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Biomedical subjects

C Navarro

Publications and source records attributed to C Navarro.

At least 127 records · Page 7Linked to original sources
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↗
PubMed1993

Stereological and morphometric analysis of dermal fibroblasts before and after bone marrow transplantation in a case of mucopolysaccharidosis I Scheie phenotype.

Bone marrow transplantation (BMT) has been used therapeutically in several types of mucopolysaccharidoses (MPS) and other inherited metabolic disorders. Fibroblasts are severely affected in MPS due to the intralysosomal accumulation of glycosaminoglycans. We report a stereological and morphometric study at light and electron microscopy levels of dermal fibroblasts before and 21 months after BMT in a young girl with MPS I Scheie phenotype (MPS I-S). Dermal fibroblasts showed remarkable morphological changes although their density, expressed as number of fibroblasts per unit volume of dermis (number density), was not modified in the post-BMT samples as compared to pre-BMT ones. Stereological and morphometric parameters referring to cell characteristics of post-BMT fibroblasts (nuclear and cell surface densities, and both nucleus/cell and cell/nucleus volume densities) showed significant differences when compared with pre-BMT fibroblasts, and non-significant differences regarding control cells. On the other hand, quantitative parameters of the lysosomal compartment from post-BMT fibroblasts showed intermediate values between pre-BMT and control fibroblasts. These results, at cellular level, are in agreement with previous biochemical and clinical results, and clearly showed a progressive course to a non-pathological state. All parameters estimated may be considered useful tools in evaluating the success of BMT. These parameters provide quantitative data which can be statistically compared, showing the changes due to the reduction of storage material after BMT. Cell/nucleus volume density is especially interesting since not only is it easy to estimate, even by automatic procedures, but it could also constitute a numerical expression of skin anatomopathological analyses performed post-BMT.

Bone Marrow Transplantation↗
PubMed1993

Primary hypertrophic osteoarthropathy: another heritable disorder associated with patent ductus arteriosus.

Patent ductus arteriosus (PDA) is a congenital malformation that has been linked to diverse heritable and chromosomal disorders. Primary hypertrophic osteoarthropathy (HOA) is a rare heritable syndrome in which digital clubbing and periostosis become evident without any underlying illness. The objective of this article is to describe four patients with coexisting PDA and primary HOA. Surgical closure of the ductus showed no effect on the skeletal changes. Primary HOA should be included among the heritable disorders that may be associated with PDA.

Child↗
PubMed1993

Gastroprotective effect of zinc acexamate against damage induced by nonsteroidal antiinflammatory drugs. A morphological study.

The gastroprotective effect of zinc acexamate against gastric damage induced by different nonsteroidal antiinflammatory drugs (indomethacin, diclofenac, and piroxicam) was morphologically assessed in the rat glandular stomach by light and scanning electron microscopy. In addition, the capability of these antiinflammatory drugs to inhibit gastric prostaglandin E2 production was compared with their ability to induce gastric lesions. Microscopically, disappearance of mucus glycoprotein and exfoliation of the mucosal surface were the most common findings. Surface ultrastructural lesions varied from minimal lesions of the surface epithelial cells to deep erosions of the gastric mucosa with release of associated cellular elements and sloughing of the denuded lamina propria. Diclofenac elicited the most powerful inhibitory activity on mucosal prostaglandin E2 (98% inhibition vs control), closely followed by piroxicam (97.8%) and indomethacin (91.05%). Pretreatment of animals with zinc acexamate significantly increased the presence of mucus glycoprotein, maintained the continuity of the surface epithelial cells, and decreased the depth of the mucosal erosions. The degree of protection exerted by zinc acexamate varied with the antiinflammatory, but was always evident.

Aminocaproates↗
PubMed1993

Hepatic amyloidosis in intravenous drug abusers and AIDS patients.

The clinical and pathological features of four liver biopsies and 12 autopsies from 1981-1990 with hepatic amyloidosis were reviewed. All of the patients had a history of both intravenous and subcutaneous cocaine and heroin use with chronic suppurative skin ulcers. Five patients were proven to have the acquired immunodeficiency syndrome at autopsy. Systemic amyloidosis was diagnosed in only five out of the 16 patients prior to death. Hepatomegaly was present in 12 patients. The amyloid protein was AA in 14 and AL in one case. Definitive characterization of the amyloid substance was not possible in one case. There was no evidence of multiple myeloma or a plasma cell dyscrasia in the one patient with AL amyloid. The amyloid distribution in the liver was both parenchymal and vascular in 12 cases. Cholestasis, which appeared to occur preterminally, was the only histological finding that correlated with the patient's clinical condition. The histological pattern of amyloid in the liver could not predict the type of amyloid protein that was identified. Amyloidosis should be considered in the differential diagnosis of unexplained hepatomegaly in the acquired immunodeficiency syndrome with chronic suppurative infections.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Epidemic asthma in Cartagena, Spain, and its association with soybean sensitivity.

We conducted a matched case-control study to assess the association between epidemic asthma and soybean sensitivity in Cartagena, Spain. In skin tests, 81% of the cases and no control subjects were positive to the commercial soybean allergen; 87% of the cases and 12% of the controls were positive to the prepared soybean allergen; and 69% of the cases and 6% of the controls showed high levels of specific immunoglobulin E antibodies (odds ratio = 10; 95% confidence interval = 1.4-433). The association remained strong after adjustment for total immunoglobulin E and for 28 other allergens. The results indicate that soybean sensitivity may be causing asthma epidemics in Cartagena.

Adolescent↗
PubMed1993

The nik operon of Escherichia coli encodes a periplasmic binding-protein-dependent transport system for nickel.

The complete nucleotide sequence of the Escherichia coli nik locus, which has been suggested to encode the specific transport system for nickel, has been determined. It was found to contain five overlapping open reading frames that form a single transcription unit. Deduced amino acid sequence of the nik operon shows that its five gene products, NikA to NikE, are highly homologous to components of oligopeptide- and dipeptide-binding protein-dependent transport systems from several Gram-negative and Gram-positive species. NikA represents the periplasmic binding protein, NikB and NikC are similar to integral membrane components of periplasmic permeases, and NikD and NikE possess typical ATP-binding domains that suggest their energy coupling role to the transport process. Insertion mutations in nik genes totally abolished the nickel-containing hydrogenase activity under nickel limitation and markedly altered the rate of nickel transport. Taken together, these data support the notion that the nik operon encodes a typical periplasmic binding-protein-dependent transport system for nickel.

Adenosine Triphosphate↗
PubMed1993

Absence of a growth hormone effect on rat soleus atrophy during a 4-day spaceflight.

The objectives of the present study were to determine the size and enzyme properties of soleus fibers of rats subjected to a 4-day spaceflight (National Aeronautics and Space Administration, STS-41) and the effects of exogenous growth hormone (GH) on the atrophic response of the muscle. Four groups of rats were studied: 1) control (Con), 2) Con plus GH treated (Con + GH), 3) flight (Fl), and 4) F1 plus GH treated (Fl + GH). Cross-sectional area and the activities of succinate dehydrogenase and myofibrillar adenosinetriphosphatase (ATPase) were determined in fibers identified in frozen serial cross sections. Fibers were categorized immunohistochemically as slow, fast, or slow-fast on the basis of their reaction with slow and fast myosin heavy-chain (MHC) monoclonal antibodies. Fibers also were categorized as light or dark on the basis of their staining for ATPase at pH 8.6. After the 4-day flight, mean body weight was significantly decreased compared with control. The absolute and relative (muscle wt/body wt) soleus weights were significantly smaller in the Fl and Fl + GH rats compared with their respective ground-based controls. In both flight groups, the cross-sectional area of the light ATPase fibers was significantly smaller (approximately 30%) than control. Three of 11 flight rats had a higher proportion of fibers expressing both slow and fast MHCs than expected on the basis of the fiber type distribution in the 11 control rats. Mean fiber succinate dehydrogenase and ATPase activities were similar among the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗
PubMed1993

[Protection by zinc acexamate against gastric lesions induced by non-steroid anti-inflammatory agents].

The ability of different non-steroidal anti-inflammatory drugs (diclofenac, indomethacin, ketoprofen, naproxen and piroxicam) to inhibit gastric prostaglandin E2 production in the rat was compared with their damaging potential on gastric mucosa. The influence of treatment with zinc acexamate (ZAC) on these two parameters was also determined. ZAC treatment significantly decreased the degree of gastric damage elicited by all the antiinflammatories tested. The experimental data confirm the complexity of the gastrolesive effect exerted by anti-inflammatory drugs and that only part of such effect would be related with their inhibition of prostaglandin synthesis. These results indicate that the gastroprotection of ZAC does not exclusively depend on the effect on the synthesis of prostaglandins by the gastric mucosa, yet it can additionally be exerted through alternative mechanisms.

Aminocaproates↗
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↗