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Biomedical subjects

C Martin

Publications and source records attributed to C Martin.

At least 829 records · Page 46Linked to original sources
PubMed1989

Comparison of two methods of bacteriologic sampling of the lower respiratory tract: a study in ventilated patients with nosocomial bronchopneumonia.

The purpose of this prospective study was to compare the results of bacteriologic assessment of the lower respiratory tract in mechanically ventilated patients by two sampling techniques: fiberoptic protected brush biopsy or blind bronchial aspiration of secretions. Thirty-three mechanically ventilated patients with acute bronchopneumonia were studied. Paired samples were collected by both techniques 47 times. Identical results were obtained in 93% of the cases. In 28 pairs, one or several identical organisms were cultured. In 16 pairs, no bacteria were isolated; in the three remaining pairs, results were contradictory. In five patients with concomitant positive blood cultures, the same organisms were cultured from fiberoptic protected brush biopsy, blind bronchial sampling, and blood cultures. These findings support the fact that blind bronchial sampling can be recommended for bacteriologic assessment of the lower respiratory tract in mechanically ventilated patients with diffuse nosocomial bronchopneumonia.

Biopsy↗
PubMed1989

Phagocyte-pathogen in the infected host.

Phagocytosis is a major mechanism of defense against bacterial infections. The ingestion of different microorganisms by blood granulocytes or monocytes may involve a variety of cell membrane recognition structures (e.g., immunoglobulin or complement receptors, lectin-like structures or other nonspecific binding sites). It is of interest to know which mechanism plays a prominent role in the management of a particular type of infection. Forty-three pathogenic bacterial suspensions were obtained from patients under mechanical ventilation at the onset of nosocomial lower respiratory tract infections. They were coincubated with blood granulocytes from the same or other patients in the presence or absence of the corresponding serum. Phagocytosis and the oxidative burst were then assayed. We conclude the following: a) Substantial phagocytosis was found under serum-free conditions and the patients' sera did not dramatically enhance bacterial uptake during the first days after the onset of clinical symptoms. b) The phagocytes from an infected patient did not display any peculiar inability to bind to the bacteria that grew successfully in this subject. Hence, the occurrence of a particular infection might be dependent on a defect of intracellular killing of ingested pathogens or on the conditions of infection development.

Adult↗
PubMed1989

Comparison of four severity scores in patients with head trauma.

This study examines the performance of four severity scores in a group of 70 consecutive patients with head trauma, hospitalized in the same neurosurgical ICU. On day of admission to the ICU, data were collected from each patient to compute Acute Physiology Score (APS), Simplified Acute Physiology Score (SAPS), Glasgow Coma Scale (GCS), and Therapeutic Intervention Scoring System (TISS). These four scores were statistically correlated with the outcome of patients. Results also indicate that GCS was superior to any other score in predicting outcome of patients and allowed better specificity and sensitivity. Regarding the level of care needed by patients, TISS was superior to any other scoring system. The difficulty in estimating individual prognosis is discussed, since scoring systems are aimed at classifying groups of patients, not individuals. It is concluded that GCS is a simpler and less time consuming method in predicting outcome of patients with head trauma.

Adolescent↗
PubMed1989

Genetic interactions underlying flower color patterns in Antirrhinum majus.

Diverse spatial patterns of flower color in Antirrhinum can be produced by a series of alleles of pallida, a gene encoding an enzyme required for pigment biosynthesis. The alleles arose by imprecise excision of a transposable element, Tam3, and we show that they carry a series of deletions involving progressive removal of sequences adjacent to the excision site. This has enabled us to define three cis-acting upstream regions, A, B, and C, which differentially affect the level of pallida expression in distinct areas of the flower. We show further that an unlinked locus, delila, regulates the spatial distribution of pallida transcript. Deletion of regions ABC at the pallida locus uncouples pallida from regulation by delila, whereas deletion of A or AB brings pallida under regulation by delila in a new area of the flower. These results suggest that diverse patterns of pallida expression reflect the different ways in which alleles interact with a prepattern of both common and spatially specific genetic signals in the flower.

Alleles↗
PubMed1989

Caffeine-induced inhibition of calcium channel current in cultured smooth cells from pregnant rat myometrium.

1. The inhibitory effect of caffeine on the calcium channel current was investigated in cultured myometrial cells isolated from pregnant rats. 2. Caffeine inhibited the calcium channel current elicited from a holding potential of -70 mV in a concentration-dependent manner. The IC50 was estimated to be 35 mM. 3. The caffeine inhibition was not enhanced when calcium channels were opened by a conditioning depolarizing pulse sequence or when the number of inactivated calcium channels was increased at depolarized holding potentials. 4. Caffeine antagonized the specific binding of (+)-[3H]-isradipine to myometrial membranes. The IC50 value found in binding experiments was similar to the IC50 value for half-maximal inhibition of calcium channel current. Caffeine decreased the maximal binding capacity of (+)-[3H]-isradipine to myometrial membranes without any significant change in the dissociation constant. 5. The results indicate that caffeine interacts with a site closely associated with the voltage-dependent calcium channels in myometrial cells and, in turn, inhibits calcium influx.

Animals↗
PubMed1989

Effects of variation of inverted-repeat sequences on reactions mediated by the transposase of Tn21.

The frequencies of one-ended transposition and normal transposition of derivatives of Tn21 that contain mutant inverted-repeat sequences (IRs) have been measured. In general, there was a linear relationship between the log of the frequency of one-ended transposition of a mutant IR and the log of the frequency of normal transposition of an element flanked by a wild-type IR at one end and by the mutant IR at the other. This implied that one-ended and normal transposition share the rate-limiting step that determines the frequency of transposition and that both IRs are involved in the rate-limiting step in normal transposition. Surprisingly, it was found that only the outer 18 base pairs of the IR of Tn21 engaged accurately in both one-ended and normal transposition, at about 1% of the frequency of the wild-type IR.

Base Sequence↗
PubMed1989

KEX2 mutations suppress RNA polymerase II mutants and alter the temperature range of yeast cell growth.

Suppressors of a temperature-sensitive RNA polymerase II mutation were isolated to identify proteins that interact with RNA polymerase II in yeast cells. Ten independently isolated extragenic mutations that suppressed the temperature-sensitive mutation rpb1-1 and produced a cold-sensitive phenotype were all found to be alleles of a single gene, SRB1. An SRB1 partial deletion mutant was further investigated and found to exhibit several pleiotropic phenotypes. These included suppression of numerous temperature-sensitive RNA polymerase II mutations, alteration of the temperature growth range of cells containing wild-type RNA polymerase, and sterility of cells of alpha mating type. The ability of SRB1 mutations to suppress the temperature-sensitive phenotype of RNA polymerase II mutants did not extend to other temperature-sensitive mutants investigated. Isolation of the SRB1 gene revealed that SRB1 is KEX2. These results indicate that the KEX2 protease, whose only known substrates are hormone precursors, can have an important influence on RNA polymerase II and the temperature-dependent growth properties of yeast cells.

Blotting, Western↗
PubMed1989

An ATP-sensitive conductance in cultured smooth muscle cells from pregnant rat myometrium.

The whole cell voltage-clamp technique was used to study the effects of extracellular ATP in cultured smooth muscle cells isolated from pregnant rat myometrium. An inward current was elicited by ATP (IATP) in cells held at -70 mV under voltage clamp. The amplitude of IATP was reduced by estrogen pretreatment and by the end of pregnancy. IATP not only did not undergo any desensitization but showed facilitation. The current-voltage relationship of IATP was linear and reversed close to 0 mV. Changing the sodium electrochemical gradient by decreasing extracellular or intracellular sodium resulted in a linear relationship between the reversal potential of IATP and Na equilibrium potential that, however, differed from the predicted curve for a purely sodium conductance. The conductance activated by ATP was monovalent cation selective with little discrimination between potassium, cesium, and sodium ions. IATP was depressed by divalent cations, and the rank order of potency was Co greater than Mg greater than Ca greater than Ba, suggesting that the free-acid form of ATP was the effective ligand. Adenosine, AMP, and ADP were ineffective in eliciting IATP, whereas ATP gamma S and alpha,beta-methylene ATP were capable of mimicking the effects of ATP, although they were less potent. These results are consistent with the free-acid form of ATP activating a monovalent cation-selective and estrogen-sensitive conductance in myometrium.

Adenine Nucleotides↗
PubMed1989

Calcium channel currents in isolated smooth muscle cells from human bronchus.

An electrophysiological study was carried out on smooth muscle cells that were enzymatically dissociated from bundles of muscle fibers dissected out of human bronchi obtained at thoracotomy. These cells that retain the contractile properties of intact bundles were voltage-clamped by means of the whole-cell patch-clamp technique. Upon voltage steps from a holding potential of -60 mV to more positive levels, the initial inward current was followed by large outward currents that inactivated slowly. These were subsequently reduced by substituting Cs+ for K+ in the internal solution and by using Ba2+ instead of Ca2+ as a charge carrier in the external solution. Under these conditions, the inward current did not completely inactivate in the course of 300-ms voltage steps. Inward current measured after leak subtraction was activated at a membrane potential of -25.8 +/- 5 mV, was maximum at +18 +/- 4 mV, and had an apparent reversal potential of +52.5 +/- 5.5 mV (n = 5). The potential at which steady-state inactivation was half-maximum was -28 mV (n = 5). This inward current was identified as a calcium current on the following basis: 1) it was not altered by 10 microM tetrodotoxin (TTX) or by lowering to 10 mM external Na+ concentration; 2) it was blocked by 2.5 mM Co2+ or 1 microM PN 200-110; 3) it was enhanced by 1 microM BAY K 8644, which in addition suppressed the PN 200-110 blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Bronchi↗
PubMed1989

The psychiatric emergency service holding area: effect on utilization of inpatient resources.

This study compared the rates of hospitalization from two psychiatric emergency services which were similar except that one service had an extended evaluation unit, or holding area, allowing up to 24 hours of evaluation. The rate of hospitalization from the service with the extended evaluation unit was 36%; the rate from the other service was 52%. The difference in admission rates was related to the availability of the extended evaluation unit, which made it possible for many patients to avoid rather than merely postpone admission to the hospital. Clinical determinants of admission and of successful treatment in the unit were also reviewed.

Adolescent↗
PubMed1989

[Surgery of otospongiosis in the elderly].

This paper only deals with patients suffering from otosclerosis, operated upon by stapes footplate piston procedure. We have been using this technique since 1963 and described it in 1966 stressing on the necessity of performing an accurately cut and circular footplate orifice, perfectly calibrated to the prosthesis diameter. The patients are considered as elderly if they are 70 or more, the oldest one was 84. Always performed under local anesthetic with a practically bloodless field, this surgery never induced any general complication. The patient gets up the day after surgery. Amongst 5,000 cases operated on by the same otologist between 1963 and 1987, 5.5% were 70 or more, 0.5% 80 or more. The immediate results are the same as in the younger patients for the majority frequencies and seems even better later on for the 4,000 Hz frequency. Also, the late bone conduction threshold in often much better than the preoperative one. So, we believe that all otosclerosis in the elderly can be operated on using our surgical procedure.

Age Factors↗
PubMed1989

[Endoscopy and cophosurgery].

Certain fixed adherent retraction pockets especially in the posterior aspect of the tympanic cavity and certain cholesteatomas are difficult to treat even after a posterior tympanotomy has been performed. Using 70 degrees and especially 30 degrees optical systems can be of great value as the lesions can be perfectly visualised and endoscopic copho-surgery itself can even be carried out. Study of 27 cases of fixed retraction pockets and 14 cholesteatomas which underwent microscopic surgery but with optical verification of the operative cavity demonstrated the value of this technique. The safety of the method even allows the exclusive use of the endaural route in cases which have up to now required a posterior approach and posterior tympanotomy.

Cholesteatoma↗