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Biomedical subjects

I Schechter

Publications and source records attributed to I Schechter.

43 records · Page 3Linked to original sources
PubMed1975

Prolonged retention of glutaraldehyde-treated skin allografts and xenografts: immunological and histological studies.

Glutaraldehyde (GA)-treated skin allografts and xenografts (from mice, rats and guinea-pigs) behave in the same way as judged from retention time, gross inspection, microscopic examination, and assays for graft antigenicity. The GA-treated grafts are retained for long periods of time (an increase by more than 6-fold as compared to untreated grafts), they are tightly bound to the recipient, they are initially soft but become progressively stiffer with minimal shrinkage in size, and remain free from infection. The histology shows that the grafts are nonviable and fixed by the GA, they are avascularized but the general structure of the skin (epidermis, adnexa and dermis) is preserved for about 3 months. The antigenicity of the GA-treated grafts is very poor, actually it is undetectable. They do not elicit the formation of cytotoxic antibodies, and animals sensitized by untreated allografts retain the GA-treated allografts similarly to normal unsensitized recipients. The lack of transplantation immunity is also indicated by the fact that GA-treated isografts behave and are rejected similarly to GA-treated allografts and xenografts. Microscopic examination suggests that the mechanism of rejection of GA-treated grafts is similar to that operating in the rejection of an inert foreign body. The marked prlongation in the retention of Ga-treated skin grafts and their properties justify investigations on the applicability of these grafts in clinical practice.

Aldehydes↗
PubMed1975

Prognostic factors in rehabilitation after severe head injury. Assessment six months after trauma.

After initial neurosurgical treatment, 40 patients who regained consciousness 1 to 90 days after major cerebral trauma, were admitted for rehabilitation. Six months after their injury they were assessed in terms of: 1) Locomotor function, 2) Intellectual performance, 3) Communication disorder, and 4) behaviour disturbances. The usefulness of these parameters as prognostic factors in rehabilitation is discussed. Eight patients without significant disabilities in all 4 parameters returned to normal life. Patients who showed locomotor, communicative and behaviour impairment but no gross intellectual deficits, were considered capable of being retrained. The poorest prospects for social and vocational rehabilitation were found in 15 patients with cognitive defects.

Adult↗
PubMedDate not supplied

Structure and function of immunoglobulin genes and immunoglobulin precursors.

To gain information on the origin of antibody diversity (somatic mutation or germ line hypothesis) it is necessary to determine the number of V region genes. For this purpose the capacity of a distinct V region probe to hybridize and quantify V genes of the same and different subgroups should be established. Relevant information on this issue was obtained from the extent of cross-hybridization of a distinct L chain cDNA with mRNAs coding for L chains of the same and different subgroups. The results indicated that: (1) V regions of similar amino acid sequence are coded by similar nucleotide sequence (this is not self-evident because of the degeneracy of the genetic code); (2) the nucleic acid probe to one V region may anneal and quantify V genes of members of the same subgroup. Molecular hybridizations of the cDNA probe with nuclear DNA showed that: (1) the number of kappa type C genes is small (about 2 per haploid genome); (2) the number of V genes presumably is also small; (3) there is no amplification of these genes in myeloma cells that produce large amounts of the Ig. These results support the somatic mutation model for the generation of antibody diversity. New information on the structure and controlled expression of Ig genes was obtained from the study of L chain precursors, which are the immediate product of L chain mRNA translation in vitro. In the precursors extra peptide segments (19-22 residues in length) precede the N-terminus of the mature L chain. Amino acid sequence analyses of the precursors provide evidence that: (1) the gene coding for the V region is larger than hitherto known; (2) duplication of a short DNA segment occurred in the structural gene coding for the MOPC-321 precursor; (3) translation of the L chain mRNA may be contingent on the nucleotide sequence coding for the extra piece; (4) cleavage of the extra piece may regulate secretion of mature L chain; (5) the extra piece is remarkably hydrophobic, suggesting that the role of the extra piece is to anchor the precursor in cell membranes, in a manner similar to the function of the "hydrophobic domain" of membrane bound proteins. We propose that most precursor molecules are directed to the endoplasmic reticulum where the extra piece is cleaved to yield mature Ig destined for secretion; a few precursor molecules escape cleavage and are anchored by means of the hydrophobic extra piece in the cell-surface membrane to serve as the antigen-recognizing receptor.

Amino Acid Sequence↗