Biomedical subjects
Publications and source records attributed to J Peters.
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To assess left ventricular (LV) diastolic function in children with systemic hypertension, 11 patients with hypertension (mean blood pressure 99 mm Hg) and 7 normal patients (mean blood pressure 78 mm Hg) underwent M-mode echocardiography and pulsed Doppler examination of the LV inflow. From a digitized trace of the LV endocardium and a simultaneous phonocardiogram, echocardiographic diastolic time intervals, peak rate of increase in LV dimension (dD/dt), and dD/dt normalized for LV end-diastolic dimension (dD/dt/D) were measured. Doppler diastolic time intervals, peak velocities at rapid filling (E velocity) and atrial contraction (A velocity), and the ratio of E and A velocities were measured. The following areas under the Doppler curve and their percent of the total area were determined: first 33% of diastole (0.33 area), first 50% of diastole, triangle under the A velocity (A area), and the triangle under the E velocity (E area). The A velocity (patients with hypertension = 0.68 +/- 0.11 m/s, normal subjects = 0.49 +/- 0.08 m/s), the 0.33 area/total area (patients with hypertension = 0.49 +/- 0.09, normal subjects = 0.58 +/- 0.08), the A area (patients with hypertension = 0.17 +/- 0.05, normal subjects = 0.12 +/- 0.03), and the A area/total area (patients with hypertension = 0.30 +/- 0.11, normal subjects = 0.20 +/- 0.07) were significantly different between groups (p less than 0.05). M-mode and Doppler time intervals, (dD/dt)/D, E velocity, and the remaining Doppler areas were not significantly different between groups.(ABSTRACT TRUNCATED AT 250 WORDS)
The effect of oral diltiazem treatment on the mean ventricular rate was studied in 10 patients with stable atrial fibrillation (AF). The profile of mean ventricular rate was analyzed by means of 24-hour electrocardiographic recordings. Both single-dose (120 mg) and maintenance therapy (80 mg 3 times daily) reduced the mean ventricular rate significantly. After the single dose, the effect set in after 120 +/- 40 minutes (mean +/- standard deviation) and persisted for 347 +/- 84 minutes. Histograms of RR intervals were plotted and their changes after diltiazem therapy were also analyzed. The shortest and longest atrioventricular (AV) conduction times were defined as 5% and 95% values of the cumulative frequency curve, respectively. There were 2 distinct types of the RR-interval histographic changes: In 50% of the patients, the longest and shortest RR intervals prolonged proportionately; in the other 50%, the longest intervals increased disproportionately. Results indicate that oral diltiazem treatment can significantly decrease the mean ventricular rate in patients with AF by influencing the concealed conduction in the AV node. The changes of the RR-interval histograms suggest that in 50% of the patients, the increase of the concealed conduction was probably caused primarily by the increase of AF rate, and in 50% both increased AF rate and prolonged refractory period in the AV node contributed to the increase of concealed conduction.
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Tracheal and alveolar gas composition was studied by mass spectrometry in a patient with severe ARDS treated by low frequency positive pressure ventilation/extracorporeal CO2-removal (LFPPV-ECCO2R). Measured alveolar gas concentrations were compared with values derived from standard respiratory equations. As a result we found that during LFPPV-ECCO2R with a constant endotracheal O2-flow, alveolar gas composition cannot be predicted reliably from standard equations. The reasons for this finding are discussed. We conclude that monitoring of alveolar gas composition by mass spectrometry is of great value during LFPPV-ECCO2R if PAO2, P(A-a)O2 and Qva/Qt are to be determined correctly.
An electrophoretically detectable variant of lactate dehydrogenase-2 in Mus musculus has been found and used to locate the structural gene, Ldh-2, on chromosome 6. Gene order and recombination frequencies are estimated as Sig--36.0 +/- 4.8--Lc 21.0 +/- 4.1--Miwh--20.0 +/- 4.0--Ldh-2.
Anomalous course of the left innominate vein beneath the aortic arch is a rare congenital anomaly. We report the case of a 3 year old child in whom this defect was detected by two-dimensional and Doppler echocardiography. The echocardiographic appearance of the anomalous course of the left innominate vein is illustrated and the importance of identifying this rare systemic venous anomaly is discussed.
Serum total carotenoid (STC) and vitamin A levels were done as part of the biochemical screening in comparative studies of lipid lowering agents in type Ila hyperlipoproteinemic patients. STC levels were reduced following bile acid sequestering agent administration (colestipol 30 g/d) by 30% (P less than 0.01). Clofibrate and avicel placebo had inconsistent and nonsignificant effects on the STC levels. Serum vitamin A levels were not significantly altered by any of the test agents. The STC level changes were not correlated with concomitant changes in low-density lipoprotein-cholesterol (LDL-C) during any of the treatment regimens. It is suggested that STC level changes are related to alterations in the absorption of carotenoids during bile acid sequestrant administration.
Hypoxemia during hemodialysis may result from several differing processes. We initially studied patients undergoing standard acetate hemodialysis. At 15 minutes of dialysis, leukopenia (primarily neutropenia), a decline of platelet count, and hypoxemia occurred, but without a significant change in mean minute ventilation. Complement activation (V/A ratios of C5a greater than 1.0) persisted throughout dialysis. Leukocyte count returned to baseline by one hour. To separate the effects of solute and/or gas fluxes from those of blood-membrane interaction we studied changes in Po2, WBC, C5a, TxB2, and PGI2 during a period of blood membrane interaction without dialysis, and during subsequent acetate dialysis. Patients were studied with both polyacrylonitrile (PAN) and cuprophan membranes containing different priming solutions during membrane contact alone. Despite leukopenia and complement activation, hypoxemia failed to occur during membrane contact alone. At 15 minutes of subsequent acetate dialysis, significant hypoxemia occurred with both membranes. However, the degree of hypoxemia was twice as great with a cuprophan membrane primed with acetate (18.6 +/- 3.3 mm Hg) compared with air or bicarbonate (9.1 +/- 1.4 and 7.0 +/- 2.0 mm Hg, respectively), or compared with PAN (8 +/- 2.8 mm Hg). Changes in thromboxane B2, PGI2, and C5a did not correlate with changes in Po2. We conclude that there are two major components to dialysis related hypoxemia. One is membrane independent, and may relate to the metabolic effects of acetate or to dialyzer CO2 loss. The remaining portion is membrane dependent, occurring with cuprophan, but not with PAN, and is conditioned by an acetate dependent interaction between blood and membrane.
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A mutation induced by ethylnitrosourea in a spermatogonial stem cell of a 101/H mouse has resulted in a structurally altered beta-diffuse major globin in one of his offspring. The mutant hemoglobin is associated with polycythemia, rubor, increased oxygen affinity and decreased hem-hem interaction. The mutant haplotype has been designated Hbbd4, polycythemia. Amino acid analysis of the mutant globin has shown that a single substitution beta 145 Tyr----Cys has occurred, and it is proposed that ethylnitrosourea induced an A----G transition in the tyrosine codon (TAC----TGC). This murine polycythemia is homologous with hemoglobin Rainier in man, in which the amino acid substitution is also beta 145 Tyr----Cys and which is associated with similar physiological consequences.
We have studied the effects of the TRH related dipeptide histidyl-proline diketopiperazine [cyclo (His-Pro)] on basal and stimulated TSH and PRL secretion in normal volunteers, in patients with microprolactinomas and in patients with primary hypothyroidism. Cyclo (His-Pro), 400 micrograms intravenously did not alter basal TSH or PRL levels in normal males and females and was also without effect upon the elevated basal TSH and PRL levels in patients with primary hypothyroidism and microprolactinomas respectively. The same dose of cyclo (His-Pro) did not affect the TSH or PRL response to TRH (100 micrograms i.v.) in normal male volunteers. These data indicate that cyclo (His-Pro) does not affect TSH and PRL secretion in man at this dosage. It is also unlikely that this molecule will be of any therapeutic benefit in states of hyperprolactinaemia.
The susceptibility of 3 laboratory strains and 24 clinical isolates of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) to 5-ethyl-2'-deoxyuridine was determined in plaque reduction assays in Vero cells. The median effective doses were 8.6 and 7.8 microM, respectively. The drug was less potent than acyclovir and other related antiviral drugs, but it had a high therapeutic index against both HSV-1 and HSV-2. Drug-resistant viruses were readily produced in cell culture. These variants were cross-resistant to acyclovir, 2'-fluoro-5-iodoaracytosine, and 2'-fluoro-5-methylarauracil but were susceptible to vidarabine or phosphonoformate. These findings confirm that the selective antiviral activity of 5-ethyl-2'-deoxyuridine is mediated by the virus-induced thymidine kinase. Oral or intraperitoneal administration of the drug at nontoxic doses was ineffective in protecting mice against intracerebral challenge with virus. Using implanted osmotic minipumps or coadministering the drug with dimethyl sulfoxide failed to decrease the mortality rate. In guinea pigs infected genitally with HSV-2, topical drug treatment was more effective than placebo in reducing lesion severity and other clinical and virological variables. These effects were noted whether the drug treatment was initiated 3 or 24 h after infection (ascertained serologically). Drug-treated animals had a significantly lower herpes antibody titer than did placebo-treated guinea pigs, suggesting that the drug can also reduce the viral antigen load. In this model, the drug appeared to be as effective as topical phosphonoformate or acyclovir.
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The anaesthesiologist is faced with a growing number of patients in need of cardiac pacing with systems of increasing complexity. This includes patients seen for de novo pacemaker implantation, patients with permanent pacemakers in place or patients requiring temporary pacing as an emergency or after cardiac surgery. This review article is intended to provide the anaesthesiologist with the information necessary to evaluate and treat such patients. Emphasis is laid on haemodynamic problems and possible pacemaker failure due to electromagnetic interference.
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