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Biomedical subjects

A Maier

Publications and source records attributed to A Maier.

At least 145 records · Page 8Linked to original sources
PubMed1985

Simultaneous determination of trace elements in lavage fluids from human bronchial alveoli by energy dispersive x-ray fluorescence. 1: Technique and determination of the normal reference interval.

We have applied energy dispersive x-ray fluorescence to the analysis of broncho-alveolar lavage fluids, to determine the concentration of several elements simultaneously with manipulation of the sample minimized. A 20-microL sample of a homogenized lavage fluid, to which two internal standards (containing Y and V) have been added, is deposited on a polypropylene film, 4 microns in thickness, and analyzed by x-ray fluorescence. We report the analytical procedure, the detection limits, and the reproducibility. The normal concentration range for trace elements is reported for a selected population. The simplicity and rapidity of the method, and the possibility of automating measurements, make this procedure suitable for screening large numbers of lavage specimens and to establish the diagnosis of some pneumoconioses.

Blood↗
PubMed1984

Effects of semisynthetic diets on xenobiotic metabolizing enzyme activity and morphology of small intestinal mucosa in humans.

We studied the effects of semisynthetic (elemental) diets on the function and morphology of the human small intestine. The enzymatic capacity of the intestinal mucosa to metabolize lipophilic xenobiotics was investigated using jejunal biopsy specimens from 15 normal subjects who were on an isocaloric, nutritionally balanced semisynthetic diet for 7 days and thereafter on a normal home diet. Each subject underwent biopsy twice: on day 7 of semisynthetic diet and again on home diet 2-6 wk later. The jejunal mucosal tissue was examined by histologic morphometry and stereomicroscopy. Moreover, 25-50 mg of the biopsy material was homogenized and the following enzyme activities were determined in 20,000 g supernatant: for cytochrome P450-dependent monooxygenase activity with 7-ethoxycoumarin O-deethylase (EOD) and with nicotinamide adenine dinucleotide phosphate (NADPH)-cytochrome c reductase and for conjugation activity with 1-naphthol glucuronyltransferase (NGT). The NGT and reductase activities were unchanged by the dietary alterations. However, the EOD activity was significantly depressed on semisynthetic diet and rose to control range on home diet (from 5.3 +/- 2.5 to 12.4 +/- 8.6 pmol/min X 10 mg wet wt). Male subjects had significantly higher EOD activities than female subjects on semisynthetic diet (6.6 +/- 2.3 vs. 3.2 +/- 0.9) as well as on home diet (16.3 +/- 9.0 vs. 6.4 +/- 3.0). Semisynthetic diet also reduced the jejunal villous height significantly when compared with home diet (408 +/- 49 vs. 373 +/- 44 micron). Therefore, on semisynthetic diet the toxicity of dietary xenobiotics that are inactivated by the intestinal mucosa may be increased.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1983

Differences in muscle spindle structure between pigeon muscles used in aerial and terrestrial locomotion.

Muscle spindle density (number of spindles per gram of muscle) of all 29 muscles of the forearm and leg of the domestic pigeon was evaluated by counting receptors in van Gieson-stained serial cross sections. Extra- and intra-fusal fiber-type profiles were determined from histochemical preparations. Muscles of the leg had on the average significantly more avian slow-twitch oxidative extrafusal fibers (22.5 vs. 0.8%) and slower contraction times than muscles of the forearm, but fiber-type profiles and gross actions of muscles showed no consistent relation to the relative abundance of receptors. Differences in intrafusal fiber-type composition among spindles were sought because of their potential effect on the quality of the afferent discharge. The number of intrafusal fibers per spindle was on the average significantly less (4.57 vs 5.99) in the muscles of the leg than in those of the forearm; and of spindles with the same number of intrafusal fibers, those in the leg had smaller periaxial spaces. Distribution of intrafusal fiber types identified with the myofibrillar adenosine triphosphatase reaction differed among spindles of varying sizes. An acid- and alkali-labile type occurred most frequently (P = 0.05) in spindles with one to three intrafusal fibers, and an acid-labile and alkali-stable type was most often seen (P = 0.05) in spindles with 4 to 7 intrafusal fibers. The smaller receptors were more abundant in the leg, while the larger ones were about equally distributed between the two extremities. Muscle fibers with dimensions that sometimes approached small extrafusal fibers were present in about 3% of the axial bundles examined, most of them in the forearm. The selective morphological variation of avian muscle spindles may represent the structural basis for qualitatively different afferent discharges that relate to the characteristic types of locomotion served by the two extremities.

Animals↗
PubMed1982

["Thorakeurynter," a simplification of the postoperative period following pneumonectomy].

Based on the technique described by Gabler et al. several years ago, stabilization of the mediastinum after penumonectomy is obtained by introducing a blown up latex balloon into the operated side of the thorax. The balloon is introduced immediately following surgery after being distended by means of Kuss's apparatus, and is removed, after being emptied in the same way, five to seven days later. Good stabilization of the mediastinum during the immediate postoperative period allows rapid effective coughing to take place. The balloon also prevents postoperative emphysema through the mediastinal and parietal walls, especially in enlarged excisions. The method is of undoubted value in the postoperative period following pneumonectomy, particularly in chronic bronchitis cases. No particular complications were observed.

Humans↗
PubMed1979

Occurrence and distribution of muscle spindles in masticatory and suprahyoid muscles of the rat.

The occurrence and distribution of muscle spindles was studied in histochemically and conventionally stained serial cross sections of 6-week-old and adult rat masticatory and suprahyoid muscles. Spindles were present in moderate to large numbers in jaw closers, but they were absent in jaw openers and two of four muscles of an accessory suprahyoid group. In jaw closers, 67% or more of the total spindle population was concentrated relatively distant from the temporomandibular joint, in muscle portions which contained large numbers of extrafusal fibers reacting strongly for oxidative enzymes. Because of their location, spindles in these portions should be stretched more and, subsequently, should respond with a greater afferent discharge at any given muscle length than spindles situated nearer to the joint. Spindles in jaw closers, especially the medial pterygoid and deep masseter, often occurred in clusters and complex forms near the terminal branching of intramuscular nerve trunks. No such concentrations were seen in the two muscles of the accessory suprahyoid group that had spindles. The association in jaw closers of spindles with extrafusal fibers high in oxidative enzyme activity is consistent with the view that spindles are the sensory component of a reflex system that recruits these fibers for finely-graded contractions in response to small internal length-changes of the muscle (Botterman et al., '78); however, in jaw openers and two muscles of the accessory suprahyoid group, the absence of spindles, coupled with the presence of large populations of extrafusal fibers high in oxidative enzyme activity, is not easily reconciled with this concept.

Animals↗
PubMed1979

The blood supply of muscle spindles in some mammals and the pigeon.

The blood supply of muscle spindles was studied in serial cross sections in macaque, cat, rabbit, guinea pig, mouse and pigeon muscles which had been incubated in a medium containing 3,3' diaminobenzidine. Lumina of blood vessels were recognized by the reaction product that was localized within erythrocytes. The outer capsule was well vascularized, but few or no capillaries were seen in the periaxial space. The inner spindle capsule, which closely invests the axial bundle, was rarely contacted by periaxial capillaries at the equator and juxtequator. Capillaries occurred more frequently adjacent to intrafusal fibers at the polar region and beyond the end of the outer capsule. Shorter diffusion distances and, usually, higher capillary densities were found at the polar region than at the spindle midsection. This suggests that transcapillary exchange at the polar segment is nearer to conditions prevalent in extrafusal muscle than elsewhere in the spindle, provided the inner and outer capsules are not less permeable at the poles than at the midsection. Differences in blood supply among mammalian species appear to be related to receptor size.

Animals↗
PubMed1976

Histological and histochemical comparisons of muscle spindles in three hind limb muscles of the guinea pig.

Guinea pig soleus, medial gastrocnemius and vastus lateralis muscles were compared for spindle density and distribution, number of intrafusal fibers per spindle and histochemical appearance of the axial bundle. A total of 326 spindles was used in the comparisons. Spindle density was over four times greater in the soleus than in either the medial gastrocnemius or vastus lateralis. In the soleus the spindles were distributed at random, but in the other two muscles no spindles were found in those fascicles in which fast-twitch glycolytic extrafusal fibers predominated. The average number of intrafusal fibers per spindle varied by less than 5% between the three kinds of muscles. About 80% of all spindles located had four intrafusal fibers, two of the nuclear bag type and two of the nuclear chain type. The histochemical appearance of the axial bundle was the same in each kind of muscle. Based on intensities of the myofibrillar adenosine triphosphatase reaction product at polar regions nuclear bag fibers were separable into two histochemical groups; nuclear chain fibers were of only one histochemical type.

Adenosine Triphosphatases↗
PubMed1976

Properties of immobilized guinea pig hindlimb muscles.

Guinea pig hindlimbs were unilaterally immobilized at resting length to evaluate histochemical, biochemical, and contractile properties of immobilized muscle. Contralateral limbs remained unrestrained. Four weeks later contractile properties were measured under chloral hydrate anesthesia. Average time-to-peak tension of the immobilized soleus was 30% less, whereas that of the gastrocnemius was not significantly changed relative to contralateral muscles. Immobilized soleus muscles acquired as much as 25% fibers with high alkaline myofibrillar adenosine triphosphatase activity; these fibers do not occur in the normal muscle. Neither the immobilized soleus nor gastrocnemius fatigued more quickly than their contralateral counterparts. In the immobilized gastrocnemius myofibrillar protein (mg/g muscle) decreased to 76% and maximum tetanic tension to 70% of contralateral values. However, tetanic tension per gram wet muscle weight or 100 mg myofibrillar protein was significantly greater in the immobilized gastrocnemius. No specific factor responsible for the increased tetanic tension could be identified.

Adenosine Triphosphatases↗
PubMed1976

[Estimation of cardio-respiratory energy reserves by ergometric exploration].

Beyond the usual respiratory functional tests, ergometry represents a complementary test, yielding much information on the functioning of the lung-heart system. Simultaneous recording, studying and comparing different respiratory and haemodynamic functional parameters during effort, provides an objective appreciation of the cardio-respiratory energetic reserve. Such a study is necessary to estimate a functional handicap and to understand the pathophysiological alterations of the cardio-respiratory system. The estimation of energetic reserve based on the simultaneous study of multiple respiratory and circulatory parameters also provides valuable information. Ergometry is of equal value in the estimation of operating risks in pulmonary surgery. Information drawn from more than 600 ergometric tests composed of simultaneous recording of 8 parameters (heart rate, ECG, pulse volume, spirogram, ventilation per minute, SAO2, capnogram, right ventricular pressure) have confirmed the great value of this method in pulmonary medicine.

Adult↗
PubMed1976

[Growth velocity of breast carcinoma and radiographic "early diagnoses"].

Between 1960 and 1975, 53 mammary carcinomas have been observed in a collective of 15000 women a part of whom, comprising finally 80 per cent, was free from troubles (annual prophylactic examination for breast cancer). Of these 53 cases were available two up to eleven preceding mammographic series made within an observation period of 0.2 to eleven years. A "mean growth curve" was obtained empirically, based on 163 mammographic tumor measurements with tumor sizes between 2 mm and 60 mm. In the course of a development period between two and eleven years, 33 per cent of the carcinomas were seen to accelerate their further growth in comparison with the initial value; 66 per cent revealed an increasing slow-down of growth, and all tumors showed considerable changes in their growth rates. Mammary carcinomas altogether continually decelerated their growth as measured by the duplication time of the tumor volume from Tv = 309 days on the average up to an average of Tv = 381 days after two through eleven years. The mean growth curve exhibited an exponential shape which was completed by biomathematical methods and can be described by means of a Power function. It corresponds well to the rate of incidence of the mammary carcinoma which shows an identical rise in relation to increased old age. The medium growth time from a primary cancerous cell with ten micron in size up to the tumor 2 mm in diameter may be estimated biomathematically only and amounts to ten or twenty years with 23 duplication periods. The further average growth rate between the tumor sizes of two and ten millimeter, stages which can be diagnosed roentgenologically, was empirically six years; the most quickly growing tumor needed almost two years. For the purpose of early cancer detection (tumor size below 10 mm, lymph nodes histologically free from metastases), the serial mammography to be performed every 18 months or two years is the only technique which provides utilizable early recognition marks and besides does allow a simple judgement. Solely the symptoms "suspect desification, partly spiculated" in sixty per cent and "typical cancerous microcalcification" in forty per cent have been observed as the earliest signs. The reliability ("certainty") of mammography is frequently overestimated (false negative rate: 7 to 18%) and should be quoted only for collectives where control mammographies have been made over a period of five or ten years. Roentgenological controls of alterations below three millimeter in size and without an indication for biopsy ought to be performed within six months, and still sooner in case of larger alterations. It is not possible earlier than after five or ten years to judge of the radicality of a therapy, as spread cancerous cells, on he average, reveal similar growth rates as does the primary tumor.

Adult↗