Biomedical subjects

A Maier

Publications and source records attributed to A Maier.

At least 109 records · Page 6Linked to original sources

PubMed1993

Development of chicken intrafusal muscle fibers.

The first sign of developing intrafusal fibers in chicken leg muscles appeared on embryonic day (E) 13 when sensory axons contacted undifferentiated myotubes. In sections incubated with monoclonal antibodies against myosin heavy chains (MHC) diverse immunostaining was observed within the developing intrafusal fiber bundle. Large primary intrafusal myotubes immunostained moderately to strongly for embryonic and neonatal MHC, but they were unreactive or reacted only weakly with antibodies against slow MHC. Smaller, secondary intrafusal myotubes reacted only weakly to moderately for embryonic and neonatal MHC, but 1-2 days after their formation they reacted strongly for slow and slow-tonic MHC. In contrast to mammals, slow-tonic MHC was also observed in extrafusal fibers. Intrafusal fibers derived from primary myotubes acquired fast MHC and retained at least a moderate level of embryonic MHC. On the other hand, intrafusal fibers developing from secondary myotubes lost the embryonic and neonatal isoforms prior to hatching and became slow. Based on relative amounts of embryonic, neonatal and slow MHC future fast and slow intrafusal fibers could be first identified at E14. At the polar regions of intrafusal fibers positions of nerve endings and acetylcholinesterase activity were seen to match as early as E16. Approximately equal numbers of slow and fast intrafusal fibers formed prenatally; however, in postnatal muscle spindles fast fibers were usually in the majority, suggesting that some fibers transformed from slow to fast.

Animals↗

PubMed1993

In vitro and in vivo testing of the dopamine D1 ligand [123I]SCH 23982 with respect to its potential application in SPET investigations.

[123I]SCH 23982, a dopamine D1 ligand, was labelled in a large scale process and then tested in vitro for binding to rat brain sections and membranes. Because of the promising values of KD = 1.5 x 10(-10) M and Bmax = 0.7 x 10(-11) mol/g, in vivo evaluation was performed on rats and normal volunteers to test its possible usefulness for SPET imaging. In competition experiments, a higher binding in the presence of sulpiride was found while ketanserin displaced [123I]SCH 23982 only at a 10,000-fold excess. Differences between rats and men were seen with respect to their metabolism. SPET investigations failed because the washout of [123I]SCH 23982 was too rapid.

Aged↗

PubMed1993

Color flow Doppler sonography for extracorporeal shock wave lithotripsy.

This report documents the usefulness of color Doppler sonography for early verification of urinary stone fragmentation during extracorporeal shock wave lithotripsy with ultrasonographic focusing. In the experimental study lithotripsy was performed on human urinary stones placed in pig kidneys. Increasing color flow within the stone mass created by movement of small fragments indicated fragmentation earlier than pixel movement on the standard gray scale sonogram. The success of treatment was demonstrated macroscopically. In the clinical study 25 patients with radiopaque kidney stones were treated by color Doppler guided shock wave lithotripsy and compared to a control group of 32 patients with similar stone characteristics in whom the end point of treatment was chosen based on B-mode sonography alone. The amount of color flow within the stone reflex determined the end point of treatment. The degree of fragmentation was confirmed by fluoroscopy immediately after treatment. Disintegration was successful in all cases and fragments passed spontaneously. Color Doppler imaging during shock wave lithotripsy provides reliable information on the spatial and temporal characteristics of stone fragmentation, and is superior to B-mode sonography by providing more immediate, objective information on stone fragmentation and allowing better evaluation of the focal zone. With the help of this technique, the number of applied shock waves could be reduced by 20% compared with the control group.

Animals↗

PubMed1992

The avian muscle spindle.

The literature on the morphology and physiology of the avian muscle spindle is reviewed, with emphasis placed on the period from 1960 to 1991. Traits similar to or different from mammalian spindles are recognized. Apart from receptors with low intrafusal fiber counts, bird spindles contain two or three types of intrafusal fiber. Unlike that of mammals, the equatorial fiber structure in birds does not lend itself to classification into nuclear bag and nuclear chain types. Avian intrafusal fibers are separable into types based on differences in myosin heavy chain composition and motor innervation, but apportionment of these fiber types to individual spindles is more variable in birds than in mammals. There is morphological evidence in birds for the existence of both gamma and beta innervation; however, confirmation of these systems by physiological experiments is at best sketchy. A general lack of physiological data is currently the greatest drawback to a better understanding of how the avian receptor works, and what role it plays in sensorimotor integration.

Animals↗

PubMed1992

Myosin heavy chain composition of single fibres and their origins and distribution in developing fascicles of sheep tibialis cranialis muscles.

The myosin heavy chain (MHC) composition of single muscle fibres in developing sheep tibialis cranialis muscles was examined immunohistochemically with monoclonal antibodies to MHC isozymes. Data were collected with conventional microscopy and computerized image analysis from embryonic day (E) 76 to postnatal day (PN) 20, and from adult animals. At E76, 23% of the young myofibres stained for slow-twitch MHC. The number of these fibres considerably exceeded the number of primary and secondary myotubes. By E100, smaller fibres, negative for slow-twitch MHC, encircled each fibre from the initial population to form rosettes. A second population of small fibres appeared in the unoccupied spaces between rosettes. Small fibres, whether belonging to rosettes or not, did not initially express slow-twitch MHC, expressing mainly neonatal myosin instead. These small fibres then diverged into three separate groups. In the first group most fibres transiently expressed adult fast myosin (maximal at E110-E120), but in the adult expressed slow myosin. This transformation to the slow MHC phenotype commenced at E110, was nearing completion by 20 postnatal days, and was responsible for approximately 60% of the adult slow twitch fibre population. In the other two groups expression of adult fast MHC was maintained, and in the adult they accounted for 14% (IIa MHC) and 17% (IIb MHC) of the total fibre numbers. We conclude that muscle fibre formation in this large muscle involves at least three generations of myotube. Secondary myotubes are generated on a framework of primary myotubes and both populations differentiate into the young myofibres which we observed at E76 to form rosettes. Tertiary myotubes, in turn, appear in the spaces between rosettes and along the borders of fascicles, using the outer fibres of rosettes as scaffolds.

Animals↗

PubMed1992

Sensory and motor innervation of bird intrafusal muscle fibers.

1. Most bird muscle spindles are supplied by only one primary afferent. 2. Secondary afferents occur irregularly. 3. Sensory terminals are covered by a basal lamina and a collagenous sheath. 4. Two types of motor terminal are recognized which can be referred to specific types of intrafusal fiber. 5. The sensory and motor innervation of bird intrafusal fibers is less understood than that of mammalian intrafusal fibers.

Afferent Pathways↗

PubMed1992

[Saphenous vein bypass stenoses, early diagnosis with color coded Doppler sonography].

In a prospective study 54 patients with 62 saphenous vein arterial bypass grafts were examined by colour-coded Doppler sonography and angiography. Five cases of graft occlusion were diagnosed by colour-coded Doppler sonography and confirmed by angiography. In comparison with angiography, colour-coded Doppler sonography showed a sensitivity of 92% and a specificity of 100% in the detection of focal graft stenosis. Only two stenoses in the region of the distal anastomosis could not be detected by colour-coded Doppler sonography. In 28 cases a marked dilatation of the proximal anastomosis was found corresponding to the surgically used patch angioplasty. Within this dilated bypass segment, turbulence and flow reversal zones were demonstrated, which might be predisposing factors for graft stenosis. Colour-coded Doppler sonography can accurately detect saphenous vein arterial bypass graft stenoses and should be routinely used in postoperative screening.

Adult↗

PubMed1992

Circadian rhythm and pulsatility of parathyroid hormone secretion in man.

OBJECTIVE: We wished to investigate the circadian rhythm and pulsatility of parathyroid hormone (PTH) secretion in man, as conflicting results have been published. DESIGN AND PATIENTS: To investigate the circadian rhythm during daytime, we sampled (a) peripheral blood at hourly intervals in 12 healthy young men from 0900 h until 1700 h. For observation of pulsatility, we sampled (b) peripheral blood at 1-minute intervals for 1 hour in three healthy men and three healthy women (mean 27.7 years, range 21-56 years) and (c) at 1-minute intervals for 30 minutes in 21 patients with surgically confirmed primary hyperparathyroidism (pHPT). MEASUREMENTS: The serum levels of intact PTH were measured by two-site immunoradiometric assay and special care was taken to reduce intra-assay variability, especially at the normal PTH concentration. In series (a), ionized calcium, total calcium and phosphate were also determined. RESULTS: A circadian rhythm during daytime was found for intact PTH in healthy men and women with a nadir at 0930 h and a peak in the afternoon. Ionized calcium and total calcium (protein-adjusted) decreased and phosphate increased in the afternoon. These changes were all statistically significant (P < 0.02). Pulsatility of PTH: Statistical cluster analysis of the data showed no pulsatility either in healthy persons or in patients with primary hyperparathyroidism. In two healthy women and one healthy man slight changes of longer duration were discovered, but no complete pulses. In five patients with primary hyperparathyroidism, larger differences between the highest and lowest concentrations of intact PTH were found, but no complete pulses. CONCLUSIONS: Our data show a significant circadian rhythm during daytime of intact PTH and only minor changes from minute to minute. The alterations in PTH-levels occurred at longer time intervals in healthy persons. In some patients with primary hyperparathyroidism, decreases of PTH-levels were found. The circadian rhythm of PTH may be due to slight changes in calcium or phosphate concentration.

Adult↗

PubMed1992

A viscometric method of measuring plasma fibrinogen concentrations.

A technique based on deducing the viscosity of serum from that of plasma was compared with the commonly used Clauss method. The two methods correlated closely (r = 0.914). The reproducibility of the viscometric method was slightly poorer than the Clauss technique at low fibrinogen concentrations, equal to that at medium fibrinogen concentrations, and marginally better at high concentrations. Fibrinogen can therefore be measured reasonably accurately with the viscometric method, and can be recommended as an alternative for laboratories possessing a viscometer.

Adult↗

PubMed1992

Calcium regulating hormones after oral and intravenous calcium administration.

The aim of this study was to determine the changes in serum calcium concentration and in the concentrations of calcium regulating hormones after a single oral or intravenous calcium administration. Standard dosages of calcium, as used in routine patient care, were employed. Intact parathyrin, calcitonin, calcitriol, calcidiol, total calcium, ionized calcium, total protein and phosphate were determined in 12 healthy young men before and up to 8 h after oral and intravenous administration of calcium. During a fortnight there were four study days with 1000 mg calcium orally (p.o.), 2000 mg orally, 180 mg calcium intravenous (i.v.) and a control day without calcium. During the study the men were on a low calcium diet. We observed a sharp increase in the calcium concentration after i.v. administration (15 min: total Ca: + 0.48 +/- 0.32 mmol/l; ionized Ca: + 0.25 +/- 0.15 mmol/l; p < 0.01). The concentration increase after the two oral loads was nearly identical. The maximal concentration of total calcium was reached after 120 min (1000 mg: + 0.1 +/- 0.04 mmol/l; p < 0.001; 2000 mg: + 0.12 +/- 0.04 mmol/l; p < 0.001). There was a significant increase in urinary calcium after all modes of calcium administration. Calcitonin increased significantly only after i.v. injection of calcium (+ 9.2 +/- 3.4 pmol/l; p < 0.001) while parathyrin decreased significantly after all modes of calcium administration (i.v.: 15 min: -1.9 +/- 0.88 pmol/l; p < 0.01; 1000 mg: 90 min: -0.78 +/- 0.75 pmol/l; p < 0.001; 2000 mg: 90 min: -1.02 +/- 0.57 pmol/l; p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗

PubMed1992

Fast and slow intrafusal fibre type systems in chicken leg muscle spindles.

The results of this study indicate that in serial sections incubated with monoclonal antibodies against MHC and stained for mATPase, intrafusal fibres in chicken leg muscle spindles are separable into slow and fast types. As observed here, fast fibres are a homogeneous group; however, it had been shown earlier (Maier & Zak, 1990) that based on relative amounts of slow MHC, the slow fibres can be further divided into 2 subgroups. These 3 types of intrafusal fibre conform to 3 recently demonstrated patterns of motor innervation (Maier, 1991). It is suggested that the respective actions of slow and fast intrafusal fibres produce different components of the afferent discharge of chicken muscle spindles.

Animals↗

PubMed1992

Immunoluminometric assay of chromogranin A in serum with commercially available reagents.

Chromogranin A (Cg A) is a useful marker of neuroendocrine neoplasia in humans. Here we describe an immunoluminometric assay (ILMA) for measuring Cg A in serum, with use of a new tube as a solid phase. The new tube has a large surface area and is coated with a polyclonal antibody. Optimized coating conditions provide a high IgG adsorption to the polystyrene wall. Serum is added to the coated tube and incubated for 2 h or overnight. After washing the tubes, acridinium ester-labeled monoclonal antibody against Cg A is added and incubation is continued for 2 h. The tubes are washed again and the bound luminescence is measured. The assay is very sensitive (detection limit 1 microgram/L, if 25 microL of serum is used), is specific for human Cg A, and offers a wide dynamic range (1-1000 micrograms/L). The range in healthy humans is 10-53 micrograms/L (median 30 micrograms/L). The correlation of serum Cg A to creatinine and parathyroid hormone is described. We also report the influence of intravenous calcium injection on Cg A concentrations in serum.

Antibodies, Monoclonal↗

PubMed1991

The effects of cyclosporin A on eicosanoid excretion in patients with rheumatoid arthritis.

Alterations in renal eicosanoid levels have been postulated as a factor in cyclosporin A (CSA) nephrotoxicity. The effects of CSA on renal eicosanoid excretion in rheumatoid arthritis were studied over a 24-week period, during which treatment with nonsteroidal antiinflammatory drugs was discontinued. The initial dosage of CSA was 4 mg/kg/day; at week 24, the mean dosage of CSA was 3.9 mg/kg/day. At week 24, the mean (+/- SD) serum creatinine level (1.04 +/- 0.24 mg/dl) was 32% above the baseline value; renal blood flow had decreased by 21% (P less than 0.03) and the glomerular filtration rate had decreased by 16%. There was a significant increase (P less than 0.03) in the 2,3-dinor thromboxane B2 level at week 2, but there was no significant change in the levels of the other eicosanoids. This study demonstrates that after CSA treatment, there is a selective increase in a thromboxane metabolite that parallels an increase in renal vascular resistance, even in the absence of nonsteroidal antiinflammatory drugs, and with unimpaired formation of other vasodilator eicosanoids.

Adult↗

PubMed1991

Axon contacts and acetylcholinesterase activity on chicken intrafusal muscle fiber types identified by their myosin heavy chain composition.

Muscle spindles of 8-week old chicken tibialis anterior muscles were examined to determine if specific intrafusal fiber types were also characterized by differences in motor innervation. Incubation with a monoclonal antibody against myosin heavy chains permitted the identification of strongly reactive, moderately reactive and unreactive intrafusal fibers. The innervation of each fiber type was evaluated in silver-impregnated sections, and in sections incubated with a monoclonal antibody against acetylcholinesterase. There was no acetylcholinesterase activity at the midequator of any fiber. At the juxtaequator and at the pole strongly reactive fibers typically exhibited fewer axon contacts and less acetylcholinesterase activity than unreactive and moderately reactive fibers. Differences were also recognized at neuromuscular junctions in the size and shape of acetylcholinesterase-positive sites. At the juxtaequator and at the pole strongly reactive fibers and moderately reactive fibers displayed significantly more small, dot-like acetylcholinesterase sites than unreactive fibers. On the contrary, the greatest number of larger, stout sites was found on unreactive fibers and the least number on strongly reactive fibers. Moderately reactive fibers took an intermediate position. The results indicate that myosin heavy chain-based chicken intrafusal fiber types are also set apart by differences in innervation.

Acetylcholinesterase↗

PubMed1990

Presence in chicken tibialis anterior and extensor digitorum longus muscle spindles of reactive and unreactive intrafusal fibers after incubation with monoclonal antibodies against myosin heavy chains.

Cross and longitudinal sections from the encapsulated portions of chicken tibialis anterior and extensor digitorum longus muscle spindles were examined to determine whether their intrafusal fibers were a structurally homogeneous or heterogeneous population. The techniques used were the histochemical actomyosin (mATPase) reaction, and fluorescence immunohistochemistry employing two monoclonal antibodies, CA-83 and CCM-52, that are specific for myosin heavy chains. After incubation with antibody CCM-52, intrafusal fibers fluoresced either strongly or weakly to moderately. Antibody CA-83 was even more selective. In addition to identifying the strongly reactive category, it clearly separated the remaining fibers into unreactive and moderately reactive groups. As a whole, after incubation for mATPase, pH 9.6 preincubation, unreactive fibers stained darker than strongly reactive fibers. Moreover, the cross-sectional area of the unreactive fibers was significantly larger than that of the strongly reactive fibers. In the average-size muscle spindle with six intrafusal fibers, there were four unreactive fibers and two strongly reactive fibers. In about one-third of the receptors examined, one moderately reactive fiber was present. Taken together, the data indicate that intrafusal fibers of chicken tibialis anterior and extensor digitorum longus muscles are not structurally homogeneous. The observed variations can be better explained in terms of different fiber types than of continuous gradients within one type of fiber.

Adenosine Triphosphatases↗

PubMed1990

Connective-tissue macromolecules in Golgi chicken tendon organs and at their interface with muscle fibers and adjoining tendinous structures.

Tendon organs from leg and forearm muscles of white leghorn chickens were examined with a library of monoclonal antibodies to determine the composition of their connective-tissue framework and the types of connective-tissue macromolecules that occur at the sites where muscle fibers attach to the receptors. The capsules of the tendon organs were positive for connective-tissue macromolecules typical of basal lamina (collagen type IV, laminin, and heparin sulfate proteoglycan) and for tenascin, collagen types III and VI, and fibronectin. Connective-tissue bundles in the lumen of a receptor reacted primarily with antibodies against collagen type I and 4-chondroitin sulfate. The narrow partitions that divide each lumen into compartments stained for collagen type III. Toward its tendinous end, a receptor made few contacts with muscle fibers. Instead, the capsule and the collagenous bundles blended gradually with the intermuscular portions of tendons. At the muscular end, the connections were more complex. Muscle fibers that attached in series to tendon organs split to produce basal lamina-covered, finger-like extensions, which were separated from each other by fissures. Tongues of connective tissue containing tenascin, collagen types I and VI, and fibronectin extended into the fissures. Distally the tongues were continuous with the tenascin in the capsule and just internal to the capsule, fibronectin and basal lamina macromolecules in the capsule, and collagen type I in the collagenous bundles. The uninterrupted presence of these macromolecules around terminating muscle fibers and in the capsule and/or the intraluminal collagen bundles suggests that muscle fibers that attach in series at the muscular end exert a force during muscular contraction on the intraluminal collagen bundles and on the receptor capsule.

Animals↗

PubMed1990

Arrangement of cytoskeletal filaments at the equator of chicken intrafusal muscle fibers.

The organization of the cytoskeleton at the equator of chicken intrafusal fibers was examined with immunofluorescence light microscopy, using monoclonal antibodies against myosin heavy chains, desmin, actin and tropomyosin. Actin was localized in the cytosol and in equatorial nuclei, while myosin heavy chains, desmin and tropomyosin were only observed in the cytosol. Although all four proteins were present at the equator and at the pole, the fluorescence produced after incubation with the different antibodies varied considerably between the two regions. Staining at the pole was in the form of striations, but at the equator it was non-striated and more uniform. The observed fluorescent patterns suggest that at the equator filaments are assembled into looser arrays than in the sarcomeres of the pole. A flexible cytoskeleton at the equator would be an appropriate substrate for distorting the affixed sensory endings during an applied stress.

Actins↗

PubMed1990

[Malignant mesothelioma of the pleura. Analysis of its immunohistochemical aspects].

To evaluate the usefulness of immunohistochemistry in the diagnostic distinction between pleural mesothelioma and metastatic adenocarcinoma to the pleura, the authors studied formalin-fixed paraffin-embedded tissue sections from 14 pleural mesotheliomas and 20 primary adenocarcinomas of the lung, stomach, ovary and breast by using 16 commercially available antibodies to cytokeratin (KL1), vimentin, EMA, CEA, CA19.9, CA125, Egp 34 (detected by HEA 125), secretory component, S100 protein, SP1-béta 1, Leu M1, alpha-1-AT, alpha-1-ACT, lysozyme, desmin and factor VIII. Keratin positivity was found in all mesotheliomas and adenocarcinomas. A coexpression of keratin and vimentin was present in 8/14 (57%) mesotheliomas but only in 2/20 (10%) adenocarcinomas. CEA and CA 19.9 were detected in 80% and 65% of the adenocarcinomas respectively, but not in any of the mesotheliomas. Interestingly, two adenocarcinomas (of the ovary and the stomach) that failed to stain for CEA, were immunoreactive to anti-CA 19.9 antibody. Thus, the combined use of anti-CEA and anti-CA 19.9 antibodies results in staining 90% of the adenocarcinomas. S100 protein, SP1-beta and Leu M1 were also absent in mesotheliomas but present only in less than half of the adenocarcinomas. Adenocarcinomas and mesotheliomas did not significantly vary in reaction to the remaining above mentioned antibodies. The authors conclude that the coexpression of keratin and vimentin and the absence of CEA and CA 19.9 might be the best criteria in the distinction of mesothelioma from metastatic non mucosecreting adenocarcinoma.

Adenocarcinoma↗