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Biomedical subjects

J Martin

Publications and source records attributed to J Martin.

At least 739 records · Page 41Linked to original sources
PubMed1988

Cardiovascular effects and modulation of noradrenergic neurotransmission following central and peripheral administration of neuropeptide Y.

Experiments have been conducted to evaluate the effect of neuropeptide Y (NPY) administered at three distinct levels of the nervous system: 1) the posterior hypothalamic nucleus, 2) the spinal cord, and 3) the vascular noradrenergic neuroeffector junction. It was observed that NPY produced varying cardiovascular effects at these three distinct sites of the nervous system. Microinjections into the posterior hypothalamic nucleus resulted in an increase in blood pressure, which was reduced by prior microinjection of a muscarinic or H1-histamine antagonist but not an H2-histamine antagonist. In addition to the involvement of histaminergic and cholinergic pathways, the pressor effect of NPY appears to result from an increase in sympathetic outflow. NPY was also seen to decrease the potassium-induced release of norepinephrine (NE) from slices obtained from the posterior hypothalamic nucleus. In contrast to what was observed in the hypothalamus, the intrathecal injection of NPY at a level of T4 or T10 in anesthetized or T10 in unanesthetized rats resulted in a depressor effect as well as a decrease in heart rate. Both an alpha 2- and beta-adrenoceptor antagonist reduced the NPY effect. The depressor effect of intrathecal NPY was attenuated in rats pretreated with reserpine as well as in Spontaneously Hypertensive rats (SHR). These data suggest that the effects of NPY are closely associated with sympathetic preganglionic neurons in the spinal cord. At the vascular noradrenergic neuroeffector junction, NPY decreased the nerve stimulation-induced release of NE while potentiating the contractile response. Moreover, NPY potentiated the increase in perfusion pressure of the perfused mesenteric arterial bed in response to angiotensin, vasopressin, or phenylephrine.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Comparative study of the effects of acebutolol, atenolol, d-propranolol and dl,-propranolol on the alterations in energy metabolism caused by ischemia and reperfusion: a 31P NMR study on the isolated rat heart.

31-P NMR spectroscopy data recorded for the isolated heart were analyzed, in conjunction with functional and biochemical variables, in order to investigate the effect observed for several different beta-adrenoceptor antagonists or the alterations provoked by global partial ischemia (37 degrees C, 24 minutes, 1% residual coronary flow) and reperfusion in the metabolism of the myocardium. During ischemia: intracellular acidosis, adenosine triphosphate (ATP) degradation, and inorganic phosphate (Pi) accumulation were found to be reduced whether the perfusion fluid contained: acebutolol 2.7 x 10(-5) M, atenolol 10(-5) M, d-propranolol 10(-5) M, or dl-propranolol 10(-5) M. On reperfusion metabolic and functional variables were variously affected by the different drugs, except the Pi level which was, in all series, significantly lower compared with control hearts. The adenylate charge and the glycogen stores were protected in the acebutolol, dl-propranolol, and d-propranolol groups. The ATP level was higher than in controls only in the acebutolol and atenolol groups. The intracellular pH recovered to values nonsignificantly different from preischemic values in the acebutolol and dl-propranolol-treated hearts only. The mechanical performance, expressed as the rate-pressure product, was unaltered by the ischemia-reperfusion sequence in the acebutolol and d-propranolol series, while decreasing significantly in controls and in the atenolol group. In dl-propranolol-treated hearts the mechanical activity, which in normoxic conditions was already halved during the effect of the drug, remained at this same level after ischemia. From these observations, it appears that the nonspecific properties of the drugs, as distinct from beta-blockade, play an important part in attenuating the ischemia-induced alteration in myocardial metabolism. Thus, it can be postulated that (1) the metabolic effects of dl-propranolol probably result largely from the reduction of heart work induced by this drug; (2) the maintenance of energy metabolism associated with the preservation of the myocardial activity, as observed in the case of acebutolol and d-propranolol, is possibly a consequence of the existence of a membrane-stabilizing activity.

Acebutolol↗
PubMed1988

Heat resistance, immunological and quantitative changes of neutrophil alkaline phosphatase in trisomy 21 pregnancies.

Neutrophil alkaline phosphatase (NAP) was analysed in 25 pregnant women with trisomy 21 foetuses whose chromosomal aberration was recognized by cytogenetic study after amniocentesis. Enzyme investigation was performed at 20-22 weeks of gestation using cytochemical and biochemical techniques. Twenty-nine women at the same stage of normal pregnancies were selected as controls. In parallel, each mother was karyotyped. Ten subjects from each series underwent biochemical and immunological investigation: measurement of enzyme levels, thermostability study and immunological tests with alkaline phosphatase isoenzyme antibodies. NAP from pregnant women with trisomy 21 foetuses was characterized by: (1) a lower rate of enzyme activity, (2) a large amount of heat-stable enzyme (T = 56 degrees C for biochemical assays, T = 85 degrees C for cytochemical tests), and (3) a marked loss of liver antigenicity. These findings suggest the presence in trisomy 21 pregnancies of a non-specific alkaline phosphatase isoenzyme which appears as an "enzyme marker" in maternal circulating neutrophils.

Adult↗
PubMed1988

Discrepancies in serological tissue typing revealed by DNA techniques.

DNA techniques were applied to typing a population of renal patients in order to assess the number of discrepancies between this technique and the serological technique. Five patients had been given an incorrect type by serology, and in 22 instances allogenotypes were found where previously there had been a serological blank. DNA typing was also able to determine allogenotypic subtypes that correlated with DR antigens difficult to split by serology and to determine allogenotypic subtypes correlating with DR antigens not known to have a split by serology. Whereas DNA typing provided a result first time of testing on all but 3 patients, the average number of serological testings for each patient was 1.9.

DNA↗
PubMed1988

Laboratory diagnosis of Mycoplasma pneumoniae infection. 1. Direct detection of antigen in respiratory exudates by enzyme immunoassay.

Direct and indirect antigen capture enzyme immunoassays (Ag-EIA) have been developed for the detection of Mycoplasma pneumoniae in nasopharyngeal aspirates or sputum from respiratory infection. The sensitivity of the two Ag-EIA were similar, but the indirect method using polyclonal rabbit and guinea-pig antisera was more convenient. The Ag-EIA had a detection limit of 10(4-4.5) colony-forming units/ml of sample. It was specific for M. pneumoniae and gave a low level response with M. genitalium. There were no cross-reactions with 10 other species of mycoplasmas. Tests with a wide range of bacteria and chlamydia group antigen, representing agents sometimes found in the respiratory tract, were also negative. At the current level of development, the Ag-EIA detected about 90% of specimens that were also positive for culture; 43% of specimens from culture-negative--seropositive patients gave a positive result. The overall pattern of results indicated that while antigen detection is a quick and effective substitute for the slow culture method, serological examination for specific IgM antibody is also necessary to give a complete diagnostic coverage.

Antibody Specificity↗
PubMed1988

Laboratory diagnosis of Mycoplasma pneumoniae infection. 2. Comparison of methods for the direct detection of specific antigen or nucleic acid sequences in respiratory exudates.

The efficiency of the direct detection of Mycoplasma pneumoniae in respiratory exudates by an antigen capture, indirect enzyme immunoassay (Ag-EIA), has been compared with its detection with a cDNA probe ('Gen-Probe assay') directed against the specific ribosomal RNA sequences of the organism ('Mycoplasma pneumoniae Rapid Diagnostic System', Gen-Probe, San Diego, California). Both assays showed excellent specificity against a range of mycoplasma species suspended in negative nasopharyngeal aspirates; only M. pneumoniae and M. genitalium reacted. In experiments with graded doses of viable M. pneumoniae cells suspended in negative nasopharyngeal aspirate, the Gen-Probe assay was more sensitive than Ag-EIA; detection limits were respectively 2 X 10(3) c.f.u./ml (3.2 X 10(5) genomes) and 2.5 X 10(4) c.f.u./ml (4 X 10(6) genomes); detection levels 10-100 times less sensitive than culture. The two assays were also tested on nasopharyngeal aspirates or sputum specimens from 90 patients with respiratory infection; 67 of these were culture- or seronegative for M. pneumoniae and 23 were culture- or seropositive. Ag-EIA detected 21 (91%) of the latter but the Gen-Probe assay detected only 5 (22%). Both assays were negative with the 67 culture-/sero-negatives; there were no Gen-Probe assay positive/Ag-EIA negatives. Overall, it is concluded that although Ag-EIA and the Gen-Probe assay are effective substitutes for culture as a diagnostic procedure, there is a significant problem with samples which are culture-negative and from patients who have good serological evidence of current infection. Possible reasons for the disparity between the two assays are advanced.

Antigens, Bacterial↗
PubMed1988

In-vitro assessment of lomefloxacin (SC-47111)--a new quinolone derivative.

The activity of lomefloxacin (SC-47111) was studied in vitro against 500 clinical isolates. Comparison was made with enoxacin and ciprofloxacin. Lomefloxacin was comparable in activity to enoxacin, but less active than ciprofloxacin. Most Gram-negative bacilli were susceptible, including several multi-resistant strains. Pseudomonas aeruginosa showed variable susceptibility. Streptococci, including Streptococcus pneumoniae, were generally the least susceptible organisms.

Anti-Bacterial Agents↗
PubMed1988

Optimization of a rapid test by using fluorescein-conjugated monoclonal antibodies for detection of Chlamydia trachomatis in clinical specimens.

A mixture of two fluorescein isothiocyanate-conjugated monoclonal antibodies (MAbs) was used to optimize a direct specimen test (Chlamydia Direct Specimen Test IF; Clonatec, Paris, France) for detection of chlamydial elementary bodies in clinical specimens. One MAb reacted with a subspecies-specific epitope of the major outer membrane protein (molecular weight 43,000) of Chlamydia trachomatis, whereas the other reacted with the periodate-sensitive genus-specific antigen (molecular weight 11,000) of Chlamydia spp. Nonfat dry milk was the most efficient additive at suppressing the fluorescent background and was included in the antibody preparation. Fc-dependent binding of fluorescein-conjugated MAbs to protein A-containing Staphylococcus aureus was inhibited by addition of purified rabbit immunoglobulin. The Chlamydia Direct Specimen Test IF was compared with tissue culture isolation by using 309 genital specimens. The sensitivity and specificity were 77.4 and 98%, respectively.

Animals↗
PubMed1988

Isolated pulmonary histiocytosis.

Pulmonary disease in the 'histiocytosis syndromes' is not uncommon. Isolated pulmonary histiocytosis, however, is rarely diagnosed. We describe three patients with this condition, with ages ranging from 3 weeks to 9 1/2 years, in whom there was no evidence of disease in any other organ. Their presentation, treatment, and clinical progress over three years of follow up are discussed.

Child↗
PubMed1988

An enzymatic marker in mothers of trisomy 21 children: neutrophil alkaline phosphatase.

Neutrophil alkaline phosphatase (NAP) from 12 mothers of normal children was investigated and the results compared to those of 7 mothers with trisomy 21 offsprings, in an attempt to determine a parental molecular change in this chromosomal abnormality. The biochemical properties of the enzyme were analyzed by the procedures of isoenzyme characterization, i.e. enzyme assays, thermostability, inhibition patterns and slab gel electrophoresis. Immunological properties were determined on 5 samples from normal mothers and on the same sample number of mothers with affected children. In these latter NAP showed characteristics that were to some extent different from the ones of normal controls. The following changes were observed: highly significant loading of membrane and nucleus pellets in NAP activity, poor effect of inhibitors on thermostable component and immunodepletion measured by a significant decrease of the normal affinity for antiliver and antiplacental alkaline phosphatase antisera. These findings are discussed in the light of our knowledge of alkaline phosphatase isoenzymes.

Adult↗
PubMed1988

Hemodynamics in humans during conventional and experimental methods of cardiopulmonary resuscitation.

High-fidelity hemodynamic recordings of aortic and right atrial pressures and the coronary perfusion gradient (the difference between aortic and atrial pressure) were made in nine patients during cardiopulmonary resuscitation (CPR). Findings during conventional manual CPR were compared with those during high-impulse CPR (rate, 120 cycles/min with a shorter compression:relaxation ratio) as well as during pneumatic vest CPR with and without simultaneous ventilation and abdominal binding. Aortic peak pressure during conventional CPR averaged 61 +/- 29 mm Hg but varied widely (range, 39-126 mm Hg) among patients. Although the magnitude of improvement was modest, the high-impulse method was the only technique tested that significantly elevated both aortic peak pressure and the coronary perfusion gradient during cardiac arrest. During conventional CPR, aortic pressure rose from 61 +/- 29 to 80 +/- 39 mm Hg during high-impulse CPR, and the gradient rose from 9 +/- 11 to 14 +/- 15 mm Hg, respectively; p less than 0.01. The pneumatic vest method significantly improved peak aortic pressure but not the coronary perfusion gradient. Simultaneous ventilation and chest compression created high end-expiratory pressure and lowered the coronary perfusion gradient. Abdominal binding had no significant hemodynamic effects. This evaluation of experimental resuscitation methods in humans shows that the high-impulse chest compression method augments aortic pressure over levels achieved during conventional CPR methods; however, the improvement in pressure is modest and may not be clinically important. Simultaneous ventilation as well as abdominal binding during CPR were associated with no benefit; in fact, simultaneous ventilation appears to adversely affect cardiac perfusion and, therefore, should not be used during clinical resuscitation.

Aorta↗