Search PubMed⌕ Search

Biomedical subjects

M Poli

Publications and source records attributed to M Poli.

At least 73 records · Page 4Linked to original sources

A study of misbehavior: token reinforcement in the rat.

The purpose of this research was to investigate the phenomenon of misbehavior described by Breland and Breland (1961). Rats were trained to obtain ball-bearings and drop them in a hole for food or water reinforcers. In confirmation of the Brelands' observation, many subjects were slow to deliver the balls, and frequently attempted to chew them before they were dropped. A series of four experiments, in which the same rats were used throughout, showed that delivery times tended to be longer with food than with water, and that these times increased when nylon balls were substituted. The effect of motivational level was investigated by varying both deprivation and amount of prefeeding; no effect on delivery time was detected, although other measures of performance were affected by motivational factors. Similar results were obtained in a final experiment that employed a new set of naive subjects. The studies demonstrated that misbehavior can be studied in an experimental situation, and the results supported an analysis in terms of competition between stimulus-reinforcer and response-reinforcer contingencies. The question of why such effects have not been reported in previous token reinforcer studies was unanswered.

Journal Article↗

Effect of vincristine on glucose-induced insulin secretion in man.

60 min after the injection of therapeutic doses of vincristine for cancer chemotherapy, there is a reduction of the total (40%) and of the acute phase (43%) areas of insulin secretion inductedby 5-g i.v glucose load, and the constant of gllcose utilization is reduced by 25%. No differences are observed after 3 5-g i.v. glucose loads given at hourly intervals in control subjects.

Blood Glucose↗

Orientation and rotational freedom of fluorescent probes in lecithin bilayers.

The fluorescence polarization properties of lecithin bilayers stained with 2,6-MANS and 1,8 ANS under applied potential steps have been studied. The fluorescence signal components of both dyes were found to have different sign and relative amplitude, suggesting that 1,8-ANS and 2,6-MANS behave differently when bound to black lipid membranes. In order to determine the location and the extent of rotational brownian motions of the bound chromophores, the experimental data were analyzed by using a simplified physico-mathematical model. According to it 2,6-MANS appears to have a ratio rho/tau higher than 1.8-ANS (rho being the rotational relaxation of in plane rotations and tau the lifetime of the excited singlet state of the bound molecules), suggesting that the former chromophore is more tightly held inside the bilayers. Furthermore, 2,6-MANS is found to possess the absorption and emission oscillators more closely oriented to the normal of membrane surface, while 1,8-ANS has both oscillators almost near the plane of the bilayers. The results furnish also a fair estimate of the random molecular motion own by the phospholipid molecules at room temperature. The comparison of the present data with those obtained from squid axon membranes confirms the validity of the proposed physical model, yielding a rough estimate of the axon membrane-area covered by integral protein macromolecules. These preliminary results derived from lecithin model membranes suggest that fluorescence polarization techniques can provide valuable informations if applied to study the macromolecular organization of in vitro reconstituted membranes.

Animals↗

Response additivity: effects of superimposed free reinforcement on a variable-interval baseline.

Three experiments examined the effects of superimposing free reinforcement (Free VI 30-sec) on behavior maintained by a response dependent mult VI 2-min VI 2-min schedule of reinforcement. Experiment I used pigeons as subjects, key pecking as the response, and colors of response key as the stimuli associated with the multiple-schedule components. When free reinforcement was added during only one component (Differential condition) a large and highly significant increase in response rate developed in this component. Adding free reinforcement during both components (Nondifferential condition) produced smaller and far less-consistent effects. An entirely different pattern of results was obtained in two subsequent experiments, where similar procedures and reinforcement conditions were used with rats as subjects and bar pressing as the response. In both Experiments II and III, response rates decreased to the stimulus associated with added free reinforcement in the Differential condition. These findings are interpreted as the result of interactions between behavior maintained by response-reinforcer contingencies and behavior maintained by stimulus-reinforcer contingencies. As such, they support the main assumption of an autoshaping theory of behavioral contrast, that additivity of responding generated by the two kinds of contingency can occur only in situations favorable to autoshaping.

Journal Article↗

Use of bioelectric impedance analysis (BIA) in children with alterations of body water distribution.

Validation studies of bioelectric impedance analysis (BIA) were performed in children with obesity, Duchenne muscle dystrophy and juvenile rheumatoid arthritis. BIA allowed an accurate assessment of total body water in all groups (CV from 4.1 to 5.1%). However, the prediction of extracellular water by BIA was not always satisfactory (CV from 8.5 to 12.5%), being better in the groups of children with the lowest variability in body water distribution.

Arthritis, Juvenile↗

Sensitivity and specificity of body mass index and skinfold thicknesses in detecting excess adiposity in children aged 8-12 years.

PRIMARY OBJECTIVE: The study aimed to evaluate the sensitivity (SN) and specificity (SP) of body mass index (BMI) and skinfold thicknesses in detecting excess adiposity in children. RESEARCH DESIGN: Cross-sectional. MATERIALS AND METHODS: 986 children (500 females and 486 males) aged 10 +/- 1 years (mean +/- SD; range: 8-12 years) were studied. All underwent anthropometric measurements and bioelectrical impedance analysis (BIA). Dual-energy X-ray absorptiometry (DXA) was performed in 52 children to develop a population-specific algorithm for the assessment of fat-free mass (FFM) from BIA. The algorithm was applied to the remaining 934 children to estimate their FFM. Fat mass (FM) was obtained by subtracting FFM from weight (Wt). Values of FM:Wt were transformed in Z-scores and converted into 19 percentile categories (from 5 to 95 in steps of 5). The same procedure was performed with BMI and the log-transformed sum of four skinfold thicknesses (triceps, biceps, subscapular and suprailiac; lt-4SF). Excess adiposity was defined as a level of FM:Wt greater than the internally derived 85th percentile. SN and SP of each internally derived percentile of BMI and lt-4SF in detecting excess adiposity were calculated. RESULTS: In the pooled sample (n = 934), SN and SP were 0.39 and 0.99 for the 95th percentile of BMI, 0.65 and 0.95 for the 85th percentile of BMI, and 0.75 and 0.94 for the 85th percentile of lt-4SF. CONCLUSIONS: BMI percentiles employed in the present study have a high SP but a low SN in detecting excess adiposity in 8-12-year-old children. The use of the sum of four skinfolds has the potential to increase the SN of a screening programme for excess adiposity in children of this age.

Absorptiometry, Photon↗

Relationship between body composition and bone mineral content in young and elderly women.

PRIMARY OBJECTIVE: To study the relationship between bone mineral content (BMC), lean tissue mass (LTM) and fat mass (FM) in a large sample of young and elderly women. RESEARCH DESIGN: Cross-sectional. METHODS AND PROCEDURES: BMC, LTM and FM were measured by dual-energy X-ray absorptiometry in 2009 free-dwelling Caucasian women aged 63 +/- 7 years (mean +/- SD; range: 37-88 years). The majority of women were postmenopausal (96%). RESULTS: LTM explained 13% more variance of BMC than FM (R(2)(adj) = 0.39 vs 0.26, p < 0.0001) but weight (Wt) explained 5% more variance of BMC than LTM (R(2)(adj) = 0.44, p < 0.0001). The prediction of BMC obtained from LTM and FM (R(2)(adj)= 0.46, p < 0.0001) was only slightly better than that obtained from Wt. After the effects of age, Wt and height (Ht) on BMC were taken into account by multiple regression, the contribution of LTM and FM to BMC was just one-fifth of that of Wt (R(2)(adj) for full models < or =0.56, p < 0.0001). After a further correction for bone area (BA), the contribution of LTM and FM to BMC was just one-tenth of that of BA and not different from that of Wt and Ht on practical grounds (R(2)(adj) for full models = 0.84, p < 0.0001). Thus, after inter-individual differences in age, Wt, Ht (and bone size) are taken into account, the relationship between body composition and BMC is substantially weakened. CONCLUSIONS: In Caucasian women, (1) LTM is a stronger predictor of BMC than FM, but (2) Wt is a better predictor of BMC than body composition for practical purposes, and (3) Wt and body composition are not able to explain more than 46% of BMC variance.

Adipose Tissue↗

Cross-calibration of eight-polar bioelectrical impedance analysis versus dual-energy X-ray absorptiometry for the assessment of total and appendicular body composition in healthy subjects aged 21-82 years.

AIM: To calibrate eight-polar bioelectrical impedance analysis (BIA) against dual-energy X-ray absorptiometry (DXA) for the assessment of total and appendicular body composition in healthy adults. RESEARCH DESIGN: A cross-sectional study was carried out. SUBJECTS: Sixty-eight females and 42 males aged 21-82 years participated in the study. METHODS: Whole-body fat-free mass (FFM) and appendicular lean tissue mass (LTM) were measured by DXA; resistance (R) of arms, trunk and legs was measured by eight-polar BIA at frequencies of 5, 50, 250 and 500 kHz; whole-body resistance was calculated as the sum R of arms, trunk and legs. RESULTS: The resistance index (RI), i.e. the height(2)/resistance ratio, was the best predictor of FFM and appendicular LTM. As compared with weight (Wt), RI at 500 kHz explained 35% more variance of FFM (vs 0.57), 45% more variance of LTM(arm) (vs 0.48) and 36% more variance of LTM(leg) (vs 0.50) (p < 0.0001 for all). The contribution of age to the unexplained variance of FFM and appendicular LTM was nil or negligible and the RI x sex interactions were either not significant or not important on practical grounds. The percent root mean square error of the estimate was 6% for FFM and 8% for LTM(arm) and LTM(leg). CONCLUSION: Eight-polar BIA offers accurate estimates of total and appendicular body composition. The attractive hypothesis that eight-polar BIA is influenced minimally by age and sex should be tested on larger samples including younger individuals.

Absorptiometry, Photon↗

Human papillomavirus infection in atrophic smears. A case report.

BACKGROUND: Human papillomavirus (HPV) infection in atrophic smears can be misleading and may produce the diagnosis of cervical intraepithelial neoplasia. CASE: A routine cervical smear in a 62-year-old female revealed an atrophic smear with nuclear changes suggestive of a high grade squamous intraepithelial lesion (HSIL). An estrogen cream for topical vaginal use was prescribed. A new smear was collected seven days later and revealed koilocytosis but no evidence of HSIL. CONCLUSION: Koilocytosis is a cellular finding of mature epithelial cells. The use of estrogen produces maturation of HPV-infected basal cells, allowing a correct diagnosis of this disease in patients with atrophic smears.

Atrophy↗

[Clinical evaluation of endometrial biopsy].

This study comprehends evaluation of endometrial biopsy performed between June 1986 and June 1989 in the Obstetric and Gynaecologic Department of Casorate Primo Hospital in fertile, perimenopausal and post-menopausal patients with uterine bleeding. The results show that on a total amount of 459 cases we registered 78 cases of initial abortions, 3 vesicular mola, 300 dysfunctional bleeding, 63 precancerous situations and 15 endometrial cancers. We confirm the diagnostic and prognostic validity of endometrial biopsy carried out with fractional curettage. The opportunity to prevent and diagnose precancerous pathology through a multiple screening is also estimated.

Biopsy↗

Enthesopathies and diabetes mellitus.

OBJECTIVE: There is evidence of a close relationship between diabetes mellitus and disorders of the insertions of tendons, ligaments and articular capsules into bone (enthesopathies). It has been suggested that these disorders may represent genuine complications of diabetes. We therefore conducted a study to determine whether insertion disorders at the calcaneum (calcaneal spurs) represent a complication of non-insulin-dependent diabetes. METHODS: The incidence of calcaneal spurs was studied in a group of 100 patients with non-insulin-dependent diabetes in comparison to 100 sex- and age-matched controls. Patients with disorders involving hyperostosis were excluded. RESULTS: Calcaneal insertion disorders were found to be more common among the diabetics than among the controls. These disorders, however, were also associated with other factors such as the body mass index and age. Discriminant analysis, which would have in theory highlighted any relationship between diabetes and insertion disorders at the calcaneum, did not show definitively that these disorders were a complication of diabetes. CONCLUSION: These results suggest that enthesopathies are not a complication of diabetes mellitus, and we would suggest that this conclusion may be extended to the relationship between diabetes and insertion disorders at other joints.

Adult↗

[Wegener's syndrome (or granulomatosis). A clinical case].

Wegener granulomatosis is characterized by focal necrotizing granulomatosis of the upper respiratory and pulmonary tracts, by a necrotizing vasculitis and focal necrotizing glomerulonephritis. Clinical symptoms typically include intractable sinusitis or persistent nasal obstruction, serous otitis media, hemoptysis and pleurisy. These symptoms can also be accompanied by intermittent fever, weight loss, myalgia and sensory neuropathy. The oral lesions, including palatal ulceration, lingual ulceration, aphthae, nonhealing extraction sockets, gingivitis, have been infrequently described. Wegener's granulomatosis occasionally presents in the early stages as a characteristic hyperplastic gingivitis, named by the authors "strawberry gums", which fails to respond to conventional periodontal therapy. A case is reported, in which this clinically distinctive gingivitis was the presenting lesion with the serous otitis, illustrating that less frequently occurring entities, such as Wegener's granulomatosis, should be considered in the differential diagnosis of localized gingival lesions which fail to respond to conventional therapy.

Adult↗

[Risk factors of endometrial carcinoma].

The authors base their experience on 12 women affected by endometrial carcinoma. Problems have been diagnosed in the post-menopausal and climacterium period, considering the clinical, hormonal and lipidic profile and some tumoral markers. The most risk factors for the endometrial adenocarcinoma have been collected in the adiposity with hypertension and hyperglycemia, above all in nullipara women with late menopause and dyslipidemia.

Adenocarcinoma↗

[Use of seat belts during pregnancy].

After a review of the world literature on the advantages and compulsiveness of seat belts, the authors recommend pregnant women to use them. Moreover, they invite gynaecologists and midwives to favour their use during psycho-prophylaxis courses.

Accident Prevention↗

[Piperacillin in prevention and therapy in gynecological surgery].

The authors have studied the use of sodic piperacillin in surgical gynecological prophylaxis. The drug, used in the intravenous tract, has proved efficacious for broad spectrum of antibacterial action versus gram+, gram-, and anaerobic and aerobic. It has shown an excellent tolerability by reducing hospital surgical infections (11% of cases) and sepsis (9.2% of cases) with social, economic and professional advantages.

Antibiotic Prophylaxis↗