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Biomedical subjects

C Young

Publications and source records attributed to C Young.

At least 91 records · Page 5Linked to original sources
PubMed1999

Muscle phosphofructokinase deficiency (Tarui's disease): report of a case.

A 14-year-old girl had an acute episode of rhabdomyolysis after vigorous exercise and seizures. Laboratory studies revealed elevated creatine phosphokinase (CPK) activity and myoglobinuria without acute renal failure, as well as mild indirect hyperbilirubinemia, and hyperuricemia. The elevated CPK activity, mild indirect hyperbilirubinemia, and hyperuricemia persisted during a 10-month follow-up period, during which chronic hemolysis without overt anemia was also noted. A muscle biopsy specimen from the left biceps muscle revealed occasional muscle fiber necrosis and mild excess of glycogen accumulation on periodic acid-Schiff staining. Histochemical reactions were negative with phosphofructokinase (PFK) stain when fructose-6-phosphate was used as the substrate, but positive when fructose 1,6-bisphosphate was used as the substrate. These findings confirmed the diagnosis of muscle PFK deficiency (Tarui's disease), which is a defect of glycolysis in muscles and erythrocytes. Less than 40 such patients have been reported to date. When a specific metabolic myopathy is suspected in children with rhabdomyolysis, symptoms of hemolysis should also be sought to identify Tarui's disease. To the best of our knowledge, this is the first case of Tarui's disease identified in Taiwan.

Adolescent↗
PubMed1998

Partnerships for sound practice.

Our research into clinical supervision is continuing and project members are disseminating clinical supervision throughout the organisation. Evaluation clearly shows that at least 25% of registered nurses are already engaged in clinical supervision. There are no distinct clinical areas that have not supported staff members participating in the project, indicating its widespread acceptance. In addition, we have discovered that staff with the least prior experience of clinical supervision, such as school nurses and health visitors, are committed to its practice. Clinical supervision is no longer seen as the preserve of mental health nurses. The project is enhancing relationships at all levels between nurses. Service development and rigorous research have been closely linked, while, for individual nurses, continuing professional development is offering a pathway to academic qualification.

Community Mental Health Services↗
PubMed1998

An early stage in sodium channel clustering at developing rat neuromuscular junctions.

Voltage-gated sodium channels (VGSCs) are concentrated in the postsynaptic membrane at the adult rat neuromuscular junction (NMJ). We have used immunolabelling to determine the pattern of initial VGSC accumulation during development. At birth, but not 3 days before, VGSC labelling is detectable at the NMJ and in the perijunctional (periJ) membrane but not elsewhere. A much higher density cluster of VGSCs forms at the NMJ itself 1-2 weeks later. If the nerve is cut 2 days after birth, VGSC labelling persists in the periJ region for at least 4 weeks but the clustering of VGSCs at the NMJ fails to develop. Thus an early, stable accumulation of VGSCs develops near the NMJ at least a week before high density postsynaptic VGSC clusters form.

Animals↗
PubMed1998

Cancellation of low-frequency stimulation-induced long-term depression by docosahexaenoic acid in the rat hippocampus.

The effects of docosahexaenoic acid (DHA) on low-frequency stimulation (LFS)-induced long-term depression (LTD) were investigated in the CA 1 subfield of rat hippocampal slices. LTD was routinely produced by LFS of 900 pulses at 1 Hz. The field excitatory postsynaptic potential (fEPSP) 40 min after LFS was 59 +/- 4% (n = 18) of baseline response. However, in experiments from 18 neurons pretreated with DHA (50 microM), fEPSP returned to baseline levels within 20 min after LFS in eight cells and was slightly potentiated in three cells. Only in seven cells was LTD induced. The effect of DHA on LTD was concentration dependent. The slopes of fEPSP 40 min after LFS were 67 +/- 4% (n = 6), 72 +/- 7% (n = 7) and 80 +/- 5% (n = 18) of baseline response, with pretreatment of 1, 10 and 50 microM DHA, respectively. The blockade of LTD induction suggests that DHA may play a role in learning and memory.

Animals↗
PubMed1998

Biallelic expression of all four IGF-II promoters and its association with increased methylation of H19 gene in human brain.

The human IGF-II gene is maternally imprinted in all tissues except adult liver and the choroid plexus/leptomeninges of the central nervous system where IGF-II is biallelically expressed. In human liver, it has recently been reported that this biallelic expression only involves the promoter P1 while the promoters P2-P4 direct IGF-II transcription monoallelically. To explore whether or not biallelic expression of the IGF-II promoters in human CNS displays the same pattern as in liver, we examined the allelic expression status of the four IGF-II promoters in human brain. We found that all four IGF-II promoters in human fetal and adult brain were expressed from both parental alleles. Furthermore, the levels of methylation of the 3' region of H19 gene in fetal brain were higher than those in other tissues with monoallelic expression of IGF-II. Since similar findings have been reported in Wilms' tumor, these data suggest a similar mechanism may be responsible for loss of imprinting of IGF-II in normal brain and Wilms' tumor.

Adult↗
PubMed1998

Utrophin mRNA expression in muscle is not restricted to the neuromuscular junction.

Utrophin is normally present exclusively in synaptic regions of skeletal muscle fibers, although it is expressed extrasynaptically in certain pathological situations, where it has been proposed to compensate for the absence of dystrophin in Duchenne muscular dystrophy patients and mdx mice. Recently there have been conflicting reports regarding the preferential expression of utrophin mRNA at the neuromuscular junction. Using in situ hybridization with RNA probes, we show a clear accumulation of autoradiographic labeling at more than 90% of neuromuscular junctions (identified by histochemical demonstration of cholinesterase activity). The intensity of this labeling is proportional to the number of junctional myonuclei in the section. Some clusters of labeling were found associated with nonmuscle nuclei (e.g., blood vessels, nerves), where utrophin is present. In addition, labeling for utrophin mRNA was associated with about 25% of extrajunctional myonuclei, where the protein is not present. The mean labeling per nucleus at junctional myonuclei was at least 10 times greater than at extrajunctional myonuclei. We discuss the possible regulatory mechanisms involved in the heterogeneous expression of utrophin mRNA in skeletal muscle.

Amino Acid Sequence↗
PubMed1998

Murine neurovirulence studies with a chimeric poliovirus: in vivo generation of a mutant base-paired stable attenuated poliovirus.

We investigated the neurovirulence of a chimeric poliovirus consisting of the coding region of Lansing type 2 poliovirus and the 5'NCR of type 3 poliovirus. Specifically we carried out studies on the effects of stable base pairing, between nucleotides 472 and 537, on neurovirulence. Mice were injected intracranially with the attenuated chimeric virus MAS 27 plaque 1 having the following nucleotide base pair at 472-537, G-G. Mutants recovered from the CNS of inoculated mice were divided into three groups according to the nucleotide sequence of the 5'NCR; MAS 27C type viruses having a single base change (G-C) at the position 472, MAS 27G type mutants having a single base change (G-C) at the position 537, and MAS 27U type viruses having a single base change (G-U) at the position 537. The isolate MAS 27C had back-mutated to the wild type, and 100 000 fold more virulent than attenuated MAS 27G and MAS 27U. MAS 27C type mutants were predominant, suggesting that base C at position 472 is favoured to form a stable secondary structure with guanine at position 537. Attenuated MAS 27G, however, carries guanine and cytosine at nucleotides 472 and 537 respectively, and was a stable attenuated virus following passage in four serial generations of mice. Furthermore, attenuated MAS 27G poliovirus produced viral proteins less efficiently and had slower growth rates than the revertant MAS 27C. The stable attenuated base paired MAS 27G might provide the basis for a prototype for a live attenuated stable type 3 poliovaccine.

Animals↗
PubMed1998

Paxilline-negative mutants of Penicillium paxilli generated by heterologous and homologous plasmid integration.

Using a monoclonal antibody based ELISA, 600 pAN7-1 plasmid-tagged mutants of Penicillium paxilli were screened for paxilline accumulation and one paxilline-negative mutant, YI-20, was identified. A molecular analysis of this mutant showed that pAN7-1 was inserted at a single site but was present as 4-6 copies arranged in a head-to-tail tandem array. Rescue of flanking sequences and analysis of the corresponding genomic region revealed that YI-20 has an extensive deletion at the site of pAN7-1 integration. Probing of a CHEF gel with the same sequences showed that associated with the deletion is a rearrangement of chromosome Va. Targeted gene disruption of wild-type sequences adjacent to the site where pAN7-1 inserted, resulted in the generation of two additional paxilline-negative mutants; both were single crossovers with deletions extending outside the region mapped. Neither of these new mutants had a rearrangement of chromosome Va, suggesting that deletion of genes on this chromosome is responsible for the paxilline-negative phenotype. Telomeric fingerprinting of genomic digests of P. paxilli, combined with pulsed-field gel electrophoresis of chromosomal DNA, established that there are a minimum of eight chromosomes in this fungus.

Chromosome Mapping↗
PubMed1998

Effect of storage temperature on sperm cryopreservation.

OBJECTIVE: To evaluate the influence of cryopreservation temperature on human sperm motility and morphology. DESIGN: Controlled study, investigator was blinded to the type of cryopreservation. SETTING: University-based andrology laboratory. PATIENT(S): Sixteen semen samples with normal motility and sperm count from men after a fertility work up. INTERVENTION(S): Semen aliquots were either stored in a mechanical freezer at -70 degrees C or in liquid nitrogen at -196 degrees C for 7 days or 3 months. Test yolk buffer was used as a cryoprotectant. With use of a programmable freezing unit, all samples were cooled at a controlled rate. MAIN OUTCOME MEASURE(S): Sperm motility and morphology. RESULT(S): After 7 days of cryopreservation, there was a greater decrease in sperm motility among specimens maintained at -70 degrees C than among those maintained at -196 degrees C (47% versus 39% decrease). The difference in sperm motility was even greater after 3 months of cryopreservation (72% versus 39% decrease). No difference in postthaw sperm morphology was detected among sperm preserved at -70 degrees C versus -196 degrees C. CONCLUSION(S): Sperm cryopreservation at -196 degrees C is superior to cryopreservation at -70 degrees C. Sperm can be stored at -70 degrees C for a short period of time with a relatively modest loss of motility.

Cryopreservation↗
PubMed1998

The controversy regarding diagnostic criteria for early myoclonic encephalopathy.

To re-evaluate the diagnostic criteria for early myoclonic encephalopathy (EME), the following study was done. During the past 2 years, five patients with erratic, fragmentary myoclonus of neonatal onset, in association with other types of seizures, were analyzed with regard to etiologies, electroclinical features and their evolution, using a series of examinations including electroencephalographies (EEGs) and metabolic investigations. Of these five patients, three were diagnosed to have non-ketotic hyperglycinemia (NKH); one was pyridoxine-dependent; the other was cryptogenic. Only two cases (one NKH and one cryptogenic) had initial typical suppression-burst (S-B) EEG pattern, which subsequently evolved into multiple paroxysmal abnormalities with random asynchronous attenuation (MP-AA) pattern. The other two cases with NKH had MP-AA EEG pattern throughout both awake and sleep recordings in two consecutive EEG studies. All three cases with NKH survived with increasing microcephaly, muscle tonicity; all developed infantile spasm with hypsarrhythmia on EEGs. The patient with pyridoxine-dependency had an initial MP-AA EEG pattern, which converted into S-B pattern after the first use of pyridoxine, eventually becoming normal after a supplement with the second-dose of pyridoxine. In conclusion, either S-B or MP-AA pattern may reflect the severity of the underlying pathologies or the disease stages. These results suggest that, from both etiological and electroclinical viewpoints, EME may represent a broader spectrum than previously recognized. The still ongoing controversy regarding whether the S-B pattern should be recognized as the sole EEG criteria for the diagnosis of EME needs further experience to clarify.

Age of Onset↗
PubMed1998

Demonstration of a posterior atrial input to the atrioventricular node during sustained anterograde slow pathway conduction.

OBJECTIVES: This study sought to demonstrate electrophysiologic evidence for the existence of different anatomic atrial input sites of fast and slow conduction pathways in patients with dual atrioventricular (AV) node physiology. BACKGROUND: Although a separate posterior exit site exists for a retrograde slow AV node pathway, it remains unresolved whether a separate atrial input site into the AV node actually exists in patients with dual anterograde AV node pathway physiology. METHODS: In 10 patients with dual AV node pathway physiology, atrial pacing at three chosen drive cycle lengths (DCL1, DCL2 and DCL3) was performed at an anterior site (A) just above the His bundle recording site and at a posterior atrial site (P) just below the coronary sinus ostium. DCL3 was chosen as the one cycle length that resulted in a long AH interval consistent with slow pathway conduction. The stimulus to His bundle conduction times (SH) at both sites (SH(P) and SH(A), respectively) and their differences (deltaSH = SH(P) - SH(A)) at each of the three drive cycle lengths were analyzed. RESULTS: The mean +/- SD deltaSH values for DCL1 and DCL2 measured 9 +/- 16 and 8 +/- 18 ms, respectively, and the mean deltaSH value at DCL3 measured -34 +/- 24 ms, which was significantly different from the mean deltaSH values at DCL1 and DCL2 (both p < 0.05). CONCLUSIONS: The significant change in the deltaSH (SH(P) - SH(A)) value during slow pathway conduction could be accounted for by a corresponding shift of anterograde input from an anterior to a posterior entry site to the AV node. These findings support the notion that a separate anterograde entry site of the slow pathway does exist in patients with dual AV node pathway physiology.

Atrioventricular Node↗
PubMed1998

When does Huntington's disease begin?

Recent studies have detected basal ganglia atrophy in clinically asymptomatic persons with the genetic mutation that causes Huntington's disease (HD). Whether reductions in caudate and putamen volume on MRI scans are associated with changes in cognitive and neurologic functioning was examined in 13 healthy adults with the IT-15 mutation. Reduced striatal volume was found to correlate with greater neurologic (largely motor) impairment, slower mental processing speed, and poorer verbal learning, although none of the participants met even liberal criteria for clinical diagnosis of HD. These correlations are strikingly similar to those observed in symptomatic HD patients, possibly reflecting the earliest manifestations of disease.

Adult↗
PubMed1998

An improved method for the simultaneous demonstration of mRNA and esterase activity at the human neuromuscular junction.

The aim of this study was to develop a simple means of studying the distribution of mRNA coding for post-synaptic proteins at the human neuromuscular junction. A reliable method by which to identify the junctions in tissue sections after in situ hybridization was essential. A method is described for combining the histochemical demonstration of esterase activity at the neuromuscular junction with autoradiographic localization of mRNA by in situ hybridization in the same cryostat section of skeletal muscle. The indigogenic esterase method of Strum and Hall-Craggs (1982) was modified in such a way that it is able to survive the multiple steps involved in in situ hybridization and autoradiography. The protocol is simple and reproducible and has been used successfully on sections of both rat and human skeletal muscle. To demonstrate the method, sections were reacted to reveal esterase activity and were then processed for in situ hybridization using a 35S-labelled probe specific for the epsilon-subunit of the acetylcholine receptor. The reaction product was retained after the lengthy in situ hybridization and autoradiographic procedures. To our knowledge, this is the first demonstration of acetylcholine receptor mRNA by in situ hybridization at human neuromuscular junctions.

Animals↗
PubMed1998

Development of a risk assessment for BSE in the aquatic environment.

Bovine spongiform encephalopathy (BSE) is believed to be transmitted by the ingestion of proteinaceous agents called prions which accumulate in the brain and spinal cord of infected bovines. Concern has been expressed about the risks of transmission of BSE to humans through BSE prions discharged to the aquatic environment from rendering plants, abattoirs and landfills. The disease-related form of the prion protein is relatively resistant to degradation, and infectivity decays rather slowly in the environment. Levels of disinfection used for drinking water treatment would have little effect. This paper presents the assumptions which were used to model the risks from a rendering plant disposing of cull cattle carcasses in the catchment of a chalk aquifer which is used for a drinking water abstraction. The risk assessment approach focused on identifying the hydrogeological and physical barriers which would contribute to preventing BSE infectivity gaining entry to the aquifer. These barriers included inactivation of BSE agent by the rendering process, removal from the effluent by treatment at the plant, filtration and adsorption in the clay and chalk, and dilution in the ground water. The importance in environmental risk assessment of the cow-to-man species barrier is considered. Two key conclusions about the environmental behaviour of the BSE agent are that prion proteins are 'sticky' and bind to particulates, and that the millions of BSE prion molecules comprising a human oral ID50 are subject to some degree of dispersion and hence dilution in the environment. Assuming the rendering plant processes 2000 cull cattle carcasses per week, the risks to drinking water consumers were estimated to be remote. Indeed, even using worst case assumptions an individual would have to consume 21 d-1 of tap water for 45 million years to have a 50% chance of infection through drinking water drawn from the aquifer.

Animals↗
PubMed1998

Personal health among midlife women hospital employees.

We hypothesized that women employees working in a hospital environment would be particularly attuned to aspects of personal health, well-being, and disease prevention. We performed an observational study at a local hospital, offering free assessments in its outpatient women's wellness screening program to women employees aged 39-60 years. Data from the first 60 women to enroll in the program are presented as a test of our hypothesis. Undiagnosed hypertension, abnormal lipid profiles, glucose intolerance, alcohol abuse, abnormal cervical cytology, breast masses, depression, or combinations of these were found in 49 of the 60 women. Twenty-one women were obese. Most women with abnormal findings did not follow specific personalized recommendations for remedial follow-up, including referral to a specialist. An important percentage of midlife women employees at this hospital exhibited unhealthful personal behaviors, had unrecognized disease, and did not use recommended health screening practices. The data emphasize the benefit for employees who participate in medical facility worksite health promotion programs.

Adult↗