the induced differentiation of the myelomonocytic cell line U937.

The hormonal form of vitamin D, 1,25-dihydroxyvitamin D3, acting through its cognate nuclear receptor (vitamin D3 receptor, VDR) will induce myeloid leukemic cell lines to terminally differentiate into monocytes/macrophages. Because VDR acts by transcriptionally regulating responsive genes in a ligand-dependent manner, we sought target genes of the receptor that initiate, the differentiation process in response to ligand. We screened a cDNA library prepared from the myelomonocytic U937 cell line with probes generated from either 1,25-dihydroxyvitamin D3-treated or untreated cells. We report here that a candidate clone that hybridized differentially is the Cdk inhibitor p21WAF1, CIP1. Furthermore, we show that p21 is transcriptionally induced by 1,25-dihydroxyvitamin D3 in a VDR-dependent, but not p53-dependent, manner, and we identify a functional vitamin D response element in the p21 promoter. Transient overexpression of p21 and/or the related Cdk inhibitor p27 in U937 cells in the absence of 1,25-dihydroxyvitamin D3 results in the cell-surface expression of monocyte/macrophage-specific markers, suggesting that ligand-modulated transcriptional induction of the p21 gene facilitates the induced differentiation of this monoblastic cell line. We believe that this is the first report demonstrating that the ectopic overexpression of a Cdk inhibitor such as p21 or p27 directly leads to a terminal differentiation program.

Base Sequence↗
PubMed1996

Transluminal extraction atherectomy for aortosaphenous vein graft stent restenosis.

The optimal strategy to manage in-stent saphenous vein graft (SVG) restenosis has not been studied. We present two cases in which transluminal extraction atherectomy (TEC) was used successfully for the treatment of SVG stent restenosis. TEC atherectomy may provide an alternative to conventional balloon angioplasty for such patients.

Aged↗
PubMed1996

Plasma cell granulomas of the brain: pediatric case presentation and review of the literature.

Plasma cell granulomas (inflammatory pseudotumors) are benign inflammatory masses that have been observed in virtually every organ system but are most often described in the lung. Rare cases have been reported in which the brain and spinal cord are affected. We present the case of a 5-year-old girl with personality and behavioral changes, discovered to be harboring an intracerebral plasma cell granuloma. The literature on plasma cell granuloma of the central nervous system is discussed with emphasis on the clinical, radiological, and pathological features of these lesions.

Brain Diseases↗
PubMed1996

Diastolic or systolic left and right ventricular impairment at moderate doses of anthracycline? A 1-year follow-up study of women.

A prospective study was carried out to assess the early and later alterations in left and right ventricular diastolic and systolic function after the termination of anthracycline therapy. In 33 women without cardiac disease who were treated by anthracycline therapy, cardiac function was evaluated by radionuclide angiography before the treatment (T0) and 1 month (T1) and 12 months (T12) after the end of the treatment. Cardiac function was assessed by radionuclide measurement throughout treatment. Analysis of ejection fraction (EF), peak ejection rate (PER), time to PER (TPER), peak filling rate (PFR) and time to PFR (TPFR) was performed before and after treatment. To normalise radionuclide measurements of the ventricular diastolic function, the ratio of the PFR and the EF and the ratio of the PFR and the PER were calculated. No patient developed symptomatic congestive cardiac failure. One-way analysis of variance showed a significant decrease in the three parameters (EF, PER, PFR) over time only for the left ventricle (LV); no significant alterations appeared for the right ventricle (RV). The EF of the LV decreased from 59%+/-5% at T0 to 57%+/-6% at T1 and 56%+/-5% at T12. The PER of the LV fell from 3.03+/-0.40 end-diastolic volume per second (EDV/s) at T0 to 2.79+/-0.47 at T1 and 2.78+/-0.43 at T12. The PFR of the LV dropped from 2.99+/-0.43 EDV/s at T0 to 2.62+/-0.44 at T1 and 2.56+/-0.42 at T12. For the normalised ratios, no differences were observed. Significant differences were found for EF, PER and PFR between T0 and T1, and between T0 and T12, but no difference was found between T1 and T12. This report shows simultaneous impairment of the systolic and diastolic LV radionuclide parameters at 1 and 12 months after anthracycline therapy without alteration in the RV function.

Antibiotics, Antineoplastic↗
PubMed1996

Quantitative myocardial thallium single-photon emission computed tomography in normal women: demonstration of age-related differences.

The aim of this study is the development of a database of normal women for quantitative analysis of exercise and reinjection myocardial single-photon emission computed tomography (SPET). We studied 101 subjects (40 males and 61 females) with less than 5% likelihood of coronary artery disease. All patients underwent stress and rest thallium-201 myocardial SPET. Myocardial stress was induced by bicycle exercise test (n=51), dipyridamole infusion (n=27) or a combined test (n=23). Multivariate ANOVA showed that the type of stress did not influence the percentage of thallium uptake for each region. Significant differences between men and women were found for the percentage of uptake in the inferior and the anterior wall. The most original finding of this study is the correlation between age and thallium uptake in the three regions of the anterior wall, showing an increase in measured thallium uptake with age for women. Consequently, two groups of women, those under and those over 55 years old, were separated, with a significantly lower tracer uptake in the anterior wall in the younger age group. These results may suggest that the commonly described breast tissue attenuation is due not only to breast volume or morphology but also to breast density. This emphasizes the need for two different databases for myocardial SPET quantitative analysis in the female population. Awareness of this fact should allow avoidance of any underestimation of possible anterior wall ischaemia in women aged more than 55 years.

Adult↗
PubMed1996

Heart transplantation in patients 65 years of age and older: a comparative analysis of 40 patients.

BACKGROUND: Advanced age has traditionally been considered a relative contraindication to heart transplantation because of the potential for increased morbidity and decreased long-term survival. METHODS: We analyzed the results in 40 patients 65 years of age and older who underwent heart transplantation and compared them with those in 138 patients younger than 65 years. RESULTS: The older age group had a higher incidence of diabetes mellitus (p = 0.01), donor-recipient weight mismatch (< 0.80) (p = 0.004), lower donor-recipient weight ratio (p = 0.02), and longer allograft ischemic time (p = 0.008), among other differences. However, the 30-day operative mortality was similar in both groups (2.5% in older versus 2.2% in younger patients). Actuarial survival at 12, 24, and 36 months was not statistically different between the older and younger patients (86% +/- 6% versus 93% +/- 2%, 78% +/- 8% versus 89% +/- 3%, and 72% +/- 9% versus 81% +/- 4%, respectively; p = 0.26). The posttransplantation intensive care unit stay, total hospital stay, and associated hospital costs were also similar. The incidence of rejection during the first posttransplantation year was similar in both groups. CONCLUSIONS: Heart transplantation in selected patients 65 years of age and older can be performed successfully, with a morbidity and mortality comparable with those seen in younger patients. Advanced age should not be an exclusion criterion for heart transplantation, but selective criteria should be applied that identify risks and benefits individually.

Actuarial Analysis↗
PubMed1996

Reconstruction of complex chest wall defects.

BACKGROUND: Reconstruction of complex chest wall defects represents a major challenge and requires close cooperation between the cardiothoracic and reconstructive surgeon to achieve an optimal outcome and reduce the incidence of complications. The principles of chest wall reconstruction include control of infection, local wound care, wide debridement of all necrotic and devitalized tissues, obliteration of all residual cavities and spaces with well-vascularized tissues, reestablishment, when necessary, of the continuity and skeletal stability of the chest wall, and immediate or early definitive coverage of all defects with well-vascularized tissues. METHODS: This paper is based on our experience with 113 patients who underwent chest wall reconstruction for a variety of defects resulting from infection, trauma, tumor extirpation, and radionecrosis. All patients were treated with a variety of muscle flaps and/or omentum which provided obliteration of dead space and coverage. Seven patients with large anterolateral defects required additional skeletal stability with synthetic patches or mesh. RESULTS: 88.6% of patients healed without significant problems. 8.8% had major complications requiring reoperation and prolonged hospitalization while 4.4% had minor complications. CONCLUSIONS: Based on long-term experience, we believe that currently the use of well-vascularized tissue is the method of choice for reconstruction of complex chest wall defects. This provides stable coverage, reduces hospital stay, and thus lowers overall care cost for these patients.

Debridement↗
PubMed1996

Type II ureteral triplication associated with ectopic ureter.

We report a case of type II ureteral triplication associated with ectopic ureter. The ureter, draining the upper renal segment, entered the vagina, and the other two ureters, draining the middle and lower renal segments, had joined and entered the bladder. The anatomic findings are compatible with those predicted by the Weigert-Meyer law. A thorough evaluation of such an anomaly is essential for effective management.

Abnormalities, Multiple↗
PubMed1996

Vocational outcome of aphasic patients following severe traumatic brain injury.

The incidence and course of aphasia, and its impact on vocational outcome, were determined in a group of 351 patients with severe traumatic brain injury (TBI). Aphasia was found in 11.1%, the common forms being amnestic (56%, 22/39), expressive (10.3%, 4/39) and receptive (10.5%, 8/39), as found on the first language assessment. No age difference was found between the aphasic and non-aphasic patients. Coma was more common in the aphasics than the non-aphasics (95% and 82%, respectively), although its mean duration was shorter. Aphasics had more severe locomotor deficits (p < 0.01, Fisher test) and tended towards more severe cognitive disorders (p = 0.07, Fisher test). There was no difference between the groups in incidence of behavioural disturbances or occupational outcome. Most of the aphasic patients improved after therapy, and two recovered completely. The presence of aphasia did not have negative prognostic implications for occupational outcome.

Activities of Daily Living↗