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Biomedical subjects

M Moser

Publications and source records attributed to M Moser.

At least 271 records · Page 15Linked to original sources
PubMed1990

Antihypertensive medications: relative effectiveness and adverse reactions.

Thiazide diuretics may be more effective as antihypertensive agents in many subsets of patients than other medications, especially in reducing systolic blood pressure. Angiotensin converting enzyme (ACE) inhibitors and beta-blockers are less effective than calcium blockers or diuretics in black hypertensives and beta-blockers may be less effective in the elderly. Calcium blockers are equally effective in blacks, whites and the elderly but may not be as efficacious as diuretics. When used as initial monotherapy, most available antihypertensive drugs produce significant adverse subjective effects in about 8-10% of patients; centrally acting drugs, however, may produce annoying side effects in 20-30% of patients. Usually, some medication can be found that lowers blood pressure and is acceptable to the patient. Adverse metabolic effects are probably of limited long-term clinical significance except in a few patients. An approach to therapy that will prove effective in a majority of patients is outlined. Any one of the four classes of agents may appropriately be used as initial monotherapy (diuretics, beta-blockers, ACE inhibitors, calcium blockers). Diuretics are recommended as the second drug of choice if one of the other agents is used first. With this approach approximately 80% or more of patients can be controlled at normotensive levels on one or at most two drugs.

Adrenergic beta-Antagonists↗
PubMed1990

Methods in clinical hemorheology: the continuous measurement of arterial blood density and blood sound speed in man.

Both blood density and sound speed are closely related to total protein concentration in blood and, as a consequence, to rheologically important parameters of blood. Two methods that permit continuous measurement of these properties, the mechanical oscillator technique and the new ultrasonic technique, were used for measuring blood protein concentration over a continuous period of time in a group of hemodialysis patients and in volunteers. It was seen that the concentration of the components of blood varies considerably. This variability is related to transport phenomena within as well as to the flow of masses across the cardiovascular compartment. From the continuous measurement of concentrations during hemodialysis treatment, relative changes in blood volume can be recorded in order to control the fluid balance of the patient. Rapid fluctuations at the macroscopic scale with periods of 5 to 30 seconds are due to heterogeneities at the microscopic scale and to the particular rheological behaviour of the red blood cells at the level of the capillaries and the small blood vessels. The amplitude of rapid oscillations increased up to 1.2% in terms of hematocrit values when there was rhythmic, spontaneous breathing at various frequencies. The measurement of concentrations at an accessible measuring site may be used to investigate the rheology of blood in the human microvasculature.

Blood Flow Velocity↗
PubMed1990

Controversies in the management of hypertension.

Despite recent controversies in hypertension management, family physicians can confidently follow a straightforward diagnostic and treatment approach. Routine use of echocardiography or 24-hour ambulatory monitoring is not recommended in the initial work-up of hypertension. The optimum goal for the diastolic blood pressure remains at 80 to 85 mm Hg. As many as 20 to 25 percent of patients with mild hypertension become normotensive with dietary modifications, exercise and alcohol cessation. In patients with mild hypertension, these nonpharmacologic approaches should be tried for three to six months before drug therapy is instituted. Initial drug therapy should be chosen on the basis of effectiveness, ease of administration, tolerability, cost and long-term safety record. Many of the reported adverse metabolic effects of diuretics may be of limited clinical significance. Despite the availability of newer antihypertensives, diuretics remain a choice in most patients as initial therapy or as a step-2 drug.

Adrenergic beta-Antagonists↗
PubMed1990

Adaptation of an introduced host to an indigenous parasite.

Introduction of striped bass to the west coast from the east coast of the U.S.A. provided the opportunity to study a recent host-parasite association in a marine system. An indigenous species of parasite was known to induce pathological changes in the introduced population. Because the west coast population has been in association with this pathogenic parasite more than 20 generations, we predicted that the host reaction of the west coast population would be less severe compared to that of the naive east coast stock of striped bass. This prediction was tested by conducting reciprocal infection experiments with east and west coast hosts and parasites. The group of west coast striped bass had a lower intensity of infection and exhibited less tissue damage compared to the group of east coast striped bass. We suggest that selection has acted only on the host and is driven by parasite-induced host mortality. This type of 1-sided selection is in contrast to present models of the evolution of host-parasite associations.

Animals↗
PubMed1990

Recurrent sinusitis and impairment of eustachian tube function in air passengers and crew.

Chronic and recurrent sinusitis, and thus impaired tubular function, are usually caused by isolated lesions of the ethmoid cells. Purulent nasal secretions are transported over the openings of the tubes into the epipharynx. Inflammation and swelling of the mucosa of the tube openings causes stenosis or blockage. Inflammatory foci, usually hidden in the anterior ethmoid cell system, are not always apparent in a plain film of the paranasal sinuses. They appear only in a computed-tomography scan or in a conventional tomogram. Once the diagnosis has been made, a simple, guided endoscopic procedure suffices to alleviate a stenosis, open inflamed ethmoid cells, and restitute ventilation of the nasal sinuses and, thus, tubal function. Radical procedures on the maxillary and frontal sinuses, and plastic operations on deviated nasal septa (which impair the function of the nose and the nasal sinuses only in extreme cases), are thus often unnecessary. Septum deviations are irrelevant to the fitness-to-fly of air personnel as long as the tube and the ventilation of the sinuses function freely. The Valsalva maneuver with otoscopic visualization of the excursion of the eardrum is the most reliable test of tubal function. Tympanometry is used mainly for documentation.

Acoustic Impedance Tests↗
PubMed1990

Fitness of civil aviation passengers to fly after ear surgery.

Movements of the tympanic membrane caused by changes in air pressure are conducted to the ossicles of the middle ear. The gliding mechanism of the malleus-incus articulation converts in-and-out movements of the eardrum into up-and-down movements of the stapes, thereby protecting the inner ear from static pressures. In certain ear operations, the replacement of a middle ear ossicle by a prosthesis disjoints the malleus-incus articulation or makes it rigid. Pressure is then transmitted in unattenuated form from the eardrum through the oval window to the inner ear. Impairment of pressure equilibration, for example due to obstructed eustachian tubes, can lead to prosthesis displacement with severe injury to the vestibulocochlear apparatus. Thus, patients should be advised to begin equilibration of pressure at the beginning of descent of commercial airlines or civil aviation flights, and to repeat it a brief intervals.

Acoustic Impedance Tests↗
PubMed1989

Differential inhibitory action of the fungal toxin orellanine on alkaline phosphatase isoenzymes.

The inhibitory action of orellanine (3,3',4,4'-tetrahydroxy-2,2'-dipyridyl-1,1'-dioxide), a fungal toxin of Cortinarius orellanus Fr. and C. orellanoides R. Hry., on alkaline phosphatase isoenzymes was studied. Orellanine specifically inhibited alkaline phosphatase activity in LLC-PK1 renal epithelial cell cultures and in the colon carcinoma cell line Caco-2 without affecting gamma-glutamyl transpeptidase activity. Kinetic studies revealed that orellanine acts on renal alkaline phosphatase as a noncompetitive inhibitor, whereas the intestinal and placental isoforms are inhibited competitively.

2,2'-Dipyridyl↗
PubMed1989

Relative efficacy of, and some adverse reactions to, different antihypertensive regimens.

Although it is a common belief that all antihypertensive agents are equally effective in reducing blood pressure, there is some evidence to the contrary, both in the general population and when specific patient demographics are considered. In black patients, beta blockers and angiotensin-converting enzyme (ACE) inhibitors have been shown to be less effective at reducing blood pressure than the thiazide diuretics. After age 60, the percentage of responders to beta blockers is less than with calcium antagonists, and a higher percentage of elderly patients also achieve normotensive blood pressure levels with diuretic therapy than with beta blockers. When a thiazide diuretic is added to an ACE inhibitor, beta blocker or calcium antagonist, the number of normotensive responders increases significantly. Combinations of some other agents (i.e., an ACE inhibitor plus a beta blocker) may not, however, improve efficacy. Diuretics, beta blockers and ACE inhibitors are all generally well tolerated, with a 9 to 10% incidence of subjective side effects. The use of calcium antagonists and especially the centrally acting adrenergic inhibitors may result in more frequent adverse effects. Data from long-term, diuretic-based clinical trials do not support the statement that diuretic therapy results in sustained elevations in lipid levels. These trials have shown cholesterol levels to be at or below baseline after long-term diuretic therapy. The use of beta blockers, on the other hand, may result in long-term elevation of triglyceride levels and a slight decrease in high-density lipoprotein cholesterol. Calcium antagonists and ACE inhibitors do not affect lipid levels, and alpha blockers may actually lower cholesterol levels and increase high-density lipoprotein levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1989

The costs of treating hypertension.

Recent surveys in the U.S. have reported, for the first time, that a significant number of patients with hypertension are finding that the cost of medication and treatment in general is an obstacle to treatment. The cost of management of hypertension can be contained if: a) the diagnostic workup is kept simple (this does not include the use of routine echocardiography or 24-hour monitoring) and b) medications that are relatively inexpensive and easily titratable on one or two visits are chosen. Despite some claims to the contrary, there are relatively few instances where significant metabolic changes are noted, regardless of the medication chosen, that require repeated blood determinations or frequent office visits.

Humans↗
PubMed1989

Chain configuration and flexibility gradient in phospholipid membranes. Comparison between spin-label electron spin resonance and deuteron nuclear magnetic resonance, and identification of new conformations.

The electron spin resonance spectra of 1-myristoyl-2-[n-(4,4-dimethyloxazolidine-N-oxyl)myristoyl]-sn- glycero-3-phosphocholine spin-label positional isomers (n = 6, 10, and 13) have been studied in oriented, fully hydrated bilayers of dimyristoylphosphatidylcholine, as a function of temperature and magnetic field orientation. The spectra have been simulated using a line-shape model which incorporates chain rotational isomerism, as well as restricted anisotropic motion of the lipid molecules as a whole, and which is valid in all motional regimes of conventional spin-label electron spin resonance (ESR) spectroscopy. At least one component of the lipid motion is found to lie in the slow-motion regime for all label positions, even in the fluid liquid crystalline phase, well above the phase transition. In the gel phase, the chain isomerism lies in the slow-motional regime, and the overall motions are at the rigid-limit. In the fluid phase, the chain isomerism is in the fast-motional regime, and the chain axis motions are in the slow regime. This indicates that the commonly used motional-narrowing theory is not appropriate for the interpretation of spin-label spectra in biological membranes. The simulation parameters yield a consistent description for the chain order and dynamics for all label positions. The correlation times and order parameters for the overall motion are the same at all positions down the chain, whereas the chain conformation and trans-gauche isomerism rate display a characteristic flexibility gradient, with increasing motion towards the terminal methyl end of the chain. Significantly, it is found that all six distinct tetrahedral orientations of the hyperfine tensor at the labeled segment are required for a consistent description of the chain isomerism. For the C-6 segment only the 0 degree (trans) and two 60 degrees (gauche) orientations are significantly populated, for the C-10 position two further 60 degrees orientations are populated, and for the C-13 position all orientations have non-vanishing populations. Detailed comparisons have been made with the results of 2H nuclear magnetic resonance (NMR) measurements on dimyristoylphosphatidylcholine labeled at the same position in the sn-2 chain, and using an identical motional model. The parameters of overall reorientation, both order parameter and correlation times, have very similar values as determined by ESR and NMR. The major difference between the results from the two methods lies in the conformational populations at the labeled chain segment and the trans-gauche isomerization rate in the gel phase. The conformational order is much lower for the spin-labeled chain segments than for the corresponding deuterium-labeled segments, and the isomer interconversion rates in the gel phase(although displaying a mobility gradient in both cases) are found to be much slower in the former case. In addition the spin-label measurements provide information on the macro order (chain tilt), which is only available from oriented samples. These results are consistent between the different spin label positions and are in agreement with the findings from x-ray diffraction.

Dimyristoylphosphatidylcholine↗
PubMed1989

Lipid abnormalities and diuretics.

Diuretic-based treatment regimens for hypertension have consistently reduced blood pressure and the morbidity and mortality due to stroke and overall cardiovascular disease. Studies have been less consistent in showing a beneficial effect on morbidity and mortality from coronary heart disease. However, speculations that possible adverse effects of diuretics on lipids may have contributed to the lack of a consistent beneficial effect on coronary heart disease are not substantiated by long-term clinical trials.

Benzothiadiazines↗
PubMed1989

Results of treatment of the elderly hypertensive.

Data from several long-term clinical trials, including the European Working Party on Hypertension in the Elderly, indicate that lowering blood pressure in patients 60 years of age and older is beneficial when those patients have diastolic/systolic hypertension. Overall cardiovascular complications are reduced, and the incidence of congestive heart failure and cerebrovascular complications is decreased. Diuretics--with or without a potassium-sparing component--were used as initial therapy in these major clinical trials. The results of these studies provide a basis for treating elderly hypertensive patients over the age of 60.

Age Factors↗
PubMed1989

Physiologic changes in the elderly: are they clinically important in the management of hypertension?

Age-related conditions and physiologic changes must be considered when managing the treatment of elderly hypertensives. Decreased aortic distensibility, structural changes in peripheral arteries and arterioles, reduced cardiac output and stroke volume, changes in baroreceptor sensitivity, and decreased lean body mass are factors that can influence the outcome of therapy in this patient population. Nevertheless, results from recent, well-controlled studies indicate that elderly individuals can be treated successfully and safely with antihypertensive drugs, providing care is taken in choosing an appropriate agent and adjusting dosage in light of these age-related factors.

Aged↗
PubMed1989

Regional differences in death rates among postneonatal infants in Kentucky, 1982-1985.

Our objective was to analyze differences in postneonatal mortality rates between the southeastern (Appalachian) region of Kentucky and the remainder of the state to identify factors associated with increased mortality in the Appalachian (AP) region. The relative risk of postneonatal deaths in the AP region when compared with the remainder of Kentucky (KY) was 1.38 (95% confidence interval = 1.15-1.65). Adjustment for birth weight, maternal age, and marital status of the parents had no appreciable effect on the risk ratio; however, adjustment for maternal education negated the increased risk of postneonatal death among the AP region births. When causes of postneonatal death were compared, three specific disease groupings were disproportionately represented among AP infants: Sudden Infant Death Syndrome (SIDS); congenital malformations; and infections. Most striking was the excess risk of infection-related death because it represents a preventable component in the postneonatal mortality excess of the AP region; and, because of the apparent association with maternal "under education." These findings are discussed within a public health intervention context.

Appalachian Region↗
PubMed1988

Role of L3T4+ and Lyt-2+ donor cells in graft-versus-host immune deficiency induced across a class I, class II, or whole H-2 difference.

The i.v. injection of parental T cells into F1 hybrid mice can result in a graft-vs-host (GVH)-induced immune deficiency that is Ag nonspecific and of long duration. The effect of the GVH reaction (GVHR) on the host's immune system depends on the class of F1 MHC Ag recognized by the donor cells. To determine the role of different subsets of donor-derived T cells in the induction of GVHR, donor spleen cells were negatively selected by anti-T cell mAb and C, and the cells were injected into F1 mice that differed from the donor by both class I and II MHC Ag or by class I or class II MHC only. The induction of GVHR across class I + II differences was found to require both L3T4+ and Lyt-2+ parental cells. Induction of GVHR across a class II difference required only L3T4+ parental T cells in the combination tested [B6-into-(B6 x bm12)F1]. In contrast, B6 Lyt-2+ cells were sufficient to induce GVHR across a class I difference in (B6 x bm1)F1 recipients. In addition, a direct correlation was observed between the cell types required for GVH induction and the parental T cell phenotypes detected in the spleens of the GVH mice. The number of parental cells detected in the unirradiated F1 hosts was dependent upon the H-2 differences involved in the GVHR. Induction of a class I + class II GVHR resulted in abrogation of both TNP-self and allogeneic CTL responses. In contrast, induction of a class II GVHR resulted in only a selective loss of TNP-self but not of allogeneic CTL function. Unexpectedly, the induction of a class I GVHR also resulted in the selective loss of the TNP-self CTL response. Thus, these class I and class II examples of GVH both result in the selective abrogation of L3T4+ Th cell function. The data are discussed in terms of respective roles of killer cells and/or suppressor cells in the induction of host immune deficiency by a GVHR, and of the selective deficiency in host Th cell function induced by different classes of GVHR.

Animals↗
PubMed1988

Stimulation of receptor-mediated low density lipoprotein endocytosis in neuraminidase-treated cultured bovine aortic endothelial cells.

Sialic acids, occupying a terminal position in cell surface glycoconjugates, are major contributors to the net negative charge of the vascular endothelial cell surface. As integral membrane glycoproteins, LDL receptors also bear terminal sialic acid residues. Pretreatment of near-confluent, cultured bovine aortic endothelial cells (BAEC) with neuraminidase (50 mU/ml, 30 min, 37 degrees C) stimulated a significant increase in receptor-mediated 125I-LDL internalization and degradation relative to PBS-treated control cells. Binding studies at 4 degrees C revealed an increased affinity of LDL receptor sites on neuraminidase-treated cells compared to control BAEC (6.9 vs. 16.2 nM/10(6) BAEC) without a change in receptor site number. This enhanced LDL endocytosis in neuraminidase-treated cells was dependent upon the enzymatic activity of the neuraminidase and the removal of sialic acid from the cell surface. Furthermore, enhanced endocytosis due to enzymatic alteration of the 125I-LDL molecules was excluded. In contrast to BAEC, neuraminidase pretreatment of LDL receptor-upregulated cultured normal human fibroblasts resulted in an inhibition of 125I-LDL binding, internalization, and degradation. Specifically, a significant inhibition in 125I-LDL internalization was observed at 1 hr after neuraminidase treatment, which was associated with a decrease in the number of cell surface LDL receptor sites. Like BAEC, neuraminidase pretreatment of human umbilical vein endothelial cells resulted in enhanced receptor-mediated 125I-LDL endocytosis. These results indicate that sialic acid associated with either adjacent endothelial cell surface molecules or the endothelial LDL receptor itself may modulate LDL receptor-mediated endocytosis and suggest that this regulatory mechanism may be of particular importance to endothelial cells.

Animals↗