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Biomedical subjects

J Mark

Publications and source records attributed to J Mark.

At least 127 records · Page 7Linked to original sources
PubMed1980

Mechanical wear of pacemaker lead insulation. A cause of loss of pacing.

A pacemaker-treated patient is described in whom lead insulation defect caused sudden loss of capture. The defect was caused by mechanical wear of the posterior leaflet of the tricuspid valve and resulted in shunting of the pulse generator with a current drain exceeding the capacity of the pacemaker. In three further cases a similar explanation to sudden loss of pacing was highly suspected.

Aged↗
PubMed1980

An established human cell line derived from a malignant mediastinal teratoma.

An established cell line derived from a human malignant mediastinal teratoma is described. The cell line was composed of slightly atypical fibroblast cells with a population-doubling time of 24 h at the exponential growth phase. The reason why the emerging cell line became fibroblastic although other tissues were present in the original tumor may be that fibroblasts so readily grow in culture. Chromosome banding showed a hypertriploid stemline number, S = 78. Almost all of the analysed karyotypes had seven markers in common. Eleven other markers, occurring at low frequency, were also detected. The origin of all markers except one could be deduced.

Adult↗
PubMed1979

Effects of amino acids on calcium uptake by glial and neuroblastoma cells.

The uptake of [45Ca] has been studied in clonal glial and neuronal cells. It was somewhat more efficient in the neuroblastoma clone M1 compared to glial clones. In all cases [45Ca] uptake was shown to depend on the phosphate concentration in the incubation medium. It was decreased by the ionophore A 23187 at 200 microM concentration in both neuronal and glial clones. The influence of amino acids some of which are putative neurotransmitters was investigated; the interactions between [45Ca] uptake and these amino acids were related to their concentration and the type of cells used (neuronal or glial). L-aspartate and taurine for example had two opposite effects on [45Ca] uptake by the glial clone NN at two different concentrations; they could therefore play a role in the control of calcium level in the synaptic cleft.

Amino Acids↗
PubMed1979

High-affinity uptake of gamma-aminobutyric acid in cultured glial and neuronal cells.

Both glial and neuronal cells maintained in primary culture were found to accumulate [3H]GABA by an efficient "high-affinity" uptake system (apparent Km = 9 muM, Vmax = 0.018 and 0.584 nmol/mg/min, respectively) which required sodium ions and was inhibited by 1 mM ouabain. Strychnine and parachloromercuriphenylsulfonate (pCS) (both at 1mM) also strongly inhibited uptake of [3H]GABA, but metabolic inhibitors (2,4-dinitrophenol, potassium cyanide, and malonate) were without effect. Only three structural analogs of GABA (nipecotate, beta-alanine, and 2,4-diaminobutyrate) inhibited uptake of [3H]GABA, while several other compounds with structural similarities to GABA (e.g. glycine, L-proline, and taurine) did not interact with the system. The kinetic studies indicated presence of a second uptake (Km = 92 muM, Vmax = 0.124 nmol/mg/min) in the primary cultures containing predominantly glioblasts. On the other hand, only one of the neuronal cell lines transformed by simian virus SV40 appeared to accumulate [3H]GABA against a concentration gradient. Apparent Km of this uptake was relatively high (819 muM), and it was only weakly inhibited by 1 mM ouabain and 1 mM pCS. The structural specificity also differed from that of the uptake observed in the primary cultures. Significantly, non of the nontransformed continuous cell lines of either tumoral (glioma, C6; neuroblastoma, M1; M1NN) or normal (NN;I6) origin actively accumulated [3H]GABA. It is suggested that for the neurochemical studies related to GABA and requiring homogeneous cell populations, the primary cultures offer a better experimental model than the continuous cell lines.

4-Chloromercuribenzenesulfonate↗
PubMed1979

Pregnancy in a non-communicating, rudimentary uterine horn. A reason for failed therapeutic second trimester abortion.

Anatomical aberrations in the female genital tract are due to maldevelopment of the Müllerian duct system. Various degrees of malformations are described (9). Some of these malformations are discovered during the investigation of amenorrhea, persistent dysmenorrhea or infertility, while others are discovered in connection with obstetrical problems. The incidence of uterine malformations is quoted as 1:1 500-2 000 (8, 11), the incidence of uterus unicollis bicornis being as rare as 1:100 000 (3). There is no unified nomenclature for the rare types of genital malformations. Semmens describes a group consisting of functional uteri of single Müllerian origin, labelled uterus unicollis bicornis with one rudimentary horn (8). Most rudimentary horns are hollow and allow the expansion of an up to 20 weeks pregnancy (3). Few cases of pregnancy in a rudimentary horn have been seen, causing complications during pregnancy and delivery, and when performing therapeutic abortions (2, 3, 4, 5, 6, 12).

Abortion, Therapeutic↗
PubMed1977

Origin of the translocated segment of the 14q+ marker in non-Burkitt lymphomas.

The cytogenetic findings by G-banding in two histiocytic lymphomas are described. Both tumors had a stemline with a 14q+ marker. The origin of the extra segment on No. 14 was determined, and it was different in the two cases. These observations, and those from non-Burkitt lymphomas with 14q+ markers reported in the literature, indicate an inconsistent pattern for the origin of the extra material on No. 14. The only feature in common for all cases is instability of the distal region of the long arm of No. 14, and liability of this region to be involved in structural rearrangements, particularly translocations.

Biopsy↗
PubMed1976

G-band analyses of a human intestinal leiomyosarcoma.

The chromosomes of a human intestinal leiomyosarcoma were studied by a direct method. The tumour had a hypodiploid stemline (S = 42) with both numerical and structural changes. These could be clarified using a G-banding method. The evolutionary pattern in the sarcoma was reminiscent of that found earlier in human meningiomas.

Aged↗