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Biomedical subjects

A J Cohen

Publications and source records attributed to A J Cohen.

At least 19 recordsLinked to original sources
PubMed1992

Post-atherectomy coronary artery aneurysm.

A 52-year-old man underwent an uneventful directional atherectomy of the left anterior descending coronary artery. Four months after the procedure unstable angina developed and on angiogram an aneurysm of the left anterior descending coronary artery was noted. The patient underwent bypass of the left anterior descending coronary artery. An attempt to exclude the aneurysm resulted in hemodynamic compromise and was discontinued. Follow-up angiogram 2 months after operation showed the aneurysm to be smaller. The patient is doing well 6 months after operation.

Atherectomy, Coronary↗
PubMed1992

Vascular ring: does magnetic resonance imaging replace angiography?

The records of 21 patients who underwent operation for symptoms attributable to vascular ring were reviewed. The study covered 33 years, 1958 to 1991, and the mean follow-up was 6.8 years. The patients ranged from 7 days to 26 years old with a mean age of 2.9 years. Twenty patients were symptomatic. Symptoms were due to tracheal compression in 16 patients, esophageal compression in 2, and both causes in 2. During the first 30 years, chest roentgenography, barium swallow, and aortography constituted the diagnostic workup in the majority of the patients. During the last 3 years, magnetic resonance imaging replaced aortography. The surgical diagnosis included five variants of vascular ring. The surgical approach consisted of left thoracotomy in 19 patients and right thoracotomy in 2. These 2 had the diagnosis of right aortic arch with posterior left subclavian artery. In both instances, preoperative angiographic data determined the surgical approach. Barium swallow may be sufficient for the diagnosis of vascular ring; however, additional data are useful in determining the surgical approach. Magnetic resonance imaging can yield accurate data without subjecting the patient to the risks associated with angiography.

Adolescent↗
PubMed1992

The recognition, identification of morphologic substrate, and treatment of subaortic stenosis after a Fontan operation. An analysis of twelve patients.

Twelve children were identified with subaortic stenosis after Fontan's operation. All had absent resting and isoproterenol-provoked pressure gradient before the Fontan procedure. Six had a univentricular heart of left ventricular morphology, three had a single ventricle of right ventricular morphology, one had tricuspid atresia with transposition of the great arteries, one had pulmonary atresia, intact ventricular septum, and hypoplastic right ventricle, and one had corrected transposition with hypoplastic systemic ventricle. The median interval between the Fontan operation and the recognition of subaortic stenosis was 2.5 years. Ten patients underwent surgical treatment after a prior Fontan operation: Five had myectomy and enlargement of ventricular septal defect with two operative deaths; two had placement of a valved conduit from the ventricular apex to the descending aorta, and both died postoperatively; two with single ventricle had subaortic myectomy, and one had enlargement of ventricular septal defect and pulmonary aortic connection. Complete heart block developed in only one patient. Postoperative testing with Doppler echocardiography with color flow imaging demonstrated good relief of subaortic stenosis. All six children who survived the operation are well 4 months to 4 years later. Subaortic stenosis is a progressive lesion that may develop after a Fontan operation. Its surgical treatment continues to carry a significant mortality. Myectomy and enlargement of ventricular septal defect achieve direct relief of the obstruction with minimal risk of heart block.

Adolescent↗
PubMed1992

Continuous arteriovenous hemofiltration after cardiac operations in infants and children.

Acute renal insufficiency after cardiopulmonary bypass can lead to a significant morbidity from fluid overload and electrolyte disturbance, impede pulmonary gas exchange, and postpone weaning from mechanical ventilation. The limitations placed on free water intake result in severe restriction of nutrition while diuretic therapy causes electrolyte imbalance. Artificial renal support either in the form of peritoneal dialysis or hemodialysis may be complicated by sepsis and hemodynamic instability. We reviewed our experience with the use of continuous arteriovenous hemofiltration, an extracorporeal technique for removal of solutes, toxins, and water in critically ill patients with cardiac failure complicated by acute renal insufficiency and hemodynamic instability after cardiopulmonary bypass. Ten infants and children with renal insufficiency caused by low cardiac output had continuous arteriovenous hemofiltration instituted for indications including sepsis, volume overload, oliguria for more than 24 hours nonresponsive to diuretic therapy, and the need for hyperalimentation. All were supported by mechanical ventilation and receiving high-dose inotropic support. Arterial and venous vascular access was successfully obtained by cannulation of the femoral artery and vein in nine patients. Anticoagulation of the circuit was achieved with heparin infusion (6 to 20 micrograms/kg/hr) and monitored by measurement of activated clotting time. The continuous arteriovenous hemofiltration circuit was replaced if there was clot formation, or at 3 days after placement. Dialysis solution (Dianeal) 1.5% or 0.5% was infused as prefilter dilution. With the use of continuous arteriovenous hemofiltration, 20 to 100 m/hr of ultrafiltrate was removed, which allowed correction of hypervolemia, and caloric intake increased from 13.5 kcal/kg/day to 79.5 kcal/kg/day. Continuous arteriovenous hemofiltration was maintained between 5 hours and 8 days and was well tolerated in all patients. Serum urea and creatinine levels declined during continuous arteriovenous hemofiltration. We conclude that continuous arteriovenous hemofiltration is a safe and effective method for fluid and electrolyte homeostasis and that it thus allows hyperalimentation in infants and children after cardiac operations.

Acute Kidney Injury↗
PubMed1992

Sensory phenomena associated with Gilles de la Tourette's syndrome.

BACKGROUND: Our study was conducted to characterize sensory phenomena experienced by Gilles de la Tourette's syndrome (TS) sufferers. Specific foci of the study were premonitory urges associated with motor and phonic tics, site sensitization, and disinhibition behaviors. METHOD: Twenty-eight subjects were recruited for participation in the study from the Tourette's Syndrome Association and from neurologists' patient lists. All had been diagnosed as having TS at least 2 years prior to the study. Patients were contacted by telephone and questioned in an attempt to screen for participants who experienced some sensory phenomena preceding or accompanying their tics. Interviews were conducted in person with 27 of the participants and by telephone with 1 participant. RESULTS: Twenty-two (82%) of the 28 subjects experienced premonitory urges prior to motor and vocal tics. Of these 22, 13 (57%) found the premonitory urges more bothersome than the tics themselves, and 12 (55%) thought the premonitory urges enhanced their ability to suppress tics. Of 20 subjects questioned about site sensitization, 14 (70%) had heightened sensitivity to tactile, auditory, and/or visual stimuli. Disinhibition-complex behaviors the subject knows are dangerous or inappropriate but feels incapable of refraining from--was found in 10 (36%) of the 28 subjects and occurred only in subjects experiencing premonitory urges. Premonitory urges and site sensitivity can occur alone or together. Several excellent narrative descriptions of sensory phenomena associated with TS were also obtained. CONCLUSION: Much information was gained that adds to the ongoing attempt to characterize sensory phenomena associated with TS. The sensory phenomena must be understood by clinicians who treat TS sufferers, as this study shows that they add significantly to the impairment caused by TS.

Adolescent↗
PubMed1991

Tonality and perception: musical scales primed by excerpts from The Well-Tempered Clavier of J. S. Bach.

The psychological relevance of the musicians' concept of tonality was tested in the context of the music of J. S. Bach. Musically trained listeners were instructed to sing the musical scale that first came to mind immediately after hearing short excerpts from Preludes of J. S. Bach's The Well-Tempered Clavier. For each Prelude, the tonic (first note) and the mode (major or minor) of the scale produced were compared to the tonic and mode designated by Bach. Results indicated that listeners (1) often established the designated tonic and mode within the first four notes of the piece; (2) within the first four bars, often established tonalities different from that of the designated key, a tendency that increased by the eighth bar; and (3) reestablished the tonic in the last four bars. These observations validate, in general, music-theoretic assumptions about the listener's hearing of tonality, and raise issues regarding the salient relations that engage the cognitive structures underlying tonality perception.

Attention↗
PubMed1991

Perceived urgency and the anaesthetist: responses to common operating room monitor alarms.

Increasing numbers and varieties of electronic monitors are used in hospital operating rooms. Many of these are equipped with auditory alarms which are loud, insistent, or irritating, and thus are frequently disabled by the anaesthetist. This study was planned to evaluate two components of auditory alarm design which may influence the usefulness of the alarm: the perceived urgency of the auditory signal and its correlation with the urgency of the corresponding clinical situation. We also assessed the ability of practising anaesthetists to identify the monitor or condition responsible for the alarm. Sixty-four anaesthetists attending a national conference assessed ten common operating room alarm sounds for perceived urgency. Results were compared with the urgency of the corresponding clinical situation as determined by 12 senior anaesthetists. Discrepancies between the clinical and perceived urgencies of several monitor alarms were found, and there was no correlation between the two measures. The subjects were also tested for their ability to identify the alarm sounds correctly. The overall correct identification rate was 33%, and only two monitors were correctly identified by more than 50% of the subjects. The results of this study have implications for design and use of auditory alarms in hospitals and suggest the need for further research.

Adult↗
PubMed1991

Results of the Fontan procedure for patients with univentricular heart.

One hundred twenty-four consecutive patients with univentricular heart undergoing the Fontan operation were reviewed. Patients with tricuspid atresia or biventricular heart with hypoplasia of one ventricle were excluded. Eighty-four patients had left ventricular morphology. Atrioventricular connection was double-inlet (n = 76), common (n = 29), absent left atrioventricular connection (n = 14), and absent right atrioventricular connection (n = 5). Actuarial survival was 77% (70% confidence limits, 73% to 81%) at 1 year, 66% (70% confidence limits, 60% to 72%) at 5 years, and 49% (70% confidence limits, 36% to 61%) at 10 years, indicating a continuing risk for premature death. Multivariate analysis identified preoperative ventricular function and hypertrophy as risk factors for survival. High postrepair right atrial pressure (greater than 15 mm Hg) emerged as a strong intraoperative predictor of survival. Logistic regression analysis of these factors predicts high probability of death for certain subgroups of patients after the Fontan operation. Forty-four percent (n = 53) of these original 124 patients are alive and in New York Heart Association class I at follow-up. Thirty-eight percent (n = 33) of survivors have worse ventricular function than preoperative. Long-term survival is disappointing. Certain identifiable subgroups of patients with univentricular heart have unacceptable risks for the Fontan operation and should have alternate management. High postrepair right atrial pressure is an ominous sign, and if it persists the Fontan should be fenestrated or taken down.

Adolescent↗
PubMed1991

Primary cysts and tumors of the mediastinum.

A retrospective analysis was performed on 230 patients with primary cysts and tumors of the mediastinum seen at our institution from January 1944 to April 1989. We divided these patients into two groups. Group 1 was seen before 1970 and group 2 was seen from January 1970 to April 1989. There was a significant increase in the prevalence of malignancy in group 2 (47.2% versus 17.1%; p less than 0.0001) due to an increase in the number of lymphomas (22.6% versus 3.5%; p less than 0.001) and malignant neurogenic tumors (6.8% versus 1.1%; p = 0.0528). There was a significant increase in the number of malignant tumors in the anterior (59.5% versus 30.9%; p = 0.0022) and paravertebral (28.5% versus 2.8%; p = 0.0027) compartments in group 2. More patients with these tumors were symptomatic in group 2 (63.6% versus 5%; p = 0.0422). There was an increase of ancillary diagnostic studies performed to evaluate these tumors (76.0% versus 34.5%; p = 0.0422). Logistic regression analysis identified date of presentation (p less than 0.005), symptoms (p less than 0.01), size (p less than 0.005), and the anterior mediastinal compartment (p less than 0.005) as preoperative predictors of malignancy. The surgical approach to these tumors included more median sternotomy (30.1% versus 10.7%; p = 0.0008), anterior mediastinotomy, and cervical mediastinoscopy in group 2 (1.1% versus 17.5%; p = 0.0002). Long-term results support surgical resection in benign lesions and an aggressive multimodality approach to malignant lesions.

Adolescent↗
PubMed1991

Review of lead toxicology relevant to the safety assessment of lead acetate as a hair colouring.

The literature on lead toxicology has been critically reviewed to provide a safety assessment of lead acetate as a hair colouring. The main objectives were: (i) to determine the additional lead contribution from hair-colouring use to the total daily environmental lead intake; and (ii) to assess the toxicological significance of this additional contribution. The review also focuses attention on newer issues of concern over the effects of environmental lead on human health. Data available in animals and humans (including occupational exposure), mainly on lead acetate and other inorganic lead salts, have been presented and evaluated in respect of the following: absorption, distribution and excretion following ingestion; percutaneous absorption; carcinogenicity; genotoxicity; reproductive toxicity; neurological/behavioural status with particular reference to neuropsychological effects in children; and effects on other systems (e.g. cardiovascular). It is concluded that the absorption of lead from hair-colouring use represents about 0.5% of the lead absorption from the current average daily environmental lead intake. No convincing evidence could be found of any deleterious effect of current environmental lead levels on human health and thus the tiny contribution of lead acetate exposure from hair-colouring use can be regarded unequivocally as being toxicologically insignificant.

Animals↗
PubMed1991

Pyomyositis: early detection utilizing multiple imaging modalities.

Pyomyositis represents 3% to 4% of surgical admissions in East Africa, however, there were no reported cases in the United States prior to 1971. Since, there have been numerous reports of this entity. Four recent cases are presented utilizing multiple imaging modalities including magnetic resonance. MR was very sensitive to early soft tissue inflammatory processes and demonstrated these focal abscesses with superior anatomic localization. MR is advocated in the initial evaluation of a focal process. In a systemic, nonfocal process, nuclear medicine WBC or Gallium Scans to localize areas for further MR scanning is recommended.

Abdominal Muscles↗
PubMed1991

Photoprotection and 5-MOP photochemoprotection from UVR-induced DNA damage in humans: the role of skin type.

Sites on previously unexposed buttock skin in 18 subjects (skin types I-V) were treated daily for 2 weeks with suberythemogenic doses of solar-simulated radiation (SSR) alone, SSR plus a UVB sunscreen, and SSR plus the same sunscreen with 5-methoxypsoralen at 30 ppm. The three sites of treatment (designated SSR, SSR/S, and SSR/S/5-MOP), and a control site that received no SSR or topical treatment, were challenged with 2MED SSR 1 week after the treatment had ceased. Biopsy samples, taken within 15 min after the challenge dose, were assessed for unscheduled DNA synthesis (UDS, interpreted as a measure of DNA damage), melanin deposition, and stratum corneum thickening. Within a given skin type, when compared with controls, the significant increase in either pigmentation or stratum corneum thickening was similar for SSR and SSR/S/5-MOP. SSR/S inhibited these endpoints. Compared with controls, UDS was significantly reduced in skin types III-V by SSR and in all skin types by SSR/S/5-MOP. SSR/S elicited no effect apart from minimal reductions in skin types IV and V. Thus, the increases in pigmentation and stratum corneum thickening seen in all skin types with SSR and SSR/S/5-MOP were accompanied by reduced UDS in all skin types with SSR/S/5-MOP but only in skin types III-V with SSR. These findings suggest that, although induced pigmentation and stratum corneum thickening may account in part for the reduction of UDS, qualitative differences in induced pigmentation may exist in skin types I-II between SSR and SSR/S/5-MOP treatments. The findings can also be interpreted to indicate that SSR/S/5-MOP treatment can afford protection against DNA damage from subsequent exposure to solar ultraviolet radiation. Risk-benefit considerations on the use of sunscreens with and without 5-MOP are discussed and the conclusion is drawn that the judicious use of 5-MOP sunscreens, particularly in skin types I-II, affords an alternative option to those seeking a suntan.

DNA↗
PubMed1991

Role of persistent, non-genotoxic tissue damage in rodent cancer and relevance to humans.

This review has focused on the importance of cellular proliferation in neoplasia induced by nongenotoxic carcinogens and has not attempted to address the mechanisms involved in the progression from the hyperplastic to the neoplastic state. Major advances in this area are likely in the next decade and should explain how cells in an abnormally high proliferative state are rendered more vulnerable either to the action of endogenous or environmental mutagens or to defects in cell reproduction, thus providing the stimulus for progression to neoplasia (165). In this review evidence has been presented to support the hypothesis that sustained tissue damage induced by nongenotoxic compounds in rodents predisposes to tumor development. The evidence has been obtained by drawing from the published findings of experimental rodent studies conducted over the past 50 years. The experience gained at various sites in the rodent including the connective tissue, liver, bladder, and forestomach shows the existence of a threshold dose for various test materials/agents, below which neither sustained tissue damage nor tumor induction occurs but above which level both effects are manifest. Taken collectively, an overall picture emerges that sustained cell proliferation renders various sites in the rodent vulnerable to tumor development. The validity of this hypothesis is of importance to the evaluation of carcinogenic risk of chemicals to humans. For those nongenotoxic carcinogens known to cause characteristically defined and sustainable tissue damage as a precursor of tumor development in rodents, it should be possible to establish a threshold dose below which both effects disappear and upon which a safety margin in humans can be based. Some limited evidence supports an association between chronic tissue injury and neoplastic development in humans. Note, however, that certain types of induced tissue damage may be rodent-specific and therefore have no relevance for humans. We conclude that the appearance of persistent tissue damage predisposes to tumor development in rodents exposed to nongenotoxic carcinogens and that systematic studies in rodents should provide a rational basis for arriving at a safety margin in humans exposed to such agents.

Animals↗