Search PubMed⌕ Search

Biomedical subjects

M Cohen

Publications and source records attributed to M Cohen.

At least 793 records · Page 44Linked to original sources
PubMed1984

Mass-action formulations of monovalent and divalent cation adsorption by phospholipid membranes.

An extension of a previous treatment (Cohen, J. A., and M. Cohen, 1981, Biophys. J., 36:623-651) is presented for the adsorption of monovalent and divalent cations by single-component phospholipid membranes, where monovalent cations adsorb with a cation/phospholipid stoichiometry of 1:1 and divalent cations adsorb with stoichiometries of 1:1 and 1:2. Previously the 1:1 and 1:2 binding of divalent cations were assumed to occur by independent, parallel pathways. Here a serial adsorption scheme is considered in which 1:2 binding occurs via reaction of 1:1-bound complexes with adjacent unoccupied phospholipids. This two-dimensional lattice reaction is shown to obey a law of mass action, and the mass-action equilibrium constant is used to parameterize the adsorption isotherm. This isotherm is shown to be mathematically equivalent to the previous isotherm, although the two formulations differ in the dependence of 1:2 binding on the 1:1 association constant.

Cations, Divalent↗
PubMed1984

Differentiation of lymphoma from histoplasmosis in children with mediastinal masses.

The differentiation of mediastinal masses caused by lymphoma from those caused by histoplasmosis may require thoracotomy. We reviewed the medical records of 37 children undergoing initial evaluation for anterior or middle mediastinal masses. Sixteen had biopsy-proved lymphoma, and 21 had histoplasmosis; seven with histoplasmosis underwent thoracotomy. Age, sex, fever, weight loss, duration of illness, anemia, erythrocyte sedimentation rate, nonspecific reactants, and lung infiltrates and calcifications were similar in both groups. Masses were in the middle mediastinum in all patients with histoplasmosis and in 69% with lymphoma. Masses were in the anterior mediastinum in one of 21 (5%) with histoplasmosis and 13 of 16 (81%) with lymphoma. Among patients with lymphoma, histoplasmal complement fixation antibody titers were less than 1:8 in 14 of 15 (93%); a single patient had a titer of 1:16. The CF titers were greater than or equal to 1:32 in 14 of 21 (67%) with histoplasmosis. In children with middle mediastinal masses, a histoplasmal CF yeast or mycelial titer greater than or equal to 1:32 is strongly suggestive of acute histoplasmosis and biopsy is not required. Children not fulfilling these criteria should undergo diagnostic biopsy.

Adolescent↗
PubMed1984

Patency of the ductus arteriosus in normal neonates: two-dimensional echocardiography versus Doppler assessment.

Two-dimensional echocardiography using a high resolution, 7.5 ,Jsz transduce was compared with Doppler echocardiography for the assessment of patency of the ductus arteriosus in normal newborn infants. Twenty-eight neonates were studied between 1 and 10 hours (mean 5.5) after birth and both examinations were possible in 27 (96%). Doppler echocardiography under two-dimensional direction indicated ductal patency in all 27 neonates. Doppler sampling in the pulmonary end of the ductus rather than the main pulmonary artery was more sensitive for detecting patency. When two-dimensional echocardiography only was used to predict patency, there was 85% sensitivity. Two-dimensional echocardiography showed no evidence of ductus arteriosus narrowing ion four neonates studied shortly after birth. In 18, the pulmonary portion of the ductus arteriosus appeared narrowed and in 8 of these, the narrowing extended toward the mid-portion of the ductus. In five others, there was only mid-ductus arteriosus narrowing. It is concluded that high resolution two-dimensional echocardiography can be used to assess ductus arteriosus morphology, but is limited in predicting ductal patency near the time of normal physiologic closure. Combined two-dimensional and Doppler echocardiography is a highly sensitive technique for detection of ductal patency when sampling is performed in the pulmonary end of the ductus arteriosus.

Ductus Arteriosus↗
PubMed1984

Use of two-dimensional echocardiography during transseptal cardiac catheterization.

Inadvertent puncture of the intrapericardial aorta is a serious complication of transseptal catheterization. Two-dimensional echocardiography allows delineation and spatial resolution of the aorta and interatrial septum. Thirteen patients underwent transseptal catheterization with simultaneous monitoring of needle and catheter position using fluoroscopy and two-dimensional echocardiography. The interatrial septum was demonstrated in the short-axis and four chamber views, and clearly separated from the ascending aorta. The transseptal needle and catheter were visualized by echocardiography while the needle tip was manipulated into the fossa ovalis avoiding puncture of the aortic root. In some cases, under pressure from the needle tip just before puncture, the interatrial septum appears to bulge toward the left atrium. Saline solution contrast echocardiography helped to confirm the needle position in the right atrium, and in the left atrium after puncture. These data suggest that two-dimensional echocardiography is a useful adjunct to fluoroscopy during transseptal catheterization that may improve its safety and prevent complications.

Adult↗
PubMed1984

Patterns of creatine kinase release during acute myocardial infarction after nonsurgical reperfusion: comparison with conventional treatment and correlation with infarct size.

Coronary arteriography and biplane ventriculography were performed in 51 patients during the acute (mean of 6.6 hours after onset of symptoms) and chronic (1 to 3 months after admission) phase of myocardial infarction. Twenty-four patients were treated in a conventional manner. In 27 patients, reperfusion was achieved with intracoronary streptokinase after 24 +/- 20 minutes of infusion. Peak creatine kinase and cumulative creatine kinase release were derived from serial creatine kinase measurements. Ejection fraction and the length of the akinetic or dyskinetic segments were calculated in the chronic phase. The time interval between onset of symptoms and peak creatine kinase was significantly shorter for the streptokinase-treated patients as compared with the conventionally treated patients (13.5 +/- 5.3 versus 22.9 +/- 7.4 hours, p = 0.0001). Significant linear correlations were obtained for both streptokinase-treated and control patients, relating: 1) peak creatine kinase value to both length of the noncontracting segment and ejection fraction in the chronic phase, and 2) cumulative creatine kinase release to both length of the noncontracting segment and ejection fraction in the chronic phase. Patients treated with streptokinase experienced a relatively greater release of enzyme for a given infarct size as compared with those treated in a conventional manner. The difference in enzyme release between the two groups increased as infarct size increased. These observations may be explained by enhanced washout of enzyme from the infarct zone, secondary to reperfusion after intracoronary streptokinase therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Circulation↗
PubMed1984

Massive hemangioma in infants: therapeutic considerations.

Eight infants were treated for massive symptomatic hemangioma over a 6-year period. The hemangiomas were located in the liver in five infants and in the upper arm, lower leg, and face in one newborn each. Symptoms included congestive heart failure in six infants and platelet trapping in three newborns. Prednisone and surgical excision were curative in six of the eight patients, while two of the eight died of sepsis, congestive heart failure, and continued platelet trapping. Radiation therapy and arteriographic embolization were of limited value.

Combined Modality Therapy↗
PubMed1984

Human placental syncytiotrophoblastic Mr 75,000 polypeptide defined by antibodies to a synthetic peptide based on a cloned human endogenous retroviral DNA sequence.

Antibodies to a synthetic undecapeptide (NH2-Cys-Glu-Asn-Pro-Ser-Gln-Phe-Tyr-Glu-Arg-Leu-COOH), the sequence (except cysteine) of which was deduced from a previously reported cloned human retroviral gag-gene-related DNA sequence erv-1, were raised in rabbits. In immunohistochemical staining these antibodies reacted with normal human first-trimester placentas and with blighted ova and benign and malignant trophoblastic tumors (hydatidiform and destructive moles, choriocarcinomas) but not with any other normal embryonic or adult tissues tested. In all tissues the reactivity was mainly confined to cells with trophoblastic morphology. In immunoblotting the antibody detected an Mr 75,000 polypeptide in syncytiotrophoblasts isolated from first-trimester placentas and in three different lines of cultured choriocarcinoma cells. The undecapeptide blocked the reactivity of the antibody.

Antibodies↗
PubMed1984

Computed tomography of craniofacial fibrous dysplasia.

We present five patients with fibrous dysplasia: two monostotic affecting the maxilla, two craniofacial, and one disseminated. Computed tomography was extremely useful for demonstrating the gross bony changes as well as anatomical detail with preservation of the cranial exit foramina. These findings correlate with the lack of significant neurological deficits. The information obtained on CT may be useful for cosmetic reconstructive surgery and debulking procedures.

Adolescent↗
PubMed1984

Nerve staining with leucomethylene blue: an experimental study.

Identification and preservation of the facial nerve during extirpative and reconstructive surgery represents a challenge even for the experienced surgeon. We present an experimental intraoperative technique for staining the facial nerve and its branches that is safe, accurate, and inexpensive. Leucomethylene blue is injected into the precise region of the facial nerve. Staining of the surrounding tissues is efficiently reduced by irrigation with ascorbic acid solution, leaving only the facial nerve stained. This technique has been encouraging in rabbits, and with additional experience, we anticipate its use for intraoperative staining of the facial nerve in humans.

Animals↗
PubMed1984

Relationship between protein and energy in the feeding of preterm infants during the first month of life.

Energy and protein quantity and quality in the diet are factors regulating the rate of growth in the preterm infant. In the present study twenty infants 31-36 weeks of gestational age were fed with identical test formulas which varied only in the content of energy. One formula (F-81) contained 3.1 g protein (60 bovine whey: 40 bovine caseins) and 81 kcal per dl. The second formula (F-94) contained the same amount of protein but 94 kcal per dl. At an intake of 150 ml/kg/d the infants received 4.6 g protein/kg/d and either 121 or 141 kcal/kg/d. The infants on F-94 had a significantly higher rate of weight gain, but growth of length and head circumference was equal in the two groups. Significant differences were found in the plasma concentrations of glutamine and alanine between the two feeding groups. The other plasma amino acids were not statistically different in the two groups of infants. Urine excretion of threonine, serine, glycine, alanine, histidine, tyrosine, glutamine and cystathionine was significantly increased in the high caloric, F-94-group. The results indicate that increasing the caloric intake above 120 kcal/kg/d in preterm infants on a relatively high protein intake does not increase linear growth but does produce increased weight gain. The biochemical results provide indirect evidence that this weight increase is the result of increased fat accretion.

Acid-Base Equilibrium↗
PubMed1984

Immunochemical characterization of high-molecular-weight polysaccharide from Fisher immunotype 3 Pseudomonas aeruginosa.

A high-molecular-weight polysaccharide (PS) was isolated from the culture supernatant of a Fisher immunotype 3 (IT-3) strain of Pseudomonas aeruginosa. Consistent with previously reported findings for IT-1 and IT-2 PS, the preparation of IT-3 PS was found to be an immunogenic, nontoxic form of the O polysaccharide side chain on the lipopolysaccharide (LPS). The IT-3 PS was mainly carbohydrate in composition. It was serologically and chemically identical to LPS O side chain, but distinct from that structure in molecular size and immunogenicity. The IT-3 PS was nontoxic in mice and guinea pigs, nonpyrogenic in rabbits, and greater than 1,000-fold less reactive than IT-3 LPS in gelation of the Limulus amoebocyte lysate. Preliminary analyses by gas-liquid chromatography and 13C nuclear magnetic resonance have established the structural identity of IT-3 high-molecular-weight PS and the IT-3 O side chain. IT-3 PS was immunogenic in rabbits and mice. After active immunization, mice were protected against P. aeruginosa IT-3 intraperitoneal infection and burn wound sepsis. IT-3 PS also elicited protection against challenge with an IT-5 strain of P. aeruginosa, indicating that low-level contamination of the IT-3 PS with IT-3 LPS was not responsible for the immunogenic activity. These findings demonstrate the feasibility of preparing nontoxic immunogenic IT-3 PS capable of eliciting serotype-specific protective antibodies, employing methods similar to those previously described for the isolation of PS from other P. aeruginosa immunotypes.

Animals↗
PubMed1984

Implications of precordial ST segment depression during acute inferior myocardial infarction. Arteriographic and ventriculographic correlations during the acute phase.

Thirty two patients presenting with acute transmural inferior wall myocardial infarction underwent cardiac catheterisation and angiography within 12 hours of the onset symptoms. Twelve lead electrocardiograms performed within one hour of catheterisation showed ST segment depression in the anterior precordial leads in addition to inferior wall changes in 17 patients and no ST segment changes in the anterior leads in 15. When the clinical, arteriographic, and ventriculographic variables were compared between the two groups no significant differences were noted with regard to age, sex, risk factors for coronary disease, duration of symptoms before angiography, Killip class, number of inferior leads with ST segment elevation, or initial serum creatine kinase activity. The extent of coronary artery disease as well as the prevalence of severe disease in the left anterior descending artery were similar for both groups. Biplane left ventriculography showed no significant differences between the two groups with regard to global ejection fraction or to the prevalence of posterolateral or anterior segmental wall motion abnormalities.

Coronary Angiography↗
PubMed1984

Young chronic patients and changes in the state hospital population.

The number of young adult chronic patients, particularly males, has risen not only in community mental health programs but also among the inpatient populations of state hospitals. To assess the chronicity of these young adult patients, the authors divided the state hospital inpatient census into three groups based on length of stay. They found a considerable increase in the proportion of male admissions age 21 to 44 who remained hospitalized for three months or more. The three groups also differed in patient characteristics and prognosis for release. The authors conclude that the increasing number and proportion of younger patients, with their markedly different service needs, will almost inevitably alter the nature of the state hospital program for decades to come.

Adolescent↗
PubMed1984

The relationship of the peripheral leukocyte count and cigarette smoking to pulmonary function among adult men.

The relationship of the peripheral leukocyte count to pulmonary function was examined in 1,510 men. There were 466 current cigarette smokers, 485 former cigarette smokers, and 559 never smokers enrolled in a longitudinal study of aging. Spirometry was performed twice on all subjects ten years apart. A multiple regression analysis indicated that leukocyte count was inversely related to baseline levels of both forced vital capacity (FVC) (p less than 0.001) and forced expiratory volume in one second (FEV1) (p less than 0.001) after adjustment for age, height, and smoking habits. Similarly, change in leukocyte count over a ten-year period was inversely related to follow-up levels of both FVC (p = 0.036) and FEV1 (p = 0.004) after adjustment for baseline levels of leukocyte count, pulmonary function, age, height, and smoking habits. These data suggest that the peripheral leukocyte count is an important determinant of level of pulmonary function. Further investigation of the pathophysiologic mechanisms involved in this association seems indicated.

Adult↗
PubMed1984

The selective effects of central masking on brain stem potentials.

The effect of contralateral white noise stimulation on ipsilaterally presented click evoked brain stem potentials was examined. Continuous contralateral white noise does not influence the brain stem response components but pulsed white noise simultaneously presented with the clicks produced a central masking effect which was observed as an amplitude reduction confined to Wave V. Our findings confirm those of Zwislocki (1971) that pulsed noise is a more effective central masker than continuous noise. A computer addition of the responses to pulsed white noise and clicks recorded independently revealed no reduction in Wave V amplitude but the response to the two stimuli presented simultaneously showed a specific reduction in Wave V amplitude. No change in the latency of Wave V was observed to suggest any 'cross-over' masking of the click stimulus. Patients with total unilateral deafness did not exhibit this phenomenon. The effect of a time delay of the masker to one ear in relation to the click presented to the other ear reduced the amplitude of Wave V less than when the two stimuli were presented simultaneously. The reduction in the amplitude, being specific to Wave V, suggests that the effect is central and that the particular locus for this aspect of central masking is at the level of the inferior colliculus.

Audiometry↗