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Biomedical subjects

D Klein

Publications and source records attributed to D Klein.

At least 37 records · Page 2Linked to original sources
PubMed1990

Quantitation of Cu-containing metallothionein by a Cd-saturation method.

A rapid and sensitive method for determining Cu-containing metallothionein (MT) is described. The main features of this Cd-saturation assay are: high-molecular-weight Cd-binding compounds are denatured with acetonitrile (50% final concentration), Cu bound to MT is removed with ammonium tetrathiomolybdate, excessive tetrathiomolybdate and its Cu complexes are removed with DEAE-Sephacel, apothionein is saturated with Cd, and excessive Cd is bound to Chelex 100. The thiomolybdate assay is capable of reliably detecting 14 ng MT and thus is particularly suitable for measuring MT in small tissue samples (e.g., biopsies), in extrahepatic tissues, and in cultured cells. Moreover, the combination of the thiomolybdate assay with the recently developed Cd-Chelex assay also makes it possible to determine the portion of MT which binds Cu (Cu load of MT), provided that the amount of non-Cu-thionein exceeds 100 ng, the detection limit of the Cd-Chelex assay.

Animals↗
PubMed1990

The Cd-Chelex assay: a new sensitive method to determine metallothionein containing zinc and cadmium.

A rapid and sensitive one-vial procedure to determine metallothionein (MT) containing zinc (Zn) and cadmium (Cd) is described. New features of this Cd-saturation method are: high molecular weight Cd-binding proteins are denatured by treatment with acetonitrile (50% final concentration), and excess of Cd is bound to a cation exchange resin (Chelex-100). With this method, MT has been measured, e.g. in liver of control and zinc- or cadmium-treated rats, in human liver and in cultured human fibroblasts down to absolute amounts of 0.1 microgram. The Cd-Chelex assay is 10 times more sensitive than the established Cd-heme assay (Dieter et al. 1986) and therefore is particularly suitable to quantify MT in small tissue samples (e.g., liver biopsies of a few milligrams) and in extrahepatic tissues or cell cultures with low MT concentrations.

Adolescent↗
PubMed1990

Longitudinal change in HIV transmission risk behaviors by gay male physicians.

Gay male physicians were surveyed in 1984 and 1985 about their knowledge and attitudes regarding HIV transmission and AIDS and changes they had made in social, health-related, and sexual activities since the onset of the AIDS epidemic. Most of the 37 subjects who participated in both surveys progressively lessened their participation in HIV transmission risk behaviors over time. Health belief, AIDS knowledge, health coping, social support, mood state, and age factors all contributed to changes in sexual behavior. The modeling of sexual-behavior changes showed general stability over time. This study provides further evidence that multiple psychosocial factors are associated with changes in sexual behavior, even in gay male physicians.

Adult↗
PubMed1990

[Development of genetic research in ophthalmology with special reference to Switzerland].

The relationship between ophthalmology and genetics has always been a very active one, and existed even before Mendel's laws of inheritance were known. The pedigree method in particular yielded satisfactory results even to the first researchers. Later, Helmholtz's invention of the ophthalmoscope (in 1851) and the rediscovery of Mendel's laws of heredity (in 1900) made major contributions to the progress of human genetics in ophthalmology. Credit is due to J. F. Horner of Zurich (1831-1886) for having first established the X-chromosomal inheritance of colorblindness. Subsequently, the development of genetic research was advanced in particular by Alfred Vogt, Professor of Ophthalmology in Zurich (1879-1943) and Adolf Franceschetti in Geneva (1896-1968) and their co-workers. We are indebted to Vogt for the first description of albinismus solum bulbi. Credit is also due to him for having made early diagnosis of myotonic dystrophy (Steinert) possible, a major discovery for genetic counseling. He was the first to detect, by slit-lamp examination, characteristic lens changes in the form of whitish, red, and green opacities in the anterior and posterior subcapsular regions. Franceschetti's achievements include the description of several clinical syndromes, of which mandibulofacial dysostosis has become well known. Among the hereditary retinal dystrophies, he described fundus flavimaculatus (yellowish lesions disseminated in the deeper layers of the posterior pole) as a new entity, attributed to degeneration of the pigment epithelium. In addition to more than 500 articles, he was also co-author, with J. François and J. Babel, of a monumental handbook in two volumes titled Hérédodégénérescences choriorétiniennes (of which an English translation appeared in 1974).(ABSTRACT TRUNCATED AT 250 WORDS)

Eye Diseases↗
PubMed1990

Evolution of the class II major histocompatibility complex alleles in higher primates.

We have shown that chimpanzees and gorillas have DRB alleles very similar to those of humans. The existence of similar DRB alleles in the different species of higher primates cannot be accounted for by convergent evolution of unrelated alleles that arose independently after the speciation. We therefore conclude that ancestral DRB alleles, that had existed before the speciation, were transmitted to the ancestors of humans, chimpanzees, and gorillas. This conclusion indicates that the diversification of MHC alleles does not start at the inception of a species, but rather proceeds beyond the lifespan of a species. A high degree of sequence similarity found between certain human and non-human primate DRB alleles shows that MHC alleles do not diversify rapidly. The bulk of the contemporary DRB polymorphism seems to have been generated by accumulation of random point mutations during long evolutionary periods preceding the divergence of humans, chimpanzees, and gorillas.

Alleles↗
PubMed1990

Cytomegalovirus infection in a neonatal intensive care unit. Subsequent morbidity and mortality of seropositive infants.

In a study of blood transfusion and cytomegalovirus (CMV) infection in 385 infants, 5 (8%) of 60 seropositive infants with birthweights less than or equal to 1250 g acquired CMV. Four infants had become seronegative by the time of viral excretion and demonstrated significant morbidity with one death. Morbidity included variant (atypical) lymphocytosis, thrombocytopenia, Staphylococcal epidermidis and Candida parapsilosis infections, and respiratory deterioration. Interestingly, the infant who exhibited only minimal morbidity was seropositive at the time of viral excretion. CMV seropositivity at birth may not protect low birthweight (LBW) infants from the morbidity and mortality associated with CMV infection.

Antibodies, Viral↗
PubMed1989

Shared class II MHC polymorphisms between humans and chimpanzees.

To gain an insight into the evolution of the major histocompatibility complex alleles, three DRB and one DRA genes were isolated from chimpanzee cDNA libraries. The nucleotide sequences of the chimpanzee DRB (ChLA-DRB) genes were then compared with those of the available HLA-DRB alleles by constructing unrooted phylogenetic trees. All three ChLA-DRB genes were found to be more closely related to certain HLA-DRB alleles than unrelated HLA-DRB alleles are to each other. Since available evidence does not support the convergent evolution of MHC alleles, this result is consistent with the idea that closely related ChLA-DRB and HLA-DRB alleles are derived from common ancestral alleles, the existence of which predates the divergence of human and chimpanzee lineages. The predicted amino acid sequences of mature ChLA-DRA and HLA-DRA molecules differ by only one amino acid.

Amino Acid Sequence↗
PubMed1989

Differential expression of the two human arginase genes in hyperargininemia. Enzymatic, pathologic, and molecular analysis.

Previous studies in our laboratory and others have demonstrated in humans and other mammals two isozymes of arginase (AI and AII) that differ both electrophoretically and antigenically. AI, a cytosolic protein found predominantly in liver and red blood cells, is believed to be chiefly responsible for ureagenesis and is the one missing in hyperargininemic patients. Much less is known about AII because it is present in far smaller amounts and localized in less accessible deep tissues, primarily kidney. We now report the application of enzymatic and immunologic methods to assess the independent expression and regulation of these two gene products in normal tissue extracts, two cultured cell lines, and multiple organ samples from a hyperargininemic patient who came to autopsy after an unusually severe clinical course characterized by rapidly progressive hepatic cirrhosis. AI was totally absent (less than 0.1%) in the patient's tissues, whereas marked enhancement of AII activity (four times normal) was seen in the kidney by immunoprecipitation and biochemical inhibition studies. Immunoprecipitation-competition and Western blot analysis failed to reveal presence of even an enzymatically inactive cross-reacting AI protein, whereas Southern blot analysis showed no evidence of a substantial deletion in the AI gene. Induction studies in cell lines that similarly express only the AII isozyme indicated that its activity could be enhanced severalfold by exposure to elevated arginine levels. Our findings suggest that the same induction mechanism may well be operative in hyperargininemic patients, and that the heightened AII activity may be responsible for the persistent ureagenesis seen in this disorder. These data lend further support to the existence of two separate arginase gene loci in humans, and raise possibilities for novel therapeutic approaches based on their independent manipulation.

Arginase↗
PubMed1989

Leber's congenital amaurosis associated with high hyperopia in four sisters.

The authors describe a family with five daughters, of whom four are affected with Leber's congenital amaurosis and high hyperopia ranging between +5.5 and +9 diopters. In addition, the second daughter is a little short for her age, and shows a slight dyscrania with prominent frontal and occipital bones, hypoplasia of the nasal bone, and deep and narrow orbits leading to marked enophthalmos. The symptoms are typical of Leber's amaurosis. All children have nystagmus, night blindness, weak or absent pupillary reflexes. Visual fields are constricted or not measurable. The electroretinogram is extinguished, and hyperopia of the axial type was confirmed by ultrasound. Fundus findings are variable with small, pale and somewhat protruding papillae (pseudo-papillitis), narrow retinal vessels, diffuse fundus pigmentation of pepper-and-salt type and unusual yellow coloration of the macular region (diffuse atrophy). The inheritance of Leber's congenital amaurosis is autosomal recessive. The combined occurrence of amaurosis and hyperopia in four children in one family, while the fifth is unaffected and has no refractive error, furnishes a further evidence for the existence of a particular amaurosis-hyperopia subtype of Leber's disease.

Blindness↗
PubMed1988

I.29 lymphoma cells express a nonmutated VH gene before and after H chain switch.

The I.29 B cell lymphoma consists of IgM+ and IgA+ cells which express the same germ-line VH gene. IgA+ cells of the I.29 lymphoma were derived from the IgM+ cells by a typical H chain switch recombination event. The IgM+ cells can be induced with LPS to undergo H chain switching in culture. It has been proposed that the somatic hypermutation process is activated during H chain switch, since V genes expressed in IgG+ and IgA+ cells have more frequently undergone mutation than those expressed in IgM+ cells. We have investigated this question by sequencing VH genes expressed before and after H chain switch in the I.29 lymphoma. We have also sequenced the germ-line VH gene corresponding to the gene expressed by I.29 cells to determine whether the VH gene expressed in the IgM+ cells had already undergone somatic mutation. Our results indicate that somatic mutation was not activated in the precursor cell for the I.29 lymphoma, nor during isotype switch in I.29 cells. It is possible that cells of the I.29 lymphoma, or their precursor, have not received the signal which induces somatic mutation, or that I.29 cells belong to a subset of B cells that cannot be induced to undergo any (or much) somatic mutation.

Amino Acid Sequence↗
PubMed1988

Cytomegalovirus infection in a neonatal intensive care unit. Blood transfusion practices and incidence of infection.

We studied blood transfusion variables and cytomegalovirus (CMV) infection in 385 infants admitted to the Duke University Medical Center, Durham, NC, neonatal intensive care unit over 14 months. Cytomegalovirus antibody titers were measured at birth and monthly thereafter. Urine cultures for CMV were performed regularly. Infants admitted in the first six months (n = 197) received conventionally prepared blood. Infants admitted in the remaining eight months (n = 188) were given frozen, deglycerolized blood. Of the 105 infants weighing 1250 g or less (low birth weight [LBW]), 90 (86%) received transfusions. Two hundred eighty infants weighed more than 1250 g (non-LBW), and 111 (40%) of these were given blood. In the first six months of the study, three infants had CMV viruria. One case was congenital; two were acquired. Both infants who acquired infection were antibody-positive at birth and received multiple transfusions. In the remaining eight months, five infants had CMV viruria. Two cases were congenital; three were acquired. The three infants who acquired infection were antibody-positive at birth and received multiple transfusions. Our study demonstrates that infants with an LBW are more likely to receive blood transfusion and to be given significantly more blood than non-LBW infants. There was no difference in the number of infants acquiring CMV in the two periods despite the use of different preparations of blood.

Antibodies, Viral↗
PubMed1988

Nucleotide sequences of chimpanzee MHC class I alleles: evidence for trans-species mode of evolution.

To obtain an insight into the evolutionary origin of the major histocompatibility complex (MHC) class I polymorphism, a cDNA library was prepared from a heterozygous chimpanzee cell line expressing MHC class I molecules crossreacting with allele-specific HLA-A11 antibodies. The library was screened with human class I locus-specific DNA probes, and clones encoding both alleles at the A and B loci have been identified and sequenced. In addition, the sequences of two HLA-A11 subtypes differing by a single nucleotide substitution have been obtained. The comparison of chimpanzee and human sequences revealed a close similarity (up to 98.5%). The chimpanzee A locus alleles showed greatest similarity to the human HLA-A11/A3 family of alleles, one of them being very close to HLA-A11. Similarly, segments of the ChLA-B alleles displayed greatest similarity to certain HLA-B alleles. The calculated evolutionary branch point for the A11-like alleles is 7 x 10(6) to 9 x 10(6) years, whereas the other A locus alleles diverged between 12 x 10(6) and 17 x 10(6) years ago. Since the human and chimpanzee lineages separated 5 x 10(6) to 7 x 10(6) years ago, our data support the notion that during evolution, MHC alleles are transmitted from one species to the next.

Alleles↗
PubMed1988

Serum and quantitative electroencephalographic pharmacokinetics of loprazolam in the elderly.

This study was undertaken to determine the serum pharmacokinetic parameters of loprazolam, a new benzodiazepine hypnotic, in elderly subjects and to compare these with the kinetics of the drug as determined by quantitative EEG analysis. In addition, a 14-day study was undertaken to determine the steady-state serum levels achieved in this population with repeated drug administration. The study was conducted on 16 male and female subjects between the ages of 62 and 72 years, randomly assigned to two groups treated with 0.5 or 1.0 mg of loprazolam. The serum half-life of loprazolam was found to be 5 hours, and the peak serum concentration was reached after 2 hours. Quantitative EEG changes were observed after 30 minutes suggesting rapid access of the drug into the nervous system. Quantitative EEG changes were evident for 9.5 hours, suggesting the persistent effects of an active metabolite. The 14-day study indicated that loprazolam did not accumulate with continued use.

Aged↗
PubMed1988

Both GA2, GM2, and GD2 synthases and GM1b, GD1a, and GT1b synthases are single enzymes in Golgi vesicles from rat liver.

Competition experiments using lactosylceramide, ganglioside GM3 and ganglioside GD3 as substrates, as well as mutual inhibitors for ganglioside N-acetylgalactosaminyltransferase, in Golgi vesicles derived from rat liver suggested that N-acetylgalactosamine transfer to these three respective compounds, leading to gangliosides GA2, GM2, and GD2, respectively, is catalyzed by one enzyme. Analogous studies with gangliosides GA1, GM1, and GD1b as glycolipid acceptors in sialyltransferase assays indicated GM1b, GD1a, and GT1b synthases to be identical. These results are incorporated into a model for ganglioside biosynthesis and its regulation.

Algorithms↗