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Biomedical subjects

J M Becker

Publications and source records attributed to J M Becker.

At least 235 records · Page 13Linked to original sources
PubMed1979

Leukocyte counts and arterial blood gases in nonrenal psoriatic patients treated with extracorporeal devices: Preliminary report.

Four psoriatic patients with normal renal function were treated with RP-6 dialyzers. There was a significant decrease in the leukocyte counts at 5 mins of hemofiltration and it remained the same without rebound leukocytosis at 60 mins. Leukopenia was not accompanied by changes in PaO2 or PaCO2 and thus not accompanied by hypoxemia. C3 values were also unchanged, although a tendency to decrease was noted. Leukopenia and hypoxemia may not be related.

Blood Gas Analysis↗
PubMed1979

Bis(2-ethylhexyl) phthalate levels in nonuremic patients treated with extracorporeal devices.

DEHP levels after treatment were studied in 6 nonuremic psoriatic patients undergoing extracorporeal therapy. Serum DEHP levels at the end of therapy of these patients were significantly lower than that of maintenance hemodialysis patients. DEHP and/or its metabolites were excreted by the normal kidneys, although the excretion of nonmetabolized DEHP by the kidneys was minimal. There was no correlation between serum DEHP levels of these nonuremic patients and the type of artificial kidney used or the mode of therapy employed.

Blood↗
PubMed1978

Endocrine tests in phenotypic children with bilateral impalpable testes can reliably predict "congenital" anorchism.

Congenital anorchism is a rare condition. Bilateral impa-pable undescended testes are relatively common by comparison. Surgical exploration has been regarded as the final arbiter between anorchism and bilateral cryptorchism. Exploration has not proved completely reliable in making this differentiation. Endocrine studies, particularly the human chorionic gonadotropin (HCG) stimulation test together with measurements of basal plasma gonadotropins, can reliably exclude "functioning" testicular tissue. Eleven fully evaluated and operated cases support this contention. In the specific clinical setting of a normal phenotypic male child with a 46XY karyotype and no müllerian structures palpable on rectal examination, nonfunctioning testes on endocrine testing means congenital anorchism and surgical confirmation is unnecessary. In contradistinction, a positive HCG test would appear to mandate through and extensive surgical exploration.

Child↗
PubMed1978

Low molecular weight dextran and reexploration in the management of ischemic midgut-volvulus.

Administration of low molecular weight dextran and reexploration in 36-48 hr, is recommended in cases of ischemic midgut volvulus. Five cases are presented utilizing this technique and many centimeters of small bowel were saved that would have been resected at time of the original exploration. One patient died as a result of sepsis due to central intravenous nutrition: the others are alive and well.

Dextrans↗
PubMed1978

Peptide utilization in Pseudomonas aeruginosa: evidence for membrane-associated peptidase.

A methionine auxotroph of Pseudomonas aeruginosa grew on methionine-containing peptides as a source of the required amino acid. Amino-terminus-blocked peptides would not serve as growth substrates, despite the fact that peptidases active on these blocked peptides were readily detectable in cell extracts. No evidence was found for extracellular enzymes capable of degrading the oligopeptides investigated. The degradative enzymes were not found in the periplasmic space of the cellular envelope. A high proportion of cellular peptidase activity was associated with the particulate (membrane) fraction of the cell lysate.

Bacteriolysis↗
PubMed1978

Isolation of a peptide transport-deficient mutant of yeast.

A peptide transport mutant of a leucine-lysine auxotroph of Saccharomyces cerevisiae (strain Z1-2D) was isolated on the basis of its resistance to L-ethionyl-L-alanine. The mutant, designated Z1-2D Etar, did not utilize di- and tripeptides containing leucine or lysine although it contained peptidases which released the required amino acids from these substrates. S. cerevisiae Z1-2D Etar did not accumulate radioactivity from [14C]glycyl-L-leucine under conditions identical to those in which the parent took up the label from this dipeptide. These results indicate that the mutant lacks the cellular mechanism to transport peptides to the site of the peptidase activity and that di- and tripeptides share a common mode of entry into yeast.

Biological Transport↗
PubMed1978

Segmental colonic gangrene: a surgical emergency in the hemolytic-uremic syndrome.

A 2 1/2-year-old girl had rectal bleeding, an abdominal mass, and diffuse peritonitis. A segment of gangrenous colon was removed. Following surgery she developed the hemolytic-uremic syndrome (HUS), which is characterized by renal failure, hemolytic anemia, and the thrombocytopenia. The intestinal manifestations associated with the HUS are stressed. This case demonstrates that gangrenous bowel can occur in these patients, and that their survival may depend on resectional surgery.

Child, Preschool↗
PubMed1977

Transport of [14C]Gly-Pro in a proline peptidase mutant of Salmonella typhimurium.

The transport of [14C]Gly-Pro was examined using a mutant of Salmonella typhimurium (strain TN87) deficient in an X-Pro dipeptidase and an X-Pro-Y iminopeptidase. The dipeptide was taken up by one saturable transport system having a Km of 5.3-10(-7)M and a V of 1.4 nmol/mg dry wt cell per min. The uptake of Gly-Pro was not inhibited by amino acids or tripeptides and the transport system exhibited a rather broad side chain specificity for dipeptides. Dipeptides containing hydrophobic residues were the most potent inhibitors of this dipeptide transport system exhibiting Ki values between 10(-8) and 10(-7) M. In contrast, dipeptides containing glycine residues were particularly weak inhibitors. Finally, Gly-Pro was found to be in the intact form inside the cell and was concentrated more than 1000-fold.

Amino Acids↗
PubMed1977

A biologic and genetic study of 40 cases of severe pure mental retardation.

The family history of 40 patients with severe "pure" mental retardation (MR) was studied to determine the incidence of mental retardation and dull-normal intelligence among relatives, probable etiologies and an empiric recurrence risk. Significant findings include: (1) an increased sex ratio (69% males) of propositi, (2) a significant proportion of patients with clinical manifestations besides MR, (3) virtually no consanguinity among parents, (4) a "positive" family history for over 1/2 of the propositi--about 37% of all children in the sibships were affected; about 21% of the full sibs were affected, (5) a higher number of offspring produced by dull persons and a lower number of offspring from retarded persons compared to two normal persons (6) a proportionately large number of affected children produced from matings involving one or two dull persons, (7) a tendency for dull to have additional dull children and mentally retarded parents to have further retarded children while normal parents with more than one affected child usually had further retarded children, (8) an incidence of affected parents of about 32%, and (9) an overall empiric recurrence risk of 14%. Several etiologies were discussed as possible causes of the condition(s) in this group: (unrecongized) environmental damage and/or maternal/fetal interaction; unrecognized chromosome abnormalities; the homozygous state of several different autosomal recessive gees: X-linked recessive mutations; autosomal dominat new mutations; and mutifactoral inheritance. It was concluded that the group was etiologically heterogeneous and although none of the probable etiologies could be excluded, it seemed reasonable to assume that autosomal recessive inheritance plays an important role in the etiology of severe "pure" mental retardation.

Adolescent↗
PubMed1977

Peptide transport in yeast: utilization of leucine- and lysine-containing peptides by Saccharomyces cerevisiae.

A variety of leucine-containing di- and tripeptides and two lysine-containing dipeptides supported the growth of strain Z1-2D, a leucine, lysine auxotroph of Saccharomyces cerevisiae. However, (Lys)2, (Lys)3, (Lys)4, and (Lys)5 as well as Gly-Leu-Gly, three tetra- and one pentapeptide containing leucine were not utilized by the mutant. Cellular peptidases released leucine or lysine from all of these non-growth-supporting peptides, suggesting that the failure of strain Z1-2D to utilize these compounds reflects their failure to enter the yeast. Competition studies employing phenylalanine or non-leucine-containing peptides showed that the uptake of peptides into S. cerevisiae Z1-2D is distinct from that of amino acids and that di- and oligopeptides may share a common transport system. The failure of strain Z1-2D to utilize any peptide larger than (Leu)3 may indicate a transport size limit. Such a size limit would influence the construction of models that explain the action of yeast mating factors.

Biological Transport, Active↗
PubMed1977

Nonoperative management of splenic trauma in children: a report of six consecutive cases.

Postsplenectomy sepsis, although infrequent, is real and hazardous. We have taken a nonoperative approach to the child with a ruptured spleen who is in stable condition. Six consecutive patients with a diagnosis confirmed by angiography or scan were treated without surgery. The results suggest the usefulness of this approach in the child who is not bleeding massively.

Blood Transfusion↗
PubMed1976

Oligopeptide transport in proline peptidase mutants of Salmonella typhimurium.

Investigations of peptide transport in Salmonella typhimurium are presented. A strain designated proB25, a proline auxotroph, grew on a variety of di, tri-, and tetrapeptides containing proline. In contrast (Pro)6, peptides acylated on the NH2 terminus and Ala-Pro-D-Ala did not satisfy the nutritional requirement of proB25 for proline because they were not transported. A derivative of proB25, strain TN87, deficient in a proline aminopeptidase and an X-Pro dipeptidase, was able to utilize only four of 25 proline-containing peptides investigated. The inability of TN87 to grow on most of these peptides was due to the lack of the requisite peptidase activity. Evidence for a functional dipeptide transport system in this strain is indicated by growth on Pro-Leu and Pro-Ala, and by growth inhibition by certain X-Pro dipeptides. Leu-Pro, Val-Pro, Met-Pro, and Arg-Pro cause temporary growth inhibition of strain TN87 whereas Gly-Pro, Ala-Pro, and Pro-Pro have no effect on growth. Evidence for a functional oligopeptide transport system is indicated by growth on Pro-Val-Gly and Pro-Gly-Gly and by uptake of label from L-methionyl-L-methionyl-L-[14C]methionine and L-alanyl-L-prolyl-[14C]glycine. The presence of multiple oligopeptide transport systems for certain proline-containing peptides was demonstrated using triornithine-resistant mutants (oligopeptide permease deficient) and competition experiments. Finally L-Ala-L-Pro-[14C]Gly is shown to be transported intact into strain TN87.

Acyltransferases↗
PubMed1976

Basis for the design of anticandidal agents from studies of peptide utilization in Canadida albicans.

The growth of Candida albicans WD 18-4, a methionine and lysine double auxotroph, on a variety of methionine- and lysine-containing peptides was determined. This yeast does not excrete extracellular peptidases. Thus, the growth response to peptides containing the required amino acid is a measure of peptide transport. A variety of methionine-containing peptides such as Met-Met, Met-Met-Met, and Met-Met-Met-Met-Met are transported. Acylation of the N-terminus of transported peptides does not affect their transport, but derivitization of the C-terminus prevents peptide uptake. In contrast, all lysine-containing peptides tested, except Lys-Gly, were not growth substrates. The inability of a peptide to substitute for the requisite amino acid was not due to the absence of cellular peptidases or to toxicity of the nonutilized peptides. Several potentially toxic amino acids were carried into Candida as a component of transported peptides. This establishes the peptide transport system as a possible tool for the design of antibiotics for Candida albicans.

Antifungal Agents↗
PubMed1975

Multiplicity of oligopeptide transport systems in Escherichia coli.

The ability of Escherichia coli K-12 4212 to utilize a variety of oligopeptides as sources of required amino acids was examined. Triornithine-resistant mutants of this strain were oligopeptide permease deficient (Opp-) as judged by their inability to utilize (Lys)3 and (Lys)4 as sources of lysine and their resistance to the toxic tripeptide (Val)3. These same mutants were able to grow when Met-Met-Met, Met-Gly-Met, Met-Gly-Gly, Gly-Met-Gly, Gly-Gly-Met, Gly-Met-Met, Met-Met-Gly, or Leu-Leu-Leu were supplied in place of the requisite amino acid. The system mediating the uptake of these peptides, herein designated Opr I, was not able to transport N-alpha-acetylated peptides, nor the tetrapeptides Met-Gly-Met-Met, Met-Met-Gly-Met, or Met-Met-Met-Gly. Competition experiments indicated that trimethionine and trileucine enter E. coli K-12 via either Opp or Opr I. Analogous results were found using the methionine, leucine-requiring auxotroph E. coli B163. It appears that more than one oligopeptide transport system exists in E. coli and that the system mediating peptide uptake is complex.

Biological Transport, Active↗