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Biomedical subjects

G Kohn

Publications and source records attributed to G Kohn.

At least 73 records · Page 4Linked to original sources
PubMed1978

Small marker chromosome mosaicism confirmed in two cases ascertained prenatally.

Two cases of chromosomal mosaicism were prenatally diagnosed and confirmed in tissues cultured from subsequently aborted fetuses. In both cases a small marker chromosome was observed which proved de novo in origin, since parental chromosomes were normal. The implications and interpretation of such findings in counselling families undergoing amniocenteses is discussed. Mosaicism for small marker chromosomes may be more frequent than hitherto suggested.

Adult↗
PubMed1978

Triploidy in human abortions.

Seven triploid embryos and fetuses, six spontaneously aborted and one resulting from pregnancy interruption are described. A wide range of malformations, from amorphous, nodular embryos, to apparently normal phenotypes were observed. The degree of hydatid degeneration in the placentae ranged from minimal to severe. In several cases large, atypical cells were present in the villous stroma. There was no apparent correlation between the degree of placental lesion and fetal malformations. It is suggested that termination of triploid pregnancies is determined more by the degree of placental damage rather than the severity and type of fetal anomalies.

Abnormalities, Multiple↗
PubMed1978

A new variant of mannosidosis with increased residual enzymatic activity and mild clinical manifestation.

A partial deficiency of alpha-mannosidase was found in cultured skin fibroblasts, serum, and extracts of leukoytes in two siblings with mild mental retardation, delayed speech, a suggestion of coarse or full facies, and limited mobility of the large joints. All other lysosomal enzymes tested were within the normal range. Their father demonstrated intermediate alpha-mannosidase activity. The addition of 2 mM Zn++ caused a 40% increase of the alpha-mannosidase activity in cell extracts of both patients and control subjects. pH profiles and Cellogel electrophoresis of the patients' cells indicated 20% residual activity of the acidic alpha-mannosidase isoenzyme (pH optimum at 4.0), whereas the activity of the isozyme with pH optimum of 6.0 was normal. Increasing substrate concentration (1--10 mM) demonstrated a 4 to 5-fold increase in the apparent Km of the acidic alpha-mannosidase in the patients' fibroblasts. This residual activity, however, was apparently not sufficient for the normal catabolism of mannose-containing molecules, since electron microscopic examination of the cultured fibroblasts demonstrated numerous lysosomal storage bodies.

Arylsulfatases↗
PubMed1977

Prenatal diagnosis of mucolipidosis IV by electron microscopy.

Mucolipidosis IV, a recently recognized metabolic storage disease, is characterized clinically by corneal opacity in infancy, full facial features, and psychomotor retardation. Electron microscopy of cells from a 2-year-old affected girl revealed multiple cytoplasmic storage bodies. Cultured amniotic fluid cells, in two subsequent pregnancies, demonstrated similar abnormal storage bodies. Electron microscopic examination of various uncultured tissues from one abortus demonstrated abnormal inclusions in the cells of the brain, cornea, conjunctiva, and other epithelial tissues, thus confirming the prenatal diagnosis. This suggests that mucolipidosis IV is an autosomal recessive trait and demonstrates the efficacy of electron microscopy in the prenatal diagnosis of metabolic storage diseases whose biochemical defect is yet unknown.

Amniotic Fluid↗
PubMed1977

Prenatal diagnosis and gonadal findings in X/XXX mosaicism.

Prenatal diagnosis of a case of X/XXX mosaicism is presented. In spite of the fact that over 50% of the cells cultured from both ovaries were trisomic for the X chromosome, fetal öocytes were rarely found. This case illustrates that the presence of a triple-X cell line, even in a relatively high percentage of ovarian cells, does not necessarily protect the ovary from 'aöogenesis'. This observation might prove useful in the counselling of future cases involving the prenatal detection of sex chromosome mosaicism.

Adult↗
PubMed1977

Mucopolysaccharide accumulation in cultured skin fibroblasts derived from patients with mucolipidosis IV.

Increased concentrations of total sulfated mucopolysaccharides (MPS), threefold, and hyaluronic acid (HA), 10-fold, were found in ML IV fibroblast extracts when compared to normal controls. Such accumulations altered the distribution of MPS:HA comprised 70% of total MPS in ML IV but only 30% in control cells. Intracellular sulfated MPS was observed accumulating almost linearly in ML IV fibroblasts. "Pulse-chase" experiments indicate that both HA and the sulfated MPS remain in the ML IV cells for long periods of time; in control cells, they are rapidly removed as low molecular weight, dialyzable fragments. These data suggest that the MPS accumulation in ML IV fibroblasts, is the consequence of a catabolic block, probably involving the lysosome.

Child, Preschool↗
PubMed1977

Prenatal diagnosis of genetic disease. A report on 200 amniocenteses.

The results of 200 prenatal diagnoses following amniocentesis are summarized. The routine withdrawal of 40 to 45 ml amniotic fluid caused no increase in maternal morbidity, fetal loss, prematurity or congenital malformations. There were no culture failures and in all cases in which amniotic fluid was obtained the prenatal diagnosis was subsequently confirmed. Electron microscopy was used in the prenatal diagnosis of a newly described metabolic storage disease (mucolipidosis IV). Eleven abnormal fetuses and one male fetus at risk for hemophilia A were diagnosed and aborted.

Abortion, Induced↗
PubMed1976

Achondrogenesis type I in three sibling fetuses. Scanning and transmission electron microscopic studies.

Three spontaneously aborted fetuses with Type I achondrogenesis in a family with a first cousin marriage are described. Studies by light microscopy revealed abnormal cartilage, enchondral, and periosteal bone, and normal tooth development with abnormal alveolar bone. Electron microscopic studies of cultured skin fibroblasts manifested structurally normal cells. Scanning electron microscopy studies had shown deficient intercartilaginous septa in the metaphysis, with abnormally large calcifying globules. In the diaphysis, the orientation of bone trabeculae and collagen fibers within the trabeculae was disturbed. The numerous osteocytic lucunae were wide and irregular in arrangement and shape. Type 2 achondrogenesis, as studied in these fetuses, is probably a widespread mesenchymal defect, manifested by abnormal calcification and ossification of enchondral and periosteal bone.

Achondroplasia↗
PubMed1975

Successive spontaneous abortions with diverse chromosomal aberrations in human translocation heterozygote.

A patient who had 3 first-trimester spontaneous abortions (blighted ova) was found to be carrying a balanced 13/14 Robertsonian translocation. In the 2 cases cytogenetically analyzed, different chromosomal aberration were found (trisomy 16 and supernumerary D elements). Histologic examination of the placentas of all 3 abortions revealed hypovascular or avascular villi, hydropic degeneration, and occasional atypical stromal (Hofbauer-like) cells. In 2 cases the decidua was examined by light microscopy and was diffusely inflamed with a plasmolymphocytic infiltrate. The relation of the maternal translocation to the repeated abortions with chromosome anomalies is discussed.

Abnormalities, Multiple↗
PubMed1975

Cytogenetic investigations in families with ataxia-telangiectasia.

Chromosomal studies were performed on peripheral blood lymphocytes and cultured skin fibroblasts from five Israeli-Moroccan families with ataxia-telangiectasia. A total of 24 individuals, including seven propositi, was investigated. Among the probands, significantly elevated rates of chromosome damage were observed in both blood and skin. Skin fibroblasts of affected individuals showed several orders of magnitude more chromosome breakage than lymphocytes. Increased rates of chromosome damage were also observed in the fibroblasts of some phenotypically normal family members (obligate heterozygotes and sibs) when compared to normal controls. An apparent abnormal clone of cells, possessing a large acrocentric marker chromosome (14q+), was observed in varying proportions among cells of all the propositi (2-5% of lymphocytes; 1-9% of fibroblasts).

Ataxia Telangiectasia↗
PubMed1975

On the chemical basis of chromosome banding patterns.

A comparative study of the staining characteristics of four reagents for human chromosomes has been carried out. The four reagents are: (I) quinacrine mustard, as an alkylating agent, (II) the dihydroxy derivative of quinacrine mustard, (III) quinacrine, and (IV) 9-amino-6-chloro-2-methoxyacridine. The last reagent does not possess the amino substituted side chain even though it has the same intercalating nucleus. Comparison of the first three compounds in their staining and banding behavior suggested the initial step leading to banding may be the displacement of the nucleoprotein sites in hcromosomes. The Q and G banding could be blocked experimentally by treating the chromosome preparation with dimethylamine solution. This result may suggest that these sites have weaker basic proteins (nonhistone proteins?). The use of compound IV, which does not have the side chain in the molecule but does have the same intercalating chromophore, did not lead to banding and gives indirect support to this hypothesis. A combined use of compound IV and quinacrine may be useful for the determination of total DNA vs. banding DNA.

Acridines↗
PubMed1975

De novo appearance of the ph-1 chromosome in a previously monosomic bone marrow (45,XX,-6): conversion of a myeloproliferative disorder to acute myelogenous leukemia.

Bone marrow examination of a patient with a myeloproliferative disorder revealed monosomy for chromosome No. 6 (45,XX,-6). Two months later, during blastic crisis, reinvestigation of the bone marrow showed the presence of the Ph-1 chromosome in the previously aneuploid cell line (45,XX,-6,-22,+Ph-1). This case differs from those previously published in that the Ph-1 chromosome appeared de novo during the development of frank acute myelogenous leukemia.

Adult↗
PubMed1975

An inherited translocation t(4;15) (p16;q22) leading to two cases of partial trisomy 15.

A four year old girl with severe mental retardation and multiple congenital abnormalities manifested "partial trisomy 15". Her mother, pregnant at the time of examination, possessed a balanced translocation which, after banding techniques, was identified as t(4;15)(p16;q22). Amnio-centesis revealed the karyotype of the fetus to be identical to that of the proposita and a therapeutic abortion was performed. Prenatal investigation of a subsequent pregnancy revealed a normal male karyotype. Comparison of the proposita and aborted fetus of this family with the 5 reported other cases of "partial trisomy 15" does not allow for a precise recognizable clinical syndrome.

Abnormalities, Multiple↗