Biomedical subjects

I Mayer

Publications and source records attributed to I Mayer.

At least 37 records · Page 2Linked to original sources

PubMed2000

High-resolution electron microscopy study of synthetic carbonate and aluminum containing apatites.

Aluminum (Al)-containing calcium-deficient carbonated hydroxyapatites were produced by a precipitation method from aqueous solution with carbonate (0-6.1%) and aluminum (0.1-0.5%) concentrations close to those found in biological materials. Two series of apatites were prepared: one at pH 7.0 and another at pH 9. 0. High-resolution electron microscopy has shown that many of them possess structural defects such as screw dislocations, grain boundaries, and central defects. Samples with high carbonate content and high water and high Al(3+) content had a high amount of structural defects. Accordingly, a sample (7Al1) with a relatively high carbonate content (6.1%) and a sample (7Al6) without carbonate but with a relatively high water (2.0 mol) and Al(3+) content (0. 39%) presented the highest amount of structural defects, 54% and 47%, respectively. A sample (7Al13) with a low level of crystalline water (1 mol) and low carbonate (2.5%) showed a small amount of defects. The presence of water associated with Al(3+) induced a high number of crystals having a central defect with a great similarity to the so-called water layer of octacalcium phosphate (OCP). Observed images of all these crystals have shown good correspondence with the computer-simulated image based on the crystal structure of hydroxyapatite, indicating that the addition of Al(3+) and carbonate does not perturb the apatitic structure.

Aluminum↗

PubMed2000

Intermale competition in sexually mature arctic charr: effects on brain monoamines, endocrine stress responses, sex hormone levels, and behavior.

Sexually mature Arctic charr (Salvelinus alpinus) males were allowed to interact in pairs for 4 days in the absence of females. Agonistic behavior was quantified, and at the end of the experiment, plasma levels of glucose, cortisol, testosterone (T), 11-ketotestosterone (11-KT), and 17alpha,20beta-dihydroxy-4-pregnen-3-one (17alpha, 20beta-P) were determined alongside brain concentrations of serotonin (5-HT), 5-hydroxyindoleacetic acid (5-HIAA, the major 5-HT metabolite), dopamine (DA), and 3,4-dihydroxyphenylacetic acid (DOPAC, a major DA metabolite). Plasma cortisol and glucose were significantly elevated in subordinate fish, and the number of aggressive acts received showed positive correlations with plasma levels of glucose on day 1, during the development of the dominance relationship, and of cortisol on day 4, when the dominance relationship was established. In contrast, plasma concentrations of T and 11-KT were significantly higher in dominant than in subordinate males, and there was a similar tendency in plasma concentrations of 17alpha,20beta-P. Further, plasma levels of these gonadal steroids were correlated with the number of aggressive acts performed on day 4, but not with the number of aggressive acts received. The plasma cortisol concentrations did not correlate with either 5-HIAA:5-HT or DOPAC:DA ratios in any of the brain parts analyzed. Plasma glucose levels showed positive correlations with brain 5-HIAA:5-HT ratios. Negative correlations were observed between 5-HIAA:5-HT ratios in the optic tectum and between plasma levels of T, 11-KT, and 17alpha,20beta-P. Telencephalic DOPAC/DA ratios displayed a negative correlation with plasma levels of T, 11-KT, and 17alpha,20beta-P, but only in dominant males.

3,4-Dihydroxyphenylacetic Acid↗

PubMed2000

Evaluation of post-antibiotic effects of antipseudomonal antibiotics using an automated system.

Different methods have been described for determination of the post-antibiotic effects (PAEs) of antibiotics, from the conventional methods to the automatic measurement of bacterial regrowth. The PAEs of ciprofloxacin, ofloxacin and perfloxacin, as compared with those of amikacin, netilmicin and ceftazidime, have now been investigated for three clinical isolates of Pseudomonas species, using automated measurement of the growth with an Anthos microplate reader. It was found that, besides the well-known PAEs of aminoglycosides, quinolone antibiotics also exhibit drug- and concentration-dependent PAEs against clinical isolates of Pseudomonas when used in concentrations of 1/2x, 1 x or 5 x MIC. Of the three quinolones tested, pefloxacin showed the greatest PAE, independently of its MICs against the different strains. Ofloxacin had no or only an insignificant PAE, while ciprofloxacin had a marked PAE for all strains, including the reference strains.

4-Quinolones↗

PubMed2000

[Assessment of inflammatory activity in Crohn disease with hydro-MRI].

PURPOSE: To assess the value of hydro-MRI in the assessment of the activity of Crohn's disease. MATERIALS AND METHODS: After an oral bowel opacification using 1000 ml of a 2.5% mannitol solution, axial and coronal breath-hold sequences (T2W HASTE +/- FS, contrast-enhanced T1W FLASH FS) were acquired in 63 patients with Crohn's disease at 1.0 T. The enhancement of the bowel wall was correlated with other MRI findings, with the Crohn's disease activity index (CDAI), and the C-reactive protein (CRP). RESULTS: In Crohn's disease, contrast enhancement of the affected bowel wall is markedly increased in comparison with the normal bowel wall (+80 +/- 23% vs. +43 +/- 11%; p = 8 x 10(-11)). Positive correlations could be established between the increase of bowel wall enhancement and other MRI findings. Between the increase of bowel wall enhancement and the CDAI a poor correlation was found (r = 0.25; p = 0.046). There was no statistical correlation between the increase of bowel wall enhancement and the CRP (r = 0.09; p = 0.24). CONCLUSION: Hydro-MRI allows an assessment of the activity of Crohn's disease.

Adolescent↗

PubMed2000

Hydro-MRI in Crohn's disease: appraisal of disease activity.

RATIONALE AND OBJECTIVES: To appraise the value of hydro-MRI in the assessment of activity in Crohn's disease. METHODS: After bowel opacification with 1000 mL of an orally administered 2.5% mannitol solution was achieved, axial and coronal breath-hold sequences (T2-weighted half-Fourier acquisition single-shot turbo spin-echo sequences with or without fat saturation, dynamic T1-weighted fast low-angle shot sequences, and contrast-enhanced T1-weighted fast low-angle shot with fat saturation sequences) were acquired in 82 patients with proved Crohn's disease at 1.0 T. Enhancement of the bowel wall was correlated with other MRI findings, with the Crohn's disease activity index (CDAI), and with levels of C-reactive protein (CRP). RESULTS: In Crohn's disease, contrast enhancement of the affected bowel wall was markedly increased in comparison with the normal bowel wall (+80% +/- 22% versus +43% +/- 12%; P = 3 x 10(-15)). Positive correlations could be established between the increase in bowel wall enhancement and many other MRI findings. Between the increase in bowel wall enhancement and the CDAI, only a poor correlation was found (r = 0.25, P = 0.02). There was no statistical correlation between the increase in bowel wall enhancement and CRP. CONCLUSIONS: Hydro-MRI seems to be superior to the CDAI and CRP for the registration of Crohn's disease activity. In particular, differentiation between an active and an inactive (scarred) stenosis, which is crucial for the choice of therapeutic procedures, seems to be more reliable by the interpretation of several morphological and functional parameters on hydro-MRI than by the use of CDAI and CRP.

Adult↗

PubMed1999

Effects of testosterone on gonadotropins, testes, and plasma 17alpha,20beta-dihydroxy-4-pregnene-3-one levels in postbreeding mature Atlantic salmon, Salmo salar, male parr.

Atlantic salmon, Salmo salar, mature male parr were implanted with testosterone (T) in small (T3) or large (T10) Silastic capsules in the breeding season or at its end in November or December, in order to find out whether the postbreeding decline in 17alpha, 20beta-dihydroxy-4-pregnene-3-one (17,20beta-P) and milt production is a consequence of declining T levels. In the first of three experiments, fish were sampled the following January and March, whereas in the second and in the third they were sampled in April. Pituitary and plasma concentrations of gonadotropic hormone (GTHs) I and II and plasma levels of T, 11-ketotestosterone (11-KT) and 17, 20beta-P were measured by radioimmunoassays, and the testes were examined histologically. Administration of T prolonged the period in which running milt was present, suppressed Sertoli cells, and prevented the postbreeding decline in testes weight in experiment two. The postbreeding decline in plasma 17,20beta-P levels was diminished by T10 in experiment one, and by both T3 and T10 in experiment two. The similar decline in 11-KT levels was not influenced by T treatment (only studied in experiment one). T treatment also prevented a decline in pituitary GTH II content (in experiments two and three) and in plasma GTH II levels (only studied in experiment three). However, pituitary GTH I content was not influenced (experiment two and three), whereas plasma GTH I levels (only studied in experiment three) were suppressed by T. To summarize, T treatment prevents postbreeding decline in 17,20beta-P levels, probably via a stimulation of GTH II secretion. J. Exp. Zool. 284:425-436, 1999.

Animals↗

PubMed1999

Male-male competition and female choice in brown trout.

In some salmonid species, the females have been assumed to choose their mates on the size of the male's adipose fin. This hypothesis was tested in a stream water aquarium, in which 19 brown trout, Salmo trutta, females were allowed to choose between two males of the same body size but with different adipose fin sizes. The two males were separated from each other in cages. After the female had started to prepare her nest close to one of them, the males were released and allowed to fight each other for the opportunity to spawn. Out of 19 females, 14 prepared a nest closest to the male with the larger adipose fin. However, only six of the 14 females spawned with this male. Males that spawned were more dominant (i.e. were more likely to win fights). When the female spawned with the male she chose, he was less aggressive towards her than when she spawned with the other male. There were no significant differences in the plasma levels of testosterone (T) and 11-ketotestosterone (11-KT) between the chosen males and those not chosen. However, the dominant males had significantly higher plasma levels of T and 11-KT both before and after the experiment. The results support the view that female brown trout exhibit mate choice, but their choice is overruled by male-male competition. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗

PubMed1999

Feedback control of gonadotropins in Atlantic salmon, Salmo salar, male parr.II. Aromatase inhibitor and androgen effects.

Both positive and negative feedback on the (hypothalmus)- pituitary-gonad axis occur in salmonids. The aim of the present study was to investigate the role of different androgens, and in particular the involvement of aromatization of androgens to estrogens in feedback mechanisms. Previously mature Atlantic salmon, Salmo salar, male parr were studied in two experiments. In the first experiment, intact fish were implanted with Silastic capsules filled with the aromatase inhibitor 1,4,6-androstatriene-3,17-dione (ATD) in spring and sampled in the autumn when the rematuring males were starting to display running milt. In the second experiment, castrated males were implanted with capsules containing ATD, the androgens testosterone (T) and 11-ketoandrostenedione (11KA), or ATD and T combined in spring. These fish were sampled in the summer when rematuring fish were starting to show signs of gonadal growth. Pituitary and plasma gonadotropins (GTH I and GTH II) were studied using radioimmunoassay. In autumn, ATD treatment reduced pituitary and plasma GTH II levels. In summer, GTH II was consistently nondetectable in plasma. Castration diminished pituitary GTH II content. Treatment with T increased pituitary GTH II content, an effect that was attenuated when T treatment was combined with ATD. All these results are consistent with the presence of an aromatase-dependent positive feedback of T on GTH II. 11KA also had a stimulatory effect on GTH II, although weaker than that of T. Testicular size and spermiation was reduced by ATD in autumn; the latter of these results is likely to be due to the inhibitory effect of ATD on GTH II. Positive effects of ATD on plasma GTH I were found in autumn, indicative of an aromatase-dependent negative feedback in this phase. On the other hand, castration increased plasma and pituitary GTH I levels in summer, indicating that the gonads in this phase exert a predominantely negative control of GTH I. In summer, negative effects of T on GTH I pituitary levels were not suppressed, but were rather enhanced, by the combined treatment with ATD. Furthermore, plasma GTH I levels were lower after treatment with T in combination with ATD than with T or ATD separately. These negative effects of T were not diminished by ATD, so that they are nonaromatase-dependent. Furthermore, since they were actually more pronounced in the presence of ATD it is suggested that there is also a positive aromatase-dependent feedback component in this phase. In addition, 11KA had a negative effect on plasma and pituitary GTH I in castrated previously mature males. Thus, GTH I secretion is controlled by both aromatase-dependent and nonaromatase-dependent feedback effects, of which at least the former may be positive or negative depending on season. In summary, the feedback control of GTH I appears to be more complex than that of GTH II.

Androgens↗

PubMed1999

La ions in precipitated hydroxyapatites.

Hydroxyapatites were synthesized by precipitation from an aqueous solution with La3+ (0-0.75%) and with carbonate (0-6.1%) at controlled pH 7.0. Uptake of La3+ was 90-95% complete. Relatively low Ca/P (1.54-1.63) ratios were attributed to nonstoichiometry. Carbonate in samples was identified by IR spectroscopy as B-type carbonate. Lattice parameters of the hexagonal apatite structure were not affected by the La3+ content. Noncarbonated samples heated to 800 degrees C transform partially to beta-Ca3(PO4)2. Thermogravimetric analysis showed release of 0.4 mol adsorbed and 1 mol crystalline water up to 400 degrees C and decomposition of carbonate up to 900 degrees C in the samples. Luminescence data obtained for Gd-containing hydroxyapatites prove that Gd3+ ions are not incorporated in the precipitated hydroxyapatite. These findings suggest that, in the La-containing samples, La3+ is surface absorbed and not incorporated in hydroxyapatite.

Calcium↗

PubMed1999

Investigation of the synergic effects of aminoglycoside-fluoroquinolone and third-generation cephalosporin combinations against clinical isolates of Pseudomonas spp.

Antimicrobial synergy resulting from antibiotic combination therapy is often important in the treatment of serious bacterial infections. Previous studies have demonstrated synergy between an aminoglycoside and beta-lactam antibiotics in the treatment of Pseudomonas aeruginosa infections. The present paper investigates the synergic effects of aminoglycosides (amikacin and netilmicin) and fluoroquinolones (ciprofloxacin, ofloxacin and pefloxacin) in combination with third-generation cephalosporins (cefoperazone, ceftriaxone and ceftazidime) against 18 clinical isolates of Pseudomonas spp. The effects of these drugs were examined by three methods (disc diffusion, 'chequerboard' titration and the time-killing method), to evaluate the activities of the antibiotics alone and in combination against selected isolates. Fractional inhibitory concentration indices were calculated for all isolates with all combinations. Use of the disc diffusion method revealed that amikacin and netilmicin in combination with the three cephalosporins exhibited synergy against 7-12 isolates, whereas the combinations of quinolones and ceftazidime displayed synergic effects only in the case of 3-5 isolates. On 'chequerboard' titration, amikacin and ceftriaxone exerted synergy against seven of the isolates. The other combinations showed synergy against fewer isolates, but every combination demonstrated synergic effect against some of the isolates. The tested combinations had different effects against various Pseudomonas spp. With the time-killing method, the 1/2 x MIC of amikacin or ciprofloxacin in combination with the 1/2 x MIC of third-generation cephalosporins proved to be most effective. No antagonism was found with these combinations. Discrepancies in the detection of synergy were observed for the different methods.

Amikacin↗

PubMed1998

Effects of gonadectomy and steroids on plasma and pituitary levels of somatolactin in Atlantic salmon, Salmo salar.

Somatolactin (SL) is a hormone recently isolated and characterized from fish pituitaries. Although the functions of SL are still largely unknown, it has been implicated in reproduction. In this study, the effects of gonadal steroids on SL secretion were investigated in Atlantic salmon male parr in two experiments. In both, mature males were gonadectomized in the autumn and implanted with Silastic capsules containing testosterone (T), 11-ketoandrostenedione (11kA), or 17 alpha,20 beta-dihydroxy-4-pregnene-3-one (20-P), gonadectomized alone, or sham-operated. In addition, immature males were implanted with T or 11kA in experiment 1. After 4-5 weeks pituitaries and plasma were sampled and SL levels measured by radioimmunoassay (RIA). Plasma levels of T, 11-ketotestosterone, and 20-P were also measured by RIA. In experiment 1, initial immature males had lower (0.7 +/- 0.4 ng/ml) plasma SL levels than initial mature males (3.3 +/- 0.4 ng/ml), whereas pituitary content was not influenced. Gonadectomy significantly reduced both plasma SL levels (experiment 1, sham controls 5.6 +/- 0.5 ng/ml, castrated 1.6 +/- 0.5 ng/ml; experiment 2, sham controls 6.5 +/- 1.1 ng/ml, castrated 3.3 +/- 0.4 ng/ml) and the pituitary content of SL (experiment 1, sham controls 1206 +/- 187 ng/pituitary, castrated 663 +/- 104 ng/pituitary; experiment 2, sham controls 1043 +/- 199 ng/pituitary, castrated 629 +/- 70 ng/pituitary), suggesting that the testes stimulated the synthesis and release of pituitary SL. Overall, the effects of steroid replacement were inconsistent between the experiments, although in experiment 2 castrated males receiving the highest dose of T had significantly higher plasma SL levels (8.2 +/- 1.2 ng/ml) than all other castrated groups (1.8-4.3 ng/ml).

20-alpha-Dihydroprogesterone↗

PubMed1998

Effects of gonadectomy and androgen treatments on pituitary and plasma levels of gonadotropins in mature male Atlantic salmon, Salmo salar, parr--positive feedback control of both gonadotropins.

The aim of the present study was to clarify the role of feedback control on the (brain)-pituitary-gonadal axis in regulating FSH (gonadotropic hormone, GTH I) and LH (GTH II) in natural maturation in salmonids. In two experiments, 2-yr-old previously mature Atlantic salmon male parr were castrated or sham operated in the spring following their first reproductive season. In one of the experiments, castrated fish were also implanted with silicone elastomer capsules containing testosterone (T) or 11-ketoandrostenedione (11KA). The fish were sampled in July, September, and November (spawning period). Pituitary and plasma LH and FSH levels were measured using RIA and were lower in castrated than in sham-operated fish, indicating positive feedback on both FSH and LH. T, and to a lesser extent 11KA, increased pituitary LH content in castrated fish. The 11KA increased plasma and pituitary FSH levels, whereas T suppressed FSH in July and stimulated it in November. Plasma FSH levels peak earlier than LH, and it is suggested that if one or more feedback effects are involved in controlling the "all-or-nothing response," i.e., whether a fish will mature or not, a feedback effect on FSH is the most likely candidate.

Androstenes↗

PubMed1997

Videonasopharyngoscopy as an instrument for visual biofeedback during speech in cleft palate patients.

Videonasopharyngoscopy was used as an instrument for visual biofeedback during speech in cleft palate patients. Seventeen cleft palate patients were randomly selected for the study. All patients showed velopharyngeal insufficiency (VPI), compensatory articulation (CA) and negative movement of lateral pharyngeal walls (NMLPW) during speech. Nine patients received speech therapy for correcting CA. Eight patients received speech therapy and underwent videonasopharyngoscopy as an instrument for visual biofeedback of the velopharyngeal sphincter. After 12 weeks, NMLPW was modified in the patients receiving speech therapy and visual biofeedback. In contrast, NMLPW was still present in eight out of nine patients receiving only speech therapy. These patients received visual biofeedback and NMLPW was corrected in all cases. After six months, all 17 patients had corrected CA during isolated speech. All patients received a tailor-made pharyngeal flap. VPI was completely corrected in 15 cases. In the two cases in which VPI was still present postoperatively, the size of the defect at the velopharyngeal sphincter had been significantly reduced. In these two patients, visual biofeedback was used postoperatively for increasing lateral pharyngeal walls (LPW) motion towards the borders of the flap. After 18 months since the onset of speech therapy all the patients had normal nasal resonance and normal articulation during connected speech.

Biofeedback, Psychology↗

PubMed1997

Melatonin does not prevent long photoperiod stimulation of secondary sexual characters in the male three-spined stickleback Gasterosteus aculeatus.

Breeding in the three-spined stickleback is stimulated by long but not by short photoperiods in many seasons. The aim of the present study was to test the hypothesis that melatonin plays a role in the inhibitory effect of short photoperiod in this species. Adult nonbreeding males were kept either under constant light (Experiment 1) or under a stimulatory long photoperiod (16L 8D, Experiment 2), in water containing 0, 20, or 80 microg/liter melatonin for 16 hr/day for 28 days during the spring. These melatonin treatments were intended to simulate the daily melatonin pattern of a nonstimulatory short photoperiod. In the second experiment, fish were also kept under a nonstimulatory short photoperiod (8L 16D). In the natural breeding season the only germ cells found in the stickleback testes are spermatozoa and spermatogonia, a condition found in many fish under all treatments. In the first experiment, spermatogenesis was not influenced by melatonin. However, testes also containing spermatocytes and spermatids were more common in fish kept under 8L 16D and fish treated with 80 microg/liter melatonin than in 16L 8D controls in Experiment 2. Kidney hypertrophy, an androgen-dependent male secondary sexual characteristic in the stickleback, appeared in most males kept under constant light or 16L 8D and was not influenced by melatonin treatment. In contrast, control males kept under 8L 16D in Experiment 2 did not display kidney hypertrophy. Therefore, the presence of an extended period of elevated melatonin did not prevent the stimulatory effects of long photoperiod on development of this secondary sexual characteristic in the stickleback.

Animals↗

PubMed1997

Magnesium-containing carbonate apatites.

Hydroxyapatites precipitated at pH 7.0 and 9.0 with and without carbonate and with different amounts of magnesium were studied. Mg uptake, Ca/P ratios, and lattice constant data indicate that Mg is incorporated into the apatite lattice. IR spectra demonstrate the formation of B-type carbonate apatites with carbonate substituting for phosphate. Decomposition of carbonate-containing apatites at elevated temperatures up to 1000 degrees C is more gradual for apatites prepared at pH 9.0 than for those prepared at pH 7.0 for which an abrupt loss of carbonate occurs after 600 degrees C. Compounds synthesized without added carbonate partially transform to beta Ca3(PO4)2 (TCP) at about 700 degrees C. Greater transformation to TCP occurs as the Mg incorporation is increased, indicating the insertion of Mg into TCP and consequent stabilization of the TCP. SEM micrographs show increases in the size of crystallites when apatites are precipitated with Mg (in the 0.2-1.5% range), providing further evidence for Mg incorporation into the apatite structure.

Calcium↗

PubMed1996

Surgical correction of velopharyngeal insufficiency with and without compensatory articulation.

The final speech outcome in cleft palate patients depends on two elements: normalization of nasal resonance and correction of compensatory articulation (CA). The purpose of this paper is to demonstrate whether early surgical correction of velopharyngeal insufficiency (VPI) may decrease total time of speech therapy (ST) necessary to completely eliminate CA. A group of 29 cleft palate patients in which VPI and CA were demonstrated, were selected for the study group. Fourteen patients were randomly selected and underwent surgical correction of VPI as soon as placement of articulation during isolated speech was normal. The other 15 patients underwent speech therapy aimed to correct CA, these patients were followed until articulation was normal during connected speech. At this point in time they underwent surgical correction of VPI as the other 14 patients. Success rate for correcting VPI after the operation was not significantly different for both groups. Furthermore, total time of ST was not significantly different for both groups. It is concluded that normalization of nasal resonance before articulation is corrected during connected speech does not seem to reduce total time of ST necessary to completely correct CA in cleft palate patients.

Adolescent↗

PubMed1995

Effect of diltiazem on coronary flow reserve in patients with microvascular angina.

Microvascular angina is characterized by ischemia-like symptoms in patients with normal coronary arteries and reduced coronary flow reserve. Clinical observations suggested an improvement in clinical symptomatology and exercise tolerance after treatment with calcium antagonists. The effect of diltiazem on coronary flow reserve was evaluated in controls and in patients with microvascular angina. Coronary flow reserve was measured in 16 normotensive patients (7 females, 9 males, mean age 51 +/- 10 years) with angiographically normal coronary arteries. Coronary blood flow was determined at rest, after dipyridamole (0.5 mg/kg) and following intravenous administration of diltiazem (10 mg) using coronary sinus thermodilution technique. Coronary flow reserve was calculated as coronary blood flow after dipyridamole divided by coronary blood flow at rest. Patients with normal coronary flow reserve (coronary flow reserve > 2.0) received either dipyridamole alone (group 1, controls, n = 6) or dipyridamole and diltiazem (group 2, n = 5), whereas patients with reduced coronary flow reserve (coronary flow reserve < 2.0) obtained dipyridamole and diltiazem (group 3, n = 5). Resting coronary flow was identical in the three groups, but after maximal vasodilation with dipyridamole, coronary flow increased significantly more in groups 1 and 2 than in group 3 (P < 0.05, analysis of variance (ANOVA)). Coronary flow reserve was 2.5 in group 1 and 2.3 in group 2, but was significantly reduced in group 3 (1.3; P < 0.05, ANOVA). Intravenous diltiazem failed to increase coronary blood flow in groups 2 and 3. Therefore, diltiazem does not improve reduced coronary flow reserve in patients with microvascular angina, but leaves coronary flow reserve unaffected. The failure to ameliorate impaired coronary flow reserve with diltiazem is in contrast to the reported clinical improvement after calcium channel blockade in these patients. Thus, other factors such as structural abnormalities in the microcirculation or functional abnormality in smooth muscle relaxation not responsive to calcium channel blockade are probably responsible for the occurrence of myocardial ischemia in patients with microvascular angina.

Analysis of Variance↗

PubMed1994

[Prinzmetal's variant angina: a case report].

Prinzmetal's angina is a variant of the classic exertion dependent angina pectoris. Typical is the appearance of the symptoms at rest during early morning hours. It is due to spasms in the coronary arteries. Various provocation tests may be used to trigger spasms, among others hyperventilation which leads to vasoconstriction of coronary arteries. The case of a 53-year-old patient with Prinzmetal's angina is described in whom spasms of the right coronary artery could be evoked by hyperventilation. The following pathogenetic mechanisms may be possible in Prinzmetal's angina: disturbed endothelial permeability, endothelial dysfunction, or secretion of vasoconstrictive substances as well as local hypersensitivity of segments disturbed by atherosclerotic lesions to circulating vasoconstrictors.

Angina Pectoris, Variant↗