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Biomedical subjects

R M Schmidt

Publications and source records attributed to R M Schmidt.

14 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

[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↗
PubMed1977

Hemoglobin Lufkin: beta 29 (B11) Gly replaced by Asp. An unstable hemoglobin variant involving an internal amino acid residue.

Hemoglobin Lufkin was found in a Black-American family. Structural analysis of the abnormal hemoglobin indicates a substitution of aspartic acid for glycine at position 29 in the beta chain. Marked instability of the variant hemoglobin is demonstrated by the rapid formation of inclusion bodies upon exposure of the red cells to redox dyes and by the large percentage of precipitated hemoglobin at 65 degrees C. The oxygen affinity, the Bohr effect, and the degree of cooperativity of Hb Lufkin and Hb A are similar over the physiologic pH range. However, at acid pH the oxygen affinity of the variant is increased. Unlike several other reported variants in the B helix, Hb Lufkin is not associated with methemoglobinemia.

Amino Acids↗
PubMed1976

Hemoglobin Fannin-Lubbock [alpha2 beta 2 119 (GH2) Gly replaced by Asp]. A new hemoglobin variant at the alpha1 beta 1 contact.

Hemoglobin Fannin-Lubbock was found in a 9-year-old Mexican-American female. The abnormal hemoglobin was detected as a fast-moving variant by electrophoresis on cellulose acetate at pH 8.4. Structural analysis indicated a substitution in the beta-chain of aspartic acid for glycine at position 119, a position involved in the alpha1beta1 contact of the hemoglobin tetramer. This contact between unlike chains is larger and undergoes a smaller shift during the process of oxygenation and deoxygenation that the alpha1beta2 contact (Perutz, M.F., Muirhead, H., Cox, J.M. and Goaman, L.C.G. (1968) Nature 219, 131-139). Mutations in this contact tend to cause slight or no changes in functional behavior. Apart from a mild anemia, the propositus did not exhibit any obvious clinical symptoms.

Amino Acids↗
PubMed1976

Immuneglobulin investigations in inflammatory diseases.

1. The agar electrophoresis of the cerebrospinal fluid and the quantitative immune globulin determination contribute essentially to an assessment of the immunity state in inflammatory diseases of the CNS. 2. It is necessary to distinguish protein augmentation due to brain-barrier disturbances (accompanying proteinosis of the cerebrospinal fluid), which we find in metabolic and traumatic diseases, from a genuine increase in cerebrospinal fluid protein. 3. Autochthonous formation of cerebrospinal fluid protein can be demonstrated by means of quantitative IgG, IgA and gamma3-globulin determination.

Blood-Brain Barrier↗