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Biomedical subjects

R M Schmidt

Publications and source records attributed to R M Schmidt.

At least 19 recordsLinked to original sources
PubMed1979

Quantitation of hemoglobin A2. An interlaboratory study.

In the 1976 hemoglobinopathy proficiency testing survey of the Center for Disease Control (CDC), whole-blood samples from hematologically normal adults and from individuals heterozygous for beta-thalassemia were shipped to survey participants. The object of this survey was to determine the state of the art for technics used to quantitate hemoglobin A2 (Hb A2) and to test the ability of laboratories to differentiate between blood samples having normal Hb A2 levels and those having elevated levels (i.e., those from individuals with beta-thalassemia trait). The results of Hb A2 quantitation obtained from 183 volunteer participant laboratories were compared with those obtained from 24 reference laboratories. Individual values varied greatly among laboratories and among methods for both normal and elevated Hb A2 samples. The results returned by many laboratories were not within 2 SD of the reference laboratory mean and also were not sufficiently accurate to differentiate between the normal blood samples and those with beta-thalassemia trait. The results suggest that methods for quantitating Hb A2 need to be standardized and a suitable method for determining laboratory performance found.

Blood Chemical Analysis↗
PubMed1979

Quantitation of hemoglobin F. An interlaboratory study.

Samples of whole blood from four hematologically normal adults and from two individuals with increased fetal hemoglobin levels were shipped to laboratories participating in the 1976 and 1977 Center for Disease Control (CDC) hemoglobinopathy proficiency testing surveys. The data from these surveys were used to evaluate the interlaboratory variability of current methods used to quantitate hemoglobin F (Hb F). Results of Hb F quantitation obtained from more than 100 laboratories than voluntarily participated in the survey were compared with those obtained from 21 reference laboratories. Individual values for all samples varied greatly among laboratories and among methods. Results returned by most of the laboratories were outside two standard deviations of the reference laboratory mean and were not accurate enough to differentiate between a normal level and an increased, abnormal level.

Fetal Hemoglobin↗
PubMed1979

[Diagnosis of spinal diseases by cerebrospinal fluid examination].

In this work, changes in the cerebrospinal fluid in acute and chronic polyneuritis as well as in the Guillan-Barré-Strohl syndrome are discussed and and it is pointed out that a specific coordination of the inflammatory cerebrospinal fluid syndromes to certain pathogens or noxae cannot be made. For the differentiation of the Guillain-Barré-Strohl syndrome and existence of increased gamma-globulin bands with identical mobility in the serum is pointed out. In myelitic disease pictures, acute and chronic cerebrospinal fluid syndromes are distinguished also in the cerebrospinal fluid according to the clinical course; regular changes, however, cannot be derived. Syphilitic cerebrospinal-fluid syndromes can easily be differentiated by their immunoactive findings. In multiple sclerosis, we distinguish between typical and atypical changes in the cerebrospinal fluid. Above all, the oligoclonal bands, i. e. the discontinuous proceeding of the gamma-globulin zone and the existence of several bands in the agar gel electrophoresis, play an essential role. In 95 per cent of the cases, oligoclonal bands can be shown. There are no greater differences with respect to oligoclonal bands between intermittent and chronic-progressive courses. For the differential diagnosis of haemorrhagic syndromes, the cerebrospinal fluid cell picture can make a considerable contribution. Macrophages loaded with erythrocytes indicate that a haemorrhage occurred 12 to 18 hours before; macrophages loaded with haemosiderin indicate a haemorrhage that occurred 6 to 8 days before; and macrophages loaded with erythrocytes and haemosiderin indicate a seeping haemorrhage or an event that occurred several times. The Nonne-Froin syndrome indicates a massive protein increase often with a regular or only slightly increased number of cells. The importance of the Queckenstedt tests is pointed out. A particular role is played by meningitis carcinomatosa et sarcomatosa with the demonstration of a great number of tumour cells.

Diagnosis, Differential↗
PubMed1978

Stigmatization of carrier status: social implications of heterozygote genetic screening programs.

Possible latent psychological and social consequences ensuing from genetic screening programs need to be investigated during the planning phase of national genetic screening programs. The relatively few studies which have been performed to determine psychological, social, and economic consequences resulting from a genetic screening program are reviewed. Stigmatization of carrier-status, having major psychosocial implications in heterozygote genetic screening programs, is discussed and related to Erving Goffman's work in the area of stigmatization. Questions are raised regarding the relationship between such variables as religiosity and sex of the individual and acceptance of the status of newly identified carrier of a mutant gene. Severity of the deleterious gene and visibility of the carrier status are two important factors to consider in an estimation of potential stigma. Specific implications are discussed for four genetic diseases: Tay-Sachs, Sickle-Cell Anemia, Huntington's disease and Hemophilia.

Anemia, Sickle Cell↗
PubMed1978

Microchromatographic methods for hemoglobin A2 quantitation compared.

On 20 consecutive work days during four weeks, one technologist performed 24 microchromatographic determinations of hemoglobin A2 (Hb A2) by each of four methods: the Efremov procedure requiring Tris/HCl buffer, the original Huisman technique with use of glycine developer, and two commercial test kits in which a modified glycine developer is used. The bloood samples tested were obtained from 12 adults with no hematological abnormality and from 12 beta-thalassemia carriers previously diagnosed by familial and hematologic studies. Results by the first method and the two commercial kits (one from Helena Laboratories and one from Isolab, Inc.) did not differ significantly in precision for either the normal or beta-thalassemia trait samples. For both sample types, the second method yielded larger coefficients of variation than those obtained with the other methods. Moreover, the second method was the only one with which values overlapped for normal samples and samples with above-normal Hb A2 concentrations.

Chromatography, Ion Exchange↗
PubMed1978

Cell regulations of the cerebrospinal fluid in diseases of the central nervous system.

After a survey of the composition and the possibilities of the differentiation of the liquor cytogram, the author reports upon the reaction types of the cerebrospinal fluid. Following the functional mechanisms of the cerebrospinal fluid cells (phagocytosis, digestion, thesaurismosis, formation of antibodies) are to be mentioned.

Antibody Formation↗
PubMed1978

[Cerebellopontile angle symptomology in plasmocytoma: a case report].

The author reports on a patient with cerebellopontile angular symptomatology in the case of a plasmocytoma. The diagnosis of plasmocytoma was established from the pathological results of gamma globulin subfractionation and immune electrophoresis. Also commented in this discussion is the problem of essential cryptogenetic paraproteinosis.

Cerebellar Neoplasms↗
PubMed1978

[Remarks on fluorescence microscopy of cerebrospinal fluid cells (author's transl)].

Fluorescencemicroscopic investigations of the liquor cells were carried out by acriclinorange, trypaflavea, the fluorescence component of anilinblue and morin in connection with thiacinred. After that it will be reported about microscopphotometrical measure ments and examinations of immunfluorescence and emphasized the importance of these methods for cytochemistry of the cerebrospinal fluid.

Antigen-Antibody Reactions↗
PubMed1978

CSF -- oligoclonal bands in multiple sclerosis.

The present paper is concerned with a correlation between clinical parameters of multiple sclerosis and different agar gel electrophoretical patterns in CSF. The agar gel electrophoresis represents clearly the most sensitive method for the demonstration of oligoclonal bands in CSF.

Adult↗
PubMed1977

Hemoglobin S Travis: a sickling hemoglobin with two amino acid substitutions [beta6(A3)glutamic acid leads to valine and beta142 (h20) alanine leads to valine).

Hb S Travis is a previously undescribed sickling hemoglobin with two amino acid substitutions in the beta chain: beta6 Glu leads to Val and beta142 Ala leads to Val. The beta6 Glu leads to Val mutation imparts to Hb S Travis the characteristic properties of sickling hemoglobin, namely its association with erythrocyte sickling, the insolubility of the hemoglobin in the reduced form, and a minimum gelling concentration value identical to Hb S. Unlike Hb S, Hb S Travis exhibits an increased oxygen affinity and a decreased affinity for 2,3-bisphosphoglycerate and inositol hexakisphosphate. In addition, the variant hemoglobin's tendency to autoxidize and its mechanical precipitability suggest that there are conformational differences between Hb S and Hb S Travis.

Alanine↗
PubMed1977

Hemoglobin Tarrant: alpha126(H9) Asp leads to Asn. A new hemoglobin variant in the alpha1beta1 contact region showing high oxygen affinity and reduced cooperativity.

Hemoglobin (Hb) Tarrant was detected by its electrophoretic mobility on cellulose acetate (pH 8.4) and citrate agar (pH 6.2). On cellulose acetate it moved as a band between hemoglobins F and S, and on citrate agar as a band at hemoglobin S. The test for solubility in 2 M phosphate buffer with Na2S2O4 was negative. The new variant has a substitution of asparagine for aspartic acid in position 126 of the alpha-chain, one of the sites involved in the alpha1beta1 contact. Furthermore, in deoxyhemoglobin aspartic acid 126 of each alpha chain also forms a non-covalent electrostatic salt bridge with arginine 141 of the corresponding alpha chain (Perutz, M. F. and Ten Eyck, L. F. (1972) Cold Spring Harbor Symp. Quant. Biol. 36, 295-310 and Perutz, M. F. (1970) Nature 228, 726-739). As a consequence of this substitution in hemoglobin Tarrant, the deoxy conformation or T state is destabilized because these two bridges cannot be formed. This condition is reflected in high oxygen affinity and low cooperativity.

Amino Acid Sequence↗