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Biomedical subjects

P Meier

Publications and source records attributed to P Meier.

At least 163 records · Page 9Linked to original sources
PubMed1982

Staging of breast cancer and survival rates. An assessment based on 50 years of experience with radical mastectomy.

The correlation of staging criteria for mammary carcinoma with the curability of primary and recurrent local and regional lesions was assessed by follow-up after 1,259 consecutive radical mastectomies performed in women under age 70 between 1927 and 1978. Using a staging scheme revised in the light of our experience, the incidence of recurrence by 20 years was 34% +/- 2.7% for pathological stage I, 65% +/- 2.6% for stage II, and 83% +/- 2.5% for stage III. Recurrence after 20 years was observed in one of 178 patients. After treatment of local recurrence, three of 51 patients survived 20 years. By restriction of entry into clinical or pathological stages I and II, currently employed revisions of staging criteria appear to increase survival in all stages, while placing patients with possibly curable lesions in stages III and IV.

Adult↗
PubMed1982

Structure and dynamics of phospholipid membranes: an electron spin resonance study employing biradical probes.

The large zero-field splitting of rigid biradicals makes them important candidates for spin probes of phospholipid membranes. Here we develop an electron spin resonance line-shape model for such probes on the basis of the stochastic Liouville equation. Particular emphasis is given to the slow-diffusional regime, characteristic of bilayers in the gel phase. The theory is employed to study the line shapes of bis(verdazyl) biradicals, incorporated into oriented multibilayers of dimyristoylphosphatidylcholine. Computer simulations of the angular-dependent spectra provide the orientational distribution functions and rotational correlation times of the spin probes. They occupy two different sites in bilayer membrane. The orientational distribution of the spin probes is related to the structure of the phospholipid phases. In the L beta' phase the hydrocarbon chains are uniformly tilted by delta = 23 degrees with respect to the bilayer normal. For the P beta' phase we observe a random distribution of tilt angles from delta = 0 degree to delta = 19 degrees, indicating that the chains orient perpendicular to the local (rippled) bilayer surfaces. This structure has not been established previously. In agreement with other studies we find no tilt for the L alpha phase. The order parameters of the hydrocarbon chains increase with decreasing temperature, jumping from S less than or equal to 0.6 to S greater than or equal to 0.8 at the main transition. From the rotational correlation times of the spin probes, intrinsic bilayer viscosities of 0.08 P less than or equal to eta less than or equal to 20 P (50 degrees C greater than or equal to T greater than or equal to 1 degree C) are determined. An Arrhenius plot provides activation energies of the viscous flow. The values increase from Evisc approximately 10 kcal/mol in the L alpha phase to Evisc approximately 18 kcal/mol in the L beta' phase.

Dimyristoylphosphatidylcholine↗
PubMed1982

Current research in statistical methodology for clinical trials.

Statistical Methodology for Clinical Trials has advanced primarily in those domains opened up by the advent of high speed computation. Data acquisition, data management, and data monitoring have been revolutionized, and statistical analysis in clinical trials has advanced from simple cross tabulation and lists of averages to the use of special regression and other methods for estimation and for covariance adjustment. Research on sequential designs has had little effect on practice, largely because the usual sequential methods fail to address the key problems posed by ethical constraints, but a related development of research on "stopping rules" seems promising. Although considerable attention has been given to the problems of multiplicity--analysis of subgroups, choice of endpoints, post-randomization exclusions--little progress in this area has been made as yet. The paper explores these issues in some detail with the aid of illustrative examples.

Aspirin↗
PubMed1982

A statistical analysis of the loss of muscle strength in Duchenne's muscular dystrophy.

We have confirmed that the loss of muscle strength in 12 boys with Duchenne's muscular dystrophy, as measured by manual muscle testing, approximates a linear decay model, but we have also found that it fits as well a first order decay model. The strength in the same eight muscles was measured over time. Results of an analysis of 111 examinations are reported here. An arbitrary numerical scale for grading muscle strength was used, such that normal was 13 units, and no movement was zero. The maximal sum, if all 8 muscles were normal, would be 104 units. Pooling all measurements, the linear decay rate in this sum was -0.189 +/- 0.023 (estimate +/- standard error) arbitrary muscle strength units . month-1. The corresponding first order fractional decay rate was -0.0034 +/- 0.0004 month-1. However, a more detailed statistical analysis indicated that decay rates in muscle strength were not homogeneous, i.e. muscle strength decayed faster in some patients than others. The decay constants in 11 of the 12 subjects spanned a 10-fold range, and in one subject increased the spread to 40-fold. The distribution frequency of decay rates appears to be bimodal. In these assessments, the muscle strength at time zero was not known. Therefore, an estimate of muscle strength at 10 years was made. This varied from 34 to 71 units. The group mean was 53.0 units using the exponential model, i.e. on average, only 51% (= 53.0/104 X 100) of the normal muscle strength remained in the 8 muscle groups assessed at age 10 years. In conclusion, a quantitative characterization of muscle strength deterioration is reported, which emphasizes the heterogeneity in this disease. This approach may eventually allow quantitative distinctions between Duchenne's and Becker's varieties of muscular dystrophy.

Adolescent↗
PubMed1981

Relationship between amino acid intake and accretion in a marsupial, Macropus eugenii. I. Total amino acid composition of the milk throughout pouch life.

The total amino acid composition of 57 samples of milk was analyzed by ion exchange resin chromatography after acid hydrolysis of proteins. The concentrations of most of the amino acids in the milk increased in proportion to the increase in milk protein. Sharp increases in the sulfur-containing amino acids, cystine (and/or cysteine) and methionine occurred at around 140-160 days which is about the time of hair follicle development. The remaining amino acids reached a peak concentration by 220 days, by which stage of development the pouch young has fully developed homeothermy. These higher amino acids levels were sustained to day 260, the time of highest milk protein concentration. The amino acids provided in the milk to the suckling pouch young thus show changes in relative amounts which correlate with some of the developmental events occurring during this phase of active growth and maturation.

Aging↗
PubMed1979

Psychological development of children who received intrauterine transfusions.

The intellectual, visual-motor, and social development of 15 children, 3 to 10 years of age, who received IUT for eythroblastosis fetalis was compared with that of 15 children of similar age who had required only exchange transfusions for the treatment of the same disorder. No over-all differences were found between the two groups or between the groups and the normal population. In comparison with normal population, recipients of IUT have above average IQ's and normal development in visual-motor integration and adaptive behavior.

Adaptation, Psychological↗
PubMed1979

Terminating a trial -- the ethical problem.

A comparative clinical trial will often lead to the conclusion that one regimen is clearly better than another. Should the estimated difference in the regimens be large and precisely determined, continuation of the trial would constitute abuse of the participants. Some earlier proposals for ethical decision making on continuing a trial are shown to be unsatisfactory, and a more general framework for dealing with the problem is proposed.

Clinical Trials as Topic↗
PubMed1978

[Therapy of the unstable thorax in serial fractures of the ribs].

The histories of patients with flail chest and respiratory insufficiency caused by blunt chest injury have been analyzed. The first group represented patients with surgical stabilization of 3-4 ribs by introduction of "Rehbein plates" into the medullary cavity (10 patients 1972-1975). The patients of the second group have been supported by controlled mechanical respiration (11 patients 1972-1975). Patients with chest and further injuries (polyblessés) of comparable degree have been selected for both groups. The two groups were compared with regard to duration of intubation and artificial ventilation (average of 8.8 days for the operated and 21.4 days for the mechanically ventilated patients), stay in the intensive care unit (15.2 days after operation and 28.3 days for treatment by respirator) and average total hospitalization time (33.5 days after surgical management and 54.2 days after nonsurgical treatment). Severe bronchial infections caused by hospital germs have occurred more frequently in patients on long-term intubation and mechanical respiration. The average age of patients was almost the same in both groups. The technique of surgical stabilization of the ribs is described, and the advantages and limits of surgical and conservative management of respiratory insufficiency caused by flail chest are discussed.

Adult↗