Search PubMed⌕ Search

Biomedical subjects

M Wallach

Publications and source records attributed to M Wallach.

At least 37 records · Page 2Linked to original sources
PubMed1986

Structure and organization of the histidine-rich protein gene of Plasmodium lophurae.

Recombinant cDNA clones representing the carboxy-terminal portion of the histidine-rich protein of Plasmodium lophurae and the 3' untranslated region of the mRNA have been sequenced. Histidine accounts for 78% of the predicted amino acid sequence. The DNA and protein sequences in this region differ significantly from published sequences deduced from cloned genomic DNA of P. lophurae. Sequence data from two independent cDNA clones, comparison of restriction endonuclease sites present in genomic DNA, genomic and cDNA clones, gene titrations, S1 nuclease digestion of cDNA-mRNA hybrids and comparison of predicted and published data for the amino acid composition of the histidine-rich protein all suggest that P. lophurae contains one histidine-rich protein gene and that the sequence of the 3' coding region of this gene has been correctly deduced from the cDNA clones.

Amino Acid Sequence↗
PubMed1985

Psychological and physical long-term effects of torture. A follow-up examination of 22 Greek persons exposed to torture 1967-1974.

After an observation period of about 10 years a follow-up examination was made of 22 Greeks earlier exposed to torture. All had physical symptoms and about 90% of the examinees had chronic psychological symptoms which had appeared after the torture experience, the most notable of which were emotional instability, depression, passivity, fatigue and disturbed sleep. Eight of the victims had a chronic organic psychosyndrome as defined by us. The clinical picture of the torture victims is very similar to other stress-conditioned syndromes, which underlines the significance of the psychological trauma for the pathogenesis. Certain physical symptoms can be related to specific forms of torture; in this series particularly, symptoms of the feet and lower extremities can be related to 'falanga' (repeated blows to the soles of the feet). The most noticeable objective finding was unilateral atrophy of testis in 2 of the examinees caused in all probability by genital torture. Treatment of the sequelae to torture should be initiated as early as possible in the course of the illness, and studies on the effect of this treatment should be carried out.

Adult↗
PubMed1984

Histidine-rich protein genes and their transcripts in Plasmodium falciparum and P. lophurae.

The presence of histidine-rich protein (HRP) related genes and gene products in Plasmodium falciparum was demonstrated using a synthetic pentahistidine-encoding oligonucleotide and a cloned HRP cDNA probe prepared from the avian parasite P. lophurae. In Northern blotting experiments, two knobby clones of P. falciparum were found to contain a 3500 nucleotide RNA species that hybridized with the oligonucleotide and HRP cDNA probes. As this component had the expected size for an mRNA encoding an 80-90 kDa protein and was absent from two knobless clones of P. falciparum, we concluded that it represented a 'knob protein' mRNA. Using the restriction enzyme EcoRI, three identical cross-hydribizing HRP gene fragments were found in the DNA of both knobby and knobless clones of P. falciparum. These fragments differed in size from those present in P. lophurae. These results suggest that the absence of knob protein mRNA in knobless clones is not due to loss of the corresponding gene(s).

Animals↗
PubMed1984

Differential expression of mRNAs for alpha- and beta-tubulin during differentiation of the parasitic protozoan Leishmania mexicana.

The parasitic protozoan Leishmania mexicana amazonensis has two developmental stages: a motile flagellated promastigote stage and a sessile intracellular amastigote stage. In our previous work, cells of the promastigote stage were found to synthesize more tubulin protein than those of the amastigote stage. Here, tubulin mRNAs in these leishmanias were analyzed. Based on dot blot hybridization between total leishmanial RNA and tubulin-specific cDNA probes derived from chicken brain, amastigotes and promastigotes were found to have approximately equal amounts of alpha- and beta-tubulin mRNAs. RNA blotting of leishmanial RNA, using chicken tubulin cDNA probes, showed that amastigotes and promastigotes both gave a single mRNA species of 2100 nucleotides for alpha-tubulin in roughly similar quantities. However, such analysis for beta-tubulin revealed mainly a single mRNA species of 3600 nucleotides for amastigotes and three species of 2800, 3600, and 4400 nucleotides for promastigotes, the smallest mRNA being the most predominant. Thus, regulation of gene expression appears to be different only for beta-tubulin between the two developmental stages of this protozoan.

Animals↗
PubMed1983

Simultaneous expression of mu- and gamma-chain mRNA in cloned murine B-lymphoma cell lines.

The expression of immunoglobulin heavy chain genes was studied in five murine B-lymphomas known from previous studies to express either mu (38C-13), mu + delta (L10A, K46, BCL1) or gamma chains (A20). The presence of mu- and gamma-mRNAs in these tumors was determined by Northern blot analyses of the total cell poly(A)+ mRNA, using the appropriate 32P-labeled recombinant plasmid probes. In four out of the five lymphomas examined, both mu- and gamma-mRNAs were detected. The mu-mRNA appeared as multiple discrete bands of 1.9-3.0 kb. In three out of the four lymphomas, the gamma-mRNA appeared as two bands, a major one of 1.9 and a minor one of 3.9 kb. Three myelomas examined by similar methods did not contain more than one class of heavy chain mRNA. Reexamination of the Ig chains produced by the B-lymphomas which expressed both mu- and gamma-mRNAs revealed that two of them preserved their original phenotype and expressed mu (38C-13) or gamma chains only (A20). In contrast, two of the cell lines previously shown to express mu but not gamma chains (i.e., L10A and K46R) had changed during growth in culture and 'switched' to the production of gamma chains only. These results indicate that, in contrast to myelomas, B-lymphomas possess two classes of mRNA. However, the production of heavy chain mRNA in B-lymphomas is not necessarily accompanied by synthesis of the corresponding polypeptide chains. More studies are necessary to find out whether the expression of 'non-productive' heavy chain mRNA molecules in B-lymphomas is related to the phenomena of 'allelic exclusion' and/or the 'heavy chain switch' which occurs during the maturation of B-cells.

Animals↗
PubMed1983

In vitro translation and characterization of a unique histidine-rich protein mRNA in the avian malaria parasite Plasmodium lophurae.

The histidine-rich protein (HRP) of the avian malaria parasite Plasmodium lophurae contains 70% histidine. It is found in dense cytoplasmic granules and during the erythrocytic cycle it accumulates to represent 10% of the dry weight of the parasite. In the present work the HRP mRNA was studied by in vitro translation and by the use of a polyhistidine oligonucleotide probe. The HRP mRNA contains 2,000-2,100 nucleotides encoding a protein with an apparent molecular weight of 50,000. In addition a HRP of molecular weight 35,000-40,000 is also produced in vitro, probably as a result of proteolytic cleavage of the molecular weight 50,000 polypeptide which corresponds to in vivo labeled and purified HRP. The HRP represents a much larger proportion of the in vitro products synthesized in the homologous cell-free system compared to the rabbit reticulocyte system, and it reflects more closely the pattern of protein synthesis seen in vivo. In addition, HRP mRNA is more abundant in polysomes isolated from young parasites than in polysomes from mature schizonts. These results indicate that the HRP accumulates as a result of amplified translation of its mRNA at certain stages of its erythrocytic cycle.

Animals↗
PubMed1983

Sequelae to genital trauma in torture victims.

Possible sequelae to genital trauma were investigated in ten male victims of torture. Two of the victims examined showed testicular atrophy. No significant difference was found in the serum concentrations of follicle-stimulating hormone, luteinizing hormone, testosterone, and prolactin in those subjected to genital torture, when compared with a control group. Serum spermatocoagglutinins were not found to be increased in either of the two groups.

Adult↗
PubMed1982

Efficient extraction and translation of Plasmodium falciparum messenger RNA.

A convenient method was employed for the efficient extraction of total RNA from Plasmodium falciparum. By depleting the total RNA of tRNA, it was shown that P. falciparum or P. lophurae tRNAs markedly stimulate the translation of P. falciparum mRNA in the rabbit reticulocyte cell-free system. Analysis of the cell-free products revealed the presence of proteins well over 200 000 molecular weight, with the majority of polypeptides having high molecular weights. Thus, this system can now be used to isolate and characterize specific mRNA molecules from P. falciparum.

Animals↗
PubMed1982

The importance of tRNA for the in vitro cell-free translation of messenger RNA isolated from the malaria parasite Plasmodium lophurae.

Preliminary studies had indicated the inadequacy of the wheat germ and rabbit reticulocyte cell-free translation systems for the in vitro translation of mRNA isolated from Plasmodium lophurae. To identify the factors which are important for the efficient translation of parasite proteins, an homologous system was established using polysomes, the pH 5 fraction, and tRNA prepared from p. lophurae. For comparison, the same components were isolated from the host duck reticulocytes and tested. The effect of each of these factors was evaluated by analysis of the translation products and by comparison with products synthetized in vivo. The results indicated that P. lophurae tRNA had a marked stimulatory effect on the synthesis of parasite proteins while it inhibited the synthesis of host proteins. Duck reticulocyte tRNA could not be used as a substitute for the parasite tRNA. Based on these findings, a commercially available rabbit reticulocyte system was supplemented with P. lophurae tRNA, which markedly increased the efficiency of translation of P. lophurae proteins by this system.

Animals↗
PubMed1980

A high production rate of translatable IgG mRNA accounts for the amplified synthesis of IgG in myeloma cells.

The aim of the present work was to determine whether the accumulation of Ig mRNA in myeloma cells is due to a high rate of production or to a high stability of these molecules. Specific mRNAs for the light and heavy polypeptide chains of IgG were isolated from the murine MPC-11 myeloma tumor cells by immune precipitation of polysomes which synthesize these chains. It was found that the immune-precipitated polysomes were enriched 10--30-fold in the gamma and chi mRNA sequences respectively. In the wheat germ cell-free system the chi mRNA preparation was translated mainly into three polypeptides of Mr 25 000, 18 000, and 15 000. The method of immune precipitation of polysomes was also used to characterize three variant clones of MPC-11 myeloma. It was found that little if any gamma-chain polysomes are present in the L-chain producer and non-producer clones, while a substantial amount of chi-chain polysomes was present in the non-producer clone. This may be due to the presence in the non-producer cells of the constant region chi-chain fragment. In order to determine the relative synthesis rate of chi and gamma mRNAs, pulse-labelled polysomes were immune precipitated using antibodies to chi and gamma chains. It was found that chi and gamma mRNA molecules are produced at a very high relative rate each accounting for 10--15% of the total labeled mRNA after 1 h of labeling. These values are higher than the steady-state pool size of chi and gamma mRNA, which was 5--6%, and indicates that the half-life of these molecules is not unusually high. It is concluded that the amplified synthesis of immunoglobulin chains in myeloma cells is mainly due to a high rate of production of translatable chi and gamma mRNAs.

Animals↗
PubMedDate not supplied

Cleidocranial dysplasia with neonatal death due to central nervous system injury in utero: case report and literature review.

Cleidocranial dysplasia (CCD), an uncommon disorder involving membranous bones, is rarely lethal in early life. The calvaria is defective and wormian bones are present. Abnormalities of the clavicles vary in severity from a minor unilateral defect to bilateral absence. This report concerns pre- and postmortem anatomical and radiological findings in a 15-day-old female neonate with CCD. Her postnatal course was characterized by seizures and recognition of hydrocephalus during the first day of life. The calvaria was hypoplastic with numerous wormian bones. A pseudofracture of the right clavicle was present. Hydrocephalus was present in the brachycephalic brain which had a severely thinned cerebral cortex. Hemosiderin in the ventricular lining and marked subependymal gliosis were interpreted as evidence of old intraventricular hemorrhage that had occurred in utero. A CCD-related condition, Yunis-Varon syndrome (YVS), is noted for early lethality and for developmental and secondary abnormalities of the central nervous system. The present case only partially matches the phenotype of YVS and might represent a part of a spectrum of phenotypic variants ranging from viable CCD to lethal YVS.

Adult↗