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Selective attention deficits in poor readers? Dichotic listening, speeded classification, and auditory and visual central and incidental learning tasks.

Poor readers (PRs) and controls (i.e., normal readers) from the second, fourth, and sixth grades were compared on four tasks chosen to measure the development of selective attention. The PRs performed more poorly than controls on the central but not on the incidental portion of an auditory memory task. The differences on the central task were interpreted as a function of group differences in mnemonic skills rather than selective attention. There were no group differences on either central or incidental portions of a visual memory task. In a speeded classification task, PRs exhibited a slower rate of information processing, measured in bits of information transmitted per second, than controls, but this difference in rate was not affected by distraction. On a dichotic listening task, PRs performed more poorly than controls under a variety of conditions in which the presence of distraction, the rate of information presentation, and attended ear were manipulated; the pattern of differences obtained, however, was not readily interpretable as a function of greater distractibility on the part of PRs than controls. As a whole, the results did not support the hypothesis that PRs show deficits in selective attention relative to age-matched normal readers. In addition, correlations computed among indices of selectivity (residualized gain scores) derived from the four tasks were uniformly low, suggesting that the four tasks did not measure the same cognitive construct. The implications for the study of reading disabilities and for the construct of selective attention in developmental studies are discussed.

Attention↗

[A randomized controlled study on vindesine and vincristine in combination with prednisolone in the treatment of adult acute lymphocytic leukemia and blastic crisis of chronic myeloid leukemia].

Sixty patients with adult acute lymphocytic leukemia (ALL) and 40 patients with blastic crisis of chronic myeloid leukemia (CML . BC) were randomly allocated by envelope method to receive either vindesine (VDS; 2 mg/m2 i.v., twice or once weekly) or vincristine (VCR; 1.2 mg/m2 i.v., once weekly) in combination with prednisolone (Pred; 40 mg/m2 p.o., daily). Out of 100 patients entered, 53 patients with ALL and 34 patients with CML . BC were evaluable. Remissions for ALL were seen in 20 of 25 patients (80.0%; 12 CRs and 8 PRs) treated with VDS regimen, and in 17 of 28 patients (60.7%; 7 CRs and 10 PRs) treated with VCR regimen, respectively. For CML . BC, however, remission rates for VDS regimen (42.1%; 5 CRs and 3 PRs in 19 patients) and for VCR regimen (40.0%; 2 CRs and 4 PRs in 15 patients) were equivalent. Overall remission rates of VDS regimen for both diseases, twice weekly regimen (65.5%; 11 CRs and 8 PRs in 29 patients) and once weekly regimen (60.0%; 6 CRs and 3 PRs in 15 patients) were similar. Patients treated with either regimen experienced high incidence of neurotoxicity. Neurotoxic disturbance appeared severer in patients treated with VCR regimen. Incidence of leukopenia and alopecia was high in patients treated with VDS regimen. These data suggest that VDS in combination with Pred is comparable-rather superior-to VCR in combination with Pred for adult ALL and CML . BC. Less neurotoxic and sufficiently effective dosage of VDS is considered to be 2 mg/m2, once weekly.

Adult↗

Ventricular function during liver reperfusion in hepatic transplantation. A transesophageal echocardiographic study.

Postreperfusion syndrome (PRS) is the most dramatic and acute hemodynamic alteration that occurs in OLT. Our aim was to determine heart function by hemodynamic monitoring and transesophageal echocardiography during PRS. We studied 24 nonconsecutive patients allocated to 2 groups: group A (n = 8), patients with PRS, and group B (n = 16), patients without PRS. Usual hemodynamic data were obtained simultaneously with transesophageal echocardiography recording of the left ventricular imaging in 4 different stages: after induction of anesthesia, 5 min before the end of the anhepatic phase, between 2 and 5 min after reperfusion, and 5 min after graft reperfusion. The hemodynamic and echocardiographic findings during reperfusion were (group A vs. group B patients): mean arterial pressure, 50.0 +/- 15.2 vs. 74.7 +/- 13.9 mmHg (P < 0.01); pulmonary capillary wedge pressure, 12.7 +/- 6.1 vs. 13.9 +/- 5.7 mmHg (NS); left ventricular ejection fraction, 79.6 +/- 9.3 vs. 83.4 +/- 9.4% (NS); left ventricular end diastolic volume index, 35.5 +/- 12.7 vs. 54.7 +/- 21.3 ml/m2 (P < 0.05); and stroke volume index, 27.9 +/- 8.9 vs. 45.5 +/- 15.9 ml/m2 (P < 0.01). There was a mild decrease in left ventricular compliance in group A. We found no alteration in left ventricular function that can justify PRS. The hemodynamic changes during PRS seemed to be caused by an insufficient increase in preload after unclamping.

Diastole↗

Mutation of the p53 gene in postradiation sarcoma.

Radiotherapy is known to cause secondary malignancies in the radiation field; postradiation sarcomas (PRS) are one example of such malignancies. Little is known about the genetic changes, including p53 gene alterations, that are thought to play a role in the tumorigenesis of human PRS. In the present study, p53 gene mutations were analyzed on paraffin-embedded specimens from 24 patients with PRS (4 men and 20 women) by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) followed by direct sequencing. The primary tumors of these patients were uterine cervical cancers in 14, breast cancers in 3, malignant lymphomas in 2, and others in 5. Total radiation doses ranged from 36 to 300 Gy (median, 60 Gy). The latent period between completion of radiation therapy and development of PRS ranged from 3 to 34 years (median, 10 years). Malignant fibrous histiocytoma was the most common PRS, accounting for 12 cases. PCR-SSCP revealed the aberrant mobility shifts of bands in 24 cases: 21 shifts in exon 5, 18 in exon 7, and 12 in exon 8. Direct sequencing of the SSCP product revealed a total of 58 mutations in 21 (88%) of 24 cases: 4 cases had a single mutation, 5 had 2 mutations, 5 had 3 mutations, 6 had 4 mutations, and 1 had 5 mutations. Although 31% of the mutations did not change an amino acid, every tumor had at least one mutation that did, which may have provided the selection pressure for expansion. The frequency of p53 gene mutation in sporadic soft tissue sarcomas was 20%. These findings highlighted the extraordinarily high frequency of p53 gene mutations in PRS. G:C to A:T transition at dipyrimidine sites was found in 14 (58%) of 24 cases. Collectively, these findings indicate that radiation is causative for soft tissue sarcomas via p53 gene mutations.

Adolescent↗

Development and pilot testing of a prostate cancer polygenic risk report.

BACKGROUND: Polygenic risk scores (PRS) are increasingly being incorporated into clinical care, yet optimal strategies for communicating PRS results to patients and clinicians remain undefined. Effective report design is critical to ensure comprehension and appropriate use, particularly for complex conditions such as prostate cancer where screening decisions are nuanced. We developed and pilot tested patient-facing materials to communicate integrated polygenic and monogenic risk for prostate cancer in the context of a randomized clinical trial. METHODS: We designed a summary report and accompanying Frequently Asked Questions (FAQ) page to communicate prostate cancer genetic risk within the Prostate Cancer, Genetic Risk, and Equitable Screening Study (ProGRESS). Materials were developed through an iterative, multidisciplinary process informed by existing literature on genomic risk communication. We conducted semi-structured interviews with a national sample of eight men eligible for prostate cancer screening to evaluate comprehension, interpretation of visual elements, perceived usefulness, and preferences for improvement. Interviews were transcribed and analyzed using reflexive thematic analysis. RESULTS: Participants generally found the summary report and FAQ page understandable and visually engaging. Graphical displays of absolute risk, particularly pictograph arrays, facilitated comprehension and helped contextualize risk. Visual cues such as color and bold formatting effectively directed attention to key information, with red coloring perceived as particularly salient for high-risk results. In contrast, more complex visualizations, including bell curves and incidence curves, were frequently misunderstood or not interpreted as intended. Participants expressed a desire for clearer guidance regarding next steps and additional accessible information, suggesting supplementary resources such as hyperlinks or QR codes. Concerns about readability included small font size and high text density. CONCLUSIONS: In this qualitative pilot study, patient-facing materials for communicating prostate cancer PRS were generally well received, with specific design features such as simple visualizations and clear formatting enhancing understanding. Findings highlight the importance of intuitive risk displays and actionable guidance in PRS reporting. These results provide practical insights to inform the design of genomic risk reports as PRS-based prostate cancer screening approaches move toward clinical implementation. TRIAL REGISTRATION: ClinicalTrials.gov NCT05926102; date of registry: July 3, 2023.

Aged↗

Suspended circummandibular wire fixation for mixed-dentition pediatric mandible fractures.

OBJECTIVE: To introduce and evaluate the technique of cirummandibular wires with piriform rim suspension (CMW-PRS) combined with arch bars and a fracture site bridle in the treatment of mixed-dentition pediatric mandible fractures. DESIGN: Five male patients (mean age, 8.2 years [age range, 7-10 years]) with an isolated mixed-dentition mandible fracture were treated with the CMW-PRS technique at the University of Texas Health Science Center, San Antonio, from 1985 to 1987 and at the University of Missouri, Columbia, from 1992 to 1995. Clinical and radiographic fracture healing, somatosensory status, and complications were evaluated. RESULTS: All patients demonstrated clinical union to their preinjury occlusion by 3 or 4 weeks. They remained without complications until they were no longer available for follow-up. Panoramic radiographs supported the findings of clinical examinations throughout the study, and no radiographic abnormalities were found. There were no somatosensory disturbances of the lingual or mental/inferior alveolar nerves. One patient required a tracheostomy unrelated to the procedure. CONCLUSION: The CMW-PRS technique combined with arch bars and a fracture site bridle wire achieved equivalent historical results when compared with the dental splint. The potential advantages and disadvantages of the CMW-PRS technique compared with those of monocortical bone plating, as well as the significant advantages of the CMW-PRS over the dental splint, are discussed in the text.

Bone Wires↗

Structural studies of FIV and HIV-1 proteases complexed with an efficient inhibitor of FIV protease.

Three forms of feline immunodeficiency virus protease (FIV PR), the wild type (wt) and two single point mutants, V59I and Q99V, as well as human immunodeficiency virus type 1 protease (HIV-1 PR), were cocrystallized with the C2-symmetric inhibitor, TL-3. The mutants of FIV PR were designed to replace residues involved in enzyme-ligand interactions by the corresponding HIV-1 PR residues at the structurally equivalent position. TL-3 shows decreased (improved) inhibition constants with these FIV PR mutants relative to wt FIV PR. Despite similar modes of binding of the inhibitor to all PRs (from P3 to P3'), small differences are evident in the conformation of the Phe side chains of TL-3 at the P1 and P1' positions in the complexes with the mutated FIV PRs. The differences mimick the observed binding of TL-3 in HIV-1 PR and correlate with a significant improvement in the inhibition constants of TL-3 with the two mutant FIV PRs. Large differences between the HIV-1 and FIV PR complexes are evident in the binding modes of the carboxybenzyl groups of TL-3 at P4 and P4'. In HIV-1 PR:TL-3, these groups bind over the flap region, whereas in the FIV PR complexes, the rings are located along the major axis of the active site. A significant difference in the location of the flaps in this region of the HIV-1 and FIV PRs correlates with the observed conformational changes in the binding mode of the peptidomimetic inhibitor at the P4 and P4' positions. These findings provide a structural explanation of the observed Ki values for TL-3 with the different PRs and will further assist in the development of improved inhibitors.

Animals↗

Recombination and amplification of pyrimidine-rich sequences may be responsible for initiation and progression of the Xq27 fragile site: an hypothesis.

HYPOTHESIS: A pyrimidine-rich sequence (PRS) of DNA is present as a normal sequence in the q27 band of the human X chromosome. Under conditions of pyrimidine nucleotide triphosphate deprivation during S phase, deoxyuridine monophosphate is misincorporated and has to be excised during G2 by DNA repair mechanisms. When a simple PRS is present on both homologous X chromosomes during oogenesis, PRS may undergo amplification through non-homologous crossing-over to produce the initial lesion of the fragile (X). Carriers of such initial lesions will be unaffected transmitting females or males. When an X chromosome bearing such an initial lesion is itself paired with a homologous X carrying a simple PRS during oogenesis, a much higher rate of non-homologous crossing-over may occur resulting in progression to an even longer stretch of pyrimidine rich DNA in this region; the increased length of PRS through amplification makes the region too long to be repaired during G2 and allows it to be seen as a fragile site in metaphase chromosome preparations. Furthermore, this amplified lesion may interfere with transcription of one or more genes in this region and produce the phenotype of the Martin-Bell syndrome.

Base Sequence↗

Outcome after local recurrence of osteosarcoma: the St. Jude Children's Research Hospital experience (1970-2000).

BACKGROUND: Despite improvements in therapy for osteosarcoma, approximately 4-10% of patients experience a local recurrence and have a poor prognosis. METHODS: The authors analyzed prognostic factors for survival in 26 patients with a local recurrence of osteosarcoma who were treated between 1970 and 2000. RESULTS: The initial surgical procedure was amputation in 20 patients (76.9%) and limb salvage in 6 patients (23.1%). The median time from the diagnosis of osteosarcoma to local recurrence was 1.2 years (range, 1.2 months-6.1 years). Eleven patients (42.3%) developed an isolated local recurrence and 15 patients (57.7%) developed local and distant recurrence. The 5-year estimate of postrecurrence survival (PRS) (+/- 1 standard error) for the 26 patients was 19.2% +/- 7.7%. Recurrence > or = 2 years from the time of diagnosis was found to predict a better outcome (5-year PRS of 50.0% +/- 20.4%) compared with earlier recurrence (10.0% +/- 5.5%) (P = 0.037). Patients with negative margins after initial surgery were found to have improved survival (5-year PRS of 33.3% +/- 13.6%) compared with patients with positive margins (7.1% +/- 4.9%) (P = 0.015). Patients who underwent complete surgical resection at the time of recurrence were found to have a better PRS (5-year PRS of 41.7% +/- 14.2%) compared with patients who did not undergo surgery (0% +/- 0%) (P < 0.001). CONCLUSIONS: The prognosis for patients after local recurrence of osteosarcoma is poor. Complete surgical resection at the time of recurrence is essential for survival. Positive margins at the time of initial surgical resection and early recurrence appear to be poor prognostic factors.

Adolescent↗

Toward a universal inhibitor of retroviral proteases: comparative analysis of the interactions of LP-130 complexed with proteases from HIV-1, FIV, and EIAV.

One of the major problems encountered in antiviral therapy against AIDS is the emergence of viral variants that exhibit drug resistance. The sequences of proteases (PRs) from related retroviruses sometimes include, at structurally equivalent positions, amino acids identical to those found in drug-resistant forms of HIV-1 PR. The statine-based inhibitor LP-130 was found to be a universal, nanomolar-range inhibitor against all tested retroviral PRs. We solved the crystal structures of LP-130 in complex with retroviral PRs from HIV-1, feline immunodeficiency virus, and equine infectious anemia virus and compared the structures to determine the differences in the interactions between the inhibitor and the active-site residues of the enzymes. This comparison shows an extraordinary similarity in the binding modes of the inhibitor molecules. The only exceptions are the different conformations of naphthylalanine side chains at the P3/P3' positions, which might be responsible for the variation in the Ki values. These findings indicate that successful inhibition of different retroviral PRs by LP-130 is achieved because this compound can be accommodated without serious conformational differences, despite the variations in the type of residues forming the active-site region. Although strong, specific interactions between the ligand and the enzyme might improve the potency of the inhibitor, the absence of such interactions seems to favor the universality of the compound. Hence, the ability of potential anti-AIDS drugs to inhibit multiple retroviral PRs might indicate their likelihood of not eliciting drug resistance. These studies may also contribute to the development of a small-animal model for preclinical testing of antiviral compounds.

Antiviral Agents↗

Isolation of phosphoribosylpyrophosphate synthetase (PRS1) gene from Candida albicans.

We have isolated a 3.7 kb EcoR1 fragment from a genomic library of Candida albicans which displayed a 65% level of identity with the PRS gene family (PRS) of Saccharomyces cerevisiae. The PRS gene encodes a phosphoribosylpyrophosphate (PRPP) synthetase of S. cerevisiae, which catalyses the synthesis of purines, pyrimidines, and amino acids such as histidine and tryptophan. By Northern analyses, we observed that the entire 3.7 kb EcoR1 fragment as well as 1.1 kb KpnI-SacI internal fragment of the 3.7 kb EcoR1 fragment hybridized to the same 1.4 kb transcript. An internal 2.6 kb KpnI fragment was subcloned and sequenced. A deduced sequence of 321 amino acids representing a polypeptide of 35.2 kDa was determined. A FASTA search indicated that the C. albicans PRS (Ca PRS1) had an overall homology at the amino acid level of 91% with the S. cerevisiae PRS3. Putative transcriptional start and termination sequences as well as a cation-binding, PRPP synthetase signature sequence were identified. Ca PRS1 was localized to chromosome 2 of the C. albicans genome. Low stringency hybridizations indicates that the organism may possess multiple PRS genes. The function of these genes in nitrogen signaling is discussed.

Amino Acid Sequence↗

Progesterone receptors as neuroendocrine integrators.

Intracellular progesterone receptors (PRs) are ligand-inducible transcription factors that mediate the majority of the effects of progesterone (P) on neuroendocrine functions. During the past decade, evidence has accumulated which suggest that PRs can also be activated independently of P, by signals propagated through membrane-bound receptors to the interior of cells. The activation of PRs by this type of "cross-talk" mechanism has been implicated in the physiological regulation of several important neuroendocrine processes, including estrous behavior and periovulatory hormone secretions. We review evidence that both ligand-dependent and ligand-independent activation of PRs occurs in central neurons and in anterior pituitary cells and that the convergence and summation of these signals at the PR serves to integrate neural and endocrine signals which direct several critically important neuroendocrine processes. An integrative function for PRs is reviewed in several physiological contexts, including the display of lordosis behavior in female rodents, the neurosecretion of gonadotropin-releasing hormone surges, secretion of preovulatory gonadotropin surges, and release of periovulatory follicle stimulating hormone surges. The weight of evidence indicates that cross talk at the intracellular PR is an essential component of the integrative mechanisms that direct each of these neuroendocrine events. The recurrence of PR's integrative actions in several different physiological contexts suggests that other intracellular steroid receptors similarly function as integrators of neural and endocrine signals in other neuroendocrine processes.

Animals↗

Proteolytic processing of foamy virus Gag and Pol proteins.

The foamy viral proteases (FV PRs) are set apart from other retroviral processing enzymes by unique features. The first remarkable property is that FV PRs are enzymatically active as high-molecular-mass Pro-Pol proteins. Hence there exist multiple forms of active FV PRs that likely contribute to cleavage site specificity. A FV PR of low molecular size is not detectable in purified virions, in contrast to PRs of other retroviruses that are found in virus particles. Because the major part of Pol remains attached to the amino-terminal enzymatically active PR protein region, the FV-specific way of expressing Pro-Pol polyproteins from a pol-specific transcript provides for the incorporation of Pro-Pol and IN into virus particles. Proteolytic processing of Gag and Pol proteins is incomplete and delayed. Another novel feature is that the catalytic center of the active dimers of cat FV PR consists of D-S/T-Q instead of D-S/T-G, an unprecedented feature of this enzyme. The temporal and spatial control and the factors that regulate FV PRs remain to be elucidated.

Amino Acid Sequence↗

Localization of human phosphoribosylpyrophosphate synthetase subunit I and II genes (PRPS1 and PRPS2) to different regions of the X chromosome and assignment of two PRPS1-related genes to autosomes.

Complementary DNA clones for phosphoribosylpyrophosphate synthetase subunits I and II (PRS I and PRS II) were used to determine the chromosomal localization of the corresponding human genes. Southern blot analysis of genomic DNAs isolated from human placenta and a panel of human-mouse somatic cell hybrids revealed that the rat PRS I cDNA probe detected at least five human specific DNA segments (23, 20, 14.5, 6.7, and 4.3 kb) in BamHI digests. The 23-, 14.5-, and 6.7-kb DNA segments were detected only if the hybrids contained human chromosome X or translocation chromosome 7p+ (7qter greater than 7p22::Xq21 greater than Xqter), indicating the location of these segments to Xq21-qter (PRPS1). The 20- and 4.3-kb DNA segments did not cosegregate with the other three segments, and spot blot hybridization analysis using flow-sorted human chromosomes indicated that these are the PRPS1-related genes (PRPS1L1 and PRPS1L2) and could be assigned to chromosomes 7 and 9, respectively. The human-specific PRS II cDNA probe revealed a BamHI DNA segment (17 kb), which segregated condordantly with the X chromosome but not with the PRPS1 gene. We surmise that the gene for PRS II (PRPS2) is located at a different region of the X chromosome, namely Xpter-a21.

Animals↗

Prevalence of primitive reflexes and the relationship with cognitive change in healthy adults: a report from the Maastricht Aging Study.

OBJECTIVES: Primitive reflexes (PR) generally disappear early in life but may reappear later, in which case they are often associated with chronic neurological conditions, such as dementia or Parkinson's disease. Studies have shown that the presence of PRs may be indicative of both the severity and rate of progression of these diseases and may be the result of disinhibition of cortical networks. The association between PRs and cognitive function in usual ageing is unclear. We investigated whether the occurrence, amplitude, and persistence of four nociceptive (glabbelar tap, palmomental, pollicomental, and snout reflexes), three prehensile reflexes (suck, palmar grasp, and rooting), and two other reflexes (mouth open finger-spread and nuchocephalic reflexes) were related to performance in specific cognitive domains in normal ageing individuals. METHODS: Four-hundred and seventy normal aging participants (25-82 years) in the Maastricht Aging Study (MAAS), were included in the study. They were neurologically and cognitively screened at baseline and were retested after 3 (only individuals aged 50 years and older at baseline) and 6 years. RESULTS: The prevalence of most PRs increased with age: 47% of men aged 25-45 years had at least one PR, compared with 73% of men aged 65-85 year (p = 0.002). In women these percentages were 51 and 75, respectively (p=0.008). The prevalence, amplitude, and persistence of PRs were unrelated to cognition at baseline or at the 3- or 6-year follow-up. CONCLUSIONS: The prevalence of particularly nociceptive reflexes rises substantially with increasing age in normal individuals. However, the presence of PRs cannot be considered to be a marker of cognitive decline in normal aging individuals.

Adult↗

Pulmonary-renal vasculitic disorders: differential diagnosis and management.

Pulmonary-renal syndrome (PRS) is a combination of diffuse pulmonary hemorrhage and glomerulonephritis. Pulmonary-renal syndrome is not a single entity and is caused by a variety of conditions, including Goodpasturés syndrome associated with autoantibodies to the glomerular and alveolar basement membranes, various forms of primary systemic vasculitis associated with serum positivity for antineutrophil cytoplasmic antibodies (ANCA), cryoglobulinemia, systemic lupus erythematosus, systemic sclerosis, antiphospholipid syndrome, environmental factors, and drugs. The majority of cases of PRS are associated with ANCAs. The antigen target in Goodpasturés syndrome is the alpha-3 chain of type IV collagen. The antigen target in PRS associated with systemic vasculitis is proteinase-3 and myeloperoxidase. Pulmonary-renal syndrome has been observed from the first to the ninth decade of life. The widespread adoption of serologic testing performed in an appropriate clinical context hopefully will limit diagnostic delay. The goals of treatment in PRS are to remove the circulating antibodies, to stop further production of autoantibodies, and to remove any antigen that stimulates antibody production. Treatment is based on plasmapheresis, steroids, and cyclophosphamide; however, infections are frequent contributors to death, and less toxic alternatives may improve outcome and prognosis resulting in a long-term survival. The degree of renal function and the percent of crescents on renal biopsy are better predictors of outcome. Renal transplantation can be safely carried out in PRS.

Anti-Glomerular Basement Membrane Disease↗

Positive rolandic sharp waves in neonatal EEG; types and significance.

We describe two types of electropositive rolandic sharp waves (PRS) in EEGs of premature infants with markedly different prognostic implications. Type A occurs singly and is clearly distinguished from the background activity; type B appears in bursts and blends somewhat with the background. Among neonates recorded at less than 35 weeks' conceptional age, 21% of those with type A only had normal neurological examinations or only minor sequelae at age 2 years. When type B appeared in the same tracing as type A, the percentage with normal examinations or minor sequelae at 2 years rose to 86%. Only 42% of those without type A or B had favourable 2 year evaluations. For those recorded at 35 weeks or later, normal or minor sequelae were found at 2 years as follows: type A only - 57%; type B only - 75%; types A and B - 92%; no positive rolandic sharp waves - 53%. We conclude that in both age groups type B PRS confer a relatively favourable prognosis and are more prognostically influential than type A. Patients with either type A or no PRS have less favourable outcomes than those with type B. Finally, although the majority of patients with intraventricular haemorrhage have type A PRS, IVH occurred in only 50% of patients with type A PRS when recorded before 35 weeks' conceptional age.

Cerebral Cortex↗

Tissue-differential expression of two distinct genes for phosphoribosyl pyrophosphate synthetase and existence of the testis-specific transcript.

Cloning of cDNA coding for rat phosphoribosyl pyrophosphate (PPRibP) synthetase (EC 2.7.6.1) revealed two distinct types of subunit, referred to as PRS I and PRS II (Taira et al. (1987) J. Biol. Chem. 262, 14867-14870). Tissue-specific expression of PRS I and PRS II genes (designated PRPS1 and PRPS2, respectively), was shown for 16 rat organs, using Northern blot analysis. The 2.3 kb PRPS1 mRNA level was high in the brain and adrenal gland, whereas the 3.7 kb PRPS2 mRNA level prevailed in the lung and spleen. Both genes were highly expressed in the thymus, adipose tissue and testis. In other mammals (mouse, calf and human), these two types of mRNA were also detected in various tissues and cell lines. Thus, the expression of each gene is regulated in a tissue-specific manner and there may be functional differences between catalytic and/or regulatory properties of subunits PRS I and II of this enzyme. In the testis, an additional PRPS1-related transcript of 1.4 kb was noted in rats, mice and humans. This transcript may belong to a group of testis-specific gene expressions or functions.

Animals↗