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Y Cohen

Publications and source records attributed to Y Cohen.

At least 199 records · Page 11Linked to original sources
PubMed1993

High levels of photosystem I subunit II (PsaD) mRNA result in the accumulation of the PsaD polypeptide only in the presence of light.

The light-regulated mRNA and polypeptide accumulation of the nuclear encoded subunit II (PsaD) of the photosystem I reaction center was studied during the greening of etiolated spinach seedlings. Upon exposure to continuous white light, the mRNA, detected at low levels in etiolated seedlings, accumulated in a specific pattern. In contrast, the PsaD subunit could not be detected in the etiolated seedlings; the polypeptide could first be detected in thylakoid membranes approximately 4 h after exposure to continuous light. A pulse of red light induced the expression of the PsaD mRNA, but the polypeptide could not be detected unless the seedlings were exposed to light. In the light (but not in the dark), the PsaD mRNA was found associated with the polysomal fraction. Taken together, the data suggest a dual regulatory mechanism in which both the level of mRNA and the presence of light control the accumulation of the PsaD polypeptide.

Gene Expression Regulation↗
PubMed1993

[Tension pneumothorax from inappropriate oxygen administration].

Hospital oxygen delivery systems provide pressures of 50-55 PSI (about 4000 cm H2O). Inappropriate administration can result in severe barotrauma. Administration of O2 by face mask in an intubated patient resulted in an inadvertent connection between the oxygen and endotracheal tubes, which caused tension pneumothorax with cardiorespiratory collapse. As several such cases have been reported, we believe O2 should be administered to intubated patients only through a T-piece connection. We call for a change in the structure of O2 delivery tubes to prevent the possibility of inadvertent connection to an endotracheal tube.

Barotrauma↗
PubMed1993

[Biclonal gammopathies: clinical and theoretical aspects].

Monoclonal gammopathies are disorders in which a clone of lymphocytes arising from a common ancestor cell proliferates and secretes a monoclonal antibody. Electrophoresis of plasma proteins is used as a diagnostic test for these disorders. It produces a narrow peak within the zone of gammaglobulins, corresponding to the monoclonal antibody. On rare occasions electrophoresis produces 2 narrow peaks simultaneously, suggesting the existence of 2 monoclonal antibodies, establishing a biclonal gammopathy. We present 4 such patients with biclonal gammopathy. The prevalence of mono- and biclonal gammopathies in the general population ranges between 1-3%, but only 1% of these are biclonal. Patients with biclonal gammopathy do not differ clinically from those with monoclonal gammopathy. Theoretically, pathogenesis of biclonal gammopathies might involve true biclonicity: 2 separate transformations in 2 precursor cells. Alternatively, the 2 transformed clones might have originated from a common ancestor cell early in differentiation, prior to immunoglobulin gene rearrangement; in this case pseudobiclonicity could be implied. The question of true biclonicity versus pseudobiclonicity has been examined by others using statistical analysis of isotypic combination distributions of heavy and light chains. The incidence of identity of the light chain isotype in both monoclonal antibodies (44%) was higher than would be expected in a random distribution (27%). In a study of the 2 monoclonal immunoglobulins, the identity of the amino acid sequences of the variable site was demonstrated, suggesting a common ancestor. In another research, anti-idiotypic antibodies suggested a common idiotype in the 2 proteins. Immunofluorescent labeling of bone marrow cells produced conflicting evidence of biclonicity in several studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Update of experience with prostatic cancer].

A retrospective analysis of 302 patients with prostatic cancer, referred between 1977-1982, was updated. 15 patients (5%) with Stage A1 disease did not receive any specific treatment, and their 10-year actuarial survival was 77%. 22 (7%) had Stage A2 disease at diagnosis, 82 (27%) Stage B, 88 (29%) Stage C, and 95 (32%) Stage D. Their 10-year actuarial survival rates were 75%, 56%, 38%, and 2%, respectively. The 10-year actuarial survival of patients with well- and moderately well-differentiated adenocarcinoma was 61%, but only 13% in those with poorly differentiated adenocarcinoma (p < 0.001). A total of 116 patients with Stages A2, B and C were treated by irradiation and 71 of them also received prophylactic hormone therapy. The 10-year actuarial survival of those treated by combined irradiation and hormone therapy was 59%, compared to 19% for those treated by irradiation alone (p < 0.02). Our results emphasize the need for early diagnosis of prostatic cancer, using modern diagnostic tools such as transrectal ultrasonography and determination of prostatic specific antigen. They also prove that radiotherapy is effective and curative in a high percentage of patients with disease confined to the pelvis.

Adenocarcinoma↗
PubMed1993

Nonmagnetic hyperbaric chamber for in vivo NMR spectroscopy studies of small animals.

A description is given of the design, construction, and initial use of a polycarbonate resin hyperbaric chamber for in vivo NMR spectroscopy studies of anesthetized, ventilated rats in a horizontal bore 4.7 Tesla magnet. The chamber and its associated equipment, initially used for hyperbaric studies of rats in states of extreme hypercapnia, are also well suited for conventional hyperbaric studies, such as those related to hyperbaric oxygen therapy, oxygen toxicity, and diving. Basic technical challenges that required innovations involved: a) preservation of magnetic field homogeneity; b) avoidance of a metallic chamber body that would overload gradient and RF coils; c) physiological monitoring; and, d) remote control and stabilization of electromagnetic and physiologic factors (especially ventilatory stability) during pressure changes. A small paramagnetic bulk magnetic susceptibility shift from chamber-associated hyperbaric oxygen was observed when chamber oxygen tensions were only one atmosphere. High-quality NMR imaging and spectroscopy were demonstrated during hyperbaric conditions.

Animals↗
PubMed1993

Stable assembly of PsaE into cyanobacterial photosynthetic membranes is dependent on the presence of other accessory subunits of photosystem I.

We studied assembly of the PsaE subunit of photosystem I into photosynthetic membranes of cyanobacterial mutant strains that lack specific photosystem I subunits. Radiolabeled PsaE was incubated with photosynthetic membranes, and their binding and assembly were assayed by resistance to removal by chaotropic agents and proteolytic digestion. PsaE incorporated into the wild-type membranes was resistant to these treatments. In the absence of PsaD, it was resistant to proteolytic digestion, but was removed by NaBr. When the membranes were isolated from a mutant strain in which the psaF and psaJ genes have been inactivated, PsaE assembled in vitro could not be removed. PsaE could associate with the membranes of the strain DF in which the psaD, psaJ and psaF genes have been mutated. However, the radiolabeled PsaE associated with these membranes was removed both by the proteolytic as well as by the chaotropic agents. Characterization of PsaE present in vivo revealed similar results. These observations suggest that PsaD and PsaF/J may interact with PsaE and stabilize it in the photosystem I complex.

Blotting, Western↗
PubMed1993

Primary small noncleaved cell lymphoma of the liver. Report of an adult case in complete remission after treatment with combination chemotherapy.

Open liver biopsy in a 34-year-old woman with hepatosplenomegaly showed small noncleaved cell lymphoma. Except for an enlarged spleen, there was no evidence of other sites of involvement. She was treated with combination chemotherapy and is alive and free of disease > 5 years after diagnosis. We believe this to be the first reported case in an adult of primary hepatic or hepatosplenic lymphoma of the small cleaved cell type with long-term disease-free survival.

Adult↗
PubMed1993

Efficacy of granulocyte colony-stimulating factor and RU-40555 in combination with clarithromycin against Mycobacterium avium complex infection in C57BL/6 mice.

We compared the activities of two different biological-response modifiers with that of clarithromycin against Mycobacterium avium complex infection in C57BL/6 mice. Mice were pretreated daily with clarithromycin (50 mg/kg of body weight subcutaneously [s.c.]), RU-40555 (100 mg/kg s.c.), or granulocyte colony-stimulating factor (G-CSF) at low dose (15 micrograms/kg intraperitoneally [i.p.]) or high dose (300 micrograms/kg i.p.) 3 days before intravenous challenge with 2.5 x 10(7) CFU of the MO-1 strain of M. avium complex. Mice were treated daily until sacrifice at day 1, 8, 15, or 21 after challenge, and the numbers of CFU were measured per gram of tissue in lung and spleen. Compared at day 21 with control treatment, clarithromycin significantly decreased the level of infection in spleen (P < 0.0001) and lungs (P < 0.0001). Compared with control treatment, G-CSF at low dose had no activity, but G-CSF in combination with clarithromycin was more effective than clarithromycin alone in spleen (P < 0.05) and lungs (P < 0.015). The high dose of G-CSF was as effective as the low dose. RU-40555 alone had no beneficial activity. The RU-40555-clarithromycin combination was more effective than control treatment in spleen (P = 0.0001) and lungs (P < 0.0005) and more effective than clarithromycin alone in spleen (P < 0.009) but not in lungs. Thus, our experiments suggest that clarithromycin alone or in combination with G-CSF should be further evaluated for the prophylaxis of M. avium complex infection.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Prospective evaluation of the incidence of bacteremia after protected specimen brushing in ICU patients with and without pneumonia.

To test the hypothesis that the use of protected specimen brushing (PSB) via flexible bronchoscopy does not predispose to bacteremia in ICU patients, we prospectively performed aerobic and anaerobic blood cultures immediately following bronchoscopy with PSB. A total of 123 episodes in 68 consecutive patients with suspected pneumonia were analyzed. Blood cultures were negative in 110 cases (89 percent) and positive in 13 cases (11 percent) (p < 0.001). Twelve of these 13 patients with positive blood cultures had quantitative PSB specimen cultures showing nonsignificant growth (< 10(3) CFU/ml). In nine patients, the bacteria recovered from blood cultures (coagulase-negative staphylococci or sarcina) were considered nonpathogenic according to conventional criteria. Blood cultures grew a Staphylococcus aureus in two patients with previously documented staphylococcal septicemia. In one patient with no identifiable site of infection, the blood culture yielded Enterococcus faecalis. The only patient with both a positive blood culture and PSB culture results indicating pneumonia had different organisms recovered from the two samples. Blood cultures taken after PSB in the 17 other episodes of pneumonia (PSB specimen cultures > or = 10(3) CFU/ml) were negative. At the time of brushing and blood sampling for culture, none of these patients was receiving antibiotics active on the organisms found. In conclusion, the incidence of bacteremia after PSB in ICU patients seems very low even in patients with documented pneumonia. Substantial savings would result from not performing routine blood cultures after PSB.

Aged↗
PubMed1993

[Tumor markers].

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Animals↗
PubMed1993

[Role of 5-HT2 receptors in the positive chronotropic action of serotonin on the isolated atria in rats].

5-hydroxytryptamine (5-HT), from the concentration of 5 microM to 50 microM has a positive chronotropic activity on the rat isolated atria. The tyramine-like indirect sympathomimetic effect is the main mechanism of the 5-HT action at high concentration (50 microM). In this study, we have demonstrated that 5-HT2 receptor stimulation is also involved in the 5-HT-induced increase in atrial rate. Thus, when the tyramine-like effect was inhibited by reserpine, which causes a noradrenaline depletion of atria, the positive chronotropic effect of 5-HT (50 microM) was reduced but not abolished. The remaining response to 5-HT was completely inhibited by the 5-HT2 antagonist ketanserin (1 microM). Moreover, the increase in atrial rate induced by 5-HT, at the lower concentration of 5 microM, was fully abolished by this antagonist.

Animals↗
PubMed1993

[Primary breast lymphoma].

A 66-year-old woman with a previous diagnosis of benign histiocytosis of the right breast developed intermediate grade malignant lymphoma of her left breast 6 years later. It is suggested that the primary disease was actually a low-grade lymphoma of the MALT subgroup (mucosa-associated lymphoid tumors) which 6 years later had undergone transformation into high-grade lymphoma. This assumption is based on the known histological similarity between MALT lymphomas and benign histiocytosis.

Aged↗
PubMed1992

Assembly and processing of subunit II (PsaD) precursor in the isolated photosystem-I complex.

The precursor of photosystem I (PSI) subunit II (pre-subunit II) synthesized in vitro, was found to bind to the holo-PSI complex, both within the thylakoids and outside, after detergent extraction of PSI from the membranes. Chloroplast stromal fraction added to the purified PSI complexes, containing the labeled pre-subunit II, induced the processing of the precursor to the mature form. This implies that processing can occur within the isolated complex, after the integration of the precursor. The results presented suggest that certain aspects of biogenesis of membranal protein complexes can be studied in detergent-extracted purified complexes.

Electrophoresis, Polyacrylamide Gel↗
PubMed1992

Insertion and assembly of the precursor of subunit II into the photosystem I complex may precede its processing.

The biogenesis and assembly of subunit II of photosystem I (PSI) (psaD gene product) were studied and characterized. The precursor and the mature form were produced in vitro and incubated with intact plastids or isolated thylakoids. Following import of the precursor into isolated plastids, mostly the mature form of subunit II was found in the thylakoids. However, when the processing activity was inhibited only the precursor form was present in the membranes. The precursor was processed by a stromal peptidase and processing could occur before or after insertion of the precursor into the thylakoids. Following insertion into isolated thylakoids, both the precursor and the mature form of subunit II were confined to the PSI complex. Insertion of the mature form of subunit II was much less efficient than that of the precursor. Kinetic studies showed that the precursor was inserted into the membrane. Only at a later stage, the mature form began to accumulate. These results suggest that in vivo the precursor of subunit II is inserted and embedded in the thylakoids, as part of the PSI complex. Only later, it is processed to the mature form through the action of a stromal peptidase.

Base Sequence↗
PubMed1992

MR imaging of breast hemangioma in female infants.

Breast hemangioma in female infants is a rare benign lesion, prone to spontaneous regression. But when the lesion regresses there is a risk of breast atrophy if the breast bud is included in or very close to the hemangioma. A trial of corticosteroid therapy could be proposed to prevent this risk, but one must be sure that the breast bud is included in or very close to the hemangioma before treatment. We studied 4 children with breast hemangioma to evaluate the ability of MR Imaging in the diagnosis of breast bud inclusion. 0.5 Tesla axial Spin Echo T2-weighted images (TR = 2000 ms; TE = 120 ms) clearly depicted interface between high signal appearance of hemangioma and hypo-intensity of the breast bud: in our four patients we were able to determine whether or not the hemangioma involved the breast bud. Our preliminary study seems to demonstrate that MR imaging is a valuable imaging technique to determine which patients could be eligible for a trial of corticosteroid therapy.

Breast Neoplasms↗