A family is reported in which each of two sisters has a son with no detectable hypoxanthine phosphoribosyltransferase (HPRT) (EC 2. 4. 2. 8) in his erythrocytes, a finding considered pathognomonic of ...Lesch-Nyhan disease. However, neither has the stigmata of the disease. One boy is neurologically normal, and the other is moderately retarded. There was only a slight increase in urinary uric acid, but the amounts of hypoxanthine and xanthine, and their ratios, were similar to those found in Lesch-Nyhan disease, strongly indicating that excesses of these last two oxypurines are not responsible for the symptomatology in that disease. In contrast to the nondetectable HPRT activity in the red blood cells, leukocyte lysates from the two boys have 10-15% of normal activity, possibly reflecting continuing synthesis of an unstable enzyme. This hypothesis is supported by the demonstration that at 4°C HPRT activity was rapidly lost in the propositus while the activity increased in control subjects. The mother's cells were intermediate between the two. The intact and disrupted leukocytes of the hemizygote, in the absence of added phosphoribosyl converted as much hypoxanthine to inosinate as the normal cell, and appropriate tests indicated that under these circumstances enzyme concentration is not rate limiting whereas the concentration of the cosubstrate, phosphoribosyl pyrophosphate, is. The capacity for normal function in the intact mutant cell is more representative of in vivo conditions than the lysate, which may explain the important modification of clinical symptomatology, the relatively mild hyperuricosuria, and the presence of mosaicism in the circulating blood cells of the heterozygotes. A similar explanation may apply to other genetic diseases in which incomplete but severe enzyme deficiencies are found in clinically normal individuals.
An associated deficiency in glucose-6-phosphate dehydrogenase in this family permitted confirmation of previous observations on linkage with hypoxanthine phosphoribosyltransferase.
Yip, Lily
C. (University of Cincinnati, Cincinnati, Ohio),
Ramesh Shah, and Richard A. Day
. Metabolic control of penicillinase biosynthesis in
Bacillus cereus
. J. Bacteriol.
88:
297–308. ...1964.—Penicillinase production in strains 5 and 5/B of
Bacillus cereus
in response to treatment by 6-aminopenicillanic acid (APA), penicillin G, (6-
N
-α-(
p
-benzyloxyphenoxy)-propionylamino-penicillanic acid, and cephalosporin C (CC) was found to be analogous to that seen in constitutive strains. Strain 5 did not release penicillinase into the medium to any great extent. Penicillinase production and the effect of the above penicillins on it were found to decline with increasing density of the culture. The penicillins were shown to accelerate or retard the production of penicillinase activity in strain 5 cells during pretreatment at 0 C and during incubation at 37 C. Strains 5 and 5/B gave qualitatively similar responses to penicillin treatment. At 0 C, the specific activity of penicillinase in strain 5 passes through a period of rapid increase at 0 hr and a period of little change at approximately 1 hr, followed by an increased rate of change towards 2 hr. The effect of APA or CC on specific activity of strain 5 cells during treatment at 0 C could not be reversed by one another, but Hg could reverse the increase caused by CC to some extent and the repression caused by APA. The production of penicillinase in the microconstitutive strain 5 of
Bacillus cereus
in response to treatment with CC was influenced by various inhibitors. 8-Azaguanine inhibited the production of the enzyme both during a pretreatment of the cells with CC at 0 C and during the subsequent incubation at 37 C. Actinomycin D, 6-azauracil, 6-thioguanine, and 2-thiocytosine inhibit the increase in penicillinase arising after the pretreatment at 0 C. 6-Azathymine has very little effect on the change of penicillinase activity. The CC-induced change occurring during the 0 C period was postulated to be a process at the level of protein biosynthesis itself; change at 37 C, constituting a delayed response, was considered a process at the level of messenger ribonucleic acid synthesis.
Reduction of 4(5)-nitroimidazole-5(4)-sulfonamide afforded the sulfonamide analogue of 4(5)-aminoimidazole-5(4)-carboxamide (AICA). This was formylated to afford the sulfonamide analogue of ...formyl-AICA and was ring closed to the unsubstituted 6-sulfonyl analogue of guanine, 3-aminoimidazo4,5-e-1,2,4-thiadizine 1,1-dioxide. Diazotiz ation of the latter afforded the corresponding 6-sulfonyl analogue of xanthine. None of the imidazole-sulfonamides or the purine 6-sulfonyl analogues inhibited the growth of L1210 cells in culture nor were they substrates for or significant inhibitors of human hypoxanthine--guanine phosphoribosyltransferase or milk xanthine oxidase.
Intraductal papillary mucinous neoplasms (IPMNs) are non-invasive precursor lesions that can progress to invasive pancreatic cancer and are classified as low-grade or high-grade based on the ...morphology of the neoplastic epithelium. We aimed to compare genetic alterations in low-grade and high-grade regions of the same IPMN in order to identify molecular alterations underlying neoplastic progression.
We performed multiregion whole exome sequencing on tissue samples from 17 IPMNs with both low-grade and high-grade dysplasia (76 IPMN regions, including 49 from low-grade dysplasia and 27 from high-grade dysplasia). We reconstructed the phylogeny for each case, and we assessed mutations in a novel driver gene in an independent cohort of 63 IPMN cyst fluid samples.
Our multiregion whole exome sequencing identified
, a previously unreported genetic driver of IPMN tumorigenesis, with hotspot mutations in one of two codons identified in >50% of the analyzed IPMNs. Mutations in
were significantly more prevalent in low-grade regions in our sequenced cases. Phylogenetic analyses of whole exome sequencing data demonstrated diverse patterns of IPMN initiation and progression. Hotspot mutations in
were also identified in an independent cohort of IPMN cyst fluid samples, again with a significantly higher prevalence in low-grade IPMNs.
Hotspot mutations in
occur at high prevalence in IPMNs. Unique among pancreatic driver genes,
mutations are enriched in low-grade IPMNs. These data highlight distinct molecular features of low-grade and high-grade dysplasia and suggest diverse pathways to high-grade dysplasia via the IPMN pathway.
Microbes in the built environment have been implicated as a source of infectious diseases. Bacterial culture is the standard method for assessing the risk of exposure to pathogens in urban ...environments, but this method only accounts for <1% of the diversity of bacteria. Recently, full-length 16S rRNA gene analysis using nanopore sequencing has been applied for microbial evaluations, resulting in a rise in the development of long-read taxonomic tools for species-level classification. Regarding their comparative performance, there is, however, a lack of information.
Here, we aim to analyze the concordance of the microbial community in the urban environment inferred by multiple taxonomic classifiers, including ARGpore2, Emu, Kraken2/Bracken and NanoCLUST, using our 16S-nanopore dataset generated by MegaBLAST, as well as assess their abilities to identify culturable species based on the conventional culture results.
According to our results, NanoCLUST was preferred for 16S microbial profiling because it had a high concordance of dominant species and a similar microbial profile to MegaBLAST, whereas Kraken2/Bracken, which had similar clustering results as NanoCLUST, was also desirable. Second, for culturable species identification, Emu with the highest accuracy (81.2%) and F1 score (29%) for the detection of culturable species was suggested.
In addition to generating datasets in complex communities for future benchmarking studies, our comprehensive evaluation of the taxonomic classifiers offers recommendations for ongoing microbial community research, particularly for complex communities using nanopore 16S rRNA sequencing.
The prolonged incubation period of traditional culture methods leads to a delay in diagnosing invasive infections. Nanopore 16S rRNA gene sequencing (Nanopore 16S) offers a potential rapid diagnostic ...approach for directly identifying bacteria in infected body fluids. To evaluate the clinical utility of Nanopore 16S, we conducted a study involving the collection and sequencing of 128 monomicrobial samples, 65 polymicrobial samples, and 20 culture-negative body fluids. To minimize classification bias, taxonomic classification was performed using 3 analysis pipelines: Epi2me, Emu, and NanoCLUST. The result was compared to the culture references. The limit of detection of Nanopore 16S was also determined using simulated bacteremic blood samples. Among the three classifiers, Emu demonstrated the highest concordance with the culture results. It correctly identified the taxon of 125 (97.7%) of the 128 monomicrobial samples, compared to 109 (85.2%) for Epi2me and 102 (79.7%) for NanoCLUST. For the 230 cultured species in the 65 polymicrobial samples, Emu correctly identified 188 (81.7%) cultured species, compared to 174 (75.7%) for Epi2me and 125 (54.3%) for NanoCLUST. Through ROC analysis on the monomicrobial samples, we determined a threshold of relative abundance at 0.058 for distinguishing potential pathogens from background in Nanopore 16S. Applying this threshold resulted in the identification of 107 (83.6%), 117 (91.4%), and 114 (91.2%) correctly detected samples for Epi2me, Emu, and NanoCLUST, respectively, in the monomicrobial samples. Nanopore 16S coupled with Epi2me could provide preliminary results within 6 h. However, the ROC analysis of polymicrobial samples exhibited a random-like performance, making it difficult to establish a threshold. The overall limit of detection for Nanopore 16S was found to be about 90 CFU/ml.
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