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Biomedical subjects

J Klein

Publications and source records attributed to J Klein.

At least 343 records · Page 19Linked to original sources
PubMed1995

Phylogenetic analysis of cichlid fishes using nuclear DNA markers.

The recent explosive adaptive radiation of cichlids in the great lakes of Africa has attracted the attention of both morphologists and molecular biologists. To decipher the phylogenetic relationships among the various taxa within the family Cichlidae is a prerequisite for answering some fundamental questions about the nature of the speciation process. In the present study, we used the random amplification of polymorphic DNA (RAPD) technique to obtain sequence differences between selected cichlid species. We then designed specific primers based on these sequences and used them to amplify template DNA from a large number of species by the polymerase chain reaction (PCR). We sequenced the amplified products and searched the sequences for indels and shared substitutions. We identified a number of such characters at three loci--DXTU1, DXTU2, and DXTU3--and used them for phylogenetic and cladistic analysis of the relationships among the various cichlid groups. Our studies assign an outgroup position to Neotropical cichlids in relation to African cichlids, provide evidence for a sister-group relationship of tilapiines to the haplochromines, group Cyphotilapia frontosa with the lamprologines of Lake Tanganyika, place Astatoreochromis alluaudi to an outgroup position with respect to other haplochromines of Lakes Victoria and Malawi, and provide additional support for the monophyly of the remaining Lake Victoria haplochromines and the Lake Malawi haplochromines. The described approach holds great promise for further resolution of cichlid phylogeny.

Africa, Eastern↗
PubMed1995

Predictive value of postmyelographic computed tomography for patients with severe postmyelographic headache.

Our goal was to determine if evidence of cerebrospinal fluid (CSF) leakage on routine postmyelogram computed tomography (CT) of the lumbar spine was useful in predicting subsequent development of moderate or severe headaches in patients having outpatient myelography. We reviewed postmyelogram CT studies of the lower lumbar region of 89 patients for radiographic indication of CSF leakage. These patients had outpatient lumbar myelography. We conducted telephone interviews to determine whether a postmyelographic headache occurred. Correlation of CT-verifiable contrast leakage with subsequent development of postmyelogram headache was statistically significant. The early radiographic identification of such patients affords the opportunity for additional measures, such as extended bed confinement, to decrease the morbidity of myelography. Additionally, statistical correlation of such findings should provide an objective method of evaluating the effectiveness of alterations in myelographic technique.

Blood Patch, Epidural↗
PubMed1995

Evaluation of therapeutic drug monitoring of methotrexate in saliva of children with rheumatic diseases.

Pediatric patients with leukemia, other malignancies, and rheumatological disease receive methotrexate chronically. Because of the documented correlation between methotrexate levels of compliance and clinical outcome, it is conceivable to verify appropriate systemic exposure to the drug. Saliva sampling may be of potential interest, especially in children, in whom blood sampling is ethically limited. Our study shows poor correlation between serum total/free methotrexate concentrations and saliva levels, precluding the clinical use of this test.

Adolescent↗
PubMed1995

Protein aggregation kinetics in an Escherichia coli strain overexpressing a Salmonella typhimurium CheY mutant gene.

The tendency of recombinant protein in bacteria to partition into soluble and insoluble forms is attributed, in general, to a kinetic competition between protein folding and aggregation. However, little experimental work has actually been performed in vivo on the kinetics and mechanisms of protein folding and aggregation. Results are presented here from radiolabeling experiments which monitored the kinetics of recombinant protein aggregation in actively growing cultures. The strain used was an Escherichia coli strain overexpressing a Salmonella typhimurium CheY mutant gene. The rate of CheY aggregation was found to be time dependent in that the tendency of CheY to aggregate was greater for newly translated molecules, i.e., those translated within the previous several minutes, than for molecules translated less recently. CheY protein molecules that were translated less recently continued to aggregate for several hours but at a lower rate. The movement of soluble CheY to the insoluble form was enhanced at elevated growth temperatures and inhibited by the presence of chloramphenicol. The latter observation suggests that ongoing translation facilitates the movement of soluble CheY to the insoluble form. The implications of these results for the mechanism of protein aggregation in vivo, i.e., inclusion body formation, are discussed.

Bacterial Proteins↗
PubMed1995

Characterization of a 2,3-dihydroxybiphenyl dioxygenase from the naphthalenesulfonate-degrading bacterium strain BN6.

An extradiol dioxygenase was cloned from the naphthalenesulfonate-degrading bacterial strain BN6 by screening a gene bank for colonies with 2,3-dihydroxybiphenyl dioxygenase activity. DNA sequence analysis of a 1,358-bp fragment revealed an open reading frame of only 486 bp. This is the smallest gene encoding an extradiol dioxygenase found until now. Expression of the gene in a T7 expression vector enabled purification of the enzyme. Gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that the protein was a dimer with a subunit size of 21.7 kDa. The enzyme oxidized 2,3-dihydroxybiphenyl, 3-isopropylcatechol, 3- and 4-chlorocatechol, and 3- and 4-methylcatechol. Since the ability to convert 3-chlorocatechol is an unusual characteristic for an extradiol-cleaving dioxygenase, this reaction was analyzed in more detail. The deduced amino-terminal amino acid sequence differed from the corresponding sequence of the 1,2-dihydroxynaphthalene dioxygenase, which had been determined earlier from the enzyme purified from this strain. This indicates that strain BN6 carries at least two different extradiol dioxygenases.

Amino Acid Sequence↗
PubMed1995

Penile absorption of EMLA cream in piglets: implications for use of EMLA in neonatal circumcision.

EMLA (eutectic mixture of lidocaine and prilocaine) cream is currently not recommended for use in infants < 1 month of age because of the potential risk of methemoglobinemia as a result of the o-toluidine metabolite of prilocaine. We studied bioavailability and changes in methemoglobin levels following topical penile exposure to 1 g of EMLA cream for 1 hour in piglets. Lidocaine, prilocaine, and o-toluidine concentrations were measured simultaneously using a high-performance liquid chromatography method. The systemic bioavailability of EMLA was low: 4.0 +/- (SD) 4.7% for lidocaine (range 0-13.6; n = 8) and 7.2 +/- 5.7% for prilocaine (range 0-14.5; n = 8). The ratio between exposure to o-toluidine with EMLA versus intravenous administration (i.e., AUCEMLA/AUCIV; see text) was also low: 4.2 +/- 9.3% (range 0-28.6; n = 9). The mean maximum methemoglobin value after intravenous administration was 1.23 +/- 0.64% (range 0.5-3.0; n = 12) and after penile application 0.99 +/- 0.36% (range 0.5-2.0; n = 12). The methemoglobin value was elevated significantly above baseline after intravenous administration (p = 0.03), but not after penile application of EMLA. These findings suggest that penile administration of 1 g of EMLA may be safe for neonatal circumcision, but further study is required.

Absorption↗
PubMed1995

Protein binding of acetylsalicylic acid and salicylic acid in porcine and human serum.

As part of a pilot project establishing a porcine model for aspirin overdose, the percentage protein binding of acetylsalicylate (ASA) and salicylate (SA) in porcine and human sera was evaluated in vitro over a range of concentrations. Serum from 2 pigs and 4 humans were spiked with ASA concentrations of 0.5-100 mg/dL and SA concentrations of 1-120 mg/dL. Protein binding for each concentration of ASA and SA was determined using radiolabeled drug and ultrafiltration with the Centrifree micropartition system. The percentage protein binding for ASA in pig and human sera were similarly low (< 50%) for all concentrations evaluated. Percentage protein binding for SA for pig and human sera were high (approximately 90% and 80%) at low therapeutic concentrations, but then declined to approximately 30% at higher toxic concentrations (120 mg/dL). The protein binding of ASA and SA over a range of concentrations was similar for porcine and human sera.

Animals↗
PubMed1995

Comparison of a screening coronal CT versus a contiguous coronal CT for the evaluation of patients with presumptive sinusitis.

BACKGROUND: Computed tomography has greatly improved the accuracy of sinus imaging. While contiguous coronal computed tomography scanning of the sinuses provides detailed imaging as compared with plain sinus radiography, this modality is significantly more expensive and involves exposure of the patient to a higher dose of radiation. It has become increasingly common to obtain screening, or non-contiguous, CT scans of the sinuses when screening for the presence of sinusitis. OBJECTIVE: To calculate the sensitivity and specificity of the screening coronal CT scan of the sinuses in screening for inflammatory disease using the contiguous coronal CT examination of the sinuses as the standard. METHODS: From contiguous coronal computed tomograms of the paranasal sinuses, screening coronal computed tomographic examinations were created for 44 patients. Patients were being screened for the presence of sinusitis in the Comprehensive Sinus Clinic at St. Louis University. The two examinations were reviewed independently and in random order by two neuroradiologists. Using the original examinations as the standard, the sensitivity and specificity of the screening studies were calculated for various situations. RESULTS: Overall, a sensitivity of 93.3% and a specificity of 89.3% for the detection of inflammatory disease of the sinuses by the screening examination was observed. CONCLUSIONS: The screening coronal computed tomogram of the paranasal sinuses may be useful in the evaluation of the patient with possible sinusitis.

Costs and Cost Analysis↗
PubMed1995

Survival after ABO-incompatible allogeneic bone marrow transplant after a preparative regimen of busulfan and cyclophosphamide.

The use of an ABO-incompatible donor for BMT after total body irradiation (TBI) has no adverse effect on engraftment, incidence of GVHD or survival when donor erythrocytes and plasma are depleted from the infused marrow. The outcome of ABO-incompatible BMT following a non-TBI-containing preparative regimen has not been as well studied. We therefore performed a retrospective review of consecutive patients undergoing allogeneic BMT for myeloid leukemia after treatment with high-dose busulfan and cyclophosphamide (BUCY) between January 1984 and January 1993. Of the 199 evaluable patients, 100 had AML or myelodysplastic syndrome, 30 of which were ABO-incompatible, and 99 had CML, 35 of which were ABO-incompatible. All patients undergoing transplant received erythrocyte and plasma-depleted marrow but 14 major ABO-incompatible patients also underwent plasma exchange before transplant. T cell-depletion and purging techniques were not employed. All records were reviewed for prognostic factors including patient age, sex, diagnosis, remission status at the time of transplant, and incidence and severity of acute and chronic GVHD. Compatible and incompatible patients with myeloid leukemia did not differ with respect to age, sex, remission status of disease at the time of transplant or incidence of GVHD.(ABSTRACT TRUNCATED AT 250 WORDS)

ABO Blood-Group System↗
PubMed1995

[What is the prognosis for patients with recurrent gastric carcinoma?].

The authors discuss the problem of relapses of gastric cancer, the conditions of its development and its possible treatment. As a basis they use experience with the treatment of 167 patients operated on account of this condition at the First Surgical Clinic in Olomouc in 1986-1993. In these patients 77 radical operations were performed, 25 developed a relapse of the tumor. Only in two patients it was possible to perform another resection--total gastrectomy. In these two re-resected patients the mean survival period was 9 months, in the remainder only two months. The authors conclude that in relapses of gastric cancer even several months' survival are a success.

Humans↗
PubMed1994

MHC polymorphism and parasites.

The major histocompatibility complex (MHC) polymorphism is marked by the existence of allelic lineages that are extremely old, having been passed from one species to another in an evolutionary line of descent. Each species has several of these lineages and many of their more recent derivatives, the actual alleles. The lineages are separated by large genetic distances and are characterized by the presence of short sequence motifs which, at the protein level, have remained virtually unaltered for over 40 million years. Several explanations for the MHC polymorphism have been proposed. We argue that the only one consistent with the entire body of knowledge about the MHC is an explanation based on the immune response to parasites. Furthermore, we propose that parasites coevolving with their hosts have had a major influence on MHC polymorphism, whereas parasites that switched hosts recently and became very virulent have had little effect. The latter category includes micro- and macroparasites responsible for the major human infectious diseases. This hypothesis explains why no convincing association between human leucocyte antigen (HLA) alleles and resistance to infectious disease can thus far be documented, and indicates the direction in which the search for such associations should be taken.

Animals↗
PubMed1994

Major histocompatibility complex class I genes of the coelacanth Latimeria chalumnae.

The coelacanth fish Latimeria chalumnae is the sole surviving species of a phylogenetic lineage that was founded more than 400 million years ago and that has changed morphologically very little since that time. Little is known about the molecular evolution of this "living fossil," considered by some taxonomists to be the closest living relative of tetrapods. Here we describe the isolation and characterization of L. chalumnae major histocompatibility complex (MHC) class I genes. The exon-intron organization of these genes is the same as that of their mammalian counterparts. The genes fall into four families, which we designate Lach-UA through Lach-UD. There are multiple loci in all of the families. Genes of the first two families are transcribed. The Lach-UA family bears the characteristics of functional, polymorphic class I genes; the other three families may be represented by nonclassical genes. All the Lach loci arose by duplication from an ancestral gene after the foundation of the coelacanth lineage. Intergenic variation is highest at positions corresponding to the mammalian peptide-binding region. The closest relatives of the Lach genes among the MHC genes sequenced thus far are those of the amphibian Xenopus.

Animals↗