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Biomedical subjects

J Fleck

Publications and source records attributed to J Fleck.

At least 37 records · Page 2Linked to original sources
PubMed1991

Genes encoding the small subunit of RUBISCO belong to two highly conserved subfamilies in Nicotianeae.

The sequences of seven complementary DNAs or genes encoding the small subunit (SSU) of ribulose-1,5-bisphosphate carboxylase oxygenase (RUBISCO) in several Nicotianeae were examined. Two new SSU genes isolated from Nicotiana sylvestris were included. Both sequence comparisons and Southern analyses with specific probes reveal that SSU genes fall into two homogeneous subfamilies that are highly conserved in Nicotianeae and are also present in other Solanaceae. Additional criteria such as number of introns and level of expression fitted to this classification. Homogeneity must have been maintained by gene conversion and/or an unusually high fidelity of DNA replication, whereas traces of slippage-stranded DNA mispairing and/or transposition probably explain local changes. Taken as a whole, these results show that the divergence between the two subfamilies predated the divergence between genera inside the Solanaceae, but that Nicotianeae retained the most simple SSU gene family structure.

Base Sequence↗
PubMed1990

Is ubiquitin involved in the dedifferentiation of higher plant cells?

Transformation of a mesophyll cell into a viable protoplast that is able to re-enter the cell cycle, divide and further differentiate into organs, is accompanied by a very rapid and important increase in ubiquitin gene expression. Three major size classes of ubiquitin mRNA transcripts were observed in protoplasts as soon as they were isolated and incubated in their culture medium. The 1.6 kb mRNAs were expressed in response to the stress caused by the isolation procedure. They decreased after a few hours of incubation in the culture medium. The 1.9 kb and the 1.3 kb mRNAs enhanced in protoplasts were also observed in young leaves and in actively dividing cells: they appeared to be developmental-stage specific. They are not expressed in response to the stress, but may be considered to be part of the dedifferentiation program induced in protoplasts. These results suggest, as the enhancement of ubiquitin gene expression coincides with the dramatic changes in gene expression observed in protoplasts, that ubiquitin may play a fundamental role in the process of cellular dedifferentiation.

Blotting, Northern↗
PubMed1989

Colony formation from mesophyll protoplasts of a cereal, oat.

Differentiated leaf cells of gramineous plants, among them the cereals with their immense importance for human nutrition, are considered extremely recalcitrant to, if not incapable of, reentering the cell cycle. This recalcitrance is related to the poor wound response of the monocots-in contrast to most dicots-and the difficulties encountered in monocot tissue culture. We report here the highly reproducible induction of sustained divisions at high frequency (up to 95%) and colony formation from mesophyll protoplasts of a cereal, oat, demonstrating that-contrary to most earlier evidence-mesophyll cells of a gramineous plant have not irreversibly lost their potential for cell division.

Journal Article↗
PubMed1988

Group therapy with Southeast Asian refugees.

This report describes a one-year experience with a new program of group therapy for Southeast Asians who were treated in a psychiatric program for Indochinese refugees. Cultural factors involving communication styles, respect for authority, and traditional social relationships greatly influence the group process. Socialization experiences which encouraged traditional activities and practical information were the most acceptable medium by all the groups. Psychological issues of losses, cultural conflicts, and persistent discussion of somatic symptoms were voiced throughout the activities. Formal group psychotherapy was periodically useful in some groups. Flexibility, meeting concrete needs, keeping a bicultural focus, and maintaining the individual therapy sessions contributed to the acceptance by the patient.

Acculturation↗
PubMed1987

Absence of some truncated genes in the amphidiploid Nicotiana tabacum.

As an initial step towards understanding how a multigene family evolves after an interspecific hybridization and subsequent chromosomal doubling, genomic Southern blots of three related species were compared: Nicotiana tabacum (the progeny), and Nicotiana sylvestris and Nicotiana tomentosiformis (the progenitors). Genomic restriction fragments generated by two endonucleases were hybridized with a cDNA of the small subunit of ribulose bisphosphate carboxylase from N. sylvestris. The restriction pattern of the DNA of the progenitors revealed considerable polymorphism of restriction-fragment lengths. All the fragments in N. tabacum, except one, have a corresponding fragment in one of the progenitors. Some fragments present in the parents were absent from the progeny: they may correspond to truncated genes consisting of only part of the 3' portion of the gene.

DNA Restriction Enzymes↗
PubMed1987

Antidepressant blood levels in Southeast Asians. Clinical and cultural implications.

After long-term treatment with tricyclic antidepressants (TCA), the TCA blood levels of 41 depressed Southeast Asian patients were determined by high-pressure liquid chromatography. No detectable medicine level was found in 25 (61%) of the patients and a therapeutic level by American standards was found in only six (15%), indicating a high incidence of noncompliance. A Cambodian subgroup, however, was significantly more compliant than either the Vietnamese or Mein patients. After patient education and a discussion of problems and benefits of medicine, compliance improved with Vietnamese and Cambodians but not with the Mien. Cultural and educational factors influence compliance with medicine and responsiveness to education. Because the Cambodians also suffered from posttraumatic stress disorder, it is probable that the presence of this illness increased compliance. Preliminary data among these patients indicate that Asians probably need the same dose of imipramine as Americans to achieve a "therapeutic" level. Reports that Asians need lower doses of TCA medicine are limited by the high noncompliance rates with Asians. These high rates probably reflect cultural beliefs about illness and medication usage. It is valuable to perform TCA blood levels on Asian patients for whom antidepressants have been prescribed to monitor compliance and to lead into a discussion of benefits and side effects of the medicine. Evidence of noncompliance can lead to a productive doctor-patient discussion about beliefs and effects of the medication.

Adult↗
PubMed1987

Psychotherapy with severely traumatized refugees.

Severely traumatized refugees often have a complicated and chronic clinical course involving a posttraumatic stress disorder. The diagnosis and therapy of such patients faces many problems. Based upon observations of chronic posttraumatic stress disorder in refugees of many countries, the authors suggest treatment approaches.

Adult↗
PubMed1985

One-year follow-up study of posttraumatic stress disorder among survivors of Cambodian concentration camps.

One year after receiving a diagnosis of posttraumatic stress disorder, five of 12 Cambodian concentration camp survivors who entered a treatment program no longer met the diagnostic criteria for the disorder, and symptoms in three others had improved. The intrusive symptoms of nightmares, sleep disorders, and startle reactions showed the most consistent improvement. Avoidance behavior, shame, and caring for others improved the least. The authors advocate use of tricyclic antidepressant medication and a consistent, supportive long-term psychotherapeutic commitment in treating this severely traumatized group.

Adult↗
PubMed1984

Posttraumatic stress disorder among survivors of Cambodian concentration camps.

Thirteen Cambodian refugees who had survived 2-4 years of concentration camp experience met the DSM-III criteria for posttraumatic stress disorder. Their predominant symptoms were avoidance, hyperactive startle reactions, emotional numbness, intrusive thoughts, and nightmares, which had lasted at least 3 years after the imprisonment. The patients' avoidance of thoughts or discussion of the past and the shame they felt about Cambodia's history made diagnosis and treatment difficult. These findings give cross-cultural validation to the diagnosis of posttraumatic stress disorder and should alert clinicians to its existence in a population not previously studied.

Adult↗
PubMed1982

Expression of the gene coding for the small subunit of ribulosebisphosphate carboxylase during differentiation of tobacco plant protoplasts.

A hybridization probe was used to study the regulation of expression of the gene coding for the small subunit of ribulose 1,5-bisphosphate carboxylase, during functional differentiation of protoplasts. A library of cDNA from poly(A)-containing RNA extracted from specially treated tobacco leaves was constructed in the plasmid pBR322 by blunt-end ligation. This library was screened by colony hybridization with 32P-labelled cDNA prepared from mRNA coding for the precursor of the small subunit. A positive colony was identified containing recombinant plasmids with a nucleotide sequence homologous to this mRNA. These plasmids, bound to diazobenzyloxymethylated cellulose paper, were then used as a hybridization probe. The results showed unambiguously that the small subunit was not transcribed in protoplasts but was transcribed in undifferentiated white and chlorophyll-containing green callus cultures derived from protoplasts. The discrepancy between these results and those obtained with classical techniques is discussed.

Carboxy-Lyases↗
PubMed1976

[Bacterial adjuvants in cell mediated immunity. Recent data].

Only some bacterial adjuvants are able to stimulate cell-mediated immunity. It has been shown recently that this property is due to a cell-wall component, the peptidoglycan. The relevance of these findings to tumor immunity has been discussed.

Adjuvants, Immunologic↗
PubMed1975

[Effect of pH on bacteria in early log phase].

The bacteria harvested in the early log phase lyse when they are submitted to a pH above 10. The peptidoglycan is not degraded in these conditions. Thus, the authors used these properties to extract the peptidoglycan from several gram negative and gram positive bacteria.

Bacillus megaterium↗
PubMed1975

Adjuvant activity of bacterial peptidoglycans.

Purified peptidoglycans isolated from various Gram negative and Gram positive bacteria can substitute for Mycobacteria in Freund's adjuvant. Monomeric subunits possess the same adjuvant activity. This activity seems to be related to the peptidic fraction.

Adjuvants, Immunologic↗
PubMed1975

Mitogenic effect of bacterial peptidoglycans possessing adjuvant activity.

Two purified peptides extracted from E. coli or B. megaterium strongly stimulated the spleen lymphocytes of rabbits and of normal or nude mice. Both preparations can substitute for Mycobacteria in Freund's complete adjuvant. The peptidoglycan extracted from M. lysodeikticus by a similar procedure which lacks adjuvant activity, did not induce blast transformation. However, the monomere of the E. coli peptidoglycan was devoid of mitogenicity although it has also a marked adjuvant activity.

Adjuvants, Immunologic↗