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Biomedical subjects

I Nielsen

Publications and source records attributed to I Nielsen.

96 records · Page 6Linked to original sources
PubMedDate not supplied

Changes in intracellular magnesium concentrations during cisplatin chemotherapy.

Magnesium is mainly an intracellular cation, and its availability is not represented reliably by plasma levels. The effects of cisplatin on Mg concentrations in plasma (PMg) and erythrocytes (EMg) were investigated in 22 neoplastic patients. Assays were done before and 1, 2, 4 and 7 days after cisplatin administration; 10 patients were also checked following six courses of chemotherapy. PMg decreased progressively either day by day after a single dose of cisplatin (p < 0.001 on the 7th day) or month by month after cumulative doses (p < 0.05 after two courses and p < 0.001 after six). EMg decreased till the 4th day (p < 0.001), but recovered pretreatment levels on the 7th day; an actual depletion was manifested only after the third course of chemotherapy (p < 0.05) and became more marked after the 6th. These results suggest that, besides renal Mg wasting, Mg metabolism is influenced by cisplatin also at a cellular level. The cisplatin-induced injury on membrane transport systems, where Mg is abundant and plays an important stabilizing role, might induce an early shift of Mg from cells into the blood stream. When repair systems begin to act, Mg is taken up from plasma to recover the normal cellular content. The lack of an actual depletion of Mg body stores till the third course of chemotherapy possibly makes the early Mg supplementation commonly administered before or contemporaneously to cisplatin infusion unnecessary. Oral supplements between the courses might be sufficient to prevent Mg depletion without exposing the patients to the risk of hypermagnesemia in case of cisplatin-induced acute renal failure.

Adult↗
PubMedDate not supplied

[Changes in blood iron levels during cisplatin chemotherapy. Preliminary results].

Iron levels during cisplatin chemotherapy were evaluated in 23 neoplastic patients who received a total of 59 courses of cisplatin 80-100 mg/m2. In all cases hypersideraemia developed within 24 hours: iron mean value increased from 70.5 micrograms/dl to 237.4 micrograms/dl (p less than 0.001). Return to basal levels was achieved after 8-9 days. Indirect bilirubin, lactic-dehydrogenase, haemoglobin and red cells levels remained unmodified; reticulocyte count decreased only after 4 days, so making unlikely that a drug-induced haemolysis or a reduced iron utilization by inhibitory effect of cisplatin on erithron could be the cause of hypersideraemia, which at this moment remains unexplained.

Adult↗
PubMedDate not supplied

Bruxing patterns in children compared to intercuspal clenching and chewing as assessed with dental models, electromyography, and incisor jaw tracing: preliminary study.

The purpose of the present study was to compare bruxing patterns in children with chewing and maximum intercuspal clenching as defined in a clinical and laboratory environment. Six non-bruxing controls and six children who actively bruxed according to parent reports were evaluated. Both control and experimental subjects were assessed by an initial questionnaire, intraoral examination, extraoral examination, dental study models, incisor mandibular tracking, and bilateral surface electromyographic recordings (e.g., EMG). Bruxing was defined as grinding, clenching, or both in combination. The clinical examination consisted of an intraoral examination of the dentition, number of occlusal contacts, and wear facets. Dental study models were used to substantiate the intraoral findings for occlusal contact and wear facets. The mandibular incisors position was tracked during opening, closing, laterotrusion, protrusion, and chewing and compared to the bruxing movements in the experimental subjects. Bilateral surface EMG signals from the temporalis and masseter muscles were recorded in three maximum intercuspal clenches, ten chewing cycles on sugarless gum, and during simulated bruxing. The dental contacts were equal in number bilaterally in both control and bruxing subjects. Both groups demonstrated wear facets, but the bruxing subjects had more facets. The wear facets indicated lateral excursions but not clenching. Only the incisor jaw tracking and bilateral EMG differentiated the bruxing patterns. In those subjects (n = 4) who clenched during bruxing, the EMG pattern was not similar to that of intercuspal clenching and demonstrated its own unique muscle recruitment for the temporalis and masseter muscles. In the subjects who exhibited lateral excursions for bruxing (n = 2), the pattern of muscle recruitment of the two-closing muscles in terms of amplitude was similar for both the bruxing and chewing gum. Our findings support a concept that bruxing may depend upon factors that modify coactivation of muscle recruitment and do not depend upon occlusal contacts.

Analysis of Variance↗