Biomedical subjects

C Fernandez

Publications and source records attributed to C Fernandez.

At least 19 recordsLinked to original sources

PubMed1992

Genetic mechanisms for dominant VH gene expression. The VHB512 gene.

A total of 37 mAb with reactivity for dextran B512 have been studied; 30 of them were products of independent rearrangements and 21 made use of the same VH gene, the VHB512 gene. These results unambiguously established that the immune response to dextran in the high responder mouse strain C57BL/6 was restricted. Idiotypic determinants are located all over the Ig V region. Many but not all Id described so far can be ascribed to protein structures encoded by VH or VL gene segments. The expression of the major Id, 17-9 Id, in C57BL/6 was not absolutely correlated with the expression of the dominant VHB512 gene in the same mouse strain. Inspection of amino acid sequences of the CDR3 of idiotypic positive and negative clones suggested that idiotypic structures may be associated with the expression of Tyr at position 95 and Phe or Leu at position 96 in the H and L chains, respectively. Therefore the indiscriminate use of idiotypic markers to characterize VH genes and the relevance of idiotypic regulation in VH gene expression are questioned. Id-positive and Id-negative clones displayed similar affinity values for dextran, indicating that idiotypic and binding structures were probably separated. The exchange of Asp65 for Gly65 in one of the clones reduced affinity for dextran, suggesting the involvement of CDR2 in dextran binding. The dominant expression of VH genes can be explained by somatic and/or genetic mechanisms. Because somatic mechanisms such as idiotypic regulation or selection based on affinity for dextran did not seem to influence the expression of the VHB512 gene we favor a genetic alternative. We discuss a model based on the distance between VH genes and D and JH elements. This model is compatible with somatic and genetic regulation in other systems and provides a new theoretical approach to the understanding of immune VH dominance and low responsiveness.

Animals↗

PubMed1992

The NZB mouse as a model for chronic lymphocytic leukemia.

Chronic lymphocytic leukemia (CLL) is the most common leukemia in the Western world and the only leukemia for which a possible genetic component has been described. Analysis of this genetic component has been hindered by the fact that disease onset normally occurs after age 50. We report here the aged NZB mouse as an animal model for CLL. NZB mice have a genetically regulated, age-dependent onset of clonal, aneuploid cells which are IgM+ and Ly1+ (CD5+ B-cells). Peripheral blood smears from old NZB mice show an increase in circulating lymphocytes and "smudged" or ruptured cells, often seen in human CLL. Electron microscopic examination of these cells shows them to be mature lymphocytes. Light microscopy of the spleen shows infiltration of small lymphocytes and is consistent with CLL pathology. These long-lived, CLL-like cells can be serially passaged into recipient animals. This continued passage occasionally results in the development of a large cell lymphoma detectable in the spleen, lymph nodes, and liver. The histology of this lymphoma is quite distinct from that of the CLL-like cells, but the phenotype is that of an aneuploid CD5+, IgM+ cells. This apparently represents a continued transformation of the CLL-like clone similar to the development of Richter's syndrome in human CLL. Therefore, the NZB mouse can be a valuable tool for the determination of the genetic basis of CLL ontogeny and the conversion of CLL into Richter's syndrome.

Age Factors↗

PubMed1992

Female Syrian hamster Harderian gland: development and effects of high environmental temperature and melatonin injections on histology and porphyrin deposits.

We have investigated the development of the Harderian glands of female Syrian hamsters from birth to 8 months of age. The effects of melatonin injections on Harderian gland histology and porphyrin deposits of female hamsters exposed to two different temperatures were also studied. The morphology of the Harderian glands from 30-day-old female hamsters resembled those of sexually mature adult animals. The intraluminal area occupied by porphyrins increased significantly between 20 to 30 days of age. However, the relative number of mast cells per mm2 rose between 30 to 90 days. Both porphyrins and mast cell numbers appeared clearly reduced in the 8-month-old group. Secretory cells characterized by large lipid droplets (type II cells) were not observed. Daily afternoon injections of 25 micrograms of melatonin to female hamsters exposed to 22 degrees C for 14 weeks resulted in the discontinuity of estrous cyclicity, a marked decrease in the intraluminal area occupied by porphyrins, a reduction of the number of mast cells per mm2, and in a marked augmentation of the number of type II cells per mm2. Although the administration of similar dosages of melatonin to hamsters exposed to an environmental temperature of 32 degrees C did not interrupt estrous cycles, a clear reduction of the area occupied by porphyrins was observed. However, the number of mast cells and type II cells per mm2 was unaffected in these animals. Our results suggest that hormones other than ovarian steroids are involved in the regulation of the female hamster Harderian glands. The possible role of melatonin on Harderian gland metabolism is discussed.

Animals↗

PubMed1992

Specificity of oligonucleotide probes complementary to evolutionarily variable regions of 16S rRNA from Mycoplasma hyopneumoniae and Mycoplasma hyorhinis.

Mycoplasma is the common name for the smallest free-living microorganisms, the Mollicutes. Mycoplasma hyopneumoniae is of great importance in veterinary medicine, causing enzootic pneumonia in pigs. M hyorhinis can cause polyserositis and may cause pneumonia in piglets. Oligonucleotides complementary to variable regions of 16S rRNA from these mycoplasmas were designed and used as probes for detection and identification of these mycoplasmas. The probe complementary to 16S rRNA of M hyorhinis gave a very weak cross-hybridisation with M hyosynoviae in filter hybridisation experiments, but not with any of the other porcine mycoplasmas tested. Three oligonucleotide probes complementary to M hyopneumoniae 16S rRNA were tested. One of the probes (Mhp6/30) was found to be specific to M hyopneumoniae, but the other two gave cross-hybridisation with M flocculare. Using the Mhp6/30 probe in direct filter hybridisation experiments, it proved possible to detect M hyopneumoniae in lung biopsies from experimentally infected pigs.

Animals↗

PubMed1992

[L-carnitine in the treatment of chronic myocardial ischemia. An analysis of 3 multicenter studies and a bibliographic review].

The authors selected, from a general sample of 3525 cardiopathic patients treated with 2 g daily of L-carnitine during 1 year, 220 stable effort angina TNT-responder patients, presenting more than 15 anginal episodes per month; moreover, other 59 anginal patients in congestive heart failure have been taken into account. The evaluation of the results obtained in these samples has been done in parallel with the ones of cardiopathic patients studied in 2 multicentric trials carried out, according to a very similar protocol, in Switzerland (148 patients treated at the same posology for 6 months) and Germany (143 patients, 3 months of treatment). The analysis of the three trials showed net reduction of both rate of anginal episodes and therapeutic use of nitrates, substantiated by improvement of physical performance (demonstrated by ergometric test in the German trial) as well as of the quality of life (the Swiss trial). Furthermore, from the general sample of 3525 patients the authors selected 737 subjects with clearly pathological levels of plasma cholesterol, in order to evaluate the effect of L-carnitine treatment on lipidemic parameters; after 12 months of administration only 282 patients showed abnormal levels of cholesterolemia. Analysis of the results of the three trials and a review of the literature on carnitine identify the compound as a fundamental drug for the treatment of patients with myocardial ischemia.

Angina Pectoris↗

PubMed1992

B cell surface marker analysis of synovial fluid cells in a patient with monoarthritis and chronic lymphocytic leukemia.

We describe a women with clinically quiescent chronic lymphocytic leukemia who developed monoarthritis consistent with her known diagnosis of osteoarthritis. Because of the concurrent chronic leukemia, we were concerned with the possibility of leukemic arthritis. Immunofluorescence of synovial fluid cells demonstrated an increase in B cells that failed to demonstrate monoclonality as determined by light chain class expression. However, biopsy of synovial tissue revealed leukemic infiltration. Local radiation therapy resolved the monoarthritis.

Aged↗

PubMed1991

Determination of zopiclone enantiomers in plasma by liquid chromatography using a chiral cellulose carbamate column.

The enantiomers of zopiclone were determined in human plasma using a sequential achiral-chiral liquid chromatographic method. Zopiclone was separated from the biological matrix and quantified on an achiral silica column. The limit of detection was 5 ng/ml. The eluent fraction containing zopiclone was collected, evaporated, reconstituted with the mobile phase and injected onto a chiral cellulose carbamate column where the enantiomeric ratio was calculated. This validated method, applied to a pilot study, suggests that pharmacokinetics of zopiclone is stereoselective.

Azabicyclo Compounds↗

PubMed1991

Anesthetic dependence of the inhibitory effect of neurotensin on pentagastrin-stimulated acid secretion in rats. A possible role for somatostatin.

The existence of possible local mediators of the inhibitory effect of neurotensin on gastric acid secretion has not been determined. We perfused rats intragastrically with warmed saline and stimulated acid secretion with intravenous pentagastrin, 32 micrograms/kg/hr, and found that anesthesia with pentobarbital resulted in marked inhibition of acid secretion by intravenous neurotensin; however, anesthesia with urethane prevented this inhibitory effect of neurotensin from occurring. In addition, we found a significant increase in somatostatin-like immunoreactivity in portal venous blood during neurotensin infusion in pentobarbital-anesthetized rats. Neither neurotensin nor pentagastrin infusion modified gastric luminal somatostatin-like immunoreactivity after either pentobarbital or urethane, and rats anesthetized with urethane did not show an increase of somatostatin-like immunoreactivity in portal venous blood during neurotensin infusion. These results suggested that somatostatin-like immunoreactivity, released into the portal circulation, was necessary for exogenous neurotensin to inhibit pentagastrin-stimulated gastric acid secretion under these conditions in anesthetized rats.

Anesthesia, General↗

PubMed1991

The influence of T cells on the immunoglobulin repertoire and the affinity maturation of the immune response against dextran B512 in C57BL/6 mice.

A collection of hybridomas from C57BL/6 mice producing antibodies to dextran B512 was analysed and found to reflect the immune response in vivo with regard to immunoglobulin class expression, T cell dependency and antibody affinity. IgM-, IgG-3, and IgG-2b, and IgA-producing hybridomas were found. IgG3-producing hybridomas were obtained from nude mice, indicating T cell independent IgG3 synthesis. All monoclonal antibodies were of kappa light chain. A major anti-dextran idiotype was expressed in many monoclonals. Secondary immune responses to dextran were also suppressed at the hybridoma cell level. However, hybridomas from secondary responses produced antibodies expressing the major idiotype, suggesting that anti-idiotype mediated suppression was not responsible for the reduced secondary response. Most monoclonals belonged to the VHJ558 family, but the IgG3-producing hybridomas showed a preferential use of genes from the VHX24 family. All monoclonals were directed against internal structures of the dextran molecule. The affinity for dextran of the IgG antibodies produced in secondary immune responses was drastically increased, even when the mice were immunized with thymus-independent forms of dextran, indicating that T helper cells need not be involved in affinity maturation of the immune response.

Animals↗

PubMed1991

Chronic administration of melatonin induces changes in porphyrins and in the histology of male and female hamster harderian gland: interrelation with the gonadal status.

In this paper, we have investigated the influence of melatonin on the histology and porphyrin content of the Syrian hamster Harderian glands. Daily afternoon injections of 25 micrograms of melatonin to female hamsters for 12 weeks resulted in the discontinuity of estrous cyclicity, a marked decrease in the Harderian gland intraluminal area occupied by porphyrins, and in a significant rise in the number of Type II cells. A similar decrease in porphyrins was observed after 8 weeks of ovariectomy. However, if the melatonin injections were given for only 8 weeks (without inducing gonadal atrophy), no changes were observed in the area occupied by intraluminal porphyrins, suggesting that the effects of melatonin in female Syrian hamsters might be associated with the subsequent gonadal atrophy. Castration of male hamsters induced a significant increase in porphyrins and a clear drop in the number of Type II cells. These changes were totally prevented when melatonin was administered daily from the day of castration. Our results suggest that melatonin, at least in male Syrian hamsters, plays a role in Harderian metabolism, acting directly on the Harderian secretory cells or indirectly through pituitary hormones.

Animals↗

PubMed1990

A randomized study of two vindesine plus cisplatin-containing regimens with the addition of mitomycin C or ifosfamide in patients with advanced non-small cell lung cancer.

The current trial was carried out to assess the survival enhancement achieved, if any, by adding ifosfamide to vindesine and cisplatin (IVP) in contrast to mitomycin plus vindesine and cisplatin (MVP). Between June 1986 and September 1988, 110 patients were randomly allocated to receive either ifosfamide (3 g/m2 plus 3 g/m2 of mesna) or mitomycin 8 mg/m2, on days 1, 29, and 71 only. In both arms vindesine was given 3 mg/m2 weekly X 5 then every 2 weeks. In the MVP arm, 120 mg/m2 of cisplatin was administered on days 1 and 29 and then every 6 weeks, whereas in the IVP arm 100 mg/m2 of cisplatin was given on the same time schedule. One hundred three patients were evaluable for response and toxicity and 56% of patients had Mountain's Stage IV disease. The response rate was 26% (14/53 patients) in the MVP arm (95% confidence interval, 14%-39%) and 20% (ten of 50 patients) in the IVP arm (95% confidence interval, 10%-34%). Neither the response rate nor the median survival times were significantly different, although more nephrotoxicity was produced in the MVP arm, grade 1+ in 43% versus 26% in IVP arm (P = 0.04). Results obtained from this study fail to demonstrate that mitomycin or ifosfamide have a synergistic effect on the efficacy of the vindesine/cisplatin combination.

Adult↗

PubMed1990

Induction of germ-line immunoglobulin heavy chain transcripts by mitogens and interleukins prior to switch recombination.

It has recently been postulated that immunoglobulin class switching is preceded by transcription from unrearranged heavy chain genes. In this report, we have investigated the conditions under which RNA transcribed from unrearranged C gamma 3, C gamma 1, C gamma 2b, C gamma 2a, C epsilon and C alpha genes are induced in normal spleen cells by mitogens and/or interleukin (IL) 4, IL 5 and interferon-gamma. Lipopolysaccharide (LPS) plus IL 4 induced germ-line gamma 1 and epsilon transcripts. LPS induced gamma 2b and gamma 3 transcripts and high doses of IL 4 suppressed these LPS-induced transcripts. Interferon-gamma induced low levels of germ-line gamma 2a transcripts and profoundly suppressed the gamma 1 and epsilon transcripts induced by LPS and IL 4. IL 5 alone or in combination with IL 4 and/or LPS did not induce germ-line alpha transcripts. Spleen cells of the partially immunodeficient mice CBA/N and C3H/HeJ, which do not express IgG3 could be induced, however, by polyclonal activators to express germ-line gamma 3 and gamma 2b transcripts. The data indicate that the capacity of a ligand to induce/suppress transcription of a particular unrearranged heavy chain gene is a good indicator of its capacity to induce switching to the corresponding Ig isotype. However, it is also clear that control of switching can be carried out at other levels.

Animals↗

PubMed1990

Serum antibody and cellular immune response in mice to dextran B512.

Serum antibodies to dextran started to appear 3 days after immunization of C57BL/6 mice. Synthesis of IgM antibodies was followed by IgG3 and IgGA. Other immunoglobulin classes (IgG1, IgG2b, and IgG2a) were very low or absent. The immune response to dextran was also thymus independent with regard to IgG3 and IgA synthesis as demonstrated by the use of nu/nu mice. CBA and C57BL/6 mice were high responders to dextran with regard to IgM synthesis. C57BL/6 mice produced high levels of IgG3 and IgA antibodies, whereas CBA, A/J, and A.TL only synthesized IgM antibodies. A/J and A.TL strains were most frequently low responders with regard to IgM synthesis and CBA/N mice were completely nonresponders with regard to all immunoglobulin classes. The ability to produce anti-dextran antibodies increased with age in high responder strains. This was most pronounced for IgG3 and IgA antibodies, which reached adult levels 3 months after birth. The affinity of anti-dextran antibodies was high and homogeneous in antisera from C57BL/6 mice. Preimmune matural antibodies and antibodies from immunized low responder strains had a low and variable affinity for dextran.

Aging↗

PubMed1989

Giant-cell tumor of bone, stage II, displaying translocation t(12;19)(q13;q13).

A new case of giant-cell tumour (GCT) of bone with benign histological features, clinical stage II, has been reviewed with immunohistochemistry and electron microscopy. After short-term tissue culture the karyotype, using G-banding techniques, presented a consistent translocation t(12;19)(q13;q13). Nude mice xenografts of the tumour were unsuccessful after 6 months of follow-up. Presence of such chromosomal rearrangement may be related to locally aggressive, histologically benign giant-cell tumors of bone.

Adult↗

PubMed1989

Biliary excretion and choleretic effect of cefmetazole in rats.

The effect of cefmetazole, a broad-spectrum cephalosporin, on bile flow and composition in rats was studied. Intravenous injection of cefmetazole at doses ranging from 40 to 400 mumol/kg of body weight led to an increase in its biliary concentration and excretion rate, with a maximum at 30 min after injection. Excretion of cefmetazole into bile was associated with a marked choleresis. The magnitude of the increase in bile flow was dose dependent, with a maximal increase at a dose of 200 mumol/kg. Cefmetazole administration did not affect the secretion of bile acids or their osmotic activities, whereas the bile acid-independent bile flow increased by 49% at a dose of 200 mumol/kg. Cefmetazole administration at a dose of 200 mumol/kg significantly increased the biliary outputs of sodium, potassium, chloride, and bicarbonate (+36, +56, +28, and +31%, respectively) compared with outputs of controls. A linear relationship was observed between bile flow and cefmetazole excretion, 44 microliters of bile being produced per mumol of cefmetazole excreted into bile. Our results demonstrate that cefmetazole induces choleresis by stimulating bile acid-independent bile flow. This effect appears to be partly due to the osmotic properties of cefmetazole transported into bile.

Animals↗

PubMed1989

Quality of life during chemotherapy in non-small cell lung cancer patients.

To evaluate the usefulness of chemotherapy in non-small cell lung cancer, objective response, length of remission and survival have been considered the main yardsticks. Subjective improvement and gain in Karnofsky performance status have attracted very little attention. Thirty-one patients with stages III and IV underwent combination chemotherapy with high-dose cisplatin, and were assessed with categorical scales and 100 mm visual analogue scales used by patients themselves to report on several symptoms of their illness. After chemotherapy 17 of 19 patients (89%) gained weight; 20 presented anorexia, 10 of those (50%) improved; 15 had pain, 7 of those (47%) were alleviated; cough was reported in 22, in 10 (45%) it was ameliorated; hemoptysis disappeared in 10 of 11 patients (91%); of the 9 patients who had dyspnea, 7 improved (78%); and astenia was attenuated in 8 of 16 patients (50%). Quality of life was reported improved in 75% of those patients who had considered themselves seriously affected prior to the treatment. When compared with Karnofsky performance status, no relationship was found (r = 0.31). It is concluded that, apart from the objective response achieved, a significant proportion of patients did benefit from treatment as demonstrated by a marked relief of symptoms.

Antineoplastic Agents↗

PubMed1988

Plasma and urinary heparin cofactor II levels in patients with nephrotic syndrome.

Heparin cofactor II (HC II) levels were measured by electroimmunoassay in plasmas and urines from 68 patients with nephrotic syndrome. In addition, antithrombin III (AT III) and protein C (PC) activities and antigens were measured also in the same group of patients. Seven of these patients had histories of thrombosis. Plasma HC II levels (mean +/- SD 105 +/- 43) were not different from levels in healthy subjects (94 +/- 17). Only 5 patients had low plasma levels of HC II. None of the patients with thrombosis had low HC II levels. Even though measurable amounts of HC II were found in 25 urines from 50 patients. There was a relationship in the urinary excretion between HC II and AT III and their urinary clearances were quite similar. However, no correlation was found between plasma HC II and AT III levels, and levels of AT III activity and antigen were significantly lower than in healthy subjects. Three patients with histories of thrombosis had low AT III levels. Most patients (including those with thrombosis histories) had high plasma PC levels and increased urinary loss. It is suggested that HC II does not play an important role in the pathogenesis of thrombosis in nephrotic syndrome.

Adolescent↗

PubMed1988

Evidence for central entrainment of the medullary respiratory pattern by the locomotor pattern in the rabbit.

1) Although periodic passive hindlimb movements can reproduce the enhancement of breathing frequency seen at the onset of muscular exercise, we have shown previously that they were unable to induce the 1:1 coupling which is observed between locomotion and respiration during galloping in quadrupeds. The purpose of this study was to investigate the existence of a central coupling in two experimental situations: first, decorticate - DOPA, and secondly, decerebrate rabbit preparations. 2) After DOPA administration in curarized, vagotomized, decorticate animals, an absolute coordination could be observed between the locomotor bursts (which developed in hindlimb muscle nerves) and phrenic activity. With the temporal evolution of the pharmacological activation, the coupling mode varied from 1:1 to 1:2 during the same experiment with a loss of coordination between these two forms. When the coordination between both motor activities was not produced in such conditions, it could be induced for some imposed frequencies of periodic passive motions applied to the contralateral hindlimb. 3) When the DOPA effects were completely over, a rostro-pontine decerebration allowed locomotor activity to be released and a tight 1:1 coupling could be obtained again between the two motor patterns in this new experimental situation. 4) An analysis of the data revealed that the various forms of coordination obtained in the different experimental situations are due to a central resetting of the respiratory and of the locomotor patterns. The capability of the hindlimb proprioceptive inputs to coordinate locomotor and respiratory patterns in the decorticate-DOPA preparation appeared simply linked to their ability to entrain the activity of the lumbar locomotion generator. It is suggested that these central reciprocal interactions, which have the properties of an entrainment process, are the result of interactions between the lumbar locomotion generator and the medullary respiratory one.

Action Potentials↗