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Biomedical subjects

A Muller

Publications and source records attributed to A Muller.

At least 91 records · Page 5Linked to original sources
PubMed1996

Genetic evidence for latent Septata intestinalis infection in human immunodeficiency virus-infected patients with intestinal microsporidiosis.

Sequence data of the small subunit rRNA (SSU-rRNA) gene were used to identify Septata intestinalis in biopsies of human immunodeficiency virus-infected patients by polymerase chain reaction (PCR), southern blot hybridization, cloning, and comparative genetic sequencing. DNA products of correct size could be amplified from all examined tissues with S. intestinalis infection but also from 2 biopsies with Enterocytozoon bieneusi and from 1 biopsy with Encephalitozoon cuniculi infection. Southern blot hybridization with an S. intestinalis-specific probe and partial sequencing of the DNA fragments showed high homology with published S. intestinalis sequences and confirmed that the amplified PCR products really derived from the SSU-rRNA gene of S. intestinalis. PCR testing can detect very light infections with S. intestinalis. Thus, S. intestinalis seems to occur more frequently in the form of latent infections and the true prevalence of the parasites may be much higher than previously reported.

Animals↗
PubMed1996

Fiber-specific regulation of Ca(2+)-ATPase isoform expression by thyroid hormone in rat skeletal muscle.

We studied the effect of thyroid hormone (3,5,3'-triiodo-L-thyronine, T3) on the expression of sarcoplasmic reticulum (SR) fast- and slow-type Ca(2+)-ATPase isoforms, SERCA1 and SERCA2a, respectively, and total SR Ca(2+)-ATPase activity in rat skeletal muscle. Cross sections and homogenates of soleus and extensor digitorum longus muscles from hypo-, eu-, and hyperthyroid rats were examined, and expression of Ca(2+)-ATPase isoforms in individual fibers was compared with expression of fast (MHC II) and slow (MHC I) myosin heavy chain isoforms. In both muscles, T3 induced a coordinated and full conversion to a fast-twitch phenotype in one-half of the fibers that were slow twitch in the absence of T3. The conversion was partial in the other one-half of the fibers, giving rise to a mixed phenotype. The stimulation by T3 of total SERCA expression in all fibers was reflected by increased SR Ca(2+)-ATPase activity. The time course of the T3-induced changes of SERCA isoform expression was examined 1-14 days after the start of daily T3 treatment of euthyroid rats. SERCA1 expression was stimulated by T3 at a pretranslational level in all fibers. SERCA2a mRNA expression was transiently stimulated and disappeared in a subset of fibers. In these fibers SR Ca(2+)-ATPase activity was high because of high SERCA1 protein levels. These data suggest that the ultimate downregulation of SERCA2a expression, which is always associated with high SR Ca(2+)-ATPase activities, occurs at a pretranslational level.

Animals↗
PubMed1996

Laser in situ keratomileusis (LASIK) for myopia from -7 to -18 diopters.

BACKGROUND: Laser in situ keratomileusis (LASIK) combines a lamellar corneal flap with an excimer laser ablation in the stromal bed to correct a wide range of myopia. We reviewed 43 eyes treated with LASIK to correct -7.00 to -18.50 diopters (D). METHOD: The data from 43 consecutive eyes of 30 patients aged 24 to 46 years were analyzed. Surgery was performed under topical anesthesia using the Chiron Automated Corneal Shaper and Keracor 116 Excimer laser with the multizone mode and our modified nomogram. Manifest and cycloplegic refraction, uncorrected visual acuity, spectacle corrected visual acuity, videokeratography, endothelial cell count, slit-lamp microscopy, fundus examination, and applanation tonometry were recorded preoperatively and at 1 week and 1, 3, and 6 months, postoperatively. RESULTS: We divided the eyes into two groups. The lower myopia group had a mean preoperative spherical equivalent refraction of -9.30 +/- 1.31 D (range: -7.00 D to -12.00 D) and mean postoperative refraction of -0.80 +/- 0.79 (range: -0.25 D to -3.50 D). The mean spectacle corrected visual acuity preoperatively was 0.74 +/- 0.20 and postoperatively was 0.74 +/- 0.18. The higher myopia group had a mean preoperative spherical equivalent refraction of -14.86 +/- 1.87 D (range: -12.25 D to -18.50 D) and a mean postoperative refraction of -1.80 +/- 1.29 D (range -1.00 D to -5.25 D). The mean spectacle corrected visual acuity preoperatively was 0.50 +/- 0.19 and postoperatively was 0.51 +/- 0.18. No overcorrections occurred in either group. One eye of the higher group lost one line of spectacle corrected visual acuity. No eye had visually significant corneal haze. The mean change in spherical equivalent refraction between preoperatively and 6 months postoperatively was 8.50 D for the lower myopia group and 13.06 D for the higher myopia group, in the myopic direction. Visual rehabilitation was rapid after surgery. CONCLUSIONS: In this study, LASIK resulted in insignificant corneal scarring, stable refractive correction over six months, no irregular astigmatism, and excellent visual acuity. Predictability was more accurate up to -12.00 D of intended correction.

Adult↗
PubMed1996

Evaluation of the Arkansas Medicaid primary care physician management program.

Arkansas implemented a primary-care case-management program in February 1994. This study evaluates the program during its first 17 months. Using quarterly data collected for the Health Care Financing Administration (HCFA), a pooled cross-sectional time series analysis (1991:4-1995:2) estimates the effect of eligibles' program enrollment on expenditure (total, inpatient hospital, outpatient hospital, physicians, prescription drugs, laboratory and X-ray) and utilization measures (outpatient visits, physician visits, prescription drugs). The Arkansas Medicaid managed care program appears to have somewhat reduced growth in total vendor payments and also appears to have improved access to primary medical services.

Aid to Families with Dependent Children↗
PubMed1996

[Acetabular implant in Charnley's total arthroplasty. Review of 309 cases with a minimum of 15 years follow-up].

PURPOSE OF THE STUDY: The aim of this study was to appreciate the long term result of 309 acetabular components of total hip arthroplasty. MATERIALS AND METHODS: All were performed using Charnley's prosthesis and cement, by one surgeon, between January 1972 and December 1975. Clinical function was graded according to Postel-Merle-d' Aubigné's scoring system (PMA score). We measured wear of polythylene using a personal method, on anteroposterior radiographs of the pelvis. Radiolucent line were appreciated by Delee and Charnley's criteria, migration by Massin's criteria. Survivorship curves were calculated with radiolucent lines, as migration, on 15 years. We compared the effect of different parameters on wear and loosening of the sockets. RESULTS: At 15 years follow-up, we found 51.5 per cent hips with the highest PMA score (18). Revision for socket loosening was 3.88 per cent, the same for dislocations. Concerning 25 per cent of the sockets, wear of polyethylene was evaluated less than 0.065 mm a year, concerning 50 per cent of them, it was evaluated less than 0.11 mm a year, at last concerning 75 per cent of them, it was evaluated less than 0.16 mm a year. No significant correlation was established between the tilt of the acetabular component and the wear of polyethylene. We observed no radiolucent lines for 60 per cent of the implants, nor migration for 83 per cent of them. Statistical analysis proved the influence of the wear on radiolucent lines and migration. DISCUSSION AND CONCLUSION: The analysis confirms a moderate wear of polyethylene during 15 years. We introduce an original method for its measurement and its formulation. This method allows a truly description of wear in long term results. This analysis confirms also that several parameters intercede on loosening; these are different if one considers radiolucent lines or migration. We do think at last, that the best positionning of the socket in the A.P. view should approach 35 degrees.

Acetabulum↗
PubMed1996

[What surgical indications remain in the treatment of pain?].

26 out of 39 pain treatment centres answered a questionnaire about surgical management of chronic pain. 12,715 patients have been seen during 1992, suffering mainly from lumbosciatalgia, peripheral nervous system lesions (20% of iatrogenic origins) or cancer pain. 1,635 underwent a surgical procedure on: lumbar chain (520), Vth cranial nerve (448), spinal cord (225 electrical stimulations), splanchnic nerves (171). Ablative surgery on somatic nerves retains only minor indications, in contrast to an increase in the frequency of stimulation techniques.

Cranial Nerves↗
PubMed1996

Alcohol consumption and community hospital admissions in the United States: a dynamic regression analysis, 1950-1992.

The annual time-series analysis examines the impact of changes in per capita alcohol consumption (NIAAA,AEDS) on changes in community hospital admission rates (AHA) in the United States from 1950 to 1992 (n = 43). Increases in per capita alcohol consumption were expected to increase hospital admission rates contemporaneously and several years thereafter following an exponential risk function. Distributed lag models based on differenced data controlling for changes in: (1) per capita cigarette consumption; (2) private hospital insurance coverage; (3) the drinking age population; (4) per capita disposable personal income; and (5) health care regulatory interventions show a contemporaneous effect of per capita alcohol consumption on hospital admission rates. The time-series analyses imply that between 22-26% of US community hospital admissions are alcohol related. A comparable analysis indicates that per capita alcohol and tobacco expenditures contribute to approximately 28% of US community hospital admissions. The absence of statistically significant lagged effects is inconsistent with an exponentially declining risk functions. However, the contemporaneous effects of per capita alcohol and tobacco consumption suggest that a reduction in smoking and drinking will produce quick reductions in morbidity and hospitalizations.

Alcohol Drinking↗
PubMed1995

Calcium-dependent free radical generation in cultured retinal neurons injured by kainate.

Cultured rat retinal neurons exposed to kainate produced free radicals, as demonstrated by electron spin resonance (ESR) spin trapping using the nitrone 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) and the generation of DMPO hydroxyl adduct (DMPO-OH). This DMPO-OH production was abolished by EGTA, nitro-arginine and oxypurinol, suggesting that it was dependent on Ca2+ influx and subsequent activation of nitric oxide synthase and xanthine oxidase. Moreover, kainate induced a receptor-mediated Ca2+ influx and neuronal injury assessed by lactate dehydrogenase release. Neuroprotection afforded by nitro-arginine and oxypurinol shows that calcium-dependent free radical production plays a major role in kainate retinal toxicity.

Animals↗
PubMed1995

The influence of experimental ischaemia on protein kinase C and the GABAergic system in the rabbit retina.

Pressure-induced ocular ischaemia followed by 25-28 hr of reperfusion to the rabbit retina drastically reduces or eliminates the b-wave of the electroretinogram and results in all the GABA from the amacrine cells being released, as judged by immunohistochemistry. Some of these GABA cells have the capacity to take-up exogenous serotonin and these GABA/serotonin cells have kainate/AMPA receptors. Previous studies have shown that an ischaemic insult causes these receptors to be stimulated to produce a release of the cells' GABA. The majority of the GABA/serotonin cells are also incapable of taking-up exogenous serotonin after ischaemia, which suggests that they are irreversibly damaged. However, there was still a minority of the cells which accumulated serotonin, which shows that neurones containing kainate/AMPA receptors are not irreversibly damaged at the same rate by ischaemia. The "staining" patterns for GABAA-receptor and GABA immunoreactivities in the rabbit retina are very similar and following ischaemia the GABAA-receptor immunoreactivity was reduced in intensity and became patchy in nature. It is not known whether this result reflects a down-regulation of the GABAA-receptors caused by the released GABA or a destruction of cells containing the GABAA-receptors. The ischaemic conditions used caused patchy, irregular and inconsistent signs of histological damage to the retina, even in areas of similar eccentricity, suggesting this parameter should be used with caution when judging the severity of an ischaemic insult. alpha-Protein kinase C (alpha PKC) present in the on-bipolar cells which have glutamate metabotropic APB receptors is both reduced or down-regulated and translocated by ischaemia. This is also the case for delta PKC which is absent from the on-bipolar cells. These data were established by a combination of immunohistochemistry and electrophoresis/blotting experiments. Enzyme analysis also showed that all PKC calcium-dependent and -independent isoenzymes, are translocated and reduced by ischaemia making it difficult to judge whether PKC inhibitors may be appropriate anti-ischaemic agents.

Animals↗
PubMed1995

Exposure of energy-depleted rat trabeculae to low pH improves contractile recovery: role of calcium.

The beneficial effect of low pH during cardiac ischemia on reperfusion injury has often been attributed to its energy-saving effect due to inhibition of contraction. The role of low pH on Ca2+ accumulation and muscle tension was assessed in energy-depleted tissue by changing the pH of the medium from 7.4 to 6.2 at onset of rigor development during metabolic inhibition (MI), i.e., in the energy-depleted phase. Cytosolic free Ca2+ ([Ca2+]i) and intracellular H+ (pHi) were measured in rat trabeculae at 20 degrees C with fura 2 and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, respectively, and tension was recorded. The preparations were energy depleted by stimulation at 1 Hz in glucose-free Tyrode solution with 2 mM NaCN. Rigor developed within 20 min, indicating energy depletion. Resting [Ca2+]i was followed during 50 min (group I) or 100 min (group II) of rigor, and recovery was followed for 60 min in glucose-containing Tyrode solution at 0.2-Hz stimulation. Resting [Ca2+]i rose within 50 min (group I) but stabilized in the 50- to 100-min period (group II). All preparations from group I (n = 5) resumed contraction in the recovery period but in group II (n = 10) 70% failed to recover, and [Ca2+]i remained elevated compared with those that recovered. An extracellular pH of 6.2, resulting in similar pHi, from onset of rigor development (group III) led to only a modest rise in [Ca2+]i during the 100-min rigor period, and all preparations resumed contraction after approximately 3 min in normal medium. ATP was very low in all groups at the end of MI but was still significantly lower in group II than in groups I and III. A beneficial energy-sparing effect of low pH during the rigor phase can therefore not be excluded. We conclude that 1) the capacity of trabeculae to recover from MI depends on the time period and magnitude of the [Ca2+]i rise in the energy-depleted phase and 2) low pH in energy-depleted trabeculae protects against Ca overload, improving recovery after normalization of perfusion conditions.

Animals↗
PubMed1994

Differential regulation of the expression of fast-type sarcoplasmic-reticulum Ca(2+)-ATPase by thyroid hormone and insulin-like growth factor-I in the L6 muscle cell line.

The aim of this study was to investigate the mechanism(s) underlying the thyroid-hormone (L-tri-iodothyronine, T3)-induced elevation of fast-type sarcoplasmic-reticulum Ca(2+)-ATPase (SERCA1) levels in L6 myotubes and the potentiating effect of insulin-like growth factor-I (IGF-I) [Muller, van Hardeveld, Simonides and van Rijn (1991) Biochem. J. 275, 35-40]. T3 increased the SERCA1 protein level (per microgram of DNA) by 160%. The concomitant increase in the SERCA1 mRNA level was somewhat higher (240%). IGF-I also increased SERCA1 protein (110%) and mRNA levels (50%), whereas IGF-I + T3 increased SERCA1 protein and mRNA levels by 410% and 380% respectively. These SERCA1 mRNA analyses show that the more-than-additive action of T3 and IGF-I on SERCA1 expression is, at least in part, pre-translational in nature. Further studies showed that the half-life of SERCA1 protein in L6 cells (17.5 h) was not altered by T3. In contrast, IGF-I prolonged the half-life of SERCA1 protein 1.5-1.9-fold, which may contribute to the disproportional increase in SERCA1 protein content compared with mRNA by IGF-I. Measurements of SERCA1 mRNA half-life (as determined by actinomycin D chase) showed no difference from the control values (15.5 h) in the presence of T3 or IGF-I alone. When T3 and IGF-I were both present, the SERCA1 mRNA half-life was prolonged 2-fold. No significant effects of T3 and IGF-I were observed on the half-life of total protein (37.4 h) and total RNA (37.0 h). The absence of an effect of T3 on SERCA1 protein and mRNA stability, when it was present alone, suggested transcriptional regulation, which was confirmed by nuclear run-on experiments, showing a 3-fold increase in transcription frequency of the SERCA1 gene by T3. We conclude that the synergistic stimulating effects of T3 and IGF-I on SERCA1 expression are the result of both transcriptional and post-transcriptional regulation. T3 acts primarily at the transcriptional level by increasing the transcription frequency of the SERCA1 gene, whereas IGF-I seems to act predominantly at post-transcriptional levels by enhancing SERCA1 protein and mRNA stability, the latter, however, only in the presence of T3.

Animals↗
PubMed1994

Differential effects of thyroid hormone on the expression of sarcoplasmic reticulum Ca(2+)-ATPase isoforms in rat skeletal muscle fibers.

Thyroid hormone increased the percentage of fibers expressing fast-type sarcoplasmic reticulum Ca(2+)-ATPase in the slow rat soleus muscle from 17% in the hypothyroid to 100% in the hyperthyroid state. This was accompanied by a 12-fold increase in the fast-type Ca(2+)-ATPase protein content of soleus muscle homogenates, suggesting that also the amount of this protein per muscle fiber was increased. In contrast to the fast-type isoform, a decrease in the percentage of fibers expressing slow-type Ca(2+)-ATPase from 100% to 70% was observed in the transition from the hypothyroid to the hyperthyroid state. Slow-type Ca(2+)-ATPase protein levels in muscle homogenates however did not decrease on the same trajectory, but were even elevated in the euthyroid state. In the fast extensor digitorum longus muscle qualitatively similar changes in Ca(2+)-ATPase isoform expression were observed. The results suggest a dual action of thyroid hormone: 1. increasing slow-type Ca(2+)-ATPase expression in individual fibers 2. decreasing the fraction of slow-type Ca(2+)-ATPase expressing fibers.

Animals↗