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Biomedical subjects

C Nava

Publications and source records attributed to C Nava.

At least 19 recordsLinked to original sources
PubMed1996

Hepatic and cardiac oxidative stress and other metabolic changes in broilers with the ascites syndrome.

The objective of this study was to evaluate the gluconeogenic response of in vitro stimulated hepatocytes from control broilers and broilers with clinical manifestations of the ascites syndrome. The basal rate of glucose synthesis from lactate was found to be threefold greater in sick birds than in the control group and stimulation obtained with epinephrine was found to be quantitatively similar in both groups. Under basal conditions, the hepatocytes from the sick broilers exhibited 60% more ammonium than the control birds. In addition, the quantification of thiobarbituric acid reactive substances, as indicators of cellular lipoperoxidation, showed an increase of over 100% in heart and liver of sick broilers fowl. In conclusion, the complex integrated response of gluconeogenesis to epinephrine is maintained in broilers with ascites, although their hepatocytes present changes compatible with those observed in cases of oxidative stress. It is not known whether this stress is a cause or a consequence of the ascites syndrome.

Adenosine↗
PubMed1995

Contraceptive choice in Vigevano, Italy, 1983-1993.

The authors, after general consideration of family planning programs, present a study of 22714 women, who, in the decade 1983-1993, required contraceptive protection from the Family Planning Centers in the region of Vigevano (Italy). The authors underline the importance of a protocol used before beginning treatment to help prevent women receiving methods carrying too great a health risk. The results show a very high prevalence of oral contraception, increasing in recent years with the introduction of triphasic pills, while use of intrauterine contraception seems to be declining. Other conventional methods, such as barrier (diaphragm and condom) and 'natural' methods, had a low incidence in the sample studied. The reasons for these behaviors are analyzed and the relative trends discussed.

Adolescent↗
PubMed1994

Face recognition as a function of social attention in non-human primates: an ERP study.

Epidural event related potentials (ERPs) were recorded from four squirrel monkeys (Saimiri sciureus) during the presentation of pictoral stimuli that comprised real human and monkey faces. Subjects viewed tachistoscopically presented stimuli belonging to four different categories: familiar and unfamiliar human faces, and familiar and unfamiliar monkey faces. Familiar faces were subcategorized into top, middle and bottom according to the perceived individual's dominance ranking in a social hierarchy, as rated by human judges observing the group's social behavior. Waveform peak components to monkey and human faces showed similarities in their spatial distribution. However, larger amplitude N1 and N2 components were elicited in response to monkey compared to human faces, particularly over lateral temporo-parietal sites. A similar trend was observed for the P3 component, with maximal differences along midline electrode site. Responses to familiar and unfamiliar monkey faces showed larger N1s to familiar monkey faces and larger P3s to unfamiliar monkey faces. N1 and P3 components elicited by human faces showed no significant differences between conditions. N2 amplitudes were larger over posterior sites for top-ranked monkeys and larger over frontal sites for middle- and bottom-ranked monkeys. Top-ranked human faces elicited the largest N2 components, middle-ranked faces the next largest, and bottom-ranked faces the smallest. N1, N2, and P3 latencies were similarly sensitive to the ranking of human but not monkey faces. These data suggest that non-human primates exhibit evoked potentials to conspecific and non-conspecific faces that are similar in morphology but different in function. Larger amplitude responses to monkey faces suggests increased processing for that category of stimuli. Additionally, monkey ERPs reflect familiarity with conspecifics but not with human faces. Finally, the social status of the perceived individual, or at least the perceived threat posed by an individual, affects the latencies and magnitudes of ERP components produced by the viewer. These data are consistent with social attention hypotheses which propose that higher status (i.e. more dominant or socially meaningful) members of a group receive more attention than lower status individuals.

Animals↗
PubMed1993

Event-related potentials in macaque monkey during passive and attentional processing of faces in a priming paradigm.

Epidural event-related potentials (ERPs) were recorded in monkeys using a priming (S1-S2) paradigm. One juvenile and 2 young adult macaque monkeys (Macaca fascicularis) viewed tachistoscopically presented pairs of faces in four possible combinations: human-human, monkey-monkey, monkey-human, human-monkey. Faces were presented upright to untrained subjects. Subsequently, one adult monkey was trained to associate the occurrence of a monkey-monkey pair of faces with juice reward. In a separate control experiment, the same stimuli were presented upside down. In both the upright and inverted conditions, adult monkey ERPs exhibited a P1-N1-P2 complex of peaks in the 400 ms following stimulus presentation. However, only upright faces elicited a prominent, widely distributed negativity (N4) in the 400-800 ms interval and a long-duration negativity (LDN) in the last 400 ms of the 1,400-ms epoch. N4 was earlier in latency, larger in amplitude, and larger over left hemisphere in response to monkey faces compared to human faces. It was also sensitive to the preceding or priming stimulus, exhibiting larger amplitudes when S1 matched S2 than when it did not. Trained monkey waveforms differed from untrained monkey responses in terms of the appearance of an N2-P3 complex. P3 was bilaterally symmetrical, larger in magnitude, and delayed in latency in response to monkey faces. The differences in components in the two conditions suggest that monkey ERPs can distinguish between passive and attentional processing of faces. N4 appears to reflect the recognition of conspecifics, is sensitive to priming, and occurs primarily over left hemisphere. Rewarded presentation of faces results in P3-like components that may reflect the novelty, meaningfulness, or active nature of the response. The differences in distribution between P3 and N4 suggest that they do not share the same neural sources.

Aging↗
PubMed1990

Effects of propranolol on GH responsiveness to repeated GH-releasing hormone stimulations in normal subjects.

The influence of beta-adrenergic blockade by oral propranolol on the variability of GH responses to GHRH and on GH responsiveness to repeated GHRH administrations was investigated. Eight normal volunteers underwent three tests on three separate occasions. Each test consisted of two administrations of 80 micrograms GHRH at 2-h intervals without other medication (test 1) or combined with oral administration of 80 mg propranolol 90 min before the first (test 2) or the second GHRH injection (test 3). In test 1 GH levels increased significantly after the first, but not the second GHRH bolus (net incremental area under the curve [nAUC], mean +/- SD: 1453 +/- 974 and 178 +/- 309 micrograms.l-1.(120 min)-1, respectively). In test 2 basal GH secretion was not influenced by propranolol administration, whereas the GH response to the first GHRH injection was significantly greater than in test 1 (2327 +/- 1814 micrograms.l-1.(120 min)-1; p less than 0.05). However, individual subjects showed the same variability of GH response as in test 1. The GH response to the second GHRH bolus remained negligible. In test 3 administration of propranolol 90 min before the second GHRH bolus led to a clear GH increase (690 +/- 1002 micrograms.l-1.(120 min)-1), not significantly different from the GH response to the first bolus (1796 +/- 1375 micrograms.l-1.(120 min)-1). However, only 4 subjects showed a marked restoration of the GH responsiveness to the second GHRH administration. In conclusion, oral administration of propranolol is able to increase GH responsiveness to GHRH without changing the great individual variability. The response to a repeated GHRH stimulation is only partially restored by propranolol.

Administration, Oral↗
PubMed1988

Presynaptic modulation of the release of GABA by GABAA receptors in pars compacta and by GABAB receptors in pars reticulata of the rat substantia nigra.

The effect of GABA agonists and antagonists on K+-stimulated [3H]GABA release was studied to assess how presynaptic GABA receptors modulate GABA release. The release was affected in a quite different manner in the pars compacta and in the pars reticulata. Muscimol markedly inhibited the release from the pars compacta but had no effect on the release from the pars reticulata. Baclofen inhibited the release from the pars reticulata without affecting the release from the pars compacta. Bicuculline itself facilitated the release from the pars compacta but inhibited the release from the pars reticulata. Picrotoxin facilitated the release from the pars compacta and had no effect in the pars reticulata. The results suggest that the release of GABA from GABAergic terminals in the substantia nigra of the rat brain is modulated by GABAA autoreceptors in the pars compacta and by GABAB receptors in the pars reticulata.

Animals↗
PubMed1987

Lymphocyte activation by B. subtilis spores.

The in vitro effect of Bacillus Subtilis spores (BSs) on lymphocyte activation was investigated by analyzing the kinetics of expression of the activation antigens MLR3, MLR4 and HLA-DR in cultures of peripheral mononuclear cells. It was found that BSs over a wide range of concentrations are capable of inducing an increased expression of these three markers and that at high BSs concentration the effect is both quantitatively and qualitatively similar to that induced by the mitogens PHA and ConA. These results suggest that T cells may be involved in the response to Bss.

Bacillus subtilis↗
PubMed1986

Synthetic growth hormone-releasing hormone (GHRH 1-44) in the differential diagnosis between hypothalamic and pituitary GH deficiency.

GH response to an iv bolus of growth-hormone-releasing hormone (GHRH 1-44, 2 micrograms/kg iv) was evaluated in 17 prepubertal children with total GH deficiency (GHD), 6 with partial GHD and in 7 prepubertal normal but short children tested as control. GH response to conventional pharmacological (insulin and arginine or L-Dopa) and physiological stimuli (sleep test) and to GHRH test was also compared. GHRH-induced GH peak occurred at variable times and marked heterogeneity in magnitude of the individual responses to this peptide was observed in GHD patients and in controls. GH increases after GHRH with a peak greater than 10 ng/ml suggested an hypothalamic origin of the GHD in 12 patients (8 with total GHD and 4 with partial GHD). A significant difference (p less than 0.025) of GH peak mean following GHRH administration between total GHD children and normal short children was found. GH response to GHRH injection was usually higher than to conventional stimuli. Nevertheless GH peak following GHRH administration was lower than GH peak following conventional stimuli in 6 children (2 partial GHD children and 4 normal ones). A normal short child failed to respond to GHRH test performed twice. GHRH test is an important diagnostic tool in order to point out hypothalamic GHD.

Adolescent↗
PubMed1985

Serum gonadotrophin pulsatile secretion in men with Prl-secreting and non-secreting pituitary tumours.

In order to investigate the possible influence of prolactin (Prl) at the hypothalamic level, serum LH and FSH pulsatility was studied in 16 male patients with prolactinomas, normally LH responders to GnRH (group A): 8 of them were untreated (group A1) and 8 had undergone previous unsuccessful pituitary treatments (group A2). In 7 patients the study was repeated when serum Prl was normalized by bromocriptine treatment (group B). For comparison the secretory pattern of LH and FSH was studied in 6 male patients with non-secreting pituitary tumours (group C). All parameters of LH pulsatile secretion (i.e. arithmetic mean of the single concentration, coefficient of variation from the mean value, frequency of peaks, amplitude of pulses expressed as either absolute or per cent value) were significantly lower in patients of groups A1, A2 and C than in normal subjects and no difference was found between the three groups. Furthermore the 7 patients with prolactinomas studied both before and after bromocriptine-induced Prl normalization showed no difference in all the parameters of LH pulsatility in both conditions. No significant abnormalities of FSH secretory pattern were found in the patients of groups A1, A2, B and C in comparison to normal subjects. In all groups of patients mean serum testosterone basal levels were significantly lower than in normals, while the mean oestradiol-17 beta basal concentration was normal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma↗
PubMed1985

Skin pathology in industrial workers exposed to synthetic corticosteroids.

Systemic and cutaneous side effects observed in some workers of a company producing synthetic corticosteroids are described. The production process and the results of clinical and laboratory investigations are shown. A high incidence of skin and internal disorders (erythema, telangiectasia, acne, purpuric lesions and inhibition of the pituitary-adrenal axis) were found.

Acne Vulgaris↗
PubMed1983

RBE of spleen CFU-S to low dose rate Cf-252 or photon radiation in vivo.

The biological effects of low dose rate (LDR) Cf-252 radiation were compared to LDR Cs-137 photon radiation and acute 60Co radiation. The RBEn for endogenous CFU-S in vivo was 2.1 for neutron radiation at a dose rate of 9.9 cGy/hr of Cf-252 radiation. The value was consistent with previous in vitro experiments where a value of 2.1 was found. For the low doses and low dose rates studied, we tested an acute assay dose following the LDR irradiation to determine dose-effect and RBEn. Organ size shrinkage and regeneration patterns after LDR Cf-252 and Cs-137 were also studied and showed greater growth delay for Cf-252 irradiated lympho-hemopoietic tissues.

Animals↗
PubMed1983

Excess of beta-subunit of thyrotropin (TSH) in patients with idiopathic central hypothyroidism due to the secretion of TSH with reduced biological activity.

alpha-Subunit and beta-subunit of TSH were measured in the sera of five patients with idiopathic central hypothyroidism due to the secretion of biologically inactive TSH, in seven normal controls matched for bone age and sex, and in five subjects with mild primary thyroid failure before and after TRH (200 micrograms, iv) stimulation. Basal serum alpha-subunit concentration in patients did not differ from that in normal controls (mean +/- SD, 0.40 +/- 0.20 vs. 0.38 +/- 0.28 ng/ml; P, NS), whereas TSH and TSH-beta were significantly higher in patients (TSH, 1.51 +/- 0.74 vs. 0.59 +/- 0.53 ng/ml, P less than 0.025; TSH-beta, 0.56 +/- 0.18 vs. 0.10 +/- 0.02 ng/ml, P less than 0.001). The concentration of TSH-beta was also significantly higher in patients with central hypothyroidism than in subjects with mild primary thyroid failure (0.56 +/- 0.18 vs. 0.24 +/- 0.08 ng/ml; P less than 0.01), although serum TSH levels did not differ in the two groups (1.51 +/- 0.74 vs. 2.16 +/- 0.52 ng/ml; P, NS). alpha-Subunit was significantly higher in primary hypothyroid subjects (1.50 +/- 0.87, P less than 0.05 compared with patients with central hypothyroidism). After TRH, alpha-subunit, TSH, and TSH-beta net increases (peak) were significantly higher in patients with central hypothyroidism than in normal controls (alpha-subunit: 0.95 +/- 0.5 vs. 0.47 +/- 0.19 ng/ml, P less than 0.05; TSH: 7.1 +/- 3.1 vs. 2.9 +/- 1.8 ng/ml, P less than 0.005; TSH-beta: 0.89 +/- 0.35 vs. 0.22 +/- 0.18 ng/ml, P less than 0.005), whereas they did not significantly differ from those recorded in hypothyroid controls. The beta/alpha ratio, which was 1.67 +/- 0.86 in patients and 0.35 +/- 0.18 in normal controls (P less than 0.005), slightly decreased after TRH to 1.24 +/- 0.78 in patients, but remained unchanged in normal controls (0.39 +/- 0.1). After TRH the alpha-subunit peak occurred at 20 min both in patients and in controls, whereas TSH and TSH-beta peaked at 60 min in patients and at 20 min in controls. One patient was given oral TRH (40 mg/day for 4 weeks). The beta/alpha ratio fell from 1.85 to 0.13. Interestingly, serum thyroid hormones, which did not increase after iv TRH and after the first doses of oral TRH, showed a definite increase. Sera from two patients were filtered on Sephadex G-100: in one of them TSH-beta eluted in the same position as labeled reference standard, whereas in the other one radioimmunoassayable TSH-beta eluted near the void volume. The above data indicate that in patients with idiopathic central hypothyroidism due to biologically inactive TSH there is an excess of circulating TSH-beta and suggest that TRH is implicated in the secretion of TSH of full biological potency.

Adult↗
PubMed1983

Clinical use of pre- and postsurgical evaluation of abnormal GH responses in acromegaly.

The criteria by which acromegalic patients are considered "cured" after surgical therapy are still controversial. Since the abnormal growth hormone (GH) increase after the administration of some agents has been demonstrated to be characteristic of the tumoral somatotrophs, its disappearance after surgery may be taken as an index of the complete removal of the tumor. Serum GH increases after thyrotropin-releasing hormone (TRH, 200 micrograms intravenously), gonadotropin-releasing hormone (Gn-RH, 100 micrograms intravenously), and sulpiride (100 mg intramuscularly) injected during dopamine infusion (DA-Slp test), were evaluated in 68 acromegalic patients before and after transnasosphenoidal adenomectomy, and every 12 to 18 months during a follow-up period of 6 months to 11 years (average 42 months). Forty-two patients had abnormal responses to at least one test before surgery: 32 out of 68 (47%) to TRH, six out of 40 (15%) to Gn-RH, and 20 out of 28 (71%) to the DA-Slp test. Of 18 patients who underwent all three tests, 78% had abnormal responses to at least one of them. Twenty-three patients became unresponsive after surgery, and none of them had a recurrence or became abnormally responsive again during the follow-up period. Three out of six patients with postoperative serum GH levels between 5.1 and 10 ng/ml and three out of six patients with postoperative serum GH levels between 2.1 and 5 ng/ml remained abnormally responsive: one of them relapsed 1 year after the operation. The abnormal responses were lost in all 11 patients whose postoperative serum GH levels were below 2 ng/ml, and abnormal responses were maintained in all the patients in whom surgery was considered unsuccessful because postoperative serum GH levels were higher than 10 ng/ml. The TRH, Gn-RH, and DA-Slp tests should thus be considered useful tools in verifying the total removal of an adenoma. The reappearance of active acromegaly in the patient with low postoperative GH levels, who was still responsive to TRH, should be regarded as a reactivation and not a true recurrence of the disease.

Acromegaly↗
PubMed1982

Evidence for host resistance in 1,3 bis(2-chloroethyl)-1-nitrosourea treatment induced in syngeneic LSA lymphoma.

The anticancer agent 1,3 Bis(2-chloroethyl)-1-Nitrosourea (BCNU) cures the advanced syngeneic LSA lymphoma of C57BL mice with high efficiency. The cured animals resist further tumor challenge by large numbers of viable syngeneic tumor cells. Growth assays of spleen proliferation of the intravenously inoculated tumor revealed a progressive-regressive pattern of spleen growth after LSA-tumor injection. Lymphoma colony forming units (LCFU) in the spleen initially increased then regressed. In vitro assays of serum showed a lack of cytotoxic activity in mice cured by BCNU. Added spleen, thymus, or bone-marrow cells were similarly ineffective. Spleen and bone-marrow cells from immune mice passively transferred to normal mice showed weak cytotoxic activity against the LSA tumor. BCNU-cured mouse cells were more effective in protection than those cured with Chlorozotocin (CLZ).

Animals↗
PubMed1982

Effectiveness of penicillin irrigation in control of infection in sutured lacerations.

We studied the incidence of infection in lacerations in a controlled, double-blind, Armitage sequential clinical trial. After standard prescribed preparation of the wound area, and immediately before suture, each laceration was flooded with the 10 ml content of a numbered, amber glass vial. Half of the vials contained a solution of 0.9% NaCl; half contained a 5% solution of sodium benzyl penicillin. No other factors were controlled. A single observer made the determinations of presence or absence of infection, purulent or nonpurulent, early and late after suture. After study of 260 lacerations the study indicated a clear superiority of penicillin over saline in lowering the incidence of infection with a statistical significance of p less than 0.00005. In a sample of this size the 95% confidence limits of the magnitude of the superiority of penicillin cover a wide range, but it appears that two out of three or three out of four infections can be averted merely by flooding the wound with penicillin immediately before suture.

Clinical Trials as Topic↗