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Biomedical subjects

C Navarro

Publications and source records attributed to C Navarro.

At least 19 recordsLinked to original sources
PubMed1995

Genomic stability and wild-type p53 function of lymphoblastoid cells with germ-line p53 mutation.

Increased cancer risk associated with germ-line p53 mutation was linked to a deficit in the ability to maintain genomic stability. Accordingly, normal fibroblasts from cancer-prone individuals accumulate genomic aberrations with concomitant loss of wild-type p53 allele during in vitro culture. We tested whether such changes also occur in EBV-immortalized lymphoblastoid cells. Both normal and p53 germ-line mutant lymphoblastoid cells maintained functional p53 and genomic stability during long term in vitro culture. These unexpected differences between fibroblastic and lymphoblastic cells suggest that phenotypic expression of p53 deficiency is cell type specific. This could contribute to selective tissular localization of tumours observed in patients with Li-Fraumeni syndrome despite the presence of a mutant p53 allele in all cells.

Alleles↗
PubMed1995

Transmucosal potential difference in experimental colitis in rats.

Colon transmucosal potential difference (TPD), macro- and microscopic lesions, myeloperoxidase activity, and leukotriene levels were studied after the induction of experimental colitis in the rat. Forty-three male Wistar rats were subjected to the instillation of 200 mg/ml 2,4,6-trinitrobenzenesulfonic acid (TNB) solution through a rectal cannula. TPD measurements were made at different distances from the anus before and 24 h and one, two, three, and four weeks after lesion induction. Leukotriene B4 levels were assayed by intracolonic dialysis 24 h and one, two, three and four weeks after lesion induction. Macro- and microscopic evaluations were made of the bowel lesions, and myeloperoxidase activity was assayed. The mean basal TPD was -46.06 mV at 1 cm from the anus, and +10.86 mV in the proximal colon. Twenty-four hours after lesion induction the values proved markedly positive. This was correlated with an abrupt increase in LTB4 levels and myeloperoxidase activity. After one week the TPD values exhibited a greater electronegativity, returning to basal values by the fourth week after lesion induction. This coincided with an improved macroscopic lesion index, LTB4 levels, and myeloperoxidase activity. In conclusion, TPD is a useful indicator of acute colonic lesions and correlates well with LTB4 and myeloperoxidase assays. Moreover, the parameter is able to delimit lesion evolution, reflecting possible ad integrum restoration of the bowel mucosa.

Animals↗
PubMed1995

Cytoprotective and antisecretory activity of a ranitidine-zinc complex.

The effects of a ranitidine-zinc complex and ranitidine alone were compared in three different experimental models (pyloric ligation, ethanol and indomethacin) of gastric ulceration in the rat. In the pyloric ligation model, the ranitidine-zinc complex (50, 100 and 150 mg/kg p.o.) showed antiulcerogenic activity similar to that observed with equimolar doses of ranitidine (35, 70 and 105 mg/kg p.o.). Both the ranitidine-zinc complex and ranitidine significantly reduced (p < 0.05) gastric acid secretion in a dose-dependent manner. The protective effect of the ranitidine-zinc complex (100 and 150 mg/kg p.o.) against gastric damage developing after p.o. administration of absolute ethanol or indomethacin was enhanced (p < 0.05) with respect to that obtained with equimolar doses of ranitidine (70 and 105 mg/kg p.o.). The presence of zinc in the ranitidine-zinc complex does not interfere with the antisecretory effects of ranitidine on the gastric mucosa, while it confers an additional cytoprotective action to the final compound.

Animals↗
PubMed1994

Antagonistic effect of nickel on the fermentative growth of Escherichia coli K-12 and comparison of nickel and cobalt toxicity on the aerobic and anaerobic growth.

The facultative anaerobic enterobacterium Escherichia coli requires the activity of nickel-containing hydrogenase for its anaerobic growth. Deficiency of the specific nickel transport system led to a hydrogenase-minus phenotype and slowed down the fermentative growth in the nik mutant. Addition of 300 microM nickel to the growth medium could restore the hydrogenase activity. This restoration resulted in the recovery of anaerobic growth. A further increase of nickel concentration inhibited growth. Thus nickel shows an antagonistic effect on the anaerobic growth of E. coli. To study the mechanism of nickel toxicity, two classes of nickel-resistant mutants were isolated. The nkr mutant was obtained by selecting colonies grown on nickel-containing minimal plate. It acquired simultaneously the resistance to cobalt. A nonspecific magnesium transport mutant corA was isolated on cobalt-containing plate. The corA mutant was also resistant to nickel. When analyzing the influence of nickel and cobalt on the bacterial growth, we obtained two interesting observations. First, anaerobic growth was less sensitive than aerobic growth to cobalt toxicity. In contrast, nickel toxicity did not vary from the growth conditions. Second, cobalt seems to abolish the growth, while nickel appears to slow down the growth rate under the condition used.

Aerobiosis↗
PubMed1994

[Congenital muscular dystrophy: report on 10 cases].

Clinical features in 10 cases (3 males, 7 females) with congenital muscular dystrophy (CMD) are reported. Six patients suffered from pure forms of CMD. Two patients had diffuse cerebral white matter involvement of both hemispheres, demonstrated by computerized tomography and magnetic resonance imaging. Two patients were diagnosed as having Walker-Warburg syndrome on the basis of clinical and neuroradiological findings. The present series of patients further illustrates the heterogeneity of the various entities included under the term CMD even when central nervous system involvement is not suspected.

Biopsy↗
PubMed1992

The causal link between human papillomavirus and invasive cervical cancer: a population-based case-control study in Colombia and Spain.

To evaluate the association between human papillomavirus (HPV) and cervical cancer, we performed a population-based case-control study in Columbia and Spain, the former country having an incidence rate of cervical cancer about 8 times higher than the latter. It included 436 cases of histologically confirmed invasive cervical cancer and 387 randomly selected population controls. Information on demographic variables, sexual behaviour and other risk factors was obtained by interview. HPV-DNA was measured in cervical-swab specimens with 3 hybridization assays: ViraPap, Southern hybridization (SH) and polymerase chain reaction (PCR). The presence of HPV-DNA and detection of types 16, 18, 31, 33 and 35 were strongly associated with cervical cancer in each country regardless of the assay used. For both countries combined the adjusted odds ratios and 95% confidence intervals were: ViraPap OR = 25.9 (10.0-66.7); SH OR = 6.8 (3.4-13.4); and PCR OR = 28.8 (15.7-52.6). HPV-16 was the most common type detected in both cases and controls. Our results indicate that there is a very strong association between HPV 16, 18, 31, 33 and 35 and invasive cervical cancer and that this association is probably causal.

Carcinoma, Squamous Cell↗
PubMed1992

Enzyme and size profiles in chronically inactive cat soleus muscle fibers.

Spinal isolation (SI), i.e., the isolation of the lumbar spinal cord via a rostral and a caudal cord transection and bilateral dorsal rhizotomy, was used to determine the effects of chronic (6 months) inactivity on the size and metabolic properties of fibers in the cat soleus. Fibers were classified as dark or light, based on their staining reactions to myosin ATPase, alkaline preincubation, and immunohistochemically as expressing fast and/or slow myosin heavy chains (MHC). Succinate dehydrogenase (SDH) and alpha-glycerophosphate dehydrogenase (GPD) activities were assessed histochemically. Following SI, both the light and the dark ATPase fibers in the SI cats were significantly smaller than the light ATPase fibers in the controls. Normally 100% of the fibers were light ATPase and reacted exclusively with the slow antibody. After SI, approximately 45% of the fibers were dark ATPase fibers, many reacting with both fast and slow MHC antibodies. The total amount and concentration of GPD were higher in the light and dark ATPase fibers in SI compared with light ATPase fibers in controls. In contrast, although the total amount of SDH per fiber was decreased, reflecting the decrease in fiber size, the mean SDH concentration per fiber was unchanged following SI. These data indicate that there is a close coordination in the regulation of GPD activity and the type of myosin. SDH activity, on the other hand, appears to be resistant to decreased levels of activity and unloading, i.e., there seems to be a minimum level of oxidative potential in the soleus that is independent of activity level. Fiber sizes, however, are very sensitive to less-than-normal amounts of neuromuscular activity and/or loading.

Adenosine Triphosphatases↗
PubMed1992

Diagnostic value of conization of the uterine cervix in the management of cervical neoplasia: a review of 756 consecutive patients.

A review of 584 consecutive cases of conizations performed over a 15-year period showed that 320 patients (54.8%) had conizations because of the presence of neoplastic cells in the endocervical curettings. Of these patients, 268 (83.4%) had cervical intraepithelial neoplasia of various grades on conization, and 12 (3.6%) had microinvasive cancer. The remaining 40 patients had normal cervical epithelium. One hundred seven (18.3%) patients had conization because of cytological smear and colposcopy discrepancy. Seventy-six (71.0%) patients in this category had cervical intraepithelial neoplasia. Two (2.0%) had superficially invasive cancer; the remaining 29 patients had normal cervical histology. Sixty-seven (11.5%) had conizations because of unsatisfactory colposcopic evaluations. This review indicates that although conization is less frequently performed, it is still a useful tool in the management of patients with abnormal cytology in whom colposcopy evaluation cannot rule out invasive cancer.

Adolescent↗
PubMed1992

Enhancement of human natural killer cell activity by opioid peptides: similar response to methionine-enkephalin and beta-endorphin.

We studied the effect of methionine-enkephalin (MET) and beta-endorphin upon human peripheral blood lymphocyte natural killer cell (NKC) activity in a group of healthy volunteers (n = 27; 17 male and 10 female, age +/- SD and range of 32 +/- 6, 25-43 years and 36 +/- 11, 22-65 years, respectively). Aliquots from some individual samples were preincubated separately with different concentrations of either peptide (n = 12), while others were tested with only one of these substances (MET, n = 6; beta-endorphin, n = 9). Using each individual as its own control, MET (10(-8) and 10(-6) M) and beta-endorphin (10(-10) and 10(-8) M) significantly increased NKC activity (NKCA) (at least 20% over base value, effector-to-target cell ratio, 40:1) in 7 out of 15 and 7 out of 19 subjects, respectively. Results obtained from the rest of the samples were mixed, e.g., changes observed in NKCA were not significant or showed significance with only one of the peptide concentrations studied. Cells from individuals showing a significant increase in NKC lytic function following preincubation with either MET or beta-endorphin responded similarly to the other peptide (in both cases 5 out of 6 subjects), suggesting that enhancement of NKCA by MET and beta-endorphin may work through a similar mechanism.

Adjuvants, Immunologic↗
PubMed1992

Comparison of ViraPap, Southern hybridization, and polymerase chain reaction methods for human papillomavirus identification in an epidemiological investigation of cervical cancer.

In order to provide a reliable diagnosis for the presence and type of human papillomavirus (HPV) DNA in a case-control study of cervical cancer in Colombia and Spain, 926 cervical scrapes from female subjects were examined by ViraPap (VP) and Southern hybridization (SH), and 510 of these (263 cases and 247 controls) were also tested by polymerase chain reaction (PCR) using the HPV L1 consensus primers. HPV DNA prevalence was much higher in cases than in controls by each of the three tests. There was complete agreement between the results of the three tests for 64.9% of the 510 specimens; 53.5% were negative and 11.4% were positive (regardless of type) by all tests. An additional 29.0% of the specimens were positive by PCR: 19.4% by PCR alone, 6.7% by PCR and VP, and 2.9% by PCR and SH. SH and/or VP gave positive results for 6.0% of the specimens for which the PCR finding was negative: 2.7% by SH alone, 2.5% by VP alone, and 0.8% by both VP and SH. When specimens which were positive by VP alone or only by SH at low-stringency conditions were excluded, PCR confirmed all but four specimens which were positive by other tests. The concordance between type-specific diagnosis by SH and PCR was 86% when HPVs were typed in both tests. HPV-16 accounted for over 80% of the typed HPVs in each test. The presence of blood in case specimens did not appear to inhibit HPV positivity by VP or by PCR at the dilution tested. Low amounts of cellular DNA of specimens resulted in some underestimation of HPV positivity by VP and SH but not by PCR. Compared with that of PCR, the sensitivities for case specimens were 38% by SH and 50% by VP; the sensitivity for control specimens, although it could not be measured precisely because there were few positive specimens, appeared to be lower than for case specimens. It was concluded that PCR-based tests are best suited for epidemiological investigation of HPVs.

Adult↗
PubMed1992

Morphological study of gastric lesions developing in the rat under several damaging conditions: modifications induced by pretreatment with zinc acexamate.

Lesions developing in the gastric mucosa of the rat after exposure to different gastric damaging agents (100 mg/kg aspirin, and 70% or 100% ethanol) were assessed by scanning electron microscopy. The severity of the lesions was quantified according to morphological criteria. Modifications in the severity of these lesions induced by pretreatment with zinc acexamate were also analyzed. The scanning electron microscope revealed that with the exception of absolute ethanol, which caused distinctive morphological features, lesions found under the different experimental agents shared a common pattern of progression. Ultrastructural lesions on surface epithelial cells preceded further alterations of parietal cells. After the integrity of the epithelial cells was lost, detachment of the parietal cells occurred, probably, through peptic digestion of the connections between cells and their extracellular matrices. Pretreatment of animals with zinc acexamate increased the presence of mucus on the gastric surface and significantly prevented the progression of lesions towards the severest stages. Ultrastructural damage of surface epithelial cells was not influenced by this treatment, but detachment of damaged cells was clearly diminished. These data confirm the protective effect of zinc acexamate against gastric aggressions. Moreover, our studies confirm the notion that mucus secretion and maintenance of continuity on the gastric lumen by surface epithelial cells is of critical importance in preventing the gastric damage induced in these experimental models.

Aminocaproates↗
PubMed1992

[Cerebral amyloid angiopathy and recurrent cerebral hematoma. Clinicopathological study of a case].

Cerebral amyloid angiopathy (CAA) is an almost constant finding in Alzheimer's disease and in Alzheimer type senile dementia (EA/DSTA) but it has also been described in association with other processes such as in age-related hereditary or non hereditary cerebral hemorrhage (CH) relapse. The case of a non hypertensive 78 year old women is presented. Over a period of 27 months the patient had 3 cerebral hemorrhages located in the left parietotemporal, caudate nucleus and right frontobasal and right parietotemporal lobes, all of which had cortico-subcortical topography and eruption of blood to the subarachnoid space. The fundamental finding in the neuropathological study was the CAA with massive involvement in the leptomeninges and cortex, less in cerebellum and nucleus of the base, occasional in white matter and absent in the brain stem trunk. Abundant senile plaques and figures of neurofibrillar degeneration were found. Granulovacuolar degeneration or Hyrano bodies were not observed. At the level of the main intracraneal arterial trunks only a small plaque of atheroma was observed in the left vertebral artery. The association of CAA and CH in the literature and their relation with EA/DSTA are revised.

Aged↗