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Biomedical subjects

G Arena

Publications and source records attributed to G Arena.

At least 19 recordsLinked to original sources
PubMed1992

Multicenter clinical evaluation of a new SSIR pacemaker.

A multicenter clinical evaluation of Sorin Swing 100, a new SSIR pacemaker with a gravimetric sensor, was performed by seven different centers enrolling a total of 89 patients, 56 men and 33 women, mean age 73.1 years, for pacemaker implantation (73 patients) or pacemaker replacement (16 patients). Pacing mode was VVIR in 73 patients and AAIR in 16. The behavior of pacing rate was evaluated 3 months after the implant by performing a 24-hour Holter monitor, an exercise stress test, and tests for the assessment of mechanical external interference (MEI). A physiological behavior of the paced rate was always observed during Holter monitoring. In 52 completely paced patients mean diurnal, nocturnal, and maximal heart rate were, respectively, 74.9 +/- 5.7 ppm, 58.1 +/- 5.8 ppm, and 113.4 +/- 12.7 ppm; a paced rate exceeding 100 ppm was reached on the average 5.6 times/Holter monitor. In all but two patients the sleep rate (55 ppm) was reached during the night or long resting time. During exercise stress test a direct correlation between the increase in pacing rate and the increase in workload was observed; the mean maximal heart rate reached in 49 completely paced patients was, respectively, 102.8 +/- 9 ppm in 17 patients who accomplished stage 1, 116.2 +/- 13.6 ppm in 28 patients who accomplished stage 2, and 133 +/- 6.7 ppm in 10 patients who accomplished stage 3 of the Bruce protocol. MEI testing never increased the pacing rate over the noise rate (10 ppm over the basic rate). In only seven patients the results obtained suggested to change the nominal set up of the pacemaker.(ABSTRACT TRUNCATED AT 250 WORDS)

Acceleration↗
PubMed1991

Chromosomal assignment of human O6-methylguanine-DNA-methyltransferase gene by hamster-human somatic cell hybrids.

Using an in vitro assay to measure O6-methylguanine-DNA-methyltransferase (MT) activity in cell extracts from a panel of human-hamster cell hybrids, we were able to locate the human MT gene on chromosome 10. Chinese hamster cells have little or no MT activity and the presence of human chromosome 10 was a necessary condition for MT activity in cell hybrids. In some cell hybrids carrying chromosome 10, however, MT activity was not higher than that of hamster cells. As an explanation for this result, genetic determinants repressing MT expression and/or activity might be present in other human chromosomes carried by MT-negative cell hybrids. Partial hyperploidy of the hamster karyotype, variable activity of the parental human cell lines and changes during subculturing of the cell hybrids might also account for the lack of enzymatic activity in chromosome 10 containing hybrids.

Animals↗
PubMed1990

O6-alkylguanine-DNA alkyltransferase activity in human brain tumors.

The O6-alkylguanine-DNA alkyltransferase (AT) activity in different kinds of human brain tumors was investigated. Twenty-seven brain tumors were analysed. Twenty-five of them showed proficient AT activity with values ranging between 20 and 722 fmol AT/mg protein. The two AT-deficient tumors observed were an oligodendroglioma and an astrocytoma. The relationship between the different histological kinds of tumor, with respect to the AT activity was: meningeomas greater than sarcomas greater than glioblastomas greater than astrocytomas greater than oligodendrogliomas greater than neurinomas greater than lymphomas. The proposal of Kohn (DNA filter elution methods in anticancer drug development. In: Concepts, Clinical Developments, and Therapeutic Advances in Cancer Chemotherapy. Editor: F.M. Muggia. Martinus Nijhoff Publishers, Boston) to confine treatments with alkylating antineoplastic agents to AT-deficient tumors, is discussed.

Animals↗
PubMed1990

Evaluation of rate-responsive pacemakers by transesophageal Holter monitoring of spontaneous atrial rate.

One of the most important problems in rate responsive (RR) pacing is the clinical experimental evaluation of the reliability of various sensors. In particular, it is difficult to test their sensitivity and specificity during daily activity of the patients. Atrial rate, when present and normal, is the most physiological marker of metabolic requirements, but sometimes it is impossible to analyze the P wave in ventricular paced rhythm during routinely performed tests (e.g., ergometric test and 24-hour Holter monitoring). During various physical activities, we monitored atrial electrograms on an esophageal lead on the first channel of a standard Holter tape recorder; on the second channel a surface ECG lead was recorded. We selected 10 patients with high grade heart block and normal sinus node function paced in RR-VVI mode. RR pacing was obtained using various sensors (body activity, blood temperature, spike-T interval, minute ventilation). The good quality of recording allowed an easy evaluation of atrial and ventricular rates. In four cases an appropriate increase in heart rate was documented; sensitivity threshold and/or rate response slope were reprogrammed when indicated. The pacing rate of one patient did not parallel the atrial rate during walking only. In three cases, we observed a delay in the ventricular rate increase, with ventricular rate decreasing at peak exercise despite further atrial rate increase. In the last two patients, we observed inappropriate pacing response; pacing rate increased later and to a lower level than the atrial one. This new method is applied easily and appears reliable to evaluate the response of RR pacemakers to individual metabolic needs.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

[Possible role of 06-methylguanine-DNA-transferase in the response of patients with primary tumor of the brain to chemotherapy using chloro-ethyl-nitroso-urea: results of a current study].

We have started a study to measure the MT activity in surgical specimens from high grade human malignant gliomas, with the dual aim to (i), know whether lack of activity can be demonstrated in these tumors, and (ii), relate the measured levels of MT to the histology of the tumors and to the response of patients to chemotherapy with 1-(2-Chloroethyl)-3-Cyclohexyl-1-Nitrosourea (CCNU). To date, 12 Gliomas have been assayed. In 11 tumors, MT activities ranging from 30 to 150 fmoles/mg protein have been measured. The only negative specimen derived from a patient who had received radiotherapy before surgery. At the present stage of the study, therefore, we have no unequivocal evidence for the existence of MT-deficient Gliomas.

Astrocytoma↗
PubMed1986

[Perineal functional rehabilitation in female urinary stress incontinence].

Since January 1985 13 female patients with urinary incontinence induced by pure stress have been subjected to perineal functional rehabilitation at the S. Giovanni Battista Hospital Functional Rehabilitation Service and Turin Health Service Unit 23 in collaboration with the hospital's Urology Division. The results are encouraging and suggest that this treatment may be a valid alternative to surgery.

Biofeedback, Psychology↗
PubMedDate not supplied

Zinc affects the metabolism of thyroid hormones in children with Down's syndrome: normalization of thyroid stimulating hormone and of reversal triiodothyronine plasmic levels by dietary zinc supplementation.

Levels of circulating thyroid stimulating hormone (TSH), tetraiodothyronine (T4), 3,5,3'-triiodothyronine (T3), and 3,3',5' triiodothyronine (reversal T3 or rT3) were measured in 25 children with trisomy of chromosome 21, also known as Down's syndrome (DS), and in 14 normal children. In subjects with DS TSH levels were increased, while plasmic levels of rT3 were decreased. No alteration in T3 and T4 levels was observed. Before zinc supplementation, plasmic levels of zinc and thymulin, a zinc dependent thymic hormone, were significantly decreased in DS children. After four months of dietary supplementation with zinc sulphate, a normalization of plasmic zinc, thymulin and TSH levels was observed. Plasmic levels of rT3 significantly increased, and after zinc treatment no difference was detectable between DS children and normal children. Clinical evaluation of the health status of DS children showed that zinc supplementation decreased the incidence of infectious diseases and improved school attendance. Thus, the increased efficiency of the immune system and the normalization of some endocrine parameters by zinc supplementation suggests that zinc deficiency may play a crucial role in some of the pathological manifestations associated with the syndrome, such as infections and malfunctioning of the thyroid gland.

Adolescent↗