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C Martin

Publications and source records attributed to C Martin.

At least 739 records · Page 41Linked to original sources
PubMed1991

Horizontal transfer of multiple penicillin-binding protein genes, and capsular biosynthetic genes, in natural populations of Streptococcus pneumoniae.

Multiply antibiotic-resistant serotype 23F isolates of Streptococcus pneumoniae are prevalent in Spain and have also been recovered recently in the United Kingdom and the United States. Analysis of populations of these isolates by multilocus enzyme electrophoresis, and restriction endonuclease cleavage electrophoretic profiling of penicillin-binding protein (PBP) genes, has demonstrated that these isolates are a single clone (Muñoz et al., 1991). Here we report studies of non-serotype 23F penicillin-resistant pneumococci isolated in Spain and the United Kingdom. One of the isolates expressed serotype 19 capsule but was otherwise indistinguishable from the serotype 23F clone on the basis of multilocus enzyme electrophoresis, antibiotic resistance profiling, and restriction endonuclease patterns of genes encoding PBP1A, PBP2B and PBP2X, a result which suggests that horizontal transfer of capsular biosynthesis genes had occurred. These same techniques revealed that six other resistant isolates, all expressing serotype 9 polysaccharide capsule, represent a clone. Interestingly, the chromosomal lineage of this clone is not closely related to the 23F clone; however, the serotype 9 and 23F clones harbour apparently identical PBP1A, -2B and -2X genes. To explain these data, we favour the interpretation that horizontal gene transfer in natural populations has distributed genes encoding altered forms of PBP1A, -2B and -2X to distinct evolutionary lineages of S. pneumoniae.

Alleles↗
PubMed1991

Control of anthocyanin biosynthesis in flowers of Antirrhinum majus.

The intensity and pattern of anthocyanin biosynthesis in Antirrhinum flowers is controlled by several genes. We have isolated six cDNA clones encoding enzymes in the pathway committed to flavonoid biosynthesis and used these to assay how the regulatory genes that modify colour pattern affect the expression of biosynthetic genes. The biosynthetic genes of the later part of the pathway appear to be co-ordinately regulated by two genes, Delila (Del), and Eluta (El), while the early steps (which also lead to flavone synthesis) are controlled differently. This division of control is not the same as control of anthocyanin biosynthesis by the regulatory genes R (S) and C1 in maize aleurone, and may result from the adaptive significance of different flavonoids in flowers and seeds, reflecting their attractiveness to insects and mammals respectively. El and del are probably involved in transcriptional control and both genes appear to be able to repress expression of some biosynthetic genes and activate expression of others.

Anthocyanins↗
PubMed1991

Pharmacokinetics and tissue penetration of a single 1,000-milligram, intravenous dose of metronidazole for antibiotic prophylaxis of colorectal surgery.

The levels of metronidazole in serum and tissue penetration of metronidazole were studied after prophylactic administration in 11 patients undergoing elective colorectal surgery. A single dose of 1,000 mg given intravenously was administered before surgery. Adequate drug levels in serum (greater than or equal to MIC for 90% of strains tested [MIC90] for Bacteroides fragilis) were found in all patients throughout the procedure. Mean peak (15-min) and last-determined (24-h) metronidazole levels in serum were 28.8 +/- 8 and 4.2 +/- 1.7 mg/liter, respectively. The beta-phase elimination half-life was 9.5 +/- 2.3 h, and the clearance and apparent volume of distribution were 57 +/- 13 ml/min and 0.7 +/- 0.1 liter/kg, respectively. In the colonic wall at surgical anastomosis, tissue metronidazole levels greater than or equal to MIC90 for B. fragilis were found in 91% of patients. In the abdominal wall fat and epiploic fat, tissue metronidazole levels greater than or equal to MIC90 for B. fragilis were found in 40 to 60% of patients at surgical incision and closure. No anaerobic infection occurred during the study.

Aged↗
PubMed1991

Ofloxacin pharmacokinetics in mechanically ventilated patients.

The pharmacokinetics of ofloxacin were studied in 12 intensive care patients, 6 of whom were under controlled mechanical ventilation. All patients had a creatinine clearance of greater than 80 ml/min per 1.73 m2. They were given 3 mg of ofloxacin per kg of body weight intravenously at a constant flow rate in 30 min twice a day for 7 days. Pharmacokinetic studies were performed on days 1 and 7. Between days 1 and 7, significant increases in the alpha (distribution) and beta (elimination) phase half-lives, the area under the serum concentration-time curve, and peak and trough levels in serum were observed, together with a marked decrease (greater than 50%) in total body clearance. Possible contributing factors for alteration of ofloxacin pharmacokinetics in ventilated patients were patient age, liver dysfunction, drug interaction, and drug accumulation in a deep compartment. This study shows that in intensive care patients the pharmacokinetics of ofloxacin differ from those reported for healthy volunteers.

Critical Care↗
PubMed1991

Sequence analysis of the clpG gene, which codes for surface antigen CS31A subunit: evidence of an evolutionary relationship between CS31A, K88, and F41 subunit genes.

The clpG gene coding for the CS31A subunit was localized on a 0.9-kb SphI fragment from the recombinant plasmid pAG315. This was established by testing the ability of subclones to hybridize with a 17-meric oligonucleotide probe obtained from N-terminal analysis of the CS31A subunit. The nucleotide sequence of the region coding for CS31A was determined. From primer extension analysis, two initiation translation start sites were detected. Two possible promoterlike sequences were identified; the ribosome binding site and the translation terminator are proposed. Inverted repeat sequences leading to the formation of possible hairpin structures of the transcripts were found on the 5' untranslated region of clpG. The deduced amino acid composition was in close agreement with the chemical amino acid composition and sequence match with the first 25 N-terminal amino acids from the published N-terminal sequence of the purified CS31A subunit. The clpG gene codes for a mature protein of 257 amino acids with a molecular size of 26,777 Da. An obvious homology was observed when the amino acid sequence of CS31A was compared with those of K88 and F41. This homology includes five different conserved sequences of up to 19 identical amino acids, which is associated with conserved proline. An extensive change in the CS31A region homologous to that identified to contain the K88 receptor binding site might be responsible for the functional divergence between CS31A and K88.

Amino Acid Sequence↗
PubMed1991

Successful xenogeneic transplantation in embryos: induction of tolerance by extrathymic chick tissue grafted into quail.

In previous experiments, we have demonstrated that limb buds engrafted during embryonic life at E4, between MHC-mismatched chick embryos, are not only tolerated after birth, but induce in the recipient a state of split tolerance toward cells expressing the donor MHC haplotype: donor's skin grafts are permanently tolerated while a proliferative response of host's T cells is generated in MLR by donor-type blood cells. If the same experiment is performed, using quail embryo as a donor and chick as a recipient, acute rejection of the quail limb starts during the first two weeks after birth, thus suggesting that the peripheral type of tolerance induced in these experiments can be obtained only in allogeneic but not in xenogeneic combinations. We report here the unexpected result that when a chick limb bud is grafted into a quail at E4, it is tolerated and, like allogeneic grafts in chickens, induces adult skin-graft tolerance without modifying the MLR response. Similar results were obtained with grafts from another closely related species of bird, the guinea fowl from the Phasianidae family. In contrast, xenogeneic combinations involving more distant species (chick and quail as recipients and duck, an Anatidae, as donor) resulted in strong and early rejection from both recipients. As a whole, quails exhibit a greater ability than the chick to become tolerant to antigens presented peripherally from early developmental stages. In adult quails, however, skin grafts performed in either direction (i.e., quail to chick or the reverse) are rejected according to a similar temporal pattern. Moreover, lymphocytes of both species are able to respond equally well to quail or chick IL-2. Several hypotheses are envisaged to account for these observations. It seems likely that this type of tolerance is directly related to antigenic load because the load in chick to quail wing chimeras is larger than that in quail to chick chimeras. This view is supported by the protracted delay in graft rejection observed when two quail wing buds instead of one are grafted into chickens.

Animals↗
PubMed1991

Lipolytic and ketogenic fluxes in human hyperthyroidism.

The effect of hyperthyroidism on lipolytic and ketogenic fluxes was determined by measuring simultaneously (stable isotope methodology) glycerol, nonesterified fatty acids (NEFA), and ketone body (KB) kinetics in euthyroid and hyperthyroid subjects. In the postabsorptive state hyperthyroid patients had normal concentrations of insulin and glucagon, but increased concentrations (P less than 0.01) and turnover rates (P less than 0.01) of glycerol, NEFA, and KB. The ratio of NEFA appearance rate to glycerol appearance rate was decreased in hyperthyroid subjects (2.34 +/- 0.23 vs. 3.15 +/- 0.22; P less than 0.05), indicating that intracellular cycling between triglycerides and fatty acids was increased. The percentage of NEFA flux used for KB production, calculated from NEFA disappearance rates and KB appearance rates, was increased in hyperthyroid patients (21.20 +/- 2.75% vs. 13.37 +/- 0.63%; P less than 0.05), suggesting a diversion during hyperthyroidism of hepatic fatty acid metabolism toward ketogenesis. However, when the plasma NEFA levels of control subjects were raised by the infusion of a triglyceride emulsion to levels comparable to those observed in hyperthyroid patients their percentage of NEFA flux used for ketogenesis rose to values slightly higher (26.30%) than those of hyperthyroid subjects. In conclusion, 1) hyperthyroidism results not only in increased lipolysis, but also in enhanced triglyceride-fatty acid cycling, which could contribute to the excessive energy expenditure; and 2) the increased KB production of hyperthyroid patients results more from an increase in NEFA availability than from a direct stimulation of hepatic ketogenesis.

Adult↗
PubMed1991

Haemopoietic phagocytes in the early differentiating avian retina.

The existence of specialised phagocytic cells is described in regions of the retinal neuroepithelium undergoing intense cell death during early differentiation of the avian embryo retina (2.5-5 days of incubation). These results were obtained using routine techniques for light microscopy, acid phosphatase histochemistry and immunocytochemical staining with antibodies MB-1 and QH-1, both specific for quail endothelial cells and all blood cells except mature erythrocytes. Specialised phagocytes were distinguishable from neuroepithelial cells on the basis of morphological criteria: in the former, the nucleus was not oval in shape and was not oriented perpendicular to basement membrane neuroepithelium. The cytoplasm of the specialised phagocytes was often filled with dead cell fragments. In contrast to neuroepithelial cells, the specialised phagocytes showed acid phosphatase activity and were labelled with both MB-1 and QH-1 antibodies in normal quail embryos and chick----quail yolk sac chimeras. Moreover, some acid phosphatase positive and MB-1/QH-1 positive cells also appeared in the presumptive vitreous body, at the edges of the optic cup and in the surrounding mesenchyme. As the vitreal cells and the specialised phagocytes of the neural retina were immunolabelled in chick----quail yolk sac chimeras, we conclude that they are derived from haemopoietic cells in the yolk sac. Some images suggest that these cells enter the vitreous body from the surrounding mesenchyme and traverse the basement membrane of the neuroepithelium in the optic disc region to give rise to the specialised phagocytes of the retinal neuroepithelium.

Acid Phosphatase↗
PubMed1991

[Facial motricity of trigeminal origin. Apropos of a typical case and review of the literature].

The authors report the case of a patient who underwent the neurosurgical exeresis of an acoustic neuroma 14 years ago, and subsequently presented with a total facial palsy in spite of a spinofacial anastomosis. This patient had to be reoperated because of tumoral recurrence compressing the trigeminal nerve (V). This operation, through atranslabyrinthic that also emptied the entire internal auditory canal of its neural elements, allowed removing the neuroma. Once the facial nerve had been resected, the patient recovered some facial motricity and his masticatory function improved on the day following the operation. Since the contralateral facial nerve was not involved and the spinofacial anastomosis was absolutely not functional, only motor reinnervation from the trigeminal nerve was possible. The anatomy of the facial and trigeminal nerves in summarized, and their central connexions and peripheral anastomoses are studied. Out of the 27 cases of spontaneous motor reinnervation following the resection of the facial nerve described in the literature, only one similar case of recovery of motricity after a major nerve resection in the cerebellopontine angle is reported. Such a phenomenon can be explained only by the transformation of some sensory fibers of the 5th cranial nerve into motor fibers, which are activated by the resection of the 7th nerve and receive their nervous influx from the motor nucleus of the 5th or 7th nerve through protuberantial communications.

Facial Nerve↗
PubMed1991

[Diagnostic and surgical strategy in sporadic primary hyperparathyroidism].

The generalized use of phosphocalcic biological assays makes the discovery of sporadic primary hyperparathyroidism increasingly common. In 1989-1990, first-intention surgery was performed in 26 female patients. In all cases, an exploratory cervicotomy under cervical peridural anesthesia allowed discovering and treating a parathyroid lesion: adenoma, asymmetric or symmetric hyperplasia, cancer. We discuss: the circumstances of the clinical diagnosis and the biological criteria, the timeliness of preoperative radiological assessment, the surgical strategy advocated. In more than 90% of all cases, a cervicotomy for the exploration of all areas of parathyroid migration should allow curing primary hyperparathyroidism.

Adenoma↗
PubMed1991

The natural history of suspected scaphoid fractures.

Clinically suspected scaphoid fractures are common injuries. The authors prospectively followed up, by serial radiography and bone scanning, 23 patients who had a history of trauma to the carpus and associated localized tenderness to the anatomic "snuff box": in 15 patients the radiographs and bone scans were negative; in 5 the radiograph was equivocal and the bone scan positive. The authors concluded that patients with clinically suspected scaphoid fractures and negative radiographs can be treated symptomatically without immobilization in a cast. Patients with equivocal radiographs should be assumed to have a fractured scaphoid and treated accordingly.

Adolescent↗
PubMed1991

[Pharmacokinetics and tissue penetration of single-dose netilmicin used for antibiotic prophylaxis during colo-rectal surgery].

Pharmacokinetics and tissue penetration of netilmicin were studied after the use of a single dose (6 mg/kg) given for antibioprophylaxis in colo-rectal surgery. Thirteen patients, scheduled for elective surgery, were given 6 mg/kg IV netilmicin over 30 min, together with 1000 mg IV ornidazole. Netilmicin peak serum concentration (10 min after end of infusion) was 24.4 +/- 3.4 mg/l and trough level (24 h) was 0.9 +/- 0.5 mg/l. Plasma elimination half-life was 409 +/- 70 min, le volume apparent volume of distribution was 38 +/- 101 and total body clearance was 0.07 +/- 0.02 ml/min. Adequate netilmicin levels (5 greater than or equal to CMI 90 of involved pathogens Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus) were obtained in 100 per cent of patients in abdominal wall and epiploid fat, at time of opening, and in colonic wall at time of anastomosis. Adequate levels were obtained at time of closure in abdominal wall and epiploid fat in 92 to 100 per cent of patients. In situation of allergy to beta-lactam antibiotics, the use of netilmicin in combination with ornidazole may be recommended.

Aged↗
PubMed1991

[Diffusion of ciprofloxacin into bronchial secretions in mechanically ventilated patients].

The aim of the study was to evaluate, in clinical conditions, the penetration of ciprofloxacin into bronchial secretions. Eight patients were included in the study. They presented with nosocomial pneumonia and were under controlled mechanical ventilation. Ciprofloxacin was given at a dose of 3 mg/kg over 30 min. Serial bronchial and blood samples were obtained over a 12 hour period on day 2 and 4. Ciprofloxacin was measured by HPLC. Serum peak levels were 2.95 +/- 1 mg/l on day 2, and 2.43 +/- 0.7 mg/l on day 4. Bronchial peak and through levels were 0.95 +/- 0.51 mg/l and 0.21 +/- 0.12 mg/l, respectively, on day 2, and 0.76 +/- 0.17 mg/l and 0.18 +/- 0.14 mg/l, respectively, on day 4. The ratio of bronchial/serum peak was 0.32 +/- 0.11 and 0.33 +/- 0.06 on day 2 and 4, respectively. The ratio of AUC 0-12 h in the bronchial secretions/AUC 0-12 h in the serum samples was 0.66 +/- 0.04 and 0.55 +/- 0.27 on day 2 and 4, respectively.

Aged↗
PubMed1991

[Menière's disease. A psychosomatic disease?].

Although psychosomatic aspects of Meniere's disease have already been pointed out by some authors, few papers have been publisched on this question. 48 patients suffering from Meniere's disease underwent in addition of a complete audiological examination a psychosomatic study using two psychometric auto evaluation tests. It appears that patients suffering from Meniere's disease have a significantly different psychopathologic personality than normals (anxiety, depressive tendency, phobia). Besides, an obvious correlation is found between deafness, vertigo's recurrences and psychopathological disorders. These findings must be taken into consideration to treat patients suffering from Meniere'es disease.

Ambulatory Care↗
PubMed1991

[Stapes decompression].

Footplate decompression, which has been described in Lyon in 1965, can be easily performed under local anesthesia. The surgical procedure consists of a 8/10 mm diameter stapedotomy followed by an obturation with spongel, gelfoam or a piece of thin fascia. The operation is not a labyrinthectomy or a sacculotomy but aims to decompress endolymphatic hydrops in Ménière's disease. It must be realised only in case of typical unilateral Ménière's disease with disabling vertigo and very poor residual hearing. More than two hundred cases have been operated on. Vertigo has been relieved in 90% of the operated cases, tinnitus less severe in 50% of cases and hearing sometimes worse but often unchanged. In patients suffering from a unilateral Ménière's disease with disabling vertigo and poor residual hearing, footplate decompression appears to be one of the most simple safe and effective surgical procedures.

Humans↗